Charles Kugler.
Description of the Ergatoid Queen of Pogonomyrmex mayri with Notes on the Worker and Male (Hym., Formicidae).
Psyche 85(2-3):169-182, 1978.

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DESCRIPTION OF THE ERGATOID QUEEN OF
POGONOMYRMEX MAYRI WITH NOTES ON THE
WORKER AND MALE (HYM., FORMICIDAE)*
BY CHARLES KUGLER
Department of Entomology
Cornell University
Ithaca, New York 14853
During a recent stay in Santa Marta on the north coast of Colombia, I had the opportunity to study Pogonomyrmex mayri, the sole member of the subgenus Forelomyrmex, whose entire range is the desert and dry deciduous forest below 200 tn. on the northwestern, western, and possibly southern skirts of the Sierra Nevada de Santa Marta.
This ant was described by Fore1 (1899: 61-62, footnote) from worker(s) and male(s) he collected. Neither he nor subsequent entomologists, including P. J. Darlington, found females. The reason females were unknown became clear as I worked in the area and later began to look at the biology of P. mayri more closely. Though I collected males from vegetation nearly year around (3 Sept. to 30 June), no winged females were seen in two years. Furthermore, only after thoroughly excavating 10 nests were any females found at all, one in each of 2 nests dug by my coworker, Maria del Carmen Hincapik, and her assistant. Both were ergatoid nest queens.
This paper presents a formal description of those queens, notes on the worker and male supplementing Forel's original description, and a discussion of the taxonotnic status of Pogonomyrmex mayri. Notes on the biology of P. mayri will be reported later. *A report of research of the Cornell University Agricultural Experiment Station, New York State College of Agriculture and Life Sciences at Cornell University, Ithaca, New York 14853.
Manuscript received by the editor October 20, 1978.



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Psyche
[June-September
QUEEN
(Figs. 1-4, Table 1)
Two specimens (Museum of Comparative Zoology at Harvard University) taken by Maria del Carmen Hincapik from nests in soil behind the beach at Bahia Gairaca, about 20 krn. by road east of Santa Marta, Colombia, in Parque Nacional Tayrona, on 2 dif- ferent days, April 2,2, 1978 (#780422-6) and April 26, 1978 (#780426-9). The following description is based primarily on the first specimen, with occasional remarks on the second if they differ in some way. 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 rnid- length; 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. Labrurn with rounded lobes on either side of a sharp median ernargination. Head (fig. 4) about as wide as long; in full face dorsal view occiput broadly V- shaped, 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 antenna1 fossae. Frontal triangle reduced to a narrow, deep Y-shaped sulcus separating clypeus from posterior 3/^ of frontal lobes. Frontal lobes short, well separated; carinae convex. Eyes small, convex, ringed by a round- bottom sculptured groove.
Antennae 12-rnerous. Scape short and rather thick, not reaching vertex of head; bent at a nearly right angle within basal '74 of length and largely flat beyond (extensor surface viewed from side). First 2 segments of flagellurn longer than wide, L 0.21, 0.20; 0.18, 0.18; segments 3-7 wider than long; segments 8-1 1 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 defined



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19781 Kugler - Pugonomyrmex mayri 171
Figs. 1-3.
Queen of Piipnomyrmex mayri. Fig. I, dorsal view. Fig. 2, lateral view. Fig, 3, lateral view of trunk and waist (waviness of some hairs is an artifact of charging).




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172 Psyche [June-September
antenna1 club. Width of flagellar segments increases uniformly from first (0.13, 0.12) to last (0.18, 0.20). Trunk in full dorsal view (fig. 1) with complete, fine, immobile, prornesonotal suture; rnesonoturn bisected at about 2/ 3 of length by a faint shallow sulcus (probable remnant of scutoscutellar suture) which drops out at lateral margins; rnetanoturn reduced to a sharp groove between rnesonoturn and propodeurn. Propodeal spines robust, acute, their bases widely separated by a broad concavity. Propodeal spiracles prominent; their orifices circular, facing pos- terolaterad.
From the side (figs. 2,3) dorsal profile convex; rnesonoturn set off by grooves, its outline higher and more convex than pronoturn and propodeurn. Distinct sutures separate pronoturn and rnesonoturn from rnesopleura; rnetapleura delimited by weak sulci scarcely distinguishable from the sculpture, expecially in areas anterior to the spiracle. Metapleural gland bulla well developed. Inferior pro- podeal plates broad, blunt. Dorsal face of propodeurn curves broadly into declivous face.
Petiole robust (figs. 1-3), 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' 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 rnidlength. 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, dorsurn strongly and evenly convex; venter much shorter than dorsurn, profile undulate, anterior lip broadly rounded. From directly above (not as in fig. 1) node subtrapezoidal; posterior edge a broad convex arc somewhat flattened rnesad, 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 rnidlength. Sclerites not fused, but rigidly articulated. Measured from side along axis, first tergurn covers 90% of length of gaster; first sternum 53%.




