Oecetis brevidentata, Wells, 2004

Wells, Alice, 2004, The long-horned caddisfly genus Oecetis (Trichoptera: Leptoceridae) in Australia: two new species groups and 17 new species, Memoirs of Museum Victoria 61 (1), pp. 85-110 : 91

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.