Stetholus woronora, Barr & Shepard, 2021

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

Stetholus woronora sp. nov.

Figs 12 , 41-42 , 43

Type locality.

Woronora River north of Engadine; 34.0465° S, 151.0062° E; New South Wales, Australia (Fig. 43 ).

Type material.

Holotype male. "AUSTRALIA: NSW / Woronora River, N / Engadine, S Sydney / -34.04652, 151.00621 / 10 m, 23.xi.2019 // Fikáček, Seidel / & Sýkora lgt. / AU-2019-34 // HOLOTYPE / Stetholus / Stetholus woronora / Barr & Shepard" [red label, handwritten]. Dry pinned. Deposited in the Australian National Insect Collection, Canberra; ANIC Database Number 25-077643. Paratypes (9). Same data as for holotype (4 ANIC, 3 EMEC, 2 NMPC). Paratypes all with the following label: PARATYPE / Stetholus / Stetholus woronora / Barr & Shepard [yellow label, printed].

Differential diagnosis.

Stetholus woronora (Figs 41 , 42 ) can be distinguished from other species of Stetholus (Figs 34 - 40 ) by a combination of the following characters: Body large,> 5.0 mm long; antennae clavate; pronotum with very short, basal sublateral carinae; male genitalia stout and heavily sclerotized. Stetholus elongatus (Fig. 36 ) most closely resembles S. woronora but lacks pronotal carinae; the male genitalia are somewhat similar but the penis of S. elongatus (Fig. 37 ) is narrow and tapered at the apex whereas that of S. woronora (Fig. 42 ) is wide and bulbous. The other three species of Stetholus are much shorter (4.5 mm or less) and do not have similarly stout, heavily sclerotized genitalia (those of S. metatibialis are unknown). Furthermore, S. longipennis (Fig. 38 ) lacks sublateral pronotal carinae; S. metatibialis (Fig. 40 ) and S. carinatus (Fig. 34 ) both have much longer, more prominent carinae.

Description

(n = 10). Body: Size 5.2-5.6 mm long, 1.9-2.2 mm wide (n = 9). Color black except first two antennomeres, trochanters and basal 2/3 of femora yellow-brown or light red-brown. All surfaces covered with short pale yellow or longer black setae. Head: Heavily punctate and setose, with many long, erect and semierect, curved, black setae and much shorter pale yellow setae. Eye finely faceted, suboval at base, weakly protuberant; with a dorsal and posteroventral fringe of long, curved, black setae. Antenna with eleven antennomeres; antennomere 1 3 × longer than wide, curved; antennomere 2 spherical; both with long, curved, black setae; antennomeres 3-11 forming an elongate club. Frons with a distinct Y-shaped impression, upper arms nearly reaching antennal bases, frons depressed between; frontoclypeal suture straight. Clypeus broadly rectangular, emarginate anteriorly, convex, densely setose. Labrum narrower than clypeus, trapezoidal, widest at base, weakly emarginate; anterior margin with band of short, pale yellow setae, lateral margins with long, dense brushes of light and dark, curved setae. Maxillary palpus black, setose, with four palpomeres; palpomere 1 short; palpomeres 2 and 3 longer; palpomere 4 longer and wider, ventral surface with a circular to oval, concave, white sensory area angled obliquely from the apex to the base. Labial palpus black, glabrous, with three palpomeres; terminal palpomere quadrate, apex with oval white sensory area. Pronotum: Shape generally trapezoidal, slightly wider than long, widest at base; 1.1-1.3 mm long, 1.3-1.5 mm wide; disc heavily and evenly punctate and setose; punctures deep, spaced mostly 1 diameter apart; setae either short, fine, pale yellow or longer, stout, dark. Anterior margin arcuate; anterior angles obsolete; lateral margins weakly trisinuate; posterior angles 90°, depressed; posterior margin weakly trisinuate. Disc with a shallow, broadly V-shaped, transverse impression from anterior 1/3-1/2 contiguous with a short, median, longitudinal impression; two shallow, oblique, lateral impressions at posterior 1/3; two very short, basal, sublateral carinae; two deep prescutellar foveae. Scutellar shield: Subtriangular with margins weakly arcuate, apex acute, raised; velvety in appearance due to very dense, short, pale yellow setae unlike that of pronotum and elytra. Elytron: 4.0-4.4 mm long, 1.0-1.1 mm wide. Elytra conjointly 2 × as long as wide, slightly widened at apical 1/3; apices together evenly rounded with a small notch between. Setae short, fine, pale yellow. Humerus prominently swollen; anterior margin narrowly depressed inside of humerus, especially at base of interval 6; disc at 1/3 distance from base with a shallow depression from suture to stria 4. Disc with 10 punctate striae; punctures small and spaced <1 diameter apart, stronger anteriorly, fainter posteriorly; accessory basal stria between striae 1 and 2 long; stria 3 ending before posterior margin, striae 4 and 5 joining and ending just before posterior margin. Metathoracic wings: Macropterous. Prosternum: Very short anterior to procoxae, margined; prosternal process very setose, moderately narrow, 3 × longer than wide, with a distinct median longitudinal carina, apex rounded. Mesoventrite: Short, wide; disc concave between mesocoxae, with a deep mesoventral cavity to receive prosternal process; covered with short yellow setae. Metaventrite: Broadly rectangular; with a wide, circular, median depression covering posterior 3/4; discrimen as long as median depression; metakatepisternal suture present; disc heavily punctate, punctures small and often contiguous; disc covered with short, dense, yellow setae. Legs: Of different lengths, fore leg shortest, hind leg longest; each leg with femur shorter than tibia; mesotibia narrower than pro- and metatibia; tarsus with tarsomere 5 slightly longer than tarsomeres 1-4 combined; claws large, simple, acute. Coxae black, metacoxae deeply sulcate; femora yellow-brown or light red-brown each with dorsal surfaces and apical 1/3 black; tibiae black; mesotibiae with posterior surfaces flat, glabrous, shiny; metatibiae weakly arcuate; tarsi black. Abdomen: Five convex ventrites, each with a shallow depression near lateral margin; ventrite 1 with margined, broadly triangular, intercoxal projection; ventrites 2-4 widely rectangular, with lateral margins each produced to form a small lobe of varying size, those of ventrites 3 and 4 largest, which clasps the epipleuron; ventrite 5 with lateral margins evenly curved with broadly rounded apex. Ventrites covered with shallow, often contiguous, punctures, and semi-erect and recumbent yellow setae. Aedeagus: Mostly well-sclerotized; short, broad, widest at apex of phallobase; phallobase longer than parameres, parameres slightly shorter than penis; phallobase open dorsally (Fig. 42 ). In dorsal view (Fig. 42A ), parameres broad at base, abruptly digitate at apices; medial margin darkly sclerotized at basal 2/3 due to folding of the margin ventrally, inner surface flat against penis; medial margin weakly divergent at basal 1/2, arcuate and strongly divergent at apical 1/2, sinuate before apex; lateral margins evenly arcuate with four, small, sharp teeth near apex. Penis very broad, less well-sclerotized than parameres, medially inflated at basal 2/3 between parameres forming a longitudinal, margined, flat-topped carina; apex bell-shaped, tip produced and bent ventrally; no visible corona; basal apophyses moderately long, 1/2-2/3 as long as phallobase, straight, very broad, transversely truncate at tips. In lateral view (Fig. 42B ), aedeagus widest midway between apex and base; paramere broadly triangular in outline, moderately convex dorsally, moderately concave ventrally, apex acute; penis apex narrowly rounded, curved ventrally slightly above paramere apex. In ventral view (Fig. 42C ), parameres with arcuate median margins, thickened at basal 1/3; penis with tip longitudinally carinate, fibula absent. Ovipositor: Well-sclerotized; elongate, 2.5 × longer than wide; baculum 1/4 longer than gonocoxite; proximal gonocoxite subrectangular except widened medially at base, with two teeth; distal gonocoxite 2 × longer than proximal gonocoxite, base 2 × wider than apex, apex broader than middle, median margins straight, lateral margins sinuate; stylus narrow, 1/4-1/3 length of distal gonocoxite.

