Leielmis georyssoides ( Grouvelle, 1890 )

Bilton, David T., 2017, A revision of the South African riffle beetle genus Leielmis Delève, 1964 (Coleoptera: Elmidae), Zootaxa 4254 (2), pp. 255-268 : 257-264

Leielmis georyssoides ( Grouvelle, 1890)

( Figs 1–7 )

Type locality. “cap de Bonne Espérance”.

Type material. The type series ( SANC) consists of ten specimens, originally mounted on two cards. One card supported 3 ♂ and 1 ♀, the other 3 ♀, 3 individuals whose sex could not be determined and one gap, from which a specimen has presumably been dislodged historically. I have removed the third male from the left from the first of these cards, remounted it separately, following genital dissection, and here designate it as the Lectotype: “ PART OF SYNTYPE SERIES // Helmis georyssoides Grouvelle, 1890 // Recognised as such: R. Stals, 2015.”, “NATIONAL COLLECTION OF INSECTS ( SANC)// Pretoria, South Africa ”, “ SANC TYPS 00594 ” [green label], “ Helmis georyssoides Grouvelle, 1890 // Lectotype // D T Bilton des. 2017” [red label]. Genitalia dissected and mounted in DMHF on same card; left elytron mounted separately beside specimen ( SANC) .

Paralectotypes (9): 2 ♂, 1 ♀ [mounted on one card] “ 4 Gr ” [HW], “ PART OF SYNTYPE SERIES // Helmis georyssoides Grouvelle, 1890 // Recognised as such: R. Stals, 2015.”, “NATIONAL COLLECTION OF INSECTS ( SANC)// Pretoria, South Africa ”, “ SANC TYPS 00594 ” [green label], “ Helmis georyssoides Grouvelle, 1890 // Paralectotype D T Bilton des. 2017” [red labels] ; 3 ♀, 3 inds [mounted on one card] “ PART OF SYNTYPE SERIES // Helmis georyssoides Grouvelle, 1890 // Recognised as such: R. Stals, 2015.”, “NATIONAL COLLECTION OF INSECTS ( SANC)// Pretoria, South Africa ”, “ SANC TYPS 00594 ” [green label], “ Helmis georyssoides Grouvelle, 1890 // Paralectotype // D T Bilton des. 2017” [red labels]. All specimens lack locality labels, but the original description ( Grouvelle 1890) states “..cap de Bonne Espérance par M. L. Péringuey ..”.

Additional material examined: 13 ♂, 6 ♀ “ 12/ii/2015 South Africa WC// TMNP Table Mountain // stream in Echo Valley // D T Bilton leg.”, “ Leielmis georyssoides ( Grouvelle, 1890) // D T Bilton det. 2016” ( AMG, CDTB, ISAM, SANC) ; 1 ♂, 1 ♀ “ 24/ix/2010 South Africa WC// TMNP Table Mountain // stream in Echo Valley // D. T. Bilton leg.”, “ Leielmis georyssoides ( Grouvelle, 1890) // D T Bilton det. 2016” ( CDTB) ; 7 ♂, 7 ♀ “ RSA, West Cape: Table Mtn //[= 35.58S / 18.28E] bei Kir // stenbosch, Skeleton Gorge ,// 300 bis 700 m NN. 4.3.1997 // Hess & Heckes leg.”, “ Leielmis georyssoides ( Grouvelle, 1890) // D T Bilton det. 2016” ( NHMW) ; 3 ♂ “REP. OF SOUTH AFRICA // Capetown, Table Mtn.,// stream nr. Reservoir // 27.2.1997 // G Challet ”, “ Leielmis georyssoides ( Grouvelle, 1890) // D T Bilton det. 2016” ( NHMW) ; 1 ♂ “STN 5” [HW], “S AFRICA// Cape Province // Cape District.// J. Balfour-Browne // B.M. 1954-797.” [HW], “Kirstenbosch.// 28.ii.1954 // ‘nearly dry waterfall// and stream.’” [HW], “ J. Delève det., 1965// L. georyssoides Gr. ” [5 & determination HW], “ Leielmis georyssoides ( Grouvelle, 1890) // D T Bilton det. 2016” ( BMNH) ; 1 ♀ “ ♀ ”, “Stn No.// 9” [9 HW], “ Blinkwater falls ,// in running water// (dry season) 1650 ft.// 2.iii.1954 ”, “ S. Africa. // Cape Province.// Cape District. // J. Balfour-Browne. // B.M.