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19781 Kugler - Pogonomyrmex mayri 173
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 rnrn., not incrassate (W/L 18, 18; 17, 18; 16, 16%). Hind tibia length 1.33, 1.48 mrn. Middle and hind tarsi each with one short simple apical spur. Hind metatarsus 1.16, 1.29 rnrn.; tarsal claws simple. Most of body with fine dense punctulate striae overlain by a coarse broken wavy sculpture (figs. 1-4): 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 pronoturn, prosternurn, forecoxae, dorsornedial surfaces of rneta- pleural gland bullae, declivous face of propodeurn (striae coarser, less dense), most of first gastric segment (striae weaken caudad). Striation much reduced, leaving predominately fine, densely punc- tate 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 punc- tures. 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, dorsurn and sides of head, rnesonoturn, 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), pro- noturn, basal and declivous faces of propodeurn (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 psarnrnophore of any sort. Color uniformly dark ferruginous brown, except for brown to yellow apical antennornere.
WORKER
(Figs. 6-8)
The worker is most strikingly different from the queen in its jet black color, its larger head, and smaller waist and gaster. It appears



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174 Psyche [June-September
Figs. 4-5.
Fig. 4, Head of queen of P, mayri, nearly full dorsal view. Fig. 5, side of head and trunk of P. mayri male,




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19781 Kugler - Pogonomyrmex mayri 175
as if there is a longitudinal gradient of allornetric growth in the queen such that the anterior half grows slower than, and the posterior half faster than in the worker. A detailed description of how the worker differs from the queen follows (see also table 1). Head much larger, more elongate (fig. 6). Mandibles longer, with 6 distinct teeth and a low basal angle. Papal formula 4, 3. Median carina complete to marginal tooth, but low; seen best from postero- dorsal view. Eye smaller relative to size of head. Trunk more completely fused; profile evenly convex, with poorly differentiated Figs. 6-8.
Worker of P. mayri. Fig. 6, head in full dorsal view. Fig. 7, trunk and petiole in lateral view. Fig. 8, dorsal view of petiole.



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176 Psyche [June-September
neck and declivous propodeal face (fig. 7). Propodeal spiracle not prominent; orifice oval, facing caudad. Superior propodeal spines longer, spiniforrn; their bases narrowly separated. Inferior pro- podeal plates short, spiniforrn. Petiole (figs. 7, 8) low, narrow; anterior peduncle very slender in dorsal view, dorsoventrally cunei- form; no posterior peduncle; venter with 2 longitudinal ridges. Anterior ridge of petiolar node drawn out into an acute, dorso- ventrally flattened, somewhat upturned tooth; sides of node seen from above parallel, flat in anterior half, weakly convex in posterior half. Postpetiole smaller than in female, especially in width and height; more conical in dorsal view. Gaster much smaller in all dimensions. Legs longer, more slender; middle and hind tibia1 spurs finely pectinate. Sculpture on dorsurn of trunk not broken by sutures; transverse striae on anterior pronoturn become longitudinal on rnesonoturn, then transverse again on propodeurn. Striation on first tergurn of gaster fades at about rnidlength; much of caudal half smooth and shining. Color uniformly dull black in mature workers; callows dark ferruginous brown. Petiole, postpetiole and gaster less densely hairy than in female; color of erect hairs can vary from black to golden on any one individual.
The sting apparatus of the worker is most like those of P. (Ephebomyrmex) naegeli and P. (E.) imberbiculus (Kugler, 1978): anterior apoderne of spiracular plate wide and of uniform width along entire length of plate; lancets with 2 distinct barbs and no dorsal ridge; triangular plate without dorsal and medial tubercles; other parts as shown in Kugler (1978) figs. 1.8, 19, 21, 22, and 26. MALE
(Fig. 5)
Measurements (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 0.3 1-0.34; scape L 0.34-0.42; combined L of 2nd and 3rd flagellar segments 0.8 1-0.90; 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 (fig. 5). Clypeus rather long, broadly convex in both dimensions, middle subsiding evenly to sides; free margin broadly arcuate except for slight median



