Drosophila mexiflora, Grimaldi, 2016

Grimaldi, David A., 2016, Revision of the Drosophila bromeliae Species Group (Diptera: Drosophilidae): Central American, Caribbean, and Andean Species, American Museum Novitates 2016 (3859), pp. 1-56: 27-31

publication ID

http://doi.org/ 10.1206/3859.1



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scientific name

Drosophila mexiflora

new species

Drosophila mexiflora   , new species

Figures 1D View FIG , 2D View FIG , 13–15 View FIG View FIG View FIG

DIAGNOSIS: Moderate size (thorax length 0.94 mm), body brownish; arista with 3–4 dorsal and 1–2 ventral branches; prescutellar index ca. 0.50, no smaller lateral pairs; aedeagus short and thick, length 6.8× greatest width, barely curved in lateral view (aedeagal angle 129°–142°, mean 133°); distiphallus large, length 0.4× that of aedeagus; surstylus with 8–11 slender prensisetae, ventral setae sclerotized; hypandrium U-shaped to trapezoidal. Oviscapt unique in the group: short (180 µm), with only 8–9 oviscapt pegs (pegs 1–3 and 12–20 lost); spermatheca similar to that of D. bromeliae   .

DESCRIPTION: Male: Head: Front of head light brown on ocellar triangle and fronto-orbital plates, with faint bluish pollinosity; frontal vitta narrow, golden and shiny, finely striate; frontal margin near ptilinal suture a dull tan; frontal index 1.01 (0.96–1.14), top to bottom width ratio 1.47 (1.42–1.53). Ocellar triangle raised slightly above rest of front, area between ocelli dark brown, anterior corner extended to ca. 0.7× length of front. Orbital setae brownish bronze (not black), or1:or3 ratio 0.93 (0.78 [ Jamaica specimen no 16]–1.00), or2:or1 ratio 0.62 (0.47–0.81 [ Jamaica specimen 16]), postocellar setae 0.42 (0.36–0.48) and ocellar setae 0.69 (0.62–0.78) of frontal length; vt index 1.01 (1.00–1.05). Base of ocellar seta lying just outside tangent between median and lateral ocelli; postocellar setae parallel and directed slightly posteriad in Oaxaca specimens; convergent in Nayarit specimens. Vibrissal index ca. 0.40 (0.20–0.53). Face slightly lighter than front; carina well developed, frontal surface flattened and very narrow (width ca. 0.7× that of pedicel), sulcus faint to absent. Cheek index 0.09 (0.07 [ Jamaica specimen 16]– 0.11). Eye index 1.41 (1.28–1.63). Occiput light brown. Basal antennomeres slightly darker than front, especially pedicel; arista with 3–4 dorsal and 1–2 ventral branches, plus terminal fork. Proboscis light brown; palpus lighter, with one apical and one subapical seta.

Thorax length 0.94 mm (0.68 [ Jamaica specimen 16]–1.08). Scutum dark yellowish to light brown, pollinose; approximately 8 very uneven rows of acrostichal setulae; one large pair of well-developed prescutellar setae, 0.51× (0.36–0.57) length of posterior dorsocentral setae, with one to two pairs of smaller, lateral prescutellars slightly differentiated from acrostichals; h index 0.79 (0.64–0.87). Transverse distance of dorsocentral setae 2.82× (2.46–3.27) that of longitudinal distance. Scutellum slightly lighter than scutum, also pollinose; basal scutellars convergent, apical scutellars convergent to crossing; scutellar seta index 0.85 (0.76–1.02). Pleura slightly darker than scutum, with very slight, brownish infuscation, sterno index 0.77 (0.73–0.83). Halter similar color to pleura, legs lighter than pleura or scutum.

Wing hyaline, veins light brown, length 1.92 mm (1.42 [ Jamaica specimen 16] –2.19), length to width ratio 2.38 (2.23–2.61). Indices: C, 2.12 (1.90–2.41); ac, 2.33 (2.10–2.52); hb, 0.55 (0.51–0.60), 4-C, 1.09 (0.98–1.29); 4V, 1.88 (1.75–1.86); 5x, 1.50 (1.22–1.63); M 0.58 (0.53– 0.63). Wing tip slightly pointed; Vein R 2+3 very slightly sinuous, not straight, section of C basal to Sc break with 3–4 thicker spinules.

Abdomen overall light brown, posterior margin of tergites with thin, faint, diffuse brown band.

Male terminalia (figs. 13, 14). Epandrium with microtrichia on dorsal portion but without setae; ventral lobe not extended beyond ventral margin of surstylus, apex blunt (but not rounded), with 8–10 setae, without microtrichia. Cerci fused laterally to epandrium. Surstylus with microtrichia, medial margin with row of 8–11 long, pointed prensisetae pegs, ca. 8 ventral setae that are moderately to distinctly sclerotized. Hypandrium shape varying from trapezoidal to U-shaped. Gonopods fused to hypandrium and aedeagal apodeme, with fine, short, apical seta. Aedeagus short and thick, length 6.8× greatest width, barely curved in lateral view (aedeagal angle 129°–142°, mean 133°); distiphallus large, length 0.4× that of aedeagus. Aedeagal apodeme short and keel shaped.

