Pogonomyrmex mayri

A relatively well studied species (Kugler 1979, Kugler and Hincapié 1983, Kugler 1984) that only occurs in northeastern Columbia.

Identification
Johnson (2015) - Worker and Queen Pogonomyrmex mayri is a monotypic species-group (P. mayri-group) in which all three castes are easily diagnosed. Workers are diagnosed by: (1) striae on first gastral tergum, (2) psammophore poorly-developed, consisting of numerous short hairs scattered across ventral side of head, (3) deeply incised sculpturing on head and mesosoma, (4) antennal scapes densely granulate-punctate with strongly flattened base, (5) superior and inferior propodeal spines long, acuminate, (6) posterior surface of petiolar node flattened, and (7) anterior margin of clypeus concave with a small medial tooth. Queens are diagnosed by: (1) ergatoid, with ocelli not visible or absent, (2) striae on first gastral tergum, (3) postpetiole enlarged (PPW > 1.20 mm), wider than long, (4) anterior clypeal margin with medial tooth, and (5) anterior surface of petiolar node striate.

Male This caste is diagnosed by: (1) CI < 75.0, (2) neck elongate, flattened dorsally (3) in dorsal view, postpetiole >1.5x as long as wide, (4) in dorsal view, petiolar node elongate (>2x as long as wide), (5) funiculi with numerous suberect hairs, and (6) notauli absent, presence indicated only by short black lines that indicate underlying apophyses.

Pogonomyrmex mayri is a distinctive species that is easily diagnosed by the above characters. Pogonomyrmex naegelii is the only congener known to occur in Colombia.

Distribution
Pogonomyrmex mayri is only known to occur in northeastern Colombia in the Guajira-Barranquilla Xeric Scrub and Sinú Valley Dry Forest ecoregions as defined by Olson et al. (2001), with one additional record from the Magdalena-Urabá Moist Forests ecoregion.

Distribution based on Regional Taxon Lists
Neotropical Region: Colombia.

Habitat
P. mayri appears to be restricted to desert and dry deciduous forest habitats, mostly below 200 m, on the northwestern, western, and possibly southern end of the Sierra Nevada de Santa Marta, but it is also known to occur in more mesic habitats at elevations up to 835 m (Guerrero & Sarmiento, 2010; Kugler, 1979, 1984; Kugler & Hincapie, 1983).

Biology
Johnson (2015) - Pogonomyrmex mayri is one of the more well-studied South American species of Pogonomyrmex. This is a phylogenetically basal species in the genus that is most closely related to P. sylvestris-group species (C. S. Moreau & R. A. Johnson, unpub. data).

Nests are typically located in soil at the base of trees or shrubs, or occasionally in cracks at the base of rocky outcrops or high on sandy beaches. Nests have one large (1–3 cm diameter), irregularly-shaped entrance, and the nest is normally covered by dry leaves, a log, or a stone; the nest lacks a crater, mound, or tumulus. Nests contain two to three chambers and range from 15–22 cm deep. Nest density ranges from approximately 50–150/ha; density decreases at elevations >100 m (Kugler & Hincapie, 1983).

Workers of P. mayri are diurnal scavengers that forage on the surface of the leaf litter or bare soil. Diet varies seasonally; more insects (especially termites and isopods) are harvested during the wet season (probably because of increased availability), while flower and leaf fragments are more commonly harvested during the dry season. Dead and dry arthropods comprise >50% of the harvested items in both seasons, but larger insects that struggle are avoided; seeds account for a small portion of the diet (ca. 10%) regardless of season. Colonies are small and consist of from 200–900 workers plus 25–270 larvae and pupae, and up to 28 males. Thus, overall colony size ranges from 284–1020 individuals (Kugler, 1984; Kugler & Hincapie, 1983).

No information is available on timing or location of mating flights or method of colony founding. However, males are relatively common in nest excavations, and they have been collected on vegetation outside the nest in March, April, June, September, October, and November; this suggests that P. mayri has a very different type of mating flight and mating behavior than is known for all congeners. Colonies have one ergatoid queen (known from 2 of 10 excavated colonies). Nothing is known about production of ergatoid queens (Kugler & Hincapie, 1983). Interestingly, ocelli were not visible on either of two examined ergatoid queens indicating that the ocelli are vestigial or absent, and Kugler (1979) did not mention ocelli in his description of the ergatoid queen.

