Largusoperla dewalti, Chen, 2018, Chen, 2018

Chen, Zhi-Teng, 2018, Key to the fossil genus Largusoperla (Plecoptera: Perlidae), with description of two new species from mid-Cretaceous Burmese amber, Zootaxa 4450 (4), pp. 495-500 : 496

LargUSoperla dewaltI Chen, sp. nov.

Figs. 1–4 .

Description. Macropterous; body length (excluding antennae and cerci) ca. 9.1 mm, generally brown ( Figs. 1, 2 ).

Head ( Figs. 1–3 ): Head oblate, mostly covered with a dark stigma, compound eyes dark. Antennae hairy and dark brown, with at least 29 segments. Maxillary palps not preserved; labial palps three-segmented, basal segment thickest.

Pronotum ( Fig. 3 ): Pronotum nearly trapezoidal, rugose and mostly brown, much narrower than head, anterior margin wider than posterior margin, median area not visible. Meso- and metathorax sclerotized, nearly as wide as pronotum. Legs mostly dark brown except for the pale joints; tibia with several thick ventral spines, the paired tibial spurs present; first two tarsal segments shortest with conspicuous euplantulae; apex of the claw dark sclerotized.

Wings ( Figs. 1–2 ): Wings hyaline, veins dark brown. Left forewing: length ca. 11.0 mm; ScP about threefourth of forewing length, reaching ScP+RA beyond ra-rp; apical area between anterior margin and RA with one crossvein; about nine crossveins present between ScP and the anterior margin; RP originated from about one-third of RA and with three branches; M forked at near half of the wing length; ra-rp not connected with the opposite crossvein rp-ma; CuA forked basal to the fork of M, with three branches; CuP simple; area between M and CuA with six crossveins; area between CuA and CuP with five crossveins; AA1 simple, AA2 forked. Hind wings covered by forewings, veins not visible.

Abdomen ( Fig. 4 ): Abdomen approximately ½ length of the body, generally brown, laterally with dark marks; sterna 6-8 with a pale oval mark; posterolateral margins of each segment slightly extruded. Sternum 9 strongly extended backwards, posteromedially with an elliptical hammer. Paraproct thick, hairy and finger-shaped, unevenly sclerotized with a banded pattern, apex rounded. Cerci hairy and pale,10-segmented, each segment with several dark apical bristles.

Type material. Holotype male, No. CZT-PLE-MA3. This specimen is relatively well preserved except for the apex of the antennae, forelegs and right mid-leg, and the maxillary palps. The dorsal aspect of abdomen is not clear; wings are overlapping with only the left forewing clearly visible.

Etymology. The new species is named in honor of Dr. R. Edward DeWalt, Illinois Natural History Survey, Champaign, Illinois, USA for his enthusiasm for the study of the Plecoptera and for his generous assistance to the author.

Syninclusions. Plant remains and unknown organisms.

Remarks. The new species exhibits typical head pattern, body color, similar wing venation and terminalia structures of other known species of Largusoperla but L. dewalti is easily distinguished by the finger-shaped and banded paraprocts.

Figures

FIGURE 4. Largusoperla dewalti, sp. nov. Terminalia, ventral view

FIGURE 1–3. Largusoperla dewalti, sp. nov. Adult habitus, 1, dorsal view; 2, ventral view 3, dorsal view.