Drosophila subfunebris Stalker and Spencer, 1939

Grimaldi, David A., 2022, The Drosophila funebris Species Group in North America (Diptera: Drosophilidae), American Museum Novitates 2022 (3988), pp. 1-28 : 17-21

Drosophila subfunebris Stalker and Spencer, 1939

Figs. 1C , 2C , 4C , 5D ; 6E, J ; 7E , 8F , 9D

Drosophila subfunebris Stalker and Spencer, 1939: 108 . Subsequent refs: Patterson, 1943 (redescription, internal reproductive organs, chromosomes).

DIAGNOSIS: The most distinctive species of the group that is native to North America: anterior reclinate orbital seta lateral to proclinate or nearly so (vs. posterolateral to proclinate in other species). Male genitalia: aedeagus with broad, winglike lateral lobes; hypandrium distinctly constricted in middle; shaft of aedeagus thick in lateral view; male cercus with 6 (vs. 4–5) spines. Oviscapt lightly sclerotized, relatively thick in lateral view, with ca. 30 small marginal pegs.

DESCRIPTION: (N = 4 specimens, all measured from type series). Largest native funebris - group species, ThL 1.39 (1.25–1.48); wing length, 1.96 mm (1.90–2.03).

HEAD: significantly broader than deep, HW/HD 1.40 (1.38–1.44). Eye dull red, with dense ommatrichia, shape ovoid, ED/EW 1.27 (1.25–1.32). Frons short, FL/LFW 0.60 (0.58–0.63), wider dorsally, UFW/LFW 1.32 (1.27–1.36); frons and face dull, dark yellow, antennae very light brown; frontal-orbital plates and ocellar triangle slightly shiny. Proclinate orbital twice the length of anterior reclinate, OR 1 /OR 2 2.1 (2.0–2.6), proclinate significantly shorter than posterior reclinate, OR 1 /OR 3 0.61 (0.55–0.66); contralateral proclinates slightly divergent, posterior reclinates slightly divergent. Inner vertical slightly lateral to tangent running through ipsilateral proclinate and posterior reclinate. Anterior reclinate directly lateral to proclinate, distance of separation equal to diameter of socket. Vertical setae equal in size, VT-index 0.98 (0.96–1.00); inner vertical strongly inclinate, outer vertical almost directly posterior to inner vertical. Postocellars strong, convergent; ocellar setae significantly longer than postocellars, Ocellar S-Index 1.30 (1.24–1.36). Antennal pedicel with 2 strong setae (1 proclinate, 1 lateroclinate); aristae [broken on all specimens]. Carina broader than in other species, CL/CW 4.39 (3.9–5.4), laterally declivous (not steep as in macrospina and limpiensis ), more protruding. Vibrissa significantly longer than subvibrissa, vibrissa index 0.77 (0.71–0.84). Clypeus shiny, short, squared. Palp with apex brown, base yellow; dorsal margin flat, ventral margin convex with 3 strong setae. Labellum with 10 pseudotracheae. Cheek short, ED/CD 7.2 (6.1–8.4); occiput brown.

THORAX: Scutum and scutellum dark yellowish to very light brown, slightly shiny. Acrostichals in 8 rows. Short row of 2–3 acrostichals anterior to anterior dorsocentral are faintly larger than others (similar for acrostichals anterior to transverse suture). Two long postprontal setae, lower seta slightly larger than upper one, h-index 0.88 (0.77–0.93). Three large notopleurals, 2 anterior ones longest. Anterior supraalar seta short, posterior one very long. Two large katepisternal setae, posterior one significantly longer than anterior, S-index 0.60 (0.57– 0.63). Dorsocentral setae well developed, anterior seta significantly shorter than post. dc, DCindex 0.61. Scutellar setae nearly equal in length, Scut-index 0.93 (0.91–0.95); anterior scutellars parallel, posterior pair crossing for 0.25 to 0.5× their length. Legs light yellow. Fore femur with 3–4 long, fine ventral setae, 2 lateral ones; male protarsus without longer, curved setulae. Midtibia with long, thick ventroapical seta, smaller dorsal-preapical seta; hind tibia with 1 fine, preapical-dorsal seta.

Wing entirely hyaline, of moderate length relative to body size WL/ThL 1.96 (1.90–2.03), relatively broad WL/WW 2.18 (2.10–2.24); C-index 2.91 (2.80–3.01); hb-index 1.94 (1.78– 2.15); 4V-index 1.37; distance of crossvein dm-cu from wing margin nearly equal to length of xvein, 5X-index 1.10 (1.06–1.20).

ABDOMEN: Pigmentation with moderate sexual dimorphism. Male: tergites 3–6 entirely dark, shiny brown; tergites 1 and 2 with dark yellow medially; tergite 7 light brown, epandrium dark yellowish. Female: tergites 3–4 with dark yellow bands on anterior margin, tergite 5 with paramedian yellow areas; tergites 6 and 7 dark brown; tergite 8, paraprocts and oviscapt dark yellow.

