Drosophila mojavensis mojavensis Patterson and Crow, 1940

Pfeiler, E., Castrezana, S., Reed, L. K. & Markow, T. A., 2009, Genetic, ecological and morphological differences among populations of the cactophilic Drosophila mojavensis from southwestern USA and northwestern Mexico, with descriptions of two new subspecies, Journal of Natural History 43 (15 - 16), pp. 923-938 : 929-932

Drosophila mojavensis mojavensis Patterson and Crow, 1940

( Figures 2 and 3A )

Drosophila mulleri mojavensis Patterson and Crow, 1940:251

Drosophila mojavensis Patterson and Wheeler, 1942:95 ; Patterson, 1943:158

Diagnosis

Drosophila m. mojavensis can be distinguished from the other subspecies by the shape of the aedeagus ( Figure 3A ). Internal margin of aedeagus/external margin of aedeagal apodeme index51.0 (0.99–1.01; n 530); ventral margin of aedeagus/wide aedeagal apodeme index53.7 (3.65–3.92). Tip of aedeagus with a small pointy protuberance; dorsal and ventral aedeagus margins almost form an isosceles triangle. Aedeagus ventral margin almost straight with a small protuberance in the middle zone.

Redescription

Male. Head. Front brownish; frontal length 0.32 (0.30–0.34) mm; frontal index50.83 (0.76–0.88). Frontal triangle pale brown, more or less distinct. Ocellar triangle slightly prominent and lighter than front, pollinose. Interfrontal setulae in ‘‘V’’ shape. Frontal vittae brownish; orbital plates wider at the or1 level, almost a pointed shape. Orbital setae black, or2 just slightly posterior to or1; or1/or3 ratio50.90 (0.76–1.07); or2/or1 ratio50.60 (0.56–0.68); vibrissal index50.51 (0.41–0.61). Face brownish. Carina broad below and sulcate, central area similar colour as vittae; distal lateral sections light brown. Cheek index ca. 5.70–9.86. Eye red; eye index51.17 (1.11–1.25). Occiput yellowish, brown above foramen. Antennae tannish brown, pedicel slightly darker, third joint darker; arista with three dorsal, two ventral, and about four small inner branches, plus terminal fork. Proboscis yellowish, clypeus brownish. Palpus pale yellow with about three strong setae along external ventral margin. Thorax. Length: 1.01 (0.98–1.04)mm. Mesonotum light brownish-yellow; setae arising from brown spots; eight rows of acrostichal setulae. Upper/lower postpronotal setae (h index)51.20 (1.19–1.20); anterior/posterior dorsocentral setae (dc index)50.63 (0.60–0.65). Scutellum dark brownish with margin slightly clear. Basal setae slightly convergent, apical scutellar convergent; basal/apical scutellar setae (scut index)50.82 (0.73–0.90). Pleura brownish, shining, with a narrow, dark brown stripe from upper margin of katepisternum to below procoxa. Faint darker brown stripes, one visible along upper margin, and a second stripe on the middle part of anepisternum; this strip prolonged faintly to the anepimeron. Anterior/posterior katepisternal setae (sterno index)50.72 (0.64–0.80), median katepisternal seta about 52–61% of the anterior one. Haltere yellow with slightly brownish colouration on anterior side of knob. Legs yellow, with a faint brownish postbasal band on tibia which it is darker on hind leg. Procoxa and all fifth tarsal segments slightly darker than the rest of the legs; preapical setae on all tibiae, apical seta on mesotibia. Abdomen ( Figure 2A ). Pale yellow; apical band on tergites well defined in dorsal area with interruption between sides. On the upper margin of the lateral area, apical band curves slightly and expands as a diffuse extension to almost touch the margin of the anterior tergite. Background colour in lateral area brownish-yellow, diffuse; most of the margin in lateral areas from tergites 1–4 covered by a dark irregular spot; colour of lateral area spots lighter than apical band; colour gradually disappears from ventral to dorsal area; spot almost completely disappears at posterior margin of tergite 5. Testes yellow with 2.5 inner and 3 outer coils. Wings. Hyaline, veins brown. Apex of subcostal break slightly black with two well-developed setae. Third costal section with heavy bristles on its basal third. Crossveins clear. Wing length 1.70 (1.60–1.80)mm, length to width ratio51.82 (1.73–1.88). Indices: Costa (C index)52.91 (2.69–3.06), C-III/C-IV (ac index)52.27 (2.00–2.57), C-III/M-III (4C index)50.92 (0.80–1.05), M-IV/M-III (4v index)51.81 (1.67–1.91), CuA (apical section)/dM-Cu (5x index)51.26 (1.00–1.44), CuA (apical section)/M-III (M index)50.48 (0.43–0.53), Basal R 4+5 /M-III (prox. X index)50.67 (0.64–0.71). Genitalia. Cerci with few microtrichose, many long setae, and fused anteriorly to epandrium. Epandrium barely microtrichose on dorsal area; three to five setae on the apical margin in the medial section; ventral lobe enlarged and bare, with filament-like setae, forming a rounded toe that partially overlaps surstylus laterally. Surstylus not microtrichose; 9–11 peg-like prensisetae almost rounded on tip, with the two anterior setae slightly larger and pointed; three to four inner setae larger than prensisetae; seven to eight outer setae. Cerci barely microtrichose; hypandrium slightly longer than epandrium. Aedeagus fused to aedeagal apodeme ( Figure 3A ). Aedeagal apodeme upper half smaller than aedeagus. Ventral rod almost twice as long as width of aedeagal apodeme.

