Elaeidobius subvittatus ( Faust, 1898 )

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 : 9-11

Elaeidobius subvittatus ( Faust, 1898)

Figs 1C , 2C , 4C , 5 A–B, E, G, M, 7

Derelomus subvittatus Faust, 1898: 224 .

Derelomus maynei Hustache, 1924: 75 [syn. by Marshall 1930: 575].

Derelomus elaeisae Bondar, 1942: 461 [syn. by Kuschel 1955: 310].

Elaedobius subvittatus – Kuschel, 1955: 310.

Material examined

Holotype

DEMOCRATIC REPUBLIC OF CONGO • “ Landana. Congo. Oberthur” “ subvittatus Fst. ” “Coll. J. Faust. Aukauf 1900” “type” “Staatl. Museum für. Tierkunde Dresden” “ Holotype ♀. Derelomus subvittatus Faust, 1898 . Kuschel 2013” “ Elaeidobius subvittatus ( Faust, 1898) . Kuschel 2013”; MTD.

Other material

ANGOLA • 10 ♂♂, 13 ♀♀; CE Salazar ; 9.16º S, 14.55º E; 14 May 1973; Carvalho leg.; oil palm inflorescence; TMP .

CAMEROON • 1 ♂; Bertoua , Bindzia; 15 Mar. 2019; J. Haran leg.; JHAR02229_0101 ; CBGP .

DEMOCRATIC REPUBLIC OF CONGO • 1 ♂, lectotype of Derelomus maynei Hustache, 1924 [here designated], labelled as “ Elaeidobius . subvittatus ( Faust 1898) . Kuschel 2009”; Yambata; 10 Dec. 1912; R Mayné leg.; MRAC • 2 ♀♀, paralectotypes of Derelomus . maynei Hustache, 1924 ; same collection data as for preceding; MRAC • 1 ♂; Haut-Uelé, Moto ; 1922; L. Burgeon leg.; MRAC • 1 ♀; Mbwasa; 30 Nov. 1912; MRAC • 4 specs, sex not determined; same collection data as for preceding; IRSNB .

TOGO • 1 ♂; Toné ; 2015; JHAR00275_0101 ; CBGP.

Diagnosis (♂ ♀)

BODY LENGTH. 1.4–2.2 mm.

COLOUR. Variable in colour, partly or entirely yellowish or dark brown, on more western populations usually with a pair of abbreviated dark stripes on prothorax, and a stripe on interstriae 4–5, with a slightly darkened suture; on eastern specimens prevailing darker colour, especially with prothorax usually becoming more extensively or entirely dark, and markings on elytra vaguer or obliterated.

HEAD. Forehead slightly impressed. Rostrum in male as long as prothorax, in female 1.2 to 1.3 × as long as prothorax, with small postmental tubercle in male visible in lateral view.

PROTHORAX. Disc lacking impressions; carina interrupted or not at collar, with small cuticular expansion, in lateral view gently curved upwards towards apex.

ELYTRA. Interstriae with a distinctive row of elongate hairs on middle, hairs as long as width of interstriae; striae with a row of very short recumbent hairs; prosternum in male large and trilobed, or rudimentary and reduced to a cuticular elevation, sometimes absent.

ABDOMEN. Ventrites 1–2 medially flattened, 5 gently rounded at apex. Tergites 1–6 medially divided; tergite 7 in males truncate; plectral pegs 4 on pale line.

GENITALIA. Penis as long as last three ventrites plus ¼ of ventrite 2; body 3 × as long as apodemes, about 4 × as long as wide (ratio w/l: 0.24), slightly asymmetrical, tilted to the right ( Fig. 4C ); internal sac without an obvious sclerite.

Life history

Elaeis guineensis (Arecaceae) the oil palm, on inflorescences ( Mariau & Genty 1988).

