Grebennikovius Mlambo, Scholtz & Deschodt, 2019

Mlambo, Sukoluhle, Scholtz, Clarke H. & Deschodt, Christian M., 2019, Grebennikovius, a new genus to accommodate Epactoides basilewskyi (Balthasar, 1960) (Coleoptera: Scarabaeidae: Deltochilini), Zootaxa 4544 (1), pp. 113-118 : 113-116

Grebennikovius Mlambo, Scholtz & Deschodt , new genus ( Figs. 1 , 2 A–C, 3, 4)

Type-species: Phacosoma basilewskyi Balthasar, 1960 , here designated.

http://zoobank.org/ urn:lsid:zoobank.org:act:DE0F195B-0553-45C7-B01C-61C0E0BE77C5

Composition. Grebennikovius basilewskyi ( Balthasar, 1960) , new combination.

Description. Length. 3.0– 3.5 mm. Body small in size, oval shaped in dorsal view; head narrowing strongly anteriorly; elytra narrowing posteriorly but ending blunt and with notch at sutural interval; head and pronotum the same dark brown colour with elytra, pygidium and legs lighter brown.

Head. Clypeus bidentate, denticles triangulate and upturned; sides with very slight notch where clypeo genal suture ends; surface with small, dense rounded punctures; punctures on clypeus smaller than those on genae and frons; punctures with very fine associated setae.

Pronotum. Somewhat convex; densely punctate with small punctures, punctures with associated thin recurved seta; posterior and anterior margins curving anteriorly, almost parallel, anteriomedial area slightly curving anteriorly; lateral margins with obtuse angel about one third from anterior angles; margin at anteriolateral angles appear flattened.

Elytra. Striae with round punctures without setae, punctures closer together than their diameter; interstriae with surface smooth with single or double row of very dense setae each. Small humeral umbone present. Eight striae; stria V with small apical tubercle; stria VIII carinate, sides below carina slanted inward; sutural interval in posterior half appear significantly raised.

Mesometasternum with small punctures, punctures one puncture diameter apart. Mesometasternal suture faint and slightly curved anteriorly, area directly posterior of mesometasternal suture without punctures.

Pygidium. Surface with small punctures with short associated setae; median tubercle present, otherwise flat.

Legs. Front tibia with three denticles on the outer edge. First article of hind tarsi longer than the second.

Aedeagus. Fairly symmetrical, see Figs. 2 A–C. Parameres half the length of the phallobase, apex of the parameres sloping downward towards a flat tip.

Distribution. This monotypic genus is currently only known from the isolated forests in the Uluguru Mountains in Tanzania ( Fig. 3 ).

Etymology. Grebennikovius new genus is named in honour of Vasily Grebennikov, who collected fresh specimens of this new genus for the molecular study by Mlambo et al. (2014). The gender is masculine.

Differential diagnosis. The combination of the hind tarsus with the basal segments approximately twice as long as the next segment and the stria VIII being carinate with the sides below the carina slanting inward will separate this new genus from all other Afrotropical small deltochiline genera. Although the body shape of Grebennikovius new genus and Epactoides are quite similar in appearance, Grebennikovius new genus differs from Epactoides by having a clearly bidentate clypeus while the clypeus of Epactoides is quadridentate ( Figs. 1A, 1B ). Elytra of Grebennikovius new genus are blunt and have a notch at the posterior end whereas that of Epactoides are sharp. Grebennikovius new genus also superficially resembles some species of the southern African genus Epirinus . However, Grebennikovius new genus is generally smaller and it is carinate at the stria VIII with the area below the carina slanted inwardly ( Fig. 1C ). The aedeagus of Epirinus is asymmetrical (see e.g., aedeagus of E. humberti , Fig. 2D ) whereas the aedeagus of this new genus is symmetrical. Like several other deltochiline genera ( Scholtz & Howden 1987), Grebennikovius new genus is monotypic and restricted to a specific forest. It has been collected in leaf litter.

Figures

FIGURE 1. A, Habitus of Grebennikovius basilewskyi (Balthasar, 1960) new combination, paratype male; B, habitus of Epactoides humberti (Paulian, 1975), holotype; C, anterolateral view of elytra of G. basilewskyi showing the carina on the elytral edge. Scale bar = 1 mm for Figs. A, B; Fig. C not to scale.

FIGURE 2. Aedeagus in dorsal (A), right lateral (B) and left lateral (C, D) view. A–C, Grebennikovius basilewskyi (Balthasar, 1960) new combination; D, Epactoides humberti (Paulian, 1975). Scale bar = 0.5 mm.

FIGURE 3. Map showing the location of the Uluguru Mountains (black) in Tanzania. Light grey indicates mountains and dark grey indicates the great lakes (modified from Mlambo et al. 2014).