Elaeidobius singularis ( Faust, 1898 ) 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 : 23-24

Elaeidobius singularis ( Faust, 1898) comb. nov.

Figs. 1H , 3D , 4H , 5H

Derelomus singularis Faust, 1898: 224 .

Derelomus uelensis Hustache, 1932: 68 . syn. nov.

Material examined

Lectotype (here designated)

DEMOCRATIC REPUBLIC OF CONGO • ♂; “ Landana. Congo. Oberthur” “ D singularis Fst. ” “Coll. J. Faust. Ankauf 1900” “ type ” “Staatl. Museum für. Tierkunde Dresden” “ Lectotype ♂ [here designated]. Derelomus singularis Faust, 1898 . Kuschel 2013” “ Elaeidobius singularis ( Faust, 1898) . Kuschel 2013”; MTD.

Paralectotype (here designated)

DEMOCRATIC REPUBLIC OF CONGO • 1 ♀; same collection data as for lectotype; “ Paralectotype ♀. Derelomus singularis Faust, 1898 . Kuschel 2013” “ Elaeidobius singularis ( Faust, 1898) . Kuschel 2013”; MTD .

Other material

DEMOCRATIC REPUBLIC OF CONGO • ♂, lectotype of Derelomus uelensis Hustache, 1932 [here designated], labelled as “ Elaeidobius singularis ( Faust 1898) Kuschel 2009 ”; Haut-Uelé, Moto ; 1922; L. Burgeon; MRAC • 3 ♂♂, 2 ♀♀; Kindu; Nov. 1913; L. Burgeon leg.; MRAC • 1 ♀; Haut-Loporiv ; 1927; J. Ghesquiere leg.; MRAC • 1 ♀; Haut-Uelé, Watsa ; 1922; L. Burgeon leg.; MRAC .

ANGOLA • 2 ♂♂; CE Salazar; 9.16º S, 14.55º E; 14 May 1973; Carvalho leg.; oil palm inflorescence; TMP .

GHANA • 1 ♂; Godbe; 2015; on inflorescences of E. guineensis ; JHAR00283_0101 ; CBGP .

Diagnosis (♂ ♀)

BODY LENGTH. 2.2–3.0 mm.

COLOUR. Yellowish or reddish brown, shiny rostrum in part, meso and metasternum dark; prothorax with vague, dark stripe on sides of discal foveae, elytra usually dark near basal ¼ of interstria 6 and an oblique band from middle of interstria 3 or 4 to ¾ of interstria 8.

HEAD. Forehead in male impressed. Rostrum in male a fraction shorter than prothorax, without erect hairs or tubercle on underside, in female 1.5 × longer than prothorax.

PROTHORAX. Disc with a pair of large, deep foveae; apical collar at base usually with a transverse row of black dots; lateral carina fine, continued to apex.

ELYTRA. Without long erect setae on margin and suture, in male often with a conspicuous swelling at base of interstria, in small males reduced or absent; prosternum without protruding process.

ABDOMEN. Ventrite 1–2 flattened on middle, not impressed, with fine, appressed pubescence and no semi-erect hairs. Tergites 3–6 undivided on midline, tergite 7 strongly advancing forward against tergite 6; granules of stridulatory organ evenly distributed on entire line, up to 18 in number per row.

GENITALIA. Penis a little longer than the last three ventrites; body 2.3 × as long as apodemes, about 2 × as long as wide (ratio w/l: 0.48), symmetrical, tapering with slight curve to apex ( Fig. 4H ); internal sac with a pair of small frena.

Life history

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

Distribution

Benin (Cotonou, Dassa, Niaouli, Pob è); Cameroon (Edu Ngat, Ekondo Titi, Kienke, Mbalmayo, Moliwe); Democratic Republic of Congo (Haut-Lopori, Haut Uelé: Moto, Watsa, Kindu, Landana, Luluabourg); Gabon (Kome Estate); Ghana (Gobbe); Ivory Coast (Bonoua, Boudoukal); Nigeria (Obaretin); Togo (Kloto).

Remarks

Elaeidobius singularis is readily distinguished in the male by having a tumescent 4 th interstria at the base (though reduced or even absent at times in some small individuals), and no semi-erect hairs on the abdomen, and by the elytra without long erect setae on the margin and on the suture. This taxon was described on a male and a female from Landana in the current Democratic Republic of Congo. In the collection of J. Faust housed at MTD, we found a male and a female pinned on the same pin with the identification “ D singularis Faust. ” “Landana, Congo ” and bearing a red “type” label. The description of this species does not refer to a holotype, therefore the male syntype was designated as the lectotype of Derelomus singularis Faust, 1898 and was labelled accordingly. The female syntype was labelled as the paralectotype of this species.

Hustache described D. uelensis based on five specimens collected by L. Burgeon in Moto ( Democratic Republic of Congo). In the collections of the MRAC, only one specimen from Moto could be located and bore a red paratypus label. This specimen is here designated as the lectotype for D. uelensis and labelled accordingly. The other four specimens of this series are from Kindu and not from Moto as reported by Hustache (1932). These specimens also bear paratypus labels and were labelled as paralectotypes of this species. Observations made on the external and internal morphology of specimens of this series showed no difference from the holotype of Elaeidobius singularis . Consequently, the name Derelomus uelensis should be considered as a junior synonym of Elaeidobius singularis .

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. 3. Head and prothorax in lateral view of species of Elaeidobius Kuschel, 1952 (Part 2). A. E. pilimargo Haran & Kuschel sp. nov. (JHAR00409). B. E. piliventris Haran & Kuschel sp. nov. (JHAR02182). C. E. plagiatus (Fåhraeus, 1844) comb. nov. (JHAR00272). D. E. singularis (Faust, 1898) comb. nov. (JHAR00283). 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.