Stetholus Carter & Zeck, 1929

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

Genus Stetholus Carter & Zeck, 1929

Type species.

Stetholus elongatus Carter & Zeck, 1929.

Diagnosis.

Body elongate, sides subparallel; antennae clavate, either compact or elongate, reaching at least to middle of pronotum; labrum with lateral brushes of long, curved setae; maxillary palpi long, prominent, enlarged apically, each with nearly half of palpomere 4 composed of a ventral, widely open, white sensory area obliquely angled from the apex to the base; pronotum with or without basal sublateral carinae; pronotal disc with a shallow to moderately deep, transverse, broadly V-shaped impression generally at anterior 1/3-1/2; elytra striate-punctate, laterally compressed at basal 1/2, apices rounded; prosternum very short anterior to procoxae; prosternal process moderately narrow, with a median longitudinal carina; apices of hind tibiae not exceeding apices of elytra; abdominal ventrites 1-2 combined shorter than 3-5 combined (Figs 34 - 42 ).

Distribution.

Stetholus is endemic to Australia, with species occurring in Queensland, the Australian Capital Territory, New South Wales and Victoria (Figs 8-12 ). There was a record in the Atlas of Living Australia (ALA) https://www.ala.org.au/ database of a specimen from Tasmania, but the specimen was misidentified therefore the record was erroneous (S. Grove, in litt.). It has since been deleted.

Habitat and behavior.

Adults are usually found in fast or turbulent water in rocky chutes, below waterfalls and spillways, on log jams and boulders in rapids, and among root masses in the current, often in large aggregations. They fly readily when disturbed. Specimens also have been collected with light traps and flight intercept traps (A.Glaister, in litt.; G. Monteith, in litt.).

Comments.

Three of the five known species exhibit secondary sexual dimorphism with the females having the posterior 1/4 of the elytron slightly explanate lateral to stria 11. This is most pronounced in S. longipennis sp. nov., but is less so and somewhat variable in S. elongatus and S. woronora sp. nov. The larva of Stetholus was keyed and illustrated by Glaister (1999).

Figures

Figures 34, 35. Stetholus carinatus sp. nov., holotype male 34 habitus, 3.7 mm long A dorsal B ventral 35 male genitalia A dorsal view B lateral view C ventral view.

Figures 41, 42. Stetholus woronora sp. nov., holotype male 41 habitus, 5.2 mm long A dorsal B ventral 42 male genitalia A dorsal view B lateral view C ventral view.

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.