Kenyacus Alluaud, 1917

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 : 464-466

The genus Kenyacus Alluaud, 1917

Kenyacus Alluaud, 1917: 96 (as genus). Type species: Kenyacus hypsibius Alluaud, 1917 , designated by Basilewsky, 1951: 223.

Tropicoritus Alluaud, 1917: 95 (as genus), syn. n. Type species: Tropicoritus ruwenzorii Alluaud, 1917 , by monotypy.

Recognition. Within Stenolophina , adults of Kenyacus are recognizable by combination of the following distinctive characters: mentum without median tooth, fused with submentum, ligular sclerite with four preapical setae, supraorbital pore situated far from supraorbital furrow, posterior group of elytral marginal umbilicate series not clearly divided in two separate subgroups, and metepisterna short, at most as long as wide.

Description. Small: body length 2.4–6.0 mm. Apterous. Body light brown to blackish brown, dorsum not iridescent and without metallic lustre. Head large, with wide neck. Antennae short or moderately long, with rather wide and short antennomeres, densely pubescent beginning from antennomere 3; pubescence comparatively long; antennomere 2 sparsely pubescent and pubescence mostly restricted to apical half of antennomere. Eyes slightly or moderately convex, separated from buccal fissure by distance. Supraorbital pore situated far from supraorbital furrow. Fronto-clypeal suture superficial or somewhat impressed. Frontal furrows distinct, deepened. Mentum without median tooth, fused with submentum at least laterally, with narrow epilobes. Ligular sclerite narrowed apically, with two ventral and two dorsal preapical setae. Paraglossae glabrous, narrow, much longer than ligular sclerite and separated from it by deep notch. Penultimate labial palpomere with two setae at anterior margin and with one preapical seta ventrally. Pronotal basal angles rounded or sharp. Elytra oval, moderately short or elongate, with comparatively short, occasionally indistinct parascutellar striole, and with or without one discal pore on interval 3. Elytral marginal umbilicate series consisting of six (5+1) setigerous pores in anterior group and of eight setigerous pores in posterior group; posterior group not divided in two separate subgroups. Parascutellar setigerous pore markedly removed from elytral basal border. Prosternum usually with several erect setae medially, rarely glabrous. Prosternal process without apical setae. Metepisterna short, at most as long as wide. Abdomen of male without basal setose fovea. Abdominal sternites (ventrites) largely glabrous, only with obligatory setae, but in many species one to three last visible sternites sparsely setose. Last visible (VII) sternite with a preapical marginal angular projection on each side, and with one or two pairs of marginal setae in male and with two pairs of such setae in female. Protarsomere 1 bilobed. Tarsomere 5 with or without a pair of latero-ventral setae. Pro- and mesotarsi in male moderately or only slightly dilated and with biseriately arranged adhesive scales ventrally, but in many species adhesive vestiture on mesotarsi more or less reduced. Median lobe of aedeagus with or without spines in internal sac.

These characters shared by all the species of Kenyacus are not repeated in descriptions of the species below, which only include characters sufficient for discrimination.

Comparison. Based on mentum without median tooth and elytral posterior group of marginal umbilicate setal series not divided into two markedly separated subgroups, the genus Kenyacus belongs to the Acupalpi genus group within Stenolophina , which also includes the genera Acupalpus Latreille, 1829 , Philodes LeConte, 1861 , Anthracus Motschulsky, 1850 , Uenanthracus Kasahara, 1994 , and Cyptomicrus Vinson, 1939 . Within the Acupalpi genus group, Kenyacus is most similar and apparently most closely related to Anthracus sensu Jaeger, 2012 . Both genera share several distinctive characters, including ligular sclerite with four setae and mentum fused with submentum at least laterally. Like in Anthracus , in many species of Kenyacus prosternum is covered with long erect setae and tarsomere 5 lacks ventrolateral setae. Jaeger (2012) treated ligular sclerite with four setae as an autapomorphic character for the genus Anthracus , including the annamensis group; the latter taxon was formerly considered within the genus Acupalpus . In my opinion, this character should be treated as synapomorphy for the monophyletic group comprising the genera Anthracus sensu Jaeger, 2012 and Kenyacus . Among other Stenolophina , four setae on ligular sclerite occur only in Parabradycellus Ito, 2003 , but this feature arose in this genus independently from Anthracus and Kenyacus , because Parabradycellus having mentum with a median tooth and abdomen of male with a basal setose fovea belongs to another genus group, namely the Bradycelli group. Kenyacus differs from Anthracus in the following, apparently apomorphic characters: supraorbital pore removed from supraorbital furrow; eyes smaller and less convex, separated from buccal fissure by distance; parascutellar setigerous pore markedly removed from elytral basal border; prosternal process without apical setae; metepisterna short, wider than long or at least as long as wide; and abdominal sternites more sparsely pubescent. Unlike apterous Kenyacus , most species of Anthracus have developed hind wings and capable of flying.

