Stetholus longipennis, 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 longipennis sp. nov.

Figs 10 , 27 , 38 , 39

Type locality.

Hunters Creek north of Mount Molloy; 16.6324° S, 145. 3254° E; north Queensland, Australia.

Type material.

Holotype male. "AUSTRALIA: Queensland / 5 km N Mount Molloy / 17 I 2001 / Hunters Creek / S 16°38 ’00” E 145°19 ’27” (WDS-A-1368 on reverse) // William D. / Shepard, leg. // HOLOTYPE / Stetholus / Stetholus longipennis / Barr & Shepard" [red label, handwritten]. Dry pinned. Deposited in the Australian National Insect Collection, Canberra; ANIC Database Number 25-077642. Paratypes (108). Same data as for holotype (1>AM, 1 ANIC, 13 EMEC, 1 QM); AUSTRALIA: no. QLD / Hunters Creek at Hwy. 44 / 5 rd. km. N Mount Molloy / 16°38 ’00” S, 145°19 ’27” E / 17-I-2001, coll. C. B. Barr (5 EMEC, 1 QM); AUSTRALIA: no. QLD / Bushy Creek at Hwy. 44 / just W of Julatten / 16°36 ’40” S, 45°20 ’10” E / 17-I-2001, coll. C.B.Barr (1 EMEC); AUSTRALIA: no. QLD / Emerald Creek at Hwy. 1 / E of Mareeba / 16°59 ’12” S, 145°28 ’21” E / 17-I-2001, coll. C.B. Barr (6 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. (1>AM, 9 EMEC); 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 (6 EMEC); AUSTRALIA: Queensland / Freshwater / 18 I 2001 / Freshwater Creek (WDS-A-1370 on reverse) // William D. / Shepard, leg. (2 EMEC); AUSTRALIA: no. QLD / Mulgrave River at Hwy. 1 / 1 rd. km. S of Gordonvale / 17°06 ’10” S, 145°47 ’15” E / 18-I-2001, coll. C. B. Barr (5 EMEC, 1 QM); AUSTRALIA: Queensland / 1 km S Gordonvale, 18 I 2001 94 ft / Mulgrave River / (WDS-A-1371 on reverse) // William D. / Shepard, leg. (1>AM, 1 ANIC, 2 EMEC, 1 QM); AUSTRALIA: no. QLD / Fishery Creek at / Hwy. 1, Fishery Falls / 17°11 ’10” S, 145°53 ’11” E / 18-I-2001, C. B. Barr (6 EMEC); AUSTRALIA: Queensland / Fishery Falls / 18 I 2001 / Fishery Creek (WDS-A-1372 on reverse) // William D. / Shepard, leg. (1>AM, 1 ANIC, 2 EMEC); QLD. Babinda / Apr. 1946 / J.G.Brooks (3 ANIC); 16.03S to 16.05S / 145.28E Cape / Tribulation area / QLD 21-28Mar.1984 / A.Calder & T.Weir // on rocks / in stream (1 ANIC); 16.03S to 16.05S / 145.28E QLD, Cape / Tribulation area / 1-11 May 1992 / J.F.Lawrence // on rocks / in stream (1 ANIC); same data as for preceding // Genitalia prep. / HS-243 ♂ / A.Calder 1997 (1 ANIC); same data as for preceding // Genitalia prep. / HS-274 ♀ / A.Calder 1997 (1 ANIC); QLD. Cardstone / 23 Jan. 1965 / J.G.Brooks / at light (4 ANIC); same data as for preceding // Genitalia prep. / HS-307 ♀ / A.Calder 1999 (1 ANIC); Cardstone, N.Q. / 23.i.65. J.G. & / J.A.G.Brooks // Genitalia prep. / HS-241 ♂ / A.Calder 1997 (1 ANIC); Crystal Cascades / Via Cairns, N.Qld. / 22.xii.1964. / G. Monteith // EX UQIC / DONATED / 2011 (7 QM); same locality / H.A.Rose. (1 QM); Crystal Cascades / Cairns, N.Qld. / 30.xii.1963. / G. Monteith // EX UQIC / DONATED / 2011 (1 QM); QLD. Gordonvale / Apr. 1946 / J.G.Brooks // J. G. Brooks / Bequest, 1976 (4 ANIC); Little Mulgrave R. / Gordonvale, N.Q. / Apr. 1946 / J. G. Brooks // Australian Museum / K 579979 (2>AM); Mossman, Q. / 25 Mar 1967 / M.S. Upton (1 ANIC); Mossman Gorge / Via Mossman, N.Qld. / 25-26.xii.1964. / G. Monteith // EX UQIC / DONATED / 2011 (2 QM); Mt. Molloy, Q. / Station Creek, at light / 30.xii.69 J.G.Brooks (1 ANIC); 32km S [N?] of Ravenshoe, Q. / (17.38S, 145.29E) / K. Hyde // 12.ii.1966, Genitalia prep. / HS-239 ♂ / A.Calder 1997 (1 ANIC); same data as for preceding // Genitalia prep. / HS-240 ♂ / A.Calder 1997 (1 ANIC); Upper Daintree R. / Via Daintree, / 27.xii.1964. N.Qld. / G. Monteith // EX UQIC / DONATED / 2011 (3 QM); Upper Finch Hatton / Ck., Via Finch / Hatton, N.Qld. / 3.i.1965. / G. Monteith // EX UQIC / DONATED / 2011 (1 QM); Upper Mulgrave River, / 30.iv.1970, N.Qld. / G. B. Monteith // EX UQIC / DONATED / 2011 (2 QM). Paratypes all with the following label: PARATYPE / Stetholus / Stetholus longipennis / Barr & Shepard [yellow label, printed].

