Drosophila (Sophophora) seguyi Smart, 1945

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 : 9-13

Drosophila (Sophophora) seguyi Smart, 1945

Figs 1–2 , 3A , 4 A–B, 5A, 6A–B

Drosophila (Sophophora) seguyi Smart, 1945: 56 .

Diagnosis

Male and female body pigmentation including halters and legs yellow ( Fig. 4 A–B); male abdominal tergites T2–T4 with a thin black stripe expanding on the middle and fainting towards the margin, T5 with a broader stripe, T6 completely black ( Fig. 4A ); dorsalmost surstylus prensiseta on the same axis with remaining prensisetae, hypandrial median process weakly pointed, aedeagus finger-like ( Fig. 5A ); female T2–T5 with a broad black stripe and an expanding grayish area on the margin ( Fig. 4B ); oviscapt fourth posterior peg-like outer ovisensillum on the same axis with the third and fifth ovisensilla ( Fig. 6A ), with anterior ovisensilla short and thick ( Fig. 6B ).

Type material

Holotype

KENYA • ♂; Mount Elgon ; 01°07′ N, 34°31′ E; 2490 m a.s.l.; 1932–1933; R. Jeannel leg.; MNHN.

Distribution

Kenya (type), Cameroon (new record), Malawi, island of Mayotte (new record), Tanzania and Zimbabwe.

Remarks

Two strains (K2 and K59) collected from Mombasa ( Kenya) in 1979 and identified as D. seguyi by T. Okada were studied in genetic studies ( Ohnishi & Watanabe 1984; Zhang et al. 2003; Li et al. 2012; Chen et al. 2013; M. Watada, pers. comm.). These strains were also sent to the laboratory of Gif-sur-Yvette in France, where Léonidas Tsacas and Marie-Thérèse Chassagnard worked. Tsacas & Chassagnard (1992) considered the strain of D. vulcana of Bock & Wheeler (1972) to be the true D. seguyi . In Tsacas’ notebook recording the strains maintained at Gif-sur-Yvette, we found a note by him considering the K59 strain to be the true D. vulcana . This strain was used in the revision of the genus Drosophila Fallén, 1823 of Da Lage et al. (2007), based on the nuclear gene Amyrel, although in the publication, Mount Selinda, the locality of the strain of D. vulcana of Bock & Wheeler (1972), was mistakenly mentioned as the source of the Amyrel sequence (J.-L. Da Lage, pers. comm.). In spite of the suggestion of Tsacas & Chassagnard (1992), we prefer for taxonomic stability to consider both Kenyan strains to belong to the true D. seguyi and to preserve the concept of D. seguyi of Bock & Wheeler (1972). A strain collected in Cameroon by J. Pool in 2004, and preserved in the Drosophila Species Stock Center, was identified based on the mitochondrial gene cytochrome oxidase subunit 2 (COII) as D. seguyi , indicating the broad distribution of this species in Africa.

David et al. (2014) mentioned the presence of a strain of D. malagassya on the island of Mayotte (discussed under D. malagassya above). We have used this strain, as D. cf. malagassya , in our combined phylogenetic study of the montium clade and showed its close affinity to the Kenyan strains of D. seguyi ( Yassin et al. 2016) . Detailed morphological comparisons support the conspecificity of the strains from Kenya and Mayotte. Females of the strain of Mayotte exhibit the characteristic Mendelian color dimorphism, with the black morph being dominant ( Yassin et al. 2016).

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. 3. Photomicrographs of male periphallic organs. A. D. seguyi Smart, 1945 (MNHN). B. D. aff. tsacasi Bock & Wheeler, 1972 (MNHN). C. D. mylenae David & Yassin sp. nov. (MNHN). Scale bars = 0.1 mm.

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.

Fig. 5. Male terminalia of the ‘D. seguyi species complex’. A. D. seguyi Smart, 1945 (MNHN). B. D. malagassya Tsacas & Rafael, 1982 (MNHN). C. D. curta Chassagnard & Tsacas, 1997 (MNHN). D–F. D. chocolata Yassin & David sp. nov. Scale bars: A–D = 50 µm; E–F = 100 µm..

Fig. 6. Female oviscapts of the ‘D. seguyi species complex’. A–B. D. seguyi Smart, 1945 (MNHN). C–D. D. malagassya Tsacas & Rafael, 1982 (MNHN). E–F. D. curta Chassagnard & Tsacas, 1997 (MNHN). G–H. D. chocolata Yassin & David sp. nov. (MNHN). Scale bars: A, C, E, G = 100 µm; B, D, F, H = 50 µm.