Drosophila prognatha Sturtevant, 1916: 340

Grimaldi, David A., 2018, Hirtodrosophila Of North America (Diptera: Drosophilidae), Bulletin of the American Museum of Natural History 2018 (421), pp. 1-1 : 1-

Drosophila prognatha Sturtevant, 1916: 340 .

DIAGNOSIS: Head, scutum, scutellum yellowish; pleura light, cream colored, with thin light brown band beneath notopleural margin (posterior segment often lacking), faint infuscation beneath wing base; anterior tergites light, infuscate brown, grading posteriad to yellow with narrow bands on posterior margins. Basal flagellomere with long setulae; arista with one ventral, five long dorsal branches; face slightly concave, relatively deep (FD/FW 1.17), with very small carina; frons relatively long (frontal index 1.07); anterior reclinate minute; anterior dorsocentral short (DCindex 0.50); wing short (ThL/WL 0.51), with faint infuscation near apex of Sc vein, vein R 2+3 short (C-index 1.62). Male: Surstylus small, with short vertical row ca. five prensisetae pegs; aedeagus short, stout, partially scaled, with distinctive notch at apex. Female: Oviscapt with ventroapical lobe, vertical row of four dorsal-preapical pegs.

DESCRIPTION: Coloration: Little or no sexual dimorphism in coloration. Head: Frons (including frontal vittae, fronto-orbital plates), face, antennae yellowish (branched portion of arista dark brown, tiny basal articles whitish); area between ocelli dark brown, outside ocelli is yellowish; cheek light yellow, with small light brown areas under eye and at vibrissal angle. Clypeus, palps, proboscis slightly lighter than rest of head, faintly dusky. Thorax: Scutum dark yellowish to light brown, graded from lighter at anterior end to darker posteriad; scutellum similar in coloration. Pleura mostly very light, cream colored, with thin, light brown stripe beneath notopleural suture, faint infuscation beneath wing base usually present. Wing hyaline, no patterning. Legs light yellow; coxae lighter. Abdomen: Tergites 1 and 2 light brown (laterally yellow), tergites 3–4 with light brown transverse band on posterior margin, enlarged in middle on tergites 3 and 4, or most of dorsal surface of tergites 1–4 light fuscous brown, always laterally yellow; all of tergites 5, 6 yellow. Sternites, epandrium, cerci light yellow.

Head: Antenna: Scape largely hidden; pedicel setulose, with 2 setae; basal flagellomere long, tips extended slightly past oral margin, bearing dense, long setulae; arista with 1 ventral, 5 dorsal branches, ventral branch either between dorsal branches 4 and 5 or opposite the latter, branches relatively long, nearly 0.5× length of arista trunk. Eye in lateral view slightly egg shaped, ventral portion much smaller than dorsal portion; interfacetal setulae short, dense, light. Face slightly concave, relatively tall, with concave oral margin; carina very small and short, barely visible between antennae. One pair of vibrissae; subvibrissal setulae much smaller. Frons matte, unicolorous, with borders of fronto-orbital plates, frontal vittae and ocellar triangle barely differentiated, fronto-orbital plates finely striate. Fronto-orbital setae: proclinate approximately same length as posterior reclinate; anterior reclinate very small, ca. 0.25× size of other orbitals, slightly closer to and posterior to proclinate; fronto-orbitals in line with inner vertical. Ocellar seta relatively short, tips barely reaching to proclinate; postocellar setae crossed for ca. 0.3× their length. Inner vertical setae upright, slightly inclinate; outer vertical setae strongly lateroclinate. Proboscis short, retracted into oral cavity, with labellum exposed; labellum small; palp with one, preapical seta.

Head measurements (N = 3): CD/ED 0.14 (0.12–0.16); ED/EW 1.23 (1.20–1.27), FD/FW 1.17 (1.11–1.24), FL/LFW 1.07 (1.03–1.10), HW/ HD 1.25 (1.08–1.35), Ocellar S-index 1.34 (1.18– 1.50), OR1/OR3 0.95 (0.80–1.06), OR2/OR1 0.36 (0.31–0.41), VT-index 1.10 (1.05, 1.15).

