Polyrhachis dohrni species-group

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The Polyrhachis gravis species-group is comprised of species in the subgenus Aulacomyrma.

Species

Identification

Diagnosis

This group is characterized by the following: mesosoma distinctly and fully laterally marginate with margins interrupted only at sutures. Pronotal humeri armed with broad-based teeth, short spines or acute angles which are laterally continuous with the pronotal margins. Propodeal dorsum terminating in dentiform angles or tubercles, but also in distinct, posteriorly directed tooth-like prominences as in roberti and lumi, or in laterally directed blunt teeth as in wardi. In one species, wilsoni, the lateral margins are greatly extended and terminate in long, outwardly curved, acute spines. Posterior margination of propodeum varying from complete transverse ridge separating dorsum from declivity as in exarata and parva, where ridge is straight, and wilsoni, where it is deeply curved inwards, to a situation where posterior margin is lacking and both surfaces are confluent, as in dohrni or pallipes. Petiole scale-like with anterior and posterior faces convex and dorsal margin acute, with rather distinct lateral spines or teeth. Species related to dohrni have dorsal petiolar margin entire, or at most weakly jagged, as in lumi; in roberti and simulans dorsal petiolar margin medially emarginate with short teeth or denticles flanking emargination. Anterior face of first gastral segment in all but one species (roberti) distinctly concave, accommodating posterior face of petiole; anterodorsal margin of concavity acute and weakly elevated, as in pallipes and planata, or blunt and not at all raised above dorsal surface of segment, as in abdita and simulans. Sculpture of head and mesosomal dorsum consisting of mostly longitudinal striation, that in most species tends to be anteriorly convergent on pronotum. In two species, roberti and simulans, longitudinal sculpture is virtually absent from clypeus that is virtually smooth, only very finely reticulate-punctate.

The nomenclature section of the Aulacomyrma subgenus page also includes information about distinctions between this species-group and the Polyrhachis porcata species-group.

Related Pages

References