Potamophilinus papuanus Sato , 1973

Barr, Cheryl B. & Shepard, William D., 2021, A review of the Larainae of Australia with description of seven new species and the new genus Australara (Coleoptera, Byrrhoidea, Elmidae), ZooKeys 1073, pp. 55-117 : 55

Potamophilinus papuanus Sato, 1973

Figs 7 , 32 , 33

Type locality.

Wum, Upper Jimi Valley, NE New Guinea (Papua New Guinea) (holotype deposited in the Bishop Museum, Honolulu, Hawaii). Geographic coordinates unavailable.

Paratypes examined (2). NEW GUINEA (NE) / Wum, Upper Jimmi [Jimi] V. / 840 m. VII-17-'55 // J.L. Gressitt / Collector // Paratype / Potamophilinus / Potamophilinus papuanus M. Sato / DET. M. SATO 1972 (1 EMEC); NEW GUINEA (NE) / Wau, Morobe Distr. / 1200 m, 25-30.IV.62 // Light Trap / J. Sedlacek / BISHOP // Paratype / Potamophilinus / Potamophilinus papuanus M. Sato / DET. M. SATO 1972 (1 EMEC).

Other material examined (13). AUSTRALIA: no. QLD / Freshwater, Freshwater / Cr. at Ryan Weare Park / 16°53 ’13” S, 145°42 ’05” E / 18-I-2001, coll. C.B. Barr (2 EMEC); AUSTRALIA: Queensland / Freshwater / 18 I 2001 / Freshwater Creek / S 16°53'13" E 145°42'05" (WDS-A-1370 on reverse) // William D. / Shepard, leg. // Potamophilinus / Potamophilinus papuanus / W. D. Shepard (1 ANIC, 4 EMEC); AUSTRALIA: Queensland / Emerald Creek Store / 17 I 2001 / Emerald Creek / S 16°59'12" E 145°28'21" (WDS-A-1369 on reverse) // William D. / Shepard, leg // Potamophilinus / Potamophilinus papuanus / W. D. Shepard (2 EMEC); Upper Daintree R. / Via Daintree, / 27.xii.1964. N.Qld. / G. Monteith // EX UQIC / DONATED / 2011 (1 QM); W. Claudie River / Iron Range, NQ / 13 May 1971 / J.G.Brooks (3 ANIC).

Differential diagnosis

(n = 15). Body (Fig. 32 ) elongate, sides subparallel; antennae loosely clavate, not reaching to middle of pronotum; maxillary palpi each with tip of palpomere 4 obliquely truncate, elliptical; labial palpi with tip of palpomere 3 truncate, oval; pronotum flat, with a wide, U-shaped, transverse impression at anterior 1/3, without basal sublateral carinae; pronotal anterior angles depressed, posterior angles blunt, each with a large, adjacent oval depression; elytra striate-punctate, apices angulate; pro- and mesofemora broad and anteriorly flattened to slightly concave; prosternal process very long, carinate, broad between procoxae, abruptly narrowed and spinose between mesocoxae, apex acuminate; apices of metatibiae exceeding apices of elytra; abdomen with six visible ventrites, loosely fitted to epipleura; aedeagus (Fig. 33 ) very long and slender; penis and parameres abruptly angled at base; parameres fused with penis basally and appressed apically. Potamophilinus papuanus (Fig. 32 ) is easily differentiated from all other Australian laraines by characteristics of the pronotum, elytral apices, prosternal process, and unusual male genitalia (Fig. 33 ).

Variation.

Measured specimens from Australia vary in size from 4.4-4.9 mm long and 1.7-2.1 mm wide (n = 11). The females are larger than the males, but the sample size is small: females 4.6-4.9 mm long, 1.8-2.1 mm wide (n = 6); males 4.4-4.7 mm long, 1.7-1.9 mm wide (n = 5). In the species description, Satô (1973) reported a much wider size range in Papua New Guinea specimens: 4.2-5.6 mm long, 1.6-2.1 mm wide. In measurements of two specimens from the type series, the male is a full millimeter shorter than the female. The species is sexually dimorphic with males having the elytral apices truncate and angulate, and females having the elytral apices broadly rounded except for each with a deflexed, triangular tooth near the inner margin (visible in posterior view).

Distribution.

Potamophilinus papuanus occurs in Papua New Guinea, north Queensland (Fig. 7 ) and possibly the Northern Territory ( Glaister 1992, 1999), Australia.

Habitat and life history.

Our few records of P. papuanus are from large, sand-bottomed creeks with warm, clear water where specimens were collected from logs and branches in fast current. In the NT, Potamophilinus larvae occur among matted roots at margins of sandy streams (A.Glaister, in litt.). Three adult females, all collected in January, were dissected in the lab and had eggs in their abdomens: two had four eggs each and one had> 20 eggs. Therefore, January is within the reproductive period of the species. One of the specimens examined from New Guinea was collected in a light trap, as was the QM specimen although not labeled as such (G. Monteith, in litt.).

Associated byrrhoid taxa.

Elmidae : Larainae : Ovolara lawrencei sp. nov., O. leai , O. monteithi sp. nov., Stetholus longipennis sp. nov.; Elminae : Austrolimnius spp., Graphelmis pallidipes , Notriolus taylori , Notriolus spp., Simsonia spp.

Comments.

Potamophilinus papuanus was described from Papua New Guinea, and its occurrence in Australia is not listed in the world elmid catalog by Jäch et al. (2016). In order to confirm the species identification we examined two paratypes of P. papuanus from New Guinea and compared Satô’s illustration of the male genitalia ( Satô 1973) with the genitalia of four Australian specimens from north Queensland.

Figures

Figures 1 - 12. Geographical distribution of species records 1 Australara glaisteri gen. nov., sp. nov. 2 Hydora laticeps 3 Ovolara australis 4 Ovolara lawrencei sp. nov. 5 Ovolara leai 6 Ovolara monteithi sp. nov. 7 Potamophilinus papuanus 8 Stetholus carinatus sp. nov. 9 Stetholus elongatus 10 Stetholus longipennis sp. nov. 11 Stetholus metatibialis sp. nov. 12 Stetholus woronora sp. nov.

Figures 32, 33. Potamophilinus papuanus, male 32 habitus, 4.6 mm long A dorsal B ventral 33 male genitalia A dorsal view B lateral view C ventral view.