Hemisphaera socotrana, Fikáček & Delgado & Gentili, 2012

Fikáček, Martin, Delgado, Juan A. & Gentili, Elio, 2012, The Hydrophiloid beetles of Socotra Island (Coleoptera: Georissidae, Hydrophilidae), Acta Entomologica Musei Nationalis Pragae 52, pp. 107-130 : 119-124

Hemisphaera socotrana sp. nov.

( Figs. 23–24 , 26–36 )

Type locality. Yemen, Socotra Island, wadi Ayhaft, 12°36.5′N 53°58.9′E, 200 m a.s.l.

Type material. HOLOTYPE: J ( NMPC): ‘ YEMEN: Socotra Isl. / wadi Ayhaft, 200m / 12°36.5′N 53°58.9′E / 7.–8.xi.2010 lgt. J. Hájek’ . PARATYPES: 10 spec. ( CDMS, IRSBN, KSEM, NHMW, NMPC): same label data as the holotype.

Description. Body widely elongate oval, moderately convex (male very slightly more convex than females), 1.2–1.5 mm long (holotype 1.3 mm), 0.6–0.8 mm wide (holotype 0.7 mm). Coloration piceous brown to black, lateral margins of pronotum and elytral apex narrowly reddish, border between reddish and dark parts vaguely defined; body venter dark brown; antenna yellowish, maxillary palpus reddish to dark reddish, with palpomere 4 darker, legs reddish.

Head transverse; clypeus slightly convex on anterior margin, bearing sparse and fine punctation, median portion with few trichobothria, interstices finely microsculptured; frons with fine and sparse punctation, bearing many trichobothria at inner margin of each eye; eyes rather small, divided by 3.8× width of each eye. Labrum well sclerotized, but inclined to ventral part of head, bearing densely arranged long setae on its surface, anterior margin with few fine spines. Mentum transverse, 2× wider than long, bearing fine mesh-like microsculpture and few setae. Maxilla with trichobothria only on basistipes, maxillary palpus rather short and stout. Antenna with eight antennomeres, pedicel and cupula enlarged, antennal club loose. Gula wide, tentorial pits weakly developed and widely isolated.

Prothorax. Pronotum transverse, with rounded antero- and posterolateral corners, lateral margin weakly convex, finely rimmed; surface with fine and sparse punctation, punctures in shape of two extremely fine pits with very short seta inbetween; trichobothria distinct, large, forming rows in along anterior margin and at midlength. Hypomeron with wide bare portion, mesal sparsely pubescent portion not divided from lateral part by ridge; prosternum very short anterior to procoxae, slightly expanded at midwidth anteriorly and posteriorly, bearing blunt median longitudinal carina, prosternal process not developed. Procoxal cavities contiguous, procoxal fissure open, notopleural suture extremely short.

Mesothorax. Scutellar shield rather large, triangular. Elytra nearly parallel-sided at midlength, with deep sutural striae distinct in apical half; each elytron bearing 10 irregular series of fine punctures, scutellary stria present; each interval with few isolated punctures of size of serial punctation, alternate intervals with trichobothria; epipleuron narrow, reaching posterior margin of metaventrite only. Mesoventrite very short, bearing transverse elevation posteriorly. Mesocoxae transverse, very narrowly isolated by mesoventral and metaventral processes.

Metathorax. Metaventrite ca. twice as long as mesoventrite, sparsely pubescent laterally, bare mesally; postcoxal ridge bent posteriad sublaterally; posterior metaventral process deeply bifid. Posterior wings present, well developed.

Abdomen with five sparsely pubescent ventrites, ventrite 1 ecarinate, bearing dense row of long setae on each side; ventrite 5 weakly concave at posterior margin.

Male genitalia. Phallobase of aedeagus long, ca. 2× longer than parameres, widest subanteriorly, slightly narrowing basad. Parameres widely subtriangular, apically membranous. Median lobe with apical portion ca. as long as basal struts, apicomedian sclerite slightly narrowing from base to narrowly rounded apex, median lobe surrounded by membranous structure subapically. Sternite 9 wide, with moderately long lateral projections, very shallow emargination on posterior margin and wide and very low median process.

