Perissomyrmex

It seems the genus Perissomyrmex has an ancient origin before the separation of American and Asian old lands. During the long evolutionary history, the genus changes slightly in morphology. At present time, the genus is limited in species number, rare in individual amount, living mainly in the high altitude mountainous habitats, and distributed in the Oriental and Neotropical Regions. (Xu and Zhang 2012)

Identification
Xu and Zhang (2012) - The genus Perissomyrmex is most similar to Pristomyrmex in the tribe Myrmecinini, but mandibles rectangular, with two basal teeth on the masticatory margin; clypeus without longitudinal central carina; antennae nine-segmented; antennal scrobes absent; pronotum without teeth; anteroventral corner of mesopleuron not extruding; propodeal lobes short and obtuse at apices; sting usually not extruding; head and mesosoma striate.

Species richness
Species richness by country based on regional taxon lists (countries with darker colours are more species-rich). View Data



Nomenclature

 *  PERISSOMYRMEX [Myrmicinae: Myrmecinini]
 * Perissomyrmex Smith, M.R. 1947i: 281. Type-species: Perissomyrmex snyderi, by original designation.

Xu & Wang (2004) - The ant genus Perissomyrmex was established by Smith in 1947 based on the type-species Perissomyrmex snyderi Smith intercepted in quarantine in New Jersey, U. S. A., ostensibly on a ship from Guatemala. But there is no hard evidence that Guatemala is the original home of the genus. Along with the discovery of a second species of the genus from Bhutan, Bolton (1981) suspected that South America is not the place of origin and the specimen of the type-species were brought to the U. S. A., via Guatemala, from somewhere in the Oriental region, or possibly the Indo-Australian region, by human commerce. The second species of the genus, P. monticola, was described by de Andrade in 1993. Baroni Urbani and de Andrade (1993) also considered the new Bhutanese species added strong weight to the hypotheses of an Old World natural habitat for Perissomyrmex and to its accidental introduction in both previously recorded American localities (Guatemala + New Jersey). However, Longino et al. (1994) reported that P. snyderi is native to Central America and its worker caste is polymorphism, this result provided a powerful evidence for the Central American origin of the genus. During the investigation of ant species-diversity in Ailao Mountain Nature Reserve of Yunnan Province, the third species of the genus, P. fissus was discovered in a ground sample in the primary sub-alpine moist evergreen broad-leaf forest at the altitude of 2500 m.

Worker
Xu and Zhang (2012) - Weakly dimorphic terrestrial myrmicine ants with the following combination of characters.

1. Head nearly square, slightly divergent forward.

2. Mandibles elongate and roughly rectangular; inner margin long, with distinct triangular tooth; masticatory margin short, with apical tooth, subapical tooth, diastema, and basal tooth.

3. Palp formula 4, 2.

4. Anterior clypeal margin protruding, with developed teeth or lobes, and significantly notched or depressed between teeth or lobes; posterior extension between antennal sockets roughly triangular.

5. Frontal lobes absent; frontal carinae poorly developed.

6. Antennal sockets exposed.

7. Antennae nine-segmented, scapes reach to or surpass occipital corners; antennal clubs three-segmented.

8. Antennal scrobes absent.

9. Eyes developed and convex, situated at about midpoints of lateral sides of head, or slightly behind midpoints.

10. Promesonotal profile is a convexity distinctly higher than propodeum.

11. Promesonotal suture present and weakly impressed.

12. Metanotal groove deeply depressed.

13. Propodeal spines developed, long and acute.

14. Propodeal spiracles circular, situated in middle of lateral surfaces of propodeum.

15. Propodeal lobes short and obtuse at apices.

16. Petiole pedunculate anteriorly, the petiolar spiracles situated at about midlength of peduncle; petiolar node roughly triangular or trapezoidal, with distinct anterodorsal corner, posterodorsal corner usually indistinct and rounded. Subpetiolar process usually reduced, sometimes weakly toothed.

17. Postpetiolar node roughly triangular and strongly inclined backward, anteroventral corner of postpetiole toothed.

18. Head and mesosoma usually strongly striate.

19. Pilosity abundant.