Vol. 1, no. 2, ~1areh 1985 INSECTA I1UNDI 53 -----------I.A..- ~S~------ PHEIDOLE~A By Marcia A. Naves 2 INTRODUCTION The genus Pheidole is one of the more illll'ortant ant With the help ofkeys and seanning eleetron mierographs genera in the world Approximately 1000 speeies are now it is now possible to identify, with relative ease, both the majors known. Over 400 of these are found in the Neotropical region and the workers of the species of this genus known to occur in (Kempf, 1972), and about 75 taxa are known from North Florida America north ofMexico. Pheidole spp. are abundant in many areas, and live in varying habitats rangingfrom the humidtropies REVIEW OF LITERATURE. Four of twelve spedes to deserts. They are able to survive in some areas by their habits reported from Florida have that state as the type locality ofthe ofeolieeting and storing seeds as food resourees. They are also speGies: P. dentata Mayr(UHl6), P. floridana Emery(l&95), R scavengers of dead insects and other animals, and can be metallescens Emery (1895), and P. sitarches litorallis Cole predacious. Some speGies tends aphids and other homopterans, (1952). but this food source, so important to many ant species, is Smith(1930) reportedP. morrisi; Wheeler(1932) reported probably of relatively minor importanGe to most speGies of R anastasii; Smith (1933) reported R megacephalii; Smith Pheidole. (1944) reported P. dentigula; Smith(1951) reported P. flavens Pheidole apparently is a geilUS ofrather recentevolutionary sculj)tlOr (misidentification); Van Pelt (1956) reported R development No fossil Pheidole are known previous to the pili/era; Smith (1958) reportedP. bicarinata vinelandica, and Miocene (Brown, 1973). No Pheidole occur in Baltic amber WOjcik etat. (1975) reported P. moerens. Ad<iltional iriformation (lower Oligocene) although these ambers contain large numbers is discussed under each species by the respective authors of speCimens of other ant genera which have perSisted almost CreigJlton (1950) was the hrst to try to give an extenSive unchanged since that epoch (species of Formica, Myrmica, key to the North America Pheidote; 63 species were listed, and lrzdomyrmex. Camponotus, and others). It has been said that he used morphological characters pertinent to both majors and Pheidole has undergone a world wide dispersal since this time workers Creighton's statements about the North American and has undergone a large prohferation of taxa as well as Pheldote are as follows: adaptation to many ecological nitches (Brown, 1973) A study of the Pheidole of any area is one of the Most of our species of Pheidole possess a dimorphic prerequisites to understandmg the fOommd mteracfJons of that worker easte ·I'.'ith ml\ior and minor workers not eonneeted area, and this in tum could be important in the development of by intennediates. In a few species, however, the worker orpesc .l; • vas II arzzomca, e c.. os 0 e species and most important animals within their size range. garner seeds and it is believed that the large- headed major One species, Pheldole megacephata, has become a workers fooetion as seed-huskers. The enlarged head of tropicopolitan tramp species and is a serious pest in various the major is mainly tilled with mandibular muscles This areas (Wheeler, 1910; Plucker and Beardsley, 1970; and enables the Jaws to exert much pressure, which should be Lieburg, 1975). Some species sting severely and are comparable useful in cracking off the husks ofseeds. It may be added with the tire ants in aggreSSiveness (Buren, personal communI­ that sOIlIetillIes the head of the IlIajol is so latge in cation). Mostofthe species, however, appear innocuous and are proportion to its body that if the insect is turned over on usually unnoticed by man Their importance in the ecosystem the back of its head it cannot regain a normal posture appears largely unappreciated without help from other workers. Despite their preference for a gramlnlvourous diet many species of Pheldole will Due to its size and distribution, Pheidole is a very difficult accept other food as well They seem less attracted to genus andhas been a challenge to myrmecologists taxonomically honey dew than do mllll) ants ImtwiU often feed .0raeiOllsry as well as biologically. on animal tissue when the opportunity offers. The majority Until lecently only eleven species were known from of our species fuon small colonies In many cases there Florida, which suggests that, despite its subtropical warmth, are only about two or three hundred individuals in a fully Flotida was deficient in Pheidule when compated to Texas(36 developed nest Even ill die case of the species which species) and Arizona (26 species). The Florida Pheidole fauna produce comparatively large nests (P. morris~ P. hyalt~ has long been known to be mOle extensive than that of IIDI thel n p. deserwru m, etG.) a colony of JIl()re than two or