Concavapsocus Wang 2019

Genus Concavapsocus Wang et al., 2019 Type species. Concavapsocus parallelus Wang et al., 2019. Included species. Concavapsocus parallelus Wang et al., 2019; Concavapsocus valvaculeiformus sp. nov. Revised diagnosis. Ocelli absent; antennae 23-segmented; mx2 and mx4 without sensilla; forewing subrectangular (length:width = 3:1), apical margin distinctly concave; vannal region well-developed; veins reduced, nearly parallel, with sparse setae along veins and posterior margin; R 2+3 fused with R 1 at middle of wing, distally bifurcating into R 2 and R 3; CuP and A 1 meeting at the middle of wing. Hind wing membranous, posterior margin with setae. Legs with thick setae, one coxal rasp present; tibiae with two apical spurs; tarsi three-segmented. Remarks. Concavapsocus Wang et al., 2019 is distinguished from the other Psyllipsocidae genera by its unique forewing morphology and venation. This genus exhibits a consistent forewing structure regardless of wing type: macropterous or brachypterous forms both display an inwardly concave apical margin, a well-developed vannal region, and a subrectangular outline length-to-width ratio of 3:1. In contrast, others Psyllipsocidae genera exhibit brachypterous species with rounded apices, while macropterous forms bear elongate, strip-like wings (e.g., Psyllipsocus Selys-Longchamps, 1872). In Concavapsocus, veins are reduced and nearly parallel; pterostigma, cell, and nodulus are absent, and M, CuA and A veins are unbranched, these features differ significantly from other genera: Psyllipsocus with two radial cells are present: second radial cell is either pentagonal or hexagonal in shape, and CuA branched; Khatangia with a triangular pterostigma and closed pentagonal radial cell bordered by straight R 1; in Libanopsyllipsocus, M vein bifurcated, areola postica elongate and free, CuP and A 1 converge to form a nodulus; In Globopsocus, Rs and Cu are unbranched, M vein branched. In addition, antennae, maxillary palp and hindwing can also distinguished Concavapsocus: antennae 23- segmented, with cuticular sculpture (vs. part of Psyllipsocus antennae shorter than 20-segmented); mx2 and mx4 lack sensillum (vs. Psyllipsocus mx4 without large sensillum, or with smaller ones near distal end); hindwing R and M unbranched, CuA bifurcating into CuA 1 and CuA 2 (vs. Psyllipsocus and Libanopsyllipsocus hindwing with a basal cell and branched Rs and M veins); tibiae with two apical spurs, tarsi three-segmented, preapical claws without preapical tooth (vs. Khatangia, Libanopsyllipsocus and some Psyllipsocus preapical claws with preapical tooth) (Vishnyakova 1975; Mockford 1993; Perrichot et al. 2003; Azar & Engel 2008; Azar & Nel 2011; Zhang et al. 2016; Hakim et al. 2018).