Oecetis pechana Mosely, 1953

Wells, Alice, 2006, A review of Australian long-horned caddisflies in the Oecetis pechana-group (Trichoptera: Leptoceridae), with descriptions of thirteen new species, Memoirs of Museum Victoria 63 (2), pp. 107-128 : 110

Oecetis pechana Mosely

Figures 1–6, 56

Oecetis pechana Mosely in Mosely and Kimmins, 1953: 302, figs 213–215. — Neboiss, 1977: 143, figs 764–769. — Neboiss, 1986: 267.

Material examined. Holotype. Male, Yanchep, WA, 31°32.9'S, 115°41.2'E ( BMNH).

Other material: Some 240 samples from all states of Australia were examined, in collections of NMV, ANIC, QM, NTM.

Diagnosis. Male. Recognised by a combination of wing features, including scale patches, and the general form of the genitalia with inferior appendages in ventral view stoutly clasper-shaped, smoothly curved mesially, and broadly rounded apically; abdominal segment X a simple membranous plate; the phallus long and straight, extending the length of 3–4 abdominal segments, and having the paramere stout and darkly sclerotised. Male forewing (fig. 1) length 5.5–9.6 mm.

Males of closely similar species differ from O. pechana as follows: O. walpolica has the inferior appendages in lateral view tapered to narrowly rounded apex, phallus shorter, its length equalling about 2 abdominal segments, and the paramere strongly arched dorsally; O. katae has inferior appendages in lateral view even more narrowly tapered and curved upwards, phallus shorter, paramere arched ventrally; O. magelensis has the inferior appendages shallowly excavated mesially, phallus shorter, about 2–3 abdominal segments in length; O. gilva usually has no scales on the forewing, inferior appendages in lateral view attenuate apically, and phallus very short, about length of 1.5 abdominal segments, without paramere.

Distribution. Australia-wide.

Remarks. As defined here, O. pechana is difficult to distinguish from closely similar species, since the key diagnostic feature is the length of the male phallus. This feature is surely biologically significant, acting as a reproductive isolating mechanism, determining mating success. Nevertheless, it does appear likely that hybridisation between O. pechana and other species occurs, and this may be confirmed if molecular studies are carried out in the future. Oecetis suteri similarly has the phallus elongate, but can easily be distinguished by the much reduced inferior appendages. Oecetis pechana is often common in both lentic and lotic systems, where its larvae build tube cases of sand.