Monomorium inquilinum

This species was discovered in a nest of Monomorium cyaneum beneath a stone. It is presumed to be a social parasite because of the morphological features shared with other inquilinous Monomorium. Monomorium inquilinum is known only from the type locality.

Identification
DuBois (1986) - Female: Winged; petiole emarginate; scutum and scutellum not depressed; metanotum (in lateral view) projecting to level of propodeum and scutellum; propodeum angular; clypeus emarginate, lacking teeth; anterior edge of pronotum rounded.

The Monomorium inquilinum female is most similar to Monomorium pergandei and Monomorium talbotae females. It can be easily be separated from these species since the petiole is emarginate only in M. inquilinum. Furthermore, the metanotum does not reach the level of propodeum and scutellum in M. talbotae, and the mesonotum possesses a furrow in M. pergandei.

Distribution based on Regional Taxon Lists
Neotropical Region: Mexico.

Castes
Known only from the queen caste, this species is presumed to have no worker caste.

Nomenclature

 *  inquilinum. Monomorium inquilinum DuBois, 1981: 34, fig. 2 (q.) MEXICO. See also: DuBois, 1986: 116.

Queen
As described for Monomorium talbotae except as follows. Head: {representing holotype only} HL 0.45, HW 0.39, SL 0.40, IOD 0.10, OD 0.04, EL 0.10, MOD 0.08. Structure—CI 89, SIL 89, SIW 100. Scape surpassing occiput by amount slightly greater than length of pedicel. Labial palp 2-segmented. Clypeal teeth absent (clypeus retaining emargination where space between teeth should occur). Alitrunk: Measurements PW 0.30, PL 0.15, WL 0.66. Structure—Mesopleural suture straight. Metanotum (in lateral view) projecting to level of propodeum and scutellum. Propodeum angular, basal face length half length of declivitous face. PI 22. Wings absent (presence of basal sclerites indicate holotype once possessed wings). Pilosity—As in M. cyaneum. Sculpture—As in M. talbotae. Petiole. Dorsum of node emarginate. Entire surface (except dorsum of petiolar node) covered with small, dense, nonpiliferous punctures (causing a granular appearance); dorsum of node smooth and shining with small piliferous punctures. Postpetiole. Dorsum of node emarginate. Gaster: As in M. pergandei. Color: Head dark brown, antenna yellow. Alitrunk dark brown, legs brown (tibiae and tarsi yellow). Petiole, postpetiole, and gaster dark brown. All setae white.

Type Material
DuBois (1986) - Known only from the holotype (DuBois, 1981a): Estado de Mexico: Highway 57 (between Mexico City and Queretaro), km 127 (measured from Mexico City), high desert, Cornell University Mexico Field Party, 9 August 1965 (1 female, ).