Variation.

Females exhibit minor secondary sexual dimorphism with the lateral margin of the elytra very slightly explanate at the posterior 1/4 laterad to stria 11; in males, stria 11 is just inside the lateral margin, which is not explanate. The specimens vary from 5.2-5.6 mm long and 1.9-2.2 mm wide (n = 9). Males are slightly larger than the females, but the sample size is small, particularly for females: males 5.3-5.6 mm long, 2.0-2.2 mm wide (n = 6); females 5.2-5.5 mm long, 1.9-2.1 mm wide (n = 3). Except for small differences in the depth and extent of the pronotal impressions, the specimens are otherwise quite uniform.

Etymology.

The specific epithet woronora, a noun in the genitive case, refers to the type locality of the species, the Woronora River (Fig. 43 ). Woronora is an Aboriginal place name meaning black rocks in the Dharug (or Darug) language.

Distribution.

New South Wales, Australia. Known only from the type locality south of Sydney (Fig. 12 ).

Habitat.

Although the Woronora River normally has pools interspersed with riffles at the type locality, collector Sýkora (in litt.) reported that due to a severe drought "the river there is pretty much just a small stream and we were surprised there was still some water, given the drought at that time." The specimens were obtained by "water collecting in a small rapids of a small stream in rocky pool" ( Sýkora, in litt.) at an elevation of 10 m (Fig. 43 ).

Associated byrrhoid taxa.

Elmidae : Elminae : Kingolus sp., Notriolus sp., Simsonia sp.

Figures

Figure 40. Stetholus metatibialis sp. nov., holotype female, 3.9 mm long A dorsal habitus B ventral habitus C head, frontal view D head, ventral view.

Figure 43. Stetholus woronora sp. nov., type locality: Woronora River, north of Engadine, NSW, Australia (photograph courtesy of Martin Fikacek, National Museum, Prague, Czech Republic).

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 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 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 36, 37. Stetholus elongatus 36 female habitus, 5.2 mm long A dorsal B ventral 37 male genitalia A dorsal view B lateral view C ventral view.

Figures 38, 39. Stetholus longipennis sp. nov., male 38 habitus, 4.2 mm long A dorsal B ventral 39 male genitalia A dorsal view B lateral view C ventral view.