Bariamyrma

Only known from a few widely scattered collections of single queens of a single species - Bariamyrma hispidula.

Identification
Lattke's (1990) discussion of placement of the genus in relation to other Mymricinae is helpful for making determinations:

The placement of this genus of apparently lower Myrmicinae into established tribes or genus groups at this moment is not clear. On account of its apomorphies it is obviously not a member of the Myrmica nor Tetramorium genera groups. If we consider the Pheidologeton group and the characters listed by Ettershank (1966: 115) as well as those pointed out by Bolton (1987: 265) there seems to be no affinity. The lack of a clearly defined antennal club and presence of well developed frontal carinae in Bariamyrma plead against such a grouping. The only other universal characters within pheidologetines are the lack of a prominent median clypeal seta and a closed radial cell of the fore wing, but both are plesiomorphic states and of limited phylogenetic value. To place it in the Pheidolini or Myrmecini, polyphyletic assemblages of genera, would be of no heuristic value.

The specimen does share a number of characters with Lordomyrma such as the mandibular structure, convex clypeus, frontal lobes, frontal carinae, antennae, and propodeal spiracles set well forward from the margin of the declivity. Yet in Lordomyrma the clypeus is clearly bicarinate, and distinct, albeit flat, antennal scrobes are formed. In this genus the petiolar peduncle tends to be shorter, the humeral angles somewhat sharper, tibial spurs are wanting, the sting presents no flange and the propodeal spiracle is below the base of the propodeal spine. Wheeler (1919: 105) illustrates the forewing of a male Lordomyrma and it is quite similar to Bariamyrma except for the anal vein, which does not extend beyond cu-a. Wheeler also notes the presence of hairy wings. A survey of the other genera related to Lordomyrma, such as Cyphoidris Weber, Lachnomyrmex Wheeler, Dacetinops Brown & Wilson, and Indomyrma Brown reveals distinct antennal scrobes and clubs, the lack of apical spurs on the meso- and metatibiae, and a raised, usually bicarinate, median clypeus. The sting in Lachnomyrmex tends to be flattened, and in Cyphoidris terminates in a narrow spatulate appendage. Lachnomyrmex has its propodeal spiracles set well back from the declivitous face margin, but Cyphoidris and Dacetinops have them positioned quite posterad. Accepting Bariamyrma as a member of this assortment of genera, and even though it has several apomorphies in relation to them, such as the reduced palpal segmentation and form of the sting, on the whole it seems that Bariamyrma is a somewhat primitive member of the group.

Distribution
Known from Costa Rica, Paraguay and Venezuela.

Castes
Described and only known from the queen caste.

Nomenclature

 *  BARIAMYRMA [Myrmicinae: Stenammini]
 * Bariamyrma Lattke, 1990a: 173. Type-species: Bariamyrma hispidula, by original designation.

Queen
Ants belonging to the subfamily Myrmicinae.

1. Mandibles triangular, with a series of 9 teeth on the masticatory margin, the apical tooth being the largest.

2. Palp formula 3,2 (in situ count).

3. Anterior clypeal border convex, medially produced into a blunt point and covering basal mandibular margins.

4. Clypeus posteriorly narrowly inserted between the widely separated frontal lobes.

5. Clypeus with longitudinal rugae, not distinctly bicarinate but with a prominent anteromedian carina.

6. Lateral portions of clypeus not posteriorly raised into a shield-wall in front of the antennal fossae.

7. Anterior margin of clypeus with hairs but without a single prominent median seta.

8. Frontal carinae extend posteriorly to slightly behind the eyes; almost as long as the scapes and posteriorly diverging one from another.

9. No evident antennal scrobe present.

10. Antennae with 12 segments, funiculus clavate with a vague 3-merous club; each funicular segment sharply constricted one from another.

11. Frontal triangle well defined, smooth and shining.

12. Propodeal spiracle situated slightly above mid-height of sclerite, close to junction of metapleuron and anterad of teeth, well back from the edge of the declivitous face.

13. Declivitous propodeal face with a pair of sharply pointed triangular lateral teeth joined by carinae to the well developed, bluntly pointed inferior propodeal plates.

14. Posteroventral alitrunk with a median convex emargination, not open and extending anterad of hind coxae.

15. Metasternal process absent.

16. Strongly pedunculate petiole, node conical with a bluntly pointed apex, petiolar ventrum with a low longitudinal carina, no prominent process.

17. Petiolar spiracle is at mid-peduncular length.

18. Postpetiolar node dome-shaped as seen laterally, and campaniform dorsally; prominent transverse sub postpetiolar process.

19. Sting weakly sclerotized and ending in a prominent lobular flange.

20. Apex of meso- and metatibiae each with a single simple spur.

21. Strongly sculptured cuticle except for gaster.

Features of the anterior wing venation include Mf1 branching out quite distad of cu-a, the absence of lr and r-m, the continuity of 2r and Rsf2-3. One cubital cell is present and the radial cell is closed. The posterior wing has only one cell, neither Rs, M, nor CuA extends after r-m, and M-Cu does not reach the wing base. A thickened cu-a reaches toward but does not touch the brief and thick anal vein. Wings with abundant decumbent pilosity, borders of posterior wings with a fringe of short hairs, but such a fringe lacking about the anterior wings.

Etymology
The generic name Baria is the name of a river next to the Cerro Neblina expedition basecamp.