Phylogeny and Evolution of Myrmecophily in Beetles, Based on Morphological Evidence (Coleoptera: Ptinidae, Scarabaeidae)

Home , Adranes, Anobiinae, Ant, Bostrichoidea, Claviger (beetle), Cremastocheilini

Phylogeny and Evolution Of Myrmecophily In Beetles, Based On Morphological Evidence (Coleoptera: Ptinidae, Scarabaeidae)

DISSERTATION

Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the Graduate School of The Ohio State University

Glené Mynhardt

Graduate Program in Evolution, Ecology and Organismal Biology

The Ohio State University

2012

Dissertation Committee:

Johannes Klompen, Advisor

Marymegan Daly

Norman Johnson

T. Keith Philips

Glené Mynhardt

2012

Abstract

Ant-associated behavior has evolved rampantly among various groups of

Arthropoda, and has arisen in at least 34 families of beetles. Due to the amazing morphological modifications and different kinds of interactions that occur within myrmecophilous (ant-associated) beetles, authors have predicted that myrmecophily has evolved in a step-wise fashion from casual, facultative associations to closely integrated, obligate interactions. In this dissertation, myrmecophily within the Coleoptera is reviewed, and known behaviors, ant-beetle interactions, and associated morphological adaptations are discussed. In order to better understand how myrmecophily has evolved, two groups of beetles are studied in a phylogenetic context. A cladistic analysis of 40 species of the myrmecophilous scarab genus, Cremastocheilu s Knoch is presented.

Characters related to a myrmecophilous habit are largely informative, especially those characters related to the glandular trichomes (clusters of setae typically associated with exocrine glands). Two of the five previously recognized subgenera, C. (Myrmecotonus ) and C. (Anatrinodia ) are synonymized with the subgenus C. (Cremastocheilus ). Even

though behavioral information is only known for a few species, the resulting phylogeny

indicates that monophyletic subgenera are largely associated with the same ant hosts,

although specific interactions with ant hosts can vary even in closely-related taxa. In

addition, a separate cladistics analysis of the spider beetles based on morphology is

ii presented. The monophyly of previously proposed suprageneric groups are investigated, and eight tribes of spider beetles (four unnamed basal tribes, plus more derived Gibbiini,

Ptinini, Sphaericini) are recognized to capture three unique monophyletic groups of spider beetles. Of eight myrmecophilous spider beetle genera, only one genus ( Gnostus ) can be placed, all other myrmecophilous representatives remain unplaced in phylogeny.

Based on this analysis, myrmecophily has evolved independently in four lineages, with nearly all genera appearing basal in spider beetle phylogeny. Based on these findings, obligate myrmecophily has evolved in four different groups. Among the Old World taxa

(South African, Australian), and based on morphology, antennae may have evolved in a step-wise fashion, from less specialized (normal, 11-segmented antennae) to more highly specialized (reduced, with fusion of segments); however, pronotal trichomes are present in all related taxa. Among New World taxa, the presence of unique myrmecophilous adaptations indicates rapid evolution of obligate ant-associated behavior and morphology, rather than step-wise evolution from casual or facultative to obligate associations.

Finally, two new genera of Dominican amber spider beetles are described. The new genus Electrognostus may indicate a transition from a normal Ptinus -like spider beetle to a myrmecophilous type like Gnostus , but based on the phylogenetic analysis it can currently be placed within the Ptinini tribe.

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This document is dedicated to the many people who gave me strength to believe in

myself.

Acknowledgments

I have a lot of people to thank for guiding and supporting me through this interesting venture called graduate school. I have to thank my family first, for giving me the opportunity to study biology, fall in love with insects, and pursue the study of some of the coolest beetles on Earth. Thanks, Anna Mynhardt, my mom, for being there on days that were less than great, and for supporting me and pushing me on days when doing all this felt right. To my dad, Hendrik Mynhardt, for instilling the drive and passion in me to always strive for more. And to my brother, Gavin Mynhardt, for being strong for me and for you. Within the first year of graduate school I met Jason Kolenda, a man who has stood by me through all the ups and downs and has carried me through some of the hardest days of my life. Thank you for making me laugh. Thank you to Jane, Dave, and

Aaron Kolenda for making me see what life is really about – having the right people by your side. Thanks to “Grandpa” Herman Lubertazza, Laurie Parham, the Meserini family,

Carney, Cheryl, Pat, Nathan, and Danny Lubertazza.

Thanks to all my friends, Ashley Kulhanek, Meaghan Ventura, Joshua Bryant,

Kaitlin Uppstrom, Monica Farfan, Erin Morris, Chelsea Korfel, the Cary family, The

Meehl family, the Rinas family, the Spilker family, and Heather Stephens – you were all there for me at different times during this journey. Thank you Kathy Horava, Judith

Cusin, Joelle Fenger, Reni Ayachitula, Lynn Healy and Joanne Strunk for your constant

v encouragement and for making me feel like I could conquer the world. I would have been much less of a person without you. Thanks to my many friends at the Museum of

Biological Diversity – Abby Reft, Ryan Caesar, Joe Raczkowski, Charuwat Taekul,

Brandon Sinn, Ryan Folk, Paul Larson, Jason Macrander, Sam Bolton, Luciana Musetti,

Mesfin Tadesse, John Freudenstein, and Steve Passoa for helping me with so many little things that I couldn’t have done without.

I also have to thank some of the most important mentors and advisors who have led me to become a better scientist, a better thinker, a better writer, and a more confident person. Even though you left for something much bigger and better, John Wenzel, thanks for making me believe in me, and for letting me grow as a teacher. Thanks for letting me find myself, even if it meant struggling to get there. Thanks to one of the most efficient and kind people I know - Hans Klompen, who kindly adopted me and gave me the discipline and the guidance to finish. Thank you also to my other committee members,

Meg Daly and Norm Johnson, for making me stronger, even if it meant questioning myself on a daily basis. I couldn’t have done any of this without my good friend, mentor, and colleague, Keith Philips. You are a true example of what it means to be a good scientist. Thank you for sharing your passion for spider beetles with me. You gave me the ideas and motivation to keep going. And to Linda Gerofsky for being like an academic mother when I needed it most.

Thank you to Judy Ridgway, from the bottom of my heart, for making me become the teacher that I am, and for giving me the support I needed to pursue my teaching goals.

You have been a mentor, a confidant, a friend, and an inspiration in so many ways.

Thanks also to the newest friends I have made at the University Center for the

Advancement of Teaching: Alan Kalish, Kathryn Plank, Teresa Johnson, Stephanie

Rohdieck, Laurie Maynell, Jerry Nelms, Jennie Williams, Christy Anandappa, and to my fellow graduate consultants, Sharon Ross, Lindsay Bernhagen, Spencer Robinson, and

Monica Kowalski. We all took different paths to end up together in a great place.

Thank you also to all the many people who loaned me specimens, especially James

Harrison, and to all of those who successfully talked me into studying myrmecophiles –

Gary Alpert and Bill Warner. And to another person who knows how to share his love for knowledge, Xavier Bellés, thanks for promoting spider beetle research.

Finally, thank you to all my students who made me become the teacher and the scientist that I’ve become. You are the reason I finally got to this stage. I was a student once, who didn’t quite know where I would end up. Follow your dreams. I did, and even though I’m still searching for answers and for my place in life, I never stop trying.

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Vita

May 2000 ...... James Bowie High School

2004...... B.S. Biology, University of Texas at Austin

2006...... M.S. Entomology, Texas A&M University

2006 - 2010 ...... Graduate Teaching Associate, Center for

Life Sciences Education, The Ohio State

University

2010 - present ...... University Center for the Advancement of

Teaching, The Ohio State University

Publications

Mynhardt G. 2011. Growing into teaching: A graduate student’s journey. Talking about Teaching 5:26-29.

Philips T. K. & Mynhardt G. 2011. Description of Electrognostus intermedius , the first spider beetle from Dominican amber with implications for spider beetle phylogeny (Coleoptera Ptinidae). Entomapeiron 4:37-51.

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Mynhardt G. & Wenzel J. W. 2010. Phylogenetic analysis of the myrmecophilous Cremastocheilus Knoch (Coleoptera: Scarabaeidae: Cetoniinae) based on external adult morphology. Zookeys 34:129-140.

Abbott J. C. & Mynhardt, G. (2007). Description of the larva of Somatochlora margarita (Odonata: Corduliidae). International Journal of Odonatology 10:129-136.

Mynhardt G., Cognato A.I & Harris M. K.. 2007. Population genetics of the pecan weevil, Curculio caryae Horn (Coleoptera: Curculionidae), based on mitochondrial DNA data. Annals of the Entomological Society of America 100:582-590.

Fields of Study

Major Field: Evolution, Ecology and Organizmal Biology

Table of Contents

Abstract ...... ii

Acknowledgments...... v

Vita ...... viii

Publications ...... viii

Fields of Study ...... ix

Table of Contents ...... x

List of Tables ...... xiv

List of Figures ...... xv

Chapter 1: Introduction ...... 1

Chapter 2: A review of myrmecophily in Coleoptera ...... 3

2.1 Introduction to myrmecophily ...... 3

2.2 Definitions and classifications of myrmecophily ...... 9

2.2.1 Attempts to classify myrmecophily ...... 9

2.2.2. An overview of myrmecophilous categories ...... 10

2.2.3. Problems with the proposed classifications of myrmecophily ...... 16

2.2.4. Using ecological data to classify myrmecophilous Coleoptera ...... 21

2.2.5. Using morphology to classify myrmecophilous Coleoptera ...... 29

2.3. Evolution of myrmecophily ...... 36

2.3.1. Overview ...... 36

2.3.2. Stages of myrmecophily ...... 37

2.3.3. Larvae as indicators for evolution of myrmecophily ...... 40

2.3.4. Defensive to integrated forms ...... 42

2.3.5. Summary and future work ...... 45

Chapter 3: Phylogenetic analysis of the myrmecophilous scarab genus, ...... 48

Cremastocheilus knoch ...... 48

3.1. Abstract ...... 48

3.2. Introduction ...... 49

3.3 Methods ...... 54

3.3.1. Analysis ...... 54

3.3.2. Characters used in analysis ...... 56

3.4. Results ...... 72

3.5. Discussion ...... 73

3.5.1. Subgeneric monophyly ...... 73

3.5.2. Characters of phylogenetic importance ...... 78

3.5.3. The evolution of myrmecophily in Cremastocheilus ...... 82

Chapter 4: Phylogenetic analysis and evolution of myrmecophily in the spider beetles.. 85

4.1. Introduction ...... 85

4.1.1. Spider beetle taxonomy ...... 85

4.1.2. Subfamilial taxonomy of the spider beetles ...... 88

4.1.4. Myrmecophilous spider beetles ...... 90

4.2. Materials and Methods ...... 94

4.2.1. Taxon sampling ...... 94

4.2.2. Coding and analysis ...... 96

4.2.3. Characters coded ...... 99

4.3. Results and Discussion ...... 135

4.3.1. Analysis ...... 135

4.3.2. The spider beetles ...... 136

4.3.3. Tribal and suprageneric groups ...... 139

4.3.4. Myrmecophilous spider beetles ...... 146

Chapter 5: Description of two new genera of Ptinidae from Dominican amber ...... 152

5.1. Abstract ...... 152

5.2. Introduction ...... 152

5.3. Materials, methods, and descriptions ...... 154

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5.4. Comparison and phylogenetic implications ...... 168

5.4.1. Genus Electrognostus ...... 168

5.4.2. Genus Okamnina ...... 170

5.4.3. Summary ...... 172

References ...... 174

Appendix A: Morphological matrix for Cremastocheilus analysis ...... 184

Appendix B: List of known spider beetle taxa...... 186

Appendix C: Morphological matrix for spider beetle analysis ...... 192

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List of Tables

Table 1. Behavioral classification and placement by major author ...... 47

Table 2. Taxonomic history of the subgenera within Cremastocheilus (*denotes inclusion

of C. wheeleri ) ...... 84

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List of Figures

Figure 1. Differences in pronotal angles in Genuchinus (A), and Cremastocheilus (B);

arrow indicates pronotal angle ...... 50

Figure 2. Mentum of Cremastocheillus species ...... 58

Figure 3. Oblique view of pronotum of Cremastocheilus ; C. (Trinodia ) hirsutus , A; C.

(Cremastocheilus ) mexicanus , B; C. (Cremastocheilus ) schaumi , C...... 67

Figure 4. Pronotal diversity in Cremastocheilus species; C. (Myrmecotonus) angularis, A;

C. (Cremastocheilus) castanae, B; C. (Macropodina) depressus, C; C. (Cremastocheilus)

harrisii, D; C. (Trinodia) hirsutus, E; C. (Anatrinodia) wheeleri ...... 68

Figure 5. Modified fore tarsus of C. (Macropodina ) beameri ...... 71

Figure 6. Strict consensus of 24 equally parsimonious trees of Cremastocheilus (153 steps; CI = 0.46, RI = 0.80) . Bold numbers above lines indicate Jackknife values; numbers below lines indicate Bremer support values...... 76

Figure 7. Maxillae of Ptilinus (A), Hanumanus (B), and Scaleptinus (C) ...... 106

Figure 8. Metasternites of spider beetles; Eutaphrimorphus (A), Neoptinus (B), and

Casapus (Casapus ) ...... 120

Figure 9. Acanthaptinus triplehorni , showing crenulate patterns (punctures) along abdominal ventrite sutures ...... 134

Figure 10. Eutaphrimorpus raffrayi , broken sutures along first and second ventrites

(arrow)...... 134

Figure 11. Strict consensus of the spider beetles, based on 47 equally parsimonious trees

(860 steps, CI=0.19, RI=0.52) ...... 138

Figure 12. Electrognostus intermedius n. gen., n. sp., dorsal (1-2) and ventral (3-4) view

(from Philips & Mynhardt 2012) ...... 157

Figure 13. E. intermedius, lateral view (5-7); antenna (8) ...... 159

Figure 14. E. intermedius, paratype ...... 160

Figure 15. Okamnina carinae , lateral (A) and dorsal (B) views ...... 164

Figure 16. Okamnina annae , lateral (A) and dorsal (B) views ...... 167

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Chapter 1: Introduction

Myrmecophily is a complex behavioral phenomenon known to occur in many groups of organisms, particularly in arthropods. Organisms that are “myrmecophilous” are associated with ants, with specific interactions ranging from accidental to parasitic and even symbiotic associations. Following hypotheses made by the German myrmecologist, Erich Wasmann, various authors have proposed different nomenclatural or classification systems that define the different associations. In various seminal works by Wasmann (1894, 1898), he suggested that myrmecophily evolves from less complex

(facultative) to more complex (obligate) types of interactions. Provided that phylogenetic information is lacking for many myrmecophilous groups, and the fact that behavioral information is largely unavailable, very little work has been done to study how myrmecophily evolves. Due to the lack of behavioral data for the majority of myrmecophilous beetles, morphology is often the only source of data available for studying patterns of evolution within these organisms. Several objectives are pursued throughout the four major chapters within this dissertation.

In Chapter 2 myrmecophily within the Coleoptera (beetles) is reviewed.

Nomenclatural systems that define the various interactions are examined, and a new classification-free system for describing the various interactions between ants and beetle

1 myrmecophiles is presented. In addition, a general overview of how authors have viewed the evolution of myrmecophily is outlined. In Chapter 3 the first cladistic analysis of a unique scarab genus, Cremastocheilus Knoch, based on morphological data, is presented, and the evolution of myrmecophily and ant-associated characters and a few known behaviors within the group are discussed.

In Chapter 4 a different group of insects, known as the spider beetles (Ptininae), are examined, and a phylogenetic analysis of the group, based on morphological characters, is presented. As part of this chapter, the morphological analysis by Philips

(2000) is updated by testing monophyly of various suprageneric and tribal groups previously proposed by Xavier Bellés (1985). The evolution of myrmecophily within the spider beetles is also discussed, and the phylogenetic placement of eight myrmecophilous genera is attempted. Finally, in Chapter 5 two new genera of extinct spider beetles from

Dominican amber deposits are described. These new spider beetles are discussed in terms of the potential phylogenetic affinities to extant spider beetles, and also in terms of how myrmecophily has evolved within the Ptininae.

Chapter 2: A review of myrmecophily in Coleoptera

2.1 Introduction to myrmecophily Ants are one of the most biologically complex groups of animals in existence today. Combined with other social insects including termites, bees, and wasps, ants occupy over 75% of the total insect biomass in forests and savannas (Beck 1971), and a single colony can consist of anywhere between a few to more than 300 million individuals (Hölldobler & Wilson 1990). Unlike other social insects, ants are able to occupy a wider range of habitats and therefore a much more diverse niche space. They also vary from being one of the predominant terrestrial predators of other insects (Wilson,

1971) to one of the leading herbivorous (plant feeding) or granivorous (seed feeding) groups in any single area. The ability for ants to reach extremely high densities while exploiting a variety of food resources leads to high concentrations of brood and larvae, stores of seeds and other gathered materials, and even decomposing ants that have died within the colony. These abundant quantities of materials within an ant nest are particularly so among the two most speciose ant subfamilies, the Myrmecinae and

Formicinae. These two subfamilies are typified by larger nests, more brood, greater food stores, and the general complexity of their nests (Wheeler 1910). Their and other ant nests are often compared to ecological islands (Wilson 1971) that provide other

3 organisms with unexplored niche space, abundant resources, and the potential for colonization.

Given that ants must manage resources, find new areas to establish colonies, and maintain brood and larvae, they have developed variable but complex systems of communication that depend primarily on chemical signals and cues that govern the activities that occur within an ant colony. Members within a colony communicate about food gathering or caring for brood, and a standard, usually species- or colony-specific chemical signature alerts members that they are of same colony. This keen sense of kin recognition makes ant nests extremely inhospitable to intruders, but many other organisms have managed to overcome ant defenses. The known associations of other organisms with ants vary greatly, but visitors to an ant nest possess many differing mechanisms of avoiding, overcoming, or thriving on factors that would otherwise prevent them from entering ant nests or interacting with the ants themselves. Organisms that are associated with ants are typically called ant “inquilines,” which is usually broadly defined as organisms that live with ants for at least one life stage. More commonly, organisms that are associated in any way with ants are called “symbionts,” due to the inherent symbiotic relationships fostered between ants and their associates. The term “symbiont” is not necessarily useful for interactions that aren’t mutually beneficial, although it is broadly used. Similarly, the term “inquiline” does not apply to a wealth of organisms that do not rely on ant nests as a source of habitat. For purposes of this review, they will together be combined into a larger category called known as “myrmecophiles,” or

“associates” in more general terms, largely to include the broad range of interactions that are present among those organisms that are associated with ants.

Arthropods are among the most specialized and well-studied myrmecophilous groups of organisms. The existing literature on myrmecophiles is extensive, although treatment of the majority myrmecophiles is superficial and cursory at best. According to

Hölldobler & Wilson’s (1990) most recent catalogue of myrmecophiles in The Ants , there are at least 95 families of non-insect arthropods associated with ants, including 5 genera of isopods, two genera of pseudoscorpions, 18 of aranaeid spiders, 19 of mites, 8 of millipedes, and 96 families of insects. Limited behavioral information exists for the majority of these groups, and for many only presumed or “possible” behavioral interactions have been recorded based on the behavior known for close relative, or sometimes because of unique morphology that might be indicative of specific interactions. Even the most diverse ant-associated organisms, such as mites, which have been recorded in numbers as high as 42,000 in a single ant nest (Rettenmeyer 1963), are not well studied, although a few genera and species are very well known in their ectoparasitic interactions with ant hosts. Despite the lack of knowledge of many interactions among myrmecophiles and their hosts, a few insect groups have been studied sufficiently to understand interactions between ants and their guests and include, for example, ant-aphid mutualism, ant-lycaenid interactions, and certain ant-beetle symbioses.

The most well-known model system used to describe myrmecophily includes aphids and ants. Aphids secrete honeydew, which is a sugar-rich, amino-acid poor

5 substance released as a byproduct of feeding on plants. Ants “milk” aphids for honeydew and in turn protect aphids against natural enemies. Interactions are largely uniform in all aphid-ant systems, although the degrees to which aphids are associated with ants vary, so that some interactions are obligate, and others are facultative (Shingleton & Stern 2003).

Similarly, ant-associated lycaenids are largely associated with ants that tend Homoptera.

Of the nearly 1000 lycaenid species, at least 75% interact with ants (Pierce et al. 2002), although these interactions vary and can range from obligate to facultative as well as mutualistic to parasitic types, and are primarily restricted to larvae. Respective interactions rely mostly on chemical mediation in which larvae will utilize a variety of glands or “ant organs” that allow them to manipulate ants into accepting them into the ant colony, after which the majority feed on ant brood instead of the typical herbivorous food sources known for most Lepidoptera. Interactions among lycaenids and their ant hosts are variable, but morphological adaptations to associations with ants are relatively uniform, i.e. all bear a combination of organs positioned in the same physical areas that either pacify ants or act as a means of defense against ants (Fiedler 1991, Stadler et al. 2003).

Coleopterous (beetle) myrmecophiles are commonly found in the literature, but are not necessarily extensively studied. Among the better-known groups, especially in terms of behavior, is the Staphylinidae, specifically the subfamilies Aleocharinae and

Pselaphinae. Not all Aleocharinae are myrmecophilous, but for those that are, behavior and morphology in relation to myrmecophily is highly variable, ranging from casual interactions, often associated with mimicry of ants in foraging trails, to closely associated inquilines that exchange fluids with ants via oral trophallaxis. Within the Pselphinae, only

6 a few are myrmecophilous, and two genera, Adranes (from North America) and Claviger

(from Europe) are some of the best known in terms of behavior and unique morphology.

Representatives of both genera typically interact with ant larvae, with which they share oral fluids. Both genera are also predaceous on ant larvae. Myrmecophilous Aleocharinae are relatively well known behaviorally, especially in relation to the army ant , Eciton burchelii ; however, given that the Aleocharinae as a whole have posed significant challenges taxonomically, myrmecophilous groups are not yet well understood, except for a few scant works by, for example, Danoff-Burg 1994, on a three-species tribe

Sceptobiini. Among myrmecophiles, behavioral characters have been analyzed (Danoff-

Burg 1994, 2002) and morphology of adults and larvae have been utilized to resolve some of the deeper phylogenetic relationships in the subfamily (Ashe, 2005).

The only other beetle group that is understood as well as the staphylinids is the scarab genus Cremastocheilus . While behavioral data exist for only a few species, morphology is largely uniform for species of the genus. All of them bear trichomes, or tufts of stout setae, on the pronotum, along with associated glands. The role that these glands and trichomes play is largely unknown except in a few species, such as

Cremastocheilus stathamae (Cazier & Mortenson 1965) or C. armatus (Alpert & Ritcher

1975). It is largely assumed that the glands appease ants into accepting beetles as members of the colony, and has been supported with experimental evidence by Alpert

(1994); however, some species have been shown to be entirely rejected by ant hosts.

Within the genus, even closely related species behave very differently in response to ants

(Alpert 1994), suggesting that behavior and morphology are not necessarily correlated.

Even though Cremastocheilus is one of the most well recognized myrmecophilous beetle groups, very little is known about the biological interactions between the beetles and their ant hosts, except for the few species mentioned.

For most other beetles much of the existing behavioral information is based on isolated observations?, or even only presumed associations with ants, particularly if the group of interest bears unique morphological characteristics thought to be due to myrmecophilous interactions. Wilson (1971) provided the first extensive list of known beetle myrmecophiles from all over the world, which includes 35 beetle families documented to have associations with ants. This may not be surprising since beetles are the most diverse group of insects, and, among the beetles the various kinds of behavioral and morphological adaptations to respective ant hosts are greater than those utilized in any other insect order. The majority of insect myrmecophiles act as predators in some stage of life, and feed on ant larvae or adults and some solicit food from ant hosts. Others are scavengers, feeding on debris or in refuse deposits within the ant nests, and usually have little interaction with the ants themselves. Of all the interactions documented between myrmecophiles and ants, the Coleoptera employ all of them.

The varying kinds of interactions of beetles and other insects with ants have led to numerous definitions and categories aimed at describing particular myrmecophilous behaviors. These various schemes are often used as a means to determine whether the organism of interest is in the process of an evolutionary shift from a “casual” associate to a more integrated one. Many authors, described below, have attempted to place the many

8 species of known myrmecophilous beetles into their prescribed categories, although the utility or application of these systems is questionable, particularly if taxa are only placed in specific categories for the sake of simplifying the usually highly complex interactions that are actually occurring.

2.2 Definitions and classifications of myrmecophily

2.2.1 Attempts to classify myrmecophily

In more than 140 papers the German myrmecologist, Erich Wasmann, laid the groundwork for studies on myrmecophily, contributing a great body of work to ant- associated behaviors. Specifically, the majority of his papers were focused on myrmecophilous Coleoptera, although he also described various behaviors related to termitophily, or termite-associated behaviors. Before Wasmann, isolated records of various myrmecophilous Coleoptera had been documented in major contributions by several authors (Muller 1818; Maerkel 1841, 1844; von Hagens 1863, 1865; White 1872;

Lespes 1885; Hamilton 1888, 1889). Maerkel (1841, 1844) compiled the first list of known myrmecophilous arthropods, and counted 284 species, including 274 beetle species. Fifty years later, Wasmann (1894) estimated that at least 1246 species of arthropods are known to be associated with ants, with 993 of those species being beetles.

Since 1894 Wasmann and Escherich (1897) predicted that at least 3000 beetle species are associated with ants. The behavioral and morphological diversity observed in myrmecophiles was described in some detail by Wasmann (1894). He noted that various

9 groups of myrmecophiles exhibited certain behavioral characteristics, many of which seemed to be similar. Wasmann attempted to group the various myrmecophiles, especially Coleoptera, into distinct behavioral categories. Since Wasmann’s initial proposed terminology, successive authors have attempted to restructure or redefine his system; however, in spite of the various proposed schemes (Wheeler 1910; Donisthorpe

1927; Akre & Rettenmeyer 1966; Kistner 1979; and Franc 1992) Wasmann’s is still widely used to define myrmecophilous interactions and has been applied to non- myrmecophiles as well. Silvestri (1903) used identical terminology to define the associations between termites and their collembolan guests. Most recently, Hölldobler &

Wilson (1991) used and essentially promoted Wasmann’s classification as the best way to describe the numerous associations found among all known myrmecophiles,. Since then, other authors have attempted to use the same system for Slovakian myrmecophiles (Franc

1992), the large family Scydmaenidae (O’Keefe 2000), and even the small hive beetle that is predaceous on honey bees (Ellis & Hepburn 2006).

2.2.2. An overview of myrmecophilous categories

Wasmann (1894) introduced the terms “synecthrans” (persecuted guests),

“synoeketes” (tolerated guests), “symphiles” (true or symbiotic guests), “ecto- and endoparasites” (parasites on ant bodies), and the “trophobionts” (those that feed ants with honeydew secretions). The synecthrans are classified as those beetles that live in the vicinity of host nests, but only prey upon specific species of ants on raids and migrations, or more specifically, those that constantly move brood and nest materials from one

10 temporary nest site to another. The synecthran classification is limited largely to relatively small Staphylinidae, which usually bear defensive glands on the terminal abdominal segments, and are able to either ward off ants in defense, or “confuse” ants into submission before they are eaten during raids. Similar to Wasmann, Paulian (1948) used the term “les suivants” or “the followers” for similar groups of Staphylinidae associated with army ants in the genera Dorylus and Anomma. Kistner (1979) also suggested the use of “non-integrated” species to define this kind of interaction, given that they do not inhabit the nests themselves.