Differential diagnosis. The new species may be easily distinguished from all other west Palaearctic species as well as from the African H. lima Orchymont, 1941 by the morphology of its aedeagus and the shape of sternite 9 (compare Figs. 34–36 with Figs. 37–43 ). When compared to the Mediterranean species, H. socotrana sp. nov. resembles H. guignoti Schaefer, 1975 and H. miltiadis Sahlberg, 1908 by moderately convex body and narrow, vaguely defi- ned pale coloration of sides of the pronotum and at elytral apex; its sutural stria reaches ca. midlength of elytra as in H. seriatopunctata (Perris, 1874) and H. miltiadis , and its maxillary palpus is pale with darkened palpomere 4 as in H. miltiadis . In contrast to H. socotrana sp. nov., Hemisphaera lima is much more convex in lateral view, its coloration is completely black without paler areas on sides of pronotum and at elytral apices, and it bears dark brown maxillary palpi. We were not able to compare the Socotran species with the types of H. liliputana (Régimbart, 1903) , but the single female from Madagascar present in NMPC largely differs from H. socotrana by much more depressed body, large and clearly defined yellow apical spot in apical fifth of elytra, and even elytral series consisting of much denser punctation than odd ones (in H. socotrana sp. nov., the density of punctures in all series is similar).

Etymology. The species name refers to the presence of the species in the island of Socotra. Collection circumstances. The specimens were found in wet gravel on the side of a stony stream together with Limnebius dioscoridus Jäch & Delgado, 2012 . The stones were submerged in water and overgrown by a thin layer of algae (J. Hájek, pers. comm.).

Notes on the taxonomy of the genus Hemisphaera . The genus Hemisphaera Pandellé, 1876 currently contains five species, of which three ( H. seriatopunctata , H. miltiadis and H. guignoti ) occur in the Mediterranean and two are African ( H. lima is known from Tanzania and H. liliputana from Madagascar). Additional potentially undescribed taxa are known from Africa, Europe and southern India (M. Fikáček & J. Delgado, unpubl. data). For this study we have examined the type and additional material of four described species, which were found to slightly differ in the convexity of elytra, extent of pale coloration of pronotum and elytral apices and the coloration of maxillary palpi and in the character of elytral series. They also exhibit large differences in the morphology of the aedeagus and the shape of sternite 9 ( Figs. 36 , 38, 41, 43 ). The genitalia and sternite 9 of H. seriatopunctata are not illustrated here (see CASTRO & DELGADO (1997) for aedeagus illustration), but are extremely similar to those of H. miltiadis (including the presence of the X-shaped thickening on the median lobe and long median projection of sternite 9) and the status of both latter species hence requires revisional study.

Laccobiini

Figures

Figs. 23–25. Hemisphaera socotrana sp. nov. 23–24 – general habitus (23 – dorsal view, 24 – lateral view); 25 – type locality (stream in wadi Ayhaft).

Figs. 26–33. Hemisphaera socotrana sp. nov. 26 – head, ventral view; 27 – detail of mentum; 28 – meso- and metaventrite; 29 – antenna; 30 – prosternum; 31 – head, dorsal view; 32 – lateral portion of pronotum; 33 – abdomen.

Figs. 34–36. Male genitalia of the holotype of Hemisphaera socotrana sp. nov.34–35 – aedeagus (34 – general view; 35 – detail of parameres and median lobe); 36 – sternite 9.

Figs. 37–43. Male genitalia of the Hemisphaera species (37, 39–40, 42 – aedeagus; 38, 41, 43 – sternite 9). 37–38 – H. guignoti Schaefer, 1975 (Algeria, ‘Philippeville’ [= Skikda], coll. NMPC); 39–41 – H. miltiadis Sahlberg, 1908 (39 – paratype, Lesbos, coll. IRSNB; 40–41 – Turkey, Izmir, coll. IRSNB); 41–43 – H. lima Orchymont, 1941 (paratype, Tanzania, Ukerewe, Victoria Nyanza, coll. IRSNB).