Parhydraena faeni, Bilton, David T., 2014

Bilton, David T., 2014, Two new water beetles from the Hantamsberg, an inselberg in the Northern Cape of South Africa (Coleoptera, Hydraenidae), Zootaxa 3887 (3), pp. 471-480 : 475-477

Parhydraena faeni sp. nov.

( Figs 1–3 )

Type locality. South Africa, Northern Cape, Calvinia, Hantamsberg, drying stream with pools 1km N of mast on summit plateau, 31° 22’ 33.22’’S 19° 47’ 11.5’’E, 1,500 m ( Fig. 1 B–C).

Type material. Holotype (male): “ 18/ix/2010 South Africa NC// Calvinia Hantamsberg summit// pools in stream 1 km N of // mast 1,500 m D T Bilton leg.” (genitalia extracted and mounted on same card) and red holotype label ( SAM).

Paratypes (15): South Africa: 9 ♂, 2 ♀ “ 18/ix/2010 South Africa NC// Calvinia Hantamsberg summit// pools in stream 1 km N of // mast 1,500 m D T Bilton leg.” ( CDTB, NMW, SANC, TMSA); 1 ♂, 3 ♀ “ 18/ix/2010 South Africa NC// Calvinia Hantamsberg summit// drying stream on gravel on NW side// of plateau— 1,500 m D T Bilton leg.” ( CDTB, SAM). All with red paratype labels.

Description. Size: Holotype: BL 2.03 mm; EL 1.3 mm; EW 0.75 mm. Paratypes: ♂s BL 2.05–2.25 mm; EL 1.3–1.4 mm; EW 0.8–0.83 mm. ♀s BL 2.2–2.33 mm; EL 1.4–1.45 mm; EW 0.9–0.98 mm. Dorsum ( Fig. 1 B)—head dark piceous brown - black, pronotum dark straw yellow, with disc dark brown to black, elytral dark straw yellow with suture and lateral margin infuscated. Legs and maxillary palpi straw yellow; tarsi and apical palpal segment infuscated. Venter dark reddish brown to piceous, with silvery hydrofuge vestiture. Pronotal hypomeron dark straw yellow, as dorsum; inner 0.5 of bubble hypomeron dark pitchy brown. Elytral epipleurs and pseudepipleurs straw yellow as dorsum.

Head: Labrum transverse, rounder apicolaterally, with broad, shallow apicomedian emargination, running approx. 0.15 of length, and broad, rounded notch either side of apicomedian emargination, approx. 0.5 as deep as central notch. Sides of apicomedian emargination very weakly raised. Surface of labrum shining, with distinct, weakly transverse - isodiametric microreticulation and with sparse, medium punctures, each bearing a long decumbent seta. Entire upper surface of head weakly shining, with strong isodiametric microreticulation and sparse coarse to medium punctures, some of which bear long decumbent setae. Punctures densest on clypeus and central parts of frons and vertex, more widely spaced elsewhere, and somewhat obsolete around inner margins of eyes. Fronto-clypeal suture strong, well impressed. Oblique sublateral impressions strong, deeper posteriorly, shallower anteriorly. Ocelli broad and flat, paler than rest of head. Eyes large, occupying almost 0.5 side of head; facets relatively flat. Maxillary palpi elongate, approx. 1.2x length of head.

Pronotum: Cordate, strongly transverse. Anterior margin straight, slightly indented in median third, where there is a trace of a narrow hyaline border. Anterior angles obtusely rounded. Sides rounded, broadest just in front of middle, gradually narrowing in an almost straight line to obtuse posterior angles. Sides distinctly crenulate, especially in posterior 0.5. Pronotum with fine, weakly impressed isodiametric microreticulation, somewhat shining. Entire surface punctate, with dense, shallow punctures. Each puncture with anterior margin extended posteriorly as narrow ridge, dividing puncture into a pair of two smaller punctures, most punctures with indistinct, short recumbent or decumbent seta arising from posterior extreme of dividing ridge. Punctures more widely spaced in centre of disc; closer, almost confluent, towards anterior and posterior margins, giving a rugulose appearance; larger and more elongate towards lateral margins. Discal impressions weak, shallow and open.

Elytra: Elongate oval, sides weakly arcuate, broadest behind middle. Margins weakly explanate over posterior 0.8 of length, and minutely serrate. Elytra strongly and densely punctate, each puncture bearing a long recumbent white—yellowish seta (worn in places in older specimens). Each puncture with anterior margin extended posteriorly as narrow ridge which supports the seta. Elytral puncture rows not clearly discernable, punctation instead appearing subseriate to somewhat irregular. A single stria present alongside suture in posterior 0.33.

