Canthyporus pallidus Bilton, 2015, sp. nov.
Creators: name: Bilton, David T.
Publisher: name: Zenodo
Year: 2015
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Coleoptera
Dytiscidae
Canthyporus
Canthyporus pallidus

description: Canthyporus pallidus sp. nov.
(Figs 1–5)
Type locality. South Africa, Western Cape Province, Gifberg, Gifberg Pass, seepages on vertical rockfaces, 31°45'47.93''S 18°46'15.01''E, 485 m. (Fig. 5 A).
Type material. Holotype (male): “ 20/ix/2014 South Africa WC// Gifberg—vertical wet rock face// in Gifberg Pass nr. Vanrhynsdorp// D T Bilton leg.” (genitalia extracted and mounted in DMHF on same card) with red printed holotype label “ Holotype // Canthyporus pallidus sp. nov. // Bilton” (ISAM).
Paratypes: 3 ♂, 12 ♀ same data as holotype; 1 ♂, 1 ♀ “ 20/ix/2014 South Africa WC// Gifberg—stream in Gifberg Pass// above Vanrhynsdorp// rocky stream D T Bilton leg.”; 1 ♂, 1♀ “ 21/ix/2014 South Africa WC// Matsikammaberg seepage stream// over rock at head of Elandskloof// D T Bilton leg.”; 1 f # “ 21/ix/2014 South Africa WC// Matsikammaberg stream// 1 km NW of Sewefontein farm// D T Bilton leg.”; 2 ♂, 4 ♀ “ 21/ix/2014 South Africa WC// Matsikammaberg stream// 1 km SE of Sewefontein farm// permanent D T Bilton leg.”; 1 ♀ “ 21/ ix/2014 South Africa WC// Matsikammaberg rockpools// on NE edge of plateau// D T Bilton leg.”; 2 ♀ “ 17/ix/ 2014 South Africa NC// Kamiesberg—seepages over// rock below summit of Johannes// se Berg ca. 1,470 m D T Bilton leg.”; 1 ♀ “ 18/ix/2010 South Africa NC// seepages on rockface on R27 road// @ Vanrhynspas D T Bilton leg.” (CDTB, DMSA, ISAM, LUMZ, NMW, SANC, OUMNH). All with red printed paratype labels “ Paratype // Canthyporus pallidus sp. nov. // Bilton”.
Description. Size: Holotype: body length (to elytral apices) 2.4 mm; maximum width (elytra) 1.3 mm; elytral length 1.8 mm. Same values for paratypes: 2.3–2.5 mm, 1.25–1.3 mm and 1.65–1.9 mm respectively.
Colour (Fig. 1 F): Dorsal surface predominantly yellowish to reddish ferrugineous. Head ferrugineous, infuscated very narrowly around inner margins of compound eyes. Pronotum yellowish-pale ferrugineous, slightly darker in centre; narrowly dark brown along posterior margin. Elytra yellowish, with irregular dark brown spots and markings. Antennae yellow, apical portions of segments infuscated, more so distally. Maxillary palpi yellow, apical segment infuscated in distal 1/3. Legs yellow. Venter of head ferrugineous; pronotal hypomeron, proepisternum and elytral epipleura dark yellowish; remainder of venter pitchy brown to black.
Head: Broad, with large eyes. Anterior margin of clypeus weakly rounded. Frontal depressions very shallow, punctate, opening anteriorly. Surface shining, with moderately shallow isodiametric microreticulation. Punctation fine and sparse; scattered larger punctures close to anterior border of clypeus and around inner margins of compound eyes. Antennal segments short and stout; segments 3–4 narrower than remainder.
Pronotum: Rectangular, strongly transverse, broadest at posterior angles. Anterior margin weakly arcuate; posterior margin bisinuate around centre. Lateral margins converging towards anterior angles; weakly arcuate and narrowly bordered. Anterior angles acute; posterior angles rectangular. Surface shining, with shallow isodiametric microreticulation; very finely and sparsely punctate. Irregular transverse row of coarse punctures along anterior margin, each bearing a fine decumbent seta. Similar punctures present along posterior margin in outer 1/3.
Elytra: Slightly elongate ovate, broadest at middle, relatively flat and broad. Rounded at sides, more strongly so in posterior 1/2. Surface shining, with shallow isodiametric microreticulation and fine, sparse punctation. Sutural puncture row distinct, particularly in posterior 2/3; formed by a row of depressions around relatively finemedium punctures, giving the impression of a shallow stria when viewed from behind. Discal, dorsolateral and lateral puncture rows with somewhat irregular, widely spaced coarse punctures; punctures much larger than in sutural row.