Wasmann’s second group, the “synoeketes,” includes myrmecophiles that are treated indifferently, and are tolerated rather than attacked by ants like the synecthrans are. The same term was used by Janet (1897). According to Wasmann, they typically are neutral in odor, small in size, move slowly, and are described as having a peculiar body shape, although the shape was not defined by Wasmann. The synoekete category was created solely for subdividing specific staphylinids that closely resembled “typical” non- myrmecophilous members of the family. Wheeler (1910) noted that the synoeketes presented the most diverse group of myrmecophiles and further proposed four subcategories to better define the various kinds of synoeketes associated with ants, namely:

a) the “neutral synoeketes,” which ignore hosts but live on nest materials, refuse

piles, etc.;

b) “mimetic synoeketes” that mimic ants;

c) “loricate synoeketes” that are tear-drop shaped, and therefore hard to capture or

bite by an ant;

d) “symphilloid synoeketes,” which resemble true guests, but “have not yet achieved

perfection; “ however, perfection is never defined and is assumed to describe

those myrmecophiles that are integrated into the ant nest (symphiles)

In addition to the categories above, Wheeler (1910) also included “myrmecocleptics” to denote those which snatched food from ants, a term also adopted by Janet (1897).

Paulian’s (1948) term “les clients” or ant clients includes all myrmecophiles that frequent debris piles and exploit ant bodies or excrement, as well as those that prey upon the insects that are attracted to these items, and is thus synonymous with synoeketes.

The third category was recognized by Wasmann and also by Wheeler as the “symphiles,” or true guests, and is exclusive of beetles that are accepted into nests and integrated into the social life of the ant colony. The level of integration has never been defined clearly, and symphiles vary widely in their behavior. The majority of authors including Wasmann and Wheeler saw symphily as the extreme form of myrmecophily, and the last “phase” reached by myrmecophiles as they interacted with ants. They are known to perform various functions, although the majority is known to beg for regurgitated food from adult ants, or being generally accepted as part of the colony. Symphiles have also typically been defined as having obvious morphological adaptations, particularly tufts of yellow setae, known as trichomes (Alpert 1994, Kistner 1979) that are attractive to ants. Janet used a different term for “symphile,” and instead adopted “myrmecoxeny” as a “special

12 kind of symbiosis,” i.e. one that implied a mutually beneficial interaction. He also established the term “hamabiosis” to denote the living together of two species for any purpose, whether beneficial or parasitic; however, the term was never again used by any other author, most likely because it failed to define any specific kind of interaction.

Paulian’s “les associes,” or the associates, includes all species that are closely associated with ants, and those which are dependent on the ant colony for survival, and is synonymous with the symphile category proposed by Wasmann. Similarly, Kistner

(1979) proposed using the term “integrated inquilines.” This category includes any associate that lives in the same nest as its host, or shares some obligatory or permanent association. He further defined obligate associates or “symbionts” as having four discrete criteria. In order to be considered a symbiont, a species had to fit at least one of the following conditions:

a) It must be repeatedly captured with a definite host;

b) It must bear morphological adaptations that could imply an association;

c) It must have known habits in relation to a host species;

d) If behavior or association isn’t known, it must be morphologically similar to a

species with similar habits and associations with the same host.

Wheeler (1910) additionally suggested a category to define those organisms that feed on

particles within the saliva that cover ants, specifically for myrmecophilous crickets and

Thysanura; however, no Coleoptera are known to act in this way.

The fourth category proposed by Wasmann, and accepted by Wheeler (1910), as well as by Janet (1897), includes ecto- and endoparasites, largely referring to the mites, which feed on exudates or haemolymph from ant hosts. Janet included what he considered to be a second group of parasites, specifically those that use ants to be transported between colonies, the phoretic mites, although no successive author distinguished phoretic mites from parasitic ones. The only coleopterous ectoparasite belongs to the genus Thorictes in the family Thorictidae, and is classified as an

ectoparasite because it is typically found only on the antennal bases of ants (Wasmann

(1895), Wheeler 1910), where it likely feeds on food particles or liquids on the ant head.

The fifth category, which is limited strictly to aphids and lycaenids, includes the

“trophobionts”, or myrmecophiles that supply ants with honeydew in exchange for

protection from their hosts. Wasmann and Wheeler recognized this category as separate

of the symphiles, based primarily on the fact that they do not live within ant host nests,

and because ants actively seek out aphids and lycaenids instead of the other way around.

Similar views have been adopted by other authors, particularly Janet (1897) and

Donisthorpe (1927). Janet took it a step further and excluded lycaenids and aphids

entirely from his classification of myrmecophiles, noting that the relationship was

initiated by ants and therefore contrasted with “ant loving” behavior implied in the term

myrmecophily. Similarly, Donisthorpe (1927) used the terms “extranidal” guests to

denote those that occur and interact with ants outside the ant nests. He suggested that

“intranidal” guests are unique, as they occur only within an ant colony, and actively seek

out ants. Donisthorpe noted that “intranidal guests” exhibit “myrmecophily in its truest

14 sense.” Donisthorpe included all guests that use nests for food, shelter, or protection, whether they are treated indifferently or with hostility. The first four of Wasmann and

Wheeler’s categories were placed into Donisthorpe’s “passive guests” category, including what he classified as the true guests (symphiles), tolerated lodgers (synoeketes), hostile persecuted guests (synechthrans) and all ecto- and endoparasites. Donisthorpe also listed a separate category, which he named the “myrmecophags” or predators of ants.

Akre and Rettenmeyer (1966) proposed a scheme that differed entirely from those of any other author. Their work was focused mostly on staphylinid guests of the Ecitonini

(army ants) and used a combination of morphological and behavioral criteria to redefine myrmecophilous interactions. Their new scheme was created primarily because they suggested that the typical behavioral categories presented by Paulian (1948) and the various works by Wasmann are often placed into discrete classes without any knowledge of their true behavior.

They grouped known myrmecophiles into three categories. First, they distinguished the defensive species that were tear-drop shaped (limuloid forms). These limuloid guests parallels the “loricate synoeketes” suggested by Wasmann and Wheeler as part of the synoeketes. In addition, they recognized the generalized species that bore characters typical of most members of the Staphylinidae, and lacking obvious morphological modifications. They also classified the specialized species that either mimicked ants or those with distinct morphological adaptations to a life with ants.

Generalized and specialized species were further distinguished by lists of specific ethological data that won’t be explored here. What should be noted of their system is that

15 ant mimics are considered to be specialized rather than included in the more generalized, non-integrated synoeketes of Wasmann.

2.2.3. Problems with the proposed classifications of myrmecophily

Several authors have discussed the difficulty in accepting any one existing categorical scheme for myrmecophiles (Hölldobler & Wilson 1991, Kistner 1979). The first issue is that many of the proposed classifications are based on singular taxa or restricted geographic areas. For example, the entire system proposed by Paulian (1948) can be applied only to staphylinid beetles that are closely associated with two European genera of army ants in the subfamily Dorylinae. Akre & Rettenmeyer also based their system on staphylinids. Franc (1992) created a similar classification based solely on the

Slovakian myrmecophiles, although he adopted and made slight adjustments to

Wasmann’s (1894) categories, and his attempts at classifying Coleoptera were focused on identifying trends of endangerment of the “symphilous” types of beetles. The fact that several behavioral classifications have been created for myrmecophilous Staphylinidae illustrates the great diversity in associate-ant interactions that exist within the family, and suggests that it may be useful to use some of the previously proposed behavioral classes for Staphylinidae if it provides insights into their evolution; however, in attempting to apply the terms to other taxa none of the systems work very well.

In other cases, the proposed classification schemes are so broadly defined, that different types of associations can be included in a single group. For example, the very commonly used term “synoekete,” which was used by nearly every author after

Wasmann, is widely applied to many Coleoptera that vary greatly in their biology and in

16 interactions with respective ant hosts. Wheeler’s attempts to further subdivide the synoeketes into four different classes, placing potentially every kind of ant-associated beetle within the group, including the many beetles that are ignored by ant hosts, the numerous genera that feed on debris in refuse piles, several Staphylinidae that are mimics of ants, and those that resemble but are not really “true guests.” In Wheeler’s attempt to capture this diversity of behaviors and even morphology, it appears as if each type is mutually exclusive. For instance, ant mimics, which Wheeler placed in their own category, actually are ignored by ants and may feed on debris in refuse piles, a behavior that is classified separately from the mimic category. Wasmann suggested that mimics are typically not integrated into the ant nest and may be mimicking ants to escape predation by birds. This proposal seems valid, but still fails to solve the problem of successfully placing the mimics into any one category.

Most recently, Ellis and Hepburn (2006) unsuccessfully tried to place the small hive beetle into categories proposed by Wasmann (1894), Wilson (1975), and even

Kistner (1979), but noted that, depending on geographic range, whether the beetles are introduced or occurring naturally, or depending on the level of predation exhibited by the beetle, its association with bees is too complex and conditional to prescribe the beetle to a specific category.

In Hölldobler and Wilson’s (1990) list of myrmecophiles and their respective interactions with ants, much of the information needed to describe these interactions is cursory or completely missing. In the list of Coleoptera associated with ants, nearly half

(18) of the mentioned families are completely unknown behaviorally. In addition, many

17 are presumed to interact with ants in a certain way depending on what is known about a close relative. For example, the scarab genus Stephanuca was recently documented to be associated with ants, although the observations only indicated that beetles land close to or near plants that were covered with ants, and no beetles were ever collected in an ant mound (Paulsen 2002). Paulsen suggested that Stephanuca is probably associated with ants, as a close relative, Euphoria inda , has been found to be carried into ant nests for the

purpose of laying eggs in debris inside the ant mound (Wheeler 1910).

Another problem with adopting distinct sets of terms for myrmecophiles is that

behaviors vary greatly, even among closely related taxa. The best example of

behaviorally divergent Coleoptera has been documented for the genus Cremastocheilus.

This North American genus is presumed to be exclusively myrmecophilous, and all

known species bear conspicuous trichomes that would indicate a “symphilous” habit, if

using the terminology of Wasmann. Most Cremastocheilus species have abundant ant-

host records, but little is known about behavior, except for a few species. Alpert (1994)’s

experiments on host acceptance concluded that behaviors are highly variable within the

genus, and a phylogenetic analysis of the genus also suggests that even within very

closely related, morphologically similar species, behaviors are highly variable (Mynhardt

& Wenzel 2010), which brings up the question whether one should assume behaviors

without behavioral data. As an example, two species within the same subgenus (Alpert

1994) within Cremastocheilus , the two related species C. hirsutus and C. saucius , use

very different strategies to gain entrance into an ant mound. C. hirsutus enters

Pogonomyrmex ant nests on its own, while C. saucius feigns death and relies on the ants

18 to carry it into the nest (Alpert 1994). Based on this information, the two species may be classified differently if using Wasmann’s classification and suggests that even closely related species, which exhibit different behaviors, may not necessarily be recognized in the same category. The necessity and use of actually using categories becomes less and less clear as one considers more taxa. Outside of taxa like Cremastocheilus , myrmecophilous interactions are largely lacking for the majority of Coleoptera. If considering all the factors involved in myrmecophilous interactions, it may be more useful to distinguish unique interactions or behavioral factors exhibited by individual myrmecophilous taxa.

The various descriptions used by authors often circumscribe very similar behaviors, and it is obvious that many of these intended groupings of myrmecophiles focus largely on putting names on specific interactions. After examining the various behavioral classes proposed by authors, similar behaviors are often described, and authors often point out similar aspects of such interactions. For example, many authors have used the relative degree of interactions, as well as location of interactions within or even outside an ant nest, and the potential benefits and/or costs implied by different interactions to define myrmecophiles. It may thus be more useful to recognize specific ecological factors, rather than creating names for interactions, which solves the problems of having taxa fit into more than one category.

By considering numerous factors that describe specific interactions among ant hosts and their beetle associates, it also becomes possible to examine myrmecophily in an evolutionary context. For example, if considering a taxon of interest, the use of specific

19 factors (explained below), rather than using a singular term like “symphile,” may provide more information about the evolution of particular morphological structures or behaviors.

Myrmecophily, as a highly complex system, can be broken down into the factors that support the specific interaction between an ant associate and its respective ant host(s).

Therefore, if attempting to make predictions about the evolution of myrmecophily in a taxon of interest, one can explicitly state exactly how particular factors have evolved.

Instead of stating that a taxon is a “symphile” one might include that it utilizes the nests of various hosts, inhabits the inside of the nest (instead of the outside), feeds on brood

(instead of scavenging in refuse piles), etc., which alleviates the problem of having to put a single taxon into a specific category.

Below, I discuss the diversity in ecological interactions that exist among myrmecophilous Coleoptera and separately discuss the use of morphology as means of defining myrmecophiles, even without availability of behavioral data. Because hundreds of beetle genera are known to associate with ants, it is not my goal to discuss specific aspects of all documented myrmecophilous genera or families, although I present examples throughout. Furthermore, the objective of my scheme is not to “pigeon-hole” or limit specific taxa to “bins” or “baskets” of categories, as this has proven to be more cumbersome than useful in practice. Finally, I am not attempting to refute in entirety

Wasmann or other authors’ proposed categories; several of them are useful, and many of their published categorical schemes have provided a great body of significant behavioral information that has inspired the suggested ideas discussed below.

2.2.4. Using ecological data to classify myrmecophilous Coleoptera

Level of integration: Obligate vs. facultative associations

The classification schemes proposed by various authors are not all completely

synonymous, but all appear to fall into two categories, which I’ll define here as obligate

and facultative associations. Wasmann (1890) initially suggested using the “true guests”

and “casual guests” to distinguish between what he considered to be two distinct groups

of myrmecophilous insects. The true guests were defined as associates that live inside ant

nests and interact closely with ants, often aided by morphological adaptations that allow

them to get accepted into the ant colony. In comparison to true guests, casual guests were

defined as those associates that reside near the periphery of the ant nest, and which are

usually treated with tolerance or ignored completely by their respective ant hosts. Ecto-

and endoparasites, which largely includes the numerous species of mites, were also

grouped into this category; however, Wasmann did not designate whether host specificity

or generalist strategies should be separately categorized for mites.

Wasmann (1894) later redefined his scheme by describing interactions in greater

detail. His “true guests” category was renamed as the “symphiles,” while the

“synoeketes” or tolerated guests, are probably the most synonymous with Wasmann’s

initial “casual guest” category, as they remain near the periphery of ant nests and do not

closely associate with ants. Janet (1897), Donisthorpe (1928), Akre and Rettenmeyer

(1966), and Wilson (1971) accepted Wasmann’s categories, sometimes with slight

modifications.

Kistner’s (1979) system, which recognizes “integrated” and “non-integrated” associates is the best defined, and relies less on placing specific taxa into exact and immutable categories. His categories best capture the various associations that occur between beetles and their hosts; however, his system also requires knowing how

“integration” is defined. Integration can occur through chemical means, by which beetles will adopt the chemical signatures of their respective ant hosts in order to be recognized as part of the ant colony. In Cremastocheilus , authors have suggested that when ants lick the brushes of setae called trichomes, ants are immediately passified (Kloft et al . 1979).

The authors also suggested that the beetles must be transferring certain particles to the

ants; however, Alpert (1994) found no such evidence in lab studies. Similar “appeasing”

reactions have been proposed for various Staphylinidae, especially those which are

regarded as “defensive.” The Staphylinidae that are known to follow ants on raids bear

trichomes and defensive glands on their abdomens, both of which are used to subdue ants

and then capture them as prey. In this case, “integration” is poorly defined, because

Kistner did not consider the defensive staphylinid beetles to be part of the integrated

category.

These seemingly obligate predators may not be integrated into the nest, per se, but

rely on ants for survival. I prefer recognizing that these beetles and their association with

ants be recognized by the fact that they have evolved trichomes that are used to associate

with ants. The only difference, and perhaps most important distinction between various

obligate ant associates is that some are accepted into the colony (integrated) and those

22 which rely on ant hosts but do not necessarily interact in such intimate ways with ants

(non-integrated). Kistner’s definition works here, and should be considered.

I would like to propose a similar argument for those organisms which are typified

as being “synoeketes,” particularly those scavengers which remain mostly outside of

brood chambers and feed on detritus, dead ants, or fungus in the outer chambers. While

these beetles aren’t integrated into the social life of ants, they bear modifications that

allow them to avoid attacks by ants. For example, the monotypic tenebrionid genus

Bycrea is obligately associated with the leafcutter ant species Atta mexicana , scavenging

in surface refuse piles of fungus deposited by these ants. The fact that this species is

found nowhere else and exists only in ant nests, and that its flattened and smooth body

shape allows it to be protected, is enough evidence to suggest an obligate association with

ants, even if not directly interacting with the hosts. This idea also follows with Kistner’s

(1979) suggestion that any long-term association that is indicative of some co-

evolutionary process should be considered, although my scheme relies less on integration

and more on the presence of an obligate association, whether directly with ants or only

peripherally so. If using integration as a factor, one often has to make assumptions about

how tight the interaction is, and biological information is largely lacking for the majority

of taxa, while collection records often indicate the reliance of species on ant nests as

habitat. I also propose including taxa such as Euphoria , the scarab that only uses ant nests to lay overwintering eggs. Those beetles that are limuloid or “tear-drop shaped” (various

Staphylinidae) and even those that are rounded (various genera of histerids) and avoid

23 ants are included here, even though they don’t bear trichomes, as all are known only from ant nests and from no other natural habitats.

While I do not claim that these beetles are as strongly associated with ants as those that bear very distinct morphological modifications and which are actually integrated into the ant colony, I am including them here because of their presumed reliance on ant nests for survival. Kistner noted the difference between general

“adaptation” to the colony and social integration; I agree that these two examples suggest different degrees of interaction, but since I am not proposing that each myrmecophilous taxon be placed in a single category, my use of “obligate” and “facultative” will serve this purpose. Throughout, I will use Kistner’s term “integrated” to denote those myrmecophiles that are known to be accepted by ants as members of the colony; however, “obligate” will refer to any association in which the myrmecophile uses the ant nest for at least one life stage. Furthermore, the level of integration, whether associates are integrated into the colony, or whether they remain in the periphery of the ant nest, often relies on other factors, including food and morphological or behavioral adaptations.

These factors should be considered and discussed if known, and are outlined below

Interaction initiation (host vs. associate)

Janet (1897) based his entire classification scheme on whether ants seek out their associates, or vice versa. He considered only those organisms which initiated interactions with the host as “true myrmecophiles,” because it fits with the “ant loving” definition of myrmecophily. Donisthorpe (1927) also distinguished between these two kinds of

24 interactions. Wasmann’s (1894) initial classification, in which he separated the trophobionts (honeydew secreting insects) from other myrmecophiles also follows with those of Janet and Donisthorpe. I am choosing to consider this factor of myrmecophilous associations in my system, because the suggestions by Janet, Donisthorpe and Wasmann to separate these types of associates from those that actively seek out ants present an effective way of defining how ants actually interact with these hosts. The only problem that arises here is that it becomes challenging to designate when true interactions are initiated. For example, in cases where beetles, such as the “synecthrans,” follow ants on raids, ants may approach the predaceous beetles in order to protect the migrating brood material. Beetles, however, use defensive glands to ward off ants, after which certain ants may be captured as prey. The initiator of this interaction is unclear; however, based on morphological modifications in those beetles, including for example the staphylinid beetle Xenodusa , it is apparent that the beetles have evolved adaptations in order to lure and feed on ants.

I am following Kistner’s suggestion here, so that those organisms which indicate obvious modifications in order to interact with ants are considered to be myrmecophilous.

Since there are no beetles known to exude honeydew, none are considered to be true

“trophobionts;” but some are known to engage in the exchange of fluids with their ant hosts. No experimental evidence exists that suggest nutritive substances are fed to ants. In all “trophobiont” cases, ants are attracted to their associates, as is the case for aphids and lycaenid butterfly larvae; the same attractiveness does not occur in systems where beetles

25 and ants are exchanging fluids; it is clear, instead, that the beetles are using ants for food, a behavior that is usually followed by the beetles feeding on ant brood.

In some cases, such as those where beetles are ignored or tolerated by ants (the so-called synoeketes), it is more challenging to identify the initiator of contact or interaction. Synoeketes are typically “defensive” in form, and are able to either run away or tuck appendages upon contact with an ant. In this case, there is no direct interaction, and neither ants nor associates are attempting to interact with the other party. Instead, these types of myrmecophiles can be distinguished from those that come in direct physical contact with ant hosts. It may also be the case where neither ant host nor associate is actively seeking out the other, so that associations are accidental. It is possible that these accidental associations could eventually lead to or evolve into intimate interactions; an assumption that is commonly made for myrmecophiles, but this is discussed later in the “Evolution of Myrmecophily” section in this chapter. I am not attempting to separate these two behavioral distinctions, because of lacking behavioral information for the majority of species; rather, morphological interpretations become more useful (see morphology section).

Effect on ant hosts and associates

The relative cost or effect on ant hosts have rarely been documented, although certain assumptions can and have been made, depending on the interaction. Nor have the relative costs and benefits to ants been addressed in any proposed classification scheme; instead, the focus seems to be on the associates. Thus far, little information exists that

26 focuses on benefits for ant hosts; however, some authors have posited that the presence of various scavenging insects, which includes many “synoekete” generalist or facultative beetles, may be beneficial to the condition of the ant colony. Scavenging ant associates may indirectly benefit the ant colony by consuming or breaking down waste materials that may harbor pathogens, and experimental evidence shows that ants have sophisticated labor division systems that help them dispose of waste away from the ant nest (Hart &

Ratnieks 2002, Steiner 2004). In addition, the grooming behaviors exhibited by various beetle species may have some advantage for the ants, perhaps to remove bacteria or other materials from the ants’ integument.

Some interactions between associates and ant hosts appear to be more or less neutral, at least on the part of the host. If considering all the “synoeketes” mentioned by various authors, many of the beetles included in this category are scavengers that hardly interact with ants, even though they may be obligate ant nest inhabitants. Scavenging beetles, and many other arthropods, are not known to negatively affect ant hosts, although they feed on various materials gathered by or discarded by ants, including seeds, dead ant bodies, and fungi (Wasmann 1894), and as mentioned earlier, they may actually benefit the hosts rather than negatively affect them. In the singular example of Thorictus , a beetle that latches on to the antennal scape of ant hosts, its potential effect on ants is unknown

(Wasmann 1895). Phoresy, although uncommon among beetles, also has no proven negative effect on ant hosts, unless phoresy negatively impacts the ability of ants to forage or complete other tasks within the ant nest. The staphylinid beetle genera,

Paralimulodes wasmanni and Doryloxenus use ants for transport and attach to their hosts

27 with specialized setae, especially the former, which attaches to the head and venter of ant hosts in a similar fashion as mites (Wilson et al. 1954; Kistner 1971). P. wasmanni also

uses specialized mouthparts to scrape food particles from the cuticle of ant hosts and is

therefore not a parasite. No negative effects have been recorded for this species’

association with ants.

Negative effects on ant hosts are more common than beneficial or neutral effects,

based on the number of predaceous beetles associated with ants. Even the most obligate

ant associates may be predaceous, as are many entirely non-integrated (synecthran)

species. The only existing studies that have aimed to determine potential effects of ant-

associate interactions have been conducted by Hölldobler (1971). Hölldobler determined

that when beetle larvae beg ant adults for liquid droplets of food, they often “out-beg” ant

larvae. Their ability to be adopted and successively beg for food may have a negative

effect on the existing ant larvae. Several authors have suggested that the amount of

begging performed by beetles results in the production of “pseudogynes,” or sterile ant

queens, due to the lack of liquid food required to develop into fully functioning queens.

Since ant colonies rely on queens to produce worker ants and to found new colonies, this

type of interaction definitely presents a high cost to ant hosts (Wheeler 1910, Wilson

1971).

Proposed classifications often discuss how associates are treated by their ant

hosts, although costs and benefits to associates, similar to those of their hosts, have not

been studied in any detail. What is known is that ant associates are variably affected by

their hosts. The “synecthran” category of Wasmann indicates “persecution” of

28 staphylinids outside the ant nest. There seems to be a trend suggesting that those beetles which live inside the ant nests, whether near the periphery, or within brood chambers, are treated with less hostility. In Wasmann’s terminology, they are “tolerated.” One might consider this to be a neutral interaction, as beetles either ignored or tolerated, depending on body shape or the ability to outrun hosts (Wheeler 1910). Positive impacts on ant associates are rare; however, for the highly integrated staphylinid genus Adranes , beetles

are fed by ant larvae via the exchange of liquid food. Other beetles are known to interact

directly with ant adults or workers, instead of larvae. Other staphylinid beetles, and

potentially other families, such as Gnostus within the Ptinidae, are fed liquid food, which

may be a benefit to the beetles; however, these close interactions with ants or larvae

allow beetles to feed on ant larvae without being detected. Whether beetles actually

require liquid food or whether such resources are beneficial is not known, and indicates a

large area of study that has been little explored.

2.2.5. Using morphology to classify myrmecophilous Coleoptera

Because most myrmecophiles are rare in collections (Wheeler 1910) and are usually

difficult to observe in nature, myrmecologists and coleopterists commonly rely solely on

morphology to understand potential interactions among ants and their associates. It is also

evident that for every proposed behavioral scheme, authors typically refer to morphology

to justify or support specific behavioral interactions (e.g. the “tear-drop shaped”

synoeketes). Given that morphology may be the only information available to define

myrmecophilous interactions, a lot of what we know about myrmecophiles depends on

29 understanding morphology and its potential use in defining myrmecophilous insects, especially Coleoptera.

The body parts often modified in myrmecophilous Coleoptera vary greatly by degree of modification. Many of these modifications are evident throughout the order, and usually in the same body parts or regions. In some cases, morphological adaptations occur as “suites,” or combinations of characters that include modifications of antennae, body shape, leg shape, body color, and/or the presence or absence of glands and trichomes. In other cases, the “suites” of morphological adaptations vary, so that the antennae are not modified, but trichomes and glands are present. The great diversity in myrmecophilous Coleoptera, in terms of both biological interactions and morphology, will be evident with some of the examples listed below. Perhaps the most important point here is that those characters defined as being “myrmecophilous” in nature are found only among ant-associates. I describe the various unique myrmecophilous modifications known among Coleoptera; however, I will make note of some similar modifications, particularly related to mimicry, that are known for interactions between beetles and termites, as well.

Body shape

Akre & Rettenmeyer (1966) examined different body shapes of Staphylinidae, and suggested that specific types of morphology could be directly linked with certain behaviors. They used Wheeler’s (1910) term, the “loricate synoeketes” or tear-drop shaped beetles to define those beetles that are able to defend themselves by tucking in

30 legs and antennae, and being unable to be picked up by ants. Their distinctions between

“generalist” and “specialized” beetles were also described by using morphology.

