Drosophila (Sophophora) mylenae David & Yassin, 2019

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 : 21-22

Drosophila (Sophophora) mylenae David & Yassin sp. nov.

urn:lsid:zoobank.org:act:B64DA5B1-4F29-456B-B75E-0E84DFB3DA98

Figs 1–2 , 8 C–D, 9B, D, F

Diagnosis

Male abdominal tergites T5 and T6 with a distinct dark brown stripe expanding in the middle and fainting towards the margins ( Fig. 8B ); hypandrium broad with a short anterior phragma; outer paraphases posterior margin not curved; aedeagus pilosity broad at tip ( Fig. 9B, D ); female abdominal tergites T2–T4 with a diffuse pale region on the antero-distal margins, T5 with distinct dark stripe ( Fig. 8D ); oviscapt fourth posterior peg-like outer ovisensillum on the same axis with the third and fifth ovisensilla, with anterior ovisensilla short and thick ( Fig. 9F ).

Etimology

A species dedicated to Mylène Dauvergne, co-collector of the type strain.

Type material

Holotype

MADAGASCAR • ♂; Nosy Be ; 13°20′ S, 48°15′ E; Jul. 2008 (ex-laboratory strain Feb. 2017); J.R. David and M. Dauvergne leg.; MNHN.

Paratypes

MADAGASCAR • 9 ♂♂, 10 ♀♀; same collection data as for holotype; MNHN .

Other material

MADAGASCAR • 5 ♂♂, 5 ♀♀; same collection data as for holotype; ZUAC .

Description

Male

HEAD ( Fig. 8C ). Frons pale brown, frontal length 0.35 mm; frontal index = 1.00, frontal tapering ratio = 1.29. Frontal triangle concolorous; ocellar triangle slightly darker, about 43% of frontal length. Orbital plates about 86% of frontal length. Orbital setae black, distance of or3 to or1 = 50% of or3 to vtm, or1 / or3 ratio = 1.33, or2/or1 ratio = 0.38, postocellar setae = 29%, ocellar setae = 50%, vibrissal index = 1.00. Face white. Carina prominent, narrow. Cheek index about 12.00. Eye red, eye index = 1.15. Antennae whitish. Arista with four dorsal, three ventral branches, plus terminal fork. Proboscis brown.

THORAX ( Fig. 8C ). Length 1.13 mm. Scutum mid brown, shining, darker before scutellum, six rows of acrostichal setulae. H index = 1.17. Transverse distance of dorsocentral setae 200% of longitudinal distance; dc index = 0.61. Scutellum dark; scut index = 0.80. Pleura slightly darker, shining. Legs whiteyellow, sex combs on protarsomeres 1 and 2, with about 18 and 13 peg-like setae, respectively. Wing dark, length 1.54 mm, length to width ratio = 2.08. Indices: C = 1.93, ac = 3.06, hb = 0.62, 4C = 1.72, 4v = 3.03, 5x = 0.56, M = 1.13, prox. x = 0.72. Haltere brown.

ABDOMEN ( Fig. 8C ). Yellow, tergites T2–T4 with a diffuse brown posterior stripes, tergites T5 and T6 pale with small posterior stripes.

TERMINALIA ( Figs 3C , 9B, D ). Epandrium pale brown, with 6 setae, the lower most being particularly long; ventral lobe with 5–7 bristles. Cercus pale brown; cercal ventral lobe yellow, partially separated from cercus, with a series of three strong, curved spines on the inner margin, and smaller spines along the ventral, outer and dorsal margins, larger dorsally. Surstylus with a regular row of five short, stout peg-like prensisetae, and a ventromedial cluster of prensisetae, the innermost pointing dorsally. Hypandrium yellow, slightly longer than broad, with a pointed medial posterior extension bearing two short, divergent thick bristles; posterior margin microtrichose with long fine hairs. Outer paraphyses large, ovoid, transverse, bearing three minute setulae. Inner paraphyses almost as long as aedeagus, swollen medially, tapering and incurved medioposteriorly. Aedeagus hirsute, broad at tip, subapically narrowed. Aedeagal apodeme yellow, broadened laterally.

Female

HABITUS ( Fig. 8D ). Similar to male, but with no sex combs on protarsi and with abdominal tergites brown.

TERMINALIA ( Fig. 9F ). Valve of oviscapt mediodorsally mostly membranous, posteriorly rounded, ventrally slightly concave, with no discal and twelve marginal, peg-like, pointed-tipped, short and thick ovisensilla on the outer surface and one long, straight, subterminal and three tiny (microscopic) trichoidlike ovisensilla on the inner surface.

Distribution

Madagascar (endemic).

Remarks

Drosophila mylenae sp. nov. resembles D. vulcana in the shape of the male periphallic structures (compare Fig. 3C with figure 1 in Rafael 1984) and the female ovipositor ( Fig. 9 E–F) as well as in the abdominal pigmentation pattern of females being darker than males ( Fig. 8 ), which is rare among drosophilids. However, they differ in the degree of abdominal pigmentation for both sexes and in multiple phallic structures ( Figs 8–9 A–D). The two species show a very low mitogenomic divergence of 0.5% ( Figs 1–2 ). However, on the nuclear gene Amyrel they are quite distinct ( Fig. 2 ), with an overall nuclear genome-wide divergence of 2.35% (Yassin, in prep.).

Drosophila mylenae sp. nov. was only collected in the littoral forest on Nosy Be. It is absent from material collected from the inland, humid forests of Madagascar, i.e., Antananarivo, Mandraka, Andasibe and Ranomafana. It is also absent from Mayotte or other islands of the Western Indian Ocean. 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. 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.