Elaeidobius bilineatus ( Hustache, 1924 ) Haran & Beaudoin-Ollivier & Benoit & Kuschel, 2020

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 : 5-7

Elaeidobius bilineatus ( Hustache, 1924) comb. nov.

Figs 1A , 2A , 4A , 5D–F

Derelomus bilineatus Hustache, 1924: 75 .

Prosoestus armatus Voss, 1956: 629 . syn. nov.

Material examined

Lectotype (here designated)

DEMOCRATIC REPUBLIC OF CONGO • “ HOLOTYPUS [red label]” “Musée du Congo. Haut-Uelé: Moto. -1922. L. Burgeon ” “ Lectotype ♀ [here designated]. Derelomus . bilineatus . Hustache 1924. Kuschel 2009 [red label]” “ Derelomus . bilineatus . Type Hust” “ Elaeidobius . bilineatus . (Hust. 1924) Kuschel 2009”; MRAC.

Paralectotype (here designated)

DEMOCRATIC REPUBLIC OF CONGO • 1 ♀; “Musée du Congo. Haut-Uelé: Moto . -1922. L. Burgeon ” [labelled as follows] “ Paralectotype Derelomus . bilineatus . Hustache 1924. Kuschel 2009”; MRAC .

Other material

DEMOCRATIC REPUBLIC OF CONGO – Haut-Uelé Province • 2 ♀♀; Moto ; 1922; L. Burgeon leg.; MRAC • 1 ♀; same collection data as for preceding; 1920; MRAC • 1 ♀; same collection data as for preceding; Jan. 1927; MRAC • 1 ♀; Watsa; 1922; L. Burgeon leg.; MRAC .

ANGOLA • 6 ♂♂, 15 ♀♀; C.E.Salazar ; 9.16º S, 14.55º E; 14 May 1973; P. Carvalho leg.; oil palm inflorescence; TMP .

IVORY COAST • 1 ♂; Boudoukal; 2014; JHAR00286_0104 ; CBGP .

SENEGAL • 1 ♂, holotype of Prosoestus armatus Voss , 195]; La Digue near Rufisque ; 8 Apr. 1951; Bechyné leg.; NHMB .

Other specimens identified and labelled by G. Kuschel at IFPE, MNHN, MRAC, NHMUK, NZAC, USNM and ZMB .

Diagnosis (♂ ♀)

BODY LENGTH. 2.2–3.0 mm.

COLOUR. Reddish or yellowish brown with dark markings on pronotum and elytra, also sterna darkened.

HEAD. Forehead in both sexes not impressed. Rostrum relatively long, in male 1.5 × as long as prothorax, lacking a postmental tubercle, in female 1.8–1.9 × as long, slender, slightly downcurved.

PROTHORAX. Disc with a pair of dark stripes, slightly convergent; lateral carina continued to apex with a distinct indentation or interrupted, in lateral view strongly curving upwards before apical collar.

ELYTRA. Presence of irregular dark stripes, generally with a short one in middle of interstria 2, and an elongate one along interstria 6 from basal quarter to top of declivity, often expanding on interstriae 5 and 7, a further stripe on interstria 9; punctures of striae as wide as width of interstriae or slightly smaller; interstriae with a row of very short recumbent hairs. Prosternal process in male variously developed, from a large spatulate structure to a reduced or even absent one.

ABDOMEN. Tergites 1 to 6 medially membranous, tergite 4 on sides subtruncate, anteriorly angulate, tergite 7 truncate at apex; row of approximately 15 plectral pegs flanked by narrow, clear sides, area between plectral rows parallel-sided, dark, smooth.

GENITALIA. Penis as long as last two ventrites and half of ventrite 3, body 2.17 × as long as apodemes, about 2 × as long as wide (ratio w/l: 0.56), symmetrical, gradually widening apicad, abruptly apiculate ( Fig. 4A ); internal sac with straight, stiff, robust sclerite half length of body.

Life history

Adults are found on inflorescences of Elaeis guineensis (Arecaceae) , the African oil palm. (JH pers. obs.).

Distribution

Angola (C.E. Salazar (?)); Benin (Cotonou, Dassa, Niaouli); Cameroon (Likomba, Moliwe); Congo (Brazzaville); Democratic Republic of Congo (Haut-Uelé: Moto, Moku Moto, Watsa, Yambula); Ghana (Kumasi, Aburi); Guinea (Nimba); Ivory Coast (Boudoukal); Nigeria (Ibadan, Ife, Lagos); Senegal (Dakar, La Digue); Sierra Leone (Njala); Tanzania (Morogoro); Togo (Kloto).

Remarks

Elaeidobius bilineatus has, in lateral view, the marginal carina of the prothorax strongly upcurved, a character that safely distinguishes this species from all others of the genus. As Elaeidobius is said to be a West African genus, its presence in Tanzania is unexpected and it has to be confirmed whether it is a native or an introduced element. Elaeidobius bilineatus was described by Hustache as Derelomus bilineatus based on two female specimens from Haut Uelé ( Democratic Republic of Congo) ( Hustache 1924). These two specimens were located in the MRAC collection, bearing a red “ holotype ” label. As the original description of this species did not designate a holotype, one of them was designated as the lectotype for this species and was labelled accordingly. The second syntype was labelled as paralectotype. The other specimens from the same collecting event (2 ♀♀) are not part of the type series. We examined the holotype of the species Prosoestus armatus Voss, 1956 , described from a single male specimen from Senegal (La Digue nr Rufisque). A detailed observation of the external and internal morphology of this specimen showed no difference from the lectotype of Elaeidobius bilineatus . As a result of this, Prosoestus armatus Voss, 1956 should be considered as a junior synonym of E. bilineatus .

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.