Stetholus metatibialis, 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

publication ID	https://dx.doi.org/10.3897/zookeys.1073.71843
publication LSID	lsid:zoobank.org:pub:18D5AF27-86E5-4D21-BCC5-27D09FB384DA
persistent identifier	https://treatment.plazi.org/id/37506188-9496-40B4-BC38-10BE15FF63D3
taxon LSID	lsid:zoobank.org:act:37506188-9496-40B4-BC38-10BE15FF63D3
treatment provided by	ZooKeys by Pensoft
scientific name	Stetholus metatibialis
status	sp. nov.

Treatment

Stetholus metatibialis sp. nov.

Figs 11 View Figures 1–12 , 40 View Figure 40

Type locality.

Mt. Bellenden Ker northwest of Babinda; 17.2672° S, 145.8700° E; Wooroonooran National Park, north Queensland, Australia.

Type material.

Holotype female. "Bellenden Ker Range, NQ / Cable Tower 3 [now Tower 6], 1054m / 17 Oct.-5 Nov. 1981 / EARTHWATCH/QLD. MUSEUM // A.N.I.C. / COLEOPTERA / Voucher No. / 83-0611" [green label] // "HOLOTYPE / Stetholus / Stetholus metatibialis / Barr & Shepard" [red label, handwritten]. Dry pinned. Deposited in the Queensland Museum, South Brisbane; Registration Number QM T250615.

Differential diagnosis.

The single female specimen of S. metatibialis (Fig. 40 View Figure 40 ) is characterized by an elongate-oval body shape; labrum “moustache” composed of two discrete, lateral tufts of very long, dark, curved setae (setal origin unclear, possibly mandibular) (Fig. 40C View Figure 40 ); long pronotal basal sublateral carinae; and posterior surfaces of both the meso- and metatibiae glabrous and shiny. While other species of Stetholus may have similar labral tufts, none are as long and distinctive. The metatibia of S. elongatus (Fig. 36 View Figures 36, 37 ) has a narrow, elongate, posterior bare area of variable length, usually at the basal 1/3, as opposed to that of S. metatibialis in which the posterior surface is entirely bare; the metatibiae of the others are entirely setose. Stetholus elongatus and S. longipennis (Fig. 38 View Figures 38, 39 ) lack pronotal sublateral carinae. Stetholus metatibialis (Fig. 40 View Figure 40 ) bears a superficial resemblance to Ovolara species (Figs 23 View Figures 23, 24 - 26 View Figures 25, 26 , 28 View Figures 28, 29 - 31 View Figures 30, 31 ) because of its elongate-oval body and strongly punctate elytra, however it is easily separated by the very short prosternum anterior to the procoxae (vs. prosternum long, extended anteriorly) and the presence of a transverse pronotal impression (vs. no impression).

