Leielmis gibbosus, 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 : 265-266

Leielmis gibbosus 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 gibbosus // Holotype // D T Bilton 2017” ( ISAM) .

Paratypes (48) 5 ♂ 12 ♀ same data as holotype ( AMG, CDTB, NMW, SANC, TMSA) ; 3 ♂ 1 ♀ “ 8/ii/2015 South Africa WC// Jonkershoek – n stream in// Kurktrekker kloof in forest// D T Bilton leg.” ( CDTB) ; 3 ♂ 3 ♀ “ 25/ix/2009 South Africa WC// Stream at 1,100 m @ Mont Rochelle // Above Franschhoek D. T. Bilton leg.” ( CDTB, ISAM) ; 1 ♂ “ ♂ ”, “ S. Africa // Harrison // Su 81 B// H.g.6” [HW], “Prépar. genit.// N o 1010635” [pink label, number HW], “ J. Delève det., 1963// Leielmis // georyssoides Gr. ” [3 & determination HW], “ I.R.Sc. N.B. I.G. 25.041// Coll. & det. J. Delève ” [specimen partly disarticulated, missing head and some legs, presumably the individual on which Delève (1964) based his description of Leielmis and georyssoides ] ( ISNB) ; 1 ♂ “ ♂ ”, “ S. Africa // Great Berg River // Upper French Hoek // Forest Reserve ”, “C. S.I. R. – Stream // Survey S 1 B// 15.9.50 ” [S1 B & date HW], “Prépar. genit.// N o 24464.4” [pink label, number HW], “ J. Delève det., 1964// L. georyssoides Gr. ” [4 & determination HW], “ I.R.Sc. N.B. I.G. 25.041// Coll. & det. J. Delève ” ( ISNB) ; 2 ♂, 2 ♀ “ ♂ ”, “ S. Africa // Great Berg River // Upper French Hoek // Forest Reserve ”, “C. S.I. R. – Stream // Survey S 1 B// 15.9.50 ” [S1 B & date HW], “ J. Delève det., 1964// L. georyssoides Gr. ” [4 & determination HW], “ I.R.Sc. N.B. I.G. 25.041// Coll. & det. J. Delève ” ( ISNB) ; 1 ♂ “ S. Africa // Great Berg River // French Hoek Forest // Reserve ”, “ Coll & det. J. Delève / / Leielmis // georyssoides Gr. // I.R.Sc ..N.B. I.G. 25.041” [determination HW] ( ISNB) ; 1 ♀ “ ♀ ”, “ S. Africa // Great Berg River // Upper French Hoek // Forest Reserve ”, “C. S.I. R.— Stream // Survey S 1 B// 15.9.50 ” [S1 B & date HW], “Prépar. genit.// N o 24464.6” [pink label, number HW], “ Coll & det. J. Delève // Leielmis // georyssoides Gr. / / I.R.Sc ..N.B. I.G. 25.041” [determination HW] ( ISNB) ; 6 ♂, 2 ♀ “ St. No. // 39” [39 HW], “ Cape Province // Swellendam,// Wolfkloof , 12.iii.1954 // in mountain stream// in deep gorge, 1500ft ”, “S. AFRICA:// Cape Province,// Swellendam District ,// J. Balfour-Browne. // B.M. 1954-797.”, “ J. Delève det., 1965// L. georyssoides Gr. ” [5 & determination HW] ( BMNH) ; 1 ♂ “ St. No. // 39” [39 HW], “S. AFRICA:// Cape Province,// Swellendam District,// J. Balfour-Browne. // B.M. 1954-797.”, “ Cape Province // Swellendam ,// Wolfkloof , 12.iii.1954 // in mountain stream// in deep gorge, 1500ft ”, “ J. Delève det., 1965// L. georyssoides Gr. ” [5 & determination HW] ( BMNH) ; 1 ♀ “ St. No. // 39” [HW], “in mountain// stream in deep// gorge, 1500ft ”, “S. AFRICA:// Cape Province,/ / Swellendam District ,// J. Balfour-Browne. // B.M. 1954-797.”, “ J. Delève det., 1965// L. georyssoides Gr. ” [5 & determination HW] ( BMNH) ; 1 ♂ “ ♂ ”, “ St. No. // 39” [39 HW], “ Cape Province // Swellendam,// Wolfkloof , 12.iii.1954 // in mountain stream// in deep gorge, 1500ft ”, “S. AFRICA:// Cape Province,// Swellendam District ,// J. Balfour-Browne. // B.M. 1954-797.”, “ Prépar. genit.// N o 222657” [pink label, number HW], “ J. Delève det., 1965// L. georyssoides Gr. ” [5 & determination HW] ( BMNH) ; 2 inds. “ S. Africa // Great Berg River // Upper French Hoek // Forest Reserve ”, “C. S.I. R.— Stream // Survey S 1 B// 15.9.50 ” [S1 B & date HW], “ J. Delève det., 1964// L. georyssoides Gr. ” [4 & determination HW] ( BMNH). All with red paratype labels “ Leielmis gibbosus // Paratype // D T Bilton 2017”.