Generalist staphylinids have no obvious morphological adaptations and look just like non-myrmecophilous Staphylinidae. In contrast, specialized taxa should be unique in morphology and indicate myrmecophilous interactions. Nagel (1979) also used morphology to distinguish between “defensive-type” Paussine carabids, and “symphilous types.” Defensive types, which were also described briefly by Wasmann (1894) as the

“trutztypus” and in more detail by Kistner (1971) are mostly recognized as those beetles that can tuck in appendages to avoid attack by ants. Kistner (1971) suggested that defensive myrmecophiles are characterized by a “limuloid” body shape, named after the beetle family, Limulodidae. Beetles that approach this body form bear reduced legs and antennae, overlapping or shield-like body regions, reduced head size, and the development of lobes or “shields” that protect the joints of appendages. The thickening of chitin is also often associated with this body form. Akre & Torgerson (1969) did studies on one of these limuloid beetles in the genus Vatesus , another staphylinid myrmecophile associated with army ants. It has a unique burying behavior, which allows it to go unnoticed by ants; however, it is attacked when discovered by ants. Akre & Torgerson claimed that the genus is fully integrated because of its ability to go unnoticed, and to feed on ant brood in the lab; however, Kistner suggests that its morphological adaptations only indicate an adaptation to the ant nest (an obligate associate, in my definition), rather than being integrated into the ant colony. Kistner’s independent studies on various other genera that bear this “limuloid” shape, such as the genera Phyllodinarda , Mimocete ,

Doryloxenus , and Annomatoxenus , all associated with legionary ants, are very commonly attacked, but are able to escape from ants by their unique rounded and shielded body form (Kistner 1965, Kistner 1976). In staphylinids associated with the army or driver ants, their body form typically resembles that of their ant hosts, although Wasmann

(1894) suggests that this may help to prevent the beetles from being eaten by birds during raiding activities.

Antennal modifications

Some of the most obviously modified parts in myrmecophilous beetles are the antennae, which take on a variety of shapes and are often highly reduced (usually due to fusion of individual segments). Wasmann (1890) and Wheeler (1910) have proposed that particular shapes of antennae can be used as predictors of the beetles’ respective interactions with ants. For example, sickle-shaped or “ant-like” antennae are supposedly predictors of the grooming actions performed on ant hosts by certain beetle associates.

Some myrmecophilous staphylinids, particularly those that associate with army or driver ants, often bear antennae that resemble the geniculate shape of ant antennae (Akre &

Rettenmeyer 1966). In contrast, flattened or paddle-shaped antennae may be used by ants to pick up and carry beetles into or around the ant nest, often to the brood chambers.

Similar to most other body parts, the correlation of these supposed predictions have never been tested in a phylogenetic context, largely because behavioral information is lacking for the majority of beetles that live as inquilines deep within ant nests.

The reduction of antennomeres is also common in many myrmecophilous

Coleoptera, especially for the beetles that are presumed to be what Wasmann called the

“symphiles.” However, for the obligate staphylinid genera, Lomechusa and Atemeles this doesn’t appear to be the case. These two genera are two of the best studied by Bert

Hölldobler, and both are known to enter ant nests, beg for and be fed regurgitated fluids by ants, and be adopted fully into the ant colony. Both species’ larvae are also fed by ants as if they were ant larvae, while the adults often feed on ant brood. Modifications in antennae may be unnecessary for these genera because they are often cited as having strong chemical signatures that allow them to get accepted into ant nests without much difficulty (Hölldobler 1971). However, the same argument doesn’t hold for many other

Coleoptera that have glands or associated trichomes. Nearly every known beetle species that lives within, and is accepted into, the ant colony does so with glandular modifications; and the majority of those inquilines bear reduced antennae.

The myrmecophilous staphylinid genera in the subfamily Pselaphinae, Adranes and Claviger can have anywhere between 2-6 antennal segments, as compared to the typical 11 segments in non-myrmecophilous taxa. All known Paussinae, a subfamily within the Carabidae, are known to bear variably modified antennae, both in size and shape. Nagel (1979) suggested that Paussines could be defined as either “defiant” or

“symphilous,” so that the former has simple antennae that can be brought close to the body to avoid ant attacks, and the latter has modified antennae that are filled with glands used to interact with ants. Also unique in this group is that the pedicel, one of the basal segments of the antennae, is reduced, and is predicted to become progressively vestigial

33 in more derived paussines, and led to loss of the Johnson’s organ that is used for mechano-reception in insects. The same level of reduction has not been documented in other myrmecophilous Coleoptera. In beetles that appear to be feeding on debris and not interacting directly with ants, antennae remain largely unmodified, which supports the hypothesis that antennae play an important part in ant-beetle interactions, and may even be used as predictors of specific behaviors.

Mouthparts

The mouthparts of many myrmecophilous beetles are often reduced, particularly of the beetles are known be fed by ants via trophallaxis (Wheeler 1910). The reduction in mouthparts has evolved in all known myrmecophilous Ptinidae (Lawrence & Reichardt

1969), and in other taxa, such as Cremastocheilus , the mouthparts are hidden and

protected by an enlarged mentum, which completely conceals all the mouthparts. The

role of the enlarged mentum is not known, but is predicted to protect mouthparts from

predators, such as ants (Alpert 1994). Since closely related, non-ant-associated genera

also bear large menta, it can be assumed that the mentum is modified for another

function, and not for a myrmecophilous habit.

Trichomes

Perhaps the most uniform and unique morphological adaptation found only among myrmecophilous Coleoptera is the presence of trichomes on various body parts.

Trichomes appear to be most common on the prothorax ( Cremastocheilus , most Ptinidae,

Histeridae, Paussinae), although they can be found on the elytra (Histeridae,

Staphylinidae – Adranes and Claviger ), legs (certain Ptinidae, including Fabrasia ), or abdomen (Staphylinidae – Lomechusa and Atemeles ) of beetles. In fact, the majority of authors suggest that the presence of trichomes can be used as direct evidence for some of the most evolved beetle-ant associated interactions (Wasmann 1890, Alpert 1994, Wilson

1971, Hölldobler & Wilson 1990). Where data are available, beetles that possess trichomes are exclusively, and intimately, associated with ants; and the majority of the trichome-bearing Coleoptera are obligate ant associates, where they directly interact and are usually integrated into the ant colony. Many beetle genera, and even entire families, have been described as closely-associated myrmecophiles based on morphology; however, biological information is rarely available to test these assumptions. What is known is that myrmecophilous beetles can bear various combinations of morphological modifications, some of which are backed up by behavioral information, but the majority of which are not.

Other characters

Other modifications that are typically mentioned, but which appear in many other non-myrmecophilous insects include fossorial (digging) legs in species that are known to live with ants underground (Alpert 1994), and coloration that matches that of the ant host

(Wheeler 1910, Akre & Rettenmeyer 1966). In addition, a highly armored or very smooth integument surface, and even a flattened body shape (similar to the limuloid or

“defensive” body shape) used as a means to defend against ant attacks is considered to be

35 due to myrmecophilous interactions. What is interesting is that the many “synoeketes,”

(Wasmann 1894, 1897, Wheeler 1910, Franc 1992) or “non-integrated” (Kistner 1979) or facultative taxa bear these various characters; only those that are assumed to be very closely associated with ants by being accepted into the colony bear more specialized morphological modifications.

2.3. Evolution of myrmecophily 2.3.1. Overview

Existing studies on myrmecophily often attempt to make statements about the evolution of ant-associated behaviors within taxa. The rarity of myrmecophiles in collections, as well as the challenges to rear them in a laboratory setting, has led authors to rely heavily on morphology, and in some cases, random notes on potential functions of respective morphological characters with regards to myrmecophily. In cases where behavioral data are available, even for a single species within a larger myrmecophilous group, assumptions are often made about how myrmecophily has evolved within that taxon. Currently there are several recognizable patterns that underlie the majority of studies focused on the evolution of myrmecophily. When examining the beetles as a whole, myrmecophily has evolved numerous times in very distantly related taxa and similar patterns of multiple origins of myrmecophily exist even within single families of beetles, including the Ptinidae (Philips 2000), Scarabaeidae (Philips et al. 2004),

Carabidae, etc. Given that myrmecophily has evolved numerous times in many taxa across Coleoptera, many authors have used any existing data to track how myrmecophily

36 informs phylogeny. Described below are a few examples of how information on ant- associated behavior has contributed to general studies of evolution among taxa. I present a) the use of larvae as indicators of the evolution of myrmecophily; b) the suggested evolution of myrmecophily from defensive to “integrated” or, based on my preference, obligate myrmecophiles, and c) general patterns and future work suggested regarding the evolution of myrmecophily.

2.3.2. Stages of myrmecophily

Wasmann (1894) was the first author to suggest that the various myrmecophilous interactions occur in phases, with each phase indicating part of a linear progression towards a gradual increase in complexity toward the most highly evolved (symphilous) myrmecophiles. When Wheeler (1910) subdivided the synoekete category, he included a group of myrmecophiles that had “not yet achieved perfection,” i.e. those that appeared to be on their way towards full obligate associations with ants. Wasmann’s idea suggests a directional and even purposeful shift towards “true” or obligate myrmecophily, with the

“highest” forms being those myrmecophiles bearing trichomes and being accepted into the colony. The idea that myrmecophily becomes more complex over time has influenced many modern studies, especially when attempting to examine potential phylogenetic trends of myrmecophily among related taxa. Thus far, no studies exist which have been able to fully examine the existence of such transitions among myrmecophiles, largely because behavioral information is lacking. What is known is that myrmecophily is a complex phenomenon that involves various types of interactions, some of which rely on

37 different levels of integration into the ant colony, but none of which indicate discrete steps towards a “perfect” myrmecophile.

In Alpert’s (1994) examination of the genus Cremastocheilus , he attempted to

differentiate between two hypotheses initially proposed by Hölldobler and Wilson

(1971), regarding the evolution of myrmecophily within the group. Hölldobler and

Wilson suggested that different species within Cremastocheilus were either at different

stages, similar to Wasmann’s phases, in evolving with ants, or that species had radiated

and evolved different mechanisms of integration into the various ant host species’

colonies. Since behaviors are variable among very similar species in the genus, and some

species have been shown to be treated with less hostility than others, Cremastocheilus is

one of the examples that make the phases suggested by Wasmann less credible. Instead,

and in the case of Cremastocheilus , for the few individual species for which behavior is

known, it appears that species adopt different strategies to be accepted into, or even be

removed from an ant colony, the latter of which may be to find mates outside the ant nest

(Alpert 1994). Before Alpert’s work, Wheeler (1910) suggested that Cremastocheilus is a

degenerate symphile, and has, in a sense, devolved from being a true symphile to being

less accepted in ant colonies (a synoekete). Given that behavioral data is known only for

a few species within the genus, making inferences about trends in evolution within the

group have to be done with great caution, but may be possible with additional data. For

other taxa, for which behavioral information is completely unknown, Wasmann’s

evolutionary phases are not clear, although authors have attempted to use morphological

and even behavioral characters to test whether these phases are paralleled in phylogenies.

Danoff-burg’s (1994) results of a phylogenetic study of two groups of sceptobiine staphylinid genera (one living within the nest and one living peripheral to it) suggests that phylogenetic patterns are often reflected by ecological and behavioral differences that may be due to host specialization and geographic isolation during speciation. Danoff- burg also hypothesizes that a common ancestor of the two tested beetle genera likely led to two beetle clades that specialized ecologically in different parts of the ant nest, and may have led to speciation and therefore different integration strategies. His study also suggests that there are not necessarily any trends towards greater complexity; rather, different levels of integration into the ant colony are due to other ecological factors.

In other beetle groups, such as the spider beetles, myrmecophily has evolved numerous times in several unrelated genera within the family (Philips 2000). In Philips’ study, which included three of the eight known myrmecophilous genera, each has evolved independently, an idea supported by the great variability in morphological characters among these taxa. For example, in the genus Fabrasia , trichomes are found on the hind femora, and antennae lack any modifications. Gnostus bears trichomes on the pronotum, and bears highly reduced antennae that only have three antennomeres, as compared to typical, non-myrmecophilous spider beetles. Based on Philips’ study and my work on the family, myrmecophily has arisen five times and has radiated in Old World groups found in Australia and southern Africa (Chapter 4). Without corresponding behavioral data, except for four species Gnostus floridanus (Thomas et al . 1992) ,

Enasiba tristis , E. microcera (Clark 1923) and Diplocotidus formicola (Wasmann &

Brauns 1925), all of whom are groomed by ants, little can be said regarding transitions

39 from non-myrmecophily to true integration within ant colonies. Based on morphology it is assumed that all myrmecophilous Ptinidae are obligate myrmecophiles. When one considers the placement of trichomes in unrelated myrmecophilous spider beetles, especially given the current phylogeny (see Chapter 4), it is clear that myrmecophily has not evolved in phases in this family, at least not in the New World taxa. In Australian and

South African genera, which all share a common ancestor (indicating a single origin of evolution within the group), morphology is still highly variable, at least with regards to antennal characters. In addition, trichomes are variably produced in different taxa within the Old World taxaIn the Australian genus Polyplocotes trichomes are highly reduced to nearly absent (Lawrence & Reichardt 1969, Bell & Philips 2009), although other typical myrmecophilous modifications are present.

2.3.3. Larvae as indicators for evolution of myrmecophily

Many authors have pointed to larvae to make inferences about the evolution of myrmecophily. Perhaps the most well studied group includes the Carabidae. In studies of the myrmecophilous carabids within the subfamily Paussinae, authors have found that much information exists, at least with regards to morphology, within the larvae of myrmecophilous beetles. Recently, Di Giulio and Moore (2004) suggested that myrmecophilous larvae within the Paussinae must have evolved myrmecophily before the adults did, which indicates a mode of transitioning from the typical predaceous carabid to fully-integrated myrmecophilous carabids. Paussine larvae are unique in bearing flattened disks on the tip of the abdomen, which are used to plug holes in the ground. Pores in the

40 terminal disks release substances that are attractive to prey. The authors suggest that using this “ambush” feeding strategy is evidence of a pre-adaptation for myrmecophily within the group. This is perhaps the only example where ant-associated beetle larvae are active predators; however, no behavioral data exists for any of the 300-plus species within this group (Di Giulio 2008).

For the scarab tribe Cremastocheilini, authors have promoted similar ideas that associations with larvae may have led to obligate associations with ants. In

Cremastocheilus , larvae do not interact closely with ants and feed on detritus in the

periphery of the ant nest, but a peculiar behavior has been documented for larvae of the

genus. They are known to “rear up” and strike in response to adult ants, but this indicates

a defensive behavior rather than the active predator behavior of the paussines.

Cremastocheilus larvae have never been shown to feed on ants; however, in certain species in Euphoria , a genus relatively closely related to Cremastocheilus , the larvae can be found feeding on decaying organic material within the thatches of Formica ant host

nests, even without the presence of ants. Ratcliffe (1976) found that larvae were still

present in long-abandoned nests and were feeding on debris without the presence of their

hosts. This suggests that the reliance of larvae on ant nests may be evidence for a

transition from flower-feeding adults to eventual associations with ants, from casual (as

in Euphoria ) to obligate associations in Cremastocheilus . In addition, closely related

beetles in the tribe Cremastocheilini have been documented feeding on other insects,

specifically homopterous insects, such as aphids, in the order Hemiptera. Since

homopterous Hemiptera are often closely associated with ants by means of trophallaxis, it

41 has been suggested that cremastocheilines have moved from feeding on other insects, to feeding on ants in Cremastocheilus.

In another case, larvae of the staphylinid genus Atemeles are accepted into the colony by ant hosts, probably by chemical mimicry of the ants’ chemical signature

(Hölldobler 1971). Ant adults tend the beetle larvae as ant larvae, which beg and are fed by ants as if they were ant larvae. The larvae proceed to feed on ant larvae. This is one of the only myrmecophilous beetles known to be integrated into ant mounds as both larva and adult. The adults are able to be fed by ant adults in the same way, although also with the additional of “appeasement” or “adoption” glands, according to Hölldobler.

Larvae seem to hold much information and may indicate interesting trends in myrmecophily that may not be directly evident for adults. The interactions among beetle larvae and ants might provide additional insights into the level of integration adopted by myrmecophiles, but given that few myrmecophilous beetle larvae have been described

(De Giulio et al. 2008) little can be said for the majority of known myrmecophilous species. However, based on available information, it is likely that larvae may be responsible for any potential transitions of taxa from one food source to another over time. Larvae of myrmecophilous beetles may also provide additional information about the evolution of ant-associated behaviors in their adult counterparts, especially with regards to development of glands and other myrmecophilous structures.

2.3.4. Defensive to integrated forms

In many beetle families, authors have noted that the respective taxa indicate transitions from “defensive” forms to “integrated” or, in my terms, obligate forms.

Wasmann initially classified defensive forms as certain synoeketes, based on limuloid body shape, tuckable antennae, etc. Similarly, Akre & Rettenmeyer (1966) suggested that staphylinids could be classified as “defensive,” “generalist” or “specialist” types depending on the level of interaction observed in their behavior. A similar system was proposed by Nagel (1979), who stated that paussine carabids existed either as “defensive”

(trutztypus, according to Wasmann) or obligate (integrated) forms. Both of these studies make the assumption that myrmecophily occurs in phases, similar to those of Wasmann.

For example, Nagel suggests that defensive glands in many staphylinids that are associated with migratory ants (mostly army ants) become reduced in highly-integrated beetles in the group. Those with “loose contact,” such as the staphylinid genus Pella , use

chemical defenses to survive in an ant nest. He also notes that highly derived Paussinae,

which are suggested to be highly derived bombardier beetles, still probably use exploding

glands outside the ant nest, but avoid the use of these glands in the vicinity of ants. In this

system it appears that beetles can be both defensive and an obligate associate, but not at

the same time, which suggests that “highly evolved” or highly derived myrmecophiles

can maintain plesiomorphic traits even in the presence of ants. This may merely indicate

that Paussinae are related to similar defensive types of carabids, but that they are

additionally able to distinguish between ant hosts and other enemies.

Other authors hypothesize that “basal” myrmecophiles are those which are

attacked by ants, and eventually become accepted when engaged in close contact with

43 ants (Geiselhardt 2007, Vander Meer & Wojcik 1982). Vander Meer & Wojcik’s study on a scarab species Martineziana excavaticollis , associated with fire ants in the genus

Solenopsis , also indicates rapid changes from defensive behaviors to being integrated into

the ant colony by use of obtaining the ants’ chemical signature. Close physical contact

with ants, and in some cases the consumption of regurgitated liquids from ants, which are

likely to contain species-specific hydrocarbons, both contribute to the adoption of host

chemicals. Another study claimed that the use of chemical camouflage indicates an

intermediate step between non-myrmecophilous and myrmecophilous carabids. The

carabid genus Siagona captures ant prey and wave captured individuals in the air. It is assumed that the beetle is sprayed and covered in ant chemicals, which would allow it to get accepted into the ant colony to further feed on ants. Since it does not produce chemicals itself, but uses the ants to obtain their specific chemical signature, it is not (yet) a “true” myrmecophile, according to the authors (Talarico et al. 2009). Based on existing carabid phylogeny, the phylogenetic distance of Siagona from the myrmecophilous

carabids, and given that no other carabids between Siagona and the Paussinae are

myrmrecophilous, Talarico et al.’s claims warrant much further investigation.

Other organisms that obtain chemical signatures, but which are not considered to

be true myrmecophiles, are common, and authors often assume that the system of

chemical camouflage may indicate a step towards evolving mechanisms to be fully

integrated into ant colonies (Vander Meer & Wojcik 1982, Witte et al. 2009). Thus far,

no studies have tested the validity of this hypothesis, but with ongoing phylogenetic

studies it may eventually be possible.

2.3.5. Summary and future work

The assumption made by many of the above studies is that obligate myrmecophiles indicate a higher level of evolution or that those taxa necessarily bear highly derived characteristics. Using this terminology implies that certain myrmecophiles are less derived, and suggests some kind of grade or scale that exists among ant associates. It is clear that many behaviors exist, and the degree of those respective behaviors are variable and cannot be “contained” in single categories. Thusfar, and given the lack of behavioral and phylogenetic information, the assumption that things evolve to become more complex should be approached with caution. Without behavioral data little can be said for how behaviors or specific interactions with ants have evolved over time.

On the other hand, morphology may be used to make assumptions about the evolution of structures, but since many myrmecophiles bear different combinations or suites of characters related to myrmecophily, making assumptions that behaviors exist based on what appear to be similar morphological characters becomes problematic. A recent study comparing aphids and lycaenids, both of which are phytophagous groups of insects that produce honeydew or sugary substances for their ant hosts, indicated that the lack of phylogenetic information for either group poses difficulties in making claims about how evolution has evolved within myrmecophiles. Among aphids, the level of interaction varies greatly among closely related species, while lycaenids are much more homogenous with regards to behavioral interactions with ants (Stadler et al. 2003). The lack of information, both in terms of behavioral data and phylogenetic relationships among taxa,

45 makes studying myrmecophilous Coleoptera additionally challenging. Continuing phylogenetic studies may reveal step-wise transitions from facultative to obligate myrmecophiles, which would support Wasmann’s hypotheses that myrmecophily occurs in phases, and might indicate increasing levels of complexity. However, since it is known that obligate myrmecophily has evolved numerous times in unrelated Coleoptera, those assumptions are notmet. Within Chapter 3 and 4 I explore and discuss the evolution of myrmecophily in two groups of beetles.

Table 1. Behavioral classification and placement by major author

Deboutteville 1948 Wasmann Silvestri 1903 Kistner Behavior Donisthorpe 1927 Paulian 1948 (termitophilous 1800s (termitophiles) 1971 Collembola) Scavengers or predators, Non- Passive/intranidal Accidental/preferred, or ignored or tolerated by Synoeketes Synoicoxeni Les clients/”clients” integrated guests obligate commensals hosts species

Scavengers or predators, Non- Passive/intranidal Les clients/”clients” or Accidental/preferred treated with hostility; Synechthrans Cleptocoxeni integrated guests Les associes/”associates commensals defensive species

Accepted into colony by Passive/intranidal Integrated being groomed, fed, or Symphiles Euxeni Les associes/”associates” Obligate commensals guests species 47 reared

Live on body surface of Passive/intranidal Integrated host, feed on secretions Ectoparasite Parasitoxeni Les associes/”associates” Obligate commensals guests species or food particles

Penetrate body to feed on Passive/intranidal Integrated Endoparasite Parasitoxeni Les associes/”associates” Obligate commensals blood; parasite guests species

Mutualistic relationship; Active/ extranidal Integrated exchange of fluids or Trophobiont Euxeni Les associes/”associates” Obligate commensals guests species materials

Follow ants on migratory Synecthrans - Les suivants/followers - - movements/raids

Chapter 3: Phylogenetic analysis of the myrmecophilous scarab genus, Cremastocheilus knoch

Published as: Mynhardt, G. and J.W. Wenzel. (2010). Phylogenetic analysis of the myrmecophilous Cremastocheilus Knoch (Coleoptera: Scarabaeidae: Cetoniinae) based on external adult morphology. Zookeys 34:129-140.

3.1. Abstract The genus Cremastocheilus (Coleoptera: Scarabaeidae: Cetoniinae) is a myrmecophilous group of approximately 45 species distributed throughout North

America. Authors previously recognized anywhere between two and five subgenera. The first cladistic analysis of Cremastocheilus , based on 51 external adult morphological characters, is presented. The monophyly of the subgenera C. (Macropodina ), C.

(Trinodia ), and C. (Cremastocheilus ) is supported. Cremastocheilus (Anatrinodia ) wheeleri is most closely related to other C. (Cremastocheilus ) species. The three species groups comprising C. (Myrmecotonus ) are paraphyletic with respect to C.

(Cremastocheilus ). Based on examination of the strict consensus of 24 equally parsimonious trees C. (Myrmecotonus ) and C. (Anatrinodia ) are synonymized with C.

(Cremastocheilus ). The pronotum, which bears most of the glands that enable beetles to interact with ants, provides important characters, while characters associated with setae and tomenta are homoplastic. 48

3.2. Introduction Cremastocheilus Knoch is a unique scarab genus that can be recognized by a suite of characters related to its myrmecophilous habit. It can be distinguished from other scarab genera by distinct anterior and posterior pronotal projections or “angles” that bear exocrine glands and associated trichomes (clumps of setae typically associated with glands, see Fig. 1). The pronotal angles are highly variable within the genus, particularly in C. tibialis which lacks posterior pronotal trichomes entirely. Similarly, posterior pronotal trichomes are found in the New World related genus Centrochilus

Krikken (see Krikken 1976) as well as Old World genera Aspilus Shaum and

Lecanoderus Kolbe, although none of these genera have modified anterior pronotal angles or associated trichomes (Krikken 1982). In comparison to related genera

Cremastocheilus is one of the more speciose and probably best studied groups within the tribe Cremastocheilini (Krikken 1984), which includes 51 genera worldwide

(Krikken 1984) and ten in the New World, including Cremastocheilus . There are approximately 45 recognized species, including several subspecies found throughout

North America. As adults, all species are presumed predaceous on ant larvae and, in some cases, pupae, based on collection records and behavioral studies on certain species (see Cazier & Mortenson 1965). Related beetles are also known to be predaceous on other insects, e.g. Pseudospilophorus plagosus Boheman preys on soft scale insects in southern Africa (Buttiker 1955), and Spilophorus maculatus (Gory

& Percheron) from southern India has been documented feeding on membracids

(Ghorpade 1975). It is presumed that related species in the tribe Cremastocheilini

Figure 1. Differences in pronotal angles in Genuchinus (A), and Cremastocheilus (B); arrow indicates pronotal angle

are also predaceous based on the expanded mentum (Krikken 1984). In addition, no genus, except Centrochilus and Old World genera Aspilus and Lecanoderus bear trichomes like those of Cremastocheilus ; however, the presence of associated glands makes Cremastocheilus a distinctive genus within the tribe as well as the scarab subfamily Cetoniinae.

Horn (1879) was the first to suggest that trichomes in Cremastocheilus species are associated with glands that secrete substances somehow pleasing to ants. In contrast,

Wheeler (1908) proposed that pronotal glands emit substances that are irritants that

“distract” ants from attacking more vulnerable organs. Others have proposed that trichomes allow the beetles to gain access to ant nests by rapid diffusion of aromatic substances that would allow beetles to be carried into ant nests as food (Cazier &

Mortenson 1965). In support of Wheeler, Alpert (1994) recently found that ants “lick” the pronotal glands and beetles are subsequently ignored within the brood chambers while feeding uninterruptedly on ant larvae. Given the above scenarios it is possible that different Cremastocheilus species use various means to gain access to ant mounds or be expelled from them. Alpert (1994) has shown that exocrine glands and their associated trichomes vary greatly among species. In addition, he found that clusters of glandular cells are often located underneath or close to external patches of hair called tomenta, particularly in the abdomens of several species. The frontal tomenta which largely distinguish the subgenus C. (Trinodia ) also indicate closeness with glands inside the head of these beetles, but there is no evidence that pores or other secretive structures are associated with these patches of hair. Alpert’s (1994) definitions of various species

groups suggested that ant host, habitat, and position of glands and trichomes are good indicators of relatedness or similarity among different species.

