Drosophila (Sophophora) vulcana Graber, 1957

Yassin, Amir, Suwalski, Arnaud & Raveloson Ravaomanarivo, Lala H., 2019, Resolving the synonymy and polyphyly of the ‘ Drosophila bakoue species complex’ (Diptera: Drosophilidae: ‘ D. montium species group’) with descriptions of two new species from Madagascar, European Journal of Taxonomy 532, pp. 1-26 : 20

Drosophila (Sophophora) vulcana Graber, 1957

Figs 1–2 , 8 A–B, 9A, C, E

Drosophila (Sophophora) vulcana Graber, 1957: 309 .

Diagnosis

Male abdominal tergites T5 with a contiguous diffuse dark brown stripe, T6 light with a very faint dark stripe ( Fig. 8A ); hypandrium narrow with an elongated anterior phragma; outer paraphyses posterior margin curved; aedeagus pilosity tapering at tip ( Fig. 9A, C ); female abdominal tergites T2–T4 without a diffuse pale region on the antero-distal margins, T5 with diffusely dark stripe ( Fig. 8B ); oviscapt fourth posterior peg-like outer ovisensillum on the same axis with the third and fifth ovisensilla, with anterior ovisensilla short and thick ( Fig. 9E ).

Type material

Holotype

DEMOCRATIC REPUBLIC OF THE CONGO • ♂; Kivu Province, Mount Bugulumiza ; 1954; ZMUZ.

Description

As in Graber (1957) for the type material and Bock & Wheeler (1972) for a strain from Mount Selinda ( Zimbabwe).

Distribution

Democratic Republic of the Congo (type), Kenya, Tanzania and Zimbabwe.

Remarks

The type material of Graber (1957) consisted of six males and six females from Kivu Province ( Democratic Republic of the Congo). Tsacas & Chassagnard (1992) examined this material and found five males and six females (probably the male used by Graber for dissection and genitalia illustration was lost). Of the five remaining males, only one belonged to a ‘ D. montium species group’ that Tsacas (1984) considered D. ifestia . Of the six females, five belonged to the ‘ D. montium species group’. Two females sojourned in alcohol and lost coloration, whereas the remaining three females were pinned and had dark wings, pleurae and legs in agreement with the original description of Graber (1957). For abdominal coloration, this description indicates “uniform schwarzbraune glänzende Tergite” (uniform black-brown shining tergite). Bock & Wheeler (1972) described a strain from Mount Selinda ( Zimbabwe) attributed to D. vulcana by S. Paterson. They showed, however, the presence of two types of male genitalia in this strain. Tsacas & Chassagnard (1992) reanalyzed this strain and found that only one of the two types existed at the time of their examination. They concluded that the original strain consisted of two distinct species with one having subsequently gone extinct. They also suggested that male genitalia of the type of Séguy (1938) for D. seguyi corresponded to the genitalia of the surviving species in this strain. We dissected males from the strain of Mount Selinda and found that the illustration of Tsacas & Chassagnard (1992) of the holotype of D. seguyi lacks the partial fusion of the cercal ventral lobe (secondary clasper), characteristic of the strain of Mount Selinda. Moreover, the pale male abdominal pigmentation of the strain of Bock & Wheeler (1972) ( Fig. 4G ) clearly contrasts with the description of Séguy (1938) of D. seguyi : “tergites largement bordés de brun noir, dernier segment d’un noir luisant” [tergites with large brownish black stripe, last segment shiny black]. On the contrary, abdominal pigmentation of the strain of Mount Selinda corresponded to the abovementioned original description of Graber (1957). Therefore, we concur with Bock & Wheeler (1972) for considering the strain of Mount Selinda to belong to D. vulcana . Okada et al. (1988) recorded this species from Tanzania, and Takada et al. (1990) indicated its presence in Kenya, suggesting its widespread distribution in East Africa. Females do not exhibit a sex-limited color dimorphism.

Figures

Fig. 1. Bayesian phylogeny of 19 species from the ‘D. montium species group’ Da Lage, 2007 inferred from complete mitochondrial genomes. Nodes supported by 100% posterior probability (pp) are not labeled, those with pp> 90% or 60% are labeled with gray and white circles, respectively. Species belonging to the ‘D. bocqueti species complex’ and the ‘D. bakoue species complex’ are highlighted in orange and green, respectively. ‘K’ and ‘B’ refer to the strains of D. aff tsacasi Bock & Wheeler, 1972 from Kenya and Bioko Island, respectively.

Fig. 2. Comparison of Bayesian phylogenies of the ‘D. seguyi species subgroup’ Yassin, 2018 inferred from mitochondrial COI (left) and nuclear Amyrel (right) genes. Nodes supported by>95% posterior probability (pp) are labeled with black circles. An asterisk refers to species sequenced here, whereas two asterisks refer to the sequence of D. vulcana Graber, 1957 of Da Lage et al. (2007), which turned out to belong to D. seguyi Smart, 1945 from Kenya (see the text). Note the discrepancy in position of different geographical strains of D. bakoue Tsacas & Lachaise, 1974 (in red) between the two genes. Species belonging to ‘D. bocqueti species complex’ Tsacas & Lachaise, 1974, ‘D. bakoue species complex’ Rafael, 1984, ‘D. nikananu species complex’ Tsacas & Chassagnard, 1992, and ‘D. megapyga species complex’ Lachaise & Tsacas, 2001 are highlighted in orange, green, yellow and red, respectively.

Fig. 8. Adult habitus. A–B. D. vulcana Graber, 1957 (MNHN). A. ♂. B. ♀. C–D. D. mylenae David & Yassin sp. nov. (MNHN). C. ♂. D. ♀. Scale bar = 1 mm.

Fig. 9. Terminalia of the ‘D. vulcana species complex’. A, C, E. D. vulcana Graber, 1957 (MNHN). A, C. ♂. E. ♀. B, D, F. D. mylenae David & Yassin sp. nov. (MNHN). B, D. ♂. F. ♀. Scale bars: A–B = 50 µm; D–F = 100 µm.

Fig. 4. Adult habitus. A–B. D. seguyi Smart, 1945 (MNHN). A. ♂. B. ♀. C–D. D. malagassya Tsacas & Rafael, 1982 (MNHN). C. ♂. D. ♀. E–F. D. curta Chassagnard & Tsacas, 1997 (MNHN). E. ♂. F. ♀. G–H. D. chocolata Yassin & David sp. nov. (MNHN). G. ♂. H. ♀. Only dark morphs of females of species with female-limited color dimorphism are shown. Scale bar = 1 mm.