Pseudomyrmex hospitalis

Known only from a few collections.

Identification
Ward (1999) - P. hospitalis can be distinguished from Pseudomyrmex gracilis by the shorter, broader petiole (see also PLI and PWI indices), shorter legs, and by the presence of thick black setae intermingled with finer, pale silvery pilosity on the head, mesosoma and petiole. In P. gracilis such black setae are absent from the propodeum and petiole, and less conspicuous on the head and pronotum. Other species, not associated with Tachigali or Triplaris, with which P. hospitalis might be confused are Pseudomyrmex maculatus (F. Smith), which is widespread in South America (Kempf, 1958), and Pseudomyrmex reconditus Ward. Both of these have conspicuous black setae on the mesosoma and petiole, but the petiole and legs are longer (PLI 0.57–0.64, PL/HW 0.52–0.57, LHT/HW 0.83–0.87, compared to 0.67–0.70, 0.47–0.49 and 0.78–0.79, respectively, in P. hospitalis) and the overall body size is smaller (HW 1.47–1.67, compared to 1.76–1.84 in P. hospitalis). In addition P. maculatus is a bicoloured orange-and-black species, with a thinner petiole (PWI 0.43–0.51). These differences must be considered tentative since so few specimens are known of P. hospitalis and P. reconditus. Finally, there are two problematic collections of large (HW 1.82–2.12), black, hospitalis-like workers (1 worker from Jatun Sacha, Ecuador and 3 workers from P. N. Manu, Peru) which have black setae on the mesosoma and petiole, but have the petiole shape and leg length of P. maculatus (PLI 0.59–0.60, PL/HW 0.52–0.54, LHT/HW 0.84–0.87).

Distribution
This taxon was described, and is only known, from Peru.

Biology
P. hospitalis is known only from two collections, both from Tachigali. The type series was collected in two different petiole domatia on a single branch of a Tachigali tree, which was also inhabited by Camponotus rectangularis. The workers were not particularly aggressive. It is possible that this species bears the same relationship to Tachigali as Pseudomyrmex nigropilosus (Emery) does to swollen-thorn acacias in Central America (Janzen, 1975), i.e., it may be a timid and unprotective species which opportunistically colonizes trees that are not inhabited by their usual aggressive occupants. P. hospitalis is the species previously referred to as Pseudomyrmex sp. PSW-35 in Ward (1991:340) and Ward (1993:161).

Nomenclature

 *  hospitalis. Pseudomyrmex hospitalis Ward, 1999b: 522, figs. 39, 40 (w.) PERU.

Worker
Measurements (n=5). HL 1.70–1.81, HW 1.76–1.84, MFC 0.060–0.076, LHT 1.37–1.46, CI 1.02–1.04, REL 0.61, REL2 0.58–0.60, FCI 0.03–0.04, FI 0.42–0.43, PLI 0.67–0.70, PWI 0.55–0.59.

With the traits of the gracilis group (i.e. palp formula 6,4; masticatory margin of mandible with 7–10 teeth; median clypeal lobe laterally rounded; eyes large and elongate; standing pilosity common on mesosoma dorsum and on external faces of tibiae; pronotum dorsolaterally submarginate) and the following more specific features. Relatively large species (see worker HW and LHT values); head broad, as wide or wider than long; anterior margin of median clypeal lobe straight to slightly convex; frontal carinae separated by less than basal scape width; in lateral view mesonotum more steeply inclined than dorsal face of propodeum; dorsal face of propodeum longer than declivitous face, and rounding insensibly into it; legs relatively short, LHT/HW 0.78–0.79; petiole relatively high and broad (see PLI and PWI values) with short anterior peduncle. Mandible subopaque, with scattered coarse punctures and fine striolate sculpture; head and mesosoma densely but finely punctulate-corarious to corarious-imbricate, subopaque to sublucid. Standing pilosity abundant, a mixture of fine pale silvery-white hairs and thicker, longer black setae; latter visible in profile on the head, mesosoma, petiole, and postpetiole. Dense covering of fine, appressed, silvery pubescence on most of body. Colour black; mandibles and frontoclypeal complex yellow-brown, antennae and legs dark brown, becoming lighter at their termini.

Type Material
Holotype worker. PERU, San Martin: 8 km ENE Tarapoto, 6°27’S, 76°18’W, 700 m, 19.viii.1986, ex Tachigali, P. S. Ward# 8612. HW 1.84, HL 1.79, EL 1.10, LHT 1.46, PL 0.91, PH 0.63.

Paratypes. Same data as holotype: series of nine workers (,, MCZC, , , ).