Oomtelecopon namaqum, Bilton, David T., 2016

Bilton, David T., 2016, Two new water beetles from the South African Cape (Coleoptera, Hydraenidae), Zootaxa 4137 (4), pp. 585-591 : 588-590

Oomtelecopon namaqum sp. nov.

( Figs 1–3 )

Type locality. South Africa, Northern Cape, Kamiesberg, stream in Langkloof ca. 15 km NE of Garies, 1,000 m, 30 29 13.09S 18 0 8 13.80E ( Fig. 3 B).

Type material: Holotype (male) “ 18/ix/2014 South Africa NC// Kamiesberg – stream in// Langkloof ca. 1,000m // D T Bilton leg.” (genitalia extracted and mounted on same card) and red holotype label ( ISAM).

Paratypes (13): South Africa: 5 ♂, 8 ♀ “ 18/ix/2014 South Africa NC// Kamiesberg – stream in// Langkloof ca. 1,000m // D T Bilton leg.” ( CDTB, MCZ, NMW, ISAM, SANC, TMSA). All with red paratype labels.

Description. Size: Holotype: BL 2.8 mm; EL 1.95 mm; EW 1.4 mm. Paratypes: ♂s BL 2.55–2.7 mm; EL 1.7– 1.8 mm; EW 1.3–1.35 mm. ♀s BL 2.8–2.85 mm; EL 1.95–2.0 mm; EW 1.4–1.45 mm.

Colour: Dorsum ( Fig. 1 B) dark reddish brown to black, with dense clothing of golden arcuate setae. Legs and maxillary palpi reddish brown. Venter dark reddish brown to black, with scattered golden setae.

Head: Broadly triangular, broadest at central margin of eyes and narrowing somewhat to labral apex. Labrum slightly transverse, with shallow apicomedian emargination. Shining, with traces of granulate microreticulation, with coarse, dense punctures, each bearing a long, golden, arcuate, recumbent seta, directed posteriorly. Clypeus strongly transverse, shining, with granulate microreticulation and coarse, dense punctures bearing long, golden, arcuate, recumbent seta, directed anteriorly. Frons and vertex sculptured and punctured as clypeus. Frons with lateral setose callosity in front of each compound eye. Ocelli prominent, shining. Compound eyes raised, strongly protruding above vertex, and occupying just over 0.3 of side margin of head. Central vertex with broad cavity between compound eyes. Maxillary palpi short, last segment narrower than penultimate, bluntly pointed and narrowed to apex.

Pronotum: Transverse, sides emarginated behind protruding anterior angles, then straight to obtuse posterior angles. Hind margin broadly sinuate around centre. Disc with raised tubercles each side of centre and at centre of posterior margin. Upper surface shining, with traces of granulate microreticulation and long, golden, arcuate, recumbent setae; setae denser and longer on tubercles and along lateral margins.

Elytra: Elongate oval, widest at middle. Sides almost straight in anterior 0.2, then rounded to separately rounded apices. Elytral intervals 2, 4 and 6 with strongly setose callosities; broader and more strongly raised on intervals 2 and 4, lower and narrower on interval 6. Number of callosities can differ between left and right elytra. In holotype interval 3 has 3/4 interval 4 5/5, interval 6 5/4. Odd numbered elytral intervals with row of granules bearing long, arcuate setae, each reaching and overlapping next seta in row. Surface shining, with traces of granulate microreticulation.

Venter: Mentum transverse, narrowed slightly towards front angles. Shining, with traces of granulate microreticulation and dense, coarse punctures, each bearing a golden, arcuate, recumbent seta, directed anteriorly. Two shallow central depressions posteriorly, separated by a narrow central ridge. Submentum transverse, rugose, with scattered golden setae. Genae dull, with granular microreticulation. Cavity between lobes of genal ridges large, U-shaped. Prosternum short, with weak central carina. Pronotal hypomeron strongly setose anteriorly, with traces of granulate microreticulation; glabrous posteriorly, the two areas separated by a strong carina; traces of microreticulation on glabrous posterior section. Mesoventral process short, subpentagonal, with golden recumbent setae, directed posteriorly. Metaventrite rugosely punctured, shining, with golden recumbent setae. Traces of microreticulation between punctures. Abdominal ventrites shining, without visible microreticulation. Irregular coarse punctures present, bearing golden decumbent setae. Ventrite 1 with strong oblique carina behind each coxa. Last tergite with exposed surface vertical, free margin arcuate, lacking spines.

