Oecetis lata, Johanson & Pham & Malm & Sjöberg, 2020

Johanson, Kjell Arne, Pham, Thai Hong, Malm, Tobias & Sjöberg, Tin, 2020, Description of six new species of Oecetis (Trichoptera, Leptoceridae) from Vietnam, Zootaxa 4816 (3), pp. 311-324 : 312-314

Oecetis lata sp. nov.

Figs 1–5

Diagnosis. The male of this species is distinguished from many of the Oriental and Palearctic species by the absence of honeycomb structure on pregenital tergites V–VIII. It resembles Oecetis varosi Oláh 2013 in the genitalia, particularly the shape of the phallus and the coxopodites. Oecetis lata sp. nov. is distinguished from O. varosi by the shorter ventral part of segment IX, broader tergum X in lateral and dorsal views, and the larger and more triangularly shaped superior appendages in lateral view. It generally resembles Oecetis tripunctata ( Fabricius 1793) in the shape of tergum X, superior appendages, the coxopodites, and the phallus. It is distinguished from O. tripunctata by the superior appendages being shorter than tergum X, the broader coxopodites in lateral view, the longer ventral process, and the straight internal spine of the phallus. It also resembles Oecetis gretae sp. nov. from which it is distinguished by the much larger superior appendages, taller tergum X, and coxopodites lacking branches.

Description, male. Length of each forewing 6.0– 6.8 mm (N = 5). Genitalia ( Figs 1–5 ) slightly higher than long in lateral view. Segment IX oriented almost vertically, ventral part slightly produced anteriorly; dorsal part rectilinear; anterior margin almost straight; acrotergite of segment IX well developed, punctate, undivided, almost as wide as each superior appendage in dorsal view; dorsal process of segment IX minute, forming single semimembranous papilla, wart-like; sternum with large rhomboid membranous area basal of coxopodites; lower posterolateral process of segment IX very shallow; posterior dorsolateral processes of segment IX short and right-angled; longitudinal apodeme absent. Tergum X slightly longer than superior appendages, in dorsal view wide along its length, slightly narrowing posteriorly to truncate apex; dorsal margin almost straight in lateral view; ventral margin membranous and convex in lateral view; apex small and rectangular in lateral view; upper part tergum X absent. Superior appendages wide and long, fused with tergum X, and almost covering tergum X in lateral view; oval in dorsal view. Each coxopodite slender, 1.5X as long as tergum X, unbranched, in lateral view dorsal margin shallowly W-shaped, ventral margin sub-straight; dorsally expanded into subtriangular swelling shortly beyond mid-length, apex almost straight; in ventral view sinuous and slightly tapering, especially beyond convexity at 2/3 length, elongate setae arising at lateral margin of and basal of convexity. Phallus slightly longer than superior appendages, with single, straight internal spine oriented diagonally and angled from left to right posteriorly; phallobase with long apicoventral process directed ventrad.

Male holotype: Vietnam: Vinh Phuc Prov.: Me Linh Distr, stream near Ngoc Thanh Village , 21°23’40.1”N, 105°42’54.9’E, light trap 5.iv.2011, loc#VN008, leg. KA Johanson, PH Thai & TT Du, DNA voucher JQ8, VNMN (in alcohol) .

Paratypes: Vietnam: Vinh Phuc Prov., Me Linh District, stream near Ngoc Thanh Village , 21°23’02.3”N, 105°42’44.5”E, light trap 4.iv.2011, loc # VN 003, leg. KA Johanson, PH Thai & TT Du, DNA vouchers JR1, JR5 (2 males, NHRS in alcohol). Me Linh District, stream near Ngoc Thanh Village, Melinh Station for Biodiversity , 21°23’28.2”N, 105°42’46.7”E, 233 m, Malaise trap 4–12.iv.2011, loc # VN 001, leg. KA Johanson, PH Thai & TT Du, DNA voucher JN5 (1 male, NHRS in alcohol). Me Linh District, stream nr Ngoc Thanh Village , 21°23’38.9”N, 105°42’ 50.7”E, light trap 4.iv.2011, loc # VN 002, leg. KA Johanson, PH Thai & TT Du, DNA voucher JQ9 (1 male, NHRS in alcohol) .

Etymology. Latin adjective lata , meaning “broad” or “wide,” referring to the shape of the superior appendages in lateral view.

Figures

FIGURES 1–5. Oecetis lata sp. nov., male holotype, genitalia. 1, left lateral; 2, dorsal; 3, ventral; 4, phallus, left lateral; 5, phallus, ventral. Scale bar = 0.1 mm.