Kenyacus ruwenzoricus Basilewsky, 1955

Kataev, Boris M., 2019, A review of the Afrotropical genus Kenyacus (Coleoptera: Carabidae: Harpalini) from the Rwenzori Mountains, with description of seven new species, Zootaxa 4679 (3), pp. 463-498 : 492-497

Kenyacus ruwenzoricus Basilewsky, 1955

( Figs 83–90 )

Kenyacus ruwenzoricus Basilewsky, 1955: 111 .

Type material examined. Holotype: ♂, labelled “ Coll. Mus. Congo / Uganda: E. Ruwenzori, / ruiss. Kaliba , 2245 m. / R.P.M.J. Celis 25–I–54 ”, “Dans terreau de bambous”, “ HOLOTYPUS ”, and “ Kenyacus ruwenzoricus n. sp. P. Basilewsky det., 1955” ( MRAC) ( Fig. 84 ).

Paratypes: 3 ♂♂, same data as holotype, but labelled as “ PARATYPUS ” and without determination label ( MRAC) ; 1 ♀, “ Coll. Mus. Congo / Uganda: E. Ruwenzori, / Mukasabu / 2440 m. (for. bamb.) / R.P.M.J. Celis 18–I–54 ”, “Dans terreau de bambous”, and “ PARATYPUS ” ( MRAC) .

Re-description (4 males and 1 female measured). Habitus as in Figs 83 and 85 . Body length 3.1–3.8 mm, width 1.4–1.7 mm.

Colour: Body light brown to brown, elytra, occasionally only in apical portion, in some specimens darker than head and pronotum; dorsal surface slightly shiny; base of mandibles, labrum, clypeus, margins of pronotum and elytra, as well as elytral suture, mentum, epipleura of pronotum and elytra usually paler, brownish yellow; palpi, antennae and legs brownish yellow or yellow; antennae slightly infuscate from antennomere 3.

Head: Comparatively large, in males HWmax/PWmax 0.71–0.77 (m = 0.75), HWmin/PWmax 0.63–0.68 (m = 0.66); in female these indices respectively 0.77 and 0.66. Eyes with large facets, slightly convex, in males HWmax/HWmin 1.13–1.16 (m = 1.14) and in female 1.17, separated from buccal fissure at distance of slightly less than width of antennomere 1. Tempora absent or short, at most about one-fifths as long as eye, flat and oblique. Frons and vertex convex. Fronto-clypeal suture distinct, impressed, as deep as frontal furrows. Supraorbital setigerous pore located at or just behind level of posterior margin of eye, removed from supraorbital furrow at a distance of length of antennomere 2. Labrum almost straight anteriorly. Clypeus with slightly prominent apical angles and with more or less straight apical margin between them. Mentum and submentum fused, submentum with one long seta on each side. Mandibles medium-sized; left mandible evenly bent in apical portion, with acute apex. Dorsal microsculpture in both sexes present throughout, consisting of more or less isodiametric meshes, very distinct on clypeus and areas behind eyes and much finer on frons and vertex. Antennae comparatively long, in both sexes slightly surpassing basal edge of pronotum, with antennomeres 7–9 slightly longer than wide; in female antennae slightly shorter than in male, with shorter antennomeres.

Pronotum: Slightly transverse, PWmax/PL 1.31–1.39 (m = 1.35), widest at the end of anterior third, markedly narrowed posteriorly, PWmax/PWmin 1.34–1.43 (m = 1.38); lateral seta inserted slightly before widest point. Sides rounded anteriorly, roundly or almost straightly converging from widest point to basal angles, without distinct border. Apical margin very shallowly emarginate, almost straight medially; apical angles slightly projecting ahead, acute, blunted at tip. Basal margin slightly narrower than apical margin and noticeably narrower than elytral base, almost straight or very shallowly concave medially; both apical and basal margins not bordered. Basal angles either obtuse, blunted at tip, or more or less widely rounded, not projecting posteriorly. Disc moderately convex, strongly sloped to apical angles and flattened latero-basally. Lateral furrows very narrow, usually slightly widened in basal half, reaching basal margin. Basal foveae extremely shallow, oval, not clearly delimited. Surface of pronotum impunctate. Anterior transverse depression shallow, not distinctly delimited, or absent. Median line very thin, superficial, often indistinct at apical and basal margins of pronotum. Microsculpture present throughout, consisting of mixture of more or less isodiametric (mostly along margins) and slightly transverse meshes.

