At last, a Pennsylvanian stem-stonefly (Plecoptera) discovered.

Olivier Béthoux,Boris Kondratieff,Dong Ren,Bill Stark,Yingying Cui

doi:10.1186/1471-2148-11-248

Olivier Béthoux, Boris Kondratieff + Show 3 more

Open Access

https://doi.org/10.1186/1471-2148-11-248

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Abstract

BackgroundStem-relatives of many winged insect orders have been identified among Pennsylvanian fossils (Carboniferous Period). Owing to their presumed 'basal' position in insect phylogeny, stoneflies were expected to occur at this period. However, no relative has ever been designated convincingly.ResultsIn this paper, we report specimens belonging to a new fossil insect species collected from the Tupo Formation (Pennsylvanian; China). The wing venation of Gulou carpenteri gen. et sp. nov. exhibits character states diagnostic of the order Plecoptera, but lack character states shared by unequivocal representatives of the order. Derived from this identification, the delimitation of the fossil species is ascertained based on comparison of several extant stonefly species. This comparative analysis allowed a trait present in G. carpenteri gen. et sp. nov., but rarely occurring in extant species, to be documented and highlighted as atavistic. Affinities of taxa formerly proposed as putative stem-stoneflies are reconsidered in the light of the new discovery.ConclusionsGulou carpenteri gen. et sp. nov. is considered the only genuine Plecoptera reported from the Pennsylvanian. Continuing efforts on the systematics of Pennsylvanian winged insects indicate a fauna more diverse than previously appreciated. It suggests that insects already had a long, yet undocumented, history by this time.

Highlights

Stem-relatives of many winged insect orders have been identified among Pennsylvanian fossils (Carboniferous Period)
Remark: The type-species of the type-genus, Gulou carpenteri gen. et sp. nov. is distinguished from all known stonefly taxa
Gulou carpenteri Béthoux, Cui, Kondratieff, Stark & Ren, gen. et sp. nov. (Figures 1, 2) Diagnosis: Forewings: ScP reaching RA; RP originating from R at 1⁄4 of wing length; MP and CuA branched distally, with 2-3 distal branches; occurrence of an arculus between M and CuA; cross-veins numerous, unspecialized

Summary

Introduction

Stem-relatives of many winged insect orders have been identified among Pennsylvanian fossils (Carboniferous Period). Owing to their presumed ‘basal’ position in insect phylogeny, stoneflies were expected to occur at this period. The earlier entomofaunas are documented based on only a few localities of the Pennsylvanian The main components are extinct (e.g., Palaeodictyopteroidea), and stem relatives of not-so-diverse groups such as Orthoptera (i.e. grasshoppers, crickets & wetas), Odonata (i.e. dragonflies & damselflies), Grylloblattida (or -odea; i.e. ice- or rockcrawlers), and Dictyoptera (cockroaches, termites & mantises, and stem-relatives) [1,3].

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