california desert ants

Genus LIOMETOPUM Mayr

Liometopum occidentale Emery
Figures 191-194

     Liometopum microcephalum var. occidentale Emery, 1895:330; o _.
     Liometopum apiculatum var. occidentale: Wheeler, 1905:324; o.
     Liometopum occidentale: Wheeler, 1917:522; o _. M. Smith,
1947:590; pl.16 fig.61; o. Creighton, 1950:339; o. Wheeler and Wheeler, 1973:100; o. Allred, 1982:486. Gulmahamad, 1995:84-85.

     RANGE: Southern Oregon, California at low to moderate elevations; Baja California.

     DESERT RECORDS. Map 8. Inyo Co.: Eureka Valley, Feb. 1978 (DG; CDFA); Paiute Canyon, 3500'?5000', Inyo Mts., 17 June 1976 (DG; LACM); Willow Creek, 2400', Inyo Mts., 3 May 1976 (DG; LACM); Willow Creek, 4500', Inyo Mts., 16 Sept 1976 (DG; LACM). Los Angeles Co.: Big Rock Wash at Palmdale Blvd., 1 Apr 1972 (J.P. & K. E. Donahue; LACM). San Bernardino Co.: Victorville, 2700', 8 Apr 1949 (W. D. Pierce; LACM); same locality, 28 May 1938 (C. M. Dammers; LACM); Yermo, 1935', 7 Sept 1952 (RRS; LACM). Riverside Co.: Smithwater Canyon, JTNP, 6 Aug 1960 (M. Know, E. L. Sleeper; LACM); Palm Canyon, 3 Apr 1925 (P. H. Timberlake; LACM); Whitewater Canyon, 14 Oct 1994 (RRS; LACM). San Diego Co.: Grapevine Cyn., 4.5 mi W Hwy. 78, 2220 ft., 2 Apr 1997 (R. A. Johnson; RAJC).

     DISCUSSION. This species enters the desert from adjacent chaparral zones along stream courses. It is commonly associated with oaks and cottonwoods. The Mojave River bottom in the vicinity of Victorville, with an extensive grove of cottonwood trees, supports a large population of L. occidentale.
      Liometopum occidentale generally occurs at elevations ranging from sea level to about 4800 feet in California where it nests in the ground under stones. It may occasionally be found nesting in hollow trees or under roots of trees. Nest chambers are often subdivided by a network of paper-like material which the ants make by mixing soil, plant detritus and a mandibular secretion (Creighton, 1950). A carton nest of L. occidentale was figured by Gulmahamad (1995) who also discussed the occurence of nests of this species in man-made structures.
     The closely related L. apiculatum Mayr seems to tolerate a number of myrmecophiles, but none are known for this species. However, Disney (1982) has recorded the scuttle fly, Pseudacteon californiensis Disney (Diptera: Phoridae), as a parasite of L. occidentale; the female flies oviposit into the gaster of the host ant. Reproductive females of L. occidentale have been found in the nests and collected at lights in May. We also have seen an alate female taken at black light during August.