Drosophila (Sophophora) affinis Sturtevant, 1916

Grimaldi, David A., 2024, The Drosophila (Sophophora) obscura species group in the Americas (Diptera: Drosophilidae): review, revisions, and three new species, American Museum Novitates 2024 (4015), pp. 1-44 : 13-14

Drosophila (Sophophora) affinis Sturtevant

Figures 4A , 7A , 9A ; 11A, B ; 14A

Drosophila affinis Sturtevant, 1916: 334 .

DIAGNOSIS: A small, very common species in eastern North America, thorax color varying from light brown to black-brown ( Werner and Jaenike, 2017: 83); carina very narrow, short; male sex comb with ta 1 usually with 4–5 teeth (ranging from 4–7 [ Sulerud and Miller, 1966), ta 2 with 1 slender tooth; ta 1 distinctly shorter (0.88×) than ta 2; base of inner ventral epandrial lobe with furrows, no microtrichia.

TYPE: Holotype: ♂ + puparium: bred banana [written] / Kushla, Ala [bama] IV.25.15 AH Sturtevant / TYPE Drosophila affinis Sturt. [red label] / Amer. Mus. Nat. Hist. Dept. Invertebrates No. 24134. In AMNH. The adult and its puparium are mounted on separate points on the same pin.

SPECIMENS EXAMINED: Besides type (above), the following material (all in AMNH): UNITED

STATES: ALABAMA: Kushla, Ala. VI.13.14, A.H. Sturtevant / Paratype (1). GEORGIA: large series, Georgia , Liberty Co., St. Catherine’s Is. , 11-20/IV/88, Grimaldi (two dissected: ASG 28♀, ASG 29 ♂) .

MAINE: Mount Desert Isle , ME 29 June-3 July 1982, J. Jaenike (7) . MASSACHUSETTS: 5 mi W Ipswich, Mass / July 1948 M.R. Wheeler (8) . NEW JERSEY: Morris Co., Pompton Plains, vi.10.2012, D. Grimaldi , on Lysurus borealis fungus (rotten fish smell) (17); N Brnswck [New Brunswick] NJ / Metatype VI/20 [Sturtevant coll.] (9) . NEW YORK: New York [City], X.12.14, A.H. Sturtevant / Metatype (1); Chenango Valley St. Park, IV /15-V/6, 1982, D.A. Grimaldi (6); Trumansburg, VI /16- 22/83, D. Grimaldi, coll. (22) . NORTH CAROLINA: Alum Cave Bluffs, Great Smoky Mountains , VII/18-22/82; Clingman’s Dome , Great Smoky Mountains , VII/18-22/82, J. Jaenike (11); Raleigh, VIII/3/82, J. Jaenike (3) . TEXAS: Houston , Harris Co., White Oak Bayou, VI /20/83, J. Jaenike (7) .

VERMONT: Mad Brook Farm, E. Charleston, Orlean Co., VT VII/15-25/82, D. Grimaldi (4) .

DISTRIBUTION: The eastern half of North America , including prairie states; from Texas, Florida, and the Gulf coast in the south, to Maine, southern Ontario and Québec in the north, west to Minnesota ( Miller, 1958; M. Miller et al., 2017) .

COMMENTS: The main breeding sites of this very abundant species have not been determined. These flies are attracted to a variety of substrates and will breed in low levels in such varied host plants as decaying spadices of skunk cabbage ( Symplocarpus foetidus : Araceae ) ( Grimaldi and Jaenike, 1983), and fruits of mayapple and huckleberry (respectively, Podophyllum peltatus : Berberidaceae ; and Gaylussacia spp. , Vaccinium spp. : Ericaceae ) ( Carson and Stalker, 1951). I have also found them attracted to Lysurus borealis fungus ( Phallaceae ), which has the smell of rotten fish (full record given above), but it wasn’t determined whether they were breeding in the fungus. The species has not been found to breed in mushrooms, despite all the efforts in breeding flies from various macrofungi (e.g., Werner and Jaenike, 2017).

An interesting aspect of the natural history of D. affinis is their attraction in significant numbers to the flowers of pawpaw ( Asimina triloba : Annonaceae ) ( Martin, 2021; Goodrich et al., 2023). Various drosophilids are the most abundant visitors to the flowers, and D. affinis is the most abundant fruit fly visitor. The tree has a distribution throughout eastern North America similar to that of D. affinis . The flowering of pawpaw occurs in the early spring, the flowers smelling yeasty and fermenting; it is unknown whether D. affinis is a significant pollinator of this plant, whether they breed in its flowers and fruits, or possibly even both.

Figures

FIG. 4. Frontal view of heads of representative species of the affinis subgroup. A. D. affinis, male. B. D. chibcha, n. sp., male holotype (ASG 05); C. D. tolteca, male (ASG 23); D. zapoteca, n. sp., male holotype (ASG 20). Note differences in development of the facial carina compared with faces in figure 3.

FIG. 7. Oviscapts and spermathecae (lateral views) of species in the affinis subgroup, with apical details for three species. A. D. affinis (ASG 28); B. D. athabasca (ASG 30); C. D. azteca (ASG 15); D. D. chibcha, n. sp. (ASG 17); E. D. dobzhanskii (ASG 33); F. D. narragansett (ASG 11); G. D. tolteca (ASG 24).

FIG. 9. Protarsal male sex combs (tarsomeres ta1 and ta2, and ta3 for D. chibcha from Peru) of species in the affinis subgroup. A. D. affinis (ASG 29); B. D. algonquin (ASG 32); C. D. athabasca (ASG 31); D. D. azteca (ASG 13: San Franciso, CA); E. D. azteca (ASG 06: Leticia, Colombia); F. D. chibcha, n. sp. (ASG 04: Zurqui, Costa Rica); G. D. chibcha, n. sp. (ASG 05: Las Alturas, Costa Rica); H. D. chibcha (ASG 07: Rancho Grande, Venezuela); I. D. chibcha (ASG 08: Wayqecha, Peru); J. D. narragansett (ASG 10); K. D. olmeca (ASG 25); L. D. tolteca (ASG 23). All to the same scale.

FIG. 11. Epandria (male tergite VIII) and associated structures in representative species of the affinis subgroup. A. D. affinis (ASG 29); B. D. affinis, detail of A; C. D. azteca (ASG 13); D. D. chibcha, n. sp. (ASG 05).

FIG. 14. Hypandrium, aedeagus and other appendages of representative species of the affinis subgroup (ventral views). The valves of the aedeagal sheath and the pair of hypandrial lobes are highlighted in color; the postgonites are not. A. D. affinis (ASG 29) (hypandrial lobes hidden); B. D. athabasca (ASG 31); C. D. algonquin (ASG 32); D. D. chibcha, n. sp. (ASG 05), with detail of aedeagal valves of ASG 05 (above), and ASG 08 (below). All to the same scale except details of D. chibcha.