Pterosthetops pulcherrimus, 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: 449-451

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Pterosthetops pulcherrimus

sp. nov.

Pterosthetops pulcherrimus   sp. nov.

( Figs 3 View FIGURE 3 B & 4 B)

Type locality. South Africa, Western Cape, Cederberg mountains, wet rock face in Uitkyk Pass above Algeria, D.T. Bilton leg. ( Fig 5 View FIGURE 5 C).

Type material. Holotype (male): “ 21 /ix/ 2010 South Africa WC// Cederberg Uitkyk Pass above// Algeria—rockface seepages// D T Bilton leg.” (genitalia extracted and mounted on same card) and red holotype label ( SAM). Description. Size: Holotype: BL 2.2 mm; EL 1.3 mm; EW 0.85 mm. Dorsum ( Fig. 3 View FIGURE 3 B) dark brown to black, explanate elytral margins somewhat paler. With a dark greenish metallic sheen on head, pronotum and elytra. Maxillary palpi pitchy brown, legs dark reddish brown; femoro-tibial junctions and tarsi slightly darker. Venter predominantly dark piceous, with silvery hydrofuge pubescence.

Head: Labrum transverse, with rounded sides and thickened lateral margins, and open, U-shaped apicomedian emargination, running approx. 0.3 of length. Sides of apicomedian emargination distinctly raised. Anterior margins of labrum strongly raised; curled over dorsally either side of apicomedian emargination. Surface of labrum dull, with strong microreticulation and stout decumbent setae around apical and lateral margins. Clypeus, frons and much of vertex with strong, punctulate microreticulation; punctulae larger, deeper and more confluent towards lateral margins of frons and clypeus and on vertex. Raised areas of frons shining, at most with scattered, shallow punctulae between shallow, irregularly shaped setal sockets, which bear short, decumbent setae. Frontoclypeal suture narrow, but well-marked. Centre of frons, anterior to ocelli, with scattered larger punctures, each with a short, flat decumbent seta. Areas surrounding these punctures shining, devoid of small punctures, but with traces of microreticulation lines. Frons with a central elevation, broken by a broad circular concavity between and immediately behind the ocelli; steeper anteriorly, shallower posteriorly. Ocelli well-marked, shining. Arcuate sulci running from just in front of each ocellus towards the front of the eyes, where they are broad and open. Frons weakly raised and thickened anterior to eyes. Eyes large, occupying just under 0.5 of the lateral margins of the head; 11 convex facets in longest series.

Pronotum: Distinctly cordate, with broadly and strongly explanate sides, furnished with small depressed setae. Anterior angles obtusely rounded. Sides very weakly crenulated and weakly to sharply arcuate over anterior 0.75, then almost straight to rectangular posterior angles ( Fig. 3 View FIGURE 3 B). Anterior margin rounded, with very weak hyaline border in middle. Posterior margin bisinuate to centre. Explanate areas of anterior pronotum shining, with traces of obsolete microreticulation and scattered decumbent setae. Convex discal area shining outside fovea, the transverse microreticulation being restricted to central region, immediately behind anterior margin. Close, coarse punctures on pronotal disc, each bearing a flattened decumbent seta. Transverse fields of larger, deeper punctures close to anterior and posterior pronotal margins.

Median longitudinal sulcus deep, foveate anteriorly and posteriorly; posterior fovea approx. 2 x depth of anterior fovea. Anterior fovea elongate; posterior more rounded. Both foveae with strong, isodiametric reticulation. Posterior admedian fovea elongate, with similar microreticulation to median sulcus. Anterior admedian fovea shallow and open; punctate. Adlateral fovea strong, deep and pit-like; trace of a longitudinal channel linking anterior and posterior fovea.

Elytra: Elongate, with rounded shoulders and apex. Weakly rounded at sides, and broadest in middle. Explanate lateral margin narrow in front, but broad elsewhere. Apices separately rounded. Each elytron 10 -seriate punctate; punctures relatively large and deep towards the front, somewhat smaller and shallower in rear 0.2. Each elytron with a shallow, transverse depression (saddle) close to middle, occupying intervals 1–3; saddle extending forward over intervals 1 & 2; entire depression occupying almost 0.3 of elytral length. Punctures of elytral series still distinct in saddle, despite the presence of some punctures in the intervals of the saddle region. Elytral intervals 1–6 raised over much of their length, each with an additional row of seriate punctures, almost as large as those of the elytral striae. Each interval puncture bearing a long, fine, white recumbent and apically-directed seta, intact setae reaching at least as far as the posterior margin of the next puncture in the row. Interval 2 broadly raised in front of saddle; weakly so behind it, anterior to the confluence of series 1 and 2. Interval 3 broadly raised in front and behind saddle; flat in posterior 0.2 of elytron. Interval 4 clearly raised immediately behind anterior margin and alongside elytral saddle; flat in front of saddle and very weakly raised in posterior half of elytron. Interval 5 raised throughout; more weakly so in posterior 0.3. Interval 6 raised only in front of saddle. Interval 8 narrower than intervals 1–7, raised from just in front of middle. Entire elytral surface shining; lacking microreticulation.

Venter: Mentum shining, with a trace of microreticulation, scattered median punctures and setae. Submentum also shining; devoid of microreticulation, with scattered punctures, bearing long decumbent setae at margins. Genae shining, with open, transverse microreticulation in front of weak transgenal ridges; smooth behind. Gular region shining, with a trace of transverse reticulation lines on centre, but with well-impressed transverse microreticulation towards posterior margin. Pronotal hypomeron shining, wrinkled, with a trace of microreticulation. Prosternum wrinkled, dull, with a central ridge, and long, dense hydrofuge vestiture, particularly towards lateral margins. Meso and metaventrites with well-developed squamose hydrofuge vestiture; vestiture longer towards lateral margins. Mesoventral plaques narrow but visible, glabrous. Medial plaque forming an inverted Y. Border between mesoventrite and anepisternum 2 marked by a narrow glabrous ridge. Metaventrite with shallow, broad longitudinal depression over rear 0.5 of sternite; pit-like longitudinal fovea in centre. Elytral pseudepipleurs broad and flat; shining with a trace of 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 small triangular patches of hydrofuge setal vestiture anterio-laterally. Ventrite 1 also with hydrofuge setae below hind coxae; these setae resembling those on lateral and hind margins of metaventrite. Ventrites 1–5 shining, entirely devoid of microreticulation. Ventrites 5 & 6 with transverse row of long, adpressed hair-like setae, positioned 0.6 of the way down the sternite; punctures largest on ventrite 6. Ventrite 6 shining, but with shallow, open transverse microreticulation.

Aedeagus: Elongate, curved in lateral view, with parameres attached near base, and extending well beyond apex of main piece. Main piece with curved, beak-like apex, asymmetrical in ventral view. Ventral setae of main piece very long and stout. Distal lobe elongate and sinuous; tube like, curved in lateral and ventral view, and extending slightly beyond apices of parameres ( Fig. 4 View FIGURE 4 B).

Female: Unknown.

Differential diagnosis. Recognized by a combination of the shining elytra, which lack microreticulation, the long, single elytral saddle, the long recumbent setae in rows on the inner elytral intervals and the first elytral interval being flat in the saddle region. Male genitalia characteristic (see Fig. 4 View FIGURE 4 B).

Distribution. Known to date only from the type locality, a wet rock face in Uitkyk Pass, one of the wettest areas of the Cederberg range in the Western Cape region ( Fig. 9 View FIGURE 9 ).

Etymology. Named in reference to the striking, shining appearance and the view from the type locality ( Fig. 7 View FIGURE 7 C).


South African Museum