Larval morphology and phylogenetic position of Micromalthus debilis LeConte (Coleoptera: Micromalthidae)

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.     

Larval morphology and phylogenetic position of Horelophopsis hanseni Satô et Yoshitomi (Coleoptera,Hydrophilidae, Horelophopsinae)

The subfamily Horelophopsinae was originally proposed as one of the earliest diverging clades of Hydrophilidae (s.s.), but its phylogenetic placement has never been tested. We describe the larva of Horelophopsis hanseni Satô et Yoshitomi, 2004 of the Horelophopsinae. Larval data are based on larval specimens collected together with adults, and unambiguously associated with them by means of DNA barcoding. We perform an analysis testing the phylogenetic position of H. hanseni based on larval and adult morphological characters. Horelophopsis hanseni is unambiguously placed within the hydrophilid subfamily Hydrophilinae and its close relationships to the genus Agraphydrus Régimbart, 1903 (Hydrophilinae, Acidocerini) is recognized. The results suggest that the subfamily Horelophopsinae is unlikely to be a basal taxon of Hydrophilidae, as originally suggested.     

Larval morphology and chaetotaxy of Macrogyrus oblongus (Boisduval, 1835) (Coleoptera: Gyrinidae)

The larvae of the grooved whirligig beetle Macrogyrus oblongus (Boisduval, 1835) are described and illustrated including detailed morphometric and chaetotaxic analyses of selected structures. Larvae of Macrogyrus Régimbart, 1882 Régimbart, M. (1882), ‘Essai Monographique de la Famille des Gyrinidae. 1re partie’, Annales de la Société entomologique de France, 51, 379–458. [Google Scholar] exhibit the characters traditionally recognised as autapomorphies of the Gyrinidae. The first instars bear egg bursters on the parietal, a potential additional autapomorphy. Putative larval autapomorphies of the tribe Dineutini are the presence of additional setae on the mandible, the absence of the seta TR2, and the presence of pore-like additional structures on the ultimate palpomeres. Macrogyrus larvae differ from those of the other known dineutine genera (Andogyrus Ochs, 1924 and Dineutus MacLeay, 1825) in the absence of a neck constriction and in the distal position of the pore LAc. Other useful characters to distinguish genera within Dineutini are the presence or absence of additional setae on the cardo and coxa, and the posterior margin of the lacinia dentate or smooth.     

Larval morphology of the weevil genus Ceutorhynchus (Coleoptera, Curculionidae) from Middle Asia

Larvae of three species of the weevil genus Ceutorhynchus (C. subtilirostris Schultze., C. viator Faust, and C. setosellus Voss) are described from Middle Asia for the first time. The larvae differ in the shape of frons, structure of the labrum, and chaetotaxy of the epicranium, frons, and lacinia. A key to the species described is given.     

On the head morphology of Grylloblattodea (Insecta) and the systematic position of the order,with a new nomenclature for the head muscles of Dicondylia

External and internal head structures of adults of Galloisiana yuasai (Grylloblattodea) are described. The results are compared with conditions found in representatives of other lower neopteran lineages, notably in Austrophasma and Karoophasma (both Mantophasmatodea). Sutures and ridges of the head capsule are discussed. A new nomenclature for head muscles is presented for the entire Dicondylia (= Zygentoma + Pterygota). Galloisiana (like its sister taxon Grylloblatta) is mostly characterized by plesiomorphic features, such as the largely unspecialized orthopteroid mouthparts, the multisegmented filiform antennae, the presence of trabeculae tentorii, the absence of muscles associated with the antennal ampullae, the presence of musculus stipitalis transversalis (0mx11) and the presence of musculus tentoriofrontalis anterior (0te2). Autapomorphies of Grylloblattodea are: (i) compound eyes composed of only 60 ommatidia or less; (ii) a lacinia with a proximal tooth; (iii) a rounded submentum; (iv) loss of musculus craniohypopharyngealis (0hy3); and (v) loss of musculus labroepipharyngealis (0lb5). The phylogenetic evaluation of 104 characters of the head yields a branching pattern with Grylloblattodea as a sister group of Mantophasmatodea in clade Xenonomia. Putative synapomorphies of both taxa are: (i) a distinct angle (more than 60°) between the submentum and the mentum; (ii) posteriorly oriented labial palpi; (iii) a flat and lobe‐like hypopharynx with a suspensorium far ventrad of the anatomical mouth opening; (iv) loss of musculus tentorioparaglossalis (0la6); and (v) a connection between the antennal ampulla and the supraoesophageal ganglion containing nuclei. Xenonomia is placed in a clade with the two dictyopteran terminals. Another monophyletic group is Embioptera + Phasmatodea. Most branches of the single tree obtained in our analysis are weakly supported. The results clearly show that more data and a much broader taxon sampling are required to clarify the phylogenetic interrelationships of the lower neopteran orders. However, our results narrow down the spectrum of possible solutions, and represent a starting point for future phylogenetic analyses, with an extensive concatenated dataset.     