In Horn’s (1879) revision of Cremastocheilus the mentum was used to distinguish

between 17 species known at the time. Mann (1914) created a new subgenus named

Myrmecotonus that would divide Cremastocheilus into two groups based on geographic range and an emarginated mentum (Table 1). Typical Cremastocheilus species bear a mentum that is notched at the base and are distributed throughout the eastern United

States. All other known species are distributed throughout the western United States and northern Mexico, and lack a notched mentum. Mann also suggested that an unusual species described by LeConte as C. wheeleri would belong to C. (Myrmecotonus ) given the angulate, non-emarginate mentum. Noting the variability of mentum, pronotal, and leg structure within the group, Casey (1915) later described 15 new species and two new subspecies. He proposed two new genera including Macropodina, which

was named for distinctive enlarged fore tarsi, and Trinodia , which included specimens

with a distinctive tri-lobed pronotum. Casey also rejected Mann’s (1914) subgenus

Myrmecotonus , noting that most species bear a non-emarginate mentum, which would

put all atypical Cremastocheilus species and other genera in the subgenus. The subgenus

Myrmecotonus has been problematic, due to what most authors would admit is a lack

of synapomorphies or good subgeneric definition. In contrast with Mann’s (1914)

suggestion it was treated as a synonym of C. (Cremastocheilus ) by Krikken (1982), and

was later recognized by other authors as an ill-defined subgenus (Howden 1971). Alpert

(1994) reinstated C. (Myrmecotonus ) due to geographic range.

Casey (1915) also suggested the recognition of one new monotypic subgenus

Anatrinodia for C. wheeleri , based on a transverse, lobiform mentum, but still related to other typical Trinodia by possessing a somewhat similar tri-lobed pronotum. Later,

Cazier (1938) synonymized the genus Macropodina with the genus Cremastocheilus based on what he believed to be few supportive characters for generic status. Cazier also synonymized Trinodia and the subgenus Anatrinodia with Cremastocheilus and suggested that C. wheeleri is an intermediate form between C. (Trinodia ) and C.

(Cremastocheilus ). Similar to Cazier, Potts (1945) only recognized Macropodina and

Cremastocheilus as well defined subgenera, and united Anatrinodia and Trinodia informally into what he called a single “Trinodia group” in Cremastocheilus , following

Cazier’s (1938) suggestion. Howden (1971) also did not recognize C. (Anatrinodia ) but provided no information on the placement of C. wheeleri . It is assumed that Howden’s key would place C. wheeleri in C. (Cremastocheilus ). Krikken (1982) later reinstated

Anatrinodia as a unique subgenus due to its unique pronotum and mentum. Recently,

Alpert (1994) recognized all subgenera, including C. (Myrmecotonus ) and C.

(Anatrinodia ) based on differences in geographic range previously recognized by Mann

(1914).

The aim of this study is to test the monophyly of currently recognized

Cremastocheilus subgenera and species groups suggested formally by Alpert (1994), and to determine evolutionary relationships among subgenera. I also hope to elucidate the importance of characters for future phylogenetic analysis, with particular focus on characters related to a myrmecophilous habit.

3.3 Methods 3.3.1. Analysis

A total of 450 Cremastocheilus specimens were borrowed from The Ohio State

University Insect Collection, University of California-Riverside Entomology Research

Museum, University of Nebraska State Museum, Los Angeles County Museum of

Natural History, Albert J. Cook Arthropod Research Collection at Michigan State

University, and the Museo de Zoologia, Universidade de Sao Paolo. Four species,

including C. robinsoni Cazier, C. academicus Krikken, C. setosifrons and C. chapini

Cazier were not included in the analysis due to unavailability of specimens. The inclusion

of C. (Macropodina ) depressus in the analysis follows Warner (unpublished thesis)

who recognized it as a unique species, although previous authors have synonymized

it with C. (Macropodina ) planatus . Three related Nearctic Cremastocheilini were used as outgroups, namely Genuchinus ineptus , Cyclidius acherontius and Cycl. elongatus .

Genuchinus is assumed to be a close relative based on overall morphological similarity

(Alpert 1994) and other cremastocheilines are rare in collections. Alpert’s key was used to identify numerous misidentified specimens, particularly species that appear to be part of larger species complexes (see Alpert 1994). A total of 52 external adult morphological characters were used in this analysis (see next section). Inapplicable characters were coded as “-”, while missing, unknown or highly variable characters were coded as “?” (see Table 2 for character coding used). The choice of characters was based in part on previous suggestions by Krikken (1982), who was the first to propose a set of characters only for C. (Trinodia ). Characters related to genitalia and

wing venation were not used because they have previously been established as invariant within the genus (Cazier 1938). Uninformative characters were removed from the analysis. Species that vary in relevant characters were coded as morphotypes of a species to recognize this variability. Male and female characters were not coded separately as sexes are not known to differ in external morphology except for the presence of a tibial tooth in the males (Alpert 1994). Initially, all characters were run equally weighted and non-additive. The final matrix included seven characters coded as additive (see

Appendix A). The Parsimony Ratchet (Nixon 1999a) was implemented in NONA

(Goloboff 1999), and run within Winclada (Nixon 1999b) with 50 iterations, beginning with one starting tree and weighting approximately 21% of characters (11/52). The trees obtained by the Ratchet were used as starting trees in a “max*” (TBR branch swapping) search that produced 24 equally parsimonious trees of 149 steps. Suboptimal trees were searched, but none were found, leaving 24 equally parsimonious trees of 149 steps. A more thorough search using mult*100 and a successive max* search algorithm was performed, but the same 24 equally parsimonious trees were found. A strict consensus of the optimal trees was performed, with 4 collapsed nodes, yielding a tree of 153 steps (CI

= 0.46 and RI = 0.80, Fig. 1). Bremer support was determined using Nona, and was set to a support level of 5. Clade support was estimated using jackknifing where each search consisted of 1000 replications, 5 reiterations of random additions of taxa, and holding a maximum of 10000 trees per replication. TBR (max*) was initiated with one starting tree per replication.

3.3.2. Characters used in analysis

Characters used are outlined below. Consistency indices (CI) and retention indices (RI) are provided for all characters based on the resulting phylogeny. Those characters noted with an asterisk (*) were considered to be additive, and are numbered beginning with character “0.”

0. Frontoclypeal transition (CI 0.50, RI 0.85)

The frontoclypeal transition refers to how the frons and clypeus are oriented. In lateral view, the two parts of the head appear to be continuous in outline in some species; in others there appears to be an abrupt angle at which the two meet.

(0) Discontinuous or abrupt;

(1) Continuous

1. Mentum thickness (CI 1.00, RI 1.00)

The menta on some species are thickened and appear almost as a thick plate covering the

mouthparts ventrally; other menta are thin and may be curved. All beetles within the

Cremastocheilini tribe bear these protective menta, which are suggested to protect the

mouthparts; however, since not all Cremastocheilini are ant associates, it is likely to serve

another purpose related to predation, as all taxa within the tribe are thus far known to

feed on various other insects not restricted to ants

(0) Mentum thickened throughout;

(1) Mentum thin

2. *Mentum depth (CI 0.50, RI 0.83)

The mentum shape can vary significantly among taxa. Some are entirely flattened, while others are slightly concave, and others are bowl-shaped.

(0) Flattened;

(1) Moderately concave, like a shallow cup;

(2) Deeply concave/bowl-shaped

3. Base of mentum (CI 0.66, RI 0.90)

The bases of the mentum in Cremastocheilini differ significantly; in the most derived species of Cremastocheilus a notch of various sizes appears, which fits neatly over the

prosternal process.

(0) Angulate, with angles squared;

(1) Rounded;

(2) Notched or emarginate

4. Anterodorsal aspect of mesepimeron (CI 0.33, RI 0.73)

(0) Regularly convex, gradually rounded laterally;

(1) Conical;

(2) Nearly flat, squarely rounded laterally

5. Dorsal face of mesepimeron (CI 1.00, RI 1.00)

(0) Simple, convex;

Figure 2. Mentum of Cremastocheillus species 58

(1) Flattened

6. Mesepimeron medially (CI 1.00, RI 1.00)

(0) Simple;

(1) Tuberculose, where meeting posterior angle

7. Body texture (CI 0.50, RI 0.66)

(0) Rugose;

(1) Polished/smooth

8. Tomentum along base of mesepimeron (CI 0.20, RI 0.20)

(0) Absent;

(1) Present

9. Mesepimeron tomentum at posterior pronotal angle (CI 0.50, RI 0.80)

This character is coded only if the tomentum along the base of the mesepimeron above is

also present. The tomentum present in character 8 is a simple thin patch of fine hairs;

however, a more pronounced tomentum where the posterior angle of the pronotum meets

the mesepimeron is also present.

(0) Absent;

(1) Present

10. Metepimeron (CI 0.33, RI 0.75)

(0) Glabrous, without tomentum;

(1) Tomentose

11. Apical edge of prosternal apophysis (CI 0.25, RI 0.62)

The prosternal apophysis refers to the prosternal process that arises between the two front

coxae.

(0) Bent forward;

(1) Turned downward

12. Proepisternum medially (CI 1.00, RI 1.00)

(0) Simple, flat;

(1) Extending as flaps over bases of procoxae

13. Abdominal tomentum (CI 0.60, RI 0.60)

Patches of tomentum are present in various forms on the abdominal ventrites.

(0) Absent;

(1) Only laterally on segments;

(2) Slightly extending across ventrites;

(3) Completely extending across ventrites

14. Pygidium (CI 1.00, RI 1.00)

(0) Without median longitudinal carina;

(1) With median longitudinal carina

15. Elytral vestiture/setae (CI 1.00, RI 1.00)

(0) Absent (but with tomentum, which are not the same as regular setae);

(1) Entirely absent;

(2) Present

16. Type of setae (CI 0.50, RI 0.50)

The setae are typically the same on the entire body surface. It is difficult to code setal

characters because they often break off or are absent in older, greasy specimens. Thus,

simple or blade-like setae are coded the same, as they appear as simple hairs. Tufted or

brush-like setae appear similar as they are split at the base, regardless of length of setae

present.

(0) Simple, or blade-like;

(1) Tufted or brush-like

17. Tomentum on elytral disc (CI 0.14, RI 0.60)

(0) Present past middle of elytra;

(1) Absent

18. Tomentum at base of elytra (CI 0.50, RI 0.80)

(0) Absent;

(1) Present where meeting posterior pronotal angle

19. Punctures on elytra (uninformative)

(0) Absent;

(1) Present

20. Elytral disc punctures (CI 0.14, RI 0.40)

(0) Mostly closed behind;

(1) Mostly open behind

21. *Spacing of elytral punctures (CI 0.25, RI 0.70)

(0) Sparse;

(1) Separated by one puncture width;

(2) Crowded, separated by less than one puncture width

22. *Elytral puncture shape (CI 0.28, RI 0.77)

(0) Rounded;

(1) Narrowed, almost linear in shape;

(2) Irregular and rugose

23. *Confluence of elytral disc punctures (CI 0.66, RI 0.91)

Confluence suggests a “running together” of the punctures, often as linear or irregular shaped punctures.

(0) Absent;

(1) Somewhat;

(2) Entirely, with all punctures running together

24. Frontolateral carina (CI 1.00 RI 1.00)

In species within the genus Macropodina a frontolateral carina is present, which runs

from behind the eye to the base of the head, and meeting with the anterior pronotal angle.

(0) Absent;

(1) Present

25. *Length of ocular canthus (CI 0.50, RI 0.80)

(0) Extending less than halfway length of eye;

(1) Extending about halfway down length of eye;

(2) Extending almost entirely down length of eye, nearly dividing eye

26. *Lateral edge of ocular canthus (CI 1.00, RI 1.00)

(0) Not protruding;

(1) Slightly protruding;

(2) Strongly protruding

27. Shape of vertex (CI 1.00, RI 1.00)

The vertex refers to the most dorsal portion of the head.

(0) Concave, with median ridge;

(1) Simple, convex;

(2) Flattened

28. Frontoclypeal tomentum (CI 0.40, RI 0.75)

(0) Absent;

(1) As dense patches separated by a medial ridge;

(2) As a continuous patchy strip

29. Ridge above antennal insertion (CI 1.00, RI 1.00)

(0) Simple;

(1) Tuberculate

30. Anterior edge of clypeus (CI 1.00, RI 1.00)

(0) Modified as horns;

(1) Simple, slightly reflexed

31. Sides of clypeus (CI 0.33, RI 0.88)

(0) Rounded;

(1) Angulate

32. Head behind eyes (CI 1.00, RI 1.00)

(0) Normally constricted;

(1) Strongly constricted, appearing neck-like

33. Pronotal angles (CI 1.00, RI 1.00)

(0) Not produced;

(1) Produced as projections

34. Pronotal division (CI 1.00, RI 1.00)

A slight longitudinal division appears in various forms in Cremastocheilus . The species

C. wheeleri has a slight division between the two sets of pronotal angles and the medial disc of the pronotum, which may be due to the enlarged muscle mass within the pronotum; in species in the subgenus Trinodia there appears a strong division that divides

the pronotum into three parts (and this gives Trinodia its name).

(0) Absent;

(1) Slight;

(2) Strong, tripartite

35. Pronotal tomentum (CI 0.50, CI 0.66)

(0) Present;

(1) Absent

36. Proepisternal notch (CI 0.60, RI 0.92, Fig. 2)

The proepisternum is visible in Cremastocheilini, but especially in Cremastocheilus . In

the various outgroups the proepisternum is simple and bears no notch; however, it may

appear slightly notched in lateral view in some species of Cremastocheilus , and is modified in other more derived species by curving upward from the ventral portion to the dorsal aspect of the pronotum.

(0) Absent;

(1) Slight;

(2) Deeply notched;

(3) Extremely deeply notched (with ventral portion curved dorsally)

37. Emargination posterior to anterior angle in dorsal view (CI 1.00, RI 1.00)

(0) Absent;

(1) Present

38. Anterior angle (CI 0.30, RI 0.30)

(0) With only primary trichome present;

(1) With primary and secondary trichome present

39. Posterior pronotal projections positioned (CI 1.00, RI 1.00)

(0) Laterally (Fig. 4A, B, C, F);

(1) Medially (Fig. D, E)

Figure 3. Oblique view of pronotum of Cremastocheilus ; C. (Trinodia ) hirsutus , A; C. (Cremastocheilus ) mexicanus , B; C. (Cremastocheilus ) schaumi , C.

Figure 4. Pronotal diversity in Cremastocheilus species; C. (Myrmecotonus) angularis, A; C. (Cremastocheilus) castanae, B; C. (Macropodina) depressus, C; C. (Cremastocheilus) harrisii, D; C. (Trinodia) hirsutus, E; C. (Anatrinodia) wheeleri

40. Pronotum width (CI 0.33, RI 0.82)

(0) Widest at middle;

(1) Widest anterior to middle;

(2) Widest posterior to middle

41. Posterior pronotal angles (CI 0.33, RI 0.88)

(0) Continuous with lateral margin;

(1) Discontinuous with lateral margin of pronotum

42. Tomentum of anterior pronotal ridge (CI 1.00, RI 1.00)

(0) Absent;

(1) Present

43. *Pronotal disc and posterior pronotal projections (CI 0.50, RI 0.92)

When examining specimens in lateral view, the posterior pronotal angles project strongly in profile and are thus distinctly separated from the pronotal disc by a ridge of various lengths. In the case where a ridge completely separates the pronotum from the pronotal disc the angle may be conspicuously raised in profile.

(0) Continuous, not delineated by ridge;

(1) Delineated partly by ridge;

(2) Completely separated by ridge

44. Inside of anterior pronotal angle (CI 0.25, RI 0.57)

(0) Simple, not notched;

(1) Notched (Fig. 3B, 3D)

45. Tarsal number on all legs (uninf.)

(0) Five;

(1) Four

46. 4th and 5th segment of fore tarsi (CI 1.00, RI 1.00,)

(0) Simple, unmodified;

(1) Modified (enlarged) and bearing trichomes (Fig. 5)

47. Protarsal segments (CI 0.50, RI 0.50)

(0) Compact and continuous;

(1) Normal

48. Position of hind tibial tooth (CI 0.40, RI 0.66)

(0) Posterior to middle of tibia;

(1) At distal end of tibia;

(2) Near or at middle of tibia

49. Posterior tibiae (CI 0.50, RI 0.50)

Figure 5. Modified fore tarsus of C. (Macropodina ) beameri

(0) Simple/unmodified;

(1) Flat

50. Posterior femora (CI 0.20, RI 0.75)

(0) Simple and slender in shape;

(1) Expanded and flattened

51. Bases of all tibiae (CI 0.50, RI 0)

(0) Simple;

(1) Subpedunculate

3.4. Results The strict consensus of 24 equally parsimonious trees (CI = 0.46, RI = 0.80) reveals several monophyletic, resolved clades. The genus Cremastocheilus is a well-defined,

monophyletic group (Jackknife support = 97) comprised of several clades. The subgenera

C. (Macropodina ), C. (Trinodia ), and C. (Cremastocheilus ) are monophyletic.

The hirsutus species group within C. (Trinodia ) is well supported (Bremer support

= 5; Jackknife support = 99). In contrast, C. (Myrmecotonus ) is not a monophyletic

group. The armatus and crinitus species groups within C. (Myrmecotonus ) form a

single monophyletic group, while the schaumii species group appears to be the sister

group of the Cremastocheilus sensu str. + Myrmecotonus clade (including only

armatus and crinitus groups). The recently described C. (Myrmecotonus ) tomentosus

Warner is closely related to the crinitus group, although it has been proposed as

a sister to C. (Myrmecotonus ) robinsoni (Warner 1985) in the C. robinsoni species

group, which was not included in the analysis. Diagnosis of all equally parsimonious

trees indicates that C. wheeleri [in ( C. Anatrinodia )] is the sister of C. (Cremastocheilus ).

Overall, the trees found in this analysis agree with those of Krikken (1982),

whereby C. (Myrmecotonus ) and C. (Cremastocheilus ) are closely related; however C.

(Anatrinodia ) is more closely connected with the C. (Myrmecotonus ) + C.

(Cremastocheilus ) clade than with C. (Trinodia ), which disagrees with original

hypotheses (Casey 1915, Potts 1945) about a close relationship between C. (Trinodia ) and C. (Anatrinodia ).

3.5. Discussion 3.5.1. Subgeneric monophyly

Based on all equally parsimonious trees found, the monophyly of the genus

Cremastocheilus is well supported. Diagnostic characters include the presence of modified anterior and posterior pronotal angles and associated trichomes. Relationships within the genus support some previous hypotheses, but cause the recognition of certain subgenera to be invalid. While subgenera C. (Macropodina ), C. (Trinodia ), and C.

(Cremastocheilus ) are monophyletic, C. ( Myrmecotonus ) is not. Similarly, the monotypic

subgenus C. (Anatrinodia ) is more closely related to C. ( Cremastocheilus ) than to

Trinodia, with which it was previously united by similarity in pronotal shape.

Monophyly of C. (Macropodina ) is supported by enlarged protarsi, frontolateral

carinae bearing glands (Alpert 1994), carinate pygidium, and generally rectangular

body shape. Within C. (Macropodina ) there is poor support for species relationships

below the subgeneric level, and Alpert also only suggested one species group, the C.

(Macropodina ) beameri group, which includes all species within the subgenus. There is

little information regarding the hosts for this subgenus, although the species C.

(Macropodina ) beameri has been collected in and near rodent burrows. Cazier and

Mortenson (1965) suggested that C. beameri uses rodent burrows, particularly those

of Neotoma as sites for mating and overwintering for adults, as well as development of

immature beetles. Ant colonies are often found within or near rodent mounds, and it 73

is possible that these colonies are a source of brood for adults, although beetles have not been found in surrounding ant mounds in the field (Alpert 1994). The species, C.

(Macropodina ) planatus , which is likely a widely distributed species complex, as well as its previously recognized synonym C. (Macropodina ) depressus have been collected with

Camponotus and there is no evidence that it is associated with rodent mounds. Similarly,

C. puncticollis has been collected in Myrmecocystus mexicanus mounds, although this particular host record has been cited as accidental (see Alpert 1994 for host accounts for all species). While these beetles have never been observed to interact with ants, it has been suggested that the long forelegs can be used to wipe ants from the beetles’ bodies while attempting to enter ant nests (Alpert 1994). Similarly, true functions of the frontolateral and protarsal glands are unknown, although they probably function together since the glands are identical in structure (Alpert 1994).

The monophyletic subgenus C. (Trinodia ) is united by several unique synapomorphies that make it one of the most distinctive subgenera in the genus. All species bear a very prominent trilobed pronotum, a character that gave this subgenus its name. The presence of an upcurved proepisternum, which appears dorsally as a separate nodular lobe, is unique in this subgenus. Although a few unrelated species appear to have a slight frontoclypeal ridge, it is highly developed in C. (Trinodia ). It is suspected that many of these characters are related to myrmecophily. Alpert’s (1994) three species groups are all monophyletic. The C. (Trinodia ) hirsutus group is a unique and well supported species group, with all species bearing an emarginated posterior pronotal angle. All species within this species group are found with ants in the genus

Pogonomyrmex . It is likely that the robust and excited posterior angles in this species group are involved in their interactions with these aggressive ant hosts.

Two species in the species group C. (Trinodia ) planipes are united by very broadly flattened hind tibiae and femora. Both C. (Trinodia ) planipes and C. (Trinodia ) mentalis are found with the ant genus Aphaenogaster . The C. (Trinodia ) stathamae group is supported by unique elytral punctures that appear elongate and fused. This is the only monophyletic group that is united by a character related to punctation, as it appears highly homoplastic throughout the genus. Species in this group are collected with various species of the honeypot ants, Myrmecocystus , as well as with Pheidole .

Species in C. (Cremastocheilus ) comprise a monophyletic group and are united by several unique synapomorphies, including strongly delimited posterior angles and nodulose anterior angles. The majority of species in C. (Cremastocheilus ) bear a notched mentum of various sizes, except for C. nitens and C. chapini , although the monophyly of the subgenus is still preserved given the pronotal characters. In contrast, all species groups within C. (Cremastocheilus ) suggested by Alpert (1994) are paraphyletic. His division of species groups relied mainly on characters related to shape of angles on the pronotum, shape of mentum, and elytral punctures; however, many characters related to elytral punctation show high incidences of homoplasy. The C. (Cremastocheilus ) canaliculatus group is often defined by the presence of a secondary trichome situated by

the anterior pronotal angles; however, this character does not seem to be useful in

defining the group.

The subgenus C. (Myrmecotonus ) is not monophyletic, without removal of the C.

(Myrmecotonus ) schaumii group. This species group lacks highly developed pronotal angles as well as a notch in the proepisternum that is present in all other C.

(Myrmecotonus ). The analysis indicates that the C. (Myrmecotonus ) schaumii group is

the sister group to the C. (Cremastocheilus ) + C. (Myrmecotonus ) clade (with removal of

the schaumii species group). Given that the host records indicate a western United States

distribution for all C. (Myrmecotonus ) species, it is possible that specific ant hosts play an

important role in the relationships indicated. The close relationship of C.

(Cremastocheilus ) and C. (Myrmecotonus ) with removal of the C. schaumii group could

be explained by similar ant hosts. With exception of a few other ant host genera,

including Aphaenogaster and other accidental records (see Alpert 1994), all species in C.

(Cremastocheilus ) and the C. (Myrmecotonus ) crinitus , C. (Myrmecotonus ) armatus , and

C. (Myrmecotonus ) robinsoni species groups, are found with Formica ant hosts. Species

in the C. (Myrmecotonus ) schaumii group have only been collected with Messor species

and was accidentally recorded with Pogonomyrmex subnitidus (Alpert 1994).

The relationship of the species C. (Anatrinodia ) wheeleri with other species and subgenera has never been well understood due to its odd mentum and pronotal structures.

Its initial union with Trinodia was based on elements of the pronotum. Unlike the trilobed pronotum, with the lateral lobes holding large muscles in Trinodia , the pronotum in C. wheeleri contains enlarged glandular clusters (Alpert 1994). The

distinctly trilobed pronotum, up-curved proepisternum, and carinate clypeus support the

monophyly of C. (Trinodia ), characteristics that are not found in C. wheeleri . The strict

consensus indicates that C. wheeleri is a basal species of C. (Cremastocheilus ), but some have suggested that it is a highly derived relative of the subgenus (Warner, pers. comm.). The deeply cup-shaped mentum and notched proepisternum places it close to other C. (Cremastocheilus ), but overall body shape does not match character definitions of any other subgenus. I am hereby synonymizing C. (Myrmecotonus ) and C.

(Anatrinodia ) with C. (Cremastocheilus ), which should be cited as such in following

works regarding the genus (see Table 3).

3.5.2. Characters of phylogenetic importance

The role of glands and associated trichomes and tomenta in beetle/ant interactions

are not well understood and thus not described herein (but see Alpert 1994 for extensive histological study). Low consistency index (CI) values indicate a high occurrence of homoplasy, which could be due to myrmecophilous habits. Some behavioral work has shown that even species that are closely related do not interact with ant hosts in the same way. For example, C. (Trinodia ) hirsutus enters nests on its own, without aid from ants, while closely related C. (Trinodia ) saucius is pulled into mounds by ants (Alpert

1994). This could suggest that characters related to certain myrmecophilous behaviors are homoplastic. It might also suggest a divergence in behaviors that could lead to speciation. The behaviors of beetles may also be directly associated with ants’ bionomics.

For example, beetles may leave or enter ant nests depending on season, or on the ant hosts themselves. Depending on the time of year, or whether ants are in the process of migrations, seeking new locations for ant nests, or even when reproductive leave the nest to find mates, beetles may have evolved to respond to those specific behaviors in ants.

Thus far, these specifics have not been examined, but suggest an interesting area of study.

Understanding the ants themselves may provide great insights into the behavior of the beetles.

Thus far, some behavioral information has been used to discuss interactions between ants and myrmecophiles. Ants are known to “lick” or bite pronotal angles of

Cremastocheilus , which is likely to be rather host-specific with respect to the mandibles of the ants and may drive the evolution of the pronotal projections. Wheeler (1908) suggested that the shape of the posterior pronotal angles is likely shaped by ant mandibles. As such, the only pronotal characters that indicate relatively low CI values are

the shape of the posterior angles (Wheeler 1908) and the appearance of a notch in the

anterior pronotal angle in unrelated species of C. (Trinodia ) and C. (Cremastocheilus ).

Ant hosts of these two groups differ, suggesting separate selective pressures by different ant hosts. Characters related to the patches of setae (tomenta) distributed across the body are also supported by low CI’s. The frontoclypeal tomentum, elytral disk tomentum, and ventral abdominal tomentum appear in various unrelated Cremastocheilus species.

Similarly, there is a strip of tomentum along the base of the mesepimeron, which is found in five species, only two of which are closely related. These tomenta are probably linked to interactions with ants, and may have associated exocrine glands. For example, the frontal tomentum is has been shown to be associated with the frontal glands found in histological sections in C. wheeleri and the hirsutus group of C. (Trinodia ) (Alpert 1994).

The placement of glands, which were coded by using external trichomes or tomenta, appears to be a relatively good character in distinguishing subgenera or even species groups, particularly in the case of trichomes. For example, tarsal glands are found only in C. (Macropodina ) and frontal glands are found in closely related C. wheeleri and species in C. (Cremastocheilus ). Externally, tomenta above the antennal insertions are associated with the frontal glands in C. (Cremastocheilus ). Most species in the genus bear tomenta on the metepimeron and many species have tomentose areas along or on the lateral portion of the abdominal sterna. Alpert (1994) found evidence of glands in

C. (Trinodia ), C. (Myrmecotonus ) armatus and C. (Myrmecotonus ) pulverulentus . Other tomentose areas are not at all associated with internal glands, especially those tomenta on the elytra of many species, which appears to be highly homoplastic. Tomentum at

the base of the mesepimeron in several species is also homoplastic. Similar tomenta are found throughout the Cetoniinae. Alpert (1994) suggested that the elytral punctures were reliable in defining species groups and even identifying species in many cases.

