Mesoceration sewefonteinense, Bilton, David T., 2015

Bilton, David T., 2015, New species and new records of Mesoceration Janssens, 1967 from South Africa (Coleoptera, Hydraenidae), Zootaxa 3972 (4), pp. 495-520 : 506-511

Mesoceration sewefonteinense sp. nov.

( Figs 3 , 4 & 6 )

Type locality. South Africa, Western Cape, Matsikammaberg, permanent stream 1 km SE of Sewefontein farm ( Fig. 6 A).

Type material. Holotype (male): “ 22/ix/2014 South Africa WC// Matsikammaberg stream// 1 km SE of Sewefontein farm// permanent D T Bilton leg.” (genitalia extracted and mounted on same card) and red holotype label ( SAM).

Description. Size: Holotype: BL 1.4 mm; EL 0.8 mm; EW 0.5 mm.

Colour: Dorsum ( Fig. 3 B) reddish to pitchy brown, ocelli and pronotal margins paler. Legs and maxillary palpi pale yellow. Venter pale red to piceous brown; head and prothorax lighter, meso and metaventrites and elytral epipleurs darker.

Head: Labrum slightly transverse, rounded apicolaterally with broad, V-shaped apicomedian emargination over 0.5 of length. Sides of apicomedian emargination distinctly raised, anterior margins less so. Surface shining, with shallow, open, longitudinal microreticulation and scattered medium punctures bearing long, decumbent setae. Frontoclypeal suture weak but visible, arcuate. Clypeus somewhat shining, with coarse, transverse microreticulation and scattered punctures bearing decumbent setae. Centre of frons shining, with somewhat granulated isodiametric microreticulation and coarse punctures bearing decumbent setae. Vertex microreticulate, rugulose. Anteocellar furrows open laterally; furrows and areas between them and compound eyes rugulose. Ocelli flat, shining. Compound eyes relatively large, occupying approx. 0.6 lateral margin of head, 12 ommatidia in longest series.

Pronotum: Cordate, quadrate, widest in front of middle. Anterior margin arcuate over central 0.5, no hyaline border; posterior margin weakly bisinuate around centre. Anterior angles broadly rounded; posterior angles rectangular. Lateral margins sinuated from widest point to base; broadly marginated and weakly serrate. Entire upper surface somewhat shining, with isodiametric microreticulation, somewhat granulate on reliefs; scattered medium punctures bearing decumbent setae. With 10 distinct foveae as follows: Anterior median fovea elongate, deeper posteriorly, almost meeting oval posterior median fovea; the two separated by an area lower than the lateral reliefs. Anterior admedian fovea shallow, oval; posterior admedian fovea very shallow, elongate oval, orientated anterolaterally. Anterior and posterior adlateral foveae circular, posterior deeper than anterior.

Elytra: Elongate oval, broadest at middle, subparallel over central 0.6 then attenuated to broadly rounded apex. Suture slightly produced. Lateral margins narrowly explanate and minutely serrate. Elytral series with punctures becoming smaller towards apex; not striate impressed. Punctures shallow, with decumbent setae reaching next puncture in row; series granulate in front of punctures. Series 1 and 2 confluent at posterior declivity; series 5 and 6 confluent in anterior 0.3. Series 8 carinate from shoulder almost to apex. Intervals strongly granulate, particularly in basal 0.3, but granules continuing beyond posterior declivity; granules bearing decumbent setae which reach next granule in row.

Legs: Apical protarsomere with two long, stout ventral setae, one longer and stouter than the other; basal three protarsomeres with suction setae.