Legs: Tibia slender, flat on inner surface, as in other species of the genus.

Aedeagus: Elongate, parameres inserted close to base, main piece asymmetrical, with rounded apex. ( Fig. 2 B) Irregular ventrolateral expansions of main piece restricted to central 0.3 and not readily visible beyond the parameres in lateral view. Gonopore process relatively large, angled to the left in ventral view; membranous process attaching towards the centre of the apex of the mainpiece, broad, short and expanded towards the apex in lateral view. Oval internal structure visible inside main piece in ventral view, tube of gonopore process visible inside this structure (fat droplet also visible in Fig. 2 B, not present in all specimens). Parameres with setose apices, extending just beyond apex of the main piece.

Female: As males apart from slightly large average size, and stronger ventral punctation.

Variation: Paratypes vary somewhat in the height of the dorsal callosities, as well as the number in each row, which can vary between the elytra (see above).

Differential diagnosis. The new species is morphologically closest to O. disjunctum Bilton, 2015 and O. setosum Perkins, 2005 , sharing with these species the relatively humped elytra, with an abrupt posterior declivity, as well as the overall structure of the aedeagus. It can be distinguished from both species by the larger body length (2.55–2.85 mm vs. 2.23–2.55, making it closer in size to O. sebastiani Perkins, 2005 ), the broader and more strongly raised elytral callosities, the large pronotal callosities with longer, denser setae, the smaller callosities on the frons, which bear shorter setae than in O. disjunctum or O. setosum , the more evident dorsal granular microreticulation, and the coarser, denser punctation of the labrum and clypeus, which bear longer setae in O. namaqum sp. nov. The aedeagus of O. namaqum sp. nov. is also quite distinct from that of either O. disjunctum or O. setosum . In particular the main piece of the new species is much more strongly angled in lateral view. In addition, the ventrolateral expansions of the main piece are restricted to the centre of the lobe, and do not project as far dorsally as in O. disjunctum and O. setosum , and the gonopore process is longer and stouter than in either of these species (compare Fig. 2 B with Fig. 2 in Bilton (2015)).

Distribution and ecology. Known only from the type locality, a damp overhanging clay/rock bank beside a small waterfall on a stream flowing through the Langkloof, one of the wetter valleys of the Kamiesberg range.

Beetles were washed from the bank by vigorous splashing with stream water, then netted and sorted from resulting floating debris in a collecting tray. The microhabitat ( Fig. 3 B) was difficult to access, heavily shaded by riparian trees, and is likely to remain relatively cool and damp even during the dry season. The peaks and valleys of the Kamiesberg constitute one of the major centres of endemism in Namaqualand, supporting an island of fynbos vegetation which is floristically most similar to that on the Bokkeveld Plateau, 200 km further south. The high Kamiesberg is home to nearly 100 endemic plants as well as a number of endemic invertebrates, suggesting that these mountains have acted as a mesic refugium for some considerable time ( Desmet 2007).

Etymology. Named in reference to the distribution—the first species of the genus recorded from Namaqualand. The specific epithet is a noun in the genitive case.

Figures

FIGURE 1. Dorsal habitus of A) Pterosthetops nitidus sp. nov.; B) Oomtelecopon namaqum sp. nov. Scale bars = 1 mm.

FIGURE 2. Aedeagus of A) Pterosthetops nitidus sp. nov.; B) Oomtelecopon namaqum sp. nov. Scale bar = 0.5 mm.

FIGURE 3. Type localities of A) Pterosthetops nitidus sp. nov. — South Africa, Western Cape, small stream on R 44 road below Boskloff Peak, specimens collected from shaded wet rock faces at the right-hand side of the stream; B) Oomtelecopon namaqum sp. nov. — South Africa, Northern Cape, Kamiesberg, stream in Langkloof ca. 15 km NE of Garies, 1,000 m, specimen splashed from mossy area on bank below tree. Photos D. T. Bilton.