Oecetis hageni, 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 : 319-322

Oecetis hageni sp. nov.

Figs 26–32

Diagnosis. The species is distinguished from many of the Oriental and Palearctic species by the presence of honeycomb structure on tergite VIII and normal tergites I–VII. In the genitalia, tergum X is not divided into upper and lower parts but forms a simple, straight and long process directed posterad and with apex curving ventrad in lateral view and tapering from mid-length to point in dorsal view. The genitalia resemble those of Oecetis purusamedha Schmid 1995 in the general shapes of segment IX, tergum X, and to some degree also the coxopodites. Oecetis hageni sp. nov. is distinguished from O. purusamedha by the more anteriorly produced segment IX in lateral view, the absence of a separate upper part of segment X, the straighter club-shaped apices of the superior appendages, and the simpler dorsal branches of the coxopodites.

Description, male. Length of each forewing 5.5–6.9 mm (N = 3). Tergum VIII covered by honeycomb structure ( Figs 26, 27 ). Genitalia ( Figs 28–32 ) much longer than tall in lateral view. Segment IX subtriangular with rounded angles in lateral view; acrotergite of segment IX forming short and narrow triangle, about as wide as long; dorsal process of segment IX minute, forming pair of minute semimembranous papillae; segment IX without ventral or dorsal membranous areas; upper posterolateral processes of segment IX short, rounded; lower posterolateral processes weakly developed; longitudinal lateral apodeme absent. Tergum X simple, not divided into upper and lower parts, as long as superior appendages; straight in lateral view, except curving ventrad at apex; narrow in dorsal view, parallel-sided from base, tapering from mid-length to pointed apex. Superior appendages originating from lower part of base of tergum X, each gradually curving slightly dorsad, with club-shaped apex setose; apex somewhat footshaped in dorsal view. Gonocoxites in lateral view each divided into a broad posteriorly pointed dorsal branch and slightly longer, slender, parallel-sided ventral branch; ventral branches wide basally in ventral view, strongly narrowing from mid-length to pointed apices curved mesad; without large setae. Phallus slightly longer than segment IX, with long internal sclerite curved to left apically and series of slender, short sclerites above and to the right of large sclerite; phallobase with wide central apicoventral plate and acute apical projection on right side.

Male holotype: Vietnam: Vinh Phuc Prov., Me Linh District, stream near Ngoc Thanh Village , 21°23’38.9”N, 105°42’ 50.7”E, light trap 4.iv.2011, loc#VN002, leg. KA Johanson, PH Thai & TT Du, DNA voucher JN4 ( VNMN in alcohol) .

Paratypes: 1 male: same data as holotype (1 male, alcohol) (DNA voucher JN6). 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 voucher JR2 (1 male, NHRS in alcohol) .

Etymology. Hageni, named for the trichopterologist Herman H. Hagen, who described Oecetis lais ( Hagen 1859) from Sri Lanka, representing the first record of Oecetis from the Oriental Region.

Figures

FIGURES 26–32. Oecetis hageni sp. nov., male holotype. 26–27, honeycomb structure on tergum VIII: 26, left lateral; 27, dorsal. 28–32, genitalia: 28, left lateral; 29, dorsal; 30, ventral; 31, phallus, left lateral; 32, phallus, ventral. Scale bar = 0.2 mm (Figs 26, 27) and 0.1 mm (Figs 28–32).