Elaeidobius Kuschel, 1952

Haran, Julien M., Beaudoin-Ollivier, Laurence, Benoit, Laure & Kuschel, Guillermo, 2020, Revision of the palm-pollinating weevil genus Elaeidobius Kuschel, 1952 (Curculionidae, Curculioninae, Derelomini) with descriptions of two new species, European Journal of Taxonomy 684, pp. 1-32 : 4-5

Genus Elaeidobius Kuschel, 1952

Elaeidobius Kuschel, 1952: 272 ; 1955: 310.

Type species

Derelomus elaeisae Bondar, 1942 [= Derelomus subvitttatus Faust, 1898 ].

Diagnosis

Eyes flat, following contour of head. Head not or hardly depressed above forehead. Elytra with interstria 9 or 10 costate in part, with costa at apex flat, not extending to apical margin; area on declivity between interstriae 3 and 9 not impressed. Fore and middle tibiae mucronate, hind tibiae with or without mucro. Claws free, simple. Tergites well-pigmented, divided or not along midline; spiracle surrounding not darkened.

Among the Afrotropical Derelomini , the genus Elaeidobius is close to the genera Derelomus and Prosoestus Faust, 1899 , which both contain species associated with inflorescences of Arecaceae Bercht. & J.Presl. The species belonging to the genus Elaeidobius can be distinguished by the key provided at the end of the results section.

Distribution

This genus is native to West and central Africa ( Table 2 ). It has been introduced into Madagascar, Asia ( Burma, India, Indonesia, Malaysia, Thailand and Solomon Islands) and to the Americas ( Brazil, Colombia, Ecuador, Guatemala, North America and Peru) ( O’Brien & Woodruff 1986; Mariau & Genty 1988).

Life history

Larvae of the genus Elaeidobius develop in male flowers of the African oil palm, Elaeis guineensis ( Arecales , Arecaceae ), adults settle on the inflorescences and feed on pollen ( Fig. 7 , see Li et al. 2019 for a review). Adults fly during the day, attracted by the odour emitted by the inflorescences (Beaudoin-Ollivier et al. 2017). They transfer the pollen to female flowers, lured by their odours, which are similar to the male ones ( Opute 1975; Lajis et al. 1985; Hussein et al. 1989).

Species-group: subvittatus

Diagnosis

Characterised by a smaller size (1.4–3.0 mm) and a more compact body. Prosternum in male armed with a protruding process, variable in shape and size, occasionally absent in smaller specimens. Pronotum lacking depressions and fold on anterior half and fovea on middle of disc on either side of midline. Lateral carina of prothorax forming a constriction near collar ( Fig. 5A ), followed by a distinct indentation. Three species in this group.

Figures

Fig. 7. Adults of Elaeidobius plagiatus (Fåhraeus, 1844) comb. nov. (left) and E. subvittatus (Faust, 1898) (right) feeding on male inflorescence of Elaeis guineensis Jacq.

Fig. 5. Details of morphology of Elaeidobius spp. A. Pronotum of E. subvittatus (Faust, 1898) in dorsal view showing the flat pronotum and the lateral cuticular expansion near head. B. Pronotum of E. subvittatus (Faust, 1898) in ventral view, showing the trilobate cuticular expansion between the coxae. C. Pronotum of E. plagiatus (Fåhraeus, 1844) comb. nov. in dorsal view showing the fovea on either side of midline. D. Apex of rostrum of E. bilineatus (Hustache, 1924) comb. nov. in lateral view. E. Apex of rostrum of E. subvittatus (Faust, 1898) in lateral view showing the protruding tubercle on underside. F. Elytra of E. bilineatus (Hustache, 1924) comb. nov. in dorsal view. G. Elytra of E. subvittatus (Faust, 1898) in dorsal view. H. Elytra of E. singularis (Faust, 1898) comb. nov. in lateral view. I. Elytra of E. kamerunicus (Faust, 1898) comb. nov. in lateral view. J–K. Abdominal sternites of male of E. piliventris Haran & Kuschel sp. nov. showing the median impression of the first two segments, flanked by a fringe of semi-erect hairs. L. Scutellum of E. plagiatus (Fåhraeus, 1844) comb. nov. in lateral view showing erect setae on tumescent base of interstria 4. M. Pronotum of dark specimens of E. subvittatus (Faust, 1898) in dorsal view. Not to scale.