Sharphydrus brincki, Bilton, 2013

Bilton, David T., 2013, A taxonomic revision of South African Sharphydrus, with the description of two new species (Coleoptera: Dytiscidae: Bidessini), Zootaxa 3750 (1), pp. 26-36 : 28-31

Sharphydrus brincki sp. nov.

( Figs 1A – 3A )

Type locality. South Africa, Western Cape, Cederberg, Matjiesrivier Reserve, Matjies River ca. 3 km N of Cederberg Oasis, 32 31 10.86S 19 21 02.91E, 727 m. ( Fig. 3A ) .

Type material. Holotype (male): “ 21/ix/2010 South Africa WC, Cederberg , Matjiesrivier Reserve, Matjies River ca. 3 km N of Cederberg Oasis, D. T. Bilton leg.” (genitalia extracted and mounted in DMHF on same card) with red printed holotype label “ Holotype Sharphydrus brincki sp. nov. Bilton” ( ISAM).

Paratypes (12♂, 13♀): 7♂, 7♀ same data as holotype ; 2♀ “ 22/ix/2011 South Africa WC, Cederberg , Matjiesrivier Reserve, Matjies River ca. 3 km N of Cederberg Oasis, D. T. Bilton leg.” ; 1♀ “ 23/ix/2012 South Africa WC, stream ca. 2 km S of Eselbank on Wupperthal Road , D. T. Bilton leg.” ; 4♂, 3 ♀ “ 22/ix/2010 South Africa WC, stream ca. 1 km along Witsenberg Valley road W of Jnctn with 303 at Gydopas, D. T. Bilton leg.” ; 1♂ “ S. Afr. Cape Prov., Gydo Pass, 10 miles N. Ceres, 12.11.51, No. 180/ Swedish South Africa, Expedition, 1950- 1951, Brinck-Rudebeck// Type [round label, red ring]// Sharphydrus capensis Type ♂ O-C [Omer-Cooper HW]// 1985, 365 [blue label]// Not real type material [red label, Biström HW]// Sharphydrus capensis (O-C.), O Biström det. 1985// MZLU, 2013, 264 [green label]” (5♂, 6♀ CDTB, 1♂, 1♀ MZLU; 1♂, 1♀ NHM; 1♂, 1♀ NMW; 1♂, 1♀ UMO; 1♂, 1♀ ISAM; 1♂, 1♀ DMSA; 1♂, 1♀ SANC). All with my red printed paratype labels “ Paratype Sharphydrus brincki sp. nov. Bilton” .

Description. Size: Holotype: body length (to elytral apices) 2.7 mm; max. width (elytra) 1.45 mm. Elytral length 2.1 mm. Same values for paratypes: 2.65–2.75, 1.4–1.5 and 2.05–2.2 mm respectively.

Colour ( Fig. 1A ): Dorsal surface predominantly yellowish brown. Head and pronotum slightly more deeply pigmented than ground colour of elytra. Hind margin of pronotum with a black band, this being thickest between the lateral plicae, where it is approximately 1/5–1/4 pronotal length in extent. Black band narrower towards centre of pronotum. Front margin of with a dark band, this usually being blackish, but at least infuscated, as in some paratypes; always clearly visible. Elytra with diffuse blackish markings, with rather ill-defined boundaries. Area between discal carinae and suture predominantly dark in posterior half. Elytral pattern somewhat more diffuse in some paratypes, where dark marks are reduced to rather ill-defined infuscations, but always present. Palpi and legs uniformly pale yellowish brown. Antennae also pale yellowish brown, with segments 6–11 infuscated apically, this being particularly marked on segments 7–11. Venter with pronotum and elytral epipleurs pale yellowish brown, remainder infuscated, particularly in males.

