Conicobruchus strangulatus Fahraeus 1839

Conicobruchus strangulatus (Fåhraeus, 1839)

Bruchus strangulatus Fåhraeus, 1839:4

Bruchus hargreavesi Pic, 1933:133, syn. nov. Bruchidius hargreavesi: De Luca, 1965:58 Conicobruchus strangulatus: Decelle, 1951:181 Bruchidius strangulatus Prevett, 1967:176

Material examined. Paratype (female) of Bruchus hargreavesi: Uganda: Kampala, ii.1932, ex pods of Crotalaria [MNHN]

Other material: Burkina-Faso: 1♂, Bobo-Dioulasso, 1.xi.2003, light trap [1♂ 00714] (H. Perrin) [MNHN]. Mali: 2♂, 7♀, Bafing, vi.2008, ex C. cf goreensis [1♂ 0 0 614, specimen GK116 used for DNA extraction] (G.J. Kergoat) [MNHN]. Senegal: 18♂, 13♀, 5km N. Missira, 25.xi.1995, ex C. glaucoides [1♂ 14495, 1♀ 02210] (H. & A. Delobel) [CBGP]; 4♂, 11♀, Nianing, xi.1998, ex C. perrottetii [1♂ 19207, 1♀ 11307] (H. & A. Delobel) [CBGP]; 2♂, 2♀, Dakar, 15.ix.1999, ex C. podocarpa [1♂ 0 2699, specimen Xh1 used for DNA extraction] (H. & A. Delobel) [CBGP]; 1♂, 1♀, 5 km N. Missira, 11.xi.1995, ex C. comosa (H. & A. Delobel) [CBGP]; 1♂, Joal - Samba Dia, 19.xi.1995, ex C. cf goreensis [1♂ 14395] (H. & A. Delobel) [CBGP].

Color variable, with two distinct forms: darker specimens can be entirely black whereas lighter specimens are dark reddish brown, with antennae black. Specimens of the lighter form were formerly considered as a distinct species (hargreavesi).

Other important morphological traits are as follows: pronotum 1.6–1.7 times wider at base than long; lack of white hair spots on pronotum (setation uniformly pale greyish or yellowish); strong ocellate punctation on interstriae, more or less aligned, particularly deep on elytral base in some specimens; hind femur with small acute tooth.

Male genitalia. Median lobe (Fig. 10) of moderate length, stout (maximum width excluding basal hood/ total length = 0.16), strongly widened apically, basal hood moderately widened, concave posteriorly; ventral valve large, subtriangular, with apex acute, bearing numerous sensillae and two lateral groups of 5 to 10 setae; no hinge sclerite; internal sac without central column of tubercles, but with rather dense hyaline scales and tubercles, ending posteriorly in a dorsal mass of small, poorly sclerotized teeth, blending into a short series of well sclerotized teeth of variable length; a pair of strong ventro-lateral dented rods similar to those observed in Conicobruchus nodieri and C. astragalinae, varying in size and shape, from short and straight (Fig 12) to long and crescent (Fig. 13) or rod-shaped (Fig. 14), sometimes very long and articulated (Fig. 15); between these from zero to three isolated teeth; posteriorly a zone with a variable number of strong, isolated sclerotized teeth: absent in specimens from Dakar (Fig. 13) and Bafing (Fig. 15), numerous in male from Missira (Fig. 16); then again two groups of dented sticks or masses, clearly rod-shaped as in Fig. 16 to ill-defined as in male from Nianing (Fig. 17); apical ampoule devoid of any ornamentation, gonopore without sclerotization; basal strut narrow, without keel (Fig. 11); lateral lobes cleft to 85% their length; apex modified, with two lips, the dorsal one bearing about twelve long setae, the ventral one with a dense group of short sensillae.

Biology. Examined material was reared from pods of Crotalaria comosa, C. glaucoides Baker f., C. cf goreensis, C. perrottetii, C. podocarpa. Recorded from other Crotalaria species: C. calycina Schrank, C. leprieurii Guill. & Perr., C. ochroleuca G. D o n, and C. subcapitata De Wild. (Gillon et al., 1992). Crotalaria pods usually contain a large number of small seeds; Conicobruchus strangulatus larvae are external feeders, at least during the last phases of their development, because their body is much larger than the size of individual seeds; when mature, larvae weave a white cocoon inside the inflated pod, attached to its wall, and emergence occurs through a circular hole. Development of young larvae seems impossible in mature, dry seeds.

Distribution. Fåhraeus' types are from Senegal and Republic of South Africa; Pic’s typical series of Bruchus hargreavesi is from Uganda; material seen is from Burkina Faso, Mali, Senegal; also reported from Angola (Decelle, 1975), Congo (Decelle, 1951, 1960, Rasplus, 1989), Eritrea (Zampetti, 1988), Ethiopia (Decelle 1971), Ivory Coast (Rasplus, 1989; Gillon et al., 1992), Nigeria (Prevett, 1971), Senegal (Decelle, 1969) and Togo (Woegan et al., 1997).

Discussion. Conicobruchus strangulatus cannot be confounded with the three species that have a red last visible tergite (C. atrosuturalis, C. decoratus, C. rubricollis). Differences in elytral setation easily separate C. strangulatus from C. cicatricosus (uniform in C. strangulatus, mix of bare spots and densely setose patches in C. cicatricosus). Finally it can be distinguished from C. flabellicornis based on the presence of brushes and spots of dense white setae on the pronotum (absent in C. strangulatus, present in C. flabellicornis).

Conicobruchus strangulatus is the type species of genus Conicobruchus Decelle. Senegalese specimens are either of the lighter (hargreavesi) or of the darker (strangulatus) form. The fact that specimens of both forms emerged from pods of the same host-plant in the same location provides support to establish the synonymy Bruchus hargreavesi Pic = Conicobruchus strangulatus (Fåhraeus).

Phylogenetic analyses. Maximum likelihood analyses yield a best ML tree with a likelihood score of - 25368.23 (Fig. 18). The genus Conicobruchus is recovered monophyletic with a high support (BV of 97%). As in the study of Kergoat et al. (2011), Bruchidius biguttatus and B. cisti appear closely related to the genus Conicobruchus (BV of 93%). Within the genus Conicobruchus the relationships are very similar to those inferred in Kergoat et al. (2011). The six species corresponding to the Conicobruchus strangulatus species group cluster together, with a high bootstrap support (BV of 94%). The newly sequenced species Conicobruchus indicus is found sister to C. kidevuensis, and appear unrelated to the species of the C. strangulatus species group. Another newly sequenced species, C. medaniensis is found sister to C. albopubens with a high support (BV of 100%). Within the C. strangulatus species group a clade composed of C. decoratus and C. rubricollis is sister (BV of 94%) to a wellsupported (BV of 89%) clade of four species. The latter is encompasses C. cicatricosus on the one hand and a subclade that groups C. flabellicornis sister to C. atrosuturalis and C. strangulatus on the other.