Drosophila mojavensis sonorensis Castrezana, 2009

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 : 934-935

Drosophila mojavensis sonorensis Castrezana , new subspecies

( Figure 3C )

Drosophila mojavensis baja Mettler, 1963 (in part)

Drosophila mojavensis sonora Hocutt, 2000

Type material

Holotype. Male : Sonora ( MEXICO), Guaymas, June 1999, L. Matzkin, deposited at the San Diego Drosophila Stock Center collection at the University of California, San Diego, La Jolla, California (acquisition no. 557 from laboratory culture MJ 122 ) . Paratypes (same collection data as holotype) : 15 males and 10 females deposited at the San Diego Drosophila Stock Center collection (acquisition nos. 558– 572 (males) and 573–582 (females)) ; 10 males and 10 females deposited at the Smithsonian Diptera Collection , United States National Museum of Natural History ( NMNH), Washington, DC .

Diagnosis

Drosophila m. sonorensis can be distinguished from the other subspecies by the shape of the aedeagus ( Figure 3C ). Internal margin of aedeagus/external margin of aedeagal apodeme index51.21 (1.19–1.27; n 515); ventral margin of aedeagus/wide aedeagal apodeme index54.33 (4.26–5.16). Compared to D. m. mojavensis , ventral margin of aedeagus in D. m. sonorensis is larger with stronger protuberances; dorsal margin of aedeagus has a depressive curve resulting in a narrow aedeagal tip.

Distribution and host cactus

Sonora and Sinaloa, Mexico to southern Arizona, USA ( Figure 1 ). Host cactus: organ pipe ( Stenocereus thurberi ), except in the region of El Desemboque, Sonora where pitaya agria ( Stenocereus gummosus ) is also utilized.

Remarks

High frequencies of the Adh-2 S allele in flies from islands adjacent to Sonora in the eastern Gulf of California, including Tiburón Island ( Richardson et al. 1977; Heed 1978), suggest that they belong to D. m. sonorensis. Also, Etges (1993) found D. mojavensis on pitaya agria in the El Desemboque region of mainland Sonora, about 5km from Tiburón Island, which from their size and behaviour were typical of the mainland population, D. m. sonorensis.

Material examined

External measurements were conducted on 20 males and 20 females from laboratory culture MJ 122; internal (genitalia) measurements were conducted on 15 males.

Etymology

Subspecies name suggested by Hocutt (2000) was sonora for the state of Sonora, Mexico, the geographic centre of its distribution, here changed to sonorensis to follow ICZN recommendations .

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 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.