Other material examined

(17). Archers Ck., Q. / Mt. Garnet Rd. , / 28.xii.1964 / J.G.Brooks (1 ANIC); Bellenden Ker Range, NQ / Cableway Base Stn , 100m / 17 Oct.-9 Nov. 1981 / EARTHWATCH/QLD. MUSEUM / MV light, rainforest // A.N. I.C. / COLEOPTERA / Voucher No. / 83-0610 [green label] // Stetholus / sp. 1 / det. T. A. Weir 1983 (1 QM); Cardstone, N.Q. / 23.i.65. J.G. & / J.A.G.Brooks (4 ANIC); Cardstone QLD / 10-13.iii.1966 / K. Hyde (1 ANIC); Henrietta Ck., / Palmerston Nat. / Pk., N.Qld. / 29.xii.1964. / G. Monteith // EX UQIC / DONATED / 2011 (1 QM); Millstream at Archers / Ck. N. Q. Mt. Garnet / Rd. 28.xii.64 / J.G. Brooks (1 ANIC); same data as for preceding // Genitalia prep. / HS- 306 ♀ / A.Calder 1999 (1 ANIC); same data as for preceding // Genitalia prep. / HS- 308 ♀ / A.Calder 1999 (1 ANIC); Mossman Gorge / Via Mossman, N. Qld. / 25-26.xii.1964. / G. Monteith // EX UQIC / DONATED / 2011 (1 QM); 3 mls.W. of / Mossman, Q. / 14 Mar. 1964 / I.F.B.Common / & M.S.Upton (1 ANIC); 32km S [N?] of Ravenshoe, Q. / (17.38S, 145.29E) / K. Hyde // 16.ii.1966 (3 ANIC); Spring Ck. N. Q. / Heberton Rd. / 30.xii.64 / J.G. Brooks (1 ANIC) .

Differential diagnosis.

Stetholus longipennis (Fig. 38 , 39 ) can be distinguished from other species of Stetholus (Figs 34 - 37 , 40 - 42 ) by a combination of the following characters: Length usually shorter than or equal to 4.6 mm; antennae slender, almost moniliform; pronotum smooth or lightly sculptured, sublateral carinae absent; metatibiae entirely setose; male genitalia with penis very slender and much longer than parameres. Conversely, S. metatibialis (Fig. 40 ) and S. carinatus (Fig. 34 ) both have long, distinct sublateral pronotal carinae; S. woronora (Fig. 41 ) has very short carinae; and all three have distinctly clavate antennae. Stetholus elongatus (Fig. 36 ) also lacks pronotal carinae, but is usually longer than 4.6 mm and the antennae are clavate. The male genitalia of S. longipennis (Fig. 39 ) are strikingly different from those of other Stetholus (Figs 35 , 37 , 42 ) excluding S. metatibialis for which males are currently unknown.