Elytral characters used in this analysis did not prove to be useful in uniting species groups, and three of the four elytral characters used had very low CI values. However, because most of Alpert’s species groups appear to be well-defined monophyletic clades, it is evident that many other useful characters still unite those groups.

Tomenta and other myrmecophilous structures may be under strong selective pressures by ants, it is also likely that distinct monophyletic groups revealed in this analysis are associated with specific ant host genera, a pattern that has been shown in sceptobiine staphylinids associated with ants (Danoff -burg 1994). Alpert’s (1994) hirsutus group in C. (Trinodia ) is almost exclusively collected with Pogonomyrmex ant hosts; the C. (Trinodia ) planipes group is associated only with Aphaenogaster spp . In addition, C. (Cremastocheilus ) species, as well as C. wheeleri and the majority of species in C. (Myrmecotonus ), are most often collected in Formica mounds. The related C.

(Myrmecotonus) is also most often found with this particular ant species, and based on phylogeny, there is an indication that closely related Cremastocheilus species are more likely to be found with ant hosts of the same genus, which supports Alpert’s (1994) hypothesis that different Cremastocheilus species have evolved in response to ants, rather than being on an evolutionary “track” towards being fully integrated.

3.5.3. The evolution of myrmecophily in Cremastocheilus

True interactions between beetles and their respective ant hosts should elucidate

evolutionary patterns regarding strategies used by different Cremastocheilus species.

Based on the characters used in this study, it is evident that many characters related to

myrmecophily are informative at the subgeneric level, but others are not. Trichomes,

which are assumed to play an integral part in beetle/ant host interactions, show low

instances of homoplasy, while some tomenta and the elytral punctures indicate multiple

origins and are less phylogenetically informative. Based on this study, future work should

include characters related to myrmecophilous habits, and addition of molecular data

would be very useful.

With regards to the evolution of myrmecophilous interactions within the genus,

information on myrmecophilous interactions is lacking for the majority of species in the

genus; therefore, making predictions about the evolution of myrmecophily within the

group is difficult. It is generally assumed that all species within Cremastocheilus are

myrmecophilous, even without data supporting the habits and behaviors of the majority

of species. Wheeler (1910) suggested that Cremastocheilus has undergone a reversal in stages of myrmecophily, such that the genus was reverting from a true myrmecophile to one that may just be tolerated by ants. If using Wasmann’s terminology with this hypothesis, then Cremastocheilus has moved from “symphile” to “synoekete.” Based on

the knowledge that even closely related species use very different methods by which to

enter ant nests, and may be treated either indifferently or with hostility by respective ant

hosts, Cremastocheilus can currently be considered only to be an obligate myrmecophile at this stage. That is, the genus relies on ant nests for survival.

The presence of trichomes is indicative of very close interactions with ants, and supports the existing behavioral data. Until additional information can be gathered, or unless more species of Cremastocheilus can be studied in terms of myrmecophilous interactions with specific ant hosts, we are left relying primarily on morphology to predict how these beetles are associated with ants. Morphology appears to be useful in predicting general behavioral patterns, but may not necessarily capture intricate interactions that may be more species-specific.

Table 2. Taxonomic history of the subgenera within Cremastocheilus (*denotes inclusion of C. wheeleri )

Horn 1879 Mann 1914 Casey 1915 Cazier 1938 Potts 1945 Cremastocheilus Cremastocheilus Cremastocheilus Cremastocheilus Cremastocheilus Myrmecotonus Macropodina Macropodina Macropodina

Trinodia Trinodia Trinodia Anatrinodia* Anatrinodia* Anatrinodia*

Howden 1971 Krikken 1982 Alpert 1994 Mynhardt 2010 Cremastocheilus* Cremastocheilus Cremastocheilus Cremastocheilus*

Macropodina Macropodina Macropodina Macropodina

84 Trinodia Trinodia Trinodia* Trinodia Anatrinodia* Myrmecotonus

Chapter 4: Phylogenetic analysis and evolution of myrmecophily in the spider beetles

4.1. Introduction 4.1.1. Spider beetle taxonomy

The spider beetles are a morphologically diverse group of insects that has a taxonomically complex history. The most easily recognizable spider beetles are small and globular in shape and bear elongate legs and declined heads that resemble the two- segmented façade of true spiders. Other species are considered to be of the “bostrichoid,” or wood-boring or wood-feeding types with more elongate parallel-sided body shapes that are typical of many related groups of beetles within the Bostrichoidea.

Spider beetles are primarily scavengers that feed on numerous sources of organic detritus; they can thus be collected in or on a variety of substrates. Some spider beetles feed as scavengers on dead or decaying wood (Howe 1959), but thus far only the species

Ptinus lichenum Marsham is known to be a true wood borer. This particular species may indicate a biological transition between other wood-boring Bostrichoidea and more generalistic spider beetles (Bellés 1980), a finding that complicates a hypothesis made by

Crowson (1955), who suggested that spider beetles diverged from the closely related

Anobiidae by the loss of a wood-boring habit.

Other spider beetle species in the genera Gibbium and Mezium (Bellés 1985, Irish

1997) are considered to be important economic pests feeding on grains, decaying wood, and other stored food products. Certain species in the genera Niptus (Shaw 1948, 1973),

Ptinus (Verdcourt 1988, 1993), and Sphaericus (Verdcourt 2002) are also sometimes collected in herbarium specimens, and recently a pair of specimens in the genus

Trigonogenius was collected in preserved plant specimens in the Ohio State University

Herbarium (personal observation). The species Pitnus antillanus Bellés has also been documented to graze on leaves during the larval stage, representing a unique biological derivation in the family (Philips et al. 1998). Since they are scavengers, many spider beetle species can be collected or reared (Keith Philips, pers. comm.) in the dung of mammals, particularly those taxa distributed through southern Africa (Howe 1959).

Others can be collected in the nests of other animals such as birds (Cutler & Hosie 1966) and rodents (Hicks 1959), and several spider beetles are associated with social insects, including bees (Linsley & McSwain 1942), and ants (reviewed by Lawrence & Reichardt

1966, 1969). The ant-associated spider beetles are especially unique in morphology, and all are considered to be obligate inquilines of ant nests where they are tolerated and usually groom their ant hosts. Morphological adaptations in these beetles are similar to most other myrmecophilous Coleoptera, and include modified antennae and the presence of patches of setae and glands known as trichomes. Currently, 66 unique genera, and

close to 700 species are described, most of which occur in drier regions (Howe 1959) worldwide.

Spider beetle taxonomy has undergone various significant changes, and the status of the group has been altered several times by numerous authors. It should first be noted that although the spider beetles are commonly referred to as such, they have been recognized as a unique family, subfamily, and tribe at various instances. Bellés (1994) and Downie & Arnett (1996) recognized the spider beetles as the Ptinidae, and as a unique family that is distinct from the Anobiidae. Others have considered the spider beetles to be a subfamily, Ptininae, within the Anobiidae (Crowson, 1981; Lawrence &

Newton 1995). Most recently the spider beetles have been elevated once more to familial status as the Ptinidae (Bouchard et al . 2011), based on the fact that the name Ptinidae, which was initially described as a family in 1802 by Latreille, has priority over the

Anobiidae, the name of which was recognized in 1821. Therefore, the Ptinidae currently consists of all taxa that were previously considered anobiids. Throughout this chapter the spider beetles will be referred to either as Ptininae (within the Ptinidae), or casually as spider beetles.

The phylogenetic relationships among the spider beetles and several closely related families have been studied extensively. Thus far the spider beetles are considered a monophyletic group based on both molecular (Hunt et al. 2007, Bell & Philips 2012) and morphological studies (Philips 2000); however, all of these studies attempted to reconstruct relationships among three major families within the superfamily

Bostrichoidea, including theAnobiidae, Bostrichidae and Ptinidae (spider beetles)and thus

far none of these study included enough taxa to adequately test relationships among taxa

within the spider beetles. Only the most recent molecular study aimed at elucidating

higher-level relationships among various Bostrichoidea has sampled a significant number

of spider beetle taxa to test whether the group is truly monophyletic (Bell & Philips

2012). In light of Bell & Philips’ study, monophyly of the Ptininae is presumed herein.

4.1.2. Subfamilial taxonomy of the spider beetles

Bellés (1985) examined taxonomic distinctions among taxa within the spider beetles,

respective subfamilies (if spider beetles are considered a family) and suprageneric groups

created to combine various genera that appear morphologically similar.

Bellés initially suggested that the spider beetles are comprised of two unique

subfamilies, including the “derived” Gibiinae and the “basal”, but heterogeneous, group

Ptininae. The Gibbiinae includes several of the typical globular, wingless genera of spider

beetles that most resemble spiders, including Gibbium , Sulcatogibbium, Mezium ,

Stethomezium , Meziomorphum , Costatomezium , and Damarus . The first two genera are

easily recognized by the presence of distinct, elongate hind trochanters as well as

hairless, “triconoconic” pronotum that is conical and triangular in cross section and were

later grouped into the Gibbiini. Other gibbines ( Mezium , Stethomezium , etc.) were placed

into the Meziini.

The rest of the spider beetles placed into the Ptininae, which includes all other described genera within the family (Bellés 1985). Bellés divided the Ptininae into two tribes, the Sphaericini and Ptinini.The sphaericines and ptinines are typically

distinguished from one another based on relatively simple pronotal structure in the

Sphaericini. Bellés noted that the Ptinini is largely a heterogeneous group of spider

beetles which differ greatly in morphology. Since this work is not focused on higher-level

taxonomy, I am accepting the suggestions made by Bellés (1985) and Bouchard et al.

(2011), and hereafter I am recognizing at least four tribes, including: the Gibbiini

Jacquelin du Val 1860, Meziini Bellés 1985, Ptinini Latreille 1802, and Sphaericini

Portevin 1931.

In addition to these groups, the myrmecophiles are currently informally

recognized as being part of the Bellés’ Ptininae, or based on recent re-classification, the

tribe Ptinini, since they bear characters close to species of Ptinus or related taxa. Whether myrmecophiles should be considered as unique subfamilies or tribes within the spider beetles depends on a well-supported phylogeny based on a variety of evidence. Currently, however, the various myrmecophilous taxa are often hypothesized to be independently derived (Lawrence & Reichardt 1966, 1969), but close to the more basal spider beetles, specifically those in the genus Ptinus . Based on these hypotheses, the myrmecophiles are considered to be part of the Ptinini, which is supported in part for New World taxa

(Philips 2000), but is largely unknown for Old World taxa

4.1.3. Bellés’ suprageneric groups

In addition to Bellés’ subfamilial groups, he suggested various generic groups to encompass the morphological diversity found in the spider beetles. At the time when

Bellés (1985) proposed his generic groups various taxa had not yet been described, and

successive described taxa are informally added to these groups. I have created a table (see

Appendix B) that outlines all currently recognized spider beetle genera, along with their suprageneric placement, geographic information, and whether the taxon is included in this study. In summary, Bellés’ existing groups include the basal Xylodes and

Maheoptinus groups, Gynopterus or Dignomus group, in addition to Trigonogenius ,

Sphaericus , Ptinus , Casapus , Niptus , and Gibbium groups. The placement of these groups within existing tribes, as well as respective monophyly will be examined. In addition to these taxa are eight additional genera that are associated with ants.

The eight myrmecophilous genera have never been placed within existing generic groups within the Ptininae, due primarily to presumed autapomorphic charactersthat are predicted to be associated with myrmecophilous interactions. Of myrmecophilous spider beetles, the majority of genera have previously been recognized as belonging to unique families, or genera have been lumped in with other myrmecophilous beetles that now belong to different families within the Coleoptera.

4.1.4. Myrmecophilous spider beetles

Three New World myrmecophilous genera are recognized, including Coleoaethes

Philips 1998 from Panama, Gnostus Westwood 1855 from Brazil to Florida, and

Fabrasia Martinez & Viana 1965 from Brazil , Colombia, and Cuba (see Philips 1997).

The genera Gnostus and Fabrasia , both of which have been reviewed and revised by

Lawrence & Reichardt (1966) have both been proposed as individual subfamilies,

Gnostinae and Fabrasiinae, within the spider beetles, and Gnostus has even been

recognized as a unique family, the Gnostidae (Gemminger & Harold 1868). Successive

authors have placed Gnostus near the Paussinae (Carabidae), as well as the Pselaphinae

(Staphylinidae), Scydmaenidae, and Ectrephidae, which at the time included several

myrmecophilous ptinines from Australia. Forbes (1926) eventually placed Gnostus within

the spider beetles based on similarities in the venation and folding mechanisms of the

hind wings. Fabrasia has been placed within the spider beetles; and,based on the unique

position of trichomes on the hind femur as well as a generally robust body shape it is

easily distinguishable from Gnostus . Lawrence & Reichardt (1966) suggested that either

genus may be recognized as individual subfamilies within the spider beetles, or as tribes,

depending on further studies; however, elevating individual genera to tribal or even

subfamilial status is questionable, unless they form phylogenetically unique lineages.

In the case of all of these myrmecophilous taxa, little can be said about their

relationships to other spider beetles. Based on Philips (2000) study, all three New World

myrmecophilous genera acquired ant-associated behavior independently (see FIG X –

include). Notably, they all appear basal in spider beetle phylogeny based on Philips’

analysis. This suggests that myrmecophilous taxa, at least New World genera, maintain

plesiomorphic characteristics and may have evolved as unique lineages early in spider

beetle evolutionary history. Including Old World taxa provides a more complete picture

of the evolution of myrmecophily.

Placement of Old World myrmecophiles has also proven challenging. Currently,

43 species in five genera are recognized, and these have been historically placed within the subfamily Ectrephinae. The genera currently included, but which have undergone

major taxonomic changes, include the South African genus Diplocotidus Peringuey 1899, and the Australian endemics Diplocotes Westwood 1869, Polyplocotes Westwood 1869,

Enasiba Olliff 1886, and Ectrephes Pascoe 1866. Historically, the genus Gnostus was

united with Ectrephes in the family Gnostidae (Gemminger & Harold 1869); however,

Wasmann (1894) suggested using the family name Ectrephidae, which included at that

time Ectrephes , Diplocotes , Gnostus, and Polyplocotes . Several authors noted genital or

hind wing similarities between various myrmrecophiles and the genus Ptinus (Sharp &

Muir 1912),which led to the eventual placement of the various “ectrephine”

myrmecophiles within the Ptininae by Wasmann & Mjoberg (1916).

Since the ectrephine (Australian) spider beetles have been placed within the

Ptininae, authors have proposed various schemes to recognize them as separate taxa. The

genera Ectrephes , Diplocotes , Polyplocotes , Enasiba and Diphobia , the latter of which is

now synonymous with Diplocotes , were placed within the Ectrephinae. The Ectrephinae

were later subdivided into the Polyplocotinae, which included the majority of

myrmecophiles; Paussoptininae, which included species with flattened “paussine-like”

antennae that resemble those of the carabid myrmecophile subfamily Paussinae; and, the

Ectrephinae, which included Ectrephes . The South African genus Diplocotidus was

placed within the Ptininae due to the lack of antennal modifications typical of other

myrmecophiles. Other names have been proposed for the various Australian

myrmecophiles. As many as 14 genera have been recognized, most of which were

designated based on antennal differences among species, and included names such as

Hexaplocotes for taxa with six-segmented antennae. Lawrence & Reichardt (1969)

reviewed and revised this group and proposed the five generic names that were mentioned above. It is important to note that authors have used antennal characters to separate genera, particularly the myrmecophilous taxa. The use of antennal characters appears to be one of the cruxes in spider beetle taxonomy, and has led to the description of various generic level taxa that have since been synonymized. I am therefore following the taxonomic proposals made by Lawrence & Reichardt (1969), as well as heeding their proposal that subfamilies or tribes are not valid until generic classification of the entire family is established. Finally, another genus, Myrmecoptinus Wasmann 1916 has been cited as being a myrmecophile; however, based on various suggestions, this genus is very similar to, and was synonymized with, the Southeast Asian spider beetle genus

Sundaptinus (Bellés 1991); Borowski (2007) later revalidated the genus because

Myrmecoptinus has priority over Sundaptinus . Based on the lack of any trichomes or other presumed myrmecophilous characteristicss it is likely not a myrmecophile.

Even with the often confusing taxonomy and various nomenclatural changes among the myrmecophiles, Lawrence & Reichardt (1966) scenarios for the evolution of myrmecophily in the spider beetles, proposingat least five unique origins, and therefore unique groups, of myrmecophilous ptinines. Since this study excludes Myrmecoptinus from the myrmecophiles, their scenario predicts four independent origins of evolution for for Gnostus , Fabrasia , Diplocotidus , and the Australian ectrephines. In addition to these taxa, the Panamian genus Coleoaethes may represent an additional origin of myrmecophily within the group. Thus far, Coleoaethes is supported as a basal ptinine

(Philips 2000). In another molecular phylogeny, myrmecophily also evolves

independently in Gnostus and Diplocotes (Bell & Philips 2012), which is largely expected given the probable geographic origins of these taxa. However, in both Philips

(2000) and Bell & Philips’ studies, myrmecophilous taxa are consistently paired in a sister relationship with Ptinus , which was predicted by Lawrence & Reichardt (1966).

Given the major taxonomic discussions above, this study has two primary objectives. First, I aim to test the monophyly of Bellés’ (1982, 1985) proposed suprageneric groups by including specimens from New and Old World regions. Second, I test Lawrence & Reichardt’s (1966) hypothesis, and examine the origins and potential taxonomic placement of eight myrmecophilous genera.

4.2. Materials and Methods 4.2.1. Taxon sampling

Representatives of 70 spider beetle species in 50 genera (including species representing eight probable new/undescribed genera) of adult spider beetles (Ptininae) were selected and examined In addition, four outgroup taxa belonging to established closely-related families within the superfamily Bostrichoidea were selected for cladistic analysis, including a dermestid in the genus Dermestes Linnaeus 1758 , an endecatomid

Endecatomus rugosus Randall 1838, the bostrichid Prostephanus punctatus , and the anobiid Ptilinus ruficornis Say 1823. Larval and pupal characters were excluded from

analysis due to the lack of data for the majority of taxa, especially from the spider beetles.

Taxa from all geographic areas were included, adding to Philips’ (2000) original study

that included 21 New World species in 18 genera, and tripling the total number of spider

beetle taxa included in his morphological analysis. I excluded taxa (LIST) where lack of 94

specimens, or inability to dissect available rare or type specimens, disallowed assessment

of most mouthpart and wing characters, due to potential problems associated with large

numbers of missing data points (Platnick et al. 1991). Existing descriptions are often

insufficient to fill in these gaps.

Specimens used in this study were borrowed primarily from Keith Philips’

personal collection, many of which were originally loaned and gifted or exchanged from

various collections around the world. In addition, I was able to borrow specimens from a

colleague and fellow spider beetle enthusiast, Xavier Bellés. A single type specimen

(Eutaphroptinus natalensis Borowski 2009, from South Africa) was loaned from the

Natural History Museum in London. It was examined but not included in the analysis.

The majority of specimens loaned from Xavier Bellés and from the Natural History

Museum could not be dissected, as they are rare or are types used in original descriptions.

Those taxa that were able to be dissected were first soaked and rehydrated in water on a hot plate for several minutes, or longer for those specimens that were glued to small cards. Rehydrated specimens were placed in lactic acid to macerate tissues to aid in dissection of the many small, compact specimens that are often difficult to disarticulate.

Specimens that were stored in alcohol were transferred directly to lactic acid. Specimens were then disarticulated using micro-pin probes (wooden dowels with minutin-pins inserted at the tips) and forceps, and parts were stored in a small drop of glycerin on slides, for examination. Various dissecting scopes were used, including a Leica MZ 125 and a Wild M-20. In order to capture some of the characters, disarticulated specimens

were photographed using a compound microscope that was set up with Automontage®

software and a Z-stepper to obtain images.

Specimens used in the analysis of this study can be seen in Appendix B, along

with their geographic location, and the current placement of taxa in respective

suprageneric groups, tribes, or subfamilies proposed by Bellés. All taxa will be preserved

as dissected specimens after completion of this work, and kept in the personal collection

of T. Keith Philips at Western Kentucky University.

4.2.2 . Coding and analysis

Data were entered and characters coded in WinDada, which is part of the

WinClada software package (Nixon 2002). Given the relatively small dataset, this software is efficient in running successive analyses, although the analyses may also be run in TNT if necessary; however, based on suggestions by the authors, TNT is typically more effective and efficient with larger datasets of between 300-500 taxa. Characters that could not be examined, because the part under examination was obscured, broken, or entirely missing, were coded as “?” Inapplicable characters were coded as “-,” and in two rare cases, polymorphisms were coded as “*” or “$” in the matrix. Several analyses were run using Nona (Goloboff 1999), and trees examined in WinClada. All 111 coded characters were coded as non-additive; however, several characters were deactivated based on initial tree searches. These latter characters were hypothesized to be homoplasies that united highly divergent myrmecophiles; others were characters that were originally used in Philips (2000) analysis but which became much more difficult to

code into discrete states in this analysis, given the greater number of taxa used. Thus, this study includes a total of 104 analyzed characters. The character named “ventrites connate” was used by Philips (2000) in his phylogenetic analysis as it is often cited by authors (Lawrence 1982, Lawrence & Britton 1991) as being important in distinguishing the spider beetles from anobiine Ptinidae. This character was difficult to examine in dissected specimens, and the relative fusion of ventrites is not always clear (FIG?). In some cases, there is a complete lack of sutures between individual abdominal ventrites, but in others, sutures are present but ventrites may still be considered “connate” or fused, depending on how flexible the ventrites are. In some gibbiine taxa, such as Gibbium and

Mezium , where fusion occurs between the first two of four ventrites in the former and between the second and third ventrites in the latter, the fusion can be variable.

Based on the highly variable morphology of spider beetles, and given that few characters are known to unite the majority of proposed suprageneric groups proposed by

Bellés, characters were not differentially weighted.

Initial searches were run using the Heuristic Search option in Nona. All searches were completed by holding 10000 trees; 100 replications (mult*100), holding 1 tree per replication. The random seed was always kept at 0 (time) to randomize taxon entry order.

All searches were done with multiple TBR (tree bisection and reconnection, mult*) and

TBR (max*). Trees obtained based on the current dataset were consistently variable in terms of topology, and the resulting strict consensus trees has little resolution; nonetheless, the spider beetles were consistently recovered as monophyletic. The parsimony ratchet was then implemented (Nixon 1999), which resulted in shorter trees.

Heuristic searches were repeated, followed by the ratchet, which consistently resulted in

better, shorter trees. In another search, trees obtained by the ratchet were used as initial

search trees in a Heuristic search. Resulting searches failed to find more parsimonious

solutions, leaving only the Ratchet trees. Thus, every tree obtained by Heuristic Search

was less optimal than any tree obtained by Ratchet.

The Ratchet was used in various searches to find the shortest tree topologies by changing individual parameters, such as increasing or decreasing the Random Constraint

Level (RCL), Sequential Ratchet Run (SRR), decreasing and increasing the number of trees held for each iteration, and changing the number of characters sampled, searches consistently resulted in less optimal trees that varied greatly in general topology. Several of the Ratchet searches resulted in 47 equally parsimonious trees (explained in Results). I ran the same search by using the 47 shortest trees as starting trees, but the same 47 were found after at least 4 iterations. These 47 trees were obtained by completing 100 iterations, holding 1 tree per iteration, sampling 20 characters (19.2% of 104), a RCL of

10, and one SRR. The resulting 47 trees, which were obtained by the most successful

Ratchet searches will be used as a basis for the rest of the discussion and results following, and will be presented as a majority rule consensus, which differs very little from the strict consensus.

In order to test for node support, I ran both Bootstrap and Jackknife estimates.

The Bootstrap method samples characters with replacement to test the robustness of nodes, and is reported as the proportion of replicates in which a clade of interest is recovered (Felsenstein 1985). Bootstrap was run with 1000 replicates and 10 iterations

per replicate; no additional branch swapping was used. Bootstrap values higher than 50% are indicated in the consensus tree (Fig. 11) In order to compensate for potential problems with the Bootstrap (Soltis & Soltis 2003), especially concerning its sensitivity towards increased amounts of data or taxa, the Jackknife, which samples characters without replacement, was also used, and additional branch swapping using TBR was used for all replications (1000, with 10 iterations). Bremer support was also calculated to further estimate the strength of node stability. Bremer support is considered a “decay” type of analysis, which allows one to calculate how many steps in less optimal trees are needed to collapse a given node. I selected a suboptimality level of 5 to examine nodes that are still supported when suboptimal trees of 5 steps or greater are considered.

4.2.3. Characters coded

Only characters used in analysis, and with calculated consistency (CI) and retention index

(RI) values are numbered. Characters that were deactivated (6) are mentioned at the end of the list; a single uninformative character is included.

Head: Eyes

1. Eye shape (CI 0.08; RI 0.66)

(0) Approximately round;

(1) Semicircular

2. Eye setae (CI 0.05; RI 0.36)

(0) Absent between ommatidia;

(1) Present between ommatidia

Many spider beetle taxa bear short setae between the individual ommatidia that comprise the compound eye. The use of setae is generally not advised since setae can break off; therefore only the presence or absence of setae (and not length) is noted here.

Antennae

3. Number of antennal segments (CI 0.50, RI 0.40)

(0) 11 segments;

(1) 10 segments;

(2) 9 segments;

(3) 8 segments;

(4) Fewer than eight

The antennae are reduced in most myrmecophilous genera, but several non- myrmecophilous genera also have slight reductions in antennae from the typical 11 antennomeres to 9 (ex. Pitnus ; Electrognostus intermedius , fossil species).

4. Apical antennomere width (CI 0.25, RI 0.14)

(0) Apical antennomere equal in width to penultimate;

(1) Apical antennomere distinctly wider than penultimate;

(2) Apical antennomere narrower than penultimate

100

5. Antennal club (CI 1.00, RI 1.00)

(0) Antennal club present;

(1) Antennal club absent

No species of spider beetle, nor the anobiine outgroup Ptilinus bear an antennal club. An antennal club is defined here as an expansion of the apical three antennomeres into what might appear as a rounded ball to the naked eye.

6. Antennal shape (CI 0.33, RI 0.45)

(0) Clubbed;

(1) Filiform;

(2) Serrate (sometimes very slightly);

(3) Moniliform (paddle-like)

No spider beetles ae are known to have clubbed antennae (see Antennal club character

above). Most have some degree of filiform antennae; however, the myrmecophiles and a

few other genera have highly unique antennae that are difficult to classify as filiform (ex.

Ectrephes ), and could also be classified as moniliform or bead-like antennae.

7. Antennal insertion (CI 1.00, RI 1.00)

(0) Antennae inserted near lateral edge of head;

(1) Antennae inserted between eyes

The Anobiinae are generally separated from the spider beetles by having the antennae inserted distally, or, near the lateral edges of the head. In Ptininae the antennae are

101

inserted between the eyes, although variations of this occur in some undescribed genera from South Africa and Peru.

8. Interantennal space (CI 0.12, RI 0.43)

(0) Flat (or very slightly concave);

(1) A narrowly rounded ridge;

(2) A sharp-edged ridge;

(3) Broadly rounded ridge

9. Fronto-clypeal suture (CI 0.25, RI 0.62)

(0) Distinct;

(1) Indistinct or absent

10. Eye and antennal sexual dimorphism (CI 0.33, RI 0.00)

(0) No major differences between the sexes;

(1) Obvious size and shape differences

Labrum

The labrum is the anterior most sclerotized mouthpart found on the spider beetle head.

