Leielmis hirsutus, Bilton, David T., 2017

Bilton, David T., 2017, A revision of the South African riffle beetle genus Leielmis Delève, 1964 (Coleoptera: Elmidae), Zootaxa 4254 (2), pp. 255-268 : 266-268

Leielmis hirsutus sp. nov.

( Figs 1–7 )

Type locality. South Africa, Western Cape, Groote Winterhoek mountains, small stream below Sneeugatpiek , 1,300 m ( Fig. 7 B).

Type material. Holotype (male): “ 11/ii/2015 South Africa WC// Groote-Winterhoekberge stream below// Sneeugatpiek 1,300 m D T Bilton leg.” (genitalia extracted and mounted in DMHF on same card) and red holotype label “ Leielmis hirsutus // Holotype // D T Bilton 2017” ( ISAM) .

Paratypes (29) 12 ♂ 17 ♀ same data as holotype ( AMG, BMNH, CDTB, NMW, SANC, TMSA) . All with red paratype labels “ Leielmis hirsutus // Paratype// D T Bilton 2017”.

Description. Size: Holotype: body length (front of pronotum to elytral apices) 2.0 mm; maximum width (elytra) 1.20 mm; elytral length 1.45 mm. Same values for paratypes: 2.0– 2.05 mm, 1.15–1.20 mm and 1.40–1.45 mm respectively.

Colour: Dorsum ( Fig. 1 C) dark brown with conspicuous golden setae; anterior margin of pronotum reddish. Legs dark reddish brown, tarsi paler, yellowish. Antennae with segments 1–4 pale straw yellow, 5–11 infuscated, especially segments 10–11. Maxillary palpi dark blackish brown; cardo and stipes yellow. Labial palpi straw yellow, apical segment infuscated. Venter dark brown to black; mentum reddish brown; ligula yellow.

Head: Triangular, narrowed to apex. Labrum triangular, with acuminately rounded apex; approximately 0.7x as wide as clypeus, 0.5x as long; shining, microreticulate and finely granulate and punctate, punctures bearing curved, recumbent setae. Clypeus also shining, strongly microreticulate and finely granulate and punctate, punctures bearing curved, recumbent setae; microreticulation meshes isodiametric anteriorly, transverse posteriorly. Frontoclypeal suture feebly impressed; weakly arcuate. Frons shining, with moderate, medium punctures, bearing curved, golden, recumbent setae; sparsely, coarsely granulate, without evident microreticulation. Eyes occupying approximately half side of head; rounded anteriorly, relatively flat laterally and posteriorly. Maxillary palpi with segment 3 flat and expanded laterally, broader and longer than segment 4. Labial palpi with segment 2 flat and expanded laterally, segment 3 narrower and shorter.

Pronotum: Transverse, 1.6x broader than long; broadest at posterior margin, narrowing strongly to front angles; posterior margin approximately 1.9x width of anterior. Arched, anterior margin broadly arcuate in middle, forming a hood which shields much of the head. Posterior margin bisinuate around centre. Lateral margins strongly bordered, weakly rounded. Anterior angles acute; posterior angles obtusely rounded. Surface ( Fig. 2 C, F) shining, without evident microreticulation; doubly punctate, with moderate, medium punctures, interspersed with moderate, fine punctures, larger punctures becoming larger towards posterior margin. Punctures bearing long, curved, golden, recumbent setae. Coarse, sparse granules between punctures on disc; granules close anterolaterally.

Elytra: Slightly elongate, broadest close to middle, subparallel in middle third, then narrowing strongly in posterior third, to acuminately rounded apex. Punctures of rows ( Fig. 3 C) very coarse; deeper anteriorly, shallower and smaller in middle third; obsolete towards apex. Puncture rows striate impressed ( Fig. 3 C); intervals raised, shining, with medium, fine punctures and transverse wrinkles; coarsely granulate in posterior third and along margins (e.g. Fig. 3 C). Punctures of rows and intervals bearing long, curved, golden, recumbent setae. Scutellum relatively elongate, 2x as long as broad; shining, no evident microreticulation; sparsely and finely punctate.