Description

(n = 127). Body: Size 4.1-4.6 long, 1.6-1.8 wide (n = 21). Color dark brown to black dorsally and ventrally, but appearing lighter due to layer of dense, short, yellow setae; first two antennomeres, trochanters, basal 2/3-3/4 of femora yellow; apical antennomeres, coxae, tibiae, tarsi dark brown. Head: Punctures shallow, fine, evenly spaced; setae fine, yellow, recumbent to erect. Vertex with faint V- or U-shaped impression, open anteriorly, extending from near antennal bases to a distinct median impression; frontoclypeal suture arcuate. Antenna with eleven antennomeres; antennomere 1 longest, 3 × longer than wide, curved; antennomere 2 spherical; both with long, curved setae; antennomere 3 ovoid; antennomeres 4-11 each subspherical, widening slightly towards antennal apex, forming a slender, elongate, almost moniliform, club. Eye finely-faceted, suboval at base, moderately protuberant; dorsal and posteroventral margin with fringe of long, curved, black setae. Clypeus convex, broadly rectangular, emarginate anteriorly, densely setose. Labrum rectangular, longer and slightly narrower than clypeus; setose; anterior margin weakly emarginate, with band of short, yellow setae; lateral margins each with a wide, dense band of long, curved setae. Mandible with two teeth, outermost acute apically, innermost truncate apically; prostheca shelf-like, very thin, apically with coarse, long setae; molar area large, moderately oval, surface striate; lateral edge basally with a partially free lobe with several thin setae. Maxillary palpus black, setose, with four palpomeres; palpomere 1 short, annular, with inner apical border spine-like; palpomere 2 twice as long as wide; palpomere 3 as long as 2, wider apically; palpomere 4 wide, ventral surface with a subcircular, concave, white sensory area angled obliquely from the apex to the base. Labial palpus black, glabrous, with three palpomeres; palpomeres 1 and 2 short, annular; palpomere 3 longer, wider, quadrate, apex truncate with an oval, concave, white sensory area. Pronotum: Shape generally trapezoidal, wider than long, widest at base; length 0.8-1.0 mm, width 1.2-1.3 mm; disc with distinct punctures evenly spaced ~ 1 diameter apart, deeper near lateral margins; densely setose, with short, fine, yellow setae and longer, coarser, dark setae. Anterior margin arcuate; anterior angles obsolete; lateral margins bisinuate; posterior angles 90°, blunt, depressed; posterior margin weakly trisinuate. Disc slightly convex; shallow, broadly V-shaped, transverse impression at apical 1/4-1/2; basal 1/2 with two faint to distinct, oblique, lateral depressions and two large, deep prescutellar foveae; pronotal margin inflated posterior to fovea. Scutellar shield: Cordate; posterior apex slightly raised; finely setose. Elytron: 3.3-3.6 mm long, 0.8-0.9 mm wide. Elytra conjointly ~ 2 × as long as wide, widest near posterior 1/3; apices together forming a triangular notch between. Humerus prominently inflated, elytral base depressed medially; disc at 1/4-1/3 distance from base with a shallow depression from suture to stria 5. Disc with 10 punctate, weakly impressed striae, intervals flat; punctures very fine, spaced one diameter apart, obsolete apically; accessory basal stria between striae 1 and 2 long; stria 3 ending before apex; striae 4 and 5 joining before apex; striae 10 and 11 joining and ending before apex. Metathoracic wings: Macropterous. Prosternum: Very short anterior to procoxae; prosternal process moderately narrow, 3 × longer than wide, margined, with a median longitudinal carina, apex narrowly rounded. Mesoventrite: Short; disc convex between mesocoxae with a deep mesoventral cavity to receive prosternal process. Metaventrite: Broadly rectangular; disc with a median, round concavity near anterior margin and a wide median depression covering posterior 1/2-2/3; discrimen extending from concavity to posterior margin; metakatepisternal suture distinct; disc with small, shallow, variably spaced punctures mostly obscured by dense, fine, recumbent, yellow setae. Legs: Of similar lengths; each leg with femur and tibia subequal in length; tarsus slender, with tarsomere 5 slightly longer than tarsomeres 1-4 combined; claws simple, moderately large, sharply acute. Coxae dark brown, metacoxae deeply sulcate; femora yellow, dorsal surfaces of each with a narrow brown stripe, apical 1/4-1/3 dark brown; tibiae dark brown, mesotibiae with posterior surfaces nearly glabrous, shiny; metatibiae entirely setose, weakly arcuate. Abdomen: Five convex ventrites, each with a shallow depression near lateral margin; ventrite 1 with a margined, broadly triangular, intercoxal projection; ventrites 2-4 broadly rectangular, with lateral margins each produced to form a small lobe of varying size, largest on ventrites 3 and 4, which clasps the epipleuron; posterior border of ventrite 5 with a broadly rounded apex. Ventrites covered with shallow punctures spaced 1-2 diameters apart, mostly obscured by dense covering of yellow setae; setae longer at median 1/5 of ventrites 3-5. Aedeagus: Phallobase lightly sclerotized, open dorsally, fused to short parameres; penis very long, nearly as long as phallobase and parameres together (Fig. 39 ). In dorsal view (Fig. 39A ), parameres with lateral margins sinuate, convergent from junction with phallobase to near apex then strongly divergent and curved laterally; median margins nearly parallel at basal 2/3 then strongly divergent; apices acute. Penis beyond paramere tips with lateral margins nearly parallel almost to acute apex; no visible corona; dorsal median longitudinal carina with darker sclerotization present; basal apophyses very long, nearly as long as phallobase, straight, very broad, blunt at tips. In lateral view (Fig. 39B ), paramere triangular, moderately convex dorsally, nearly flat ventrally; apex broadly rounded to truncate with a few, small, irregular teeth; penis curved, tip ventrally directed. Fibula absent. Ovipositor: Moderately sclerotized; oval in outline, 2 × longer than wide; baculum ~ 2 × longer than gonocoxite; proximal gonocoxite subrectangular, wide and short; distal gonocoxite narrow and short, ~ 2 × as long as wide, length equal to proximal gonocoxite length, median and lateral margins arcuate, together separate basally but contiguous medially to apices; stylus very narrow.