Larval morphology and biology of oxycorynine weevils and the higher phylogeny of Belidae (Coleoptera, Curculionoidea)

Phylogenetic relationships among members of the family Belidae (Curculionoidea) were reconstructed through cladistic analysis using 58 characters and 17 terminals. The characters were from larval morphology (30), adult morphology (25) and biology regarding larval host-plants and feeding habits (three). They were scored for exemplar taxa in 17 genera, representing different belid subfamilies and tribes, plus two outgroup taxa in Megalopodidae and Nemonychidae. The sampled genera included all those for which larval and adult information is available, and two known only from adults. New information on the larvae and biology of two oxycorynines is provided. These are the Chilean Oxycraspedus cribricollis , whose larvae live in decayed female strobili of the gymnosperm Araucaria araucana , and Hydnorobius hydnorae from Argentina, whose larvae, described and illustrated in the present paper, develop inside the flower and fruit bodies of Prosopanche americana (Hydnoraceae), a root-parasitic angiosperm. The relationships proposed by the single optimal cladogram resulting from simultaneous analysis of all taxa and characters are recovered by one of three optimal cladograms based on the larval data set alone. The cladogram justifies a revised classification of Belidae in two sister subfamilies: Belinae (with tribes Pachyurini, Agnesiotidini and Belini) and Oxycoryninae (with tribes Oxycorynini and Aglycyderini). It summarizes larval and adult synapomorphies defining the family Belidae, subfamilies and tribes. Based on the phylogenetic tree, the evolution of biological traits is traced. Larval development in vegetative organs of conifers is ancestral in Belidae. A shift to reproductive structures characterizes the Oxycorynini, a habit which was conserved while several shifts to distantly related host-plant groups occurred.     

Study on the systematic position of Metriini based on characters of the larval head (Coleoptera: Carabidae)

Abstract. Characters of the head of larvae of Metrius contractus Eschscholtz, Ozaenini and Paussini are interpreted phylogenetically. The monophyly of Metriini + Ozaenini + Paussini is substantiated by several synapomorphies such as hyperprognathism and strong constriction of the neck. Ozaenini and Paussini together form the sister-group of Metriini. Ozaenini are paraphyletic. The monophyly of Paussini + Ozaenini excluding Pachyteles is indicated by two possible synapomorphies. Several synapomorphies are shared by Physea + Paussini. Secondary prognathism, large membranous submento-mental area and other derived features are considered autapomorphies of Paussini. Paussini excluding Platyrhopalopsis are characterized by the loss of the palpifer. The monophyly of a group which comprises Geadephaga excluding Trachypachini is suggested by several synapomorphic features. A very basal position of the metriine—paussine lineage within Carabidae is indicated by several plesiomorphic features. A hypopharyngeal filter apparatus with a dense fringe of well-arranged, long hairs is a possible autapomorphy of Anisochaeta. The results of this study do not indicate a close relationship between the metriine—paussine lineage and the tribes Brachinini and Crepidogastrini as has been suggested in recent works.     

On the systematic position of the weevil Polydrusus americanus (Gyllenhal, 1834) (Coleoptera, Curculionidae)

A North American species, Polydrusus americanus Gyll., is placed in the nominotypical subgenus of Polydrusus Germ, and is closely related to the Palaearctic species P. undatus F. and P. ruficornis Bonsd.     

On the systematic position of the family Gyrinidae (Coleoptera: Adephaga)