Elytra: Oval, evenly rounded at sides, widest just behind middle, in males EL/EW 1.39–1.40 (m = 1.40), EL/PL 2.54–2.76 (m = 2.67), EW/PWmax 1.37–1.47 (m = 1.42); in female these indices respectively 1.40, 2.67 and 1.36. Humeri slightly prominent, evenly rounded. Preapical sinuation very shallow, often indistinct, in most specimens sides in apical fifth rather sharply curved inside and then almost straightly converging to apex. Sutural angle in both sexes blunted or narrowly rounded at tip. Basal edge slightly sinuate or almost straight, widely arcuately curving inside humerus up to lateral margin. Lateral gutter narrow along entire length. Elytral disc convex in lateral and caudal views. Striae extremely thin, very superficial, slightly crenulate, in basal half partly indistinct. Parascutellar setigerous pore present, larger. Parascutellar striole more or less highly reduced, occasionally its apex connected with stria 1. Intervals absolutely flat, slightly narrowed posteriorly; intervals 2 and 3 often more or less parallel-sided at apex; interval 3 without discal pore. Microsculpture present throughout, consisting of wide, slightly transverse meshes.

Ventral surface of thorax and abdomen: Prosternum glabrous or (in female paratype) with few moderately long erect setae medio-apically. Metepisternum slightly wider than long, narrowed posteriorly. Basal abdominal sternites glabrous, two last visible (VI and VII) sternites sparsely pubescent; apex of last visible sternite with two pairs of marginal setae in both sexes, subtruncate at middle.

Legs: Metacoxae without any additional setae. Tarsi glabrous dorsally. Tarsomere 5 without setae ventrally. Meso- and metatarsomeres 1 about as long as meso- and metatarsomeres 2+3, respectively. Pro- and mesotarsomeres 2–4 of male slightly dilated and with biseriately arranged long adhesive scales ventrally; mesotarsomere 4 rather deeply emarginate.

Male genitalia: Median lobe ( Figs 88, 90 ) elongate, evenly arcuate in lateral view, with moderately large basal bulb. Terminal lamella short, without apical capitulum, with apex very slightly curved in dorsal direction; in dorsocaudal view narrowly rounded at apex ( Fig. 89 ). Internal sac without any sclerotic elements.

Female genitalia: Very small ( Figs 86, 87 ); laterotergite (hemisternite) asymmetrical, membranous apically, with basal portion rather long, curved inside, without setae and spines. Basal stylomere elongate, comparatively narrow, with few very short and fine setae apically. Apical stylomere markedly curved, narrow, almost as long as basal stylomere, with short thick seta at ventral edge of outer margin and with narrow base in ventral view; in lateral view evenly narrowed to apex ( Fig. 86 ).

Distribution. This species is known from the northern part of the Rwenzori Mountains (Kaliba brook and Mukasabu), Bundibugyo District, Uganda, at altidudes of 2245–2440 m in the bamboo zone. It is geographically isolated from the other congeners known from the Rwenzori Mountains.

Comparison. This species is similar in size and habitus to K. angustatus sp. n., K. similis sp. n. and K. pusillus sp. n., but markedly differs from them and all other species of Kenyacus known from the Rwenzori Mountains in having pronotal sides in basal half rounded or almost straight, not sinuate ( Figs 83, 85 ), elytral striae extremely thin, very superficial, in basal half partly indistinct, and median lobe of aedeagus slenderer, with apex slightly curved in dorsal direction ( Figs 88 ). The examined specimens of K. ruwenzoricus are also distinguished from other congeners by the presence of only one seta on each side of the submentum. Stability in this character should be checked on additional material.

Remarks. Kenyacus ruwenzoricus was originally described from five specimens collected in the northern part of the Rwenzori Mountains and no additional specimens were found more recently. In the original description, median lobe of this species is illustrated as being with apex straight, not bent at tip in lateral view. Examination of the aedeagus of the holotype only extracted by Pierre Basilewsky revealed that its apex was broken at tip.

Figures

FIGURES 83–85. Kenyacus ruwenzoricus Basilewsky, 1955 (83, 84, holotype, 85, male paratype). 83, 85, habitus; 84, labels.

FIGURES 86–90. Kenyacus ruwenzoricus Basilewsky, 1955 (paratypes). 86, stylus, lateral view; 87, laterotergite and stylus, ventral view; 88, median lobe, lateral view; 90, same, dorsal view; 89, apex of median lobe, dorso-caudal view. Scale bar = 0.5 mm.