Ochthebius granulinus, Perkins, Philip D., 2011

Perkins, Philip D., 2011, New species and new collection records of aquatic beetles in the genus Ochthebius Leach from southern Africa (Coleoptera: Hydraenidae), Zootaxa 3093, pp. 1-34 : 12-15

Ochthebius (s.s.) granulinus , new species

( Figs. 7 , 8, 20 )

Type Material. Holotype (male): South Africa: Western Cape Province: Elandsdrift, shore washing, 34° 39' S, 19° 53' E, 24 ii 1981, Endrödy-Younga (#1747) ( TMSA). Paratypes (15): Western Cape Province: Same data as holotype (7 TMSA); Malmesbury District, Kalabaskraal, slow weedy stream, 33° 28' S, 18° 43' E, 27 vii 1954, J. Balfour-Browne (1 NHM); West Coast NP, Abrahamskraal, permanent lake with Juncus and weeds, 33° 14' S, 18° 8' E, 2 x 2009, D. T. Bilton (7 DTBC).

Differential Diagnosis. The dorsal habitus of this species is somewhat similar to that of O. bicomicus ( Figs. 7 , 9 ). It is differentiated therefrom by the darker dorsal color (columellae of elytra not visible) and the distinct granules on the elytral series, one granule at the anterior margin of each serial puncture. In addition, the elytral apices of O. granulinus are more acuminate, especially in females, and the body size is smaller (ca. 1.60 mm vs. 1.67 mm). The aedeagus of O. granulinus shows some resemblance to that of O. bicomicus , but differs therefrom in shape, size and orientation of the distal piece and basal ring ( Figs. 8, 10).

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.60/0.76; head 0.30/0.42; pronotum 0.42/0.58, PA 0.48, PB 0.48; elytra 0.99/0.76. Color: Head black, weakly aeneous; pronotum brown to dark brown except lighter brown narrowly along base; elytra brown, serial punctures dark brownish; venter rufopiceous, underside of head, metaventrite and apex of abdomen rufous; maxillary palpi and legs stramineous. Head: Eyes rather small, in dorsal aspect 8 weakly convex facets in longest series. Frons shining, distinctly but finely sparsely setiferously punctate, punctures 0.3xef or smaller, setae recumbent, setal length and interstices both 2– 3xef but denser near eyes; interocular foveae large, round, deep, width of each about 2/3 distance separating them, each internally with few setiferous punctures. Clypeus sculpture as frons except punctures slightly denser and sides densely pubescent. Labrum shining, very finely setiferously punctate; anterior margin apicomedially strongly upturned to form tooth. Pronotum: Subcordate, widest just behind anterior angles; anterior margin very weakly bisinuate, without postocular emarginations or processes, hyaline border well developed; sides sinuately attenuate to posterior angles; rather wide lateral hyaline border beginning just behind anterior angles, edge weakly arcuate nearly straight over median 0.8, continuing around basal angles and along base. Disc with anterior transverse impression moderately deep, outer edge of impression gradually sloping, posterior transverse impression slightly larger and deeper; disc longitudinally slightly convex between foveae; impressions densely coarsely punctate; reliefs shining, coarsely densely punctate but size and spacing of punctures quite irregular, size 1–3xef, smaller in middle of disc, interstices with exceedingly fine and sparse micropunctulate ground sculpture. Lateral depressions subrugosely strongly punctate, slope continuing transverse curvature of disc but appearing slightly inflated. Setae of discal punctures recumbent, fine and very indistinct. Elytra: Widest at middle, sides arcuate, explanate margin narrow, about equal to greatest width of tarsus. Apices narrowly separately rounded, acuminate, more distinctly in females than males. Ten-seriate punctate, series not at all striate-impressed except sutural series behind middle, on disc punctures slightly elongate, small but well impressed, slightly smaller than largest pronotal punctures, ca. 2xef, interstices ca. 1–2xpd, each puncture with anterior margin raised in form of minute granule, distally punctures progressively smaller and more longitudinally separated. Intervals flat, weakly shining, ca. 2xpd. Serial setae fine decumbent and short, each attaining base of next seta in series; nervure setae indistinct. Venter: Mentum shining, moderately sparsely setiferously punctate. Metaventrite pubescent laterally, strongly shining disc subrhomboidal, glabrous except few setiferous punctures. Abdominal ventrites 1–5 and anterior of 6 clothed with dense hydrofuge pubescence.

Etymology. Named in reference to the serial elytral granules.

Distribution. Currently known from three localities in the Western Cape Province ( Fig. 20 ).

Figures

FIGURE 7. Ochthebius granulinus, dorsal and lateral habitus of holotype.

FIGURE 9. Ochthebius bicomicus, dorsal and lateral habitus of holotype.

FIGURES 19 – 20. Geographical distributions of Ochthebius. 19. O. endroedyi. 20. O. anchorus, O. bicomicus, O. granulinus, O. involatus, and O. zulu.