This is a locally abundant species that prefers pure sand, where it often builds crater mounds or nests at the base of grass clumps. According to Naves (1985), colonies are large and live primarily as scavengers, although they also occasionally collect seeds. Workers have been observed foraging as much as 8 meters or more from the nests. Minors forage singly at night, with majors often emerging from the nest to help carry back food. Nest-founding queens build vertical passageways to a claustral chamber 20–30 cm below the surface, and use the excavated soil of the chamber to plug the passageway. Naves observed rapid growth in incipient colonies: the first minors emerge in 30 days, the first majors in 50 days, with colonies growing to several hundred workers in 8 months. In New York winged queens are present in nests during July, and in Florida as early as May (Stefan Cover, unpublished records). Cover (personal communication) has also noted that morrisi “shows a fascinating variation in life history over its large geographic range. Populations in the northeast (Long Island and New Jersey pine barrens) have pleometrotic colony founding, and exhibit primary polygyny—one of the very few documented cases in the ants. Colonies are almost always monodomous. In the southeastern United States, morrisi is haplometrotic and monogynous but colonies are often polydomous.” (Wilson 2003)
|At a Glance||• Polygynous|
- 1 Identification
- 2 Distribution
- 3 Biology
- 4 Castes
- 5 Nomenclature
- 6 References
See the description in the nomenclature section.
Keys including this Species
Long Island, New York south to South Florida, and west to Illinois, Missouri, Oklahoma, and Texas. (Wilson 2003)
Distribution based on Regional Taxon Lists
Distribution based on AntMaps
Distribution based on AntWeb specimens
Check data from AntWeb
Naves (1985) - P. morrisi is a common species in Florida It always nests in the ground and the colonies are quite large. It is a monogynous species and is primarily a scavenger.
Several nest founding females displayed singular habits in the laboratory which may not have been noted previously in this genus. In constructing the claustral chamber each female used the soil dug from the bottom of the vertical passageway to form a continuous plug of the passageway above her rather than bringing the soil particles to the surface. The claustral chamber at the 20 to 30 cm level below ground thus is entirely sealed from the surface by a long plug I interpret this habit as a defense mechanism against various predators during the claustral period The first workers are reared in about 30 days and the first majors in about 50 days.
The colony increases in size rapidly. In 8 months it can have several hundred workers and majors. The workers forage alone, although the majors can help to bring food back to the colony once food is located Workers can forage over 8 m from the nesting site. The species is mainly a scavenger but will also gather seeds.
The following information is derived from Barry Bolton's New General Catalogue, a catalogue of the world's ants.
- morrisii. Pheidole morrisii Forel, 1886b: xlvi (s.w.) U.S.A. Forel, 1901e: 350 (q.m.); Wheeler, G.C. & Wheeler, J. 1960b: 12 (l.). Senior synonym of vanceae: Creighton, 1950a: 183; of impexa: Wilson, 2003: 325. See also: Feener, 1987: 569.
- vanceae. Pheidole morrisii var. vanceae Forel, 1901e: 351 (s.w.q.m.) U.S.A. Junior synonym of morrisii: Creighton, 1950a: 183.
- impexa. Pheidole morrisi var. impexa Wheeler, W.M. 1908e: 461, pl. 27, fig. 31 U.S.A. Subspecies of morrisii: Creighton, 1950a: 184. Junior synonym of morrisii: Wilson, 2003: 325.
Unless otherwise noted the text for the remainder of this section is reported from the publication that includes the original description.
From Wilson (2003): A member of the fallax group easily distinguished by the following traits.
Major: yellow; antennal scape approaches occipital corner within 2! its own width; propodeal spines reduced to denticles; rugoreticulum lacking on head; pilosity dense and very long, many hairs longer than Eye Length; postpetiole from above elliptical, with subangulate lateral borders.
Minor: yellow; propodeal spines reduced to right or obtuse angles; occiput slightly narrowed, with thin nuchal crest. The types of impexa differ from typical eastern morrisi in having two-layered gastral pilosity, flattened scape at the bend, and a more narrowly tapered petiolar node in the major. I have treated the form as a western geographic variant, i.e., from Oklahoma and Texas, but it may prove to be a distinct species.
MEASUREMENTS (mm) Major (Selden, New York): HW 1.26, HL 1.26, SL 0.88, EL 0.24, PW 0.62. Minor (Selden, New York): HW 0.60, HL 0.82, SL 0.90, EL 0.16, PW 0.40.
COLOR Major: concolorous yellow.
Minor: yellow, with head and mesosoma a slightly darker shade than rest of body and appendages.
Figure. Upper: major. Lower: minor. NEW YORK: Selden, Suffolk Co. Scale bars = 1 mm.
Vineland, New Jersey. Musee d'Histoire Naturelle Genève - as reported in Wilson (2003)
Eponymous. (Wilson 2003)
- Creighton, W. S. 1950a. The ants of North America. Bull. Mus. Comp. Zool. 104: 1-585 (page 183, senior synonym of vancecae)
- Feener, D. H., Jr. 1987. Response of Pheidole morrisi to two species of enemy ants, and a general model of defense behavior in Pheidole. J. Kans. Entomol. Soc. 60: 569-575 (page 569, see also)
- Forel, A. 1886b. Espèces nouvelles de fourmis américaines. Ann. Soc. Entomol. Belg. 30:xxxviii-xlix. (page xlvi, soldier, worker described)
- Forel, A. 1901j. Variétés myrmécologiques. Ann. Soc. Entomol. Belg. 45: 334-382 (page 350, queen, male described)
- Naves, M. A. 1985. A monograph of the genus Pheidole in Florida, USA (Hymenoptera: Formicidae). Insecta Mundi 1: 53–90.
- Tschinkel, W.R. 2015. The architecture of subterranean ant nests: beauty and mystery underfoot. Journal of Bioeconomics 17:271–291 (DOI 10.1007/s10818-015-9203-6).
- Wheeler, G. C.; Wheeler, J. 1960b. Supplementary studies on the larvae of the Myrmicinae (Hymenoptera: Formicidae). Proc. Entomol. Soc. Wash. 62: 1-32 (page 12, larva described)
- Wilson, E. O. 2003. Pheidole in the New World: A dominant, hyperdiverse ant genus. Harvard University Press, Cambridge, MA. (page 325, fig. major, minor described, Senior synonym of impexa)