This article was downloaded by: [University of Arizona] On: 18 January 2013, At: 10:18 Publisher: Taylor & Francis Informa Ltd Registered in England and Wales Registered Number: 1072954 Registered office: Mortimer House, 37-41 Mortimer Street, London W1T 3JH, UK Journal of Natural History Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/tnah20 Phylogenetic trends in the Scarabaeoidea (Coleoptera) C.H. Scholtz a a Department of Entomology, University of Pretoria, Pretoria, 0002, South Africa Version of record first published: 24 Feb 2007. To cite this article: C.H. Scholtz (1990): Phylogenetic trends in the Scarabaeoidea (Coleoptera), Journal of Natural History, 24:4, 1027-1066 To link to this article: http://dx.doi.org/10.1080/00222939000770631 PLEASE SCROLL DOWN FOR ARTICLE Full terms and conditions of use: http://www.tandfonline.com/page/terms-and- conditions This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. The publisher does not give any warranty express or implied or make any representation that the contents will be complete or accurate or up to date. The accuracy of any instructions, formulae, and drug doses should be independently verified with primary sources. The publisher shall not be liable for any loss, actions, claims, proceedings, demand, or costs or damages whatsoever or howsoever caused arising directly or indirectly in connection with or arising out of the use of this material. JOURNAL OF NATURAL HISTORY, 1990, 24, 1027-1066 Phylogenetic trends in the Scarabaeoidea (Coleoptera) C. H. SCHOLTZ Department of Entomology, University of Pretoria, Pretoria 0002, South Africa (Accepted 7 October 1989) Phylogenetic trends of the states of 24 adult and 14 larval characters of the major groups of Scarabaeoidea are discussed on the basis of outgroup and ingroup comparison. Evolutionary trends within the major groups are also discussed. The following (i) adult and (ii) larval characters are discussed: (i) antennal segments, antennal sensilla, ocular canthus, ommatidium structure, epipharynx, mandibles, maxillae, labium, tentorium, trochantin, coxal cavities, mesothoracic spiracles, wing venation, metendosternite, empodium, abdominal sternites, abdominal spiracles, male genitalia, female genitalia, ovarioles, karyotype, central nervous system, spermatozoan number and malpighian tubules; (ii) antennae, fronto- clypeal suture, lateral ocelli (stemmata), labial palpi, maxillae, maxillary patpi, maxillary/mandibular stridulatory areas, labrum, epipharyngeal tormae, legs, stridulatory apparatus, spiracles, abdominal apex and central nervous system. KEYWORDS: Coleoptera, Scarabaeoidea, Dascilloidea, phylogeny, evolution. Introduction Despite several detailed comparative studies on various morphological structures of many groups Of Scarabaeoidea over the past 20 years (Ritcher 1966, 1969a, 1969b, 1969c; Ritcher and Baker 1974; Iablokoff-Khnzorian 1977; Yadav and Pillai 1979; Howden 1982; Caveney 1986; d'Hotman and Scholtz, in press, as well as many Downloaded by [University of Arizona] at 10:18 18 January 2013 general works in which scarabaeoids featured (Crowson 1955, 1981; Smith and Virkki 1978; Lawrence 1982, and in press; Lawrence and Newton 1982), and various detailed, broad phylogenetic studies of specific scarabaeoid groups (Scholtz 1986; Scholtz et al. 1987; Scholtz et al. 1988), a comprehensive review of the available liter- ature has not been attempted. Consequently, because of the availability of information on various structures and taxonomic groups in the Scarabaeoidea and because of sustained interest in the superfamily, it was felt that it was appropriate to review the available published and unpublished information. Since the main purpose of this study was to review the data figures are only provided for structures that are not commonly encountered by systematists or where different interpretations of structures are possible. The data form the basis of a set which will eventually be analysed to determine possible relationships between the major scarabaeoid groups. Definition of Scarabaeoidea Adult scarabaeoids are distinguished by: a highly modified, burrowing prothorax, 0022-2933/90 $5"00 © 1990 Taylor & Francis Ltd. 1028 C.H. Scholtz with large coxae (almost always with concealed trochantins and closed cavities) and usually dentate tibiae with only one spur; hind wings with reduced venation and strong intrinsic spring mechanism for folding; a lamellate antennal club; no hind coxal plates; the second abdominal sternite represented by a lateral portion only; the eighth tergite forming a true pygidium and not concealed by the seventh; and four malpighian tubules (Lawrence and Britton, in press). Larvae are grub-like and usually C-shaped, with well-developed antennae and legs, no urogomphi, and usually, cribriform spiracles. Major trends in the group include the reduction in the adults of the eighth pair of abdominal spiracles, movement of the spiracles dorsally or ventrally, reduction in the number of antennal segments, reduction of the aedeagus from a trilobe to a bilobe, reduction in males of the genital segment from a genital capsule to a spiculum gas- trale. In larvae there is loss of the spiracular closing apparatus, increase in antennal segments from 3 to 4, and fusion of the maxillary galea and lacinia to form a mala. Origin of the Scarabaeoidea Crowson (1955),following B6ving and Craighead (1931), proposed the Dascil- loidea as the sister group of the Scarabaeoidea, based mainly on larval characters. DasciUid larvae are similar to those of many Scarabaeoidea in that they are large, grub-like forms with a large head, long antennae, cribriform spiracles, similarly robust mandibles with well developed mola and accessory ventral process, separate galea and lacinia, and complex epipharynx and hypopharynx (Lawrence, in press). Ritcher's (1969b) reference to the supposedly homologous intersegmentalia asso- ciated with mesothoracic spiracles in adult Dascillidae and Scarabaeoidea, similarity in exocone ommatidium structure is dascilloids and Passalidae (Caveney 1986), similarity in trilobe male genitalia with a well defined genital capsule in some dascilloids and various primitive scarabaeoids (Glaresidae) (d'Hotman and Scholtz, in press), mouthparts (Nel and Scholtz, in preparation), as well as open procoxal cavities which are similar in Dascillus and Pleocomidae, lend support to this hypo- thesis. However, Lawrence and Newton (1982) and Lawrence and Britton (in press) reject this hypothesis claiming similarities between dasciUid and scarabaeoid larvae are either plesiomorphic or associated with soil-dwelling habits, and that adult dascilloids share many more important features (such as the complex prothoracic Downloaded by [University of Arizona] at 10:18 18 January 2013 interlocking device) with elateriform taxa such as Callirhipidae and Ptilodactylidae, than with scarabaeoids. However, they do not propose a more likely outgroup. An important, close similarity between Dascilloidea and Pleocoma which appears not to have been considered previously is that of the longitudinal division of the median lobe of the aedeagus (d'Hotman and Scholtz, in press). Consequently, it appears that the evidence presented for relationship between Dascilloidea and Scarabaeoidea is undoubtedly as strong as that presented against such relationship and that there seems to be little reason to deny the possibility that the Dascilloidea is the most likely outgroup of the Scarabaeoidea. Dascillid larvae differ from most scarabaeoids in having: distinct tergal plates; labrum and clypeus at least partially fused together and to the frons; a very short epicranial stem; an articulated process beneath the mandibular retinaculum; heavily sclerotized, comb-like structures on the epipharynx and hypopharynx; a strongly bilobed ligula; a reduced anal segment without anal pads; and (with some exception), urogomphi on tergum 9 (Lawrence, in press). Phylogenetic trends in the Scarabaeoidea 1029 Ancestral mode of life Crowson (1981) proposed that ancestral scarabaeoids were small, convex beetles adapted for burrowing in soil [possibly something like modern-day Glaresidae, Ochodaeidae or Bolboceratinae] where they probably fed on subterranean fungi. Larvae, which are thought to have fed on fungi too, have evolved numerous adaptations for soil-living. Adaptations to various other food sources in and on the ground led to extensive radiation of the various groups. Some of the major shifts that have taken place in larvae are toward: living and feeding in rotting wood (Passalidae, Lucanidae); feeding on animal remains (Trogidae); feeding on arboreal fungi, or associated with social insects (Ceratocanthidae); feeding on living plant roots (Pleocomidae, some derived groups), humus (many derived groups) and herbivore dung (Scarabaeinae, Aphodiinae, some Geotrupidae). In many cases adults feed in similar situations on similar sources of food to those of the larvae. The most sig- nificant changes away from this situation are found in groups in which adults do not feed (Pleocomidae, DiphyUostomatidae) or in the derived groups in which adults have turned to feeding on foliage and fruit (Melolonthinae, Rutelinae, Cetoniinae), or to carnivory (Cetoniinae). The above hypothesis is consistent with the