Kenyacus angustatus, Kataev, 2019

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 : 485-488

The angustatus group

Diagnosis. Body length 3.0– 3.6 mm. Apex of left mandible acute. Microsculpture on disc of pronotum and elytra transverse. Pronotal base more or less straight; basal angles obtuse or almost right, sharp or rounded at tip, not projecting posteriorly. Elytral striae distinct, slightly impressed either apically or along entire length. Female genitalia relatively small, with almost symmetrical laterotergite and with apical stylomere narrow or markedly widened basally. Median lobe of aedeagus stout, with relatively large basal bulb.

Kenyacus angustatus sp. n.

( Figs 17, 21 , 50a , 52 , 55–65 )

Type material. Holotype: ♂, “ UGANDA: Western Region, Kasese District, 9.5 km NWW Nyakalengija, Rwenzori Mts. National Park, main trail from John Matte Hut to Nyabitaba Hut , 0°21.97’N 29°57.58’E, accuracy 200 m, extent 15 m, h = 2800 m, Hagenia , Hypericum , Rubus , Impatiens , big gaps with bushes and grass, sifting leaf litter [3596] [Garmin 60CSx; WGS84] V.I. Gusarov, 17.viii.2008, U162” ( ZMUN).

Paratypes: 7 ♂♂, 8 ♀♀, same data as holotype ( ZMUN, ZIN); 7 ♂♂, 5 ♀♀, “ UGANDA, Western Region, Kas- ese District, 8 km NWW Nyakalengija, Rwenzori Mts. National Park, trail from Nyabitaba Hut to Mahoma Lake, 0°21.036’N 29°58.100’E, accuracy 7 m, extent 10 m, h = 2957 m, Podocarpus , Erica , bamboo, on the ridge, sifting leaf litter [3601] [Garmin 60CSx; WGS84] V.I. Gusarov 18.viii.2008 U166” ( ZMUN); 9 ♂♂, 10 ♀♀, “ UGANDA, Western Region, Kasese District, 8 km W Nyakalengija, Rwenzori Mts. National Park, trail from Nyabitaba Hut to Mahoma Lake, 0°20.748’N 29°58.085’E, accuracy 6 m, extent 15 m, h = 2988 m, bamboo, Podocarpus , sifting leaf litter [3600] [Garmin 60CSx; WGS84] V.I. Gusarov 18.viii.2008 U165” ( ZMUN, ZIN, cWR); 1 ♂, “ UGANDA, Western Region, Kasese District, 8 km W Nyakalengija, Rwenzori Mts. National Park, Mahoma Lake, 0°20.735’N 29°58.108’E, accuracy 5 m, extent 10 m, h = 2959 m, Hagenia , Podocarpus , bushes, grass, lianas, sifting leaf litter [3598] [Garmin 60CSx; WGS84] V.I. Gusarov 18.viii.2008 U164” ( ZMUN); 1 ♂, 1 ♀, “ UGANDA, Western Region, Kasese District, 10 km NWW Nyakalengija, Rwenzori Mts. National Park, main trail from John Matte Hut to Nyabitaba Hut, 0°22.071’N 29°57.378’E, accuracy 15 m, extent 15 m, h = 2999 m, Hagenia , Hypericum , Rubus , Impatiens , big gaps with bushes and grass, sifting leaf litter [3595] [Garmin 60CSx; WGS84] V.I. Gusarov 17.viii.2008 U161” ( ZMUN).

Description (6 males and 5 females measured). Habitus as in Fig. 52 . Body length 3.1–3.4 mm, width 1.3–1.5 mm.

Colour: Body light brown to brown, dorsal surface slightly shiny, ventral surface slightly paler than dorsal surface; base of mandibles, labrum, clypeus, often also lateral margins of pronotum and elytra, as well as elytral suture and epipleura brownish yellow; palpi, antennae and legs brownish yellow; antennae more or less clearly infuscate from antennomere 2 or 3.

