Drosophila starki, 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 : 48-50

Drosophila starki , new species

Figure 22

DIAGNOSIS: Small (0.73 mm thorax length), light brown species with very thin carina and highly distinctive male genitalia: hypandrium narrow, length 1.2× the width; aedeagus straight

(not arched), base very narrow; aedeagus apex bulbous, with extensive membrane and flat ventral lobe bearing pair of spines.

DESCRIPTION: Male: Head. Frons light brown (yellowish on anterior margin); frontal vitta thin, lighter than rest of front, golden, finely striate; frontal index 1.15, top to bottom width ratio 1.65. Ocellar triangle slightly raised above rest of front, dark brown, anterior apex meeting ptilinal suture. Orbital setae dark brownish bronze (not black), or1:or3 ratio 1.00, or2:or1 ratio 0.77, ocellar seta 0.74× the frontal length (postocellar and vertical setae lost on unique specimen); base of ocellar seta slightly outside of tangents between median and lateral ocelli. Vibrissal index 0.25. Face same color as front. Carina very thin, width ca. 0.5× that of antennal base; edge slightly flattened, no sulcus. Cheek index about 0.09. Eye index 1.32. Occiput slightly darker than rest of head. Basal antennomeres light brown (anterior surface of pedicel darkest); arista with 4 dorsal and 2 ventral branches, plus large terminal fork. Proboscis ochre to light brown; palpus slightly lighter, with one apical and one subapical seta.

Thorax length 0.73 mm. Scutum light brown, slightly shiny; 6 rows of long acrostichal setulae; 1 pair of long prescutellar setae, 0.62× the posterior dorsocentral setae; setae lateral to prescutellars not differentiated from acrostichals; h index 0.79. Transverse distance of dorsocentral setae 2.45× the longitudinal distance. Scutellum dull, same color as scutum, basal scutellars (lost in unique specimen); scut index (not determinable; scut setae lost). Pleura light, infuscate brown, sterno index 0.66. Halter infuscate. Legs light, diffuse light brown near middle of femora and tibiae.

Wing hyaline, veins light brown, length 1.70 mm, length to width ratio (not determined). Indices: C, 2.00; ac, 2.75; hb, 0.59, 4-C, 1.15; 4V, 1.86; 5x, 1.57; M, 0.58. Wing tip rounded, vein R 2+3 straight (not slightly sinuous).

Abdomen color overall light, infuscate brown, posterior margins of tergites darker and diffusely grading into light areas.

Male terminalia (fig. 22): Epandrium with microtrichia, without setae except for those on ventral epandrial lobes; ventral lobe blunt (not pointed), without microtrichia, with ca. 5 setae. Cerci microtrichose, fused laterally to epandrium. Surstylus with microtrichia over most of outer surface, with row of 10 small, peglike prensisetae, about 8 other, fine setae. Subepandrial sclerite (not examined). Hypandrium narrow, length 1.2× greatest width, with slightly flared anterior margin. Gonopods slender in lateral view, not fused to hypandrium, with short, fine apical seta. Aedeagus nearly straight, not arched, fused to aedeagal apodeme; in lateral view base very narrow, gradually expanded distad to bulbous apex; distiphallus bulbous, with extensive apical membrane and flat lobe bearing pair of apical spines directed anteriad. Aedeagal apodeme fairly large, keel shaped.

Female: Unknown.

TYPE: Holotype (unique specimen), ♂: “ DOMINICAN REPUBLIC: La Altagracia, mouth of Rio Chavón, 29/II/92, Grimaldi and Stark , sweeping along shores.” Type is point mounted, in fair condition (some orbital, all scutellar setae are lost); abdomen was removed and cleared, genitalia dissected by D.A.G. (dissected, DBG 59), dissection and left wing stored in a glass microvial on the same pin as specimen. In AMNH.

ETYMOLOGY: Patronym, for Julian Stark, dipterologist, colleague, and friend of the author, who collaborated in fieldwork in the Dominican Republic and Costa Rica.

COMMENTS: The male genitalia of the type and only specimen of this species are unique for the bromeliae group: the aedeagus is short and straight, with a very slender base; the distiphallus is bulbous, with extensive membrane and a ventral shelf bearing a pair of spines; gonopod and surstylus are relatively small, and the aedeagal apodeme is large. Moreover , it was not collected at flowers, but by sweeping the muddy shores of a river in eastern Dominican Republic .

Figures

FIG. 22. Male genitalia of Drosophila starki Grimaldi, n. sp. (DBG 59). A. Lateral view of aedeagus, aedeagal apodeme, and gonopod. B. Full ventral view of distiphallus. C. Surstylus and ventral lobe of epandrium. D. Hypandrium.