Eighteen new species of Oecetis McLachlan 1877 (Trichoptera, Leptoceridae) from New Caledonia Author Johanson, Kjell Arne * kjell. arne. johanson @ nrm. se; https: // orcid. org / 0000 - 0002 - 1893 - 3429 & * kjell. arne. johanson @ nrm. se; https: // orcid. org / 0000 - 0002 - 1893 - 3429 Author Mary, Nathalie Jeanne ETHYC’O, B. P. 13821, 98 803 Nouméa Cedex, Nouvelle-Calédonie. & ethyco 2005 @ gmail. com; https: // orcid. org / 0000 - 0001 - 8250 - 7929 Author Sjöberg, Tin * kjell. arne. johanson @ nrm. se; https: // orcid. org / 0000 - 0002 - 1893 - 3429 & tin. sjoberg @ nrm. se; https: // orcid. org / 0000 - 0002 - 2813 - 9325 Author Malm, Tobias * kjell. arne. johanson @ nrm. se; https: // orcid. org / 0000 - 0002 - 1893 - 3429 & tobias. malm @ nrm. se; https: // orcid. org / 0000 - 0003 - 4610 - 4086 text Zootaxa 2020 2020-07-07 4809 2 201 240 journal article 10.11646/zootaxa.4809.2.1 1175-5326 3934048 E697983F-7223-4009-91B4-80A401D0AB8A Oecetis flucta sp. nov. Figs 73–77 Diagnosis. This species is distinguished from many of the Australasian Oecetis species by the absence of modified tergites on segment VIII and forward. The species is unique among Oecetis in several aspects. The coxopodites form two long, slender branches, the lower branch with a short ventral process, the upper branch undulating in a vertical plane; the posterior spine is missing; and the upper posterolateral projections on each side of segment IX is strongly expanded into a long, pointed process curving slightly ventrad. Description, male. Length of each forewing 6.0– 7.1 mm (N = 3). Genitalia ( Figs 73–77 ) slightly longer than tall in lateral view. Segment IX oriented vertically, being generally drop-shaped in lateral view, except for prominent upper posterolateral process of segment IX, ventral part much longer than dorsal part in lateral view; in lateral view each side with dorsal part of anterior margin almost straight, ventral part convex; ventral half of posterior margin with tall, rounded, subtriangular, lower posterolateral process of segment IX; Upper posterolateral projection of segment IX originating immediately below superior appendages, very long, smooth, curving slightly ventrad along its length, exceeding coxopodites posteriorly; longitudinal apodemes absent; acrotergite of segment IX forming pair of almost fused, wide, irregularly wart-like clusters of punctations, each cluster slightly wider than superior appendages in dorsal view; pair of dorsal semimembranous processes of segment IX very small, egg-shaped, posteriorly oriented; membranous areas absent. Main branch of tergum X forming two lateral finger-like processes running posteroventrad and parallel to each other, rounded apically in dorsal and lateral views, each almost three times longer than superior appendages, semimembranous, without setae. Posterior spine of tergum X minute, located posterior of and as long as dorsal semimembranous processes. Superior appendages short, about one-third as long as the lobes on the main branch of tergum X, oblong and subrectangular in lateral view; oblong in dorsal view. Coxopodites each basally divided into pair of equally long, slender processes directed posterodorsad; upper branch undulating, with blunt apex; lower branch almost straight in lateral view, with short ventral process at mid-length, apex rounded; in ventral view broad, with ventral process forming mesal plate with rounded posteromesal corner. Phallus as long as coxopodites, posteriorly divided into irregular and semimembranous lobes, some with small, teeth-like processes; in ventral view anteriorly wider than central and posterior parts. Male holotype : New Caledonia , Province Sud , Plateau de Dogny , Source of Dogny River , about 900 m SE summit of Plateau de Dogny , 21.61917°S , 165.88072°E , 919 m , 25.xi–16.xii.2003 , Malaise trap , loc#046, leg. K.A. Johanson , DNA voucher JF4 . Paratypes : 1 male : New Caledonia , Province Sud , Plateau de Dogny , Source of Dogny River , about 100 S of loc 046 and nearly 1.0 km SE summit of Plateau , 21.62095°S , 165.88072°E , 917 m , 25.xi–16.xii.2003 , Malaise trap , loc#047, leg. K.A. Johanson , DNA voucher JM2 . 1 male : New Caledonia , Province Nord , Mont Panié , River Padyéém , 400 m , 20°34.122’S , 164°48.147’E , 22–28.xi.2001 , Malaise trap , loc 146 (16-2001), leg. K.A. Johanson , T . Pape, B. Viklund, DNA voucher AH5. Etymology. The Latin adjective flucta means “undulating,” referring to the undulating shape of the dorsal branch of each coxopodite.