three states such as Iowa and New Jerse 3 s ecies eac Bure thousand individuals would be exceptionally large. By far 1944, Cleighton; 1950). e maJon y 0 our species nes In SOl e nes may e built under a stone or in open soil without a covering lylorida Agr. Exp. 8ta. , Journal 8eries No 6257 object In the latter ease there is often a mound or craters 2EMBRAPA - ED. VENANCIO 2.000-8/916-70.333 BRAZ1LIA-DF-BRA81L 54 INSECTA MUNDI Vol. 1, no. 1, January 1985 of excavated soil surrounding the nest entrance. The chamber with an interconnecting exit hole. This construction easteIII species dentuta will nest ill Ioltelliogs as well as allowed colonies to be maintained in the laboratory for long soil but such flexibility in nesting habit is exceptional periods with only infrequent attention. The dry feeding area (p 1(2) separated from the nest chamber inhibited the growth ofmolds. LaS;r numbers ofcolonies were thus kept in a small laboratory Gregg (1958), published peanuts, and honey. Whenevel possible field observations wele made COIF ceming the ecology and biology of each species. Types in the Museum ofCwnpalative Zoology, Halvald reported or 0 enca no 0 eXlCo. 0JCI et a . University, Cambridge, Massachussetts, and the National (1975) reported that this species was also present in Florida Museum of NatUIal HistOIy in'Nashington; D.C., ofNealctic and Neotropical Pheidole were studied MAIERIAI.S ANn MEIHOI)S Ihree species of All specimens wele point mounted and studied by using a Pheidole(P. dentigula, P.fallaxobscurithorax, andP. greggin stereo microscope with magnification up to l60X The pictures sp) included in this research were received frOm other collectors were taken using the scanning electron microscope ofthe Insects AIl other specimens were collected by the author during several Attractants Laboratory, Agricultural Research Service, U. S. D.A, trips in the state or while at Tall Timbers ResearCh Station in Gainesville, Florida Leon Co., Florida, during the summers of 1974 and 1975. Several measurements were made for the newly described Colomes of Pheldote spp. were located In several ways: species: a Examining cavities under the barkoftrees orexamining a Body lengC-.: the sum of the head length, thoracic grass behind the leaf bases of palms. length, pedicel and gastric lengths. b. Searching for nest craters, mounds, or any other b. Head lengt.l...: lengths of the head in full faee 'lie'll modification on the soil surface likely to have been produced by (mandibles excluded). ants. c. Headwidth: greatestwidth ofthe head in full face '1iew. c. Searching for foraging majors or workers andfollowing d Thoracic length: greatest length of thorax in lateral them to the nest location. view. d Baiting with honey or dead arthropods and following e. Scape length: middle of antennal socket to the scape nails of wmkels and maims to the nest location tip. e. Overturning stones, boards, or pieces of wood f. Scape index: found by computing the fonnula: The two most successful methods wele examiningcavities Scape length X 100 under the bark of pine trees and looking for craters on the soil head length SUIface. The fOllowing abbreviations "'ere used throughout this Colonies were collected by aspirating the ants once the work: chambeIS wele located Nests in the soil wele excavated by MCZC - Museum of Comparative Zoology, Harvard removal of large blocks of soi~ breaking it carefully and University, Cambridge, Massachussetts aspirating the ants found The depth explored was variable, USNM - Umted States NatIOnal Museum, WashIngton, ranging from 30 to 50 cm for P. metallescens to over1.5 m for P. DC lamia AMNH - Amencan Museum of Natural HistOry, New The ants were placed in snap-cap vials with 70% alcohol York, NY for preservation or kept ali'le in snap- eap vials with a pieee of moistened cotton to ensure adequate survhat The snap-eap KEY TO SPECIES OF PHEIDOLE OF FLORIDA vials were placed in a styrofoam box to protect them against (MAJORS ONLY) excessi'le changes in temperature during transport back to the laboratory. 1a Head cylindncal In cross section and obliquely truncate The colonies were kept in chambers made from petri anteriorly, the truncation involving the dypeus, frontal dishes modified to assure proper high moisture levels and ease of area, antenor portIOns of genae, and mandibles. feeding and observation without disturbing the colony. (fig 1) lamia Wheeler Plastic petri dishes 9 cms in diameterwere used A 0.5 cm b. Head not cylindrical in cross section and not truncate hole was melted by a solderingiron towardthe side orthe bottom a~fu~ 7 ofone dish. A piece ofartificial cotton matting was pushed half 2a Antennal scape strongly bent, flattened and smooth at the way through the hole and was coated inside "'ith a mixture of base, tbe base nearly as oras broad as tbe distal portions of plaster of paris (98%) and commercial cement (2%).