Somoplatus Dejean, 1829

Schüle, Peter, 2009, Notes on the genus Somoplatus Dejean, 1829 (Coleoptera: Carabidae), with descriptions of five new species, African Invertebrates 50 (2), pp. 461-461 : 462-466

Genus Somoplatus Dejean, 1829

Somoplatus: Dejean 1829: 3 , 15

(Type species: Somoplatus substriatus Dejean, 1829 , by monotypy).

Paralophidius: Basilewsky 1986: 252 . Syn. n.

The genus Somoplatus belongs to the tribe Cyclosomini Castelnau, 1834 and subtribe Masoreina Chaudoir, 1870 . All known species are fairly small (2.9–8 mm), coloured reddish brown to yellowish.

Head with large protruding eyes, two supraorbital setae; labrum transversal, bearing six setae, apical margin straight or sinuous. Proportions of antennomeres vary within the genus: short (as long as wide) to long (2.5× longer than wide). Scape glabrous with one long and a few smaller subapical setae; antennomeres 2 and 3 glabrous except a few subapical setae; antennomeres 4–11 pubescent, more or less filiform with median glabrous, glossy band on inner and outer side. Mentum with distinct tooth, bisetose. Palpi glabrous, except penultimate palpomere of labial palpi with 2 subapical setae. Terminal palpomeres fusiform, outer margin slightly more curved than inner margin.

Pronotum short and wide, lateral impression inconsistent: missing, indistinct, visible in basal portions only or distinct and widened from apex to base. Lateral marginal furrow narrow; lateral margins rounded or slightly sinuate in basal half, bisetose; anterior marginal seta on anterior third, posterior marginal seta on basal angle; apex concave, apical angles protruding but rounded. Base undulate, with middle part slightly convex. Basal angles fairly distinct to completely rounded. Median line distinct. Surface of pronotum with fine microreticulation consisting of pattern of dense transversal meshes, glabrous, with extremely fine microsetae or with fine regularly seta-bearing punctation.

Elytra short and wide, oviform, subparallel-sided in the middle. Striae very shallow or absent, surface with traces of microsetae or fairly long pubescence. Microsculpture consisting of transversal, very narrow meshes. Apical truncation very indistinct: apical margin rounded to very indistinctly sinuate, sutural angle rounded. Umbilicate series of marginal setae consisting of 6 subhumeral, 3 intercalar, 4 subapical setae and one apical seta.

Lower surface finely pubescent or partly pubescent, pubescence short to fairly long. Prosternal process bearing long distant setae (4–12).

Legs short, outer margin of tibiae with a row of long, straight thorns. Hind tibiae with two thorns apically, inner thorn longer than half of first tarsomere. Upper side of tarsi glabrous or with sparse pubescence.

Key to species of the genus Somoplatus

1 (26) Surface of head plain or with macrosculpture of head shallow consisting of indistinct wrinkles on lateral portions of vertex. Frontal sulci indistinct, subcircular or elongate, dimple-shaped.

2 (5) Dorsal surface of pronotum glabrous or with traces of extremely fine microsetae (readily obvious under 100× magnification). Elytra dorsally glabrous or with extremely fine microsetae and longer pubescence restricted to lateral portions.

3 (4) Body smaller (3.5–3.8 mm), hind angles of pronotum blunt but not rounded ....................................................................................... S. genierorum sp. n.

4 (3) Body larger (4.5–5.1 mm), hind angles of pronotum rounded ........................ ................................................................................................ S. depilis sp. n.

5 (2) Pronotal surface pubescent, pubescence composed of fairly long semidistant setae.

6 (7) Elytral surface glabrous except for extremely fine pubescence composed of microsetae, pronotal surface pubescent with pubescence composed of fairly long setae ............................................................................. S. pilicollis sp. n.

7 (6) Elytral surface with dense pubescence, pronotum pubescent or partly pubescent.

8 (19) Body smaller than 5.5 mm.

13 (14) Median portions of two basal tarsomeres of hind tarsi dorsally pubescent ..... ............................................................................................ S. morettoi sp. n.

14 (13) Tarsomeres of hind tarsi dorsally lacking pubescence except a few apical setae.

15 (16) Antennae moniliform (antennomeres max. 1.2× longer than wide), body small (2.9–4.0 mm) ...................................................... S. fulvus Mulsant & Godart

16 (15) Antennomeres not moniliform, at least 1.5× longer than wide, body small to medium sized (4.0– 5.1 mm).

17 (18) Stylomere 2 short, apically hook-like arcuate ( Fig. 27 ), apex of aedeagus short ............................................................................. S. septentrionalis Burgeon

18 (17) Stylomere 2 long, regularly arcuate ( Fig. 28 ), apex of aedeagus long ( Fig. 21 ) ........................................................................................... S. ivoirensis sp. n.

