The Revised Classification for Scarabaeoidea: What the Hell Is Going On?

University of Nebraska - Lincoln DigitalCommons@University of Nebraska - Lincoln Papers in Entomology Museum, University of Nebraska State 11-27-2004 The Revised Classification for Scarabaeoidea: What the Hell is Going On? Brett C. Ratcliffe University of Nebraska-Lincoln, [email protected] Mary Liz Jameson University of Nebraska State Museum, [email protected] Follow this and additional works at: https://digitalcommons.unl.edu/entomologypapers Part of the Entomology Commons Ratcliffe, Brett C. and Jameson, Mary Liz, "The Revised Classification for Scarabaeoidea: What the Hell is Going On?" (2004). Papers in Entomology. 25. https://digitalcommons.unl.edu/entomologypapers/25 This Article is brought to you for free and open access by the Museum, University of Nebraska State at DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in Papers in Entomology by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln. Published in SCARABS 15 (November 2004), pp. 3-10. Published by Coleopterists Society; online at http://www-museum.unl.edu/research/entomology/Scarabs-Newsletter.htm The Revised Classification for Scarabaeoidea: What the Hell is Going On? by Brett C. Ratcliffe and Mary Liz Jameson Systematics Research Collections W436 Nebraska Hall, University of Nebraska Lincoln, NE 68588-0514 bratcliff[email protected] and [email protected] Considering the turmoil and vast changes in the classification of the superfamily Scarabaeoidea during the last 20 years, particularly in North America, we were asked to provide an update for the readers of Scarabs wherein we offer our perspectives. Much of what follows is extracted from our scarabaeoid introduction in American Beetles (Jameson and Ratcliffe 2002). By the time this overview is printed, there may have been more changes in the classification because of the rapidly accumulating evidence supporting new hypotheses. These rapid changes are a result of intensified study of the family groups using both traditional morphological evidence combined Brett and Mary Liz with increasingly insightful The superfamily Scarabaeoidea molecular studies. While possibly is a large, diverse, cosmopolitan disruptive now, these new studies group of beetles. As a personal are exciting because, for the aside (and, of course, with no first time, we are establishing bias), these are probably the finest the higher classification of the beetles in the world. Scarabaeoids Scarabaeoidea based on evidence are adapted to most habitats, and facts rather than intuition. and they can be fungivores, This research confirms many of herbivores, necrophages, our hypotheses of classification coprophages, saprophages, and Ed. Note: Dave Hawks is but also clearly refutes others. sometimes carnivores. They are conducting DNA studies Be on the lookout for future widely distributed around the on the Scarabaeoidea publications by Team Scarab and globe, even living in the Arctic David Hawks! in animal burrows. Some scarabs exhibit parental care and sociality. Page 3 Some are myrmecophilous, is not resolved and continues termitophilous, or ectoparasitic. to be debated. The hierarchical Many possess extravagant horns, level of families and subfamilies others are able to roll into a within the Scarabaeoidea is in compact ball, and still others disarray and remains unresolved. are highly armored for inquiline In most U.S. literature prior to life. A very few are occasionally the 1970s (e.g., Arnett 1968), the agricultural pests that may Scarabaeoidea included three destroy crops (even beetles have families: Passalidae, Lucanidae, to eat!) while others are used in and Scarabaeidae. This three- the biological control of dung family system of classification was and dung flies. Scarabaeoids are the “traditional” North American popular beetles due to their large system and had several practical size, bright colors, and interesting and conceptual advantages. First, natural histories. Early Egyptians it recognized the shared, derived revered the scarab as a god, characters that unite subfamilies Jean-Henri Fabre Jean-Henri Fabre studied their within the family Scarabaeidae. behavior, and Charles Darwin Second, it provided a classification used observations of scarabs in his system that allowed easy retrieval theory of sexual selection. of hierarchical information based on the fact that subfamilies were What characterizes a part of the family Scarabaeidae scarabaeoid? (e.g., life history, morphology, larval type). Phylogenetic research The antennal club is lamellate, the indicates, however, that the family prothorax is often highly modified Scarabaeidae (in the traditional for burrowing (with large coxae, sense) is not a monophyletic usually with concealed trochantins group. Accordingly, most workers and closed