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

Amir Yassin,Arnaud Suwalski,Lala H Raveloson Ravaomanarivo

doi:10.5852/ejt.2019.532

Abstract

The ‘D. bakoue species complex’ Rafael, 1984 (‘D. montium species group’ Da Lage et al., 2007) comprises seven Afrotropical species. Using complete mitochondrial genome sequences and detailed morphological analysis, we revised the phylogenetic relationships between these species including two new ones. We found the ‘D. bakoue species complex’ to be a junior synonym of the ‘D. seguyi species complex’ Lachaise, 1971 and its seven species polyphyletic. We thus classified the species into three complexes, the ‘D. seguyi species complex’ comprises D. seguyi Smart, 1945, D. malagassya Tsacas & Rafael, 1982, D. curta Chassagnard & Tsacas, 1997 and D. chocolata sp. nov., the new ‘D. tsacasi species complex’ comprises D. tsacasi Bock & Wheeler, 1972 and D. seguyiana Chassagnard & Tsacas, 1997, and the new ‘D. vulcana species complex’ comprises D. vulcana Graber, 1957 and D. mylenae sp. nov. Drosophila bakoue Tsacas & Lachaise, 1974 could not be assigned to any of the defined complexes. The two new species are endemic to Madagascar and we report the presence of D. seguyi and D. curta in Mayotte and Madagascar, respectively. The results hence represent a significant step towards understanding the diversity and evolution of this species group in Africa and the islands of the Western Indian Ocean.

Highlights

The ‘D. montium species group’ Da Lage et al, 2007 is the largest clade of the subgenus Sophophora Sturtevant, 1939
We extended our taxonomic scope by analyzing sequences of the ~650 bp-long DNA barcoding region of the cytochrome oxidase subunit 1 (COI) mitochondrial genes for the African species of the ‘D. montium species group’ published in Li et al (2012), Chen et al (2013) and Prigent et al (2017), and of the ~1350 bp-long of the nuclear Amylase-related (Amyrel) gene from Da Lage et al (2007) using MEGA7 and MrBayes as mentioned above
The twenty-three Afrotropical species of the ‘D. montium species group’ were classified under four complexes: ‘D. bakoue species complex’ (7 spp.), ‘D. bocqueti species complex’ (3 spp.), ‘D. nikananu species complex’ (4 spp.) and ‘D. megapyga species complex’ Lachaise & Chassagnard, 2001 (3 spp.), with six species not classified under any complex (Yassin 2018)

Summary

Introduction

The ‘D. montium species group’ Da Lage et al, 2007 is the largest clade of the subgenus Sophophora Sturtevant, 1939. The earliest attempt to classify the Afrotropical species into species complexes was made by Lachaise (1971) who erected the ‘D. seguyi species complex’ Lachaise, 1971 for four species from Ivory Coast. The second complex was suggested to be called ‘D. seguyi species complex’ by Tsacas & Lachaise (1974) and comprised five species with no dorsal pegs on the surstylus and with distinct anterior parameres: D. bakoue Tsacas & Lachaise, 1974, D. greeni Bock & Wheeler, 1972, D. seguyi, D. tsacasi Bock & Wheeler, 1972 and D. vulcana Graber, 1957. Chassagnard et al (1997) excluded D. greeni from the ‘D. bakoue species complex’, while adding to it two species: D. curta Chassagnard & Tsacas, 1997 and D. seguyiana Chassagnard & Tsacas, 1997

Methods

Results

Conclusion