Description

(n = 1). Holotype female. Body: Size 3.9 mm long, 1.4 mm wide; elongate-oval. Dorsal color dark brown; head black; venter mostly brown; first two antennomeres, posterior metaventrite, coxae, trochanters, femora, posterior face of meso- and metatibiae yellow-brown. Setae of dorsal surfaces short, yellow, semi-erect and recumbent, setae of ventral surfaces long and recumbent. Head: Densely setose and punctate, punctures <1 diameter apart or nearly contiguous. Vertex with a faint V-shaped impression, open anteriorly, extending from antennal bases towards occiput; frontoclypeal suture straight, obscure. Antenna with 11 tomentose antennomeres; antennomeres 1 and 2 yellow-brown with coarse, yellow setae; antennomere 1 longest, ~ 3 × longer than wide, curved; antennomere 2 ovoid; antennomeres 3-11 brown with dense yellow setae, together forming a tight, elongate club; antennomeres 7-11 of equal width, antennomere 11 longer than all but antennomeres 1 and 2, apex bluntly rounded. Eye finely faceted, suboval at base, weakly protuberant; dorsal margin with fringe of long, curved setae. Clypeus transverse, convex, anterior margin straight; disc densely setose, lateral margins with longer setae. Labrum trapezoidal, wider than long, 2 × longer and slightly narrower than clypeus; densely setose; anterior margin weakly emarginate with band of short, yellow setae; lateral margins with dense fringes of long, yellow setae, each margin with a discrete tuft of very long, dark, curved setae extending to maxilla (setal origin unclear, possibly mandibular). Maxillary palpus with four setose palpomeres; palpomere 1 yellow, short, annular; palpomere 2 yellow, 2 × as long as wide; palpomere 3 yellow, nearly as long as 2, wider apically; palpomere 4 brown, longest and widest, ovoid, ventral surface with a broadly oval, slightly concave, pale sensory area angled obliquely from the apex to the base. Labial palpus yellow, glabrous, with three palpomeres; palpomeres 1 and 2 yellow, annular, short and narrow; palpomere 3 brown, conical, much longer and wider than others, apex truncate with a narrowly oval, flat, slightly concave, pale sensory area. P ronotum: Shape generally trapezoidal, slightly wider than long, widest at base; 1.0 mm long, 1.1 mm wide; disc densely punctate, punctures evenly spaced ~ 1 diameter apart. Anterior margin arcuate; anterior angles obsolete; lateral margins sinuate and arcuate, moderately explanate; posterior angles raised, protruding, acute, posterior margin weakly trisinuate. Disc weakly convex, more convex at basal 1/2; distinct, transverse V-shaped impression at apical 1/3-1/2; two distinct, basal, sublateral carinae 1/3-1/2 as long as pronotum, bordered by shallow medial impressions and lateral excavations; two shallow, indistinct prescutellar foveae. Scutellar shield: Cordate, longer than wide, apex rounded; flat; densely setose. Elytron: 2.9 mm long, 0.7 mm wide. Elytra conjointly 2 × as long as wide; anterior 2/3 almost parallel-sided; margins narrowly marginate. Humerus inflated, elytral base depressed medially; disc convex at anterior 1/3, flattened at 1/3-1/2 distance from base, then weakly convex to apex. Disc with ten strongly punctate, weakly impressed striae, intervals slightly raised, sutural interval more so; accessory basal stria of 6 punctures between striae 1 and 2 short; striae 3 and 4 join near apex; disc punctures large and deep at basal 2/3, becoming much smaller and shallower towards apex, separated by one diameter. Prosternum: Very short anterior to procoxae, marginate anteriorly. Prosternal process moderately narrow, long, 4 × longer than wide; nearly parallel-sided between coxae then slightly widened towards rounded apex; laterally marginate, medially sulcate at basal 1/2, carinate at apical 1/2; surface tomentose. Mesoventrite: Short, marginate, densely setose, with a deep mesoventral cavity to receive prosternal process. Metaventrite: Broadly rectangular; very setose; anterior margin marginate, bordered posteriorly by a small, transverse excavation; disc with discrimen extending almost from anterior to posterior margin, deeply incised at posterior 2/3; disc laterad to discrimen very convex; metakatepisternal suture distinct. Disc laterally with large, variably spaced punctures; punctures obscured medially by a broad, triangular patch of very long, dense, recumbent, yellow-orange setae. Legs: Of similar lengths; each leg with femur and tibia nearly subequal in length; foreleg stouter than the others; tarsus with tarsomere 5 longer than tarsomeres 1-4 combined, distinctly expanded at 1/3 distance to apex; claws simple, large, sharply acute. Pro- and mesocoxae yellow; metacoxae yellow medially, brown laterally, deeply sulcate; femora yellow, dorsal surfaces of each with a narrow brown stripe, apices brown; tibiae brown, meso- and metatibiae with posterior surfaces yellow-brown, glabrous, shiny; tarsi brown. Abdomen: Five ventrites; ventrites 2 and 3 subequal in length, ventrite 4 shortest, ventrite 5 longest; ventrites convex; ventrite 1 with a wide, triangular, intercoxal projection; ventrites 2-4 with lateral margins each produced to form a small, rounded lobe which clasps the epipleuron; ventrites 3 and 4 depressed basally, raised at posterior margins; ventrite 5 with impressions at basomedial and basolateral margins, apex rounded. Ventrites covered with shallow punctures variably spaced one or more diameters apart; punctures of ventrites 3-5 medially obscured by dense covering of yellow setae.

Etymology.

The specific epithet metatibialis is an adjective in the nominative singular derived from the Greek meta meaning after or posterior, and the Latin tibia, the lower portion of a leg. Metatibialis points to the diagnostic character present on the hind tibia, specifically, the glabrous posterior surface (Figs 40D View Figure 40 ).

Distribution.

North Queensland, Australia. Known only from the type locality in the Bellenden Ker Range in Wooroonooran National Park, west of Bellenden Ker and northwest of Babinda (Fig. 11 View Figures 1–12 ).

Habitat.

The single specimen was taken at UV light trap at an elevation of 1054 m on the east slope of Mt. Bellenden Ker. According to the project leader "the whole place is solid rainforest and there are many endemics at higher elevations" (G. Monteith, in litt.).