Pseudomyrmex oculatus

A widespread and common species that nests in dead twigs or branches of trees.

Identification
Ward (1989) - This common, widely distributed species shows considerable geographical variation (particularly in size, sculpture, color, and head shape), but it is at once recognizable by the distinctive shape of the petiolar node. The sudden, subangulate juncture of the dorsal and posterior faces of the node is seen in no other related species. Also characteristic of P. oculatus are the elongate eyes (see REL and REL2 values), relatively broad head, the (typically) punctate-opaque sculpture of the head, and the shape of the postpetiole in lateral view (summit of postpetiolar node displaced posteriorly relative to other species in the P. oculatus group, except P. schuppi).

Distribution
Ward (1989) reported specimens from Belize, Bolivia, Brazil, Colombia, Costa Rica, Ecuador, French Guiana, Guatemala, Guyana, Honduras, Mexica, Nicaragua, Panama, Peru, Trinidad and Venezuela.

Distribution based on Regional Taxon Lists
Neotropical Region: Belize, Bolivia, Brazil, Colombia, Costa Rica, Ecuador, French Guiana, Guatemala, Guyana, Honduras, Mexico, Nicaragua, Panama, Peru, Suriname, Trinidad and Tobago, Venezuela.

Biology
Ward (1989) - P. oculatus is typically found nesting in dead twigs or branches, in rain forest or at the edge of rain forest, less frequently in open or drier habitats. Specific nest-site records include dead twigs of Ficus, Hampea, Inga, Vochysia, and various unidentified lianas; I found one colony in the dead leaf sheath of a Seheelea palm.

De Oliveira et al. (2015), studying ant occupancy of Cecropia trees in southwest Bahia, Brazil, found a colony of  nesting in a Cecropia pachystachya tree.

Nomenclature

 * advena. Pseudomyrma advena Smith, F. 1855c: 157 (q.) BRAZIL. Junior synonym of oculatus: Forel, 1911e: 277.
 *  oculatus. Pseudomyrma oculata Smith, F. 1855c: 159, pl. 13 (w.q.) BRAZIL. Combination in Pseudomyrmex: Kempf, 1961a: 375. Senior synonym of advena: Forel, 1911e: 277; of dolichopsis, implicata: Kempf, 1961a: 375; of altinoda, tuberculata, wessoni: Ward, 1989: 422.
 * dolichopsis. Pseudomyrma dolichopsis Forel, 1899c: 87 (w.) COSTA RICA. Junior synonym of oculatus: Kempf, 1961a: 375.
 * implicata. Pseudomyrma dolichopsis var. implicata Forel, 1911e: 277 (w.) BRAZIL. Junior synonym of oculatus: Kempf, 1961a: 375.
 * altinoda. Pseudomyrma sericea var. altinoda Mann, 1916: 427 (w.) BRAZIL. Combination in Pseudomyrmex: Kempf, 1972a: 223. Junior synonym of oculatus: Ward, 1989: 422.
 * tuberculata. Pseudomyrma wessoni var. tuberculata Enzmann, E.V. 1944: 98, pl. 4, fig. 25 (w.) PERU. Combination in Pseudomyrmex: Kempf, 1972a: 226. Junior synonym of oculatus: Ward, 1989: 422.
 * wessoni. Pseudomyrma wessoni Enzmann, E.V. 1944: 97, pl. 3, fig. 10 (w.) PERU. Combination in Pseudomyrmex: Kempf, 1972a: 226. Junior synonym of oculatus: Ward, 1989: 422.

