Cucujiformia

Abstract: Coleoptera are generally thought to be more closely related to the Neuropteroidea than to any other group of Holometabola. Possible synapomorphies of beetles and neuropteroids are: (a) presence of a gula in the adult, (b) oblique attachment of the forewings with an enlargement of the costal field (humeral and epipleural areas of the beetle elytron), (c) form of the ovipositor, (d) structure of the stemmata (larval ocelli), and (e) absence of cruciate cervical muscles (35, 51, 64, 81, 87a). Some of these features, however, have been examined in very few Coleoptera. Mickoleit (81) concluded that the beetle ovipositor represents the plesiomorphic form of that found in neuropteroids, so that Coleoptera could not be the sister group of any particular neuropteroid order; but Hamilton (48) argued on the basis of wing venation that Coleoptera and Megaloptera are sister groups. Evolution of beetles from megalopteran-like ancestors is supported by the elytral structure in Lower Permian beetles, where the venation resembles that of a megalopteran forewing, and a hindwing from the Upper Permian, which has characteristics of both groups (20, 35, 89, 90). The postition of Strepsiptera is still unclear, but the group is usually considered to be closely related to beetles based on the following evidence:

Abstract: This book is the second offour volumes in the Handbook of Zoology series which treat the systematics and biology of Coleoptera. With approximately 350,000 described species, Coleoptera are by far the most species-rich order of insects and the largest group of animals of comparable geological age. The beetle volumes will meet the demand of modern biologists seeking to answer questions about Coleoptera phylogeny, evolution, and ecology. This second Coleoptera volume covers the remaining polyphagan taxa (apart from Phytophaga) and recently described groups not included in the first volume (covering the suborders Archostemata, Myxophaga and Adephaga, and the basal series of Polyphaga), with information on world distribution, biology, morphology of all life stages (including anatomy), phylogeny and comments on taxonomy.

Abstract: External and internal structures of the cerambycoid and triungulin larvae of Micromalthus debilis are described and compared to features found in larvae of other groups of Coleoptera. The morphological data are evaluated with respect to the systematic position of Micromalthidae. A cladistic analysis was carried out with fifty characters. Micromalthidae are not closely related to Lymexylidae (Polyphaga: Cucujiformia) but belong to Archostemata, which is confirmed as a monophyletic unit. Micromalthidae are specialized in terms of morphology and life cycle and are characterized by a considerable number of larval autapomorphies. Their sister-group relationship with Cupedidae is supported by several apomorphic features, which are probably correlated with xylobiontic habits: head transverse and strongly rounded laterally, absence of stemmata, shortened antennae, presence of sternal asperities and presence of eversible lobes of segment IX. Cupedidae is monophyletic and Priamca is the sister group of the remaining genera of Cupedidae included in the analysis. A closer relationship between Tenomerga and Rhipsideigma is supported by several larval synapomorphies. The ancestral life style of larvae of Archostemata was probably xylobiontic. This is suggested by derived groundplan features of the suborder, which are also found in larvae of non-related, wood-associated families.

Abstract: Eyes of the Coleoptera previously examined possess fused rhabdoms in all but a few species that have open rhabdoms consisting of 2 central and 6 peripheral rhabdomeres. Recent investigation of more than 70 species from about 20 families (with a total of 150,000 species) led to the conclusion that nearly one-half of all Coleoptera species possess the open-rhabdom type of eye. All of these species belong to the Cucujiformia (composed of the 5 superfamilies Cleroidea, Lymexyloidea, Cucujoidea, Chrysomeloidea and Curculionoidea, sensu Crowson, 1967), and — until now — no species of this group has been found to have fused rhabdom eyes. The open rhabdomic eye is therefore considered a synapomorphous feature (sensu Hennig, 1966) of the Cucujiformia, and this taxon is regarded as a monophyletic. From electronmicroscopic examinations of 41 Chrysomelidae species from 9 subfamilies and of 18 Cerambycidae of 3 subfamilies, the position of the central rhabdomeres (R 7, 8) relative to the peripheral rhabdomeres (R 1–6) and the direction of microvilli in the central rhabdomeres were chosen for comparison. The central rhabdomeres were found to be fused, laterally, to R 1 and R 4 in all of the species from the subfamily Chrysomelinae, but no such fusion was found in any species of the other 8 subfamilies of the Chrysomelidae, nor in any of the Cerambycidae or Bruchidae examined. Microvilli of R 7 and R 8 are parallel in Donaciinae, Criocerinae, Eumolpinae, and many Chrysomelinae, and in Lepturinae, Cerambycinae and Lamiinae (Cerambycidae) and in Bruchidae. Microvilli of both rhabdomeres are aligned in several directions in the Galerucinae, Hispinae, Clytrinae, but only inPhytodecta of the Chrysomelinae, and characteristic differences in the arrangement of microvilli were recognized among these Chrysomelidae. Microvilli were parallel in one of the central rhabdomeres, but aligned in two or more directions in the other, in species of Megalopodinae, Orsodacninae, but only inTimarcha among Chrysomelinae, and again the arrangement of microvilli was characteristic of the subfamilies of these Chrysomelidae (exception: Chrysomelinae). The central rhabdomere systems possessing microvilli of only one direction, but not fused at any level of the ommatidia with peripheral rhabdomeres, are considered symplesiomorphous for this superfamily. This simple arrangement of microvilli in many diverse groups of Chrysomelidae, Cerambycidae and Bruchidae may be regarded as the basic pattern from which the different arrangements in other subfamilies were derived. Similarities in arrangement of the microvilli (among taxa of different families) are considered to be convergences. — The results are also discussed with a view to functional properties of the rhabdomeres.