The labrum base, where it is attached to the head, is typically unmodified; however, the anterior edge varies greatly.

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11. Anterior edge of labrum (CI 0.16, RI 0.41)

(0) Emarginate;

(1) Truncate or nearly so;

(2) Pointed;

(3) Broadly rounded

The anterior edge of the labium can be described as follows: “Emarginate” typically refers to a antero-medial excavation; “truncate” refers to a squared edge as if it has been cut with a straight edge; “pointed” refers to a definite acute projection that appears as a point; and “broadly rounded” appears similar to the “truncate” type, except that the borders are rounded, rather than squared.

12. Labrum carina (CI 1.00, RI 1.00)

(0) Labrum carina absent;

(1) Labrum with a v-shaped carina ventrally

A ventral ridge or carina is present on the ventral aspect of the labrum of some taxa, particularly those associated with ants.

Mentum

The mentum lies beneath the labium on the anterior edge of the spider beetle head. It appears as a semi-triangular plate in the majority of spider beetles, but varies greatly in the Coleoptera.

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13. Width to length ratio (CI 0.11, RI 0.54)

(0) Wider than long (1:0.80 or less)

(1) Longer than wide (1:1.25-1.50);

(2) As wide as long, or nearly so (1:080-1.20)

14. Mentum groove (CI 0.08, RI 0.66)

(0) Groove absent;

(1) Groove present, although maybe only slight

The outgroup taxa generally lack a groove on the dorsal aspect of the mentum. The majority of spider beetles bear a groove; however, the shape and relative depth of each groove or cavity vary.

15. Mentum groove ( if absent in #16, it is coded as “-;” uninformative)

(0) U-shaped;

(1) As a single round dimple or indentation

16. Longitudinal carina (CI 0.25, RI 0.62)

(0) Absent;

(1) Present

17. Anterior edge of mentum (CI 0.30, RI 0.36)

(0) Anterior edge emarginate

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(1) Anterior edge truncate or blunt;

(2) Anterior edge broadly rounded;

(3) Anterior edge narrowly rounded

The anterior edge of the mentum is highly variable, but uses the same definitions as for the labrum. In this case, “emarginate”, refers to the margin of the mentum appearing excavated.

Maxilla

The maxillae and their palps are used to define particular groups of spider beetles.

Palpomeres are commonly used to distinguish between Anobiidae and Ptinidae.

18. Sclerotized portion of first (basal) palpomere (CI 1.00, RI 1.00)

(0) Slightly arched (45 degrees or straight; Fig. 7A, 7C);

(1) Strongly arched (about 90 degrees Fig. 7B)

The first palpomere of the maxillary palp in spider beetles is very obviously curved

inward at an angle of about 90 degrees. In other bostrichoids the first palpomere is very

slightly bent (less or equal to 45°), or more or less straight, similar to some basal taxa

within the spider beetles ( Scaleptinus and a new genus from South Africa).

19. First (basal) palpomere length (CI 0.50, RI 0.75)

(0) First palpomere shorter than second;

(1) First palpomere longer than second

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Figure 7. Maxillae of Ptilinus (A), Hanumanus (B), and Scaleptinus (C)

20. Length of terminal palpomere of maxillary palp (CI 0.66, RI 0.66)

(0) Normal; between 3x and 4x longer than second palpomere;

(1) Very elongate; approximately 6x longer than second palpomere;

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(2) Very short; approximately 2x as long as second palpomere

21. Galeal length (CI 1.00, RI 1.00)

(0) Galea about the same length as lacinia;

(1) Galea shorter than lacinia (less than half the length)

The galea is found on the distal edge of the maxilla (stipes), between the palp and the lacinia. In the majority of spider beetles the galea is much shorter than the lacinia, except for basal taxa ( Scaleptinus , and a new genus from South Africa).

22. Galeal setae length (CI 0.14, RI 0.53)

(0) Setae shorter than the length of galea;

(1) Setae the same length as galea (when measured from base of seta to tip)

(2) Setae distinctly longer than galea

23. Lacinial spines (CI 0.28, RI 0.00)

(0) Lacinia with stout, spines (usually also with setae);

(1) Lacinia without spines;

(2) Lacinia with a single curved spine

The lacinia is situated medially on the maxilla and usually bears a dense brush of setae.

Spines are often present on the lacinia, and usually obscured by brushes of setae. This character, used by Philips (2000) does not denote the difference between “spine-like

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setae” and “spines.” I define spines as thick, socket-less extensions of the exoskeleton, whereas setae have obvious sockets. The setae are coded separately.

Labium

24. Labial spatulate setae (CI 0.50, RI 0.00)

(0) Spatulate setae absent;

(1) Spatulate setae present

Spatulate setae are only present in two related spider beetles ( Gibbium and Mezium ).

“Spatulate” refers to setae that appear broad/rounded or expanded at the apices, rather than pointed.

25. Labial paraglossae (CI 1.00, RI 1.00)

(0) Labium with distinct triangular lobes;

(1) Labium with distinct parallel-sided lobes;

(2) Labium without distinct lobes

The medial portion of the labium often bears lobes, or ligulae. Spider beetles typically lack ligulae of any form, so it is only found in non-ptinine groups. The ligula is a fusion of the glossae and paraglossae that are usually easily distinguishable in the general insect form.

26. Labial lateral lobes (CI 0.08, RI 0.47)

(0) Absent;

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(1) Present

27. Labial setae (CI 0.16, RI 0.33)

(0) Concentrated at the apical margin of the glossa;

(1) Extending posteriorly in two broad rows;

(2) In an isolated triangular patch medially on glossa

28. Labial palp (CI 0.33, RI 0.60)

(0) Apical end tapered to a point (“fusiform”);

(1) Apical end of palpomere emarginated

The terminal palpomere of several genera of spider beetles have the palpomere emarginate, so that it appears excavated medially, instead of pointed (ex. Coleoaethes ,

Prosternoptinus ).

29. First (basal) labial palpomere (CI 0.50, RI 0.50)

(0) First segment shorter than second;

(1) First about the same length or slightly longer than second

Mandibles

The mandibles in spider beetles are relatively uniform. Mandibles are typically used to separate Anobiinae and other Bostrichoidea from the spider beetles by the presence of two apical teeth.

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30. Mandibular teeth (CI 0.22, RI 0.22)

(0) 2 or 3 teeth at apex of mandible;

(1) One tooth at apex and one at middle of mandible;

(2) Single tooth at apex of mandible

31. Mandible outer edge (CI 0.33, RI 0.00)

(0) Mandible without a tooth on outer edge;

(1) Mandible with tooth on outer edge

32. Mandibular pseudomola (CI 1.00, RI 1.00)

(0) Pseudomola present;

(1) Pseudomola absent

The “pseudomola” in Coleoptera appears as a “mola” or molar area on the mandible, which usually functions in the process of chewing food. A pseudomola is not homologous with a true “mola”, as it only appears as a slight expansion of the mandible.

No spider beetles bear a pseudomola; several outgroups including Endecatomus and

Prostephanus do, however.

Thorax: Pronotum

33. Pronotal punctation (CI 0.20, RI 0.61)

(0) Absent;

(1) Numerous large, elongate punctures anteriorly;

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(2) Numerous small, closely spaced punctures;

(3) Two large punctures anteriorly;

(4) Anterior 1/3 or 1/4 with scattered small, widely spaced punctures associated with

setae

All members within the Ptininae typically bear anterior punctures on the pronotum that vary greatly among genera, whereas punctation in the various outgroups used are simple and scattered throughout the pronotum.

34. Pronotal setal tufts (CI 0.09, RI 0.65)

(0) Absent;

(1) Present

A few genera within the Ptininae bear tufts of setae that differ from the setae that are

generally scattered over the entire surface of the pronotum in some taxa. Setal tufts might

exist with other setae on the pronotum, but appear as thickened, hardened brushes of hair.

35. Pronotal constriction (CI 0.33, RI 0.75)

(0) No constriction near posterior border;

(1) With a distinct, strong constriction near posterior border

The spider beetles are usually distinguished from related bostrichoids by a constriction on

or near the posterior border of the pronotum.

36. Pronotal constriction anterior to base (CI 0.11, RI 0.58)

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(0) Absent;

(1) Pronotum narrowed near basal 1/3 to 1/4 of pronotum

(2) Pronotum appearing as if divided near basal 1/3 to 1/4 of pronotum

Several genera within the Maheoptinus group ( Maheoptinus , Xylodes , Hanumanus ,

Sundaptinus ), Prosternoptinus and Bellesus (Ptinus group), and Sulcoptinus (Dignomus

group) bear a distinct transverse break that divides the pronotum into anterior and

posterior portions, often with a distinct gap or excavation indicating the division.

37. Pronotal margin (CI 0.50, RI 0.75)

(0) Pronotum margined laterally;

(1) Pronotal margin absent

Spider beetle pronota are typically margin-less, except for a singular genus ( Neoptinus ), with the dorsal, lateral, and ventral surfaces continuous rather than divided into distinct dorsal and ventral sides. All outgroups bear margins.

38. Prothorax ventral surface (CI 0.20, RI 0.33)

(0) Unmodified;

(1) Modified (concave or reduced) to accept forelegs

39. Prosternal process (CI 0.33, RI 0.66)

(0) Absent;

(1) Present (although often very reduced)

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40. Prosternal process (if present see #42 above, otherwise in applicable; CI 0.11, RI

0.52)

(0) Apex not expanded;

(1) Apex obviously expanded

41. Prosternal process (if present see #42 above, otherwise inapplicable; CI 0.21, RI

0.47)

(0) Extending very slightly ventrally;

(1) Extending ventrally about ½ the length of the coxae;

(2) Extending ventrally about as far as the coxae

42. Procoxal cavities (CI 1.00, RI 1.00)

Procoxal cavities are used to distinguish between major groups of Coleoptera. Among the

Ptinidae, all are known to have open cavities, in which case the coxal cavities are open to the mesosternum, while closely related Bostrichoidea have partially closed to closed cavities.

(0) Partially closed;

(1) Open

Mesothorax: Scutellum

The scutellum is found at the posterior margin of the mesothorax and is the only visible mesothoracic sclerite in most Coleoptera.

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43. Scutellum visibility (CI 0.16, RI 0.83)

(0) Scutellum visible;

(1) Scutellum indistinct or hidden

A character previously used by Philips (2000) notes that some taxa have a visible scutellum, while others have an indistinct or hidden scutellum. The visibility of the scutellum can only be noted when the beetles are intact and not dissected.

44. Scutellum orientation (CI 0.16, RI 0.64)

(0) Scutellum horizontal to plane of scutum;

(1) Scutellum vertical to plane of scutum

The scutellum appears as a small, rounded or triangular expansion that is horizontal to the plane of the scutum, which forms the majority of the mesothorax. This characteristic appears to be common in anobiines, where the body shape is flattened and not compacted as in the spider beetles. The rounded body shape of the groups such as the Gibbiinae has led to modifications in the articulation of various thoracic structures. For example, in some derived genera the scutellum is vertical to the plane of the scutum; while in other cases the entire mesothorax is reduced to such a degree that the scutellum has nearly disappeared; these are coded as inapplicable (“-“). In other cases, the mesothorax is completely fused to the elytra, disallowing articulation; the orientation and other characters below are not visible in this case.

45. Scutellar apex shape (if vertical in #44, CI 0.40, RI 0.00)

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(0) Scutellar apex broadly rounded;

(1) Scutellar apex narrowly rounded or pointed;

(2) Scutellar apex notched/emarginated

The scutellar apex is highly variable within the spider beetles. Philips (2000) separated the taxa in which the scutellar plane is horizontal to the scutum from those that bear a scutellum that is vertical to the plane of the scutum. The apex of the scutellum should not be conditional on its angle. In contrast to Philips, I have combined the characters into one, rather than splitting it into two. “Broadly rounded” denotes a shape that indicates an evenly rounded margin, whereas “narrowly rounded” often approaches an angulate appearance that can appear pointed.

46. Scutellum shape (if horizontal in #44, CI 0.27, RI 0.13)

(0) Truncate; narrowing to base;

(1) Truncate; parallel-sided;

(2) Broadly rounded;

(3) Truncate; (but sometimes broadly emarginate)

(4) Fully emarginate;

(5) Appearing pointed

47. Scutellum/axillary cord attachment (0.18, CI 0.25)

(0) Axillary cord attached perpendicular to long axis of scutellum;

(1) Axillary cord attached obliquely to long axis of scutellum;

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(2) Axillary cord obsolete

48. Scutum and scutellar plane (CI 0.25, RI 0.40)

(0) Scutum and scutellum on the same plane;

(1) Scutum and scutellum on distinctly different planes

The scutum and scutellum can differ in their orientation (see char. “Scutellum orientation”), but the scutellum can also be raised so that it appears on different horizontal plane from the scutum. While most scutella are raised slightly, the variation is notable, except in cases where the scutellum or entire mesoscutum is reduced.

49. Prescutum dorsal anterior margin angle (CI 0.15, RI 0.54)

(0) Prescutum anterior margin with a 90 degree angle;

(1) Prescutum anterior margin with a 140-150 degree angle;

(2) Prescutum anterior margin continuous and nearly straight;

(3) Prescutum anterior margin with a very narrow angle

The prescutum is the most anterior portion of the mesothorax, and is closely articulated with the rest of the thorax and the elytra. The anterior margin of the prescutum differs remarkably in different taxa, so that it can appear almost as a straight line (such as in anobiine ptinids), or can be narrowed so that the two sides of the margin approach closely to form a 90-degree angle (such as in most spider beetles). Philips used three character states here, with an added state that noted an “almost straight, rounded” margin; I am also

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using a fourth state that indicates a very slight, narrow-angled notch appearing in some

taxa.

50. Mesosternal process width (CI 0.05, RI 0.46)

(0) Narrow, 1/6-1/3 width of mesocoxa;

(1) Wide, 1/2-2/3 width of mesocoxa

51. Mesosternal process contacting metasternum (CI 0.33, RI 0.00)

(0) No;

(1) Yes

52. Prosternal process emargination (CI 0.25, RI 0.25)

(0) Absent;

(1) Broadly emarginate

In some cases within the spider beetles, the prosternal process (which extends between the mesocoxae) appears emarginated near the apex/where it meets the mesosternum.

53. Mesepimeron (CI 0.18, RI 0.67)

(0) Visible, distrinctly triangular;

(1) Visilble, narrow;

(2) Invisible

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54. Mesosternal-mesepisternal suture (CI 0.14, RI 0.63)

(0) Present, distinct;

(1) Present, faint;

(2) Absent

Metathorax

55. Metasternum width (CI 0.25, RI 0.66)

(0) Metasternum wider than mesosternum;

(1) Metasternum about equal in width to mesosternum

56. Metasternum sculpture (CI 0.14, RI 0.20)

(0) Smooth and occasionally with small round/oval punctures

(1) With irregularly shaped (oblong) punctures;

(2) Tuberculate

57. Metasternum posterior margin (CI 1.00, RI 1.00)

(0) With a pair of short acute tooth-like projections;

(1) Without tooth-like projections

In several outgroup taxa, tooth-like projections are situated medially on the hind margin of the metasternum; it appears to correspond with very closely-inserted hind coxae.

58. Metasternal ridge (CI 0.11, RI 0.68)

(0) Metasternum without ridge;

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(1) Metasternum with thickened transverse ridge at basal margin

59. Metepisternum (CI 0.17, RI 0.51)

(0) Contacting anterior edge of metacoxae (Fig. 7A);

(1) Contacting lateral edge of metacoxae (Fig. 7C;

(2) Not visible (fused with metasternum; Fig. 7B)

60. Metepimeron sclerotization (CI 0.28, RI 0.64)

(0) Heavily sclerotized;

(1) Weakly sclerotized;

(2) Not visible

Philips (2000) used this character to define the level of sclerotization of the outside

flanges of the metepimeron. In basal taxa, particularly the outgroups, the metepimeron is

extended as a heavily sclerotized flap; in more derived taxa the flange is visible or

completely invisible, and appears more membranous when compared to the flange of

basal taxa.

61. Metathorax hind margin (CI 0.09, RI 0.28)

(0) Continuous;

(1) Medially excavated

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Figure 8. Metasternites of spider beetles; Eutaphrimorphus (A), Neoptinus (B), and Casapus (Casapus ) 120

Legs

62. Procoxae contiguous (CI 0.50, RI 0.50)

(0) Procoxae contiguous;

(1) Procoxae separated

This character was used by Philips (2000), and denotes two distinct states in which the fore coxae are touching (contiguous) or not. Usually, the presence of a prothoracic process divides the two coxae; however, several Anobiidae as well as all myrmecophilous taxa lack this process entirely.

63. Procoxal projection (CI 0.18, RI 0.25)

(0) Procoxae projecting weakly;

(1) Procoxae strongly projecting (and cone shaped)

The procoxae vary in the degree of protrusion when viewed ventrally. In at least one myrmecophilous genus, Coleoaethes , the procoxae are strongly projecting and almost cone-shaped, a state that is shared with all of the outgroups used in this study. Typical spider beetles do not have strongly projecting procoxae, and the potential function of this feature is unknown.

64. Metacoxal separation (CI 0.16, RI 0.72)

(0) Metacoxae separated by a distance

(1) Metacoxae separated by a distance >/= 1/3 the width of the first ventrite

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The hind coxae are separated to various degrees, but fall into two types of separation,

both of which are very obvious in ventral view.

65. Shape of metacoxae (CI 0.12, RI 0.75)

(0) Metacoxae transverse [or approximately rectangular];

(1) Metacoxae ovoid, elliptical or roughly triangular

66. Metacoxal fusion (CI 0.12, RI 0.63)

(0) Metacoxae not fused to metasternum;

(1) Metacoxae fused to metasternum

This character distinguishes two types of metacoxae. It appears that some of the more globular-shaped spider beetles (ex. Pitnus , Sphaericus , Gibbium , Mezium ) bear hind coxae that are fused to the metasternum, in which the metasternum and coxae are indistinguishable.

67. Metacoxal plate (CI 0.66, RI 0.00)

(0) Coxal plates distinct;

(1) Coxal plates only a remnant;

(2) Coxal plates completely absent

The anobiine ptinids and other outgroup taxa can generally be separated from the spider beetles by the presence of a coxal plate, or the remnant thereof. Coxal plates resemble

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reinforced ridges that line the outer margins of the coxae, although the function is not

known.

68. Anterior trochantins (CI 0.20, RI 0.00)

(0) Trochantins hidden;

(1) Trochantins visible

The trochantins of beetles are some of the hardest parts of the leg to see. It appears as a

small sclerite at the base of the leg, and generally articulates with the coxa. Gibbium is the only known genus of spider beetle with a visible trochantin at the base of its fore coxae; otherwise, the Ptininae can be separated from bostrichoids by the absence of visible trochantin.

69. Profemoral shape (CI 0.12, RI 0.36)

(0) Profemur parallel sided or gradually tapering to apex;

(1) Profemur club-shaped distally with widest point beyond middle

70. Protibial length (CI 0.06, RI 0.16)

(0) Protibia distinctly longer than protarsus;

(1) Probtibia about equal or shorter than protarsus

71. Protibia (CI 0.06, RI 0.30)

(0) Protibia with one spur;

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(1) Protibia with no spurs

72. Metatibial spines at apex (CI 0.11, RI 0.57)

(0) Two spines at apex;

(1) One spine at apex;

(2) No spines at apex

73. Protarsi, fourth tarsomere (in dorsal view; CI 0.33, RI 0.50)

(0) Fourth tarsomere unlobed;

(1) Fourth tarsomere lobed

74. Protarsi (in lateral view; CI 0.26, RI 0.31)

(0) No tarsomeres pectinate;

(1) Fourth tarsomere pectinate;

(2) Third and fourth tarsomeres pectinate;

(3) Second through fourth tarsomeres pectinate;

(4) First through fourth tarsomeres pectinate

The protarsi can be pectinate, or comb-like, where individual tarsomeres have a single

extension expanding ventrally.

75. Metatarsal length, first tarsomere (CI 0.14, RI 0.62)

(0) First metatarsomere elongate, about 1.5-2.0x as long as second;

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(1) First metatarsus about equal in length to second;

(2) First tarsomere short, about 0.5x length of second

76. Trochanter attachment (CI 0.33, RI 0.50)

(0) Trochanters attached obliquely;

(1) Trochanters attached squarely

Philips (2000) used this character in his study, and is coded here as the attachment to the coxa of any leg. Oblique attachment means that the sides of the coxa and trochanter do not abut; square attachment refers to the longest side of each portion of the leg being adjacent and aligned.

77. Trochanter length (CI 1.00, RI 1.00)

(0) Short (<1/6 length of femur);

(1) Relatively long (1/4-1/5 length of femur)

(2) Very elongate (>0.5 length of femur)

This character was used by Philips (2000), although the degree of trochanter length was not fully described. The only spider beetle genus with noticeably long trochanters is the genus Gibbium , in which the trochanter is greater than half the length of the femur (hind

leg only). In the anobiine and dermestid outgroup taxa used, the trochanter is relatively

long (between ¼-1/5 as long as the tibia), and “short” denotes trochanters that are less

than 1/6 as long as the femur.

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Elytra

The elytra in the spider beetles are highly variable, with some appearing as globular structures that aid in the spider-like appearance of “typical” spider beetles.

78. Elytral fusion (CI 0.12, RI 0.76)

(0) Elytra not fused;

(1) Elytra fused to various degrees

79. Elytral punctation (CI 0.16, RI 0.16)

(0) Elytra with punctures;

(1) Elytra without punctures

Philips (2000) distinguished between “macropunctures” and “micropunctures.” I am avoiding the use of these terms as size of punctures depends on the position or placement of punctures (ex. Punctures can be smaller near the apex of elytra than at the base). I am using only two states.

80. Puncture arrangement (if punctures present in #82; CI 0.12, RI 0.30)

(0) Punctures scattered all over elytra;

(1) Punctures lined in longitudinal rows

81. Elytral clasp (CI 0.33, RI 0.66)

(0) Elytral clasp absent;

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(1) Elytral clasp present

A small rounded lobe or extension extends outward when viewing the elytra in ventral aspect. The clasp is present in all myrmecophiles, but has not previously been documented. I am calling it a clasp, because it may play a role in keeping the elytra close to the body, which could be useful in defense against ants.

82. Elytral puncture cells (CI 0.05, RI 0.38)

(0) Absent;

(1) Present

In many taxa, particularly those with obvious punctures, a secondary larger cell (not a puncture), in which the puncture is embedded appears, but is only visible in close view, and in dissected specimens.

83. Elytral intermittent punctures (coded as inapplicable for taxa without rows of

punctures; see charater #83; CI 0.11, RI 0.63)

(0) Absent;

(1) Present

In cases where taxa have rows of punctures, a secondary row of smaller punctures are

found as intermittent punctures between existing rows.

84. Secondary puncture (CI 0.10, RI 0.52)

(0) Absent;

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(1) Present

Along puncture rows, a secondary puncture anterior to the existing puncture is apparent in magnified view. This puncture usually bears a small or fine seta.

85. Elytral setae (CI 0.12, RI 0.12)

(0) Setae not obscuring surface of elytra;

(1) Setae completely obscuring surface

Setae can vary significantly in the spider beetles. It is easy to note the differences in setal density so that they appear wool-like (Trigonogenius ) or just as thickened setae appressed

to the surface.

86. Setal length (CI 0.18, RI 0.43)

(0) Short, recumbent setae;

(1) Long, erect and recumbent setae between and along puncture rows;

(2) Setae absent or nearly so;

(3) Scattered, short, recumbent and erect setae

Using the length of setae can be highly problematic. The overlapping or non-discrete

states are difficult to code for so many taxa. It is likely that many more states or the

addition of many more specific characters exist for this character, but thus far the existing

states used by Philips were used. The character state (1) also necessitates the need for

puncture rows as a condition. “Recumbent” refers to setae that are lying nearly flat, and is

opposite from “erect” setae.

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87. Elytral integument surface (CI 0.20, RI 0.00)

(0) Punctate;

(1) Smooth and shiny;

(2) Granulate or tuberculate

88. Integument surface: striae (CI 0.20, RI 0.00)

(0) Elytra lacking striae (straight lines of punctures or tubercles);

(1) Elytra striate with continuous grooves (which may have punctures)

Various taxa in the Gibbium group bear longitudinal striae along the elytra. The striae do not necessitate the presence of punctures; however, the often globose and impunctate

Gibbium group is likely to have undergone a reduction or loss of punctures without the loss of striae.

89. Elytral width (CI 0.25, RI 0.72)

(0) Width elytra less than 2x width of abdominal sterna;

(1) Width more than 2x as wide

This character is difficult to measure precisely since elytra can be very curved; however, ventral view allows one to estimate the elytral width when compared to the abdominal sternites. This character seems only to apply to one generic group ( Gibbium group), and is therefore a synapomorphy uniting all genera in this group.

90. Presence of hind wings (CI 0.33, RI 0.81)

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(0) Hind wings present;

(1) Hind wings absent

91. Jugal lobe (CI 0.25, RI 0.25)

(0) Present;

(1) Absent

92. Wedge cell (CI 0.16, RI 0.28)

(0) Present;

(1) Absent

93. Wing vein AP3+4 (CI 0.50, RI 0.66)

(0) Present;

(1) Absent

94. Cross vein between MP-MP (CI 0.33, RI 0.75)

(0) Present;

(1) Absent

95. RP2 vein (CI 0.50, RI 0.50)

(0) Present;

(1) Absent

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96. R4 vein (i.e. RP and rr connected; CI 1.00, RI 1.00)

(0) Present;

(1) Absent

Abdomen

97. Number of ventrites (CI 1.00, RI 1.00)

(0) Five;

(1) Four;

(2) Three

98. First and second ventrite suture impression (CI 0.14, RI 0.62)

(0) First and second ventrite sutures normal;

(1) First and second ventrite sutures apparently lacking

In a few spider beetle genera (ex. Gnostus , Niptinus , Pitnus ), the first and second abdominal segmental sutures are visibly impressed medially (as used by Philips 2000), so that it appears as if there are no sutures at all. This character is redefined here to describe only the visibility of the sutures themselves, even if sutures are only absent medially on the abdominal sternites.

99. Penultimate ventrite when compared to third last (CI 0.14, RI 0.60)

(0) Approximately equal in length;

(1) Greatly reduced (2/3 to ½ the length of third last);

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(2) Extremely reduced (less than ¼ the length of third last)

In some spider beetle genera there is a great reduction in the length of abdominal segments apically, so that its shape appears almost conical. I am following the coding of

Philips, which compares the lengths of the second-to-last (penultimate) ventrite to the third last.

100. Anterior margin of fourth ventrite (CI 0.50, RI 0.87)

(0) Anterior margin curved;

(1) Anterior margin straight

The Gibbium group of spider beetles bear highly reduced abdomens. The anterior

(lateral) margin of the fourth ventrite appears to be curved posteriorly in all spider beetles and in most Anobiidae, except for the Gibbium group, in which the fourth ventrite margin appears straight laterally.

