Delhi sands flower-loving fly Rhaphiomidas terminatus abdominalis Class: Insecta Order: Diptera Family: Apioceridae Dudek and Associates Species Accounts Status: Federal: Endangered State: None Data Characterization The life cycle of the Delhi Sands flower-loving fly make it difficult to study the life history and requirements of this species. Although recent studies have been conducted on the Delhi Sands flower- loving fly and related species, further studies and information are needed regarding food requirements, microhabitat needs, survivorship, dispersal requirements, socio-spatial requirements, and effectiveness of habitat restoration efforts. All four records within the U.C. Riverside data base hold x and y coordinate points, and therefore are considered precise enough for conservation planning purposes. All records were collected between 1995 and 1996. Habitat and Habitat Associations R. t. abdominalis is tied to fine, sandy soils, often with wholly or partly consolidated dunes referred to as the "Delhi" series (USFWS 1993). The fly if typically found in relatively intact, open, sparse, native habitats with less than 50% vegetative cover (USFWS 1997). The vegetation type, desert sand-verbena series includes Eriogonum fasciculatum, Croton californicus, Lotus scoparius, and Oenothera californica (Sawyer and Keeler-Wolf 1993). In most cases, Eriogonum fasciculatum, Heterotheca grandiflora, and Croton californicus are associated with the presence of Delhi sands flower-loving fly (Ballmer1989, USFWS 1997). In addition, Ambrosia acanthocarpa, Amsinkia intermedia, Eriastrum sapphirinum, Eriogonum thurberi, Lessingia glandulifera (USFWS 1993), and Eriastrum filifolium (Cazier 1985) have also been found in association with R. t. abdominalis. Biogeography The Delhi Sands flower-loving fly is restricted (endemic) to the Colton Dunes (Delhi soil series) that once covered over approximately 40 square miles in northwestern Riverside and southwestern San Bernardino counties in southern California (USFWS 1997; USDA 1980, 1990) in irregular patches. The historic range of the Delhi Sands flower-loving fly likely extended over much of this area. All known extant populations of the Delhi Sands flower-loving fly occur within an 8 to 11-mile radius of each other within the counties of Riverside and San Bernardino (USFWS 1993; 1997) straddling Interstate 10 in the vicinity of Colton and Rialto, Riverside and San Bernardino Counties ranging from Colton to Mira Loma. Nearly all of the remaining habitat is privately owned and distributed largely within the vicinity of Colton, Rialto, Fontana, Ontario, and the Prado-Mira Loma area, with the most contiguous and highest quality habitat in Colton. Range The distribution of the Delhi Sands flower-loving fly within Riverside is limited to the northern portion of the County in the vicinity of Mira Loma, Jurupa, and the Agua Mansa area. The Delhi series soils extend east-west along Interstate 60 within the County of Riverside. Key Populations in Planning Area Although few areas of Riverside County have been surveyed for R. t. abdominalis, there are known localities in the Jurupa Hills area and within the Aqua Mansa Industrial Center. The historic range also extends west into the Mira Loma area. Known populations occur adjacent to the Prado/Mira Loma area of Riverside County. For purposes of species recovery, all known populations and recoverable vacant soils are considered key areas within the western Riverside planning area. Biology Genetics: Taxonomic studies by Sinclair, et al. (1993), Woodley (1989), and Yeates (1994) have recently included the genus Rhaphiomidas into the family Mydidae. This genus includes 19 species and 5 sub- species in southwestern United States and Mexico (Rogers and Mattoni 1993; Cazier 1985). Much study conducted on museum specimens (Coquillett 1891; Townsend 1895; Cazier 1941) placed the species into R. episcopus, R. mellifex, R. terminatus, and finally into R. abdominalis. In 1985, Cazier revised the genus and determined that R. abdominalis was a sub-species of R. terminatus. No genetic analysis studies have been conducted. Diet: The only observed foraging events have involved a few brief nectaring events on California buckwheat flowers (USFWS 1997). Rogers and Mattoni (1993) were unable to determine what the larval stages ate. It is unclear whether the early stages are herbivores, detrivores, or carnivores (USFWS 1997). R. t. abdominalis has a long proboscis which is used for extracting nectar from flowers (USFWS 1993). Daily Activity: The adult stage can only be found on the surface for a few days during the late summer, however the larval stages are present year-round in the soil. The larval stage may last for two or more years (USFWS 1997). Rogers and Mattoni (1993) found that the females became active at 10:00 