Various characters of adult and larval members of Adephaga and Cupedidae were analyzed, and suggest that Gyrinidae are the sister-group of the remaining Adephaga, and are not closely related to the remaining aquatic Adephaga. The aquatic families Noteridae, Amphizoidae, Hygrobiidae and Dytiscidae seem to form a well founded monophyletic unit. The following characters are considered as synapomorphies of Adephaga excluding Gyrinidae: bifurcate condition of the muscle (= M.) tentoriopraementalis inferior, reduction of hypopharynx, strongly developed prosternal process, reduction in size and specialized modification of the ventral sclerite of the mesothorax, strongly developed mesofurcal arms, a high mesopleural ridge, globular mesocoxae restricted to rotatory movements, invaginated sternum VIII (coxostemum), the strongly curved base of the median lobe of the aedeagus, which articulates with the parameres, the rotated position of the aedeagus in repose, fusion of the larval clypeolabrum with the frons and reduction of the larval lacinia. Mesal shifting of M. episterno-coxalis prothoracis, and the fusion of the apical portions of the malpighian tubules of either side are considered as synapomorphies of Adephaga excluding Rhysodidae and Gyrinidae. Lateral reduction of the meta “sternal” transverse ridge and the presence of the subcubital setal binding patch of the hind wing are considered as synapomorphic characters of Trachypachidae, Noteridae, Amphizoidae, Hygrobiidae and Dytiscidae. We postulate that the metacoxal fusion occurred independently in gyrmids and the common ancestor of Trachypachidae, Noteridae, Amphizoidae, Hygrobiidae and Dytiscidae. Consequently we consider this character state as another synapomorphy of Trachypachidae and Hydradephaga excluding Haliplidae and Gyrinidae. The following characters are considered as synapomorphies of Noteridae, Amphizoidae, Hygrobiidae and Dytiscidae: Loss of tactile setae on the head capsule, metafurcal origin on the intercoxal wall, expansion of the intercoxal wall, elongation of the subcubital setal binding patch, loss of Mm. furca-coxale anterior and posterior, reduction of the larval abdominal segments IX and X, and the shifting of the uropmphi onto the ventral side of segment VIII. Presence of M. tentorio-mandibularis and M. stipitopalpalis intemus are certainly primitive features of adult gyrinids but the distribution of these character states among most members of Adephaga is yet unclear. Chemical defence gland constituents point towards a very isolated position of Gyrinidae. The old age of the group, documented by a larva found in upper Permian deposits, may support the hypothesis of a sister-group relation-ship between Gyrinidae and the remainder of Adephaga.     

Developmental stages of the hooded beetle Sericoderus lateralis (Coleoptera: Corylophidae) with comments on the phylogenetic position and effects of miniaturization

The first detailed morphological study of larvae, pupae and adults of a species of the hooded beetles (Coleoptera: Corylophidae) – Sericoderus lateralis – is presented. Histological sectioning, scanning and transmission electron microscopy, laser confocal microscopy and 3D-computer reconstruction were used. For the first time we report that according to the morphometric data of S. lateralis, at least some corylophid beetles have three larval stages. A phylogenetic position of Corylophidae within a cucujoid-cleroid clade is confirmed, and also the placement of Sericoderini within a corlyophid subgroup, which does not include Periptycinae and Foadiini. The larvae of Sericoderus are mainly characterized by plesiomorphic features compared to those of other corylophid tribes, notably Peltinodini and Rypobiini. Morphological and developmental consequences of miniaturization are discussed. Corylophid beetles display much less specific and far-reaching morphological consequences of miniaturization compared to Ptiliidae. We report the presence of unique modifications in the neural system not shared with any other insects, such as a distinctly asymmetric supraoesophageal ganglion in first instar larva, and a total displacement of the brain to the thorax in the adult stage. A highly unusual feature of the digestive tract is the sclerotised, V-shaped ventral wall of the pharynx. Developmental and size dependent changes in the relative volume of different organs are addressed. All organ systems change allometrically in the development of S. lateralis. Allometric trends in the volume of organs confirm that the factors limiting miniaturization are the size of the neural system, associated with the number and size of neurons (most critical for first instar larva), the mass of the skeleton, the egg size, and consequently the volume of the reproductive system (for free-living insects).     

Molecular phylogeny of small brown algae,with special reference to the systematic position of Caepidium antarcticum (adenocystaceae,ectocarpales)

Nuclear ribosomal DNA (3′-SSU, ITS, 5′-LSU) and plastid-encoded (rbcL and Rubisco spacer) sequences were determined in Caepidium antarcticum and compared to homologous sequences of relatives from Ectocarpales, Scytothamnales, and other brown algae. Plastidial sequences confirmed a previous conclusions from nuclear ribosomal sequences that some taxa with stellate plastids (Asterocladon and relatives) form the closest outgroup to the Ectocarpales as yet identified. To reconcile nomenclature with the clades resolved in recent molecular studies, we propose a subdivision of the Ectocarpales in five families. Plastidial sequences support the recent proposal of Adenocystaceae, and all sequences suggest that Caepidium should be included in this family. As a further result, Geminocarpus was shown to belong to the same clade as Pylaiella and a number of other brown algae with an isomorphic life history and discoid plastids. We recognise this clade, whose correct name is Acinetosporaceae, as another family in the Ectocarpales. We also propose to unite a number of genetically related taxa, which were formely classified in different families, in an extended Chordariaceae. The remaining species of the Ectocarpales belong to Scytosiphonaceae and to Ectocarpaceae, the latter containing only Ectocarpus and Kuckuckia.     

