Drosophila bromeliae Sturtevant, 1921

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 : 16-21

Drosophila bromeliae Sturtevant, 1921

Figures 1C ; 2F ; 3 , 4 ; 5A , 8–11A–H

Drosophila bromeliae Sturtevant, 1921: 72 .

DIAGNOSIS: Body yellowish to light brown, of small to average body size for group, thorax ca. 0.90 mm long (0.77–1.07); prescutellar setae large, no small lateral pairs; oviscapt shorter and with apex less acute than in florae , length 4.0× the depth in lateral view. Spermathecal capsule small, short (length approximately equal to width). Aedeagus fairly slender compared to distiphallus length, strongly arched in lateral view, aedeagal angle 99°–118° (mean 108°); distiphallus ovoid to slightly drop shaped in ventral view, with apex narrowed; hypandrium trapezoidal; surstylus with 7–10 blunt prensisetae (mode 9, mean 8.5), ventral setae of surstylus not sclerotized or darkened.

DESCRIPTION: Male: Head: Frons ochraceous yellow to light brown, especially ocellar triangle and fronto-orbital plates, which are also pollinose; margin at ptilinal suture lighter; frontal vittae shiny, finely striate, golden; frontal index 1.06 (0.96–1.12), top to bottom width ratio 1.43 (1.30–1.50). Ocellar triangle between ocelli slightly raised above rest of front, dark brown between ocelli, anterior tip of triangle ca. 0.7× length of frontal length. Bases of ocellar setae lying on tangent between median and lateral ocelli; postocellar setae parallel to slightly convergent, directed slightly posteriad (vs. vertically). Orbital setae dark brown-bronze in color (not black), or1:or3 ratio 0.97 (0.93–1.07), or2:or1 ratio 0.55 (0.53–0.71), postocellar setae 0.44× (0.37–0.51) and ocellar setae 0.69× (0.61–0.78) of frontal length; vt index 1.04 (0.85– 1.12). Vibrissal index 0.44 (0.39–0.58). Face slightly lighter than fronto-orbital plates, especially frontal edge of carina. Carina well developed, thin (greatest width ca. 0.5× that of pedicel), frontal edge flattened, with slight sulcus. Cheek index about 0.08 (0.06–0.15). Eye index 1.43 (1.28–1.64). Occiput light brown, darker between tentorial sutures. Basal antennomeres slightly darker than front or face; arista with 3–4 dorsal and 1–2 ventral branches (4-2 most common), plus small to large terminal fork. Proboscis same color as antenna; palpus lighter, with one apical and one subapical seta.

Thorax length 0.83 mm (0.77–1.07): Scutum evenly ochraceous to very light brown; 6–8 uneven rows of acrostichal setulae. One large pair of prescutellar setae, lengths about 0.46 (0.30–0.60) of posterior dorsocentral setae; setae lateral to prescutellars ranging from ca. 2× length of acrostichals to barely differentiated h index 0.84 (0.70–0.06). Transverse distance of dorsocentral setae 2.66× that of longitudinal distance. Scutellum slightly lighter than scutum; basal scutellars strongly convergent, apical scutellars crossed for nearly 0.5× their length; scutellar seta index 0.85 (0.78–0.92). Pleura approximately same color as scutum, little/no infuscation; sterno index 0.85 (0.65–0.87). Halter with stem lighter, bulb slightly darker than, pleuron. Legs lighter than pleura.

Wing hyaline, veins tan, length 1.72 mm (1.47–2.08), length to width ratio 2.33 (2.19– 2.56). Indices: C, 2.15 (1.9–2.26); ac, 2.40 (2.22–3.00); hb, 0.55 (0.44–0.66), 4-C, 1.09 (0.96– 1.24); 4V, 1.86 (1.54–2.11); 5x, 1.68 (1.39–2.0); M, 0.61 (0.50–0.70). Wing tips slightly pointed, vein R 2+3 straight (not slightly sinuous).