Description. Size: Holotype: body length (front of pronotum to elytral apices) 1.55 mm; maximum width (elytra) 1.1 mm; elytral length 1.15 mm. Same values for paratypes: 1.50–1.60 mm, 1.05–1.15 mm and 0.95–1.15 mm respectively.

Colour: Dorsum ( Fig. 1 B) dark brown to black, palest at anterior margin of pronotum. Legs dark reddish brown, tarsi paler, yellowish. Antennae with segments 1–3 straw yellow, 4–11 infuscated, especially segments 9– 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, weakly microreticulate and finely granulate and punctate, punctures bearing curved, recumbent setae. Clypeus also shining, weakly microreticulate and finely granulate and punctate, punctures bearing curved, recumbent setae. Frontoclypeal suture feebly impressed; weakly arcuate. Frons shining, with moderate, medium punctures, bearing curved, recumbent setae; moderately, coarsely granulate and microreticulate. Eyes occupying approximately half side of head; rounded anteriorly, relatively flat laterally and posteriorly. Maxillary palpi with segment 3 flat and expanded laterally, approximately 2x 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 1.2x 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 B, E) shining, without evident microreticulation; doubly punctate, with moderate, medium punctures, interspersed with moderate, fine punctures, larger punctures approximately 3– 4x diameter of smaller ones. Coarse punctures bearing long, fine, golden, recumbent to decumbent setae. Coarsely granulate between punctures, except on disc.

Elytra: Slightly elongate, broadest approximately one third of the distance behind shoulder, narrowing strongly in posterior third, to acuminately rounded apex. Punctures of rows ( Fig. 3 B) relatively evenly sized throughout length. Puncture rows not striate impressed on disc; weakly striate impressed on rows 4–6. Puncture rows obsolete towards apex. Intervals relatively flat ( Fig. 3 B), shining, with microreticulation reduced to transverse wrinkles; finely punctate, punctures bearing fine, golden, recumbent setae, especially laterally and posteriorly; interval punctures of two sizes, fine and very fine, fine punctures arranged in irregular rows. Surface coarsely granulate posterolaterally. Scutellum 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 medium, curved, golden, recumbent setae and rounded to elongate-oval, coarse, shining granules. Anterior prosternal emargination relatively deep, v-shaped. Prosternal process approximately 1.2x length of anterior portion of prosternum; quadrate, with raised lateral margins and close, coarse punctures; abruptly narrowing to bluntly acuminate apex. Fovea at junction of meso and metaventrites small and circular. Metaventrite shining, with no visible microreticulation and coarse, close punctures. Sternite 9 with posterior portion 2.5x length of anterior median strut.

Legs: Meso and metatibiae with characteristic modifications ( Fig. 4 B, E).

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

Females: As males, except for slightly shallower mesoventral concavity and lack of tibial modifications. Ovipositor elongate, distal gonocoxite with relatively narrow apices ( Fig. 6 B); 0.7x length of proximal gonocoxite.

Variation: Some specimens vary somewhat in the punctation of the pronotum, the larger punctures being larger and denser in some (e.g. those from Jonkershoek) and smaller and sparser in others (e.g. Mont Rochelle). Such specimens do not differ consistently in other characters, however, and all have distinctly weaker pronotal punctation than L. georyssoides .

Differential diagnosis. See under L. georyssoides .

Distribution and ecology. This species appears to be relatively widely distributed in the interior Cape Fold Mountains, from the Groote Winterhoekberge in the north west to the Langeberg in the south east. Apparently allopatric to L. georyssoides , but, like this species, found in fast-flowing permanent mountain streams (e.g. Fig. 7 B, C). Delève (1970) also lists Angola, Huíla District, Tampa, without comment; a record repeated by Stals (2007) and Jäch et al. (2016). I have found the specimen on which this record is undoubtedly based in the BMNH, labelled: “St. No.// 274” [274 HW], “Tampa, ca. 4000ft.,// drying pools in// sandy river bed,// foul water.”, “S. AFRICA:// Angola.// Huilla District.// J. Balfour-Browne.// B.M. 1954-797.”, “J. Delève det., 1965// L. georyssoides Gr. ” [5 & determination HW], “ Leielmis gibbosus Bilton, 2017 // det. D T Bilton det. 2017”. The beetle is a typical specimen of L. gibbosus sp. nov., and seems likely to have been mislabelled, particularly given the habitat details appearing on the label. The extreme disjunction of this locality from all confirmed sites for L. gibbosus sp. nov., and the fact that Table Mountain and the interior Cape Fold Mountains support separate species of the genus, despite their much closer geographical proximity, also makes this record appear highly unlikely. I have not included this specimen in the type series of L. gibbosus , given my doubts regarding its provenance, and suggest that the record of this genus from Angola is treated as doubtful, unless new material proves otherwise.

Etymology. Named in reference to the arched, hunched habitus.

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.