The long-horned caddisfly genus Oecetis (Trichoptera: Leptoceridae) in Australia: two new species groups and 17 new species Author Wells, Alice text Memoirs of Museum Victoria 2004 2004-12-31 61 1 85 110 https://museumsvictoria.com.au/collections-research/journals/memoirs-of-museum-victoria/volume-61-issue-1-2004/pages-85-110/ journal article 10.24199/j.mmv.2004.61.7 1447-2554 12209435 Oecetis brevidentata sp. nov. Figures 15–18, 106 Oecetis sp. E . — Wells, 1991 : figs 138, 172–176. Material examined. Holotype , male, NT, Katherine River Gorge National Park , 13°23.9’S 133°10.0’E , 13 Aug 1979 , J. Blyth ( NMV T-18524). Paratypes . NT: 4 males , 3 females , same data as for holotype ( NMV ) ; 1 male , Kakadu National Park , Jim Jim Creek , 3 km below falls, 13°15.9'S 132°51.1'E , 1 Sep 1979 , J. Blyth ( NMV ) ; 1 male , ARRS, South Alligator River , at Gimbat OSS Station , 13°34.3'S 132°36.7'E , 24 May 1988 , A. Wells and P. Suter ( NMV ) ; 9 males , 1 female , South Alligator River below BHP camp, 25 May 1988 , P. Suter and A. Wells ( NMV ) ; 2 males , ARRS, SAR site 1, 14 Jun 1988 , P. Dostine ( NTM ) ; 1 male , 1 female , ARRS, South Alligator River , at Gimbat OSS Station , 13°34.3'S 132°36.7'E , 28 Apr 1989 , P. Dostine ( NTM ) ; 2 males , 1 female , 12°48'S 132°49'E , Kakadu National Park , Baroalba Springs , 4 Oct 1991 , A. Wells ( NTM ) . Other material. NT: male, 3 females , ARRS South Alligator River above Fisher Creek jcn, 13°34'S 132°34'E , 18–20 Apr 1989 , Suter and Wells ( NTM ); 2 males , female, Gunlom (as UDP Falls), 13°24.9'S 132°26.0'E , 18–19 Jul 1980 , M.B. Malipatil ( NTM ) . Diagnosis. Forewing with length about 5 times maximum width, lamina marked by a distinctive cross formed by dark membrane and setae on t1 and t2 and their junction with R3–4; t1 and t2 contiguous, t3 well proximal of both. In male g enitalia, inferior appendages in ventral view slender and curving, and in lateral view with apices acute and directed ventrally, rather than straight as in O. multipunctata . Description . Tibial spurs 1, 2, 2. Male forewing length 6.1–7.8 mm . Wings with vestiture of even length, without spots, but forewing (Fig. 15) with distinctive dark cross marking the junctions of t1 and t2 with R, footstalk on fork 1 longer than fork. Male genitalia as in Figs 16–18. Segment IX widest midlaterally; preanal appendages separate, ovoid. Segment X elongate, membranous, dorsal process short, slender. Inferior appendages narrow, tapered, slightly bowed, apices down-turned in lateral view. Phallus with length about twice width, beak-like apically. Distribution . Alligator Rivers region of northern NT (Fig. 106). Remarks . The larva of this species is unique among Australian Oecetis species. Associated as ‘sp. E’ by Wells (1991) , it is the only Oecetis species of which I am aware that has short, blunt mandibles. This feature suggests that O. brevidentata has dietary habits quite different from other congeners. It may well be a detritivore. Etymology . Latin, descriptive of the larval mandibles.