Belonopelta Mayr

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 : 138-140

Belonopelta Mayr

Fig. 27

Belonopelta Mayr, 1870: 394 (as genus). Type-species: Belonopelta attenuata Mayr, 1870: 395 ; by monotypy.

Leiopelta Baroni Urbani, 1975: 309 (as genus). Type-species: Belonopelta deletrix Mann, 1922: 9 ; by original designation. Hölldobler & Wilson, 1990: 10 ( Leiopelta as junior synonym of Belonopelta ).

Belonopelta is a small genus (two described species) restricted to the Neotropics. Little is known about their habits, but they are apparently cryptobiotic predators of diplurans and other soft-bodied arthropods.

Diagnosis. Belonopelta workers are easily differentiated from those of most other ponerine genera by their narrow curved mandibles, which have several long teeth. Emeryopone is quite similar to Belonopelta , but they can be separated by their frontal lobes (very small and closely approximated in Belonopelta , medium sized and mildly separated anteriorly in Emeryopone ) and by their body sculpturing and pilosity (pruinose and without upright pilosity in Belonopelta , foveolate with abundant pilosity in Emeryopone ). Thaumatomyrmex also has curved mandibles with an attenuated apical tooth, but its teeth are much longer than in Belonopelta and it has much more widely spaced frontal lobes and larger eyes.

Synoptic description. Worker. Small (TL 4–5 mm) ants with the standard characters of Ponerini . Mandibles narrow and curved, with five or six teeth, the apical tooth greatly attenuated, without a distinct basal margin or basal groove. Anterior clypeal margin triangular, sometimes with a prominent tooth medially. Frontal lobes very small and closely approximated. Eyes very small, located anterior of head midline. Metanotal groove shallow or reduced to a simple suture. Propodeum mildly narrowed dorsally. Propodeal spiracles round. Metatibial spur formula (1p). Petiole nodiform, wider than long. Subpetiolar process sometimes with an anterior fenestra. Gaster with a moderate girdling constriction between pre- and postsclerites of A4. Stridulitrum present on pretergite of A4. Head and body shining to pruinose, with scattered small foveae or punctations, very sparse pilosity and a dense short pubescence. Color reddish-brown to nearly black.

Queen. Described for B. deletrix by Wilson (1955a): similar to worker but slightly larger, alate, with ocelli, larger compound eyes, and the modifications of the thorax typical for alate ponerine queens.

Male. Not described.

Larva. Described for B. deletrix by Wheeler & Wheeler (1964).

Geographic distribution. Belonopelta is restricted to the Neotropics, ranging from southern Mexico to Colombia ( Wilson, 1955a; Baroni Urbani, 1975).

Ecology and behavior. Very little is known about the habits of Belonopelta , as they are rarely collected ( Wheeler, 1935). Their vestigial eyes are suggestive of a cryptobiotic lifestyle, and field observations confirm this, as individual workers are found among leaf litter, under logs or in soil ( Mann, 1922; Brown, 1950; Longino, 2013), and nests are constructed in rotting wood ( Wilson, 1955a). Colonies are small, with roughly 16 or fewer workers and a single dealate queen ( Wilson, 1955a; W. L. Brown, pers. comm. cited in Longino, 2013). Records of Belonopelta food preferences are scant, but Wilson (1955a) observed that B. deletrix workers in captivity readily preyed on diplurans, small geophilid centipedes, and a small cicadellid, but largely ignored large centipedes, termites, beetles (both larvae and adults), moth larvae, isopods, and millipedes. Wilson hypothesized that in nature B. deletrix is largely a specialist predator of diplurans, and observed that the method of prey capture by B. deletrix is typical for ponerines despite their highly specialized mandibular structure. Wilson (1955a) also observed that B. deletrix workers are very timid and readily flee from non-prey arthropods. The degree to which Wilson’s observations of B. deletrix apply also to B. attenuata is uncertain.

Phylogenetic and taxonomic considerations. Belonopelta has had a complicated taxonomic history. Mayr (1870) erected the genus for the single species B. attenuata and noted the general similarity between Belonopelta and Ponera , citing the medial clypeal tooth and highly derived mandibles of B. attenuata as major distinguishing features. Subsequently, the genus Simopelta was at times considered a subgenus ( Mann, 1922) or junior synonym ( Baroni Urbani, 1975) of Belonopelta . Baroni Urbani (1975) revised Belonopelta and made Emeryopone a junior synonym of Belonopelta , at the same time removing B. deletrix to the separate genus Leiopelta . None of Baroni Urbani’s (1975) genus-level taxonomic changes withstood scrutiny by subsequent authors, as Hölldobler & Wilson (1990) synonymized Leiopelta under Belonopelta and moved Simopelta back to full genus status, and Bolton (1994) moved Emeryopone back to full genus status. See the discussion under Simopelta for more on the phylogenetic position of that genus.

Recently, P. S. Ward (pers. comm.) examined a number of primarily African ponerines using molecular data and found Belonopelta to be closely related to Thaumatomyrmex . Combined with Schmidt’s (2013) demonstration that Thaumatomyrmex is close to Simopelta , it appears that these three genera form a clade or basal grade. As these three genera belong to the Pachycondyla group and Emeryopone is in the Ponera group, Baroni Urbani’s (1975) belief that B. attenuata and Emeryopone are congeneric (with B. deletrix excluded) is not supported. We are here retaining Belonopelta as a separate genus from Emeryopone as the available data suggest that they are unrelated.

Figures

FIGURE 27. Worker caste of Belonopelta deletrix: lateral and dorsal view of body and full-face view of head (CASENT0260514, Shannon Hartman and www.antweb.org); world distribution of Belonopelta.