Embryonic development of a whirligig beetle,Dineutus mellyi,with special reference to external morphology (insecta: Coleoptera,Gyrinidae)

The egg morphology and successive changes of developing embryos of the whirligig beetle, Dineutus mellyi (Adephaga: Gyrinidae) are described from observations based on light and scanning electron microscopy. The egg surface is characterized by minute conical projections covering the entire egg surface, a stalk‐like micropylar projection at the anterior pole of the egg, and a longitudinal split line along which the chorion is cleaved during the middle embryonic stages. The germ band or embryo is formed on the ventral egg surface, and develops on the surface throughout the egg period; thus, the egg is a superficial type, as is the case in most coleopteran species. A pair of lateral tracheal gills (LTGs) of the first abdominal segment originates from appendage‐like projections arising at the lateral side of pleuropodia, and the LTGs of the second to ninth abdominal segments are arranged in a row with that of the first segment. Therefore, LTGs are structures with serial homology. The paired dorsal tracheal gills (DTGs) of the ninth abdominal segment are formed on the regions just latero‐dorsal to the LTGs of this segment. Regarding the pleuropodia as the structures being homologous with thoracic legs, neither the LTGs nor DTGs are homologous with thoracic legs, but originate in the more lateral region corresponding to the future pleura of the thoracic segments. The last (10th) abdominal segment in the larva is formed by the fusion of the embryonic 10th and 11th abdominal segments. Four terminal hooks at the end of the last abdominal segment originate from two pairs of swellings on the posterior end of the embryonic 11th abdominal segment. It is proposed that the terminal hooks possibly correspond to the claws of medially fused cerci of the embryonic 11th abdominal segment. J. Morphol. 2012. © 2012 Wiley Periodicals, Inc.     

Embryonic development of Carabus insulicola (Insecta,Coleoptera, Carabidae) with special reference to external morphology and tangible evidence for the subcoxal theory

The egg morphology and successive changes in the developing embryos of the carabid ground beetle Carabus insulicola (Carabidae) are described based on light and scanning electron microscopy observations. Newly laid eggs of this species are ellipsoid and measure approximately 6.1 × 2.9 mm, before increasing to 6.6 × 3.4 mm at hatching. The egg period is about 11 days at 23°C. The egg shell is characterized by a thin fragile chorion covering a hard serosal cuticle. The embryo forms on the ventral egg surface, where it develops for the duration of the egg period. During the process of thoracic leg formation, two subcoxal rings, subcoxae‐1 and 2, are clearly discernible at the basalmost region of the leg rudiments, and these subcoxae participate in the formation of the larval pleura and sterna. The result thus provides tangible evidence for the subcoxal theory, that is, that thoracic pleura and sterna are derived from subcoxal regions. Despite the complete absence of abdominal appendages in the larvae of this species, two pairs of appendage‐like swellings, the medial and lateral ones, temporarily arise in the first eight abdominal segments during the middle of embryonic development. The medial swellings are assumed to be serially homologous with the coxal part of the thoracic leg, and they later flatten out and participate in the formation of the larval pleura (hypopleurites). In the light of the serially homologous relationships among gnathal appendages, thoracic legs, and abdominal appendage‐like swellings, we identified the subcoxal regions in both the gnathal and abdominal segments. Although, the lateral swellings soon degenerate and disappear, it is considered that the swellings originate in the abdominal subcoxae‐2 and may be homologous to the tracheal gills of larvae of Gyrinidae. Based on the embryological results, new interpretations for the constituent of gnathal appendages are proposed. J. Morphol. 274:1323–1352, 2013. © 2013 Wiley Periodicals, Inc.     

The systematic position of Brathinus Leconte and Camioleum Lewis (Coleoptera: Staphylinidae)

Brathinus and Camioleum are assigned to positions within the Omaliinae (Staphylinidae). The male genitalia of Brathinus are figured for the first time, and a key is given to the known species.     

Larval phases and ecology of Chrysolina (Pezocrosita) sahlbergiana (Coleoptera, Chrysomelidae)

Larvae of four instars are described in the little known leaf-beetle species Chrysolina sahlbergiana Jacobson from the Minusinsk Depression. Artemisia spp. is recorded as its host plant. Short setae on small scleroids distinguish the described larva from those of other species of the subgenus Pezocrosita. According to this character, this larva is closely related to larvae of species of the arcto-alpine subgenera of Chrysolina Motsch. Ch. sahlbergiana is regarded as a trans-Sayan, depression-steppe petrophilous species.     