Head: Comparatively large, in males HWmax/PWmax 0.79–0.83 (m = 0.81) and HWmin/PWmax 0.66–0.71 (m = 0.69); in females these indices respectively 0.79–0.83 (m = 0.81), and 0.68–0.72 (m = 0.71). Eyes with large facets, slightly convex, HWmax/HWmin 1.16–1.20 (m = 1.17) in males and 1.11–1.18 (m = 1.15) in females, separated from buccal fissure at distance of slightly less than width of antennomere 1. Tempora short, at most about quarter as long as eye, flat and oblique. Frons and vertex convex. Fronto-clypeal suture distinct, impressed, usually as deep as frontal furrows. Supraorbital setigerous pore located 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 more or less straight apical margin between them. Mentum and submentum fused, submentum with two setae 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 distinct isodiametric meshes on clypeus and of mixture of finer isodiametric and slightly transverse meshes on frons and vertex. Antennae comparatively long, surpassing basal edge of pronotum approximately by apical antennomere, with antennomeres 7–9 slightly longer than wide; in female antennae slightly shorter than in male, with shorter antennomeres.

Pronotum: Comparatively narrow, PWmax/PL 1.19–1.37 (m = 1.28), widest at the end of anterior third, markedly narrowed posteriorly, PWmax/PWmin 1.30–1.41 (m = 1.34); lateral seta inserted before widest point, approximately at the end of anterior quarter. Sides rounded anteriorly, usually straightly, more rarely very slightly sinuately converging from widest point to basal angles, without distinct border. Apical margin very shallowly arcuately emarginate, occasionally 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 slightly oblique at basal angles; both apical and basal margins not bordered. Basal angles obtuse, blunted or very narrowly rounded at tip, not projecting posteriorly. Disc moderately convex, strongly sloped to apical angles and flattened latero-basally. Lateral furrows very narrow, slightly widened in basal third or quarter, reaching basal angles and very slightly prolonged on basal margin. Basal foveae very shallow, oval, not clearly delimited, in most specimens isolated from basal pronotal edge and lateral furrows. Surface of pronotum impunctate. Anterior transverse depression variable, usually not distinctly delimited. Median line very thin, superficial, often indistinct at apical and basal margins of pronotum. Microsculpture present throughout, consisting of large isodiametric or slightly transverse meshes ( Fig. 17 ).

Elytra: Oval, widest at middle or just behind it, in males EL/EW 1.39–1.48 (m = 1.42), EL/PL 2.53–2.58 (m = 2.55), and EW/PWmax 1.37–1.45 (m = 1.41); in females these indices respectively 1.36–1.44 (m = 1.42), 2.46–2.69 (m = 2.55), and 1.41–1.46 (m = 1.43). Humeri prominent, widely 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 very thin, slightly crenulate, superficial, at most slightly impressed apically, their bases somewhat indistinct. Parascutellar setigerous pore present, large. Parascutellar striole more or less highly reduced, often absent. Intervals flat or very slightly convex, almost not narrowed posteriorly; intervals 2 and 3 almost parallel-sided or slightly widened at apex; interval 3 in most specimens without discal pore; very rarely a discal pore present in apical third, mostly on one side. Microsculpture distinct throughout, consisting of slightly transverse meshes ( Fig. 21 ).

Ventral surface of thorax and abdomen: Prosternum with 1–5 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, VI much more sparsely than VII, occasionally only with few short setae; apex of last visible sternite with two pairs of marginal setae in both sexes, rounded or 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 mesotarso- meres 2–4 of male slightly dilated (mesotarsi very faintly) and with biseriately arranged long adhesive scales ventrally; mesotarsomere 4 rather deeply emarginate.

Male genitalia: Median lobe ( Figs 55, 57, 58, 60, 61 ) stout, with large basal bulb, in dorsal view markedly narrowed in apical portion, in lateral view arcuate, more strongly bent at or before middle, with almost straight ventral margin in apical portion. Terminal lamella short, straight, without apical capitulum; in dorso-caudal view narrowly rounded at apex ( Figs 56, 59 ). Internal sac without any sclerotic elements.

Female genitalia: Very small ( Figs 62, 65 ); laterotergite (hemisternite) relatively small and wide, slightly asymmetrical, membranous apically, without setae and spines. Basal stylomere elongate, usually with few shot setae apically. Apical stylomere noticeably shorter than basal stylomere, with short thick seta at ventral edge of outer margin, in ventral view markedly curved, with wide base; in lateral view evenly narrowed to acute apex ( Figs 62, 64 ).