cavities), the protibia now follow the 12-family system is usually dentate with a single established by Browne and Scholtz spur, the wing venation is reduced (1995, 1999) and Lawrence and and with a strong intrinsic spring Newton (1995). This system mechanism for folding, tergite 8 places emphasis on the differences forms a true pygidium and is not that separate taxa rather than concealed by tergite 7, there are the similarities that unite them. four Malpighian tubules, and larvae Whereas families, subfamilies, are scarabaeiform (cylindrical, c- and tribes in the staphylinoids and shaped). curculionoids are being combined because of shared characters (thus What is the current status of the increasing efficient data retrieval), classification? the scarabaeoids are being split into numerous families because Monophyly of the superfamily of supposed differences (thus, in Scarabaeoidea is well-founded our view, decreasing information and undisputed (Lawrence and retrieval, at least in the short term). Britton 1991). The sister group The debate concerning scarabaeoid Page 4 for the Scarabaeoidea, however, classification systems illustrates the weak phylogenetic foundation of approximately 21,000 species are the superfamily. This problem is in the subfamilies Melolonthinae, the result of a number of factors Dynastinae, Rutelinae, and including (1) lack of thorough Cetoniinae (the “higher” scarabs). study of all scarabaeoid taxa, (2) Only a few phylogenetic analyses lack of diagnostic characters for have addressed relationships of all taxa, (3) lack of phylogenetic pleurostict subtribes, genera, or study of all taxa, (4) prevailing species (Ratcliffe 1976; Ratcliffe and philosophies regarding categorical Deloya 1992; Jameson 1990, 1996, levels, and (5) emphasis in 1998; Jameson et al. 1994; Krell research on the less speciose 1993; Montreuil 2000; Paucar 2003; groups of scarabaeoids and lack Smith 2003), and only one analysis of research on the more speciose has been conducted to address groups (such as the subfamilies tribal or subfamilial relationships of Scarabaeidae including the (Browne and Scholtz 1999). Melolonthinae, Rutelinae, Dynastinae, Aphodiinae, and Historically, the superfamily Cetoniinae). Scarabaeoidea was divided into Charles Darwin two generalized groups based Within the Scarabaeoidea there on the position of the abdominal is a disparity in the knowledge spiracles; the Laparosticti and between less speciose basal Pleurosticti. Pleurostict scarabs lineages and the more speciose were characterized by having groups of “higher” Scarabaeidae. most of the abdominal spiracles For example, the family situated on the upper portion of the Trogidae includes approximately sternites (Ritcher 1969; Woodruff 300 species in four genera. 1973) and included taxa whose Excellent revisionary, larval, and adults feed on leaves, flowers and phylogenetic studies are available pollen, and whose larvae feed for this group (Baker 1968; Scholtz primarily on roots and decaying 1982, 1986, 1990, 1991, 1993; wood. Laparostict scarabs, on the Scholtz and Peck 1990). Excellent other hand, were characterized monographs are also available for by having most of the abdominal the approximately 600 species of spiracles located on the pleural Geotrupidae (Howden 1955, 1964, membrane between the tergites 1979, 1985a-b, 1992; Howden and sternites (Ritcher 1969) and and Cooper 1977; Howden and included taxa whose adults and Martínez 1978) and the Trogidae larvae feed on dung, carrion, (Vaurie 1955), and these provide hides, and feathers. The position the foundation for addressing of the spiracles, however, is not a relationships within this group. consistent character (Ritcher 1969), In comparison, the family and, in recent years, subfamilies Scarabaeidae (sensu Lawrence and tribes that were once included and Newton 1995) includes in the Laparosticti have been raised approximately 91% of the species to higher taxonomic status (family (ca 27,800) of Scarabaeoidea. and subfamily, respectively). Within the Scarabaeidae, Page 5 The composition of the characters or suites of characters. Scarabaeoidea remains a topic of debate. Lawrence and Newton Underlying the classification (1995) proposed 13 families (12 problem is, of course, the fact that found in the Nearctic, Belohinidae we are dealing with constructs is Madagascan), and Scholtz that are 200 years old and that and Browne (1996) and Browne pre-date evolutionary theory. and Scholtz (1995, 1998, 1999) Linnaean classifications were proposed 13 families (all Nearctic, based on overall morphological including Bolboceratidae; similarity rather than shared, Belohinidae was not addressed). We derived characters. Thus, some follow, with some hesitation, the groups within the scarabaeoids system of

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