MALE TERMINALIA: Epandrium short, lightly sclerotized, devoid of microtrichia and setae (except 3 short, stiff setae on ventral lobe), dorsolateral phragma very well developed. Cerci projecting, without microtrichia; setae abundant and long (lengths greater than cercal width), posteroventral margin with 6 heavily sclerotized spines: narrow one dorsally, separated by gap from others about 2× width of spine; 5 ventralmost spines adjacent (no spaces between bases), 3 most ventral spines short and stout. Surstylus broadly rounded ventrally, with 9 prensisetae pegs, ~11 thick setae; no microtrichia on surstylus. Hypandrium lightly sclerotized, slightly longer than aedeagal apodeme, with lateral constrictions. Gonopods lightly sclerotized, each with one larger and one very fine seta. Aedeagus with shaft short, very broad in lateral view; preapically with pair of broad, winglike lobes having finely serrate lateral margins; distal lobes with coarse, spinelike teeth on apical margin and row of fine serrations on mesal margin. Aedeagal apodeme well sclerotized, slightly shorter than aedeagus. Ejaculatory apodeme relatively small, bent at right angle.

FEMALE TERMINALIA: Oviscapt not heavily sclerotized; short, broad in lateral view (depth 0.3× the length), apex rounded, not pointed. Oviscapt with ~30 small pegs along margin, plus 3 pegs on dorsolateral portion of valve. Spermatheca faintly pear shaped (narrower at base), sclerotized; introvert long, ~0.8× length of capsule, apex of introvert with pair of small lobes.

TYPES: Neotype (designated herein), male (dissected): United States: California / Pasadena, 1949/ Neotype Drosophila subfunebris det. D. Grimaldi, 2022. In AMNH .

SPECIMENS EXAMINED: United States: California: Pasadena , 1949 [no further information]. 5M, 3F (1 of each sex dissected), in AMNH .

DISTRIBUTION: Known only from the type series.

COMMENTS: Stalker and Spencer (1939) mentioned isofemale cultures of D. subfunebris that were maintained for over a year, originally collected in Pasadena, California (V/1937, and XI/19- 28/1936)—from which the “type and gonotypes” were taken—and at “Camp Rincon, San Gabriel Mountains, California (IV/24/1937)” (~34.4114°, -117.9206°). The Pasadena culture whose behavior was studied by Spieth (1952) and Ewing (1979) presumably was one of those made by Spencer. None of these existed by 2016 in the NDSC when it was at Univ. California, San Diego. The only specimens of this species of which I am aware is a small series of five males and three females in the AMNH from the Pasadena location, from which I am designating the neotype. A thorough search for type holdings of Spencer was made (AMNH, NMNH), including inquiries to the College of Wooster, Ohio, where Spencer was a professor. Typical for species described by Spencer, there are no designated types or other archived specimens. I collected in the San Gabriel Mountains in June 2017 at Wrightwood, California (34.4037°, -117.7243°) but did not find this species.

Figures

FIG. 1. Heads, frontal views, of native North American species of the Drosophila funebris group. A. D. limpiensis (ex: type locality: Limpia Canyon, Texas). B. D. macrospina (ex: Rochester, NY). C. D. subfunebris (ex: type series: Pasadena, CA). D. D. trispina (ex: type series: Earp, CA). To the same scale.

FIG. 2. Heads, lateral views, of native North American species of the Drosophila funebris group. A. D. limpiensis (ex: Limpia Canyon, TX). B. D. macrospina (ex: Piqua, OH). C. D. subfunebris (ex: Pasadena, CA). D. D. trispina (ex: Earp, CA). To the same scale.

FIG. 4. Epandria (male) of native North American species of the Drosophila funebris group; posterolateral views (to same scale). A. D. limpiensis (ex: Limpia Canyon, TX). B. D. macrospina (ex: Magazine Mtn., AR). C. D. subfunebris (ex: Pasadena, CA). D. D. trispina (ex: Earp, CA).

FIG. 5. Male genitalia of native North American species of the Drosophila funebris group, ventral views (to same scale). A. D. limpiensis (ex: Limpia Canyon, TX). B. D. macrospina (ex: St. Catherine’s Island, GA). C. D. macrospina (ex: Rochester, NY). D. D. subfunebris (ex: Pasadena, CA). E. D. trispina (ex: Earp, CA).

FIG. 6. External details of male terminalia, A–G: Cercal spines, right lateral views; H–K: Surstyli, lateral views. All to same scale. A. D. limpiensis (ex: Limpia Canyon, TX). B. D. limpiensis (ex: Patagonia, Arizona). C. D. macrospina (ex: New Orleans, LA). D. D. macrospina (ex: Piqua, OH), dashed line indicates spine sometimes missing. E. D. subfunebris ex: Pasadena, CA). F. G. D. trispina (ex: Earp, CA), G. showing right cercus with one less spine. H. D. limpiensis (ex: Limpia Canyon, TX). I. D. macrospina (ex: New Orleans, LA). J. D. subfunebris (ex: Pasadena, CA). K. D. trispina (ex: Earp, CA).

FIG. 7. Aedeagi with aedeagal apodemes, ejaculatory apodemes (B, D, E), lateral views (all to same scale). A. D. macrospina (ex: Magazine Mtn., AR). B. D. macrospina (ex: Rochester, NY). C. D. limpiensis (Limpia Canyon, TX). D. D. trispina. E. D. subfunebris.

FIG. 8. Detail of apices of aedeagi (ventral views) of native North American species of the D. funebris group (all to the same scale). A. D. limpiensis. B. D. macrospina (ex: New Orleans, LA). C. D. macrospina (ex: Piqua, OH). D. D. macrospina (ex: Missouri). E. D. trispina. F. D. subfunebris.

FIG. 9. Female terminalia (oviscapts, spermathecal capsules, and minutely scaled oviprovector membrane [internal]) of North American species of the D.funebris group (all to same scale).A. D. funebris (introduced). B. D.limpiensis. C. D. macrospina (spermatheca of limpiensis and macrospina is identical). D. D. subfunebris. E. D. trispina.