Description of six new species of Oecetis (Trichoptera, Leptoceridae) from Vietnam Author Johanson, Kjell Arne Department of Zoology, Swedish Museum of Natural History, Box 50007, 10405 Stockholm, Sweden & kjell. arne. johanson @ nrm. se; https: // orcid. org / 0000 - 0002 - 1893 - 3429 Author Pham, Thai Hong Vietnam National Museum of Nature (VNMN) & Graduate School of Science and Technology, Vietnam Academy of Science and Technology (VAST), 18 Hoang Quoc Viet St, Cau Giay, Hanoi, Vietnam. & Faculty of Biology, Hanoi National University of Education, 136 Xuan Thuy, Cau Giay, Hanoi, Vietnam. & phamthai @ vnmn. vast. vn; https: // orcid. org / 0000 - 0002 - 4763 - 3679 Author Malm, Tobias Department of Zoology, Swedish Museum of Natural History, Box 50007, 10405 Stockholm, Sweden & tobias. malm @ nrm. se; https: // orcid. org / 0000 - 0003 - 4610 - 4086 Author Sjöberg, Tin Department of Zoology, Swedish Museum of Natural History, Box 50007, 10405 Stockholm, Sweden & tin. sjoberg @ nrm. se; https: // orcid. org / 0000 - 0002 - 2813 - 9325 text Zootaxa 2020 2020-07-17 4816 3 311 324 journal article 10.11646/zootaxa.4816.3.2 1175-5326 3954419 02EAEA41-160D-41FF-95E5-8F83E4A2BAD7 Oecetis gretae sp. nov. Figs 6–10 Diagnosis. The male of this species is distinguished from many of the Oriental and Palearctic species by the absence of honeycomb structure on pregenital tergites. It resembles Oecetis varosi in the genitalia, particularly the shape of the posterior part of the phallus and the coxopodites. Oecetis gretae is distinguished from O . varosi by the less concave anterior margin of segment IX, less rounded ventral part of segment IX in lateral view, presence of a dorsal and a ventral lobe before mid-length of each coxopodite, and a phallus that is generally more slender in lateral view. It also resembles Oecetis lata from which it is distinguished by the much smaller superior appendages, a moreslender tergum X, and coxopodites having both dorsal and ventral lobes. The shape of segment IX, tergum X, and the coxopodites also resembles those of Oecetis malickyi sp. nov. , but the coxopodites of O. gretae are distinctly broader than in O. malickyi sp. nov. and the phallus of the latter lacks the prominent, ventrally oriented apicoventral process. Description, male. Length of each forewing 5.3–6.1 mm (N = 2). Genitalia ( Figs 6–10 ) clearly higher than long in lateral view. Segment IX oriented almost vertically, ventral part widely produced and convex anteriorly; dorsal part narrowing, curving posterad; anterior margin smoothly sigmoid; acrotergite of segment IX well developed, punctate, undivided, wider than each superior appendage in dorsal view; dorsal process of segment IX minute, forming pair of semimembranous papillae; sternum without membranous area basal of coxopodites but with hemispherical plate covering bases of coxopodites in ventral view; in lateral view on each side lower posterolateral process of segment IX shallow; upper posterolateral process of segment IX cone shaped, almost as long as superior appendages, curving mesad in dorsal view; longitudinal apodeme absent. Tergum X about twice as long as superior appendages; dorsal margin slightly concave in lateral view; ventral margin irregularly membranous in lateral view; apex tuboid in lateral view; in dorsal view with wide basis and narrowing toward blunt apex, wide membranous area present around superior appendages. Superior appendages cone-shaped with rounded apices in lateral view; widely oval in dorsal view. Each gonocoxite with broad base and slender distal half curving dorsad, about as long as tergum X, unbranched, with dorsal and ventral lobes before mid-length in lateral view; dorsal and ventral margins basally parallel, distal half with dorsal margin strongly concave, ventral margin convex; in ventral view narrowing distally from base before widening sub-apically; curving mesad along its length, covered with setae; setae originating from dorsal lobe before mid-length especially long. Phallus almost as long as rest of genitalia, in retracted status with single, strongly curved internal spine originating on left near base, directed posterad before looping right posteriorly; phallobase with long apicoventral process directed strictly ventrad. Male holotype : Vietnam : Vinh Phuc Prov. , Me Linh District , stream nr 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 JN3 ( VNMN in alcohol) . Paratypes : Vietnam : Vinh Phuc Prov. , Me Linh Distr , stream near Ngoc Thanh Village , 21°23’40.1”N , 105°42’54.9”E , light trap 5.iv.2011 , loc # VN 008, leg. KA Johanson , PH Thai & TT Du , DNA voucher JQ7 ( 1 male , NHRS in alcohol) . Etymology. Gretae , named for Greta Thunberg in recognition of her environmental engagement.