Afromicracis concava Jordal, 2021

Jordal, Bjarte, 2021, Small, uniform, and rarely collected-an integrated taxonomic revision of Afromicracis bark beetles (Coleoptera, Scolytinae), Zootaxa 4981 (1), pp. 70-88 : 78

Afromicracis concava Jordal , sp. nov.

urn:lsid:zoobank.org:act:E4485898-AF84-4EB6-B706-E653E39A985C

( Figs 21, 23, 25, 26 , 54 , 57 )

Type material. Holotype male: Cameroon, SW Province, [Mt. Cameroon] Mann Spring , 2000 m [GIS: 4.129, 9.134], ex Vernonia branch, 26.Nov.2007, B. Jordal leg. Allotype and paratypes (6): same data as HT. Holotype, allotype and four paratypes in ZMUB, two paratypes in NHMW.

Diagnosis. Male frons strongly concave, smooth without punctures and setae. Protibiae slightly widened at apicolateral corner, with 3–5 socketed denticles.

Description, male. Length 1.5–1.8 mm, 2.5–2.6 × as long as wide. Colour reddish brown. Frons concave, smooth, impunctate, glabrous, upper median part with transverse carina, laterally with acute nodules just above eyes; antennal scapus with few setae; club with dense setae at margins at basal fourth, and one complete suture marked by setae on apical fourth. Pronotum trapezoid, with asperities on anterior half separated by half their size, subcontiguous near summit; cuticle on posterior half rugose; vestiture consisting of hair-like setae between asperities, spatulate setae on posterior half. Elytral striae not impressed, interstriae smooth, with uniseriate rows of spatulate setae spaced by their length; strial setae minute, shorter than distance between them. Ventrites. Setae on meso- and metaventrites long, unifid, each 2–4 × longer than interstrial setae. Legs. Protibiae narrow, lateral margin slightly expanded near apex, with 3–5 denticles on lateral and apical margin. Genitalia. Apophyses twice as long as penis, dorsoventrally strongly curved; flagellum long and thin, coiled; tegmen missing, a V-shaped hollow structure along apophyses possibly associated with flagellum coil. Spiculum gastrale as long as aedeagus, with small fork.

Etymology. The name is a feminine nominative adjective meaning hollow or concave, referring to the strongly impressed male frons—a highly unusual feature in male micracidines.

Distribution and biology. Only known from the type locality at Mann Spring, Mount Cameroon. Specimens were dissected from a variety of unusual host plants in different plant orders, including a Hypericum tree ( Hypericaceae ), and from lignified herbs of Vernonia (Asteraceae) , Solanecio mannii (Asteraceae) and Plectranthus (Lamiaceae) . They fed on the bark or cortex of the first three hosts. In Plectranthus the beetles were found in the woody roots pulled out from the soil. In Vernonia both adults and larvae excavated longitudinal tunnels between fibres just beneath the cortex.

Dead plants were apparently colonized by females although maturation feeding cannot be ruled out. In other samples, a male with one female were later joined by additional females; usually a total of three or four females were present in one harem. The second female joined approximately after the first female laid 10 eggs. Broods per female ranged between 23–39 (average 31, n=8).

Figures

FIGURE 54. Distribution of selected Afromicracis species.

FIGURES 21–27. Dorsal lateral and front view of Afromicracis concava male holotype (21, 23, 25), female allotype (26), and Afromicracis longa holotype (male?) (22, 24, 27).

FIGURES 55–57. Internal body structures in Afromicracis. Proventriculus (55) and male aedeagus (56) of A. densisetosa and male aedeagus of A. concava (57).