Pseudomyrmex kuenckeli

An uncommon encountered species with a large range.

Identification
Pseudomyrmex kuenckeli is a very distinctive species, immediately recognizable by its broad head, widely separated frontal carinae, posteriorly positioned eyes, abundant standing pilosity in the worker, flattened and laterally submarginate dorsal face of worker propodeum, and short broad petiole with keel-like venter. The queen is about the same size as the worker (HW 1.28–1.36, HL 1.18–1.26, LHT 0.97–1.03, in a sample of four queens), a situation not found in most Pseudomyrmex species (including other members of the viduus group). (Ward 1999)

Distribution
Mexico to Argentina and Brazil.

This taxon was described from Costa Rica.

Biology
Ward (1993) - P. kuenckeli appears to have a preference for nesting in large dead branches, in somewhat open or seasonally dry forest. Its association with ant acacias is sporadic at best and based upon two records from Costa Rica: Emery (1891:168) reported a single specimen collected by Alfaro from a swollen-thorn acacia, and Menozzi (1927b) recorded a collection by H. Schmidt from Acacia "spadicigera" (probably a misidentification of A. collinsii) near San Jose. (Ward 1993)

Ward (1999) - Tends to be associated with forests in which there is a more or less pronounced dry season. P. kuenckeli has large, aggressive, and apparently polygynous colonies, that occupy dead branches of a variety of woody plants. Additional details on behaviour and biology can be found in Forel (1899:89), Wheeler (1901:203–204), and Kempf (1961:405). Although there are old collections from swollen-thorn acacias in Costa Rica (see Ward, 1993:159) it is not clear if these were from living thorns. P. kuenckeli has not been found inhabiting any of the ant-plants associated with other members of the viduus group (Cordia, Tachigali, Triplaris, etc.).

Nomenclature

 *  kuenckeli. Pseudomyrma kuenckeli Emery, 1890b: 62, pl. 6, fig. 5 (w.q.) COSTA RICA. [Also described as new by Emery, 1894k: 51.] Combination in Pseudomyrmex: Kusnezov, 1953e: 214. Senior synonym of bierigi, crenulata, dichroa: Kempf, 1961a: 402. See also: Ward, 1993: 158; Ward, 1999b: 493.
 * dichroa. Pseudomyrma kuenckeli var. dichroa Forel, 1904c: 41 (w.) COLOMBIA. Junior synonym of kuenckeli: Kempf, 1961a: 402.
 * bierigi. Pseudomyrma kuenckeli var. bierigi Santschi, 1932e: 412 (w.) PANAMA. Junior synonym of kuenckeli: Kempf, 1961a: 402.
 * crenulata. Pseudomyrma crenulata Enzmann, E.V. 1944: 84, pl. 2, fig. 22 (w.) MEXICO. Junior synonym of kuenckeli: Kempf, 1961a: 402.

Worker
Ward (1999) - Measurements (n=16). HL 1.11–1.31, HW 1.21–1.51, MFC 0.133–0.178, LHT 1.07–1.32, CI 1.08–1.16, REL 0.44–0.48, REL2 0.39–0.42, FCI 0.10–0.13, SI 0.47–0.50, FLI 2.02–2.49, FI 0.31–0.37, PLI 1.01–1.28, PWI 1.08–1.40, PPWI 1.59–1.80.

Relatively large species (HW > 1.20, LHT > 1.05). Masticatory margin of mandible with six or (less commonly) seven teeth. Palp formula 6,4. Median clypeal lobe anterolaterally rounded, its anteromedial surface deflected ventrally. Frontal carinae widely separated (PFC and MFC > 0.12) and subparallel (PFC ≈ MFC), the distance between them much greater than basal scape width. Median lobe of antennal sclerite moderately exposed (PFC/ASD 0.63–0.77). Scape long and slender for the species group (SI > 0.46, SI2 1.14–1.27). Funiculus only moderately expanded apically, the terminal segment about 1.2–1.5 times the width of the first segment; funicular segment 2 longer than broad; funicular segments 3–10 as long as broad or slightly broader than long. Eye relatively small (see REL and REL2 values), only moderately elongate (OI 0.61–0.66), situated on posterior third of head. Head conspicuously broader than long (CI > 1.05), the sides diverging to a maximum width behind the eyes, then rounding gradually into the straight posterior margin. Mesosoma dorsum more or less flattened, especially the dorsal face of propodeum; metanotal groove broad but shallow (MP 0.013–0.044, MPI 0.011–0.034). Dorsal face of propodeum laterally submarginate, equal to or longer than the declivitous face (PDI 0.98–1.09), and meeting the latter at a relatively distinct angle of about 120°. Profemur slender. Legs relatively long, LHT/HL 0.92–1.03. Petiole very short and broad, as high as or higher than long (PLI > 1.00), with a weakly differentiated anterior peduncle, followed by a straight and steeply ascending anterior face which merges into the convex posterodorsal face; summit of node behind midpoint of petiole length (NI 0.52–0.58). Petiole venter keel-like, with a prominent, blunt anteroventral tooth or lobe and a variably developed (sometimes absent) posteroventral process. In dorsal view, petiolar node broadly transverse and laterally submarginate, tending to be trapezoidal or subrectangular in shape; minimum width of petiole (at the anterior peduncle) notably less than half the maximum petiolar width (PWI3 0.34–0.46), petiolar spiracles usually not prominent in dorsal view. Postpetiole globular, much broader than long (PPWI > 1.55); anteroventral process of postpetiole not developed. Mandible usually sublucid, with scattered elongate punctures and variable (sparse to dense) fine striolation overlying the otherwise smooth and shiny integument. Head, mesosoma, petiole, postpetiole and gaster lucid or sublucid, with numerous very fine punctures, mostly less than 0.010mm in diameter (coarser punctures present anteromesial to the compound eye and on parts of the mesosoma). Standing pilosity abundant, the hairs long and very conspicuous (MSC approximately 95–150, HTC 25–50); standing and decumbent setae present on the posterior margin and sides of head. Appressed pubescence also well developed and conspicuous on most of body, including the head; appressed hairs on abdominal tergite IV separated by much less than their lengths. Body varying in colour from orange-brown to dark-brown; when dark brown then part or all of the head and distal portions of the legs may be a constrastingly lighter orange- or yellow-brown.

Type Material
Ward (1993, 1999):

Syntype workers, queens, Alajuela, Costa Rica (A. Alfaro) [Examined].

Pseudomyrma kuenckeli var. dichroa Forel 1904:41. Syntype workers, Dibulla, Colombia (A. Forel) (,, MCSN, , , ) [Examined].

Pseudomyrma kuenckeli var. bierigi Santschi 1932:412. Holotype worker, Juan Diaz, Panama (A. Bierig) (NHMB) [Examined].

Pseudomyrma crenulata Enzmann 1945:84. Holotype worker, "Guernavaca", Mexico (not in MCZC) [Not examined; but other P. kuenckeli workers in the MCZC from Cuernavaca, Mexico (Wheeler) evidently represent the source series].