Venter: Prementum shining, finely wrinkled. Mentum shining, with raised, slightly elongate microreticulation on anterolateral projections; weakly wrinkled elsewhere. Mentum broadly concave, produced laterally to form a dome around centre. Gula shining, lacking microreticulation. Genae shining, with shallow transverse microreticulation. Pronotal hypomeron broad; this and proepisternum both shining and finely wrinkled. Prosternum and neck of prosternal process shining, rugose and punctate, punctures with long, recumbent, golden setae. Neck with bunch of erect setae approximately 1/2 distance along length. Prosternum and neck of process forming a more or less continuous angle of approximately 45° with venter. Prosternal process elongate, spathulate, laterally beaded. Lateral bead punctate, punctures bearing fine decumbent setae, which lie on medial surface. Medial surface convex, impunctate, smooth and shining; apex located in impression in metaventrite. Metaventrite and metepisternum shining, finely wrinkled and with very fine, sparse punctation. Metaventrite with traces of shallow, transverse microreticulation. Elytral epipleura shining, with shallow, isodiametric microreticulation in outer 2/3, with a shining inner ridge lacking microreticulation. Epipleurs as broad as pronotal hypomeron at shoulders, narrowing evenly to level of metacoxae and continuing as narrow ridge to apex. Metacoxae shining, with shallow isodiametric to elongate microreticulation, more evident that on metaventrite; finely and sparsely punctate. Metacoxal lines strong, arcuate, diverging anteriorly; punctate, punctures bearing long, decumbent setae. Metacoxal fissure narrow but distinct. Metacoxal process free, lobes rounded and strongly diverging laterally. Abdominal ventrites shining, microreticulate. Ventrites 1–3 fused, junctions weakly visible, but segments distinct due to changes in microreticulation. Microreticulation more or less isodiametric on ventrite 2, elongate on ventrite 2 and transverse on ventrite 3. Ventrites 4–6 with increasingly isodiametric microreticulation; meshes weakly transverse on ventrite 4, weakly transverse to isodiametric on ventrite 6 and distinctly isodiametric on ventrite 6. Ventrites 2–4 with a central tuft of long, stout, recumbent setae, and a transverse row of 4–6 additional smaller recumbent setae running along centre.
Legs: Basal three segments of pro- and mesotarsi somewhat expanded, with suction setae ventrally. Apical segment of mesotarsi elongated, longer than apical segment of protarsi. Tarsal claws elongate, arcuate, simple; equally elongated on pro- and meostarsi.
Aedeagus: Median lobe characteristically shaped (Fig. 2 F); apex relatively truncate in ventral view. Parameres (Fig. 2 F) broad, with distinct apical tuft of setae.
Females: As males except for more strongly impressed microreticulation on dorsum and venter, as well as narrower pro- and mesotarsi, which lack suction setae. Apical segment of mesotarsi as long as in males; longer than apical segment of protarsi, which is shorter than in males. Pro- and mesotarsal claws slightly shorter than in males. Spermatheca relatively robust, broad, stout (Fig. 3 E).
Variation: Paratypes vary slightly in size (see above) and the development of the dorsal pattern, some specimens being somewhat darker or lighter than the holotype. All specimens lack any distinctly darker dorsal colouration on the head and pronotum. They vary in the extent to which a sutural puncture row is visible. In some cases this is clear, as in the holotype, in others the row is weak, and only visible as a series of somewhat larger punctures in posterior 1/3.
Differential diagnosis. Another member of the exilis group (see above), closest to C. nebulosus and C. brincki. Differs from nebulosus by the uniformly pale head and pronotum (both always distinctly infuscated in nebulosus —see Fig. 1), the somewhat larger size (2.3–2.5 versus 1.94–2.22 mm in nebulosus), the broader, flatter dorsum, the shallower microreticulation and finer punctation, especially on the pronotum and elytra, the presence of a sutural puncture row, at least posteriorly, the more elongate apical segment of the male protarsi, as well as the broader median lobe of the aedeagus, which is also much more truncate apically in ventral view (Fig. 2). In females, the spermatheca of C. pallidus sp. nov. is more robust than that of C. nebulosus, and shorter and broader (Fig. 3). The new species differs from brincki in the more mottled appearance of the elytra (see Fig 1), the less well impressed microreticulation, giving a somewhat more shining appearance, the broader dorsum and slightly larger size (2.3–2.5 versus 2.06 mm in brincki), as well as shape of the apex of the median lobe of the aedeagus in ventral view (more rounded in C. brincki, more truncate in C. pallidus sp. nov. —see Fig. 2).
Distribution and ecology. Found in the northern part of the Western Cape and the Northern Cape provinces of South Africa. So far known from the Gifberg-Matsikamaberg massif, northwards along the Bokkeveld Escarpment (Vanrhyns Pass), to the high Kamiesberg of Namaqualand. Most records are from seepages over wet rock faces, and although some specimens are from streams. These were mostly located in shallow areas around the margins, particularly over rock. In seepage habitats the new species co-occurred with typical madicoles, such as the hydraenids Pneuminion velamen Perkins, 1997 and Pterosthetops hawequas Perkins, 2008 (see Bilton 2014).
Etymology. Named in reference to the pale colouration of the head and pronotum. It is an adjective in the in the nominative singular.
description: Published as part of Bilton, David T., 2015, A review of the Canthyporus exilis group, with the description of two new species (Coleoptera: Dytiscidae), pp. 441-454 in Zootaxa 3957 (4) on pages 446-451, DOI: 10.11646/zootaxa.3957.4.5, http://zenodo.org/record/238991