Venter: Mentum somewhat shining, with strong microreticulation composed of slightly elongate meshes. Anterior and lateral margins sharply depressed relative to centre. Submentum shining, with weak, isodiametric microreticulation. Mentum and submentum with scattered, elongate, decumbent setae. Genae shining, transversely wrinkled, especially laterally. Gula shining, with fine transverse microreticulation posteriorly. Prosternum with low, glabrous central ridge, widened over posterior 0.5. Rest of surface rugulose, with dense hydrofuge vestiture. Pronotal hypomeron broad, dull, with weak isodiametric microreticulation. Mesoventrite and metaventrite dull, with dense hydrofuge vestiture. Mesoventral plaques forming an inverted Y, stem shorter than arms. Stem and posterior 0.5 of arms broad, flat; anterior 0.5 of arms narrower. Low admedian and adlateral ridges also present, but covered by vestiture. Metaventrite with broad, shallow median fovea over posterior 0.5 and small semicircular glabrous patch between metacoxae; anterior of metaventrite with low M-shaped ridge below mesocoxae. Elytral pseudepipleurs weakly shining, traces of microreticulation; epipleurs narrow, shining, ridge-like. Dense patch of longer, erect hairs visible at base of abdomen, between interior borders of metacoxae. Abdominal ventrites 1–4 with dense hydrofuge vestiture. Abdominal ventrite 5 with glabrous patch occupying approx. 0.2 of ventrite, semicircular around centre. Junction between pilose and glabrous areas marked by a row of punctures bearing long, decumbent setae. Abdominal ventrite 6 glabrous, weakly shining, with open, isodiametric microreticulation; irregular row of short, decumbent setae 0.2 from apex.

Aedeagus: Elongate, with parameres attaching close to base and extending just beyond the apex of the main piece. Distal lobe short, funnel-shaped in ventral view, with open membranous apex—unique within the genus to date ( Fig. 4 B).

Female: Unknown

Differential diagnosis. A member of the endroedyi group sensu Perkins & Balfour-Browne (1994). The species would key to M. dissonum Perkins and Balfour-Browne, 1994 in this work, since the granules of the median elytral intervals continue beyond the posterior declivity. M. sewefonteinense sp. nov. differs in its more elongate, parallel-sided habitus, paler dorsal and ventral colouration, duller, more strongly granulate elytra, head with stronger microreticulation on frons, and the very different, and so far unique, structure of the aedeagus.

Distribution. To date known only from the type locality ( Fig. 6 A), a permanent stream section running through Bokkveld Sandstone Fynbos (sensu Mucina & Rutherford 2006) close to Sewefontein farmhouse on the Matsikammaberg at the northern edge of the Core Cape Floristic Region ( Manning & Goldblatt 2012). The Matsikammaberg is a striking inselberg, reaching just over 1,000 m in altitude, with 700 m high sandstone cliffs towering over the dry Knersvlakte plains of Namaqualand. The mountain forms a mesic island in an otherwise semi-arid landscape, annual rainfall reaching 550 mm in the east contrasting with as little as 50 mm per year on the plains below. The Matsikammaberg is consequently home to a diverse flora, 10% of which is regionally, and 4% locally endemic ( Helme 2004).

Etymology. Named in reference to the type locality. Sewefontein translates as seven springs in English.

Figures

FIGURE 3. Habitus of Mesoceration holotypes. A) M. rugulosum sp. nov.; B) M. sewefonteinense sp. nov.; C) M. sinclairi sp. nov.

FIGURE 4. Aedeagi of Mesoceration species. A) M. rugulosum sp. nov., holotype; B) M. sewefonteinense sp. nov., holotype; C) M. sinclairi sp. nov., holotype; D) M. littlekarroo, Swartberg, permanent stream below Kangoberg on Gamkaskloof road. Scale bar = 0.25 mm

FIGURE 6. Habitats of Mesoceration species in South Africa. A) Western Cape, Matsikammaberg, permanent stream 1 km SE of Sewefontein farm— M. foggoi sp. nov., M. sewefonteinense sp. nov., M. umbrosum; B) Western Cape, False Bay, small stream on R 44 road below Boskloof Peak— M. sinclairi sp. nov., M. brevigranum; C) Western Cape, Groote Swartberg, permanent stream below Kangoberg on Gamkaskloof road— M. barriotum, M. littlekarroo, M. reticulatum, M. splendorum; D) Western Cape, Table Mountain National Park, Table Mountain, stream in Echo Valley— M. abstrictum, M. tabulare. Photos D. T. Bilton.