Largusoperla borisi, 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 : 496-498

LargUSoperla borISI Chen, sp. nov.

Figs. 5–6 .

Description. Macropterous; body length (excluding antennae and cerci) ca. 8.0 mm, generally brown ( Figs. 5, 6 ).

Head ( Fig. 5 ): Head rounded, mostly covered with a dark stigma, compound eyes dark. Antennae slender and dark brown, with about 46 segments. Maxillary palps slender and three-segmented, longer than the threesegmented labial palps.

Pronotum ( Fig. 5 ): Pronotum slightly narrower than head, rugose, mostly brown except for the pale median band, near reverse trapezoidal in shape. Meso- and metathorax sclerotized, nearly as wide as pronotum. Legs mostly dark brown except for the pale joints; tibial spurs present; first two tarsal segments shortest with conspicuous euplantulae; apex of the claw dark sclerotized.

Wings ( Figs. 5, 6 ): Wings hyaline, veins dark brown. Left forewing: length ca. 8.0 mm; ScP about three-fourth of forewing length, reaching ScP+RA beyond ra-rp; apical area between anterior margin and RA with one crossvein; about 11 crossveins present between ScP and the anterior margin; RP originated from about one-third of RA and with three branches; M forked at near apical one-third 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 four crossveins in left forewing, five in right forewing; AA1 simple, AA2 forked. Hind wings not visible.

Abdomen ( Fig. 7 ): Abdomen near half the length of the body, lateral coloration darker; posterolateral margins not extended. Sternum 9 extended backwards, hammer not clear visible. Paraproct strongly sclerotized, long triangular, inner margin concave, outer margin convex, apex obtuse. Cerci pale brown, hairy and about 10- segmented, each segment with several long apical bristles.

Type material. Holotype male, No. CZT-PLE-MA4. This specimen is mostly wizened; apex of wings not clear visible, dorsal aspect of abdomen is not clear; wings are overlapped so only the forewings are clear visible.

Etymology. The new species is named in honor of Dr. Boris Kondratieff, Colorado State University, Colorado, USA for his assistance in the author’s studies of the Plecoptera .

Syninclusions. Plant remains and unknown organisms.

Remarks. This new species also has similar head pattern, body color, wing venation and terminalia structures with other known Largusoperla species. The strongly sclerotized and sub-triangular paraprocts of the new species is most similar to that of L. arcus but can be distinguished by the concave inner margin and convex outer margin and obtuse apex of the paraprocts. The paraprocts of L. arcus have a convex inner margin, concave outer margin and sharp apex (see fig. 19 in Chen et al. 2018).

Figures

FIGURE 7. Largusoperla borisi, sp. nov. Terminalia, ventral view

FIGURE 5–6. Largusoperla borisi, sp. nov. Adult habitus, 5, dorsal view; 6, ventral view.