Georissus (Neogeorissus) smetanai, Fikáček, Martin, 2012

Fikáček, Martin, 2012, A new species of leaf-litter inhabiting Georissus from Borneo (Coleoptera: Hydrophiloidea: Georissidae), Zootaxa 3316, pp. 63-68 : 63-66

Georissus (Neogeorissus) smetanai sp. nov.

Figs 1-6

Type locality. Malaysia, Sabah province, Mt. Kinabalu National Park, Layang Layang env., 2600 m a.s.l. [the village is not mentioned on the locality labels, but the locality was specified on my request by I. Löbl].

Type material. HOLOTYPE: male ( MNHG): “ SABAH / Mt. Kinabalu / 2600 m, 2.V.1987 / Burckhardt – Löbl // 11a [on the opposite side of the label]”. PARATYPES: 121 spec. ( MNHG, NMPC, BMNH, KSEM, NHMW, ZMUC): same label data as the holotype; 21 spec. ( MNHG, NMPC): SABAH / Mt. Kinabalu / 2600 m, 1.V.1987 / Burckhardt – Löbl // 10a [on the opposite side of the label]; 1 male, 6 spec. ( MNHG, NMPC): “BOR- NEO: SABAH Mt. / Kinabalu Nat. Pk. / Layang Layang / 2160m, 2.V. [19]87 / A. Smetana”; 1 male, 1 female, 45 spec. ( MNHG, NMPC): “BORNEO: SABAH Mt. / Kinabalu N. P. Sum- / mit Tr. Pondok Lo- / wii 2300-2400m / 28.IV. [19]87 A. Smetana”.

Diagnosis. By the arrangement of the protuberances and depressions on the pronotum, G. smetanai sp. nov. belongs to the G. laesicollis species group defined by Delève (1967a): the pronotum bears a large rhomboid central depression, a pair of oval depression posterolaterally of the central depression, and a protuberance on each side laterally of the oval depressions. It may be easily distinguished from all remaining Oriental taxa of the species group by the combination of following characters: pronotum without large lateral projections; elytra with elevated suture and intervals 2, 4 and 6; intervals 1, 3 and 5 flat, largely eliminated by coarse and densely arranged punctation; and ridge on interval 2 with tubercles situated basally and at midlength, hence appearing angular in lateral view. When the aedeagus of G. smetanai sp. nov. is compared with other species of the G. laesicollis group (at least those with known male, as few species are described according to females only), it resembles G. calculus Delève, 1969 and G. inflatus Delève, 1972 by the continually arcuate lateral margins of parameres and phallobase ca. as long as the parameres; both latter species may be easily distinguished by all intervals being of the same height (in contrast to elevated alternate internals in G. smetanai sp. nov.).

Description. Body widely oval, rather highly convex. Body length 1.20–1.70 mm (holotype 1.45 mm), width of head 0.40–0.60 mm (holotype 0.55 mm), maximum width of pronotum 0.65–0.80 mm (holotype 0.70 mm), maximum width of elytra 0.85–1.00 mm (holotype 0.95 mm). Coloration of elytra and pronotum reddish brown to dark brown, anterior portion of pronotum slightly paler, head dark brown.

Head. Clypeus with narrow depressed anterior portion divided from posterior portion by low ridges, bearing weak and sparse granulation. Posterior portion subdivided by three longitudinal ridges into “cells”. Frons with a deep rhomboid central depression divided from lateral portions by high ridges; lateral portions further subdivided by two longitudinal ridges on each side. Eyes small, narrowly elongate in lateral view.

Prothorax. Pronotum 1.2× as wide as long, with maximum width at anterior third; lateral portions only very slightly projecting laterad. Anterior portion with two closely situated submedian ridges delimiting median groove, each side laterally of the ridges with two low and wide bulges. Central portion of pronotum with large and deep rhomboid depression delimited by high ridges, lateral angles of the central depression projecting to high protuberances; posterolaterally of the central depression with one oval depression on each side, laterally of these depressions with a small protuberance bearing few setiferous granules. Posterolateral pits large and conspicuous. Ventral morphology of the prothorax corresponding with G. crenulatus .

Mesothorax. Elytra combined as wide as long, 1.7× as long as pronotum; base of elytra ca. as wide as maximum width of pronotum, maximum width of elytra in anterior quarter, median portion of elytra slightly bulging posteriad. Elytral suture and intervals 2, 4 and 6, 7, and 8 elevated into sharp narrow strongly denticulate ridges, ridge on interval 2 projecting into slightly higher bulge basally and at midlength, hence slightly angular in lateral view; intervals 1, 3, and 5 not elevated, largely obsolete among extremely coarse and very closely aggregated punctation; punctation retaining its serial arrangement between suture and first elytral ridge, serial arrangement largely eliminated between more lateral ridges. Lateral portion projecting into small wing-like denticulate projections in anterior quarter. Median pentagonal protuberance of mesoventrite with two large circular pits next to each other.

Metathorax. Metathoracic wings absent in all specimens examined for this character (n=6). Metaventrite ca. as long as mesoventrite.

Abdomen with lateral margins of ventrites 1 and 2 strongly narrowing posteriad. Ventrites 1 and 2 bearing scattered setiferous tubercles; ventrites 1 and 2 without any large bulges.

Aedeagus 0.40–0.45 mm long (holotype 0.4 mm). Parameres ca. as long as phallobase, when combined their base slightly narrower than phallobase; lateral margins of parameres nearly parallel-sided in basal 0.8, arcuately bent inward apically, inner margins straight, well sclerotized. Median lobe narrowly triangular, gonopore situated subapically, struts ca. 0.4× as long as apical portion of median lobe. Phallobase slightly widening posteriad, widely open posteriorly, basal foramen occupying posterior 0.4 of the phallobase.

Etymology. This species is dedicated to one of its collectors, Aleš Smetana, on the occasion of his 80th birthday, and as my thanks for his kind support of my studies of the Hydrophiloidea.

Biology. All known specimens of G. smetanai sp. nov. were sifted from cloud forest leaf litter under the following circumstances (I. Löbl & A. Smetana, pers. comm., ordered according to collecting date): (i) 28.iv.1987, lgt. Smetana: rather wet moss forest on a steep slope, sifting of fallen leaves with detritus mainly in small forest floor depressions, sometimes including the root system of the vegetation; (ii) 1.v.1987, lgt. Burckhard & Löbl: moist gully below Layang Layang, sifted cloud forest floor litter; (iii) 2.v.1987, lgt. Burckhard & Löbl: proximity of Layang Layang, sifted moss and moist leaf litter in cloud forest; (iv) 2.v.1987, lgt. Smetana: sifting various debris, leaf litter and fallen leaves in more or less wet spots in the forest. See below for the discussion on the leaf litter association of this species and its comparison with other Georissus species collected under such circumstances.

Distribution. Only known from two areas in Mt. Kinabalu National Park, at elevations between 2300 and 2600 m.

Figures

FIGURES 1 – 6. Georissus smetanai sp. nov. 1 – 2: habitus of the paratype (1: dorsal view, 2: lateral view); 3: aedeagus of the holotype; 4 – 5: sculpture of dorsal surface, paratype (4: head; 5: pronotum); 6: sculpture of the abdominal ventrites, paratype.