Aphanarthrum capense Jordal

Jordal, Bjarte H., 2009, Two new species of Aphanarthrum Wollaston (Coleoptera: Curculionidae, Scolytinae) associated with Euphorbia in South Africa, Zootaxa 1983, pp. 54-62 : 55-57

Aphanarthrum capense Jordal , sp. n.

( Figs. 1 A, B)

Diagnosis. This species is distinguished from all other Aphanarthrum by the uniformly dark brown colour of the pronotum and elytra and by the male genitalia having a cluster of caudadly pointed spines and the lamina anteriorly recurved into hooks. It is furthermore distinguished from all North African and Macaronesian species by the finely asperate pronotum and from A. maculatum by the much larger size of the aedeagus and by having 4 socketed teeth on the protibia and 4-5 teeth on the meso- and metatibia. COI sequences: EU143701 - EU143702 . EF-1α sequences: EU143705 – EU143706 .

Description. Length 1.3–1.8 mm, 2.5–2.7 times longer than wide; colour dark brown, legs and antennae yellow to light brown. Frons slightly convex, surface reticulate and sparsely punctured above upper level of eyes, flat, shiny and densely granulate below; scattered short setae present close to epistoma. Eyes deeply emarginated at level of antennal insertion, separated above by 2.0–2.2 times their length (anterior to posterior margin). Antennal club 1.4–1.5 times longer than wide, laterally constricted at sutures 1 and 2, sutures incomplete at middle, suture 1 recurved and septate, a few setae present; funiculus 1-segmented; scapus as long as club and funiculus combined, with a few scattered setae. Pronotum 1.0–1.1 times longer than wide; sides curved, slightly diverging in basal half, slightly constricted at anterior third, narrowly rounded in front; surface reticulate, punctures shallow, spaced by 1-2 times their diameter, punctures replaced by granules and asperities on anterior half; vestiture consisting of scarce hair-like setae. Elytra 1.5–1.7 times longer than wide, 1.6–1.8 times longer than pronotum, sides straight and parallel in basal two-thirds, apically broadly rounded. Scutellum small and round, flush with elytra. Base of elytra straight; stria 1 moderately impressed, others not, punctures small and shallow, spaced by their diameter; interstriae as wide as striae, punctures slightly smaller than those in striae. Declivity gradually rounded, stria 1 sometimes indistinctly impressed (males?). Vestiture varying between paratypes, in holotype consisting of uniseriate rows of hair-like interstrial and strial setae, interstrial setae twice as long as strial setae, spaced by less than length of a seta; all setae shorter and denser on declivity. Procoxae projecting well below prosternum, subcontiguous; prosternal process narrow, long and acute; mesocoxae separated by the width of scapus, mesoventral process descending; metacoxae separated by length of a coxa. Protibia on outer lateral edge with four socketed teeth, meso- and metatibiae usually with five socketed teeth; all tibiae with inner terminal mucro. Aedeagus about 2.3 times longer than wide, distinction between body and apodemes faint, body subparallel in basal half, then narrowly rounded towards apex. Terminal plates parallel, less than one-third as long as aedeagus. Lumen containing a cluster of caudadly pointing and weakly sclerotised spines situated above a strongly sclerotised U-shaped lamina; anterior ends of lamina recurved into a hook. Tegmen open dorsally, weakly sclerotised, broad and strongly asymmetrical. Spiculum gastrale about as long as aedeagus, abruptly curved at caudal end, strongly sclerotised, with a small, elongated knob in middle.

Material examined. Holotype (sex not determined): " South Africa, Eastern Cape Province, Ecca Pass, N. Grahamstown. Ex Euphorbia triangularis , 16 Nov. 2006, B. Jordal leg." [ SAM]. Paratypes (n=19): same data as for holotype (13 in SAM, 4 in BHJ collection).

Etymology. The species is named after the Cape region of South Africa, where it was collected.

Biology. Aphanarthrum capense completes its entire life cycle in dead branches of Euphorbia triangularis and possibly other succulent Euphorbia . Species of this genus and Coleobothrus are highly selective in their host preferences and there are no observations reported so far of host switching between succulent and arborescent Euphorbia ( Jordal & Hewitt 2004; Jordal 2006). Mating in A. capense occurs just inside the entrance hole made by the individual arriving first (usually a female). The male usually stays with the female and together they excavate irregular tunnels for feeding and oviposition. About 3– 6 eggs are laid by one female. Larvae and teneral adults feed on dead plant tissue until mature adults leave in search for new breeding sites.

Figures

FIGURE 1. Habitus and male genitalia of Aphanarthrum species. A – B: A. capense sp. n.; C – D: A. maculatum sp. n.