Conicobruchus decoratus ( Fåhraeus, 1871 ), Fahraeus, 1871

Le Ru, Bruno P., Delobel, Alex, György, Zoltán, Genson, Gwenaëlle & Kergoat, Gael J., 2014, Taxonomy, host-plant associations and phylogeny of African Crotalaria - feeding seed beetles (Coleoptera, Chrysomelidae, Bruchinae): the Conicobruchus strangulatus (Fåhraeus) species group, Zootaxa 3895 (2), pp. 238-256 : 246-247

Conicobruchus decoratus ( Fåhraeus, 1871)

Bruchus decoratus Fåhraeus, 1871:448

Bruchus decoratus atrodorsalis Decelle, 1960:137 , syn. nov. Bruchus nigromaculatus Pic, 1929 (synonymy in Decelle 1961: 8) Bruchidius decoratus Decelle, 1975:21

Conicobruchus decoratus: Kergoat et al., 2011:756

Material examined. Type (male) of Bruchus nigromaculatus : Republic of South Africa: Port St John, v.1923, R.E. Turner [dissected, genitalia on card in DMHF].

Other material: Botswana: 1♀, Leribé, 1923 (R. Ellenberger) [ MNHN]. Republic of Mozambique: 1♂, Nova Chupanga, v.1928 (P. Lesne) [ MNHN]. Tanzania: 2♂ (C. Conrads) [ MNHN]. Zambia: 1♂, 2♀, Samununga, 13°37.156’S 24°07.349’E, 1091m, 19.iii.2012, ex Crotalaria aculeata claessensii , [1♂ 0 2012, specimen GK446 used for DNA extraction] (B. Le Ru) [ CBGP].

Body black, with large red parts; head (including antennae), thoracic sternites and legs always black, pronotum and abdomen always red. Elytra entirely black in some specimens, but usually red with more or less extensive black markings ( Fig. 1 ): usually base, humerus, a round spot at basal fourth in interstriae 2 to 4, apical fourth to third of elytra, often also along suture.

Other important morphological traits are as follows: pronotum 1.5 times wider at base than long, its sides almost straight, slightly sinuated, not constricted anteriorly into a neck; moderately lobed posteriorly and laterally, with dense white setation on lobes; strial punctures small, circular, closely spaced, interstriae finely imbricate, shining, with minute punctures; male antennae serrate.

Male genitalia. Median lobe ( Fig. 5 ) of moderate length, stout (maximum width excluding basal hood / total length = 0.15), not widened apically, basal hood moderately widened, not concave posteriorly; ventral valve large, subtriangular, bearing apically numerous sensillae and basally two lateral groups 9–12 setae; no hinge sclerite; internal sac anteriorly with minute spinules and scales, then densely lined with strands of hyaline and sclerotized spines; apical ampoule devoid of any ornamentation, gonopore not sclerotized; basal strut ( Fig. 6 ) narrow, without keel; lateral lobes cleft to about 90% their length; apex modified, with two lips, the dorsal one bearing about 15 setae, the ventral one densely lined with long setation.

Biology. Zambian material was reared from pods of Crotalaria aculeata subsp. claessensii. This constitutes the first report on its biology.

Distribution. Botswana, Democratic Republic of Congo ( Decelle, 1960), Republic of Mozambique, Republic of South Africa, Tanzania and Zambia.

Discussion. Conicobruchus decoratus can be distinguished from other members of the C. strangulatus species group by the shape of the pronotum and structure of male genitalia. Contrary to the other species of the group, in C. decoratus the pronotum is short, its side non-concave and it is not compressed anteriorly into a neck ( Fig. 1 ). Male genitalia are also very distinctive, being less widened anteriorly and the basal strut not concave posteriorly ( Fig. 5 ).

Specimens with black elytra were considered as a subspecies (atrodorsalis) by Decelle (1960). However the pattern of elytral coloration is extremely variable, ranging from red with few black markings to entirely black. Because of this high level of variability we chose to establish the synonymy Bruchus decoratus atrodorsalis Decelle = Conicobruchus decoratus (Fåhraeus) .

Figures

FIGURE 1. Dorsal view of specimens belonging the to six species of the Conicobruchus strangulatus species group.

FIGURES 5 – 7. Conicobruchus decoratus: 5 — median lobe; 6 — basal strut and lateral lobes (specimen 0 2012, Zambia); Conicobruchus flabellicornis: 7 — median lobe (specimen 0 1209, Kenya).