Drosophila (Sophophora) bakoue Tsacas & Lachaise, 1974

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 : 8

Drosophila (Sophophora) bakoue Tsacas & Lachaise, 1974

Fig. 2

Drosophila (Sophophora) bakoue Tsacas & Lachaise, 1974: 197 .

Diagnosis

Male with sex combs on the two first tarsomeres of the foreleg and completely yellow abdominal tergites; surstylus without dorsal tooth-like protuberance.

Type material

Holotype

IVORY COAST • ♂; Lamto ; 6°13′ N, 5°02′ W; 22 Dec. 1970; D. Lachaise leg.; MNHN.

Distribution

Ivory Coast (type), Benin, Cameroon, Congo, Gabon, Malawi, Nigeria, and São Tomé Island (new location).

Remarks

D. bakoue resembles the species of the ‘ D. nikananu species complex’ Tsacas & Chassagnard, 1992 in males having completely yellow abdominal tergites. However, it differs from the species of the ‘ D. nikananu species complex’ in males having sex combs on the two first tarsomeres of the foreleg (the comb is lost or reduced on the second tarsomere in the ‘ D. nikananu species complex’) and lacking a dorsal tooth-like protuberance on the surstylus.

Lachaise (1979) attributed a laboratory strain collected from Makoukou ( Gabon) to this species, and showed that it could produce fertile F 1 females and sterile F 1 males when its females were crossed with males of the strain of D. vulcana of Bock & Wheeler (1972). Rafael (1984) attributed another strain from Kunden ( Cameroon) to D. bakoue and showed that it could not hybridize with the same strain of D. vulcana or with the strain of D. tsacasi of Bock & Wheeler (1972). Intriguingly, Rafael (1984) pointed out that both the Gabonese and Cameroonian strains of D. bakoue showed some differences in body size and pigmentation from the type material from Ivory Coast. She also found that the Cameroonian strain hybridized readily with D. malagassya , though both F1 sexes were sterile. Kopp (2016) analyzed a strain collected from the island of São Tomé and attributed to D. bakoue by J.R. David, and found that it produced sterile F 1 males and females when crossed with the same strain of D. tsacasi . Da Lage et al. (2007) analyzed the sequence of the nuclear gene Amyrel from a strain collected from Benin and found it to be sister to the strain of D. tsacasi of Bock & Wheeler (1972). Prigent et al. (2017) partially sequenced the mitochondrial gene COI from two specimens from Mount Oku in Cameroon and did not recover such affinity ( Fig. 2 ). These results suggest that at least two different species may have been attributed to D. bakoue , from which the strains from Benin and São Tomé are closely related to D. tsacasi , whereas the strains from Gabon and Cameroon are distant. The relation of these species with the true D. bakoue from Ivory Coast needs more investigations.

Figures

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.