Mesoceration sinclairi, 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 : 511-513

Mesoceration sinclairi sp. nov.

( Figs 3 , 4 & 6 )

Type locality. South Africa, Western Cape, False Bay, small stream on R44 road below Boskloof Peak ( Fig. 6 B). Type material. Holotype (male): “ 3/x/2014 South Africa WC//Kogelberg—stream with seepages along R44 road// D T Bilton leg.” (genitalia extracted and mounted on same card) and red holotype label ( SAM).

Paratypes (26) 12 ♂ 14 ♀ same data as holotype ( CDTB, MCZ, NMW, OUMNH, SAM, SANC, TMSA). All with red paratype labels.

Description. Size: Holotype: BL 1.4 mm; EL 0.85 mm; EW 0.55 mm. Paratypes: ♂s BL 1.4–1.5 mm; EL 0.85–0.9 mm; EW 0.55–0.57 mm. ♀s BL 1.45–1.55 mm; EL 0.9–1.0 mm; EW 0.55–0.65 mm.

Colour: dorsum ( Fig. 3 C) dark piceous brown to black, ocelli paler. Legs and maxillary palpi orange-yellow; last segment of maxillary palpi infuscated in apical 0.6. Venter dark piceous brown to black, with silvery hydrofuge vestiture on much of thorax and abdomen. Head paler, mentum, basistipes and palpifer yellowish-red.

Head: Labrum slightly transverse, rounded apicolaterally, with apicomedian emargination running approx. 0.4 of length. Sides of apicomedian emargination and anterior angles weakly raised. Surface shining, with shallow, open microreticulation and scattered, long, decumbent setae, especially towards posterior margin. Frontoclypeal suture arcuate, shallow but distinct. Clypeus, frons and vertex shining. Clypeus with strong, open, isodiametric microreticulation, stronger laterally, and with scattered decumbent setae. Central frons with traces of microreticulation and scattered, coarse, shallow punctures bearing long, decumbent setae. Anteocellar sulci deep, open laterally; sulci and areas between them and compound eyes rugulose, with coarse, impressed isodiametric microreticulation. Ocelli shining, prominent. Compound eyes relatively small, occupying ca. 0.3 lateral margin of head, 12 ommatidia in longest series.

Pronotum: Cordate, slightly transverse, broadest at middle. Anterior margin arcuate over median 0.4, without hyaline border; posterior margin slightly rounded. Anterior angles obtusely rounded; posterior angles broadly rectangular. Lateral margins sinuated from widest point to base; broadly marginated and weakly crenulate. Surface shining, lacking microreticulation except for narrow strip of transverse microreticulation along central 0.5 of anterior margin, and shallow isodiametric microreticulation in foveae. With 10 distinct foveae as follows: Anterior median fovea elongate; posterior median fovea oval. Anterior admedian fovea shallow, oval, open laterally; posterior admedian fovea shallow, elongate oval, orientated anterolaterally. Anterior and posterior adlateral fovea deep, pit-like, anterior open laterally. Anterior and posterior 0.2 of disc with sparse, coarse, deep punctures over central 0.5, these extending into front 0.5 of anterior median and anterior admedian foveae. Most punctures bearing long, pale, decumbent setae. Pronotal reliefs with scattered fine-medium punctures bearing similar setae.

Elytra: Elongate, widest just behind shoulders, then parallel-sided over approx. 0.3 of length, then attenuated to apex. Apex rounded, apical angles distinct, acutely rounded. Sides narrowly explanate, especially anteriorly, entire. Punctures of elytral series relatively coarse; larger in anterior 0.5, smaller posteriorly. Discal series striate impressed in anterior 0.6, series 5 and 6 also striate impressed posteriorly. Serial punctures with fine decumbent setae, not usually reaching next puncture in row. Series 1 and 2 confluent at posterior declivity, and becoming closely subparallel in basal 0.3. Series 5 and 6 confluent in anterior 0.3. Intervals 1–5 with a row of fine punctures, each puncture bearing a long, fine, decumbent setae; reaching and partly overlapping next seta in row. Intervals 2– 4 weakly raised in anterior 0.3; interval 8 carinate to approx. 0.2 from apex.