Head: Broad, with large eyes. Clypeus somewhat thickened and evenly rounded, but lacking anterior border, and not separated from rest of head. Well-developed shallow, open fovea present on each side of head, anterior to eye, just behind clypeus. Cervical line well marked between hind portion of eyes. Head in front of cervical line with distinct, coarse punctures, each bearing a small peg-like seta at its centre. Punctures smaller and sparser on clypeus, becoming larger and denser towards cervical line, where they are approximately 3x the diameter of those on the clypeus. Punctures from the frons backwards becoming confluent, giving a longitudinally coriaceous appearance. Head microreticulate except on the central frons, which is smooth. Head microreticulate on clypeus, front of frons, and around eyes. Microreticulation transverse on clypeus and behind sutural line; isodiametric around eyes. Remainder of head smooth and shining between punctures. Apical segments of maxiliary and labial palpi narrowly truncate, and somewhat flattened dorsoventrally at apices.

Pronotum: Transverse rectangular. Sides rounded; widest just before middle. Hind margins distinctly bisinuate around middle. Lateral plicae well developed, relatively deep, and open interiorly. Plicae deepest at posterior ends; sinuate and becoming shallow anteriorly, here extending to approximately 1/2 away from front margin of pronotum. Pronotal surface rough, with coriaceous appearance, due to coarse, dense, sometimes almost confluent punctation, each puncture bearing a small peg-like seta as on head. Punctures particularly dense towards centre of pronotal disc, where they are separated by ridges only. Pronotal surface smooth between punctures; without visible microreticulation.

Elytra: Together forming an elongate oval, with point of maximum width just behind middle. Lateral margin rounded to front angles, somewhat subparallel in middle, and tapered towards apex in posterior half. Elytra with well-developed discal keels running posteriorly from base of pronotal lateral plicae to just over 2/3 elytral length. Carinae robust and high; maximum height being towards the middle of the keel. Elytral suture also raised over discal region; area between keels and suture relatively flat ( Fig. 1A ). Each elytron with a row of long, fine, recumbent setae interior to keel, positioned approximately 1/3 way towards suture, and running for length of keel (setae are apparently lost and invisible in some paratypes). Entire elytral surface, including keels, with dense, coarse punctation, giving a coriaceous appearance. Punctures almost confluent in places (e.g. close to keels), and each puncture bearing a small peg-like seta. No visible microreticulation between punctures.

Venter: Anterior margin of prementum with short, stout setae and scattered longer hair-like setae behind. Mentum will well developed blunt truncated medial tooth. Surface of mentum with fine transverse ridges, but otherwise lacking apparent microreticulation. Submentum with transverse furrows and scattered punctures, but lacking microreticulation. Gular sutures weak, but gular region distinct due to absence of microreticulation. Remainder of underside of head with weak isodiametric reticulation, which is obsolete on genae and towards the outer margins of the mandibles. Pronotal hypomeron smooth and shining, with very few scattered punctures. Prosternum smooth and shining with confluent punctures, particularly at the base of the prosternal process, an area also furnished with long, hair-like setae. Prosternal process strongly raised, neck of process forming an angle of approximately 70° with prosternum. Process elongate, cordiform, flat, with a broad shallow groove occupying 3/4 of process width. Neck of process with setae; process itself with punctures bearing short, peg-like setae. Prosternal process reaching anteromedial process of metaventrite. Metaventrite with weakly defined groove in rear half. Coxal lines well-marked, subparallel, diverging anteriorly. Hind coxal margin bisnuate; coxal lobes weak, not covering leg insertions. Ventral surface of meso- and metathorax and abdomen, elytral epipleurs with dense, coarse punctation, each puncture bearing a short peg-like seta. Punctures very dense and almost confluent on hind coxae and abdominal ventrites; elsewhere spaced at most 1–1.5 puncture widths apart. Punctures absent only from hind margins of hind coxae, here traces of isodiametric microreticulation visible; spaces between punctures otherwise smooth. Fourth and fifth abdominal ventrites with long hair-like setal bunches at their centres.