Etymology. The specific name is a Latin adjective meaning “narrow, constrict” and referring to the pronotum of the new species narrowed basally.

Distribution ( Fig. 50a ). This new species is found in vicinity of the Mahoma Lake, and in the Bujuku valley at altitudes of 2800–2999 m in the south-eastern part of the Rwenzori Mountains, where it occurs sympatrically with K. ruwenzorii and K. similis sp. n.

Bionomics. According to the label data, beetles were collected by sifting leaf litter in forest with Podocarpus , Erica , Hagenia , Hypericum and bamboo ( Figs 91 , 92 ).

Comparison. This new species is well recognized from all other congeners from the Rwenzori Mountains by combination of the following distinctive characters: small body size (3.1–3.4 mm); relatively narrow pronotum ( Fig. 52 ) markedly narrowed basally, with basal angles obtuse, clearly blunted or narrowly rounded at tip; pronotal basal margin more or less straight; elytral striae thin, distinct, at most slightly impressed apically; elytral sutural angle clearly blunted or narrowly rounded at tip; apical stylomere in lateral view evenly narrowed to acute apex ( Figs 62, 64 ); and median lobe in lateral view moderately arcuate, more strongly bent at or before middle ( Figs 57, 60, 61 ). In small body size, K. angustatus sp. n. is similar to the sympatric K. similis sp. n. and the allopatric K. pusillus sp. n. and K. ruwenzoricus and markedly differs from other species. Differences between K. angustatus sp. n., K. similis sp. n., K. pusillus sp. n. and K. ruwenzoricus are described below under the latter three species.

Figures

FIGURE 50. Kenyacus, distribution. a, K. angustatus sp. n.; b, K. parvus sp. n.

FIGURE 91. Mahoma lake (ca. 2960 m) near the type locality of K. similis sp. n. Patches of Erica, Hagenia, Podocarpus and bamboo forest, separated by large gaps with bushes and herbaceous vegetation. Habitats of K. ruwenzorii, K. angustatus sp. n. and K. similis sp. n. Photo: Vladimir Gusarov.

FIGURE 92. Bujuku valley between Nyabitaba Hut and John Matte Hut (ca. 2800–2900 m) near the type localities of K. trechoides sp. n., K. angustatus sp. n. and K. pusillus sp. n. Forest patches with Podocarpus, Hagenia and Hypericum separated by large gaps with bushes and herbaceous vegetation. Photo: Vladimir Gusarov.

FIGURES 14–21. Kenyacus, microsculpture (14–17, male pronotal; 18–21, male elytral). 14, 18, K. ruwenzorii (Alluaud, 1917); 15, 19, K. gusarovi sp. n.; 16, 20, K. parvus sp. n.; 17, 21, K. angustatus sp. n. Scale bar = 0.2 mm.

FIGURES 52–54. Kenyacus, habitus (males). 52, K. angustatus sp. n. (paratype, loc. U166); 53, K. similis sp. n. (holotype); 54, K. pusillus sp. n. (holotype). Scale bar = 1.0 mm.

FIGURES 55–81. Kenyacus. 55–65, K. angustatus sp. n. (55–57, paratype, loc. U166; 58–60, holotype; 61, paratype, loc. U162; 62, 63, same, loc. U166; 64, 65, same, loc. U162); 66–73, K. similis sp. n. (66–68, holotype; 69, 70, paratype, loc. U164; 71–73, same, loc. U165); 74–81, K. pusillus sp. n. (74–76, holotype; 77, 78, paratype, loc. U133; 79–81, same, loc. U123). 55, 58, 66, 76, median lobe, dorsal view; 57, 60, 61, 68, 73, 74, same, lateral view; 56, 59, 67, 75, apex of median lobe, dorso-caudal view; 62, 64, 69, 71, 77, 79, 80, stylus, lateral view; 63, 65, 70, 72, 78, 81, laterotergite and stylus, ventral view. Scale bar = 0.5 mm.