Legs: Apical protarsomere with two stout ventral setae; basal three protarsomeres with suction setae.

Venter: Mentum weakly shining, with elongate-isodiametric microreticulation and scattered stout yellow setae. Submentum weakly shining, with traces of microreticulation and fine, scattered punctures. Genae shining, with transverse wrinkles, becoming transverse meshes of the microreticulation laterally. Gula shining anteriorly with transverse ridges, dull posteriorly with fine transverse microreticulation. Prosternum with distinct central glabrous ridge, broader posteriorly between procoxae. Rest of surface rugulose, with dense hydrofuge vestiture. Pronotal hypomeron broad, smooth and shining, lacking microreticulation; shallow, round fovea close to inner anterolateral angle. Mesoventrite and metaventrite with dense hydrofuge vestiture. Mesoventral plaques glabrous, forming an inverted Y; admedian and adlateral ridges also present but covered in vestiture. Metaventrite with elongate median fovea over posterior 0.5 and small semicircular glabrous patch posteromedially; paired, rounded admedian foveae anteriorly, below mesocoxae. Lateral areas of metaventrite, below outer angles of mesocoxae strongly depressed, almost foveate. Elytral pseudepipleurs broad, shining, narrowing to apex over posterior 0.5; epipleurs narrow, ridge-like. Abdominal ventrites 1–4 with hydrofuge vestiture; denser laterally and sparser centrally. Abdominal ventrite 5 with vestiture in basal 0.5, and semicircular smooth, glabrous, shining area in posterior 0.5; transverse row of punctures bearing decumbent setae 0.5 way down glabrous section of ventrite. Abdominal ventrite 6 glabrous, shining, with weak transverse microreticulation and double transverse row of medium punctures bearing decumbent setae 0.25 from apex.

Aedeagus: Elongate, straight in ventral view, with parameres attaching close to base and extending just beyond the apex of the main piece. Main piece with stout, rectangular apical tooth on left side, partly overhanging base of distal lobe. Distal lobe elongate, with expanded base and arcuate apex, directed leftwards in ventral view, extending beyond the apices of the parameres ( Fig. 4 C).

Female: Broader than male, especially on elytra, which have more broadly explanate lateral margins. Elytral apex more pointed, more strongly acuminate; roof-like around suture. Elytra with small depression on disc where series 1 and 2 become confluent. Microreticulation on head and pronotum stringer than in males. Abdominal ventrite 5 with broad, shining, glabrous patch over central 0.5, running from approx. 0.1 behind anterior margin. Impunctate and lacking microreticulation; posterior margin thickened and rounded.

Variation: Paratypes vary in size, but are otherwise relatively uniform in structure.

Differential diagnosis. A member of the endroedyi group sensu Perkins & Balfour-Browne (1994). Distinguished by a combination of reduced pronotal microreticulation, of which only traces can be seen on the shining reliefs, the well-impressed elytral series composed of relatively large punctures, which are striate impressed on the disc, and the shining elytral intervals, which lack visible granules, and which are raised in places. The aedeagal morphology is most like that of M. dissonum Perkins & Balfour-Browne, 1994 and M. littlekarroo Perkins, 2008 . M. sinclairi sp. nov. differs from both species in having a broader, more truncate apical tooth on the main piece, and a differently-shaped distal lobe, which is smaller and finer apically than in M. dissonum and shorter and curved more basally than in M. littlekarroo (see Fig. 4 C & D). Both these species are also readily distinguished from M. sinclairi sp. nov. externally on account of their strongly microreticulate pronotal reliefs, and M. littlekarroo by its strongly microreticulate frons.

Distribution. To date known only from the type locality ( Fig. 6 B), a small trickling stream in a shaded gulley beside the R44 road below the Kogelberg Range, on the eastern shores of False Bay. Here the species occurred with Mesoceration brevigranum .

Etymology. Named after my long-time friend Magnus Sinclair, who was instrumental in supporting my early interest in beetles.

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.