Drosophila mojavensis baja Mettler, 1963

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 : 933-934

Drosophila mojavensis baja Mettler, 1963

( Figure 3B )

Drosophila mojavensis Patterson, 1943:158

Diagnosis

Drosophila m. baja can be distinguished from the other subspecies by the shape of the aedeagus ( Figure 3B ). Internal margin of aedeagus/external margin of aedeagal apodeme index52.04 (1.36–2.30; n 520); ventral margin of aedeagus/wide aedeagal apodeme index55.30 (4.08–5.89). Dorsal margin of aedeagus in the anterior part has a depressed curve that is less pronounced than in D. m. sonorensis; aedeagus tip is pointed and looks like a spine (some individuals appear to have two small spines).

Distribution and host cactus

Baja California peninsula and the islands of the western Gulf of California ( Figure 1 , but see remarks below). Host cactus: pitaya agria ( Stenocereus gummosus ).

Remarks

In Mettler’s (1963) brief description, no mention is made of type specimens or a type locality. Flies assigned to D. m. baja by Mettler (1963) were collected over a wide geographic area of northwestern Mexico, including the states of Baja California Sur (La Paz and Mulege´), Baja California (near Cabo San Miguel on the Gulf of California) and mainland Sonora (Sonoita and Magdalena). Here we are restricting the definition of D. m. baja to include only the peninsular populations (with the possible exception of flies from the San Felipe region in northeastern Baja California) and those from islands in the western gulf; the Sonoran populations are here assigned to D. m. sonorensis (see following account). In the absence of evidence that types were ever designated, and to avoid confusion in future taxonomic studies of the D. mojavensis subspecies group, we have designated a neotype of Drosophila mojavensis baja from La Paz, Baja California Sur (see Material examined) in accordance with Article 75 of the Code of the International Commission of Zoological Nomenclature (ICZN). This designation is necessary to clarify the taxonomic status of D. m. baja and to fix a type locality.

The subspecies assignment of flies from the San Felipe region in northeastern Baja California needs to be confirmed with molecular markers and examination of genitalia, but some evidence suggests that D. m. sonorensis, or possibly D. m. mojavensis , might be found there. Richardson et al. (1977) reported that the Adh-2 S allele was fixed in flies from San Felipe, suggesting that they belonged to D. m. sonorensis, although number of individuals analyzed was not given (San Felipe was not sampled in the Adh study of Zouros (1973)).

Material examined

Neotype. Male: Baja California Sur ( Mexico), La Paz, February 2001, L. Matzkin, deposited at the San Diego Drosophila Stock Center collection at the University of California, San Diego, La Jolla, California (acquisition no. 527 from laboratory culture MJBC 113 started from flies collected on Stenocereus gummosus ). Neoparatypes (same collection data as neotype): 14 males and 15 females deposited at the San Diego Drosophila Stock Center collection (acquisition nos. 528–541 (males) and 542–556 (females)); 10 males and 10 females deposited at the Smithsonian Diptera Collection, United States National Museum of Natural History ( USNM), Washington, DC. External measurements were conducted on 20 males and 20 females from laboratory culture MJBC 113 ; internal (genitalia) measurements were conducted on 20 males.

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.