Thorax: Setation: Acrostichal setae in 6 rows; anterior dorsocentral short, ca. 0.6× length of posterior dorsocentral; posterior dorsocentral slightly lateral to longitudinal tangent through anterior dorsocentral. Anterior scutellars parallel, slightly shorter than posterior scutellars, lateral pair crossed for ca. 0.3× their length. Two setae on postpronotal lobe; 3 notopleural setae, dorsal one small, fine, posterior one short, thick; 2 supra-alar setae (posterior one long); 2 postalar setae. Anterior katepisternal seta small, ca. 0.5× length of posterior katepisternal. Legs: Fore femur with ventral row of 4 long setae, mid and hind femora without long setae; foretarsus of male without erect, fine setulae on dorsal surface; midtibia with large, ventroapical seta, hind tibia with small, fine, dorso-preapical seta.

Thorax and wing measurements: ThL 0.90 mm (0.76–1.01); DC-index 0.50 (0.43–0.57); S-index 0.47 (0.42–0.56); 4-V index 2.17 (2.07– 2.28); 5-X index 2.10 (2.06–2.18); C-index 1.62 (1.41, 1.78); hb-index 1.75 (1.60–1.96); ThL/WL 0.51 (0.49, 0.52); WL/WW 2.16 (2.14, 2.18).

Male Terminalia: Epandrium evenly arched; with microtrichiae overall except for ventral lobes; ca. 5 setae laterally, plus ca. 5 setae on ventral lobe; ventral lobe of epandrium relatively short, not quite reaching to ventral level of surstylus. Cercus with microtrichia and setae; ventral margin with sparse, fine, short setulae. Surstylus simple, relatively small, with minute dorsal lobe just above prensisetae; short vertical row 5 prensisetae pegs dorsally, ventrally with ca. 10 stout setae. Hypandrium well developed, anterior margin rounded; posterior margin with medial lobe; paraphysis with microtrichia on mesal surface, 1 large apical seta; distal lobe slightly wrinkled. Aedeagus short, stout, approximately same length as aedeagal apodeme, largely membranous, with small, sparse scales basally on dorsal surface; apex with distinctive median notch.

Female Terminalia: Oviscapt with ventroapical lobe, bearing 3 pegs at apex; short vertical row of 4 preapical pegs; ventral margin with row of 6 small pegs. Oviprovector very well developed, scales large, well developed, shingled. Spermatheca dome shaped, with narrow collar of fine annulations; introvert about 0.5× length of capsule.

TYPE: Holotype, male (not dissected) Puerto Rico: Adjuntas, June 8–13, 1915, “TYPE” (red, printed label), “ Am. Mus. Nat. Hist. Dept. Invert. Zool. No. 24149, Drosophila prognatha Sturtevant ” (written label, in Sturtevant’s hand). In AMNH.

OTHER SPECIMENS EXAMINED: USA: Florida: Alachua Co., Gainesville, Possum Creek Pres., 19/VII/2007, on fungus, S. Bybee, 1♀, 3♂ (1 dissected, no. 13). Puerto Rico: Adjuntas, June 8–13, 1915, [“F3960b” on back of label], 6♀, 3♂ (dissected, no. 60), paratypes (all AMNH)

COMMENTS: I dissected several specimens from Sturtevant’s paratype series from Puerto Rico, which perfectly match the Florida specimens. I also find that this species is remarkably similar to H. morgani (Mourão, Gallo, Bicudo) , based on the original description and illustrations by Mourão et al. (1967), as well as the detailed redescription and illustrations of male terminalia by Vilela and Bächli (2004). Hirtodrosophila morgani is known from central to southern Brazil ( Robe et al., 2014: states of Bahia, Paraná, Rondônia, and Santa Catarina) and may even occur in Argentina (Misiones) ( Vilela and Bächli, 2004). In one study from Brazil it was found breeding primarily in Auricularia (Auriculariaceae) ( Valer et al., 2016). Interestingly, ecological niche modeling based on the Brazilian records ( Robe et al., 2014) predicts the occurrence of H. morgani throughout southern Brazil, Paraguay, northern Argentina, eastern Bolivia and Peru, western Ecuador, a small portion of central Venezuela, much of Central America and Hispaniola. I dissected prognatha -like male specimens from Belize, Panama, Colombia, French Guiana, and southern Venezuela, which had a uniform genital morphology (there were also several cryptic species). It appears that true H. prognatha is widespread at the very least throughout the Caribbean, Central America, and probably northern South America, but I need to examine Brazilian specimens to better assess their identity.