Cephalic anatomy of Sphaeriusidae and a morphology‐based phylogeny of the suborder Myxophaga (Coleoptera)

Myxophaga are a small group of beetles, but phylogenetically crucial as one of the four coleopteran suborders. The monogeneric Sphaeriusidae, one of four myxophagan families, comprise about 20 species, most of them living in moist substrate at river edges. The morphology of the minute hemispherical adult is very insufficiently known. Consequently, we document external and internal head structures using scanning electron microscopy, microtome sections and three‐dimensional reconstructions. The results are discussed with respect to effects of miniaturization and also functional aspects, especially microphagous feeding habits. The head of Sphaerius is less affected by size reduction compared with other beetles of the same size class (e.g. larger Ptiliidae, Corylophidae). Features related to very small size are the absence of externally visible ridges and a partial shift of the brain into the prothorax. The cephalic musculature is apparently not affected. The feeding apparatus is similar to what is found in microphagous species of Polyphaga, especially in Scirtoidea and Staphyliniformia. However, in contrast to polyphagans with similar feeding habits, the hypopharyngeal longitudinal ridge (or process) of Sphaerius is strongly reduced and a fimbriate galea is lacking. The observed features are also evaluated in a cladistic analysis of larval and adult characters. The results are distinctly in conflict with branching patterns suggested by analyses of molecular data, but in agreement with previous morphological studies. In contrast to a pattern obtained in a recent molecular study – (Hydroscaphidae + (Torridincolidae + (Sphaeriusidae + Lepiceridae))) – our analyses yielded Lepiceridae as sister to the remaining Myxophaga (branch support 9), and Sphaerius as sister taxon of Hydroscaphidae (branch support 5). The monophyletic origin of the latter two taxa is supported by unusual synapomorphies of adults and larvae. Sphaerius is characterized by numerous autapomorphies of the head: a labro‐mandibular locking device, a bipartite M. frontoepipharyngalis (M9) with subcomponents oriented in the opposite direction, a deep antennal furrow, an intercalary antennomere with a structure resembling a sucking disc, a strongly elongated flagellomere 1, a compact three‐segmented antennal club, strong bundles of M. tentorioscapalis (M4) originating on the posterior head capsule, a concave anterior side of maxillary palpomere 2, and an elongated second pair of tormae posteriorly connected with a process of the hypopharyngeal suspensorium.     

The systematic position of Meruidae (Coleoptera, Adephaga) and the phylogeny of the smaller aquatic adephagan beetle families

A phylogenetic analysis of Adephaga is presented. It is based on 148 morphological characters of adults and larvae and focussed on a placement of the recently described Meruidae, and the genus‐level phylogeny of the smaller aquatic families Gyrinidae, Haliplidae and Noteridae. We found a sister group relationship between Gyrinidae and the remaining adephagan families, as was found in previous studies using morphology. Haliplidae are either the sister group of Dytiscoidea or the sister group of a clade comprising Geadephaga and the dytiscoid families. Trachypachidae was placed as the sister group of the rhysodid‐carabid clade or of Dytiscoidea. The monophyly of Dytiscoidea including Meru is well supported. Autapomorphies are the extensive metathoracic intercoxal septum, the origin of the metafurca from this structure, the loss of Mm. furcacoxalis anterior and posterior, and possibly the presence of an elongated subcubital setal binding patch. Meruidae was placed as sister group of the Noteridae. Synapomorphies are the absence of the transverse ridge of the metaventrite, the fusion of abdominal segments III and IV, the shape of the strongly asymmetric parameres, and the enlargement of antennomeres 5, 7 and 9. The Meru‐noterid clade is the sister group of the remaining Dytiscoidea. The exact position of Aspidytes within this clade remains ambiguous: it is either the sister group of Amphizoidae or the sister group of a clade comprising this family and Hygrobiidae + Dytiscidae. The sister group relationship between Spanglerogyrinae and Gyrininae was strongly supported. The two included genera of Gyrinini form a clade, and Enhydrini are the sister group of a monophylum comprising the remaining Enhydrini and Orectochilini. A branching pattern (Peltodytes + (Brychius + Haliplus)) within Haliplidae was confirmed. Algophilus, Apteraliplus and the Haliplus‐subgenus Liaphlus form a clade. The generic status of the two former taxa is unjustified. The Phreatodytinae are the sister group of Noterinae, and Notomicrus (+ Speonoterus), Hydrocoptus, and Pronoterus branch off successively within this subfamily. The search for the larvae of Meru and a combined analysis of morphological and molecular data should have high priority. © The Willi Hennig Society 2006.