101. Abdominal ventrite intercoxal process (CI 0.26, RI 0.64)

(0) Intercoxal process absent;

(1) Intercoxal process broadly, gradually rounded;

(2) Intercoxal process narrowly rounded;

(3) Intercoxal process triangular;

(4) Intercoxal process slightly expanded anteriorly

The intercoxal process is part of the basal abdominal segment that is situated between the metacoxae. “Broadly rounded” can be defined as gradually rounded and not very highly

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angulate. “Narrowly rounded” appears more angulate as if cone-shaped. “Triangular” can

be redefined as pointed at the process apex. In the case where an intercoxal process is

“slightly expanded,” its tip appears very similar to the “triangular” shape, but bears an

expansion at the tip.

102. Ventrite borders (CI 0.14, RI 0.33)

(0) Normal;

(1) With crenulate/wavy patterns (punctures) along border (Fig. 9)

103. Ventrites with breaks along sutures (CI 0.33, RI 0.00)

(0) Absent;

(1) Present (Fig. 10)

This character differs from #102 as the ventrites are still delineated by faint sutures; however, small strips of what appears to be sclerotized tissue are present along the basal ventrites’ sutures

104. Spiculum gastrale (CI 0.08, RI 0.50)

(0) With 2 arms;

(1) With 4 arms

105. Aedeagus (CI 1.00, RI 1.00)

(0) Relatively elongate (paramere to basal piece ratio >1.6:1)

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Figure 9. Acanthaptinus triplehorni , showing crenulate patterns (punctures) along abdominal ventrite sutures

Figure 10. Eutaphrimorpus raffrayi , broken sutures along first and second ventrites (arrow)

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(1) Stout (paramere to basal piece ratio <1.5:1)

4.3. Results and Discussion 4.3.1. Analysis

After several iterative runs using both Heuristic and parsimony ratchet searches,

47 equally parsimonious trees of 803 steps, (CI=0.19 and RI=0.53) were found. A strict consensus of the 47 trees (860 steps, CI=0.18, RI=0.52) was relatively well resolved, and depicting three primary clades. Since the ratchet (see Materials and Methods) was found to be the most efficient and continually found the shortest trees, it was run several times, and the same 47 trees were consistently recovered. The strict consensus resulted in 15 collapsed nodes, the majority of which were located in one of the three primary clades that includes taxa related to the genus Ptinus. A majority rule consensus indicates strong support for nearly all clades, but relationships within the typically cited basal clade

(including all Ptinus species) are less well supported. The Jackknife indicated support for very few nodes; however, the spider beetles, or Ptininae s.s ., as a whole are monophyletic and are consistently recovered (99% Jackknife support). The parsimony Bootstrap resulted in similar, although often slightly higher estimates of support for nodes that were recovered by the Jackknife. Bremer support (Bremer, 1994) was strong throughout the tree; however, basal nodes, particularly those in the Ptinus clade, are poorly supported,

while more derived taxa are relatively uniform throughout the topologies examined. High

levels of Bremer support do not necessarily result in high Jackknife support, and nodes

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found in 100% of the equally parsimonious trees were not necessarily supported by

Bremer or Jackknife estimates.

4.3.2. The spider beetles

The spider beetles are a well-supported, monophyletic group and are strongly supported in all examined topologies (including those that resulted from other searches). Jackknife estimates and Bremer support values (5) were high, and the group was recovered in all 47 equally parsimonious trees. Numerous synapomorphies support the spider beetles, including: 1) antennal insertions between the eyes (proximal insertions, compared with wide antennal insertions), 2) antennae without apical club, 3) galeal length shorter than lacinial length, 4) first segment of maxillary palp longer than the second, 4) lack of lateral pronotal margin (except for a slight margin in Neoptinus ), 5) lack of teeth at the posterior margin of the metasternum (which always accompanies closely inserted hind coxae), and

6) typical “ptinine” aedeagus that is defined by relatively long parameres (more than 1.5x as long as the median lobe) compared to the median lobe (Philips 2000). Genitalia were not coded specifically as they are considered more or less uniform in the spider beetles; however, they are often used to distinguish between species in single genera, and may be useful in lower-level phylogenetic studies.

Several characters originally identified by Philips (2000) were also recovered as informative characters of the spider beetles (Ptinidae sensu stricto ), but the addition of certain taxa does not support similar findings in this study. For example, the strongly curved first segment of the maxillary palp was found to be unique among the Ptininae,

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but in the current study, an undescribed genus (Genus nov. 1 SAF, in the tree) from the coastal Knysna region of South Africa, was found to have the first maxillary palp segment nearly as straight as that of the outgroup taxa. This character may therefore not be informative in as far as it does not define the spider beetles, unless this new genus is found to belong to another closely related bostrichoid family such as the Anobiinae. The new genus could be considered an anobiine ptinid based on two teeth at the apex of the mandible, a character that is shared with the anobiine Ptilinus ruficornis that was used as an outgroup taxon in this analysis. Based on other phylogenetically informative characters such as the proximate antennal insertions and simple Ptinus-like antennal segments, the genus is most certainly a spider beetle. It may also serve as a transitional taxon between the anobiine ptinids and the spider beetles.

Within the spider beetles, all equally parsimonious trees recovered three major derived clades, as well as several basal groups that include the majority of myrmecophiles. The first of the three major clades includes taxa typically aligned with the Ptinus genus group, and is found in all equally parsimonious trees recovered in analysis. Bremer support is less than optimal (2) in supporting this clade. The same level of Bremer support values were calculated for the other two derived clades that contain other globular-shaped, typically wingless, and variably setose taxa, including those taxa associated with the Gibbium group, or the Gibiini as well as those genera usually grouped into the Sphaericus group or the tribe Sphaericini (sensu Bellés 1985).

137

138 Figure 11. Strict consensus of the spider beetles, based on 47 equally parsimonious trees (860 steps, CI=0.19, RI=0.52)

4.3.3. Tribal and suprageneric groups

One of the major goals of this study was to determine whether Bellés’ (1982,

1985) proposed suprageneric groups, and several of the long-accepted spider beetle subfamilies or tribes are natural, monophyletic groups. Philips (2000) was able to examine these groups based exclusively on New World taxa. In his study none of Bellés’

(1982) proposed groups, except for the Gibbium group, were monophyletic. Since the current study includes close to three times the number of taxa, better estimates of the monophyly of Bellés’ groups can be made. All equally parsimonious trees and the consensus trees recovered in this analysis indicate that several proposed suprageneric groups, as well as subfamilies/tribes within the spider beetles are monophyletic; however, based on the general topology, some of these suprageneric groups will have to be combined, or should at least be considered as such when discussing the phylogenetic placement of taxa in future work. It is important to note that there are no unique synapomorphies that unite any of the three major clades recovered in this study. There do appear to be some general morphological trends regarding body shape, and the relatively well resolved structure of the strict consensus indicates that there is strong phylogenetic signal, even if not all clades are well supported.

Basal spider beetles in this study include the myrmecophile Coleoaethes ,

Scaleptinus , another myrmecophile Fabrasia , a new undescribed specimen from South

Africa (Genus nov. 1 SAF), and all of the African and Australian myrmecophiles. Since none of these taxa fall into any of the resolved clades, and because the derived clades are assigned to tribes, all basal lineages are assigned new tribal distinctions. The 139

myrmecophilous genus Coleoaethes is placed into Tribe nov. 1. Other basal taxa are also

assigned to informal tribes. Since several taxa were not included in the analysis, it seems

appropriate to refrain from assigning permanent names to these basal taxa, except for the

Old World myrmecophiles that are now recognized as the Ectrephini. Formal tribal

names are assigned to the three derived clades, primarily because they have been used

previously by Bellés (1982, 1985).

One of the major objectives of this study was to determine where

myrmecophilous spider beetles belong in spider beetle phylogeny. Unfortunately, since

most of the ant-associated taxa do not align with any of the existing clades recovered,

very little can be said for their placement within spider beetle evolution, except that these

taxa are basal spider beetles. Except for the genus Gnostus, the myrmecophiles also do

not represent derived Ptinus taxa, as previously hypothesized (see myrmecophily section). These taxa can therefore not be placed within any existing groups within the

Ptininae, but are recognized here as the informal Tribe nov. 1 (for Coleoaethes), Tribe nov. 3 (for Fabrasia), and formally as an expanded Ectrephini, which now also includes the South African genus Diplocotidus .

The genus Scaleptinus , which was recently described from specimens originally considered to be in the genus Ptinus , and which is similar to most Ptinus species, bears the typical parallel-sided body shape, although it also has highly plesiomorphic mouthparts typical of non-ptinine bostrichoids (such as straightened basal maxillary segment). Scaleptinus is thus not considered as part of the Ptinus clade (“Ptinini” in Fig.

11), but is informally assigned to Tribe nov. 2. 140

One of the major derived clades (Ptinini, comb. nov.) recovered includes various

genera that have been placed within their own suprageneric groups (Bellés 1981, 1985) ,

as well as all Ptinus species that were examined herein. This clade appears to be most

problematic regarding resolution; however, strong support exists for the majority of

smaller, more derived sister-groups. The genus Ptinus is not monophyletic, a finding that

has been supported both by Philips (2000), and recently in a combined analysis (Bell &

Philips 2012). This is not surprising, given that the majority of spider beetle genera were

once considered to be in the genus Ptinus and have since been removed and elevated to

generic status. The various proposed subgenera within Ptinus are invalid; but, a more

thorough phylogenetic analysis that includes the several hundred Ptinus species, including all the other unexamined subgenera, may be more useful to test monophyly of the genus as a whole.

Other genera found Ptinini bear similar characters to the majority of Ptinus

species. For example, the genus Niptinus resembles Ptinus (Philips 1998), based on

characters related to the vestiture on the elytra, and the visible, and roughly triangular

shape , as well as the horizontal orientation of the scutellum. The majority of included

taxa that are recovered in the Ptinus clade are generally more elongate in shape (although

in certain Ptinus species the females are more robust and oval in shape) when compared

to the gibbiine or even the Sphaericus clades recovered (described later).

Basal taxa within the Ptinus clade are robust and approach a more globular shape,

while derived taxa like Ptinus or Niptinus bear the parallel-sided shape that is typical of

the bostrichoid, wood-boring type of beetle. These basal Ptinus-like taxa include several 141

genera that have been placed previously within the Niptus (Niptomezium , Eurostoptinus ,

Pseudomezium ) or monogeneric Casapus groups. Based on these results, the Niptus and

Casapus suprageneric groups should be synonymized with the Ptinini. In addition,

several of the most derived taxa within this group, which have previously been

recognized as the Maheoptinus , Xylodes , and Dignomus groups, should also be

synonymized in order to recognize a monophyletic Ptinini. Since the Ptinini appear to be

derived, the previous hypotheses that that Ptinus is a basal ptinine, and the suggestion by

Bellés (1985) that the Xylodes , Maheoptinus and Dignomus groups are basal, are rejected.

In addition, the placement of the myrmecophile, Gnostus supports suggestions that it is closely allied with Ptinus ( Lawrence & Reichardt 1966). I recommend that the clade, including genera included in the Ptinus , Maheoptinus , Xylodes, Dignomus groups, be

recognized as the Ptinini. Other taxa within the clade should also be included within the

Ptinini, the majority of taxa of which bear closely-inserted and transverse (instead of oval

or rounded) metacoxae.

Bellés (1985) originally divided the Gibiini and the Meziini, the former of which

included Gibbium and Sulcatogibbium ; and the latter of which included Meziomorphum ,

Stethomezium , Costatomezium , Lepimedozium and Damarus . If considering Bellés’

Meziini as a natural group, then the Gibbiini recovered in this analysis is paraphyletic.

Based on this analysis, the two tribes are combined into the Gibbiini comb. nov .. The

Gibbiini will also be rendered paraphyletic unless it includes the currently unplaced

genus, Cryptopeniculus , as well as a few new, undescribed genera from Peru, therefore

Cryptopeniculus is placed within the Gibbiini. 142

Cryptopeniculus appears similar to the various Gibbiini due to the smooth, rounded body shape and conspicuous pronotal setae. Philips and Foster (2004) noted that

Cryptopeniculus may be closely aligned to other genera within the Gibbium group by convergence; however, it appears to be a more derived gibbiine related closely to the

Namibian genus Damarus . The Gibbiini are included in a larger clade that circumscribes various other wingless, globular-shaped spider beetles, such as the genera

Trigonogenioptinus from Sri Lanka, Pocapharaptinus from South Africa, and

Acanthaptinus from Madagascar. The two undescribed representatives, one from South

Africa (Genus nov. 3 SAF) and another from Peru (Genus nov. 4 PER) both bear morphological similarities close to the Gibbiini, including rounded body shape and hirsute body form. Placement of these taxa among various African taxa may suggest a

Gondwanan origin for this group. There are no synapomorphies that unite all taxa within this clade, but various characters unite certain genera that are typically considered to be in the Gibbium group. Synapomorphies, none of which are unique to this group, include a longitudinal carina on the mentum (although the carina is lost in the three derived genera), lack of pronotal punctuation (except for fine punctures in the genus Mezium ), the presence of pronotal setal tufts (lost in Gibbium and Sulcatogibbium ), a largely invisible mesepimeron (visible in Lepimedozium ), the loss of a mesosternal/mesepisternal suture, an equally wide meso- and metasternum (metasternum wider in the basal Meziomorphum ,

Cryptopeniculus and “Genus nov. 4 PER”), elytra wider than twice the width of the abdominal sternites (except in “Genus nov. 4 PER”), and a straight anterior margin of the fourth ventrite (except in Cryptopeniculus and “Genus nov. 4 PER”). 143

Based on this analysis, the previously recognized Gibbium group, as well as the more inclusive Gibbiini is monophyletic, and now includes three derived taxa, Damarus ,

Cryptopeniculus and “Genus nov. 4 PER” Based on the current structure of phylogeny, the group may also include other genera that are basal in the clade, such as

Trigonogenioptinus , Pocapharaptinus , Acanthaptinus , the latter of which was informally placed in the Ptinus group by Philips 2005, based on the hypothesis that the typical rounded, hairy morphology similar to various gibbiines is due to convergence. Based on this study, Acanthaptinus can be considered as part of the Gibbiini.

The gibbiine clade is also largely supported when considering biogeographical information. All genera included in this clade are African and Madagascan, although two new genera from Peru (“Genus nov. 3 SAF” and “Genus nov. 4 PER”) should also be included, and may indicate that these taxa shared a Gondwanan ancestor. It is likely that the addition of extra characters or taxa may cause a change in tree topology, especially since support for the basal node of this clade is not very strong (Bremer support estimate

= 2; <50% node recovery in Jackknife/Bootstrap). Based on the topology, I am recommending that all taxa within this clade be united under the Gibbiini.

A third major clade recovered in phylogeny includes various taxa that are also rounded in shape; however, these taxa are generally more hirsute than those in the

Gibbiini clade. It includes all subgenera in the speciose genus Sphaericus . Based on the four subgenera included, Sphaericus does not appear to be monophyletic, particularly because the Australian subgenus S. (Leasphaericus ) appears basal to other subgenera.

Bellés (1998) noted the unique morphological characteristics of this particular subgenus, 144

such as a visible scutellum (a character found only in more basal taxa like Ptinus ), which sets this subgenus apart from others in Sphaericus . Other genera included in this larger clade are Pitnus and Neoptinus (currently included in the Sphaericus group or within the

Sphaericini tribe sensu Bellés 1985), as well as other globular-shaped spider beetles, like

Bellesus (Ptinus group), Niptus , Tipnus , Pseudeurostus (all three in Niptus group),

Lachnoniptus , Trigonogenius , and Africogenius (all three in the Trigonogenius group) and four undescribed taxa (“Genus nov. 5 PER,” “Genus nov. 6 ARG,” Genus nov. 7

AUS,” and “Genus nov. 8 AUS”). Based on representatives included in this clade, Bellés’

Ptinus group is not monophyletic, unless Bellesus is considered to be part of another suprageneric group. In addition, his Niptus group is not monophyletic, as the genus

Niptodes was found within the clade containing all Ptinus and related genera. Since representatives from the Sphaericus , Niptus , and Trigonogenius groups are united together in this clade, and given the fact that the Sphaericus and Niptus groups are paraphyletic, unless they include the Trigonogenius group, I am recommending that all three groups be united under the singular tribe Sphaericini. Philips (2000) found similar relationships among the three suprageneric groups, except that the genera

Trigonogenioptinus (near the Gibbiini in this analysis) and Niptodes (subgenus Niptodes )

(near the Ptinini in this analysis) were also nested within the more globular-shaped spider beetles. The genus Bellesus should also be included in this clade, unless a future analysis places it near the Ptinus group. Since Philips (2000) phylogeny also did not recover a close relationship between Ptinus and Bellesus I recommend placing it in within the

Sphaericini. 145

Since the informal suparageneric groups proposed by Bellés (1982, 1985) appear to be largely superficial (i.e. no good synapomorphies are described to unite the taxa), and almost none of those groups appear to be natural, monophyletic groups Bellés’ superageneric groups are rejected, and instead replaced with tribes that circumscribe monophyletic lineages.

4.3.4. Myrmecophilous spider beetles

Based on this analysis, myrmecophily has originated independently four times in the eight known myrmecophilous genera (Fig. 11), namely 1) in the New World genus

Coleoaethes (Panama; Tribe nov. 1); 2) in the New World genus Fabrasia (Brazil,

Colombia, Cuba; Tribe nov. 3); 3) in the South African genus Diplocotidus and the four

“ectrephine” or Australian myrmecophiles ( Diplocotes , Ectrephes , Enasiba , and

Polyplocotes ; Ectrephini [Fig. 11]), and; 4) in the New World genus Gnostus (Florida,

Bahamas). Only the genus Gnostus can be placed within any existing groups within he spider beetles and is herein recognized as belonging to the Ptinini. In Philips (2000) study, the New World myrmecophiles ( Fabrasia , Coleoaethes , and Gnostus ), each evolved independently, although all were found to be basal in his phylogeny. In this study, Fabrasia and Coleoaethes were basal to the spider beetles, while Gnostus appeared to be more derived within the group containing Ptinus and other elongate beetles. Philips (1998) suggested an independent origin for Coleoaethes based on unique myrmecophilous characters. Unlike the majority of myrmecophilous ptinines,

Coleoaethes bears trichomes on the tips of the elytra, which can be found in other 146

unrelated families of Coleoptera, including Adranes taylori and Claviger testaceus

(Staphylinidae, subfamily Pselaphinae). Fabrasia is also unique since all species of the

genus have trichomes situated on the hind femora, and Gnostus bears trichomes on the

pronotum. Gnostus floridanus is the only species thus far that has been reported to

engage in trophallaxis with ant hosts in the genus Crematogaster , but provided that

Gnostus is not closely related to either Coleoaethes or Fabrasia , the same behaviors

cannot necessarily be assumed for these taxa.

Since the interactions between either Coleoaethes or Fabrasia and respective ant

hosts are unknown, little can be said about the exact role these trichomes play. However,

given that the presence of trichomes typically indicate intimate, obligate associations with

ants (see Chapter 2), these genera are probably associated very closely and have similar

interactions with ant hosts as does Gnostus . Two species of Fabrasia have been collected

with ants in the genus Camponotus (subgenus Myrmothrix ), but the specific ant host of

Coleoaethes is unknown but based on these genera it is likely to have similar interactions

with ants as Gnostus (host ant genus Crematogaster )or Fabrasia , particularly based on

the tree-nesting habits of these ant hosts.

Coleoaethes and Fabrasia are morphologically distinct due to their unique

myrmecophilous adaptations; however, they bear similar plesiomorphic characters that

support their placement in phylogeny. Both are elongate in shape, and have typical

Ptinus -like antennae, with 11 segments. The mouthparts, particularly the labial and

maxillary palps in both taxa are reduced, although details were not coded for either taxon

based on limited specimens and the inability to dissect them. Reduced mouthparts are 147

most likely to be due to a myrmecophilous habit, as all other ant-associated ptinines also

have compact, reduced palps and sclerotized segments of both the maxilla and labium, all

characters that appear to be unique among ptinine myrmecophiles. Another basal

characteristic supporting their phylogenetic placement is the presence of fully developed

hind wings, as well as simple (non-clavate) femora. Based on these results, three

independent origins of Neotropical/New World spider beetles are supported in part by

Lawrence & Reichardt (1969), who recommended two independent origins for Gnostus

and Fabrasia , and in part by Philips (1998), who suggested a third independent origin for

Coleoaethes . Perhaps the most interesting finding is that the majority of myrmecophiles appear to be basal, and bear various plesiomorphic characters. In terms of the evolution of myrmecophilous behavior, ant-associated interactions evolved early, and myrmecophilous characters (trichomes, modified antennae) evolved rapidly. It also suggests that myrmecophily does not require phase-like or step-wise evolution, as suggested by Wasmann (1894, 1898), except perhaps in the case of the Old World myrmecophiles.

The South African ( Diplocotidus ) and Australian myrmecophilous genera

(Diplocotes , Enasiba , Ectrephes, and Polyplocotes ) are united in a single, basal clade within the spider beetles, which supports a monophyletic Ectrephini for the Australian taxa. Diplocotidus is the only genus among all these myrmecophiles (except for the singular species Diplocotes famliaris) that bears simple 11-segmented antennae, whereas

related Australian myrmecophilous spider beetles bear moniliform or paddle-like

antennae. Previous authors (Lawrence & Reichardt 1969, Bell & Philips 2008) 148

hypothesized that Diplocotidus is likely to comprise an independent lineage of myrmecophile based on the simple antennomeres and distinctive pronotal modifications; however, this study indicates a single origin of Old World myrmecophilous taxa.

Lawrence & Reichardt further suggested that these African and Australian myrmecophiles may have evolved from ancestors that were associated with ground debris or mammal burrows. A similar hypothesis was proposed for the scarab genus

Cremastocheilus , as species in the subgenus Macropodina are collected near small rodent

burrows. Given that spider beetles are largely opportunistic scavengers, it is possible that

ancestral spider beetles utilized food sources and debris in nests for food and as a site for

oviposition. When considering the less “specialized” antennae and pronotal modifications

of Diplocotidus myrmecophily may have evolved in a step-wise fashion from less

morphologically specialized taxa to those of the Australian ectrephines.

Such a hypothesis supports Wasmann’s hypothesis that myrmecophily occurs in

phases (see Chapter 2). However, when one considers that two of the New World taxa

were most basal in the resulting phylogeny, Wasmann’s hypothesis is rejected, unless

other myrmecophilous or transitional species have gone extinct. The newly described

genus (Chapter 5) Electrognostus bears characters that are transitional between Ptinus

and Gnostus ; however, no fossil evidence exists yet that might support similar transitions

between Diplocotidus and other basal spider beetles. It is interesting to note that

antennae are not modified in the basal (New World) spider beetles, and that the highly

modified antennae appear in two groups: the Australian myrmecophiles, and separately in

Gnostus . 149

Myrmecophiles bear many plesiomorphic characters, while also having characters

that are also considered to be highly derived. The hypothesis that they evolved from

Ptinus -like ancestors is also not supported. Rather, Ptinus has evolved later from an ancestor that bore none of the myrmecophilous traits shared by myrmecophiles.

Alternatively, if one hypothesizes that the majority of spider beetles evolved from myrmecophilous ancestors, it would also imply that the bizarre myrmecophilous characters were lost in more derived lineages of the spider beetles. The highly variable morphological traits present in the spider beetles as a whole may support this idea that myrmecophily was lost in derived groups, particularly when considering the extreme forms of the pronota in many spider beetles. This is also supported by the recently described Electrognostus intermedius (see Chapter 5), which may indicate a transition between myrmecophilous and non-ant-associated spider beetles. The unique pronotal morphology that defines this species indicates that pronotal carinae, protrusions, or concavities evolved before myrmecophily, or based on these results, were maintained but slightly modified in non-myrmecophiles.

Finally, the fact that myrmecophily has evolved rampantly in many families of

Coleoptera may indicate that certain ecological pressures, particularly those associated

with specific ant host interactions, may lead to relatively fast rates of evolution (losses

and gains) of myrmecophilous characters and the respective ant-beetle interactions. The

results of this analysis further support what is known about myrmecophily within

Coleoptera, mainly that obligate myrmecophily has evolved numerous times, but the

actual behaviors associated with the presence of trichomes or other characters assumed 150

to be related to myrmecophily may be much more complex. Behavioral studies may be the only way to truly understand myrmecophily in its fullest sense.

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Chapter 5: Description of two new genera of Ptininae from Dominican amber

5.1. Abstract Two new genera, Electrognostus n. gen. and Okamnina n. gen., including three new species, Electrognostus intermedius n. sp., Okamnina carinae n. sp. and O. annae n. sp. are described and represent the first two spider beetle genera known from Dominican amber. The new genera bear characters that place them within the spider beetles

(Ptininae), although the unique pronotal structure set both of them apart from any existing or described genera within the family. Both genera bear characters similar to Ptinus

Linnaeus 1767 and Gnostus Westwood 1855. The phylogenetic significance of the new genera with regard to spider beetle evolution is discussed, and the potential usefulness of both new genera in regards to our current knowledge of the evolution ant-associated behavior in the spider beetles.

5.2. Introduction The spider beetles comprise nearly 70 described genera and close to 700 extant species that are found worldwide, although they are predominantly distributed throughout drier subtropical and temperate regions (Howe 1959). Individuals can be collected in various types of debris, where they act as scavengers feeding on decaying organic matter in leaf litter, animal nests, dung, dead wood, and stored food products. They resemble spiders

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when viewed from above, as the head is deflexed and hidden under the thorax and the antennae resemble a fourth pair of legs. Spider beetles are generally small (between 1-4 mm) and hirsute, but their body shape can be extremely variable, ranging from very compact and rounded forms (including many myrmecophiles that have, for example, trichomes positioned in pockets and modified antennae), to more elongate “bostrichid” or

“anobiid” wood-borer bodies. This morphological diversity has led to some groups being placed in their own families and continuing disagreement on the higher taxonomy for spider beetles (see Chapter 4). While considered a family by some (e.g. Belles 1984,

Downie & Arnett 1996), many also consider them to be a subfamily (e.g. Crowson 1967,

Lawrence and Newton 1995). Herein they are referred to as the Ptininae (Bouchard et al.

2011) or as spider beetles, based on discussions in Philips and Foster (2004), the phylogenetic analysis in Philips (2000) and the recent catalog of Palaearctic Coleoptera

(Löbl and Smetana 2007).

Fossil spider beetles have previously been described from various deposits that include Middle to Late Oligocene brown-coal samples (Heyden 1859, Heyden & Heyden

1866, Haupt 1956), Late Pleistocene rat nests (Spilman 1976), and Middle Pleistocene deposits (Maddy et al. 1994, Field et al. 2000). Thus far, and although known from Baltic amber for a long period of time, Belles and Vitali (2007) provide the first and only amber fossil descriptions of spider beetles, including a species of Ptinus and a new genus and species named Sucinoptinus sucini from the Baltic. The few spider beetles known from amber may be due to the lack of xylophagous (wood-boring) species. Two spider beetle genera are described herein, and are the first spider beetle representatives described from 153

Dominican Republican amber. One genus may have been associated with tree-dwelling ants in the genus Crematogaster , while the other genus represents a more bostrichoid-, wood-boring type of spider beetle. Both genera obviously belong to the spider beetles

(Ptininae), based on closely inserted antennae, a character that often most reliably separates them from other bostrichoid beetles (see Chapter 4).