The genus Kenyacus should be treated as a specialized derivate of Anthracus sensu Jaeger, 2012 adapted to the mountainous regions of East Africa. The genus Anthracus is distributed mainly over the plains in the Holarctic, Ethiopian, Oriental and Australian regions and, according to Jaeger (2012, 2016), comprises several rather distinct species groups including the consputus group (= Anthracus s. str.) from the West Palaearctic, the overlaeti group from the Ethiopian region, the annamensis group from the Oriental and Australian regions, and the angusticollis group mainly from the Ethiopian and Oriental regions (some species are still not assigned to any group). The angusticollis group is most specialized, since its members are characterized by two apomorphic character states (pronotal median line deeply impressed and markedly broadened, and elytral lateral margin serrate) which are unique not only within the genus and related genera, but obviously also within the subtribe Stenolophina ( Jaeger, 2016) . Therefore, in combination of the characters, Kenyacus is more similar to the less specialized consputus, overlaeti and annamensis groups, especially to the latter group, members of which share with Kenyacus similar habitus with comparatively short antenna and oval elytra as well as less markedly deepened clypeo-ocular furrows and frontoclypeal suture.

Remarks. The genera Tropicoritus and Kenyacus were described in one paper without direct comparison with each other: the former genus for one species from the Rwenzori Mountains and the latter one for two species from Kenya ( Alluaud, 1917). According to Basilewsky (1951), both genera belong to the Bradycellina (= Bradycelli genus group) and Tropicoritus differs from Kenyacus in having mentum with median tooth and pronotal basal angles projecting posteriorly above elytral base. Although Alluaud (1917) in the original description also stated that Tropicoritus has mentum with a median tooth, re-examination of the holotype of the single species included in this taxon revealed that this character was indicated erroneously and in fact, the mentum in Tropicoritus lacks median tooth as in the genus Kenyacus . Since the basal pronotal angles in Kenyacus are rather variable (rounded or somewhat prominent as, for example, in K. acrobius and K. kinangopius , and it can be found all transitions in the species from the Rwenzoris), Tropicoritus and Kenyacus are treated here as synonyms. The selection of the valid name for this genus between Kenyacus and Tropicoritus , which were described in one paper, was made for benefit of the former name, as much better-known, in the interest of nomenclatorial stability. However, all the species of Kenyacus from the Rwenzori Mountains considered in this paper seem to represent a monophyletic group because they differ from other examined species of this genus in the combination of the following characters: tarsomere 5 without lateroventral setae, last visible abdominal sternite in both sexes with two pairs of setae, and median lobe of aedeagus with shorter terminal lamella and without spines in internal sac. In addition, pronotum of the species inhabiting the Rwenzori Mountains is usually with sharper basal angles and with sides not rounded. Further research should show if this group warrants subgeneric status. Relationships of this group with congeners from other regions are still obscure and can be established only after the complete revision of the genus.

The species treated in this paper, like many other Harpalini, demonstrate rather high variability in many morphological characters and are difficult taxonomically. In most cases, for their delimitation the examination of both male and female genitalia is needed. The shapes of the female laterotergite and apical stylomere are usually as reliable distinctive characters for discrimination of most species as the structure of the median lobe of the aedeagus. The body size and shape of pronotum are also very useful for species identification.Although true interrelationships among species remain poorly understood, based on the combinations of the morphological characters, the species of Kenyacus known from the Rwenzori Mountains can be preliminarily divided in the following groups that can also be in part distinguished by body size: 1) K. ruwenzorii ; 2) K. gusarovi s p. n.; 3) K. parvus sp. n., K. berndi sp. n., and K. trechoides sp. n.; 4) K. angustatus sp. n., K. similis sp. n., and K. pusillus sp. n.; and 5) K. ruwenzoricus . Diagnoses of these groups are provided below. Morphological basis for this grouping is partly reflected also in the key. The true relationships must await further studies, including molecular analysis.