Microborus angustus Jordal

Jordal, Bjarte H., 2017, Ancient diversity of Afrotropical Microborus: three endemic species - not one widespread, ZooKeys 710, pp. 33-42 : 35

Microborus angustus Jordal sp. n. Figs 3-4, 9-11, 18-20

Type material examined.

Holotype: Cameroon, Mt. Cameroon south slope, 1600m alt., Ficus branch, B. Jordal 28xi-8 [28. Nov. 2007]. ZMBN/ENT_Scol4932. Paratypes (8): same data as HT (ZMBN/ENT_Scol4933-4940). (GIS: 4.12, 9.16). All types deposited in ZMBN.

Diagnosis.

A very elongated, almost black species, with impressed elytral striae and a distinct costate rim along the postero-lateral margin of elytral declivity.

Description

(male and female).Length 1.3-1.5 mm, 2.7-2.8 × longer than wide.Colour dark brown, almost, black, legs and antennae light brown.

Head. Eyes separated above by 1.4 × their width. Frons reticulate and deeply punctured, smooth and shiny at level of antennal insertion, vestiture consisting of a few scant fine setae.

Pronotum smooth, shiny, with densely placed punctures.

Elytra with all striae impressed, punctures deep, subconfluent; interstriae as wide as striae, with very fine irregularly spaced punctures; postero-lateral rim sharply elevated with 3-6 sharp granules. Vestiture consisting of few long, fine, erect golden setae.

Legs. Protibiae with three lateral teeth (embedded denticles), and one additional tooth just above the inner mucro; posterior face smooth.

Ventral vestiture simple, on ventrites very fine, short setae.

Wings typical for weevils, costa with two setae close to each other near base, and one seta two-thirds the distance towards the stigmal patch; anal field missing, posterior margin with long fine setae; stigmal patch with two short, sharp setae, each on a small tubercle.

Proventriculus with apical plate well developed, median suture wide open, sutural teeth long and sharp, apical teeth and marginal bristles missing, closing teeth long and prominent,>10 large femoral teeth.

Male genitalia very simple, spiculum gastrale not present, no distinction between apophyses and aedeagal body, internal sac with granulated surface, tegmen open dorsally, gradually broader ventrally with a short manubrium.

Etymology.

Latin adjective angustus , meaning narrow. This is the most elongated species in the genus in the Afrotropical region.

Distribution and biology.

Only known from the type locality. It was taken together with M. camerunus (Eggers, 1919) under thick bark of a fallen Ficus tree. Both species used entrance holes made by Xyleborus principalis Eichhoff, 1878.