Pterosthetops indwei, Bilton, David T., 2014

Bilton, David T., 2014, New species and new records of Pterosthetops: eumadicolous water beetles of the South African Cape (Coleoptera, Hydraenidae), Zootaxa 3811 (4), pp. 438-462 : 443-444

Pterosthetops indwei sp. nov.

( Figs 1 B &2B)

Type locality. South Africa, Western Cape, Langeberg mountains, wet rock face along R324 road in Tradouw Pass ca. 10 km S. of Barrydale, D.T. Bilton leg.

Type material. Holotype (male): “ 19/ix/2009 South Africa WC// Stream and wet rock face along// R324 road in Tradouw Pass, Langeberge// Ca. 10 km S. Of Barrydale// D T Bilton leg.” (genitalia extracted and mounted on same card) and red holotype label ( SAM).

Paratypes (7): South Africa: 2 ♂, 3 ♀ “ 19/ix/2009 South Africa WC// Stream and wet rock face along// R324 road in Tradouw Pass, Langeberge// Ca. 10 km S. Of Barrydale// D T Bilton leg.” ( CDTB, SAM, SANC); 1 ♂, 1 ♀ “ 31/xii/2013 South Africa WC// Outeniquaberg Robinson Pass// wet rock face beside stream// D T Bilton leg.” ( CDTB). All with red paratype labels.

Description. Size: Holotype: BL 2.15 mm; EL 1.45 mm; EW 0.8 mm. Paratypes: ♂s BL 2.2–2.25 mm; EL 1.4–1.5 mm; EW 0.8–0.82 mm. ♀s BL 2.25–2.4 mm; EL 1.45–1.55 mm; EW 0.82–0.85 mm. Dorsum ( Fig. 1 B) dark brown to black with a dark metallic sheen on head, pronotum and elytra; particularly marked on elytra. Maxillary palpi black, legs chestnut to pitchy brown; femora and tarsi darker than tibiae. Venter predominantly dark piceous, with silvery hydrofuge pubescence.

Head: Labrum transverse, with thickened and slightly elevated anterior margin, and marked apicomedian emargination, running approx. 0.5 of length. Sides of apicomedian emargination distinctly raised. Surface of labrum dull, with well-marked microreticulation and stout decumbent setae around apical and lateral margins. Clypeus, frons and vertex with strong, punctulate microreticulation. Fronto-clypeal suture weak but visible; stronger laterally. Scattered stout, decumbent setae, except in depressions, and particularly towards lateral margins of frons. Setae stouter and longer on lateral margins of frons and clypeus, where the anterior rims of setal sockets are slightly raised. Frons with a central elevation, broken by a slightly elongate concavity between the wellmarked, shining ocelli, and arcuate sulci running from just in front of each ocellus towards the lateral corners of the frontoclypeal suture, then opening onto clypeus. Frons and clypeus with weakly raised and thickened lateral margins in front of eyes. Eyes large, occupying slightly less than 0.5 of the lateral margins of the head; 11 convex facets in longest series.

Pronotum: Distinctly cordate, relatively arched, with strongly explanate sides. Anterior angles obtusely rounded. Sides weakly crenulated and weakly to sharply arcuate over anterior 0.75, then almost straight to rectangular posterior angles ( Fig. 1 B). Anterior margin almost straight, with very weak hyaline border in middle, which is scarcely visible. Posterior margin weakly bisinuate to centre. Upper surface, with the exception of raised areas between posterior coarse punctures, with weak, isodiametric microreticulation; meshes transverse towards anterior and posterior margins. Median longitudinal sulcus foveate anteriorly and posteriorly; posterior fovea approx. 2x depth of anterior fovea. Anterior fovea elongate; posterior more rounded. Sides of sulcus raised posteriorly and anteriorly. Anterior admedian fovea shallow, transverse and open towards the front and sides. Posterior admedian fovea deep, elongate, well-marked and orientated anteriolaterally. Adlateral fovea small, rounded and deep, opening somewhat anteriorly. Posterior adlateral fovea deeper than anterior ones. Front and rear of pronotal disc with transverse fields of coarse, setose punctures, most bearing a small flat, decumbent seta. Punctures becoming larger towards posterior margin. Lateral and central areas of pronotum with short decumbent setae; anterior rims of setal sockets elevated.