Female: General morphology similar to males. Measurements: Thorax length 0.58 mm. Frontal width index 1.41; frontal index 0.96. or1:or3 ratio 0.94, or2:or1 ratio 0.56, postocellar setae 0.77× and ocellar setae 0.71× the frontal length, vt index 1.10 Vibrissal index 0.66. Eye index 1.41. Prescutellar setae 0.50× the posterior dorsocentral setae; h index 0.86. Transverse distance of dorsocentral setae 3.66× the longitudinal distance. Scutellar seta index 0.91, sterno index 1.00. Wing length 2.10 mm, length to width ratio 2.36. Wing indices: C, 1.96; ac, 2.75; hb, 0.54; 4-C, 1.19; 4v 1.93; 5x 1.55; M, 0.61.

Female terminalia: Valves of oviscapt rounded at tip, ca. 180 µm long, with only 8–9 oviscapt pegs (pegs 1–3 and 12–20 lost); spermatheca structure and shape similar to that of D. bromeliae   , height 0.79–1.03× the width; basal introvert reaching about 0.8× length of capsule.

TYPE: Holotype, ♂: “ MEXICO: Nayarit, San Blas area , 16–21 III/83, W.J. Hanson. ” Type is point mounted, in good condition, abdomen removed and cleared, genitalia dissected by D.A.G., and stored in glass microvial on same pin as specimen. In LACM.  

OTHER SPECIMENS: Paratypes, all from MEXICO: 2 ♂♂ “ MEXICO: Oaxaca, 60 mi. S. Oaxaca, IX/6–IX/7/47 1807.1 [field notebook number], M.R. Wheeler / F.A. Cowan,” both dissected by D.A.G. (nos. 22, 39). From M.R. Wheeler’s field notes for 1807.1: “Flies captured in flowers of a wild sp. of Hibiscus   ...@ 60 mi south of the city of Oaxaca, Oax., Mexico...on am 9-7, flowers in bloom evening before + on which flies were taken are now collapsed and shriveled,” dissected ( DBG 42). 1♂: same data as holotype (dissected, DBG 39). In AMNH   . 2♂♂, “ MEXICO: Nayarit, San Blas area, 16-21 III/83, W.J. Hanson ” (printed label), dissected ( DBG 41, 42); 11♀♀, “Mexico: Nyarit, San Blas LeBajada , 6-21/III/83, W.J. Hanson ” (printed labels), 3 dissected ( DBG 80–82); 1♂ “ MEXICO: Jalisco, 18 mi N Barro de Navidad, 23/VIII/1973, Hanson, Schwartz” (printed label), dissected ( DBG 45). In LACM   ; 1♂, 1♀ in AMNH   . Two other male specimens are not being designated as paratypes (see below): “ JAMAICA, Ocho Rios, BWI/ W.B. Heed, M Wasserman July 1958.” ( AMNH). “ COSTA RICA: Heredia, IX 1963, N.H.L. Krauss collector” ( AMNH, dissected, DBG 83)   .

ETYMOLOGY: From Mexico, country of type series, and - flora (L., flower), referring the flower-visiting habit of the species.

COMMENTS: The short, thick aedeagus of D. mexiflora   is similar to that of D. billheedi   and D. sevensteri   , n. spp., and the Brazilian species D. aguape   , but it is less curved in lateral view and the distiphallus differs as shown in fig. 13. Also, the surstylus of D. mexiflora   has 8–12 slender, pointed prensisetae and ventral setae that are sclerotized; versus 7–9 shorter, more blunt prensisetae in the other species and ventral setae that are not sclerotized. The following features differ with bromeliae   : aedeagus distinctly shorter and shaft thicker in lateral view, aedeagal angle 129°–142° (vs. bent at nearly a right angle in bromeliae   ), ventral setae of the surstylus moderately to distinctly sclerotized.

Female genitalia confirm the species distinction of D. mexiflora   , with a reduced number of oviscapt pegs unique for the group. Females in the bromeliae   group typically have 15 or more oviscapt pegs; mexiflora   has only 8–9. This reduction is due to loss of pegs 1–3 and pegs 12 and higher.

The Jamaica specimen (DBG 16) is distinctively smaller than the Mexican specimens (ca. 0.68× the thorax length, 0.70× the wing length), and it differs from the Mexican specimens in orbital seta ratios (see description above). As a unique specimen the consistency of these differences cannot be evaluated, and since the proportions and shape of the aedeagus are identical to those of the Mexican specimens the conservative approach is to include these into one species until additional data may prove otherwise. Male genitalia of the Costa Rica specimen (DBG 83) is nearly identical to that of the Mexican specimens except that DBG 83 has the distiphallus more drop-shaped in full ventral view, and prensisetae shorter.


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