Xing-Ke Yang

Anti-predator defence drives parallel morphological evolution in flea beetles

Complex morphological or functional traits are frequently considered evolutionarily unique and hence useful for taxonomic classification. Flea beetles (Alticinae) are characterized by an extraordinary jumping apparatus in the usually greatly expanded femur of their hind legs that separates them from the related Galerucinae. Here, we examine the evolution of this trait using phylogenetic analysis and a time-calibrated tree from mitochondrial (rrnL and cox1) and nuclear (small subunits and large subunits) genes, as well as morphometrics of femora using elliptic Fourier analysis. The phylogeny strongly supports multiple independent origins of the metafemoral spring and therefore rejects the monophyly of Alticinae, as defined by this trait. Geometric outline analysis of femora shows the great plasticity of this structure and its correlation with the type and diversity of the metafemoral springs. The recognition of convergence in jumping apparatus now resolves the long-standing difficulties of Galerucinae–Alticinae classification, and cautions against the value of trait complexity as a measure of taxonomic significance. The lineage also shows accelerated species diversification rates relative to other leaf beetles, which may be promoted by the same ecological factors that also favour the repeated evolution of jumping as an anti-predation mechanism.

Evolutionary constraints in hind wing shape in Chinese dung beetles (Coleoptera: Scarabaeinae).

This study examines the evolution hindwing shape in Chinese dung beetle species using morphometric and phylogenetic analyses. Previous studies have analyzed the evolution of wing shape within a single or very few species, or by comparing only a few wing traits. No study has analyzed wing shape evolution of a large number of species, or quantitatively compared morphological variation of wings with proposed phylogenetic relationships. This study examines the morphological variation of hindwings based on 19 landmarks, 119 morphological characters, and 81 beetle species. Only one most parsimonious tree (MPT) was found based on 119 wing and body characters. To better understand the possible role of the hindwing in the evolution of Scarabaeinae, additional phylogenetic analyses were proposed based on the only body features (106 characters, wing characters excluded). Two MPT were found based on 106 body characters, and five nodes were collapsed in a strict consensus. There was a strong correlation between the morphometric tree and all phylogenetic trees (r>0.5). Reconstructions of the ancestral wing forms suggest that Scarabaeinae hindwing morphology has not changed substantially over time, but the morphological changes that do occur are focused at the base of the wing. These results suggest that flight has been important since the origin of Scarabaeinae, and that variation in hindwing morphology has been limited by functional constraints. Comparison of metric disparity values and relative evolutionary sequences among Scarabaeinae tribes suggest that the primitive dung beetles had relatively diverse hindwing morphologies, while advanced dung beetles have relatively similar wing morphologies. The strong correlation between the morphometric tree and phylogenetic trees suggest that hindwing features reflect the evolution of whole body morphology and that wing characters are suitable for the phylogenetic analyses. By integrating morphometric and cladistic approaches, this paper sheds new light on the evolution of dung beetle hind wings.

The thorax of Mantophasmatodea, the morphology of flightlessness, and the evolution of the neopteran insects

Mantophasmatodea was described as a new insect order in 2002. Since then, this small group of wingless insects has developed into one of the best investigated insect taxa. Nevertheless, many aspects of mantophasmatodean morphology as well as their evolutionary relationships remain ambiguous. To determine the phylogenetic relationships of Mantophasmatodea based on an extended character set and to elucidate possible morphological adaptions towards flightlessness, we investigated the thoracic morphology of two species, Austrophasma caledonensis and Mantophasma sp. The morphological similarity between these two species is striking and no differences in musculature were found. The mantophasmatodean thorax strongly resembles that of ice crawlers (Grylloblattodea), especially with respect to the presence of pleural processes in the meso‐ and metathorax, branched furcae in all segments, and similar muscle equipment. In a cladistic analysis containing all major lineages of Neoptera, the monophyly of Polyneoptera is supported by the presence of an anal fan and several modifications of the wing joint. Within Polyneoptera, a sister‐group relationship between stoneflies and the remaining Polyneoptera is supported. A clade comprising Mantophasmatodea and the Grylloblattodea gains strong support from thoracic morphology and can be considered assured. Potential thoracic apomorphies include prothoracic paracoxal invaginations, pterothoracic pleural arms that originate from the epimeron, and a unique metathoracic sterno‐coxal musculature. The monophyly of Orthoptera and Dictyoptera is further supported while the deeper polyneopteran nodes remain unresolved. Among the wingless taxa investigated we found few general morphological adaptations whereas, in other aspects, especially in the musculature, strong differences could be observed. However, much more research on the strongly neglected topic of flightlessness is required to make reliable statements.