Abdomen dark yellowish, posterior margin of tergites with thin, diffuse, pale brown band interrupted in middle of tergite; bands are thinner anteriorly.

Male terminalia (figs. 8–10): Epandrium with microtrichia, devoid of large setae on dorsal surface; ventral lobe blunt to rounded apically (not pointed), without microtrichia, with 5–7 setae. Cerci with microtrichia, laterally fused to epandrium. Surstylus with microtrichia on outer/lateral surface, with short mesal row of 7–9 prensisetae pegs and 6–7 fine setae. Subepandrial sclerite (not examined). Hypandrium trapezoidal, lateral margins straight (not convex), length 1.07× the width, anterior margin broad to narrow; gonopods fused to hypandrium, apical seta fine. Aedeagus fused to aedeagal apodeme; aedeagus fairly slender compared to distiphallus length, strongly arched in lateral view, aedeagal angle 99°–118° (mean 108°); distiphallus ovoid to slightly drop shaped in ventral view, with one end narrow. Aedeagal apodeme short, keellike.

Female: General morphology similar to males. Female measurements: Frontal index 1.03 (1.00–1.12); top to bottom width ratio 1.42 (1.40–1.55); or1:or3 ratio 0.95 (0.93–0.96), or2:or1 ratio 0.58 (0.53–0.64), lengths of postocellar setae 0.45× (0.41–0.48) and ocellar setae 0.72× (0.67–0.76) of frontal length, vt index 1.01 (0.87–1.16). Vibrissal index 0.48 (0.30–0.73). Cheek index about 0.08 (0.07–0.09). Eye index 1.42 (1.36–1.53). Thorax length 0.97 (0.90–1.04). Lengths of prescutellar setae 0.45× (0.37–0.64) that of posterior dorsocentral setae; h index 0.88 (0.82–0.95). Transverse distance of dorsocentral setae 2.53× (2.35–2.91) of longitudinal distance. Scutellar seta index 0.85 (0.77–0.90), sterno index 0.81 (0.65–1.03). Wing length 2.01 mm (1.60–2.23), length to width ratio 2.40 (2.10–2.65). Wing indices: C, 2.26 (2.00–2.52); ac, 2.49 (2.19–2.66); hb, 0.0.56 (0.53–0.66); 4-C, 0.1.04 (0.98–1.12); 4v 1.82 (1.79–1.92); 5x 1.49 (1.41–1.71); M, 0.0.56 (0.51–0.60).

Female terminalia: Valves of oviscapt rounded at tip (particularly so in holotype), ca. 280 µm long, with 17–20 marginal oviscapt pegs; length ca. 2.5× great width. Spermatheca cup-shaped, height approximately equal to width; basal introvert reaching about 0.7× length of capsule.

TYPE: Holotype, female: labeled: “ Havana, Cuba, Jan. Feb. 1915 ” [printed]/ “TYPE” [printed]/ “ae5497” [handwritten]/ “ Drosophila bromeliae Sturtevant ” [written in Sturtevant’s hand]. The specimen is double mounted with a minuten impaled through the pleura; head is lost; thorax, wings, and legs are intact; abdomen was removed and cleared (dissector unknown) and stored in a corked, glass microvial on same pin as thorax. Oviscapt valves had been separated by a prior dissector, making an intact ventral view impossible; spermathecae lost. In AMNH.

OTHER SPECIMENS: CUBA: “ Havana, Cuba , Jan. Feb. 1915 [printed]/ 1♂ ‘florae’ [written, in A.H. Sturtevant’s hand], dissected by D.A.G. [DBG 14], 1♀ dissected by D.A.G .

