Oecetis olahi, 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

Oecetis olahi sp. nov.

Figs 21–25

Diagnosis. The species is distinguished from many of the Oriental and Palearctic species by the absence of honeycomb structure on pregenital tergites. In the genitalia, the lower part of segment X is divided into a pair of long, slender processes widely separated and a long, slender spine-like upper part. The genitalia resemble those of Oecetis ladon Malicky & Laudee 2005 (in Malicky 2005) in the shapes of segment IX, superior appendages, and coxopodites. Oecetis olahi sp. nov. is distinguished from O. ladon by the broader and more nearly rectangular ventral incision of each coxopodite in lateral view and the presence of the pair of long, slender branches of the lower part of tergum X that are absent in O. ladon .

Description, male. Length of each forewing 5.9 mm (N = 1). Genitalia ( Figs 21–25 ) much longer than high in lateral view. Segment IX in lateral view with ventral part sub-rectangular and dorsal part slender and directed posterodorsad, almost straight, gradually widening to apex; anterior and posterior margins of ventral part almost uniformly convex; acrotergite of segment IX forming short, apically rounded triangle, about as wide as each superior appendage in dorsal view; dorsal process of segment IX minute, forming pair of widely separated semimembranous papillae; segment without ventral or dorsal membranous areas; lower posterolateral processes and upper posterolateral processes weakly developed; longitudinal lateral apodeme absent. Upper part of tergum X longer than superior appendages, lower part about as long; lower part forming pair of very slender processes originating near bases of superior appendages immediately above ventral part of segment IX; in lateral view oriented almost horizontally before bending slightly ventrad before apex, each with long, single, apical seta; upper part of tergum X longer than processes of lower part, originating from upper dorsal part of segment IX, straight in lateral view, right-curved in dorsal view. Superior appendages originating on each side at junction between dorsal and ventral parts of segment IX, gradually curving posteroventrad along their length, setose and slightly club-shaped apically. Gonocoxites each with large rectangular incision ventrally at mid-length, process basal of incision triangular in lateral and ventral views; apex uniformly rounded in lateral view, pointed in ventral view, without large setae. Phallus almost as long as rest of genitalia, with large membranous dorsal lobe having long internal sclerite and three short external sclerites apically; phallobase with long, pointed, apicoventral projection uniformly curved ventrad in lateral view, located on left side and slightly pointing to left in ventral view.

Male holotype: Vietnam: Dong Nai Prov.: Vinh Cuu District, Vinh Cuu Nature Reserve, Ma Da stream, 11°22’38.2”N, 107°03’36.7”E, 78 m, light trap 16.iv.2011, loc#VN016, leg. KA Johanson & TT Du, DNA voucher JO9 ( NHRS in alcohol) .

Etymology. Olahi, named for the trichopterologist János Oláh, in recognition of his positive impact on the knowledge of the caddisfly diversity in the Oriental region, particularly Vietnam.

Figures

FIGURES 21–25. Oecetis olahi sp. nov., male holotype, genitalia. 21, left lateral; 22, dorsal; 23, ventral; 24, phallus, left lateral; 25, phallus, ventral. Scale bar = 0.1 mm.