1954-797.”, “J. Delève det., 1964// L. georryssoides [sic!] Gr.” [4 & determination HW], “ Leielmis georyssoides ( Grouvelle, 1890) // D T Bilton det. 2016” (BMNH); 1 ♂ “STN 5” [HW], “Kirstenbosch.// 28.ii.1954 // ‘nearly dry waterfall// and stream.’” [HW], “S AFRICA// Cape Province // Cape District.// J. Balfour-Browne // B.M. 1954- 797.” [HW], “ ♀ ” [sic!], “ J. Delève det., 1965// L. georyssoides Gr. ” [5 & determination HW], “ Leielmis georyssoides ( Grouvelle, 1890) // D T Bilton det. 2016” ( BMNH) .

Description. Size: Lectotype: body length (front of pronotum to elytral apices) 1.55 mm; maximum width (elytra) 1.05 mm; elytral length 1.15 mm. Same values for paralectotypes: 1.05–1.55 mm, 1.0– 1.05 mm and 1.15– 1.20 mm respectively.

Colour: Dorsum ( Fig. 1 A) dark brown to black, palest at anterior margin of pronotum. Legs dark reddish brown, tarsi paler, yellowish. Antennae straw yellow, apical 3–4 segments slightly infuscated. 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, 1.7x broader than long; broadest at posterior margin, narrowing strongly to front angles; posterior margin approximately 1.4x 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 A, D) shining, without evident microreticulation; doubly punctate, with moderate to close, coarse punctures, interspersed with moderate to close, fine punctures, larger punctures approximately 7x 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 A) relatively large anteriorly, especially on disc, punctures in anterior third approximately 2x diameter of those at start of posterior third. Puncture rows weakly to moderately striate impressed over anterior half of elytra ( Fig. 3 A), especially rows 4–6. Puncture rows obsolete towards apex. Intervals relatively flat, 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 broad, relatively shallow. 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 1.5x length of anterior median strut.

Legs: Meso and metatibiae with characteristic modifications ( Fig. 4 A, D).

Aedeagus: Phallobase relatively short, 0.7x length of penis. Penis distinctly longer than parameres, curved apically in lateral view, with truncately acuminate apex. Parameres narrow, with rounded apices and slightly curved interior margins (see Fig. 5 A).

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

Variation: Specimens vary somewhat in colouration, most of the type series (including the lectotype) having the elytra more brownish in colour than others. All recently collected material is relatively dark, however, the predominant impression being of a blackish insect.

Differential diagnosis. Very similar in general habitus to L. gibbosus sp. nov. (see Fig. 1 A, B). L. georyssoides differs from this species in the denser pronotal punctation, the coarse punctures of which are individually larger (ca. 2x diameter of those of L. gibbosus sp. nov. – Fig. 2 A & B; D & E); the more striate impressed elytral puncture rows, whose punctures are larger, especially at the base ( Fig. 3 A & B); the broader, shallower anterior emargination of the mesoventrite, the larger, denser punctures of the metaventrite, and the detail of the modifications to the male meso and metatibiae ( Fig. 4 A & B). The aedeagi of the two species ( Fig. 5 A & B) also differ in detail, L. georyssoides having relatively shorter, narrower parameres, not so strongly incurved at their apices, with the tip of the penis extending further beyond the paramere apices and bearing a longer apical acumination. The distal gonocoxite of the ovipositor of L. georyssoides is stouter than that of L. gibbosus sp. nov., especially at the apex ( Fig. 6 A & B).

Distribution and ecology. Grouvelle (1890, 1895) stated that this species was collected at ‘cap de Bonne Espérance’. Delève (1964) based his description of Leielmis , and redescription of georyssoides , on material collected by A. D. Harrison in the Great Berg River, sent to him by M. H. Bertrand. He attributed this to georyssoides , without study of Grouvelle’s types, on the basis of its close overall match to the original description. Delève (1970) noted that a female Leielmis collected on Table Mountain by Per Brinck differed from his concept of georyssoides in having ‘le pronotum bien plus fortement ponctué, … les stries élytrales plus marqués’, but refrained from describing a new species in the absence of further material. The discovery of the type series in SANC shows that this Table Mountain taxon referred to by Delève is in fact the true L. georyssoides , all other Leielmis specimens belonging to other, previously undescribed species. It seems that L. georyssoides is endemic to the far southwestern Cape, perhaps to Table Mountain itself, where it appears to have been collected exclusively in permanent running waters. In 2010 and 2015, the species was abundant below stones in small riffles in a permanent mountain stream on the summit of Table Mountain ( Fig. 7 A).

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.