[ DBG 15].” Manzo Abajo , 30 km SE Baracoa, 26-II-29, M. v. Tschirnhaus,” 2♀♀ (dissected, DBG 65, 66). All in AMNH . “ DOMINICAN REPUBLIC: Peravia, 19 mi N San José de Ocoa, 3000 ft., 30/VII/91, in morning glory flowers, Grimaldi ,” 2♂♂ (1 dissected, DBG 61), 2♀♀ (1 dissected, DBG 62). In AMNH . “ ECUADOR: Orellana, Reserva Etnica Waorani, 00°39′25/7″S, 76°27′10.8″W, 216m, II-X/1995, Erwin et al., canopy fogging,” 3♂♂ (2 dissected, sample 2072b1, DBG 43; sample 2072b2 DBG 44), 3♀♀ (samples 2074, 2078, 2072b1 [dissected: DBG 42]). In NMNH and AMNH . EL SALVADOR: 1♂, “ Laguna de Zapotitan [printed] 31a.b [handwritten]/ Rep de El Salvador / Dec 3 1953, W.B. Heed ” dissected by D.A.G. ( DBG 7 ) ( AMNH) (from the field notes of W.B. Heed: 31a,b “sweeping at Zapotitán (1500′), swampy forest”); 2♂♂, 2♀♀ “ San Salvador /Rep de El Salvador,” with following handwritten numbers and printed labels: “ Oct 13 1953, W.B. Heed, 9.9” dissected by D.A.G. ( DBG, 5♂), “ Oct 14 1953, W.B. Heed, no. 11.5” dissected by D.A.G. ( DBG 6 , ♂), “ Oct 11 1953, W.B. Heed, no. 5.2” dissected by D.A.G. ( DBG 37 , ♀), “ Dec 10 1953, W.B. Heed, no. 37.6” dissected by D.A.G. ( DBG 36 , ♀) (from the field notes of W.B. Heed for 37.6: “sweeping in barranca just east of [illegible]” and “eggs have only 2 filaments but they are not blunt”); “Rep de El Salvador/ Oct 1953, W.B. Heed /Santa Tecla, 12 km NW” dissected by D.A.G. ( DBG 38♂). All in AMNH . HONDURAS: “ Lancetilla, Honduras / Apr 1954, W.B. Heed ” 4 ♂♂, dissected by D.A.G. (nos. DBG 10, 11, 25, 26), 2♀♀ dissected by D.A.G. ( DBG 27 , 28 ). “ Honduras : Teguelgalpa, No. 27229 2723, VI/I/3/[19]17, F.J. Dyer ” 1♂, dissected by D.A.G. ( DBG 24 ); “ Honduras : Teguelgalpa / No. 27489 1.27507, VII/8/17, F.J. Dyer, 1♀, not dissected. In AMNH. JAMAICA: 1♂ “Jamaica, B.W.I./Falmouth, July 1958 /M Wasserman, W.B. Heed ” dissected by D.A.G. ( DBG 4 ) ( AMNH). In AMNH . MEX- ICO: 1♂ “Merida, Yucatan, Mexico/ W.B. Heed, Sept. 1955 [printed],” dissected by D.A.G. ( DBG 3 ). In AMNH . 2♂♂, “Mexico Quintana Roo, Cozumel S. Miguel, 29 Jan 1981, G.E. Bohart,” both dissected by D.A.G. [DAG 43, 44]. In LACM . NICARAGUA: 1 ♂ “Bluefields, Nicaragua [printed]/ June 1954, W.B. Heed[printed]/55.13 [handwritten]” dissected by D.A.G. ( DBG 1 ) (from the field notes of W.B. Heed for 55.13 “sweeping in second growth woods in back of town”). In AMNH . PANAMA: “ Balboa, Canal Zone, Panama /W.B. Heed , Oct-Nov 1955” 2♂, dissected by D.A.G. ( DBG 8 , 22 ), same 1♀, dissected by D.A.G. ( DBG 32 ). In AMNH .