hours, regardless of cloud cover and became inactive at 18:00 hours unless ovipositing. Survival: There is no information regarding survival. Socio-Spatial Behavior: There is no information regarding socio-spatial behavior. Reproduction: The single reproductive period for R. t. abdominalis occurs in August and September, when the adults emerge from pupae and take flight. The males are more active than the females, probably searching for mating opportunities (USFWS 1993). The males out number the females 2:1. Eggs are deposited in sand and may lay at least 50 eggs (Ballmer 1989). Oviposition locations may be tied to certain vegetation characteristics; similarly to the genus Apiocera (Cazier 1985). Larvae develop and may spend one to two years under the surface of the sand. They develop into pupae when fully developed and emerge (USFWS 1993). Dispersal: There is no information regarding dispersal. Threats widespread over the Colton Dunes, the Delhi Sands flower-loving fly now is restricted to 12 known populations, of which 11 are small and highly vulnerable to extinction. Virtually all populations occur in small, isolated habitat patches surrounded by incompatible land uses. Extensive surveys for R. t. abdominalis by Ballmer (1989) and others (USFWS 1993, 1997) indicate that it now only occupies 2.5% of the total Delhi sands available. The greatest threat to the Delhi Sands flower-loving fly is loss and degradation of its habitat. Urban development, agricultural uses, sand mining, and invasion by exotic species. Dumping of cow manure and trash have also caused significant loss and modification of the species' habitat. Other threats include off- road vehicles and collecting. Special Biological Considerations The Delhi Sands flower-loving fly is endemic to the Colton Dunes (Delhi series soils) in areas that contain suitable conditions for the subterranean early stages, adult nectar sources, and adult feeding, breeding, and perching areas. Soil and climatic conditions, and other ecological and physical factors contribute to the maintenance of open sand areas within the species range. Since the Delhi Sands flower-loving fly is endemic to the Colton Dunes and is strongly associated with the Delhi soils series, protection of this habitat is imperative for conservation of this species. Conservation needs will require protection and management of occupied and restorable habitat, removal of exotic vegetation, and reduction of other threats to the species and/or its habitat. Literature Cited Ballmer, G. 1989. A petition to the United States Fish and Wildlife Service (to list the Delhi Sands flower- loving fly as endangered). Riverside, California. Cazier, M. A. 1941. A generic review of the family Apioceratidae with a revision of the North American species (Diptera-Brachycera). Amer. Mid. Nat. 25:589-631. _____ 1985. A revision of the North American flies belonging to the genus Rhaphiomidas (Diptera: Apioceridae). Bull. Amer. Mus. Nat. Hist. 182(2):181-263. Coquillett, D.W. 1891. A new Rhaphiomidas from California. West Amer. Sci. 7(56):84-86. (Cited in Cazier 1985). Hickman, J.C., ed. 1993. The Jepson manual: higher plants of California. Univ. of Calif. Press, Berkeley and Los Angeles. 1,400 pp. Rogers, R. and M. Mattoni. 1993. Observations on the natural history and conservation biology of the giant flower loving flies, Rhaphiomidas (Diptera: Apioceridae). Dipterological Research 4(1-2):21-34. Sawyer, J., and T. Keeler-Wolf. 1995. A manual of California vegetation. California Native Plant Society. Sacramento, California. Sinclair, B. J., J. M. Cumming, and D. M. Wood. 1993. Homology and phylogenetic implications of male genitalia in Diptera-lower Brachyera. Ent. Scand. 24:407-342. Townsend, C. H. T. 1895. On the Diptera of Baja California, including some species from adjacent regions. Proc. Calif. Acad. Sci., Ser. 2:601-607. (cited in Cazier 1985). U. S. Fish and Wildlife Service. 1993. Endangered and threatened wildlife and plants; determination of endangered status for the Delhi Sands flower-loving fly. Federal Register 58 (183):49881-49887. _____ 1997. Delhi Sands flower-loving fly (Rhaphiomidas terminatus abdominalis) recovery plan. U.S. Fish and Wildlife Service, Portland, OR. 51pp. U. S. Soil Conservation Service. 1971. Soil Survey: western Riverside County. U.S. Gov. Printing Office, Washington, D.C. 188 pp. _____ 1980. Soil survey of San Bernardino County southwestern part, California. U.S. Gov. Printing Office, Washington, D.C. Woodley, N. E. 1989. Phylogeny and classification of the "Orthorrhapous" Brachycera. Pages 1371-1395. In J.F. McAlpine and D.M. Wood. Manual of nearctic Diptera vol. 3. Agriculture Canada 32, Ottawa, Ontario, Canada. Yeates, D. H. 1994. The cladistics and classification of the Bombyliidae (Diptera:Asiloidea). Bull. Amer. Mus. Nat. Hist 219:1-191.