ON THE INTRODUCED ANT QUADRISTRUMA EMMAE ( HYMENOPTERA : FORMICIDAE ) IN FLORIDA 1

The Old World tropical ant Quadristruma emmae is reported from 28 counties in southern and central Florida, where it occurs in a variety of man-modified and natural, xeric and mesic habitats. Based on its habitat requirements, it is expected to colonize sheltered urban habitats in the southwestern United States. A captive colony caught and consumed entomobryid Collembola. This species, along with the neotropical exotic Strumigenys eggersi, are common throughout southern Florida, and may have had local effects on some northern species of dacetines of the genus Smithistruma whose ranges extend into central and southern Florida, but these exotic dacetines are not expected to endanger native species of ants. Three males collected in flight traps are believed to represent this species, based on size, and the structure of the mandible and forewing. The ant Quadristruma emmae(Emery) (Fig. 1 ) is a tramp species known from Florida, the West Indies (specimens reported from the Bahamas: San Salvador, North Andros, New Providence; Cuba; Puerto Rico; and U.S. Virgin Islands: St. Thomas), Africa, India, the Seychelles, Malaysia, Indonesia, New Guinea, Australia, NewHebrides, the Philippines, Guam, and Hawaii (Bolton 1983). It is clearly native to the Old World tropics, where its only congener occurs. Brown (1954) suggested that the species originated in Africa as a lineage derived from the Strumigenys rogeri Emery species group. Quadristruma emmae is the only ant in Florida (or the United States) whose antennae have only four segments. Other character states useful for identification are the bowed jaws with two apical teeth, the large spoon-shaped hairs with discoid tips on the head (Fig. 1), and the small size (length of worker about 1 .4 mm, length of female about 1 .7 mm). Outside the U.S., the distinction between Quadristruma and the large, diverse genus Strumigenys depends primarily on the reduced number of antennal segments in the former genus, and Quadristruma may eventually be subsumed into Strumigenys (Brown 1954). There is no possibility of confusing Q. emmaewith any Florida species of Strumigenys. The purpose of this note is to describe the range and habitat preferences of Q. emmae in Florida, present some information on its diet and colony composition, consider its possible ecological impact on native species, and describe specimens that are believed to be the previously unknown male. DISTRIBUTION ANDECOLOGY Quadristruma emmae is presently confined to southern and central penin2 Archbold Biological Station, P.O. Box 2057, Lake Placid, FL 33862. 3 207 Adams Ave. NE, Lake Placid, FL 33862. ENT. NEWS1 1 0( 1 ): 13-21, January & February, 1 999 14 ENTOMOLOGICAL NEWS Figure 1 . Quadristruma emmae, worker. sular Florida. The site records in Fig. 2 are from a study of litter-inhabiting ants from throughout Florida, including hundreds of Tulgren funnel extractions from sites north of the sites shown in Fig. 2. Quadristruma emmaewas not found by Johnson in his exhaustive study (1986) of the ants of Alachua County. The distribution of this species in Florida, as well as its world distribution (Bolton 1983), suggest that it will not become a common species in the colder parts of Florida, or elsewhere in the U.S. It is, however, an abundant species in southern Florida areas that are centers of the nursery trade, and it is likely to be transported all over the southeastern U.S. and eventually into the Southwest, where it might establish populations in protected microclimates, especially in urban areas. It may already occur in cities in southern Texas, Arizona, NewMexico, and California, all states with such varied and exciting natural habitats for ants that their anthropogenic habitats may receive less attention. In southern Florida, it has been found in most xeric and mesic sites that have been intensively sampled. Gaps in the distribution map are primarily due to extensive wetlands or problems of access for collecting litter samples. Quadristruma emmaewas first reported in Florida by Brown in 1 949. There Vol. 1 10, No. 1, January & February, 1999 15 is a specimen from Homestead (Dade County), Florida, dated 25 June 1945, in the Florida State Collection of Arthropods. It is next reported forty years later at a site in south-central Florida (Deyrup and Trager 1986), soon after from several sites in the Florida keys (Deyrup et al. 1 988), then from 1 5 Florida counties (Deyrup et al. 1989), and now from 28 counties. Although this history gives the impression of an exotic species that has had a recent, almost explosive increase through southern and central Florida, this impression is probably wrong. The . . -, . . ff^ <-i *s* i -i /* /s~ /-! r> t f r% *-/~\ r*\ f~\ r\ l\r , I i i ; i i" s^i t r\ f^ c 1 1 f\ i ct\ i f^\ T ^lt^i"C' m IOOT littrtf" trl'it hoc increase in records is probably due to the survey of ants in leaf litter that has been going on over the last 12 years.