5.3. Materials, methods, and descriptions Type locality and horizon : The La Toca Mines are located in the north-central region of the Dominican Republic, north of the city of Santiago de los Caballeros, in the Cordillera

Septentrional. Dominican Republic amber is now known to be younger than first claimed, and is late Early Miocene through early Middle Miocene approximately 15 to 20 million years old (Iturralde-Vinent and MacPhee, 1996). Both new genera described below were from amber collected from these mines and obtained by loan from colleagues.

Genus Electrognostus Philips & Mynhardt 2011, n. gen. (Fig. 12-14)

Type material : Holotype. Amber from La Toca Mines, Dominican Republic, compressed oval in shape, flattened on one side, and approximately 19 x 28 mm (#12642). Paratype from the same locality, trapezoidal in shape, two parallel sides 10 and 7 mm in length, remaining sides 8 and 9 mm, approximately 2.5 mm thick (#12140). Holotype and paratype deposited in the T.K. Philips collection.

Description : Form elongate, convex, covered with fine sparse setae; surface shiny.

154

Head strongly declined, barely visible from above; eyes large, positioned lateral; clypeus

subtriangular, extending forward to form medially raised angle surrounding mouthparts,

mouthparts not easily visible in anterior view. Antennae with nine antennomeres, closely

inserted on head, narrowly separated, length approximately 2/3 total length of body, last

antennomere greater than length of previous two combined, tip blunt, obliquely pointed

off center.

Pronotum approximately twice as long as wide; anterior margin raised above

head, extending to base of pronotum as two dorsolateral, approximately parallel ridges,

similar medial ridge dorsally at apical two thirds elevated; near basal third a strong

transverse declivity; basal third dorsally with semicircular concavity at middle; laterally

deeply concave in triangular shape over most of the surface.

Elytra not fused, more or less parallel-sided but slightly widening near middle,

humeral angles produced; each elytron with nine rows of fine punctures. Hindwings fully

developed.

Prosternum before coxae flat; procoxal insertions close, intercoxal process not visible, procoxae conspicuous, truncate at apex. Metasternum with coxal insertions close to midline. Abdomen with five visible ventrites; fourth ventrite reduced. Legs with coxae semi-quadrate, slightly longer than trochanters; femora and tibia elongate, tibia thin and parallel sided; five tarsomeres present, fifth elongate.

Etymology : The generic name is derived from electra (Greek, meaning “amber”) and gnostus , as the specimen most closely resembles species within the genus Gnostus . 155

Diagnosis : This genus can be recognized from other spider beetle genera by the unique shape of the pronotum that is very similar to that seen in species of Gnostus . The antennae are composed of nine antennomeres, a unique number within the New World spider beetles and seen in some species in the Australian genus Polyplocotes Westwood

(Lawrence and Reichardt 1969, Bell and Philips 2009).

Electrognostus intermedius Philips & Mynhardt. n. sp. (Fig. 12-14)

Description : Sex undetermined. Total body length about 1.5 mm. Integument cupreous, reddish-brown to dark brown.

Head very finely but scarcely punctate, with fine recumbent hairs present along clypeal edge; compound eye approximately oval in shape except slightly angulate opposite antennal insertion and with 12 ommatidia at widest diameter; antennal insertions slightly carinate between the antennae; irregular grooves present above eyes; antennae with each segment narrower at base and becoming widened at tip; antennomeres with short erect, lightly scattered setae; terminal segment approximately twice as long as others, rounded at tip; scape nearly parallel-sided , about 1.5x as long as other segments; segments 2-8 subequal in length.

Pronotum regularly punctuate with small, shallow punctures separated by distance approximately equal to two punctures, equally distributed throughout anterior third of pronotum; Elytron with fine punctures, each bearing short semi-erect seta, separated by distance approximately 2-3 times a puncture diameter; humeral angles of elytra slightly

156

produced laterally. Prosternum with visible tomentum along base, extending laterally towards dorsum.

Abdomen with fourth ventrite reduced to length approximately 1/3 of third segment. Femora slightly curved and subpedunculate, as long as straight; tibia slender tibia. Tarsi equally long, except fifth tarsomere nearly twice as long as basal four tarsomeres, claw simple.

Etymology : The specific epithet intermedius is given because the species bears characters that are intermediate between species seen in a typical spider beetles like Ptinus and those in the myrmecophilous genus Gnostus .

Additional Comments : There are two specimens which appear to be the same species, although the ability to see various parts differs between the two specimens. The overall body shape, pronotal ridges, antennae, and other observable features all appear identical.

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Figure 12. Electrognostus intermedius , n. gen., n. sp., dorsal (1-2) and ventral (3-4) view (from Philips & Mynhardt 2012)

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Figure 13. E. intermedius , lateral view (5-7); antenna (8)

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Figure 14. E. intermedius , paratype

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Genus Okamnina n. gen. (Figs. 15-16)

Description : Length small, 1.6-1.65 mm. Body elongate, roughly parallel-sided, slightly

convex, covered with sparse, long setae; integument surface shiny, not completely

obscured with setae.

Head strongly declined, vertical, barely visible in dorsal view; eyes small,

approximately oval in shape, positioned laterally, separated by antennal insertions;

clypeus raised as medial carina over mouthparts, mouthparts largely hidden. Antennae

with nine antennomeres, interantennal space narrow, space not visible.

Pronotum parallel-sided, approximately round in cross-section; anterior margin

raised above head, distinctly margined anteriorly; anterior-most edge medially

emarginate. Scutellum visible, apex broadly rounded, slightly narrowing at base.

Elytra not fused, parallel-sided, humeral angles produced; each elytron with five

visible rows of large punctures basally; long, erect setae present; hind wings fully

developed, venation not visible on exposed apical half.

Prosternum not visible; mesosternum shorter than metasternum, metasternum convex, width approximately 2x length; metepisternum somewhat broad, contacting anterolateral edge of hind coxae. Abdomen about as wide as body, slightly longer than wide, five ventrites present, sutures reduced medially, fourth ventrite reduced.

Procoxa semi-quadrate, conspicuous, projecting, approximately as long as trochanter obliquely truncate at apex; mesocoxa somewhat triangular, shorter than trochanter; metacoxa transverse and roughly rectangular, reaching metepisternum,

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trochanters conspicuous; femora elongate, subpedunculate; tarsi short and more or less

compact, five tarsomeres present, fifth elongate.

Diagnosis : This genus can be distinguished from other spider beetle genera by the unique parallel-sided and distinctly anteriorly margined pronotum. The anterior pronotal margin bears an extension over the antennae that appears bilobed in shape. This genus also has only nine, compared to the typical 11, antennomeres, which is also found in

Electrognostus Philips & Mynhardt 2011 (Philips & Mynhardt 2011), Pitnus , and also in some species of the Australian myrmecophile, Polyplocotes Westwood, 1869 (Bell &

Philips 2009).

Etymology : The generic name is derived from the word okamnina (Slovenian for

“fossil”).

Type species : Okamnina carinae n. sp . From amber of La Toca, Dominican Republic

(mid-Miocene).

Okamnina carinae n. sp . (Fig. 15)

Description: Sex undetermined. Total body length about 1.6 mm. Integument dark brown.

Head scarcely punctate, fine erect setae present on clypeal edge, frons, and between eyes; eye oval in shape, slightly narrowing near ventral-most edge, bearing up to eight small 162

ommatidia at widest diameter; antennal fossae distinctly carinate except ventrally,

antennal insertions closely inserted and separated by rounded interantennal ridge;

antennae approximately ½ the total length of body, each antennomere becoming smaller

and more compact near tip, covered with short semi-erect setae; scape wider at apex,

about twice as long as other segments; segment three about 1.5x as long as segments 4-8

and segments 4-8 subequal in length, ultimate (9 th ) segment greater than length of

previous two combined, tip blunt.

Pronotum coarsely punctate with large, irregular punctures separated by distance

< length of one puncture, concentrated near lateral edges of posterior ½ of pronotum, absent near midline, except for a few scattered punctures near well-developed anterior margin of pronotum; dorsal surface with two faint but parallel carinae extending from basal third to anterior margin, space between carinae concave and distinctly impressed medially to form shallow concavity, bilobed extension anterior to anterior margin present.

Elytra with large, coarse punctures, concentrated near basal 1/4 of elytra, gradually disappearing, finer near humeri and posterior ¾ of elytron, approximately five rows of punctures present near base, three additional rows visible in lateral view, occasionally accompanied by long erect seta; humeral angles well developed and slightly produced laterally.

Abdomen with five ventrites, sutures reduced medially; fourth ventrite reduced;

length of third ventrite approximately 3x length of penultimate (fourth).

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Figure 15. Okamnina carinae , lateral (A) and dorsal (B) views

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Femora subpedunculate, gradually increasing in width to distal end; tibia

flattened, metatibia nearly ovoid; fifth tarsomere nearly twice as long as previous four,

basal four subequal in length, claws simple, small. Legs scattered with occasional short,

semi-erect, bristle-like setae.

Etymology : The species epithet, carinae , is so named for the dorsal carinae present on the

pronotum, and separates this species from the one described following.

Okamnina annae , n. sp. (Fig. 16)

Description

Sex undetermined. Total body length approximately 1.65 mm. Integument dark brown.

Head coarsely punctate, fine erect setae scattered across clypeal edge and dorsally between antennae; eye roughly oval in shape, slightly angulate at ventral-most region, eye bearing 8-9 small ommatidia at widest diameter; antennal insertions carinate dorsally, interantennal space narrow but not clearly carinate; antennal length <1/2 length of body; scape large, slightly expanded near distal end, about 2x length of other segments; segments 3-8 subequal in length, covered in fine, short and erect setae, ultimate (9 th )

segment approximate 2x longer than previous antennomere, tip rounded.

Pronotum rugose, occasional irregular punctures scattered on disc, especially

along raised anterior margin; extended portion anterior to margin expanded to form

emarginate ridge situated over antennal insertions, narrowing behind dorsal view of eyes;

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pronotum parallel-sided with scattered short setae distributed throughout; slight concave indentation originating near base and extending approximately 2/3 to anterior edge.

Elytra with large punctures near base, decreasing suddenly in size after approximately 4 puncture widths, extending over length of elytra as finer punctures separated by single puncture diameter; five visible rows of setae transversely, nine visible dorsal rows of setae along length of elytra; setation dense at humeral angles, decreasing to fine setae accompanying fine punctures; humeral angles slightly produced.

Abdomen bearing five visible ventrites; sutures diminished medially, fourth

(penultimate) ventrite reduced to approximately ½ length of third segment, second ventrite the longest, approximately twice as long as penultimate.

Profemora slightly curved and subpedunculate, as long as tibia. Pro-, meso-, and metatarsi about equal in length, fifth tarsomere approximately twice as long as basal four, basal four subequal in length, claws simple. Legs setose, covered in fine setae.

Etymology : The species epithet, annae , is named in honor of the author’s mother, Mrs.

Anna Mynhardt.

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Figure 16. Okamnina annae , lateral (A) and dorsal (B) views

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5.4. Comparison and phylogenetic implications

5.4.1. Genus Electrognostus

Electrognostus bears characters that appear to be transitional between a more

basal ptinine, such as Ptinus Linnaeus, and Gnostus Westwood, with much stronger

affinities to the latter. Hence it may represent a sister or near sister clade to Gnostus , one

of three myrmecophilous ptinine genera known in the New World (see Lawrence and

Reichardt 1966 and Philips 1998). Gnostus was once recognized as a unique family by

Gemminger and Harold (1868). Wasmann (1894) and others placed them near many

other beetle families such as the Paussidae that include species with typical

myrmecophile characters such as glands, trichomes and variously modified antennae.

Forbes (1926) noted the similarity in wing venation between Gnostus and other species of

spider beetles, and it has since then been recognized as a spider beetle. The three species

of Gnostus are very unique within the spider beetles as all bear distinct trichomes on the

pronotum on dorsolateral longitudinal ridges. These trichomes are almost certainly

associated with glands that allow them to interact with ant hosts (see Thomas et al . 1992).

Electrognostus has a similar pronotal shape and conspicuous pronotal lateral

ridges or protrusions like that in Gnostus , but it does not have any obvious trichomes.

However, the base of the pronotum in the former is covered in a strip of tomentum that

may be associated with glands and that functions in the same manner. In the genus

Cremastocheilus Knoch (see Chapter 2), tomenta are often associated with glands

underlying the integument (Alpert 1994, Mynhardt & Wenzel 2010). While similar to

168

Gnostus in being relatively glabrous, the elytra have more abundant and finer setae on the

surface.

All extant Gnostus species also have the first three abdominal ventrites fused and

lack sutures except at the margins. In contrast to the two Gnostus species recorded from

Panama and South America, Electrognostus appears slightly closer to G. floridanus

known from Florida and the Bahamas, based on a more “typical” subpedunculate ptinine

leg shape. Both species also have elytra that are fully punctate, with punctures in distinct,

longitudinal rows. In comparison, other species of Gnostus have very flattened femorae

and tibiae (in particular G. meinerti and G. formicola ) and greatly reduced or absent

elytral punctuation .

Electrognostus also has antennae with nine antennomeres that reach beyond the

middle of the body. Species of Gnostus have only three antennomeres, and the total antennal length is very short and about equal to the length of the pronotum. Based on relative lengths, the apical antennomere in both Electrognostus and Gnostus appears to be the result of fusion of the last three antennomeres. In contrast to both groups, Ptinus have the typical 11-segmented antennae like those found in most species of spider beetles.

Reduction in antennomeres is very prevalent in species with myrmecophilous habits and there can be a great deal of variation in number as well as shape even within a single genus of ptinine (Lawrence and Reichardt 1969, and see Bell and Philips 2008 and Bell and Philips 2009). Lastly, the body length of the new species placed in Electrognostus is about 1.5 mm whereas species of Gnostus range from 1.70-2.53 mm.

169

It is possible that E. intermedius could be considered to be a member of Gnostus , but this would necessitate a very large number of modifications to the current generic definition. Hence, in particular based on the lack of lateral trichomes, the presence of a possible setal patch at the middle of the pronotal base, nine antennomeres instead of three, the more typical leg shape, and the presence of elytral punctures as found in Ptinus and other Ptininae, it is more appropriate to describe a new genus for this taxon.

5.4.2. Genus Okamnina

The new genus Okamnina appears very similar to species placed in the genus

Ptinus . Like many taxa in the latter genus, both species in the new genus Okamnina have a simple parallel-sided body shape typical of spider beetles that are found in both basal

(Philips 2000) and derived clades in phylogeny. Other Ptinus-like characters include the visible scutellum, as well as the obvious and numerous rows of elytral punctures, pedunculate (rather than flattened) femora, and the presence of fully formed hind wings.

Other characters found in Okamnina are unique and distinguish it from any other extant spider beetles known. Similar to Electrognostus , Okamnina bears reduced, 9- segmented antennae; however, the apical antennomere is rounded instead of blunt at the tip. The typical blunted shape of apical antennomeres often indicates the presence of glands that may be associated with a myrmecophilous habit. Unlike Electrognostus ,

Okamnina appears to lack any characters that would classify it as a myrmecophile; however, O. carinae bears similar dorsal pronotal ridges that may align it with Gnostus and Electrognostus . It is important to note that spider beetle genera are typically 170

distinguished from one another by pronotal characters; and, the various ridges and

concavities may not be phylogenetically informative (Bellés 1991), in part because

similar bumps or projections appear in unrelated taxa, and in part because the great

variation prevents one from making reliable homology statements.

The most unique structure of both species within Okamnina , which is particularly obvious in O. annae , is the presence of tooth-like projections near the head. In O. annae the projections are positioned on the vertex of the head, whereas they arise from the anterior edge of the pronotum in O. carinae ; however, since these structures may be slightly distorted in the amber deposits their position may be similarly placed in both taxa. These projections are not known to exist for any other spider beetles, but similar pronotal projections are found in various bostrichids, which further supports the hypothesis that Okamnina may be considered basal in spider beetle phylogeny. Based on the similarities between Okamnina and Ptinus , it can also be hypothesized that this new genus may be related to other Ptinini, which would place it among the more highly derived spider beetles in that clade (see Chapter 4).

There is no doubt that this genus is a spider beetle, based on, for example, closely inserted antennae, the lack of an apical antennal club that is typical of other bostrichoids, and the reduced penultimate abdominal segment. The latter character is common in many spider beetles; however, the combination of a reduced fourth ventrite and diffuse suture lines near the midline is typical of Gnostus . In addition, the small size closely matches that of all species of Gnostus and also of Electrognostus. The unique combination of various characters, including for example, small size; parallel-sided pronotum; tooth-like 171

projections near the head; as well as reduced penultimate ventrite and diffuse sutures

medially warrant recognition of Okamnina as a unique genus within the spider beetles, and specifically within the spider beetle tribe Ptinini.

5.4.3. Summary

A preliminary morphological analysis by Philips (2000) placed both Ptinus and

Gnostus in the same clade near the base of the spider beetle tree, but in my analysis, both of these taxa are placed in a more derived clade within the newly defined Ptinini. Based on the latter result the fossil genus Electrognostus , like Ptinus , may also represent a derived, rather than a basal lineage in the evolutionary history of the spider beetles.

Similarly, the general similarities between Okamnina and Ptinus may indicate a similar phylogenetic position.

Finally, the discovery of Electrognostus is important in that it indicates that the evolution of the distinct pronotal morphology may have occurred first in the evolution of the extant genus Gnostus . All other features, such as antennomere reduction, leg flattening, further abdominal ventrite length reduction (especially in the second ventrite), and the reduction in the size and number of elytral punctures, occurred at a later stage. It is not clear if this is a general pattern in the evolution of spider beetles or any of the other known myrmecophilous beetles, as fossils have not yet been studied or we lack fossils that might show intermediate morphologies. The intermediate morphology of this genus may indicate a transition from typical ptinines to myrmecophilous spider beetles, which would support Wasmann’s hypotheses that myrmecophily occurs in a step-wise fashion 172

towards fully myrmecophilous associations, but the genus would have to be included in a

phylogenetic analysis to test this hypothesis. This will be the goal of a future study that

will include various additional extant spider beetle taxa not included in the previous

chapter. Okamnina , on the other hand, bears no characters that would indicate a myrmecophilous habit. Given that it closely resembles more basal Ptinus-like spider

beetles, and the fact that it was deposited in amber may suggest a xylophagous habit. The

species Ptinus lichenum has been documented to bore into wood. A similar biological

association may be true for Okamnina as well.

173

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Appendix A: Morphological matrix for Cremastocheilus analysis

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Taxon Cyclidius acherontius 0000000000100000-00100000100000000000---0-00-0000000 Cyclidius elongatus 0000000000100000-00100000100000000000---0-00-0000000 Genuchinus ineptus 0100000010100002000101000101001000000---0-00-0010000 Crem. beameri 0110000000000012010102001001001001010100100100110000 C. depressus 0110200000000012010112101001201101010100100100110000 C. planatus 1 0110000000000012010112101001001001010100100100110000 C. planatus 2 0110000000000012010102101001001101010100100100110000 C. puncticollis 0110200000100-11-1000---1001001001010100100000110000 C. hirsutus 0111100000010002000102210221101011213001010000012011 C. quadricollis 1 0111100000010002000102210221101011213001010000012010 C. quadricollis 2 011110010001000200010221022110101121300101000001?010 C. saucius 1111100100010002000102210221101011213001010000012011 C. planipes 1110100000000002010102110121101011213000100000011110 C. mentalis 1110100000000002010102110121101011213000100000011110 C. stathamae 1110100000100002000102120221101011203000000010010000 C. spinifer 1110100000100002010101120221101011213000100010010000 C. lengi 1110100000100002010101120121001011213000100011010000 C. opaculus 1110100000100002010101120121101011213000100000010000 C. constricticollis 1110100010100002000101100121101011213000100000010000 C. wheeleri 0122000010000002111102100111001101112000200000010100 C. knochii 0110011001000202000101000112001101012000010100010000 C. crinitus 0110011001000302000101000112001101012000210100010000 C. mexicanus 0110011001000302000101000112201101012000210100010000 C. pulverulentus 0110011011000302000101000112201101012000210100010000 C. schaumi 0100000000000002000111100111001101010000200000002010 C. westwoodi 0100000000000002000112100111001101010000200000012010 C. quadratus 0110000000000002010112100111001101010000200000010010 C. armatus armatus 0110000000000202001101000111001101012000000100010010 C. armatus montanus 0110000000000002001101000111001101012000000100010010 C. armatus ssp 1 01102000000000020011110001110011010120000001000?2010 0110000000000202001111000111001101012000000100010010 C. armatus ssp 2 C. angularis 0110200000000002001111000111001101011000000100012010 C. tomentosus 0110210000000302000101000011101001011000210100010010 C. castaneus 0122000010001002000112100111011101011000211210012000 C. variolosus 0122200010001102000102000111011101011000211210012000 C. squamulosus 0122000000011002110102000111011101011000211200010000 C. nitens 0110000101001002010101000111011101011000211200010010 C. canaliculatus 01220000000010020001121001110111010120102111?0010000 C. harrisii 0122000101011002010102100111011101011010211210010010 C. retractus retractus 0122000000011002000111000111011101012010211210010000 C. retractus incisus 0122000000011002000101000111011101012010211210010000

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Appendix B: List of known spider beetle taxa

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Included Group placement Taxon Locality/Geography (# sp. [(new)/(previous)] examined) Costatomezium Pic 1950 Gibbiini/Gibbium Central Africa Yes

Cryptopeniculus Philips Gibbiini/Gibbium South Africa Yes 2004

Damarus Péringuey 1899 Gibbiini/Gibbium Southern Africa Yes

Gibbium Scopoli 1777 Gibbiini/Gibbium Cosmopolitan Yes

Lepimedozium Bellés Gibbiini/Gibbium South Africa Yes 1894

Meziomorphum Pic 1898 Gibbiini/Gibbium South Africa Yes

Mezium Curtis 1828 Gibbiini/Gibbium Cosmopolitan Yes

Pocapharaptinus

Akotsen-Mensah and Gibbium/Gibbium South Africa Yes

Philips 2009

Stethomezium Hinton Gibbiini/Gibbium Southern Africa Yes 1943

Sulcatogibbium Bellés Gibbiini/Gibbium Nortthwest Africa Yes 1985

Xylodes Waterhouse Ptinini/Xylodes Mauritius, Madagascar Yes 1876

Maheoptinus Pic 1903 Ptinini/Xylodes SE Asia Yes

Luzonoptinus Pic 1923 (n/a)/Xylodes Philippines/SE Asia No

Cylindroptinus Pic 1910 (n/a)/Xylodes Indonesia/SE Asia No

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Cavoptinus Pic 1931 (n/a)/Xylodes Philippines/SE Asia No

Silisoptinus Pic 1917 Ptinini/Xylodes Zanzibar/E. Africa Yes

Eutaphrimorphus Pic Ptinini/Xylodes South Africa Yes 1898

Kedirinus Bellés 1991 (n/a)/Xylodes South Pacific Islands No

Sundaptinus Bellés 1991 Ptinini/Xylodes Asia Yes

Hanumanus Bellés 1991 Ptinini/Xylodes Asia Yes

Eutaphroptinus Borowski (n/a)/Xylodes South Africa No 2009

Mediterranean/Canary Dignomus Wollaston Ptinini/Dignomus Islands; South Africa, Yes (2) 1862 Oman

Madagascar, Mauritius, Sulcoptinus Bellés 1991 (n/a)/Dignomus No Seychelles

Trymolophus Bellés (n/a)/Dignomus Madagascar No 1991

Paulianoptinus Bellés (n/a)/Dignomus Madagascar No 1991

Dignomorphus Borowski (n/a)/Dignomus/Niptus South Africa No 2009

Singularivultus Bellés (n/a)/Dignomus Central Africa No 1991

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Tropicoptinus Bellés Ptinini/Ptinus Central/South America Yes 1998

Bellesus Ozdikmen2010 Sphaericini/Ptinus Venezuela Yes

Ptinus Linnaeus 1767 Ptinini/Ptinus Cosmopolitan Yes (5)

Niptinus Fall 1905 Ptinini/Ptinus North/Central America Yes (2)

Prosternoptinus Bellés Ptinini/Ptinus Venezuela Yes 1985

Scaleptinus Borowski Tribe nov.2/Ptinus South Africa Yes 2006

Oviedinus Bellés 2010 Ptinini/Ptinus Caribbean, South America Yes

Hiekeptinus Borowski (n/a)/Ptinus South Africa No 2006

Niptus Boieldieu 1856 Sphaericini/Niptus North America, Mexico Yes (2)

Tipnus Thomson 1859 Sphaericini/Niptus Europe Yes

Eurostodes Reitter 1884 (n/a)/Niptus Europe No

Eurostoptinus Pic 1859 Ptinini/Niptus Europe Yes

Pseudeurostus Heyden Europe, North America, Sphaericini/Niptus Yes 1906 Palaearctic origin

Niptodes Reitter 1884 Ptinini/Niptus Europe Yes

Trigonogenioptinus Pic Gibbiini/Niptus Sri Lanka Yes 1937

Lapidoniptus Bellés 1981 (n/a)/Niptus Iberian Peninsula No

Pseudomezium Pic 1897 Ptinini/Niptus South Africa Yes

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Mezioniptus Pic 1944 (n/a)/Niptus China No

Niptomezium Pic 1902 Ptinini//Niptus South Africa Yes

Cyphoniptus Bellés 1991 (n/a)/Niptus Tibet upland No

Casapus Wollaston 1862 Ptinini/Casapus Canary Islands Yes (2)

Africogenius Borowski Sphaericini/Trigonogenius Uganda Yes 2000

Lachnoniptus Philips Sphaericini/Trigonogenius Virgin Islands Yes 1998

Trigonogenius Solier Sphaericini/Trigonogenius Nearctic, Neotropical Yes 1849

Piarus Wollaston 1862 Ptinini/Trigonogenius Canary Islands Yes

Chilenogenius Pic 1950 (n/a)/Trigonogenius Chile No

Sphaericus Wollaston W. African coast/Canary Sphaericini/Sphaericus Yes (3) 1854 Islands

Central/South America; Pitnus Gorham 1880 Sphaericini/Sphaericus Yes Caribbean

Stereocaulophilus Bellés (n/a)/Sphaericus Canary Islands No 1995

Neoptinus Gahan 1900 Sphaericini/Sphaericus Christmas Island Yes

Acanthaptinus Philips Gibbiini/Sphaericus Madagascar Yes 2005

Genus nov. 2 AUS Ptinini Australia Yes

Genus nov. 7 AUS Sphaericini Australia Yes

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Genus nov. 8 AUS Sphaericini Australia Yes

Genus nov. 1 SAF Tribe nov. 4 South Africa Yes

Genus nov. 3 SAF Gibbiini Peru Yes

Genus nov. 4 PER Gibbiini Peru Yes

Coleoaethes Philips 1998 Tribe nov. 1/unplaced Panama Yes

Diplocotidus Peringuey Ectrephini/unplaced South Africa Yes 1899

Fabrasia Martinez & Tribe nov. 3/unplaced South America Yes Viana 1965

Gnostus Westwood 1855 Ptinini/unplaced South America, Florida Yes

Diplocotes Westwood Ectrephini/Ectrephini Australia Yes 1869

Polyplocotes Westwood Ectrephini/Ectrephini Australia Yes 1869

Ectrephes Pascoe 1866 Ectrephini/Ectrephini Australia Yes

Enasiba Olliff 1886 Ectrephini/Ectrephini Australia Yes

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Appendix C: Morphological matrix for spider beetle analysis

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