Oecetis rostrata, Johanson & Mary & Sjöberg & Malm, 2020

Johanson, Kjell Arne, Mary, Nathalie Jeanne, Sjöberg, Tin & Malm, Tobias, 2020, Eighteen new species of Oecetis McLachlan 1877 (Trichoptera, Leptoceridae) from New Caledonia, Zootaxa 4809 (2), pp. 201-240 : 213

Oecetis rostrata sp. nov.

Figs 31–35

Diagnosis. The species is distinguished from many of the Australasian Oecetis species by the absence of modified tergites on segment VIII and forward. It resembles other Oecetis species by having simple and slightly sigmoid or undulating coxopodites in lateral view and tergum X divided into a simple dorsal posterior spine and a bilobed main branch. It particularly resembles Oecetis christinae sp. nov. in the shape of the coxopodites being divided into a broad basal part and a narrower distal part that originates from the ventral apex of the basal part, the two species also have a mesal plate originating from the dorsal margin at mid-length of the coxopodites, and the phallus has a short spine dorsally at the posterior end. In O. rostrata sp. nov. the mesal plate on the dorsal margin of each coxopodite is triangular, while that of O. christinae sp. nov. is rounded, the coxopodites of O. rostrata sp. nov. are generally taller in lateral view, compared to those of O. christinae sp. nov., and the main branch of tergum X is narrow along its length in lateral view, not dilated as in O. christinae sp. nov.

Description, male. Length of each forewing 7.8 mm (N = 1). Genitalia ( Figs 31–35 ) clearly longer than tall in lateral view. Segment IX oriented almost vertically, ventral part clearly longer than dorsal part in lateral view; on each side anterior margin dorsally almost straight, ventrally convex; posterior margin dominated by well-developed upper and lower posterolateral processs of segment IX, situated immediately below superior appendages and near mid-height of coxopodites, respectively, both short, triangular; longitudinal apodeme slender, running between anterior and posterior margins of segment IX at mid-height of coxopodite base; acrotergite of segment IX divided into pair of punctate warts, each about half as wide as superior appendages in dorsal view; dorsal semimembranous processes of segment IX paired, oblong, closely situated; membranous areas absent. Main branch of tergum X forming two lobes, each reaching slightly farther posteriorly than posterior spine, about twice as long as superior appendages, semimembranous, slightly curving ventrad, without setae; apex pointed in lateral view; in dorsal view each lobe tapering towards narrowly rounded apex, directed posterad. Posterior spine of tergum X originating at base of main branch, slender, finger-like, as thick as main branch in lateral view, almost straight. Superior appendages short, oblong in lateral and dorsal views. Each coxopodite in lateral view almost straight, basally wide and parallel-sided to beyond mid-length, almost uniformly slender distal part originating from ventral apex of anterior part; in lateral view basal-most dorsal part with triangular mesal plate at mid-length; distal part almost straight; clearly exceeding tergum X posteriorly; in ventral view basal-most part wide, with large, triangular basomesal plates pointing posterad; few large setae present on coxopodite. Phallus about as long as each coxopodite, in lateral view uniformly tall along its length, anterior margin rounded, posteriorly with membranous tissue not expanded; long, slender inner spine starting from left part of anterior apex, running along anterior margin and posteriorly along right margin before crossing to left side and curving ventrad at apex; short basally tall apicodorsal spine present, slightly curving ventrad beak-shaped in lateral view.

Male holotype: New Caledonia, Province Sud, Mont Kwa Ne Mwa , on road between Nouméa and Yaté, 2.0 km E Pic Mouirange, 22°12.356’S, 166°40.798’E, 220 m, 16–30.xi.2003, Malaise trap, loc#014, leg. K.A. Johanson, DNA voucher JA2 .

Etymology. The Latin adjective rostrata means “beaked,” referring to the beak-like spine on the posterior end of the phallus.

Figures

FIGURES 31–35. Genitalia of Oecetis rostrata sp. nov., male holotype. 31, left lateral; 32, dorsal; 33, ventral; 34, phallus, left lateral; 35, phallus, ventral.