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19781 Kugler - Pogonomyrmex mayri 177
flattening or ernargination, 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 Table 1. Measurements and indices of Pogonomyrmex mayri females and workers. Data for the first female specimen are listed first, followed by those of the second. Worker data are ranges from 6 individuals selected to include the largest and smallest available from 7 collections. Measurements are expressed in millimeters; indices in percentages, and both follow the standard definitions (see Brown, 1953: 11-14; 1975: 3-4). Head width was measured just behind the eyes. Postpetiolar and gaster measurements were taken separately, and from dorsal view. Measurements
TL
HL
HW
ML
Eye L
Scape L
WL
Petiole L
Petiole W
Postpetiole L
Postpetiole W
Gaster L
Gaster W
Fore femur L
Fore femur W
Hind femur L
Hind femur W
Indices
CI
MI
s I
Scape W/ L
Fore femur W/ L
Hind femur W/L
Petiole W/ L
Postpetiole W/ L
Gaster W/ L
Queens
8.21, 8.49
1.57, 1.58
1.45, 1.52
0.25, 0.27
0.25, 0.25
1.12, 1.20
2.02, 2.00
0.90, 0.90
0.72, 0.68
0.94, 0.94
1.25, 1.20
2.53, 2.80
2.18, 2.14
1.48, 1.50
0.27, 0.27
1.64, 1.65
0.27, 0.26
Workers
7.85-9.04
2.00-2.24
1.73-1.96
0.26-0.35
0.26-0.30
1.67-1.82
2.20-2.54
0.90-1 .OO
0.36-0.43
0.68-0.80
0.59-0.70
1.80-2.24
1.38-1.67
2.00-2.20
0.30-0.35
2.32-2.62
0.30-0.34




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178 Psyche [June-September
second and third flagellar segments. Scape and flagellurn fairly densely covered with short erect hairs; segments 2-12 of flagellurn also very densely endowed with fine appressed pilosity. Trunk uniquely shaped and proportioned, as if the propodeurn has grown forward, compressing the rnesoscuturn and pronoturn, and rotating the neck and head to a more ventral position (fig. 5). Pronoturn very constricted rnesad. Mesonoturn very short (rneso- scutal 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 scutellurn and rnetanoturn raised into a prominent subcircular bulge. Propodeurn elongate (propodeal L/ WL 49-52%),1 dorsal face curving insensibly into declivous face; unarmed. Petiole long, cylindrical, nodeless. Legs long and slender (hind femur L/ WL 834%); front coxae long, compressed front to back (fig. 5). 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-rn) connected the Rs and M veins, creating a second cubital cell. That cross vein joined the Rs well proxirnad 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-rn cross vein. Wings of different venation commonly appear on the same individual.
Hypopygiurn 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. Mesoscutal and propodeal lengths measured from lateral view by taking their maximum length along lines parallel with Weber's length.



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19781 Kugler - Pogonomyrmex mayri 179
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 pronoturn longi- tudinally striate. Striation on postpetiole gives way to purely punctate sculpture in caudal half. Gaster, first and second anten- norneres, and legs smooth and shining, except for weakly striate fore coxae.
Pogonomyrmex mayri clearly belongs to the genus Pogono- myrmex as presently constituted; and is most closely related to members of the subgenus Ephebomyrmex. It is most like Ephebo- myrmex in 15 of the 22 characteristics used by Cole (1968) to distinguish males and workers of the subgenera Ephebomyrmex and Pogonomyrmex, the sting apparatus most resembles that of the Ephebomyrmex species I have examined (Kugler, 1978), and some of its most unusual characters, such as the elongate head of the male, the Y-shaped frontal triangle of the queen and worker, and the circumocular groove, may be seen as the extreme development of characteristics of Ephebomyrmex species. Nevertheless, it is remarkably different from any known Pogonomyrmex, with a number of novel characters, and consequently has been placed in its own subgenus (Forelomyrmex Wheeler) since its description. The following shows how other Pogonomyrmex species compare with mayri's most distinctive features.2
The clypeus in most Pogonomyrmex has a concave leading edge except in angustus, darlingtoni, odoratus, schmitti and townsendi (all Ephebomyrmex), none of which has a median tooth. The frontal triangle is usually broadly triangulate, but is somewhat elongate, laterally compressed, and except for a median carina, depressed except where indicated, based on the
MCZ collection containing 51 of the
estimated 67 presently standing species, subspecies and varieties of the subgenera Ephebomyrmex and Pogonomyrmex.