COMMENTS: This is the most common and widespread species of the group, occurring throughout Central America, the Caribbean, and northern parts of South America ( Ecuador [herein] to northern Brazil [ Schmitz, 2010: Pernambuco, Pará]). However, there is significant variation even in male and female terminalia (see figs. 8–11A–H), and so there may be some morphocryptic species under the present concept of D. bromeliae , ideal for examination using molecular data. Based on the present study the identification of D. bromeliae mentioned in earlier reports can be confirmed, from Cayman Islands, El Salvador, Honduras, Jamaica, Mexico (Yucatán) ( Clayton and Wasserman, 1957; Heed and Wheeler, 1957; Wheeler, 1970). The identification of bromeliae cannot be confirmed from Martinique ( David, 1973), Colombia ( Wheeler, 1970), Puerto Rico, or São Paulo, Brazil ( Hsu, 1949). Although I have not seen any material from the Lesser Antilles, it would not be surprising if D. bromeliae occurred in Martinique, and given its presence in Hispaniola its occurrence in Puerto Rico is expected. Only female specimens were available from Colombia, so species from this country cannot be assessed at present. The presence of D. bromeliae in southern Brazil is doubtful ( Schmitz, 2010).

Like D. bromelioides , this species appears to be very polyphagous. In northern Brazil this species has been reared from flowers in five families ( Schmitz, 2010).

Figures

FIG. 1. Habitus of exemplar species in the bromeliae group. A. Drosophila manni, n. sp. B. D. penispina, n. sp. C. D. bromeliae Sturtevant. D. D. mexiflora, n. sp.

FIG. 2. Heads of exemplar species in the bromeliae group. A. Drosophila penispina, n. sp. (specimen DBG21) B. D. billheedi, n. sp. (DBG 2, holotype). C. D. stylipennis, n. sp. (DBG 12). D. D. mexiflora, n. sp. (DBG 41). Note supernumery left proclinate seta. E. D. manni, n. sp. (DBG 70). F. D. bromeliae Sturtevant (DBG 10). Numbers prefaced by DBG refer to specimens that were dissected.

FIG. 3. Scanning electron micrographs of adult structures of Drosophila bromeliae. A. Face (arrow indicates fine setae on inner surface of pedicel). B. Detail of eye facets and interfacetal setulae. C. Labellum, folded closed. D. Posterior portion of thorax. E. Detail of D. F. Male terminalia. G. Female terminalia. Abbreviations: prso, prescutellar setae.

FIG. 4. Morphological details of Drosophila bromeliae. A. Head, with major setae and other structures labelled. B. Occipital foramen and posterior arms of tentorium. C. Palp. D. Lacinia. E. Cibarium (above, ventral view) and labrum + hypopharynx (below, dorsal view). F, G. Setation of posterior portion of thorax of D. stylipennis, n. sp., DBG 12 (F), and D. penispina, n. sp. DBG 9 (G). Abbreviations: lv, lateral vertical seta; mv, medial vertical seta; oc, ocellar seta; or1–3, orbital setae 1–3 (proclinate, anterior reclinate, posterior reclinate, respectively); poc, postocellar seta; vb, vibrissa.

FIG. 5. Wings of exemplar species in the bromeliae group. A. Drosophila bromeliae Sturtevant (DBG 43: Ecuador). B. D. thurstoni, n. sp. (DBG 35). C. D. penispina, n. sp. (DBG 21). Arrows point to distinctive features: B, to slightly pointed wing tip, short crossvein dm-cu; C, to slightly sinuous vein R2+3. To the same scale.

FIG. 8. Variation in the male genitalia of the most widespread species in the group, Drosophila bromeliae Sturtevant. All lateral views of aedeagus, aedeagal apodeme, gonopod, and full ventral view of distiphallus. All to the same scale. See text for specimen numbers. DBG numbers refer to individual specimen/dissection numbers (full data cited in text).

FIG. 9. Male genitalia of Drosophila bromeliae, continued.

FIG. 10. Variation in the male genitalia of D. bromeliae Sturtevant. A–F. Hypandrium, all to same scale. G–M. Surstylus and ventral lobe of epandrium, all to same scale.