Venter: Mentum, submentum and genae shining. Mentum coarsely and rugosely punctate; punctures almost confluent towards lateral margins, and bearing long recumbent golden setae throughout, with visible traces of transverse microreticulation amongst punctures. Submentum with similar setose punctures; more widely spaced than on Mentum, with only faintest traces of microreticulation lines. Genae with rugose microreticulation towards sides; transverse corrugations internally. Gula dull, punctate, with rugose, isodiametric microreticulation; punctures bearing recurved golden setae. Prosternum with similar microreticulation and punctation in anterior 0.5; punctate only, and therefore shiny in posterior 0.5. Surface with long recurved setae, becoming denser anteriolaterally. Pronotal hypomera broad, shining. Wet hypomeron with open, weak, isodiametric reticulation; bubble hypomeron smooth, lacking vestiture in outer 0.5, rugose and pubescent in inner 0.5. Meso and metaventrites rugosely microreticulate, punctate, with long hydrofuge vestiture, densest laterally. Basal 0.5 of metaventrite with weak longitudinal carina, barely visible amonst the vestiture. Elytral pseudepipleurs broad, flat, shining, narrowed approx. 0.4 from base. Epipleurs narrow, with hydrofuge vestiture in anterior 0.4. Abdominal ventrites 1–4 microreticulate; covered in long hydrofuge vestiture; ventrite 5 with same vestiture and sculpture in anteriorly 0.33, sculpture and vestiture extending to 0.5 length of sclerite centrally. Posterior part of ventrite 5 glabrous and shining, with isodiametric microreticulation anteriorly, and transverse meshes posteriorly. Irregular transverse row of medium punctures bearing decumbent setae approx. 0.33 from apex of ventrite. Ventrite 6 entirely glabrous, shining, with weakly transeverse microreticulation over anterior 0.5; lacking microreticulation in posterior 0.5; two sections separated by a transverse ridge, and three irregular transverse rows of decumbent setae. Last ventrite asymmetrical, with rounded tooth-like projection on right, which fits between the lobes of the last tergite. Last tergite with apicomedian notch, flanked by tufts of short, stout setae.

Legs: Moderately long and slender, basal 3 pro- and mesotarsomeres with pads of suction setae.

Aedeagus: Strongly arcuate in lateral view; slightly sinuate in ventral view. Main piece with large, transverse, flattened ventral process. Distal piece complex, with articulated apical lobes. Gonopore tube distinct, relatively robust for the genus, and projecting beyond the apex of the distal piece. Parameres with long, robust setae ( Fig. 1 D).

Female: Last ventrite with simple, rounded apex; last tergite with slight apical emargination, but lacking obvious notch. Tarsi without suction setae.

Variation: Paratypes vary somewhat in colouration and in the depth of the discal impressions, which are sometimes more marked than those of the holotype.

Differential diagnosis. Parhydraena faeni sp. nov. can be distinguished from other described species of the genus by the indistinct elytral series, which result in an irregularly punctate appearance. The pale colouration and male genitalia of the new species are also characteristic. The only other described species with similarly subseriate or irregular elytral punctures is Parhydraena sebastiani Perkins , which has very different surface sculpture, colouration and aedeagus ( Perkins, 2009). This is apparently the largest known species of the genus, some females exceeding 2.3 mm.

Distribution. To date only known from two adjacent localities on the summit of the Hantamsberg, close to Calvinia, in Hantam Plateau Dolerite Renosterveld (sensu Mucina & Rutherford, 2006). Here the species was abundant amongst gravel and marginal vegetation in pools in temporary stream systems (see Fig. 3 ).

Etymology. Named in reference to the straw yellow colouration of the dorsum.

Figures

FIGURE 1. Habitus and genitalia of Hantamsberg Hydraenidae. A) Mesoceration hantam sp. nov., holotype; B) Parhydraena faeni sp. nov., holotype; C) Mesoceration hantam sp. nov., aedeagus, ventral and lateral view; D) Parhydraena faeni sp. nov., aedeagus ventral and lateral views. Scale bar A – B = 1 mm; C – D = 0.25 mm.

FIGURE 2. Southern margin of the Hantamsberg plateau, showing its isolation from the surrounding plains. The yellow flower in the foreground is likely Moraea reflexa Goldblatt, endemic to the Hantamsberg. Photo D. T. Bilton.

FIGURE 3. Water beetle habitats on the Hantamsberg plateau, 1,500 m. A) Drying stream pool on gravel on northwest side of plateau; B) pool in stream 1 km north of mast; C) detail of residual pool in same stream system; D) temporary pool on clay / rock with Bulbinella nutans. Photos D. T. Bilton.