Strumigenys metrix

Identification
Bolton (2000) - A member of the Strumigenys schulzi-group. Closely related to Strumigenys orchibia and Strumigenys schulzi and sharing the same dental pattern, but much darker in colour than either of them. The former is rich medium brown throughout and the latter yellow to light yellowish brown, whilst metrix is dark brown with a blackish brown gaster. In orchibia, and usually also in schulzi, the katepisternum is entirely reticulate-punctate, but in metrix it is almost entirely smooth. Standing pilosity on the head and alitrunk is strongly differentiated from ground-pilosity in both schulzi and orchibia but the difference is not nearly so marked in metrix where the hairs are very stubby and scarcely longer than the ground-pilosity.

Distribution based on Regional Taxon Lists
Neotropical Region: Paraguay.

Nomenclature

 *  metrix. Pyramica metrix Bolton, 2000: 222, fig. 153 (w.) PARAGUAY. Combination in Strumigenys: Baroni Urbani & De Andrade, 2007: 124

Worker
Holotype. TL 2.1, HL 0.60, HW 0.42, CI 70, ML 0.09, MI 15, SL 0.28, SI 67, PW 0.30, AL 0.60. Anterior clypeal margin transverse; lateral margins distinctly divergent posteriorly, the degree of divergence greater than that of the outer margins of the mandibles. Dentition as described above. Scape narrow basally, its anterior margin abruptly broadened at the subbasal angle and broadest just distal of this; scape then gradually tapering toward the apex. Eye large, with 6 ommatidia in the longest row and with more than 20 ommatidia in total. Ground-pilosity of head of anteriorly curved dense small spatulate hairs. Behind highest point of vertex with a transverse row of 6 hairs that are slightly longer, stouter and more erect than the ground-pilosity, but are not strikingly differentiated. Dorsolateral margin of head with anteriorly curved small spatulate hairs breaking the outline in full-face view, and with a somewhat larger more prominent apicoscrobal hair. Pronotal humeral hair short but longer, straighter and more clavate apically than the distinctive ground-pilosity of the dorsum. Dorsolateral margins of mesonotum with 3 pairs of short hairs projecting above the level of the ground-pilosity. Dorsum and sides of alitrunk uniformly densely reticulate-punctate except for an extensive patch on the katepisternum that is smooth and shining. Petiole ventrally with a cuticular carina but without trace of spongiform tissue. Dorsal surfaces of waist segments and first gastral tergite with numerous stubbly hairs that are suberect to erect and weakly clavate apically. Petiole node broader than long in dorsal view and without laterally projecting spongiform lobes. Petiole and disc of postpetiole densely reticulate-punctate. First gastral tergite smooth behind the basigastral costulae. Very darkly coloured species; head and alitrunk dark brown, gaster blackish brown.

Type Material
Holotype worker, Paraguay: Canendiyu, Ype Jhu, 28.x. 1979 (F. Baud).