Distribution

Angola (Landana); Benin (Cotonou, Dassa, Niaouli, Pobè); Cameroon (Bota, Edu Ngat, Likomba, Moliwe, Tiko); Democratic Republic of Congo (Haut-Lopori, Yambula); Gabon (Kome estate, Bokové); Ghana (Kwae); Ivory Coast (Banoua, Boudoukal); Nigeria (Obaretin); Senegal (Malika – Dakar); Sierra Leone (Njala); Togo (Toné). Introduced populations: Brazil (Bahía); Colombia (Campo Alegre); French Guiana (Kourou).

Remarks

Elaeidobius subvittatus is readily distinguished from all other species by its smaller size, and in males by a small tubercle on the underside at the rostrum apex. The populations of South America were introduced accidentally. This taxon was described on a single female from Landana. In the collection of J. Faust housed at MTD, we found this specimen bearing a red “type” label with the identification “ subvittatus Fst. ”, “Landana, Congo ”. This specimen is the holotype of Derelomus subvittatus Faust, 1898 and was labelled accordingly.

Derelomus maynei Hustache, 1924 , was described from three specimens (1 ♂, 2 ♀♀) from Yambata, 10 Dec. 1912 ( Democratic Republic of Congo). This species was then put in synonymy with D. subvittatus (= Elaeidobius subvittatus Faust ) by Marshall (1930). The three syntypes of D. maynei were located in MRAC. The male is designated here as the lectotype of this species and the two females are labelled as paralectotypes.

Species-group plagiatus

Diagnosis

Characterised by larger size and slender body. Prosternum in male never armed with a protruding process. Pronotum with depressions and fold on anterior half and fovea on middle of disc on either side of midline. Lateral carina of prothorax regular, not forming a constriction or indentation near collar ( Fig. 5C ). Five species in this group.

Figures

Fig. 1. Habitus of males and females of species of Elaeidobius Kuschel, 1952. A. E. bilineatus (Hustache, 1924) comb. nov., Dakar, Senegal. B. E. spatulifer (Marshall, 1950) comb. nov., holotype, Thysville, Democratic Republic of Congo (MRAC). C. E. subvittatus (Faust, 1898), Dakar, Senegal. D. E. kamerunicus (Faust, 1898) comb. nov. (JHAR00209). E. E. pilimargo Haran & Kuschel sp. nov. (JHAR00409). F. E. piliventris Haran & Kuschel sp. nov. (JHAR02182). G. E. plagiatus (Fåhraeus, 1844) comb. nov. (JHAR00272). H. E. singularis (Faust, 1898) comb. nov. (JHAR00283). Scale bars = 1 mm.

Fig. 2. Head and prothorax in lateral view of species of Elaeidobius Kuschel, 1952 (Part 1). A. E. bilineatus (Hustache, 1924) comb. nov., Dakar, Senegal. B. E. spatulifer (Marshall, 1950) comb. nov., holotype, Thysville, Democratic Republic of Congo (MRAC). C. E. subvittatus (Faust, 1898), Dakar, Senegal. D. E. kamerunicus (Faust, 1898) comb. nov. (JHAR00209). Not to scale.

Fig. 4. Penis of males of species of the genus Elaeidobius Kuschel, 1952 in dorsal (left) and lateral (right) view. A. E. bilineatus (Hustache, 1924) comb. nov., Dakar, Senegal. B. E. spatulifer (Marshall, 1950) comb. nov., holotype, Thysville, Democratic Republic of Congo (MRAC). C. E. subvittatus (Faust, 1898), Dakar, Senegal. D. E. kamerunicus (Faust, 1898) comb. nov. (JHAR00209). E. E. pilimargo Haran & Kuschel sp. nov. (JHAR00409). F. E. piliventris Haran & Kuschel sp. nov. (JHAR02182). G. E. plagiatus (Fåhraeus, 1844) comb. nov. (JHAR00272). H. E. singularis (Faust, 1898) comb. nov. (JHAR00283). Scale bars = 100 µm.

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.