Parhydraena semicostata, Perkins, 2009

Perkins, Philip D., 2009, Revisions of the genera Parhydraena Orchymont, Protozantaena Perkins, Decarthrocerus Orchymont, and Parhydraenopsis nomen novum, aquatic and humicolous beetles from Africa and Madagascar, and comparative morphology of the tribe Parhydraenini (Coleoptera: Hydraenidae), Zootaxa 2038, pp. 1-119 : 30-31

Parhydraena semicostata new species

( Figs. 55, 57, 97)

Type material. Holotype (male): South Africa: Mpumalanga Province, Soutpansberg, Entabeni , shore washing, 22° 58' S, 30° 15' E, 15.iii.1973, Endrödy-Younga (#56). Deposited in the TMSA . Paratypes (45): South Africa: Limpopo Province, Eastern Transvaal, Piesanghoek substitute: GEN 162J 225900S 300500E, stones in current, 22° 59' S, 30° 5' E, (1 TMSA) ; N. Transvaal, Blaauwberg , on damp rocks of stream in forest, elev. 1767 m, 23° 8' S, 28° 56' E, 19.iv.1954, J. Balfour-Browne (41 BMNH) ; Mpumalanga Province, Blouberg , 23° 5' S, 29° 0' E, 9.i.1955, C. Rudebeck (1 BMNH) ; N. Transvaal, Louis Trichardt , 22k W., river stones, 23° 2' S, 29° 40' E, 1–5.iv.1976, Endrödy-Younga & L. Schulze (#1125) (1 TMSA) ; N. Transvaal, Soutpansberg Entabeni , from river bed, 22° 58' S, 30° 15' E, 15.iii.1973, Endrödy-Younga (#55) (1 TMSA) .

Differential diagnosis. Recognized among members of the genus by the semicostate elytra, the comparatively short maxillary palpi (palpus length/head width ca. 0.59) with rather wide last palpomere, and the coarsely and densely punctate pronotum. Distinguished from P. lancicula by the larger size (length ca. 1.84 mm vs. 1.76 mm), the narrower body form, and the more deeply striate-impressed elytra ( Figs. 50, 55). The distinctive 5th abdominal ventrite of males, having a large saucer-like modification, is similar to that of P. lancicula . The aedeagi of the two species also suggest a relationship ( Figs. 52, 57).

Description. Size (length/width, mm) holotype: body (length to elytral apices) 1.84/0.80; head 0.30/0.53; pronotum 0.45/0.70, PA 0.59, PB 0.58; elytra 1.11/0.80. Head and pronotal disc piceous, area surrounding pronotal disc brown; elytra, legs and maxillary palpi dark brown, apex of distal mere of maxillary palpus not darker than remainder of palpus.

Head with eyes moderately large, in dorsal aspect 9 convex facets in longest series. Ocelli distinct round small shining, each located at base of shallow oblique interocular fovea. Frons on disc moderately coarsely punctate, ca. 1–2xef, interstices shining, 1–2xpd; area between interocular foveae and eye effacedly microreticulate, coarsely punctate, dull. Clypeus dull, microreticulate, very indistinctly punctate, except anterior margin shining. Labrum dull, as long as clypeus, apicomedially emarginate to form rounded lobe on each side; laterally fringed with short arcuate setae. Maxillary palpi moderately short, combined lengths of meres less than width of head (ratio ca. 22/37); ratios of meres 2–4 ca. (8/4/11). Mentum and submentum densely finely punctulate, microreticulate. Metasternum with moderately deep median elongate oval impression in posterior 2/3, midlongitudinal carina between anterior extreme of oval impression and mesoventral intercoxal process.

Pronotum with anterior margin very weakly arcuate, median 1/3 with extremely narrow hyaline border. Anterior angles obtuse, moderately angulate. Sides rounded, widest at middle, behind middle gradually attenuate, very weakly sinuate. Posterior angle obtusangulate. Pronotum coarsely and very densely punctate, rugulose, but with most interstices shining, discal relief more finely punctate, ca. 1xef, interstices smooth and shining. Discal impressions deep, broadly U-shaped, many punctures confluent; rather deep, wide impression at each posterior angle. Each puncture with anterior margin extended posteriorly as narrow ridge, dividing puncture into a pair of two smaller punctures, most punctures with short recumbent or decumbent seta arising from posterior extreme of dividing ridge.

Elytra elongate-ovate, sides weakly arcuate, margins distinct from shoulder for 4/5 of length. Ten-seriate punctate, series weakly striate-impressed, intervals raised, semicostate; punctures ca. 2–3xef, longitudinally separated by ca. 1xpd or less, becoming finer and shallower on posterior declivity, most punctures with minute granule at anterior margin. Interval width ca. 2xpd, shining, each with unilinear row of rather widely spaced, minute granules, each granule at its posterior side with short recumbent seta, setae very similar in length and density to setae of serial punctures.

Metaventrite and abdominal ventrites 1–4 hydrofuge pubescent. Ventrite 5, in male, hydrofuge pubescent in basal 1/4 laterally, posterior margin of pubescent area extended in middle to 1/2 length of ventrite, posterior edge of 5th at middle raised into a distinct semicircular projection hiding middle of 6th in repose; in female basal 1/3 of ventrite hydrofuge pubescent; shining part of ventrite 5 very sparsely pubescent in both sexes. Ventrite 6 microreticulate, dull, simple in both sexes. Male: last ventrite asymmetrical, apex weakly lobiform and setose; last tergite with tuft of setae on each side of apicomedian notch into which fits lobe of last ventrite. Female: last ventrite sparsely pubescent, margin rounded; last tergite with apical margin rounded, bearing moderately long setae.

Legs stout, moderately short, combined lengths of metatibia and metatarsus greater than width of head (ratio ca. 43/37), ratio of lengths of metatibia/metatarsus ca. 25/18, claws moderately short. Basal 3 pro- and mesotarsomeres, in male, with pad of suction setae.

Wings fully developed in holotype and all dissected males.

Aedeagus length ca. 0.35 mm; main-piece, in ventral view, with process on left side shorter than largest of two process on right side; distal piece multi-lobed in ventral view, in left lateral view largest lobe markedly pointed ( Fig. 57).

Etymology. Named in reference to the semicostate elytra.

Distribution. Currently known from Soutpansberg, and areas not too distant in Mpumalanga Province and Limpopo Province ( Fig. 97).