Nomenclature

 *  mayri. Pogonomyrmex (Janetia) mayri Forel, 1899c: 61 (footnote) (w.m.) COLOMBIA. Kugler, C. 1979a: 170 (q.); Wheeler, G.C. & Wheeler, J. 1953a: 112 (l.). Combination in P. (Forelomyrmex): Wheeler, W.M. 1913a: 80. See also: Kugler, C. & Hincapié, 1983: 190.

Worker
Johnson (2015) - Lectotype (n = 12). HL 2.12 (1.78–2.19); HW 1.90 (1.63–1.94); MOD 0.31 (0.26–0.30); OMD 0.47 (0.45–0.55); SL 1.63 (1.50–1.74); PNW 1.47 (1.13–1.34); HFL 2.60 (2.03–2.71); ML 2.55 (2.13–2.49); PW 0.37 (0.34–0.43); PPW 0.69 (0.54–0.70). Indices: SI 85.79 (77.72–104.82); CI 89.62 (87.69–96.63); OI 16.32 (14.51–16.96); HFI 136.84 (121.56–140.41). See also Kugler (1979).

Head weakly elongate to elongate (CI = 87.69–96.63), widest just posterior to eyes, narrowing to vertex; posterior margin strongly concave medially, broadly V-shaped. Cephalic dorsum, sides, and vertex rugose, rugae variable in height; in full-face view, medial rugae not diverging toward posterior corners of head. Cephalic rugae deeply incised, interrugae strongly granulate, dull. Anterior margin of clypeus convex with medial triangular tooth, dorsum of clypeus with numerous subparallel, wavy, longitudinal rugae similar to those on cephalic dorsum. Mandible with six teeth; mandibular dorsum coarsely rugose. Up to several moderately long, curved, bristle-like, amber to brownish hairs project from anterior margin of clypeus and basolateral margin of mandibles. Eyes small, MOD = 0.13–0.17x HL. In profile, eyes situated anterior to middle of head, OMD = 1.52–2.00x MOD; no hairs project from between ommatidia. Antennal scapes long (SI = 77.72–104.82), reaching to surpassing vertex by less than length of basal funicular segment; entire scape with weak longitudinal striae, interstriae strongly granulate, dull. Basal flange of scape well-developed with recurved, carinate margin. Psammophore poorly-developed, consisting of numerous short hairs scattered across ventral side of head.

Mesosomal profile strongly convex; all mesosomal surfaces with wavy, deeply incised rugae that vary in height. Transverse rugae on pronotal sides curving dorsally, anteriorly, and posteriorly, transverse rugae on pronotal collar; dorsum of propodeum with transverse rugae that traverse to propodeal spiracle then angle posterad over metapleural lobe. Superior propodeal spines long, acuminate, bases connected by well-defined keel, spines longer than distance between their bases; inferior propodeal spines well-developed, acuminate, length approximately 0.3–0.5x that of superior spines; declivitous surface of propodeum transversely rugose. Propodeal spiracles narrowly ovate facing posterad. Rugae and interrugae on mesosoma strongly granulate, dull. Legs strongly granulate, dull.

Peduncle of petiole about 0.5x as long as petiolar node, anteroventral margin varying from broad translucent process to triangular acuminate spine. In profile, petiolar node asymmetrical with anterior surface approximately one-half as long as posterior surface, apex angulate, posterior surface flattened; all surfaces rugose. In dorsal view, petiolar node elongate, approximately twice as long as wide, lateral margins weakly convex posteriorly, nearly vertical medially, concave anteriorly, anterior one-third narrowing to acuminate tip; anterior portion of posterior surface weakly depressed below margins. Dorsum of postpetiole convex in profile, anterior margin narrowing to helcium; robust in dorsal view, longer than wide; widest near posterior margin, narrowing to truncate anterior margin; dorsum and sides coarsely rugose; ventral process strongly granulate, dull. Rugae and interrugae on posterior surface of petiolar node and dorsum of postpetiole strongly granulate, dull. First gastral tergum with fine longitudinal striae, dull.

Short to long, erect, amber to brownish hairs abundant on head, longest >MOD; mostly medium-length hairs abundant on mesosoma, petiole node, postpetiole, and gastral terga, longest approaching MOD. Scape with abundant medium-length, suberect hairs; abundant subdecumbent hairs on funicular segments. Legs with moderately abundant, short to medium-length, suberect setae. Body concolorous dark reddish-brown to dark brownish-black, or with postpetiole, gaster, legs slightly lighter reddish-brown.

