Pseudomyrmex hospitalis

AntWiki - Where Ant Biologists Share Their Knowledge
Jump to navigation Jump to search
Pseudomyrmex hospitalis
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Pseudomyrmecinae
Genus: Pseudomyrmex
Species: P. hospitalis
Binomial name
Pseudomyrmex hospitalis
Ward, 1999

Pseudomyrmex hospitalis casent0005839 profile 1.jpg

Pseudomyrmex hospitalis casent0005839 dorsal 1.jpg

Specimen labels

Known only from a few collections.


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 based on Regional Taxon Lists

Neotropical Region: Peru (type locality).

Distribution based on AntMaps


Distribution based on AntWeb specimens

Check data from AntWeb


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).



The following information is derived from Barry Bolton's New General Catalogue, a catalogue of the world's ants.

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

Unless otherwise noted the text for the remainder of this section is reported from the publication that includes the original description.



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 (Museum of Comparative Zoology). 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 (The Natural History Museum, Los Angeles County Museum of Natural History, MCZC, Museo de Historia Natural, Museu de Zoologia da Universidade de Sao Paulo, Philip S. Ward Collection).


  • Ward, P. S. 1999b. Systematics, biogeography and host plant associations of the Pseudomyrmex viduus group (Hymenoptera: Formicidae), Triplaris- and Tachigali-inhabiting ants. Zool. J. Linn. Soc. 126: 451-540 (page 522, figs. 39, 40 worker described)