Female. Identical to male, except as follows. Abdomen similar to male except lateral light area on tergite 5 diffuse, darker than male ( Figure 2B ). Wings. Wing length 1.78 (1.62–1.87)mm, length to width ratio52.01(1.93–2.05). Indices: Costa53.20 (2.45– 3.43), C-III/C-IV52.34 (2.13–2.57), C-III/M-III50.86 (0.77–1.03), M-IV/M- III51.64 (1.51–1.74), CuA (apical section)/dM-Cu51.19 (1.00–1.38), CuA (apical section)/M-III50.52 (0.46–0.58), Basal R 4+5 /M-III50.80 (0.70–1.00). Genitalia. Valve of oviscapt distally rounded, ventrally almost straight, with ca. 6 distal and 12–13 marginal, peg-like, mostly roundish-tipped, outer ovisensi1la; inner ovisensi1la: four thin, trichoid-like, distally positioned, and one long, straight, subterminal.

Distribution and host cactus

Mojave Desert (southern California to northwestern Arizona; Figure 1 ). Host cactus: barrel cactus ( Ferocactus cylindraceus ).

Remarks

Referring to many newly described species of Drosophila , including D. m. mojavensis, Patterson (1943) commented that type specimens are widely scattered in private collections and museums. Whether a holotype was designated is not stated in either Patterson and Crow (1940) or Patterson (1943), but a ‘‘cotype’’ (either a syntype or paratype) of D. m. mojavensis from Mesquite Springs, Death Valley, California is deposited in the American Museum of Natural History, New York. We did not examine the ‘‘cotype’’.

Material examined

External and internal (genitalia) measurements were conducted on 30 males and 12 females from laboratory culture ANZA406 started with flies from California ( USA), near Borrego Springs, Anza-Borrego Desert State Park , San Diego County, April 2006, collected by L. K . Reed and T. A . Markow. Voucher specimens (all from isofemale line culture ANZA406-4 ) : 10 males and 12 females deposited at the San Diego Drosophila Stock Center collection at the University of California, San Diego, La Jolla, California (acquisition nos. 461–470 (males) and 471–482 (females)) ; 10 males and 10 females deposited at the Smithsonian Diptera Collection, United States National Museum of Natural History ( USNM), Washington, DC .

Figures

Figure 1. Map showing approximate geographic distribution of the four subspecies of Drosophila mojavensis in southwestern USA and northwestern Mexico.?5unconfirmed subspecies at San Felipe, Baja California. Numbers show localities where flies used for laboratory cultures were collected: (1) Mojave; (2) Baja; (3) Sonora; (4) Catalina (see ‘Materials and methods’ for details).

Figure 2. Lateral view of abdominal pattern in Drosophila m. mojavensis. (A) Male; (B) female.

Figure 3. Photographs showing lateral views of the aedeagus and aedeagal apodeme in the four subspecies of Drosophila mojavensis. (A) D. m. mojavensis; (B) D. m. baja; (C) D. m. sonorensis; (D) D. m. wrigleyi.