Queen
Kugler (1979) - (for each measurement, that of the first specimen is followed by that of the second) Mandibles subtriangular; basal and masticatory borders meet at obtuse angle; outer border gently convex, slightly flattened midlength; masticatory border with 5 teeth increasing in size apically, the second tooth with a denticle on its distal edge (second specimen with denticle reduced on one mandible, absent on the other). Palpal formula 3,3 as determined from undissected specimens; neither palp reaching posterior margin of buccal cavity. Labrum with rounded lobes on either side of a sharp median emargination. Head about as wide as long; in full face dorsal view occiput broadly Vshaped, with distinct occipital lobes; sides of head gently convex on temples to small bulge behind the eye, then indented to flat cheeks. Middle of clypeus weakly convex overall, both transversely and longitudinally; sculpture stops a weak median carina short of reaching apron; apron narrow, leading edge convex with median tooth bracketed by low rounded lobes; lateral arms form low narrowly rounded ridges in front of antennal fossae. Frontal triangle reduced to a narrow, deep Y-shaped sulcus separating clypeus from posterior 3/4 of frontal lobes. Frontal lobes short, well separated; carinae convex. Eyes small, convex, ringed by a round bottom sculptured groove.

Antennae 12-merous. Scape short and rather thick, not reaching vertex of head; bent at a nearly right angle within basal 1/4 of length and largely flat beyond (extensor surface viewed from side). First 2 segments of flagellum longer than wide, L 0.21, 0.20; 0.18, 0.18; segments 3-7 wider than long; segments 8-11 about as long as wide. Apical segment much longer than any other, L 0.34, 0.37; apex narrowly rounded. Last 4 segments constitute a weakly define antennal club. Width of flagellar segments increases uniformly from first (0.13, 0.12) to last (0.18, 0.20). Trunk in full dorsal view with complete, fine, immobile, promesonotal suture; mesonotum bisected at about 2/3 of length by a faint shallow sulcus (probable rernnant of scutoscutellar suture) which drops out at lateral margins; metanotum reduced to a sharp groove between mesonotum and propodeum. Propodeal spines robust, acute, their bases widely separated by a broad concavity. Propodeal spiracles prominent; their orifices circular, facing posterolaterad.

From the side dorsal profile convex; mesonotum set off by grooves, its outline higher and more convex than pronotum and propodeum. Distinct sutures separate pronotum and mesonotum from mesopleura; metapleura delimited by weak sulci scarcely distinguishable from the sculpture, expecially in areas anterior to the spiracle. Metapleural gland bulla well developed. Inferior propodeal plates broad, blunt. Dorsal face of propodeun curves broadly into declivous face.

Petiole robust, with broadly conical anterior peduncle and weakly differentiated posterior peduncle. Venter seen from below with 3 longitudinal ridges running from short acute tooth to posterior peduncle. Node in side view with flat anterior face (except for 2 low undulations) joining anterior peduncle at about a 135-degree angle, meeting dorsal face of node at an acute angle; dorsal face flat, broadly curving into short posterior face. Outline of node from above ovoid, slightly wider than long, widest just caudad of midlength. Anterior edge sharp (with low upturned burr in second specimen), gradually softening to broadly rounded along sides.

Postpetiole large, inflated; connection with gaster broad. In lateral view, dorsum strongly and evenly convex; venter much shorter than dorsum, profile undulate, anterior lip broadly rounded. From directly above node subtrapezoidal; posterior edge a broad convex arc somewhat flattened mesad, posterior corners broadly rounded, sides flat, tapered to corners of weakly concave anterior edge.

Gaster greatly enlarged, subglobose, heavily sclerotized, slightly longer than wide and slightly wider than deep; widest at midlength. Sclerites not fused, but rigidly articulated. Measured from side along axis, first tergum covers 90% of length of gaster; first sternum 53%.

Legs neither long and slender nor very robust. Femur lengths front to back 1.48, 1.50; 1.45, 1.45; 1.64, 1.65 mm,not incrassate (W/L 18, 18; 17, 18; 16, 16%). Hind tibia length 1.33, 1.48 mm. Middle and hind tarsi each with one short simple apical spur. Hind metatarsus 1.16, 1.29 mm; tarsal claws simple.

