Psalidomyrmex, Andre, 1890

Schmidt, C. A. & Shattuck, S. O., 2014, The Higher Classification of the Ant Subfamily Ponerinae (Hymenoptera: Formicidae), with a Review of Ponerine Ecology and Behavior, Zootaxa 3817 (1), pp. 1-242 : 177-179

Psalidomyrmex André

Fig. 40

Psalidomyrmex André, 1890: 313 (as genus). Type-species: Psalidomyrmex foveolatus André, 1890: 314 ; by monotypy.

Psalidomyrmex is a small genus (six described species) restricted to central and western Africa. They are cryptic foragers, and at least one species is a specialist predator of earthworms.

Diagnosis. Psalidomyrmex workers and queens are readily identified by their unique mandibular structure (mandibles falcate to subtriangular, with broadly rounded basal angles and an attenuated apical tooth) and by their projecting labral lobe, both of which are autapomorphic within the Ponerinae . Other diagnostic characters include the hypertrophied frontal lobes, longitudinal groove on the propodeal dorsum, and large lateral metapleural gland orifice. Psalidomyrmex is most similar to the other members of the Plectroctena genus group, including Loboponera and Plectroctena itself. In addition to lacking the two autapomorphies of Psalidomyrmex already mentioned, these genera differ from Psalidomyrmex in having longitudinal dorsal grooves in the meso- and metafemora and distinct propodeal lamellae.

Synoptic description. Worker. Medium to large (TL 9.0–16.0 mm; Bolton, 1975b) ants with the standard characters of Ponerini . Mandibles falcate to subtriangular, with rounded basal angles, a long apical tooth and a basal groove. Labrum projecting anteriorly beyond the anterior clypeal margin as a lobe. Frontal lobes large, expanded laterally and closely approximated. Eyes of moderate size, located anterior to head midline. Metanotal groove vestigial. Propodeum broad dorsally, with a shallow longitudinal groove dorsally. Propodeal spiracles round. Metapleural gland orifice very large, opening laterally. Metatibial spur formula (1p). Petiole nodiform. Anteroventral articulatory surface of petiole long and broad, with a narrow median V-shaped longitudinal groove. Gaster with a strong constriction between A3 and A4. Head and body with moderate sculpturing (variously punctate, foveolate or striate), with very sparse pilosity and no pubescence. Color reddish brown to black.

Queen. Similar to workers but slightly larger, alate and with ocelli.

Male. See description in Bolton (1975b).

Larva. Described for P. procerus by Wheeler & Wheeler (1964).

Geographic distribution. Psalidomyrmex is restricted to central and western Africa, ranging from Sierra Leone to Kenya and as far south as Gabon and the Democratic Republic of Congo ( Bolton, 1975b; Bolton & Brown, 2002).

Ecology and behavior. Very little is known about the ecology and behavior of Psalidomyrmex . They nest in rotting logs, in the soil beneath rotting logs ( Bolton, 1975b), or in deserted termitaries (Déjean et al., 1996, 1997), and workers forage individually in rotting wood or in leaf litter ( Bolton, 1975b). P. procerus is known to be a specialist predator of earthworms ( Lévieux, 1982; Déjean et al., 1992), and though the feeding habits of the other species is unknown, it seems likely that they too may feed on earthworms, given the apparently specialized mandibular structure of the genus.

Phylogenetic and taxonomic considerations. Psalidomyrmex was erected by André (1890) to house the single species P. foveolatus . Bolton (1975b) revised the genus, and Bolton & Brown (2002) gave an updated diagnosis.

André (1890) apparently believed that Psalidomyrmex was closely related to Belonopelta , due to supposed similarities in their mandibular structure. However, P.S. Ward (pers. comm.) found that Belonopelta belongs to the Pachycondyla group while Schmidt (2013) placed Psalidomyrmex in the Plectroctena group. The only real similarity in the mandibles of these genera is the attenuated apical tooth, which occurs in at least two other ponerine genera ( Emeryopone and Thaumatomyrmex ) and this similarity is clearly convergent.

Psalidomyrmex has been grouped with Plectroctena since Emery (1911) included it in his subtribe Plectroctenini , though this was based on weak evidence. Bolton (1974) argued for a close relationship between these genera based on the structure of the mesosoma, petiole and gaster, a similar reduction in palpal segments, and male morphological characteristics. Bolton & Brown (2002) found additional evidence for a close relationship between Psalidomyrmex and Plectroctena in the structure of the anterior petiolar articulatory surface (see also Fisher, 2006). Schmidt's (2013) molecular phylogeny of the Ponerinae confirms this close relationship, with Psalidomyrmex resolved as sister to Loboponera + Plectroctena . Boloponera is also probably in this sister clade.

Figures

FIGURE 40. Worker caste of Psalidomyrmex procerus: lateral and dorsal view of body and full-face view of head (CASENT0003082, April Nobile and www.antweb.org); world distribution of Psalidomyrmex.