Elytra: Elongate, with rounded shoulders and apex. Sides straight and parallel-sided in middle 0.3; rounded to apex in apical 0.3. Broadest just behind middle. Narrow explanate lateral margin present from shoulder to apex. Apices truncately rounded. Each elytron 10-seriate punctate, and with a shallow, transverse depression (saddle) just behind middle, occupying intervals 2–4. Additional, very shallow depression adjacent to saddle, occupying intervals 5–7. Punctures of elytral striae each bearing a small seta. Puncture rows 1–2 more irregular in saddle; confluent on right elytron but not left in holotype. Intervals raised, particularly towards elytral apex. Interval 8 more prominently raised than adjacent intervals. Each interval with a row of short, decumbent setae, these usually being situated on a small, apically-directed tubercle. Entire elytral surface shining; lacking microreticulation.

Venter: Mentum rather shining, with open microreticulation. Submentum also shining, with weaker microreticulation. Genae with open, obsolete microreticulation in front of weak transgenal ridges; more marked and strongly transverse towards sides and rear. Gular region with well-impressed, isodiametric reticulation. Pronotal hypomeron shining, lacking microreticulation, with scattered stout setae towards anterior margin. Prosternum finely rugose, with a well-marked central ridge, and distinct hydrofuge vestiture, particularly towards lateral margins. Meso and metaventrites with well-developed squamose hydrofuge vestiture; vestiture shorter and less dense towards lateral and hind margins. Mesoventral plaques visible, glabrous, but dull. Border between mesoventrite and anepisternum 2 marked by a glabrous ridge. Metaventrite with distinct longitudinal depression over rear 0.6 of sternite; depression of even depth—not foveate. Elytral pseudepipleurs shining and lacking microreticulation. Epipleurs narrow and ridge-like; shining. Abdominal ventrites 1–4 fringed with long, closely-set squamiform setae at hind margins. Ventrites 1–5 with a triangular patch of hydrofuge setal vestiture anteriolaterally. Ventrite 1 also with hydrofuge setae below hind coxae, and narrowly along much of anterior margin; these setae resembling those on lateral and hind margins of metaventrite. Central area of ventrites smooth and generally lacking microreticulation. Ventrites 5 & 6 with transverse row of long, adpressed hair-like setae, positioned 0.75 of the way down the sternite. Posterior part of ventrite 5, behind the transverse setal row, with open, transverse microreticulation. Similar reticulation also present on ventrite 6.

Aedeagus: Elongate, sinuous in lateral view, with parameres attached near base, and extending well beyond apex of main piece. Main piece characteristically shaped, long, medially situated, ventrally-directed apical process, resembling a bird’s beak, and a distinct raised shoulder to the left of this process in ventral view. Distal lobe elongate and sinuous, curved in lateral and ventral view, and extending slightly beyond apices of parameres ( Fig. 2 B).

Female: Without significant differences from males.

Variation: The male paratype from the Outeniquaberg has the ventral projection of the aedeagus slightly less upturned at the apex in lateral view. Otherwise paratypes differ slightly in size, as documented above.

Differential diagnosis. Recognized by a combination of the shining elytra, which lack microreticulation, the short, single elytral saddle, the strong microreticulation and lack of distinct punctures on the pronotal disc and (compared to Pterosthetops swartbergensis sp. nov), the relatively arched pronotum with deeper sulcus and fovea. Male genitalia characteristic; differing from P. swartbegensis sp. nov. in the shape of the apex of the main piece, and the attachment site of the apical process (see Fig. 2 B).

Distribution. Known to date only from the Langeberg and Outeniquaberg, adjacent east-west orientated mountain ranges in the Western Cape region ( Fig. 8 ).

Etymology. Named after the Blue Crane ( Anthropoides paradiseus ( Lichtenstein)) - the Indwe in isiXhosa - in reference to the bird-like shape of the aedeagus in lateral view, and the cranes seen below the Langeberg on the day the holotype was collected.

Figures

FIGURE 1. Habitus of Pterosthetops holotypes. A) P. coriaceus sp. nov.; B) P. indwei sp. nov.; C) P. swartbergensis sp. nov. Scale bar = 1 mm.

FIGURE 2. Aedeagi of Pterosthetops holotypes. A) P. coriaceus sp. nov.; B) P. indwei sp. nov.; C) P. swartbergensis sp. nov. Scale bar = 0.5 mm.

FIGURE 8. Distribution of Pterosthetops species in the Western Cape: red symbols P. br i nc k i, green symbols P. equestrius, yellow symbols P. hawequas, white symbols P. indwei sp. nov., blue symbol P. swartbergensis sp. nov. Basemap source: ESri, GigitalGlobe, GeoEye, i-cubed, USDA, USGS, AEX, Getmapping, Aerogrid, IGN, IGP, Swisstopo and the GIS User Community.