Monomorium pergandei

DuBois (1986) - This species was discovered in a nest of Monomorium minimum. It is presumed to be a social parasite in view of the morphological features it shares with other species of inquilinous Monomorium (see section on inquilinism). This species has only been collected once (almost 100 years ago), and is probably now extinct. One detail recorded, and perpetuated through the literature (i.e., Wheeler, 1910: 498; Creighton, 1950: 239-241), was that when the colony containing M. pergandei was taken to the laboratory, Pergande noted that reproductive of M. minimum were also present in the nest. As he watched, the M. pergandei females attacked and killed some of the M. minimum males. This seems rather unusual behavior if the reproductives of the two species coexisted previously in the same nest. However, Wheeler (1910: 498) points out that Pergande may have collected two colonies in close proximity to each other, with one colony containing M. pergandei reproductives and M. minimum workers, while the other colongy contained M. minimum reproductives. Wheeler then supposed these two colonies were combined in the laboratory and the observed behavior ensued.

Identification
DuBois (1986) - Female: Winged; scutum and scutellum convex; metanotum (in lateral view) projecting above level of propodeum and scutellum; propodeum angular; clypeus emarginate, teeth blunt and reduced; anterior edge of scutum projecting over pronotum.

Monomorium pergandei is easily recognized by the small size of the female (compared to the size of the host), the smooth and shining integument, the abundance of erect to suberect setae over most of the body, the spine projecting where the postpetiolar process is usually located, and the large depression on the dorsum of the first gastral tergite. Females of this species are most similar to Monomorium inquilinum. However, these two species can easily be separated, since the metanotum only projects to the level of the propodeum and scutellum and there are only two mandibular teeth in M. inquilinum. The petiolar node is flat and the anterior edge of the scutum does not project over the pronotum in M. inquilinum. These same characters distinguish females of M. talbotae, which also lack a dorsal impression on the first gastral tergite.

Distribution
Washington D.C., USA.

Distribution based on Regional Taxon Lists
Nearctic Region: United States.

Nomenclature

 *  pergandei. Epoecus pergandei Emery, 1893a: cclxxvi (q.m.) U.S.A. [Also described as new by Emery, 1895c: 273, pl. 8, figs. 11, 12.] Combination in Monomorium: Ettershank, 1966: 91. See also: DuBois, 1986: 113; Bolton, 1987: 299.

Queen
DuBois (1986) - As described for Monomorium talbotae except as follows. Head. (representing type locality; N= 2) HL 0.44-0.48 (0.46), HW 0.39-0.40 (0.40), SL 0.40-0.42 (0.41), IOD 0.09-0.10 (0.10), OD 0.04-0.05 (0.04), EL 0.09-0.10 (0.10), MOD 0.08-0.09 (0.08). Structure—CI 83-89 (86), SIL 88-90 (89), SIW 103-105 (104). Scape surpassing occiput by an amount slightly greater than length of pedicel. Mandible with three teeth. Clypeal teeth blunt, short. Alitrunk: PW 0.30-0.33 (0.32), PL 0.22-0.28 (0.25), WL 0.72-0.81 (0.76). Structure—Mesonotum with small notal furrow. Scutum and scutellum not depressed. Anterior edge of scutum projecting over pronotum. Mesopleural suture deflected dorsally at posterior end and ventrally at anterior end; small pit at each end. Metanotum (in lateral view) projecting above level of propodeum and scutellum. Propodeum angular. PI 30-35 (32). Petiole: Dorsum of node flat, smooth and shining with small piliferous punctures. Remaining surfaces covered with moderately dense, non-piliferous punctures. Postpetiole. Dorsum of node weakly emarginate. Gaster. As in M. minimum except as follows: first gastral tergite with basal depression. Color. Head brown to dark brown except as follows: mandible and antenna yellow brown to yellow. Alitrunk brown, legs yellow brown to yellow. Petiole, postpetiole, and gaster brown. All setae white.

Male
DuBois (1986) - Although males and females of M. pergandei were collected from the same nest, no male specimens could be located for this study. One badly damaged specimen (gaster missing) is labelled as a male in the NMNH collection. The head and alitrunk resemble those of a female. This may actually be a male if the sexes in M. pergandei are as similar as they are in M. talbotae.

Type Material
DuBois (1986) - Type series consisting of lectotype and 6 paralectotype queens, designated by DuBois (1981a): District of Columbia: Washington, 12 July (year unknown but before 1892), T. Pergande. Lectotype and 4 paralectotypes in, remaining paralectotypes in. All specimens bear red, handwritten labels: Monomorium pergandei Lectotype (or Paralectotype) M. DuBois 1980.