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180 Psyche [June-September
below the level of the clypeus only in darlingtoni, saucius and schmitti. In none of these, however, is the front so narrow as in mayri, nor is it at all Y-shaped. The back of the head in full dorsal view is broadly and shallowly concave in most Ephebomyrmex species, but is only excavated to such a degree that it has definite occipital lobes in the majors of some subgenus Pogonomyrmex species, e.g., badius. The cephalic index approaches that of mayri only in cunicularius (84), an undetermined species near cunicularius3 (84,87), odoratus (85-87), and angustus (86-89). Only in the latter is the occiput at all concave. In some species the sculpture is flattened at the edge of the eye, but only in darlingtoni does it become at all impressed, and then it is shallow, only weakly defined, and limited to the dorsal half of the eye. All species exarnined have much larger eyes, relative to the size of the head, than mayri. The petiolar node in most Pogonomyrmex species is well rounded on top, sides and apex, and has a distinct posterior peduncle. A few species have a broad subacute to acute apex, but only in the sp. near cunicularius does the node even superficially resemble that of mayri. On closer examination, it also is quite distinct. Sculpture in the subgenus Ephebomyrmex tends to be "coarsely rugo-reticulate" (Cole 1968: 35), but no species exarnined has the overlying broken, undulate pattern of mayri.
Ergatogyny has occasionally been reported in Pogonomyrmex, but most specimens are only occasional aberrations in species with normal queens, e.g., comanche, maricopa, subnitidus, californicus (Cole 1968: 175), and pima (MCZ). Only one female has been reported for cunicularius, and it is ergatoid (Santschi, 193 l), but the description indicates nothing more remarkable about it than a more or less distinct scutellurn. Ergatogyny seems to be the rule in laticeps. Kusnezov (195 1 : 273-275) describes the range of ergatoid forms, but makes no mention of enlarged waists or gasters, or of reduced heads. Those characters are evidently unique to mayri. The bizarre form of the P. mayri male is also apparently unequalled in this genus (Cole, 1968; Creighton, 1952; Gallardo, 1932; Kusnezov, 1949, 195 1). Some males of Aphaenogaster species have elongate heads constricted behind. In the other Pogonomyrmex Two specimens collected by W. L. Brown in Argentina: Catarnarca, Cat. (airport), 4 Feb. 1967; Prov. Tucurnan, Krn 1333, Rte. 9, N. of Tapia, 25 Jan. 1967, bosque chaquefio.




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19781 Kugler - Pogonomyrmex mayri 18 1
species I was able to examine directly, the head is at best only slightly longer than wide in some species (CI range of 4 Ephebo- myrmex species 89-97). The mesoscutum is long (~nesoscutal L/ WL 33-50%), propodeurn short (propodeal L/ WL 26-37%) and the petiole has a distinct node. The legs are shorter than in mayri (hind femur L/ WL 61-76%), and the front wing usually has a r-rn crossvein that joins the Rs at or distal to the end of the first cubital cell (see Cole, 1968: 25-26, plate 1 fig. 1). If the r-rn vein is absent, the first cuboidal cell is open.
Pogonomyrmex mayri may in fact deserve full generic status, but for the present it seems prudent not to create a rnonotypic genus before Pogonomyrmex is completely revised. The most recent revisions (Kusnezov, 1951; Cole, 1968) have been regional in scope and thus inadequate to address the question of whether the sub- genera Pogonomyrmex and Ephebomyrrnex are really two distinct genera. Should such a split occur, mayri would no doubt be placed in the separate genus Forelomyrmex.
I thank Norman F. Johnson for taking the SEM photographs, Janet M. Hahn for helping prepare various stages of the manuscript, W. L. Brown, Jr. for his advice and constant support, and E. 0. Wilson for the loan of specimens from the MCZ. This research was supported by the NSF grant DEB-22427 (W. L. Brown, Jr., principal investigator).
BROWN, W. L.
1953. Revisionary studies in the ant tribe Dacetini. Am. Midi. Nat. 50: 1-137. 1975. Contributions toward a reclassification of the Forrnicidae. V. Ponerinae, tribes Platythyreini, Cerapachyini, Cylindrornyrrnecini, Acanthostichini, and Aenictogitini. Search, Agrculture, Cornell Univ. 5(1): 1-1 16. COLE, A. C.
1968. Pogonomyrmex Harvester Ants, A Study of the Genus in North America. Univ. of Tennessee Press, Knoxville. 222 pp. CREIGHTON, W. S.
1952. Studies on Arizona ants (3), the habits of Pogonomyrmex huachucanus Wheeler and a description of the sexual castes. Psyche 59: 71-81. FOREL, A.
1899.
Biologia Cent.-Am., Insecta, Hyrn. 3 (Forrnicidae), pp. 1-169 + 4 pi.



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182 Psyche [June-September
GALLARDO, A.
1932. Las Horrnigas de la Repbblica Argentina, subfamilia Mirrnicinas, segunda seccion Eurnyrrnicinae, Gknero Pogonomyrmex Mayr. An. Mus. Argent. Hist. Nat. 37: 89-170.
KUGLER, C.
1978. A comparative study of the rnyrrnicine sting apparatus (Hyrnenoptera, Forrnicidae). Stud. Entornol. 20: 413-548. KUSNEZOV, N.
1949.
Pogonomyrmex del grupo Ephebomymex en la fauna de la Patagonia. Acta Zool. Lilloana 8: 291-307.
195 1. El genero Pogonomymex Mayr. (Hyrn,, Forrnicidae). Acta Zool. Lilloana 11: 227-333.
SANTSCHI, F.
193 1.
L'etude des fourrnis de 1'Argentine. An. Soc. Cient. Argent. 112: 273-282.



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