On the phylogeny and evolution of Mesozoic and extant lineages of Adephaga (Coleoptera, Insecta)

The relationships of extant and extinct lineages of Adephaga were analysed formally for the first time. Emphasis is placed on the aquatic and semiaquatic groups and their evolution in the Mesozoic. †Triadogyrus and †Mesodineutus belong to Gyrinidae, the sister group of the remaining families. †Triaplidae are the sister group of the following groups (Haliplidae, Geadephaga, Dytiscoidea incl. †Liadytidae, †Parahygrobiidae and †Coptoclavidae [major part]). The lack of a ventral procoxal joint and a very short prosternal process are plesiomorphies of †Triaplidae. †Coptoclavidae and †Timarchopsinae are paraphyletic. †Timarchopsis is placed in a geadephagan clade. In contrast to other coptoclavids, its metathorax is close to the condition found in Haliplidae, with a complete transverse ridge and coxae with large plates and free mesal walls. †Coptoclavidae s.str., i.e. excl. †Timarchopsis, is a dytiscoid subgroup. The mesal metacoxal walls are fused, the coxal plates are reduced, and the transverse ridge is absent. †Stygeonectes belongs to this dytiscoid coptoclavid unit and is therefore misplaced in †Timarchopsinae. †Liadytidae belongs to a dytiscoid subgroup, which also comprises the extant families Aspidytidae, Amphizoidae, Hygrobiidae and Dytiscidae. †Parahygrobia is the sister group of Hygrobiidae. The larvae are characterized by a broad gula, the absence of the lacinia, retractile maxillary bases and very long urogomphi set with long setae. †Liadytiscinae is the sister group of extant Dytiscidae. There is no support for a clade †Eodromeinae and for Trachypachidae incl. †Eodromeinae. †Fortiseode is nested within Carabidae. The exclusion of fossil taxa has no effect on the branching pattern. The evolution of Adephaga in the Mesozoic is discussed. Possible reasons for the extinction of †Coptoclavidae are the rise of teleost fish and the competition of Gyrinidae and Dytiscidae, which possess efficient defensive glands and larval mandibular sucking channels.

Septiventeridae, a new and ancestral fossil family of Scarabaeoidea (Insecta: Coleoptera) from the Late Jurassic to Early Cretaceous Yixian Formation

Morphologically, Scarabaeoidea is one of the best-studied groups of beetles. However, the incomplete preservation of presently known fossils is a fundamental problem in the interpretation of extinct species of the superfamily. Wing venation has long been recognized as a valuable character system in taxonomic and phylogenetic analyses. However, to date hind wing features of scarab fossils have not been analysed using geometric morphometrics. A new genus and a new species, Septiventer quadridentatus gen. et sp. nov., is described and illustrated and assigned to a new scarabaeoid family Septiventeridae fam. nov., based on one well-preserved specimen from the Yixian Formation of Liaoning Province, China. The phylogenetic position of Septiventer is inferred based on 68 morphological characters using a cladistic approach. Additionally, based on a geometric morphometric analysis of the hind wing of Septiventer, the structural affinities of 161 scarabs and six outgroup species is analysed, using 261 wing landmarks. Septiventeridae is identified as the sister group of the remaining Scarabaeoidea, with Glaresidae and Trogidae as the next branches. Consequently, it is crucial for an understanding of the early diversification of the superfamily, and for the reconstruction of early evolutionary transformations in the group. Septiventeridae differs strongly from most ‘modern’ lineages in wing shape. However, the structural affinity of the hind wings of Septiventeridae, Glaresidae and Trogidae are robustly supported by the results from morphometrics. This fits well with the phylogenetic hypothesis based on the general character set and strongly suggests that this wing pattern is closest to the scarabaeoid groundplan. The morphological features suggest good flying abilities of Septiventer, that it might have been active during the daytime, processed soft food, and was less active in digging tunnels than extant, more specialized dung beetles. http://zoobank.org/urn:lsid:zoobank.org:pub:B0076219-3F4C-4E3D-8054-7DA855E0D8A4

New fossil evidence of the early diversification of scarabs: Alloioscarabaeus cheni (Coleoptera: Scarabaeoidea) from the Middle Jurassic of Inner Mongolia, China

Abstract  Scarabaeoidea are known from the Lower Jurassic and may have originated in the Triassic based on fossil evidence and phylogenetic research. However, the early diversification of Scarabaeoidea remains unclear due to the lack of high‐quality fossil evidence. Here we describe an exceptionally well‐preserved new fossil of Scarabaeoidea, Alloioscarabaeus cheni gen. et sp. nov from the Middle Jurassic Jiulongshan Formation of Inner Mongolia, China. Based on a morphometric analysis using 17 landmarks of the hind wing of Alloioscarabaeus and 10 scarabaeoid families, we found that Alloioscarabaeus cheni gen. et sp. nov clearly does not belong to any of the known scarabaeoid families and, consequently, is a new family, Alloioscarabaeidae fam. nov., was erected. The discovery of Alloioscarabaeus brought further evidence for the early diversification of major scarab lineages which could allow more detail in the palaeobiogeography of the Scarabaeoidea and Northeast of China which might be one of the originating places or an important radiation place during the evolution of Scarabaeoidea. Alloioscarabaeidae were very likely not good diggers and might have fed on decaying organic materials. Based on the evidence we have now, we tend to believe that most families and some subfamilies of Scarabaeoidea were present in the Jurassic period.