Most of body with fine dense punctulate striae overlain by a coarse broken wavy sculpture: clypeus, top, sides and back of head, trunk (except those areas listed below), petiolar node and postpetiole. In other places the overlying sculpture is much reduced or absent, leaving largely flat surfaces of fine, punctulate striae: gula (some weakly undulate sculpture present), anterior face of pronotum, prosternum, forecoxae, dorsomedial surfaces of metapleural gland bullae, declivous face of propodeum (striae coarser, less dense), most of first gastric segment (striae weaken caudad). Striation much reduced, leaving predominately fine, densely punctate surfaces on: antennae (striae present but finer than elsewhere and not predominate), legs except first coxae, and end of first and most of succeeding segments of gaster (narrow coriaceous margins on each). Mandibles finely longtitudinally striate, without punctures. Inner surface of mandibles, peduncle and venter of petiole smooth and shining; the latter with scattered punctures. Striation more or less longitudinal on mandibles, antennae, clypeus, dorsum and sides of head, mesonoturn, sides of trunk (though much confused in parts), coxae, anterior face and sides of petiolar node, sides and venter of postpetiole, and gaster. Striation essentially transverse on gula (bisected by median longitudinal ridge), pronotum, basal and declivous faces of propodeum (striae converge on apices of spines from all sides), dorsal surface of petiolar node, anterior and dorsal faces of postpetiole (transversely arcuate).

Whole body, except peduncle of petiole, covered with short, stiff, erect, acute golden hairs, interspersed with shorter, more flexuous recurved hairs. Apron of clypeus with longer flexuous hairs; hair on mandibles more decumbent. No psammophore of any sort. Color uniformly dark ferruginous brown, except for brown to yellow apical antennomere.

Johnson (2015) - (n = 2). HL 1.50–1.51; HW 1.44–1.52; MOD 0.27–0.28; OMD 0.43–0.47; SL 1.03–1.14; PNW 1.14–1.18; HFL 1.64–1.65; ML 1.99–2.02; PW 0.70–0.74; PPW 1.20–1.25. Indices: SI 71.53–75.00; CI 96.00–100.66; OI 18.42–18.75; HFI 108.55–113.89.

Male
Johnson (2015) - (n = 10). HL 1.49–1.72; HW 1.06–1.23; MOD 0.30–0.36; OMD 0.15–0.19; SL 0.22–0.37; HFL 1.47–2.03; ML 1.96–2.41; PW 0.28–0.36; PPW 0.50–0.65. Indices: SI 20.18–34.91; CI 66.25–74.52; OI 27.52–32.08; HFI 134.51–178.30.

Male
Kugler (1979) - (ranges from 5 individuals, including the largest and smallest available from 7 collections) TL 7.29-8.10; HL 1.56-1.74; HW just behind eyes 1.10-1.25 (CI 70-73); eye L 0.31-0.34; scape L 0.34-0.42; combined L of 2nd and 3rd flagellar segments 0.81-0.90; ML 0.12-0.19; WL 2.17-2.40; front wing L 4.00-4.10; hind femur L 1.86-2.00; petiole L 0.80-0.94; postpetiole L 0.72-0.93; gaster L 1.74-2.10.

Head remarkably elongate and flattened behind. Clypeus rather long, broadly convex in both dimensions, middle subsiding evenly to sides; free margin broadly arcuate except for slight median flattening or emargination, which possesses in some specimens a very small acute or rounded tooth that is a continuation of a weak median carina running the length of the clypeus. Frontal triangle triangular, with a broad, shallow, V-shaped impression. Frontal carinae reduced to rims encircling the sockets of the antennae. Palpal formula 4, 3. Scape much shorter than combined length of second and third flagellar segments. Scape and flagellum fairly densely covered with short erect hairs; segments 2-12 of flagellum also very densely endowed with fine appressed pilosity.

Trunk uniquely shaped and proportioned, as if the propodeum has grown forward, compressing the mesoscutum and pronotum, and rotating the neck and head to a more ventral position. Pronotum very constricted mesad. Mesonotum very short (mesoscutal L/ WL 20-23%); seen from the side evenly and rather strongly convex, from above nearly equilaterally triangular; with 2 short black lines that indicate underlying apophyses of the notauli. Middle of scutellum and metanotum raised into a prominent subcircular bulge. Propodeum elongate (propodeal L/ WL 49-52%), dorsal face curving insensibly into declivous face; unarmed. Petiole long, cylindrical, nodeless. Legs long and slender (hind femur L/ WL 83-86%); front coxae long, compressed front to back.

