The thorax of the cave cricket Troglophilus neglectus: anatomical adaptations in an ancient wingless insect lineage (Orthoptera: Rhaphidophoridae)

BMC Evolutionary Biology

Research Article

Sven Bradler¹  Thomas Hörnschemeyer¹  Fanny Leubner¹ 

[1] Department of Morphology, Systematics & Evolutionary Biology, J-F-Blumenbach Institute for Zoology & Anthropology, Georg-August-University Göttingen, Göttingen, Germany;

关键词: Orthoptera;    Ensifera;    Rhaphidophoridae;    Winglessness;    Morphology;    Phylogeny;   

DOI  :  10.1186/s12862-016-0612-5

 received in 2015-09-01, accepted in 2016-02-09,  发布年份 2016

来源: Springer

【 摘 要 】

BackgroundSecondary winglessness is a common phenomenon found among neopteran insects. With an estimated age of at least 140 million years, the cave crickets (Rhaphidophoridae) form the oldest exclusively wingless lineage within the long-horned grasshoppers (Ensifera). With respect to their morphology, cave crickets are generally considered to represent a `primitive’ group of Ensifera, for which no apomorphic character has been reported so far.ResultsWe present the first detailed investigation and description of the thoracic skeletal and muscular anatomy of the East Mediterranean cave cricket Troglophilus neglectus (Ensifera: Rhaphidophoridae). T. neglectus possesses sternopleural muscles that are not yet reported from other neopteran insects. Cave crickets in general exhibit some unique features with respect to their thoracic skeletal anatomy: an externally reduced prospinasternum, a narrow median sclerite situated between the meso- and metathorax, a star-shaped prospina, and a triramous metafurca. The thoracic muscle equipment of T. neglectus compared to that of the bush cricket Conocephalus maculatus (Ensifera: Tettigoniidae) and the house cricket Acheta domesticus (Ensifera: Gryllidae) reveals a number of potentially synapomorphic characters between these lineages.ConclusionsBased on the observed morphology we favor a closer relationship of Rhaphidophoridae to Tettigoniidae rather than to Gryllidae. In addition, the comparison of the thoracic morphology of T. neglectus to that of other wingless Polyneoptera allows reliable conclusions about anatomical adaptations correlated with secondary winglessness. The anatomy in apterous Ensifera, viz. the reduction of discrete direct and indirect flight muscles as well as the strengthening of specific leg muscles, largely resembles the condition found in wingless stick insects (Euphasmatodea), but is strikingly different from that of other related wingless insects, e.g. heel walkers (Mantophasmatodea), ice crawlers (Grylloblattodea), and certain grasshoppers (Caelifera). The composition of direct flight muscles largely follows similar patterns in winged respectively wingless species within major polyneopteran lineages, but it is highly heterogeneous between those lineages.

【 授权许可】

CC BY   
© Leubner et al. 2016