Worker
Ward (1989) - measurements (n=24). HL 0.94-1.09, HW 0.73-0.91, MFC 0.017-0.031, CI 0.77-0.87, OI 0.57-0.61, REL 0.55-0.62, REL2 0.67-0.78, OOI (-0.20)-0.37, VI 0.72-0.81, FCI 0.021-0.037, SI 0.46-0.50, SI2 0.62-0.72, FI 0.40-0.44, PDI 0.97-1.40, MPI 0.032-D.056, NI 0.72-0.81, PLI 0.86-1.01, PWI 0.66-0.82, PPWI 1.35-1.61.

diagnosis. Medium to large species, for the oculatus group (HW 0.73-0.93), with broad head (CI 0.77-0.87) and with large, elongate eyes which tend to protrude conspicuously from the sides of the head and which typically (but not always) reach the level of the median ocellus, when head is held in full-face view; occipital margin flat to moderately concave; funicular segments II and III about as long as broad, or nearly so. Fore femur relatively slender (FI 0.40-0.44); metanotal groove moderately impressed; basal face of propodeum flat to weakly convex (lateral view), conspicuously elevated anteriorly above level of mesonotum; basal face of propodeum usually exceeding length of the declivitous face and rounding into the latter, which is laterally submarginate. Petiolar node high and subangulate, with distinctive lateral profile: anterior face smoothly continuous with the flattened, posteriorly uplifted dorsal face which itself rounds sharply into the vertical posterior face; anteroventral petiolar process conspicuous, variable in shape (from bluntly rounded to slightly recurved and hook-like); postpetiole broader than long, in lateral view appearing rather high, with the convex, gradually ascending anterorlorsal face rounding into a more steeply descending posterior face.

Head densely punctate and typically opaque; becoming sublucid on upper third of head in some individuals, because of shiny interspaces between some of the punctures. Mesosoma punctate to coriarious-imbricate and predominately opaque; petiole, postpetiole, and gaster subopaque, covered with numerous fine piligerous punctures. Erect pilosity and appressed pubescence common on most of body, including mesosoma dorsum. Medium to dark brown, the antennae, tibiae, and tarsi variably lighter, often contrastingly so; pronotum and parts of head sometimes lighter in color than gaster; mandibles pale luteous.

Type Material
Ward (1989):

Two syntype worker " Santarem, Brazil (Bates) [Examined]. One syntype worker here designated LECTOTYPE.

Pseudomyrma dolichopsis Forel, 1899:87. Syntype workers. Suerre. Jimenez, Costa Rica (Alfaro) [Examined].

Pseudomyrma dolichopsis var. implicata Forel, 1911:277. Two syntype workers, Amazonas (Bates) (MHNG) [Examined]. One syntype worker here designated LECTOTYPE.

Pseudomyrma sericea var. altinoda Mann, 1916:427. Syntype workers Porto Velho, Rio Madeira, Brazil (Manr. & Baker) [Examined].

Pseudomyrma wessoni Enzmann, 1945:97. Syntype queen, Peru, (MCZC) [Examined].

Pseudomyrma wessoni var. tuberculata Enzmann, 1945:98. Holotype worker, Peru [Not examined].

Lectotypes of both P. oculatus and P. implicatus are designated because the apparent type series of these taxa contain more than one species. In the BMNH, under P. oculatus, I found three species: (1) two syntype workers of what is here interpreted to be P. oculatus, from Santarem, Brazil; (2) an alate queen of Pseudomyrmex peperi (Forel), a Central American acacia-ant labelled (obviously erroneously) "Santarem"; and (3) four workers of Pseudomyrmex filiformis, two of which (from Villanova, Brazil) were labelled as types of P. oculatus. The type series of P. implicatus in MHNG contains two species: (1) two workers of P. oculatus; and (2) one worker of Pseudomyrmex curacaensis. For nomenclatural stability I have chosen as lectotypes of P. oculatus and P. implicatus those workers which correspond to the species described (at least as a queen) and illustrated (as a worker, under the name P. advena) by F. Smith (1855). The choice of lectotypes is also consistent with Kempf's (1961) concept of P. oculatus, which was based on an examination of material in the Hope Collection, Oxford (OXUM) which Kempf considered to represent part of the type series of P. oculatus.

The syntype queen of P. wessoni (Enzmann) is clearly conspecific with P. oculatus. Unfortunately, the type of P. wessoni tuberculatus (Enzmann) cannot be located, and second-guessing the identity of Enzmann's creations is an unsatisfying task. Nevertheless there are enough features of the original description (broad head; large eyes; densely punctate, opaque head; petiolar profile similar to that of P. wessoni) to support synonymy under P. oculatus.