Aedeagus: Median lobe characteristically shaped and pigmented ( Fig. 2A ); trilobate at apex, with curved, ventrally-directed process, and short lateral lobes, lobes rounded in ventral view. Parameres ( Fig. 2A ) twosegmented, with bluntly curved, hooked tips.

Females: As males except head, pronotum and elytra entirely microreticulate between punctures, giving a much duller, more obviously coriaceous appearance. Fore and mid tarsi slightly narrower and noticeably shorter than in males, particularly last tarsal segment.

Variability. Paratypes vary slightly in size (see above) and the development of the elytral pattern, some specimens being darker than the holotype.

Distribution. To date known from the type locality ( Fig. 3A ), and a nearby stream in the south-eastern part of the Cederberg range, and further south from a small stream just to the west of Gydopas above Ceres, all in the Western Cape region (see Fig. 4 ). Much of the area in which the new species has been collected in represents a transition zone between mountain fynbos and karroo vegetation.

Etymology. Named after Professor Per Brinck, who was the first person to collect this species in 1951. The specific epithet is a noun in the genitive case.

Ecology. Beetles were taken from backwaters and pools in drying rivers, being most abundant in deeper (ca. 40 cm) water with some scattered reeds. Here they co-occurred with a range of water beetles, including, at Matjies River, Hydropeplus montanus Omer-Cooper , Herophydrus inquinatus (Boheman) , Hyphydrus signatus Sharp , Yola frontalis Régimbart , Hydroglyphus infirmus (Boheman) , H. lineolatus (Boheman) , Canthyporus guignoti Omer- Cooper, C. petulans Guignot , Philaccolus lineatoguttatus (Régimbart) , Laccophilus lineatus Aubé , Hydaticus capicola Aubé , Aulonogyrus capensis (Thunberg) , Berosus punctulatus Boheman , Laccobius (Hydroxenus) spp., Helochares spp. , Crenitis zimmermanni Knisch , Parasthetops nigritus Perkins & J. Balfour-Browne , P. pampinus Perkins , P. rufulus Perkins & J. Balfour-Browne and Prosthetops wolfbergensis Bilton. At Eselbank the new species co-occurred with Agabus ruwenzoricus Guignot , Hydropeplus montanus , Canthyporus bicinctus (Régimbart) , C. guignoti , C. petulans , Laccophilus lineatus , Hydaticus capicola , Aulonogyrus marginatus (Aubé) , A. splendidulus (Aubé) , Hydrochus sp. and Parasthetops nigritus , and west of Gydopas with Agabus ruwenzoricus , Hydropeplus montanus , Canthyporus bicinctus , C. petulans , Hyphydrus signatus , Yola frontalis , Aulonogyrus splendidulus and Parasthetops nigritus .

Figures

FIGURE 1. Habitus of A) Sharphydrus brincki sp. nov. B) S. kamiesbergensis sp. nov. C) S. capensis. D) S. coriaceus. Dorsal and lateral views. Scale bar = 1 mm.

FIGURE 2. Male genitalia of Sharphydrus species: median lobe in lateral and ventral view, right paramere of: A) S. brincki sp. nov.; B) S. kamiesbergensis sp. nov.; C) S. capensis; D) S. coriaceus. Scale bar = 0.5 mm

FIGURE 3. Type localities of: A) Sharphydrus brincki sp. nov. South Africa, Western Cape, Cederberg, Matjiesrivier Reserve, Matjies River ca. 3 km N of Cederberg Oasis; B) S. kamiesbergensis sp. nov. South Africa, Northern Cape, Kamiesberg, stream on Witwater–Langkloof road ca. 1 km S of junction. Photos D.T. Bilton.

FIGURE 4. Distribution of Sharphydrus species in South Africa: yellow symbols S. brincki, green symbol S. kamiesbergensis, red symbols S. capensis, white symbols S. coriaceus. Closed circles indicate specimens examined, open circles records from the literature.