19 (8) Body longer than 6.0 mm.

20 (21) Antennae longer, 3 apical antennomeres projecting over the base of pronotum ..................................................................................... S. girardi Basilewsky [Specimens from Ivory Coast with reduced macrosculpture of head consisting of indistinct, oblique wrinkles on anterior portions of head.]

21 (20) Antennae shorter, maximum 1 or 2 apical antennomeres projecting over base of pronotum.

22 (25) Body broader, less elongate. Pronotum proportionally wider (1.60–1.85× wider than long) with lateral margins convex, widest in the middle or in basal half, not sinuate towards blunt or rounded hind angles. Antennae longer, 1 or 2 apical antennomeres projecting over base of pronotum.

23 (24) Pronotum more transverse (1.65–1.85× wider than long), widest near base, base wider than apical margin.Elytra short, more convex, lateral margins arcuate (1.36–1.40× longer than wide). Apex of aedeagus straight ............................. ............................................................................... S. amplicollis Basilewsky

24 (23) Pronotum less transverse (1.60–1.70× wider than long), widest in the middle, base not wider than apical margin. Elytra longer, lateral margins subparallel (1.50–1.63× longer than wide). Apex of aedeagus bent upwards .................... ................................................................................... S. substriatus (Dejean)

25 (22) Body narrower, more elongate. Pronotum proportionally narrower (1.42–1.47× wider than long). Lateral margins subparallel, not arcuate, not widened near the middle or in basal half, slightly sinuate towards rectangular hind angles. Antennae short, not reaching base of pronotum. Surface of pronotum glabrous ...................................................................................... S. elongatus Burgeon

26 (1) Macrosculpture of head surface in anterior portions consists of distinct wrinkles or carinae between frons and inner margins of eyes. Frontal sulci distinct as arcuate grooves.

27 (30) Position of lateral seta of stylomere 2 (terminal sclerite of the ovipositor) near middle.

28 (29) Antennae short, moniliform, maximum 2 apical antennomeres projecting over base of pronotum, central antennomeres slightly longer than wide. Pronotum more transverse (1.90–2.0× wider than long), lateral margins less regularly convex, pronotal base wider than apex. Surface of elytra glossy .................... .................................................................................... S. brevicollis (Dejean)

29 (28) Antennae longer, more filiform, nearly 3 apical antennomeres projecting over base of pronotum, central antennomeres distinctly longer than wide. Pronotum less transverse (1.80–1.90× wider than long), lateral margins regularely convex, pronotal base wider than apex. Surface of elytra dull...................................... ..................................................................................... S. girardi Basilewsky

30 (27) Position of lateral seta of stylomere 2 (terminal sclerite of the ovipositor) near base.

31 (32) Antennae longer, more filiform, 3 apical antennomeres projecting over base of pronotum. Pronotum more transverse (1.73–1.83× wider than long). Elytra narrower and more elongated (1.28–1.36× longer than wide), lateral margins subparallel ............................................................... S. simillimus Basilewsky

32 (31) Antennae shorter, less filiform, less than 3 apical antennomeres projecting over base of pronotum. Pronotum less transverse (1.67–1.70× wider than long). Elytra proportionaly broader and more stout (1.22–1.27× longer than wide), lateral margins more arcuate ................................... S. guineensis Basilewsky

Figures

Figs 24–30. Stylomere 2 of Somoplatus spp. ^: (24) S. depilis sp. n., paratype, Ivory Coast, Comoé National Park (PSC); (25) S. pilicollis sp. n., paratype, Ivory Coast, Comoé National Park (PSC); (26) S. fulvus, Ivory Coast, Comoé National Park (PSC); (27) S. septentrionalis, Ivory Coast, Comoé National Park (PSC); (28) S. ivoirensis sp. n., paratype; (29) S. girardi, Ivory Coast, Comoé National Park (PSC); (30) S. genierorum sp. n., paratype, Burkina Faso, Forêt de Nazinga. Scale bar = 0.5 mm in Figs 24, 25, 28–30; 2 mm in Figs 26, 27.

Figs 17–23. Aedeagi of Somoplatus spp.: (17) S. depilis sp. n., holotype; (18) S. pilicollis sp. n., holotype; (19) S. morettoi sp. n., holotype; (20) S. fulvus (after Basilewsky 1986); (21) S. ivoirensis sp. n., holotype; (22) S. girardi, Ivory Coast, Comoé National Park (MRAC); (23) S. genierorum sp. n., holotype. Scale bar = 0.5 mm.