Wings evenly covered with fine hairs. Venation of fore wing variable. Of 154 wings (77 individuals) from 7 collections, the most common venation had a small closed discoidal cell with subequal sides, a hexagonal cubital cell with a narrow opening to the costal cell and sinuate lower edge (Rs), radial cell open distad, and veins Rs and M unjoined by a cross vein beyond the discoidal cell (121 wings). In 11 wings the discoidal cell was open distad, but otherwise the same. In 20 wings the discoidal cell was closed, but a cross vein (r-m) connected the Rs and M veins, creating a second cubital cell. That cross vein joined the Rs well proximad of the end of the first cubital cell, except in one wing where it was almost even with the end of the cell. Two wings had both open discoidal cells and the r-m cross vein. Wings of different venation commonly appear on the same individual.

Hypopygium in ventral view subtriangular; apex broadly rounded, proximal corners square with slender truncate lateral projections, middle of base with a long slender truncate anterior process. Gonostyli (=parameres) of genital capsule tapered in side view, but with apices broadly rounded; setae occur only around apices. Digitus long, slender, blunt, strongly down-curved; not reaching to apex of gonostylus. Cuspis short, pollicate when seen from the side. Aedeagus fairly slender, with serrate ventral margin; serrations decrease in size to apex. Apex narrow, blunt; half smooth, half finely serrate. Inner dorsal margins of gonocoxites form a long narrow, gently convex V.

Sculpture like that of worker and female, with the following exceptions: Striation on head largely transversely arcuate caudad of antennae, clypeus without coarse undulations. Trunk and petiole without overlying broken wavy sculpture; all but pronotum longitudinally striate. Striation on postpetiole gives way to purely punctate sculpture in caudal half. Gaster, first and second antennomeres, and legs smooth and shining, except for weakly striate fore coxae.

Etymology
Johnson (2015) - This species was named to honor Dr. Gustav Mayr, who erected the genus Pogonomyrmex in 1868.

References based on Global Ant Biodiversity Informatics

 * Behrmann N. B. E., F. A. Milesi, J. Lopez de Casenave, R. G. Pol, and B. Pavan. 2010. Colony size and composition in three Pogonomyrmex ant species (Hymenoptera: Formicidae) in the central Monte desert, Argentina. Rev. Soc. Entomol. Argent. 69 (1-2): 117-122.
 * Fernández F., E. E. Palacio, W. P. MacKay, and E. S. MacKay. 1996. Introducción al estudio de las hormigas (Hymenoptera: Formicidae) de Colombia. Pp. 349-412 in: Andrade M. G., G. Amat García, and F. Fernández. (eds.) 1996. Insectos de Colombia. Estudios escogidos. Bogotá: Academia Colombiana de Ciencias Exactas, Físicas y Naturales, 541 pp
 * Forel A. 1912. Formicides néotropiques. Part IV. 3me sous-famille Myrmicinae Lep. (suite). Mémoires de la Société Entomologique de Belgique. 20: 1-32.
 * Guerrero R. J., and C. E. Sarmiento. 2010. Distribución altitudinal de hormigas (Hymenoptera, Formicidae) en la vertiente noroccidental de la Sierra Nevada de Santa Marta (Colombia). Acta Zoologica mexicana (n.s.) 26(2): 279-302.
 * Johnson R. A. 2015. A taxonomic revision of South American species of the seed-harvester ant genus Pogonomyrmex (Hymenoptera: Formicidae). Part I. Zootaxa 4029(1):1-142
 * Johnson Robert. 2014. List of South American species of Pogonomyrmex. Accessed on February 5th 2014 at http://www.asu.edu/clas/sirgtools/pogonomyrmex/SOUTHAMERICANPOGOS.htm
 * Kugler C. 1979. Description of the ergatoid queen of Pogonomyrmex mayri with notes on the worker and male (Hym., Formicidae). Psyche (Cambridge) 85: 169-182.
 * Kugler C. 1984. Ecology of the Ant Pogonomyrmex mayri: Foraging and Competition Biotropica 16(3): 227-234.
 * Kugler C., M. del C. Hincapié. 1983. Ecology of the ant Pogonomyrmex mayri: distribution, abundance, nest structure, and diet. Biotropica 15: 190-198.