Venter: Entire surface with dense plastron vestiture, except posterior genae and central portion of metaventrite and abdominal ventrites 1–4; thorax and abdomen with long, curved, golden, recumbent setae and rounded to elongate-oval, coarse, shining granules. Anterior prosternal emargination broad, relatively shallow. Prosternal process approximately 1.2x length of anterior portion of prosternum; quadrate, with raised lateral margins and close, coarse punctures; apex broadly truncate. Fovea at junction of meso and metaventrites large and circular, occupying almost entire lateral portion of mesoventrite. Metaventrite shining, with no visible microreticulation and coarse, close, rugose punctures. Sternite 9 with posterior portion 0.66x length of anterior median strut.

Legs: Meso and metatibiae with characteristic modifications ( Fig. 4 C, F).

Aedeagus: Phallobase relatively short, 0.6x length of penis. Penis longer than parameres, relatively broad; curved apically in lateral view, with truncately acuminate apex. Parameres narrow, with acuminate apices, and slightly curved interior margins (see Fig. 5 C).

Females: As males, except for slightly shallower mesoventral concavity and lack of tibial modifications. Ovipositor elongate, distal gonocoxite relatively stout ( Fig. 6 C); equal in length to proximal gonocoxite.

Variation: Specimens vary somewhat in the extent of dorsal setation, setae having been lost from sections of some individuals.

Differential diagnosis. Distinguished from L. georyssoides and L. gibbosus sp. nov. on the basis of larger body size, more evident setation and differences in elytral shape ( Fig. 1 ), together with details of pronotal ( Fig. 2 ) and elytral ( Fig. 3 ) sculpture and sexual modifications ( Fig. 4 ). The aedeagus of L. hirsutus sp. nov. is longer and stouter than that of both other species, as well as differing in detail ( Fig. 5 ). The ovipositor of L. hirsutus sp. nov. is also relatively large ( Fig. 6 ), with equal-length proximal and distal gonocoxites.

Distribution and ecology. Known only from the type locality ( Fig. 7 B), a cold, permanent stream within the snow line in the Groote Winterhoek mountains in the Western Cape Province. This stream also yielded two new species of Hydraenidae : Mesoceration helmei Bilton, 2015 and Sebasthetops altimontanus Bilton, 2015 ( Bilton 2015a, 2015b).

Etymology. Named in reference to the long, golden dorsal setae, which give this species a relatively hairy appearance.

Figures

FIGURE 1. Leielmis species, male habitus. A) L. georyssoides; B) L. gibbosus sp. nov., holotype; C) L. hirsutus sp. nov., holotype. Scale bar = 1 mm.

FIGURE 2. Leielmis species, pronotal sculpture. A) & D) L. georyssiodes; B) & E) L. gibbosus sp. nov.; C) & F) L. hirsutus sp. nov. A) – C) scanning electron micrographs; D) – F) stacked macrosope images.

FIGURE 3. Leielmis species, Elytral sculpture, scanning electron micrographs. A) L. georyssoides; B) L. gibbosus sp. nov.; C) L. hirsutus sp. nov.

FIGURE 4. Leielmis species, male tibial modifications, dorsal view A) & D) L. georyssoides; B) & E) L. gibbosus sp. nov.; C) & F) L. hirsutus sp. nov. A) – C) mesotibiae; D) – F) metatibiae. Scale bar = 0.25 mm.

FIGURE 5. Leielmis species, aedeagi, ventral and lateral views. A) L. georyssoides; B) L. gibbosus sp. nov.; C) L. hirsutus sp. nov. Scale bar = 0.25 mm.

FIGURE 6. Leielmis species, ovipositors, distal gonocoxites. A) L. georyssoides; B) L. gibbosus sp. nov.; C) L. hirsutus sp. nov. Scale bar = 0.25 mm.

FIGURE 7. Leielmis species, habitats. A) Western Cape, Table Mountain, stream in Echo Valley, L. georyssoides; B) Western Cape, Groote Winterhoekberge, Stream below Sneeugatpiek, L. gibbosus sp. nov. & L. hirsutus sp. nov.; C) Western Cape, stream at Mont Rochelle above Franschhoek, L. gibbosus sp. nov. Photos D. T. Bilton & N. Helme.