Variation.

The females exhibit minor secondary sexual dimorphism with the lateral elytral margin slightly explanate at the posterior 1/4 laterad of stria 11; in males, stria 11 is just inside the lateral margin, which is not explanate. Measured specimens vary from 4.1-4.6 long and 1.6-1.8 wide (n = 21). The females are slightly larger than the males: females 4.3-4.6 mm long, 1.8 mm wide (n = 8); males 4.1-4.5 mm long, 1.6-1.8 mm wide (n = 13). The width of the prosternal process varies a bit between individuals. Otherwise, except for minor differences in the depth and extent of pronotal impressions, the specimens are quite uniform.

Etymology.

The specific epithet longipennis, an adjective in the nominative singular derived from the Latin longi (long) plus pennis (penis), refers to the male genitalia in which the length of the penis greatly exceeds the length of the parameres (Fig. 39 ).

Distribution.

Stetholus longipennis occurs in north and central Queensland, Australia (Fig. 10 ).

Habitat and behavior.

Stetholus longipennis was collected by the authors from medium to large sand-bottomed streams with logs and debris, some with boulders, and a small river at elevations ranging from 5-417 m (Fig. 27 ). All had clear water which varied from warm to cool. The beetles were collected from logs and rocks in fast current or rapids, and from a spillway. The adults fly readily from the net, and also have been taken at lights. At the type locality, Hunters Creek, the stream was well-shaded, with many logs and much debris, and many S. longipennis were concentrated on a concrete spillway below a bridge.

Associated byrrhoid taxa.

Elmidae : Larainae : Australara glaisteri sp. nov., Ovolara lawrencei sp. nov., O. leai , O. monteithi sp. nov., Potamophilinus papuanus ; Elminae : Austrolimnius spp., Graphelmis pallidipes , Kingolus spp., Notriolus taylori , Notriolus spp., Simsonia sp. Psephenidae : Sclerocyphon basicollis , Sclerocyphon minimus .

Figures

Figure 27. Ovolara lawrencei sp. nov., type locality, and Stetholus longipennis sp. nov., collection locality: Emerald Creek, east of Mareeba, QLD, Australia (photograph courtesy of David Rentz, James Cook University, Smithfield, QLD).

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.

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 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.

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 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.