Probolomyrmex

Yoshimura, M. & Fisher, B. L., 2009, A revision of male ants of the Malagasy region (Hymenoptera: Formicidae): Key to genera of the subfamily Proceratiinae., Zootaxa 2216, pp. 1-21 : 12-13

Probolomyrmex Mayr, 1901

(Figs 3, 9, 14, 17, 20, 28, 32)

With characters of Proceratiinae . Mandible smaller than in conspecific worker, but also triangular to subtriangular. Frontoclypeal region projecting dorsally. Frontal carinae merged into single median carina (Fig. 14). Antennal socket opening posteriorly. Antenna with 13 segments. Labrum bilobed apically (Fig. 28). Second segment of maxillary palp hammer-shaped (Fig. 32). Pro-, meso-, and metatibia with a single spur. Pygostyles absent.

On forewing, costa excluding basal portion, radius, radial sector between Rs+M and 2r-rs, and 2rs-m and m-cu crossveins absent, the stigmal vein (sensu Bolton 2003: 49) formed by combination of 2r-rs and radial sector apical to the 2r-rs (Fig. 3). On hindwing, M+Cu present or vestigial (unclear only in P. mgm01), free section of the radius and cubitus, and cu-a crossvein absent (Fig. 9). Radial sector apical to R+Rs present or absent.

Remarks. The genus Probolomyrmex in the Malagasy region is distinguished easily from the three other Malagasy proceratine genera by the forewing stigmal vein. See also discussions under Discothyrea and Proceratium .

Brown (1958) and Baroni Urbani and De Andrade (2003) have suggested that the hammer-shaped second segment of the maxillary palp is a synapomorphy of the genus Proceratium (Fig. 33). However, the hammer-shaped maxillary palp was also observed in all specimens of Probolomyrmex examined in the present study (Fig. 32).

All males of Probolomyrmex found in the Malagasy region belong to the greavesi group as defined by Eguchi et al. (2006: discussion). Of the diagnostic characters proposed by Eguchi et al. (2006), short frontoclypeal region, shorter first flagellar segment (third antennal segment) compared with the pedicel (second antennal segment) (Fig. 14), short petiolar node with steep anterior slope in lateral view (Fig. 20), and absence of Rs+M and media apical to Rs+M in forewing were observed (Fig. 3). These characters are useful in distinguishing the greavesi group from the longinodus group. However, cu-a in the forewing was present in all male specimens, and absence of media basal to Rs+M was unclear. Shape of the ninth abdominal sternum and the retractility of genitalia were unconfirmed.