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 loyolaensi sp. nov. Figs 16–20 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 branched main branch. It particularly resembles Oecetis christinae sp. nov. and Oecetis millei sp. nov. in the slightly sigmoid shape of each coxopodite, lacking a dorsal process, but having a basimesal plate seen in ventral view. Oecetis loyolaensi sp. nov. is distinguished from both O. christinae sp. nov. and O. millei sp. nov. by the subequally long posterior spine and main branch of tergum X, the presence of a prominent triangular upper posterolateral projection of segment IX, and the phallus having a strong inner spine curving ventrad along most of its length and then angled right, and an apicoventral membranous lobe with a sclerotized apex. Description, male. Length of each forewing 4.8–5.8 mm (N = 4). Genitalia ( Figs 16–20 ) slightly longer than tall in lateral view. Segment IX oriented almost vertically, ventral part slightly longer than dorsal part; on each side anterior margin almost straight; posterior dorsolateral projection very small, triangular; posterior margin dominated by well-developed lower posterolateral plate of segment IX situated approximately at mid-height of segment IX above base of coxopodite; longitudinal apodeme absent; acrotergite of segment IX large, weak, punctate, almost half as wide half as segment IX in dorsal view; dorsal semimembranous processes of segment IX paired, minute, closely situated, wart-like; membranous areas absent. Main branch of tergum X forming two lobes apically, each as long as posterior spine and slightly exceeding superior appendages, semimembranous, straight, directed posteroventrad, with single apical seta on each lobe; pointed in lateral view; in dorsal view lobes parallel-sided, not diverging, with rounded apices. Posterior spine of tergum X originating at base of main branch, finger-like, much narrower than each lobe of main branch. Superior appendages short, oblong, almost straight, almost same shape in lateral and dorsal views. Each coxopodite slightly sigmoid shaped, distal half curving dorsad; clearly exceeding tergum X posteriorly; short basal part wide in lateral and especially ventral views, in ventral view with large basal plates slightly produced posterad, lacking large setae.. Phallus about as long as each coxopodites, tall along its length, rounded anteriorly in lateral view, posteriorly with apicodorsal and apicoventral membranous lobes, apicoventral lobe with sclerotized apex; inner spine starting from anterior base, curving gradually ventrad more than 90°, in ventral view starting centrally and running straight posteriorly before bending sharply to right. Male holotype : New Caledonia , Province Nord , Mont Panié , River Padyéém , 400 m , Malaise trap , 20°34.122’S , 164°48.147’E , 22–28.xi.2001 , loc#146 (16-2001), leg. K.A. Johanson , T . Pape, B . Viklund, DNA voucher JB3 . Paratypes : 1 male : New Caledonia , Province Nord , Wan Pwé On Stream , draining NNE side of Mont Panié , 3.9 km NW Cascade de Tao , 20°31.820’S , 164°47.016’E , 18.xii.2003 , light trap , loc#085, leg. K.A. Johanson , DNA voucher JJ7 . 1 male : New Caledonia , Province Sud , Monts Kwa Ne Mwa , on road between Nouméa and Yaté , 800 m N Pont des Japonais , 22°11.043’S , 166°43.566’E , 120 m , 7–16.xi.2003 , Malaise trap , loc#015, leg. K.A. Johanson , DNA voucher JD5 . 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 JD8 . Etymology. The species is named loyolaensi for native New Caledonian Loyola Edwin Até, known as “Fanfan,” in recognition of his help during all the field work on New Caledonia .