New fossil species of ommatids (Coleoptera: Archostemata) from the Middle Mesozoic of China illuminating the phylogeny of Ommatidae

BackgroundOmmatidae is arguably the “most ancestral” extant beetle family. Recent species of this group are only found in South America and Australia, but the fossil record reveals a much broader geographical distribution in the Mesozoic. Up to now, thirteen fossil genera with more than 100 species of ommatids have been described. However, the systematic relationships of the extant and extinct Ommatidae have remained obscure. Three constraint topologies were designed based on Kirejtshuk’s hypothesis, enforced the monophyly of Tetraphalerus + Odontomma, Pareuryomma + Notocupes and both respectively.ResultsIn this study, four new species, Pareuryomma ancistrodonta sp. nov., Pareuryomma cardiobasis sp. nov., Omma delicata sp. nov., and Tetraphalerus decorosus sp. nov., are described. Based on well-preserved fossil specimens and previously published data the phylogenetic relationships of extant and extinct lineages of Ommatidae were analyzed for the first time cladistically. Based on the results we propose a new classification with six tribes of Ommatidae: Pronotocupedini, Notocupedini, Lithocupedini, Brochocoleini, Ommatini and Tetraphalerini. These taxa replace the traditional four subfamilies.ConclusionThere is good support for the monophyly of the ingroup. Notocupedini, as defined by Ponomarenko, are paraphyletic. Notocupoides + Eurydictyon are the sister group of the remaining fossil and extant ommatids. Together they form the clade Pronotocupedini. Notocupedini and Lithocupedini are the next two branches. The tribe Brochocoleini is the sister group of a clade comprising Tetraphalerini and Ommatini.

Evolutionary patterns of hind wing morphology in dung beetles (Coleoptera: Scarabaeinae).

The shape of wings can be a good predictor of adaptations to different selective pressures and the value of wing features in taxonomy and phylogeny has long been recognized. In our investigation of the hind wing evolution of dung beetles (Scarabaeinae) we use geometric morphometrics combined with a cladistic approach. The variations of entire hind wings and of three specific regions of 80 dung beetle species were investigated using 19 landmarks and outline data. Extensive evidence indicates that the wing as a whole and the three separate regions were under different selective pressures. The detailed evolutionary patterns of the three regions and the reconstruction of the ancestral forms were computed by mapping the geometric morphometrics data onto a tree based on a cladistic character analysis.

Suprageneric systematics of flea beetles (Chrysomelidae: Alticinae) inferred from multilocus sequence data

Recent phylogenetic studies of flea beetles (Alticinae) based on morphological or molecular data have focused on the relationship and possible paraphyly with respect to the closely related Galerucinae, while the supra-generic classification mainly dates back to the 19th century. Here, phylogenetic analysis was performed on DNA sequences for two mitochondrial (rrnL and cox1) and two nuclear (SSU and LSU rRNA) genes from 158 genera and 165 species that cover most suprageneric groups of flea beetles proposed in the older literature. Various alignment strategies and tree search methods were used to test the stability of major clades. Besides confirmation of the placement of several alticine lineages within Galerucinae, a preliminary framework for classification of the main alticine clades was obtained. It is proposed to recognize 18 groups of genera based on well-supported nodes. These include the Altica, Amphimela, Aphthona, Blepharida, Chabria, Chaetocnema, Dibolia, Disonycha, Griva, Lactica, Longitarsus, Manobia, Monoplatus, Nisotra, Oedionychis, Pentamesa, Phygasia and Pseudodera groups. These groups provide a novel perspective to the existing classification. The analysis of 14 morphological characters used in the traditional classification of Alticinae and Galerucinae revealed high levels of homoplasy with respect to the DNA-based tree, but significant hierarchical structure in most of them. Even if not unique to any particular group of genera, these traits largely corroborate the groupings established with DNA sequences.

A Second New Species of Ice Crawlers from China (Insecta: Grylloblattodea), with Thorax Evolution and the Prediction of Potential Distribution

Modern grylloblattids are one of the least diverse of the modern insect orders. The thorax changes in morphology might be associated with the changes of the function of the forelegs, wing loss, changes in behavior and adaptation to habitat. As temperature is the main barrier for migration of modern grylloblattids, the range of each species is extremely limited. The potential distribution areas of grylloblattids remain unclear. A second new species of ice crawlers (Insecta: Grylloblattodea), Grylloblattella cheni Bai, Wang et Yang sp. nov., is described from China. The distribution map and key to species of Grylloblattella are given. A comparison of the thorax of extant and extinct Grylloblattodea is presented, with an emphasis on the pronotum using geometric morphometric analysis, which may reflect thorax adaptation and the evolution of Grylloblattodea. Potential global distribution of grylloblattids is inferred. Highly diversified pronota of extinct Grylloblattodea may reflect diverse habitats and niches. The relatively homogeneous pronota of modern grylloblattids might be explained by two hypotheses: synapomorphy or convergent evolution. Most fossils of Grylloblattodea contain an obviously longer meso- and metathorax than prothorax. The length of the meso- and metathorax of modern grylloblattids is normally shorter than the prothorax. This may be associated with the wing loss, which is accompanied by muscle reduction and changes to the thoracic skeleton system. Threats to grylloblattids and several conservation comments are also provided.