Formicidae, Hymenoptera, Insecta, Arthropoda, Animalia
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Image catalog, worker and queen, montage and sem images (click here).
Range
Mexico to Argentina.
Identification
Crematogaster montezumia is distinctive in having a somewhat inflated propodeum, with propodeal spines reduced to short denticles. Only one other species in Costa Rica, raptor, has greatly reduced propodeal spines. Crematogaster raptor has a shiny face, in contrast to montezumia's punctate face.
Description of worker (Costa Rica)
Color dark red brown to black.
Mandibles smooth and shiny, becoming striate near base; clypeus emarginate anteriorly, convex, shiny; face punctate over much of surface, with variably developed anteromedian strip on face smooth and shiny; scapes with a combination of erect and subdecumbent setae, setae abundant, as long as width of scape or greater; terminal three segments of antenna gradually lengthening and becoming increasingly densely pubescent, terminal two segments the largest and most conspicuous, so that antennal club appears two-segmented; face with abundant erect amber setae; in full face view abundant setae projecting from posterior margin and sides of head posterior to eye, absent anterior to eye.
In lateral view, pronotum short but strongly convex, mesonotum differentiated from pronotum, somewhat projecting and forming elevated anterior boss; propodeal suture deeply impressed, in some cases obscured in lateral view by small lateral carinulae that bridge suture; mesonotum and dorsal face of propodeum in about the same plane; dorsal and posterior faces of propodeum distinct; propodeum strongly swollen, large relative to promesonotum; propodeal spines very short, acute, sharp; side of pronotum and katepisternum with faint microareolate microsculpture, sublucid; side of propodeum smooth and shining; promesonotal dorsum and dorsal face of propodeum punctate, overlain with clathrate rugae; posterior face of propodeum smooth and shiny; promesonotum and dorsal face of propodeum with abundant amber to whitish erect setae of variable lengths, no setae on posterior face of propodeum; legs with relatively sparse, short, fully decumbent setae.
Petiole in side view triangular, with faint microareolate sculpture; anteroventral tooth completely absent; dorsal face rectangular, longer than wide, smooth and shiny on anterior two thirds, faintly microaerolate on posterior third, with row of setae across posterior margin; postpetiole with blunt ventral tooth, postpetiole in dorsal view subquadrate, wider than long, posterior margin emarginate, with longitudinal median sulcus, and four pairs erect setae; fourth abdominal tergite with faint microareolate sculpture; fourth abdominal tergite with abundant erect setae.
Measurements:
HL 0.621, 0.563, 0.621; HW 0.681, 0.608, 0.670; HC 0.613, 0.566, 0.601; SL 0.593, 0.522, 0.570; EL 0.175, 0.146, 0.189; A11L 0.264; A11W 0.127; A10L 0.125; A10W 0.097; A09L 0.062; A09W 0.070; A08L 0.055; A08W 0.065; WL 0.728, 0.626, 0.708; SPL 0.055, 0.048, 0.107; PTH 0.181, 0.147, 0.162; PTL 0.269, 0.208, 0.250; PTW 0.184, 0.155, 0.187; PPL 0.177, 0.142, 0.183; PPW 0.235, 0.206, 0.229; CI 110, 108, 108; OI 28, 26, 30; SI 95, 93, 92; PTHI 67, 71, 65; PTWI 68, 75, 75; PPI 133, 145, 125; SPI 8, 8, 15; ACI 1.58.
Description of Queen (Costa Rica)
In lateral profile dorsal face of propodeum sloping obliquely from postscutellum, such that most of propodeum is posterior to scutellum (in contrast to normal queens, in which dorsal face of propodeum drops steeply from postscutellum and much of propodeum appears ventral to scutellum and postscutellum); entire body (head, mesosoma, petiole, postpetiole, fourth abdominal tergite, appendages) polished, very smooth and shiny; mandible smooth and shiny, apical tooth of masticatory margin long and narrowly acute, much longer than other teeth; anterior margin of clypeus emarginate; clypeus with a broad anteromedian concavity; antennal club three-segmented; scapes with combination of long decumbent setae and long erect setae; face, pronotal dorsum, and anterior mesonotum with abundant erect white setae, sparser erect setae on remainder of mesosomal dorsum, posterior petiole, postpetiole, and fourth abdominal tergite; propodeal spines present, narrowly acute; femora with sparse long appressed pilosity; tibiae with abundant suberect setae; petiole similar to worker, with no anteroventral tooth, dorsal face subrectangular, slightly wider anteriorly than posteriorly, with anterolateral humeri somewhat produced as gibbosities and anteromedian area concave.
Natural History
Crematogaster montezumia inhabits wet to dry forest habitats throughout the mainland Neotropics. In Costa Rica it occurs in very low density, but abundant museum collections and my own collecting in the Santa Marta area of Colombia suggest a higher density in some South American localities. Most of my observations of the species have been from brushy second growth vegetation or forest edges.
Nests are in small to large carton nests that the workers construct and vigorously defend (Emery 1890, Forel 1899, Forel 1901b, Luederwaldt 1926). The nests are in dry, exposed areas and do not contain epiphytes. Luederwaldt (1926) includes photographs of three nests. Nests I have observed have been on relatively thin branches. One I observed in Corcovado National Park in Costa Rica was on a shrub overhanging a river. The nest was 15-20cm long, 10cm wide, of black carton, and it contained workers, brood and many alate queens. During a field trip to the Santa Marta area of Colombia I discovered several nests. One nest was in dry forest near a beach margin. The nest was in a knot in a small tree out in an open field. When I disturbed the nest the workers responded by quickly swarming out and running over the knot with prominent gaster-flagging. The nest contained workers, brood, and a single queen.
Another nest was in a scrubby second growth area with pastures. A carton nest was partly covered by a dead Cecropia leaf draped over a 13mm diameter live stem of Guazuma (Sterculiaceae). Under the nest was a dense accumulation of scale insects, but no scales were exposed on the plant stems or leaves. The nest was filled with workers, brood, and one colony queen. Workers were spread over the surrounding vegetation, often moving in files, and there were small satellite nests scattered around the main nest.
A third nest was in dry forest, and they were nesting in a peculiar way. They were on a small shrub that was possibly Pisonia (Nyctaginaceae). Stems had opposite leaves with a pair of sharp recurved spines at each node, often with opposite short leafy branches at each node. On one branch, each node for 5-10 nodes had a circular hole at the base of the side branch, entering a tiny chamber only a few millimeters deep. The chambers were all occupied by workers, and one chamber was slightly larger than the others and contained workers, a small amount of brood, and a queen. A search in surrounding holes and dead stems and branches yielded no more, suggesting the colony was rather small, perhaps limited to the small number I observed.
At La Selva Biological Station nests of montezumia have never been found, but an alate queen was obtained in a canopy fogging sample. The only other Atlantic slope collection I have seen was a dealate queen I found in a small nest of C. curvispinosa. A small grass stalk contained the montezumia queen and a small number of workers of curvispinosa.
The queens are shiny and with falcate mandibles, a combination of characters often associated with social parasitism. The observation of the lone queen together with curvispinosa workers is suggestive of a parasitic lifestyle, in which colonies of host species are usurped to provide a worker force that helps establish the colony of the parasitic species. The observation of what appeared to be an incipient colony in Colombia showed no evidence of social parasitism, although it is possible that the queen had started with a heterospecific host colony and it had been completely extirpated and replaced by the montezumia workers. Alternatively, the tiny queens could be an adaptation for nest founding in extremely small spaces, such as the small cavities in the Pisonia stem.
Synonyms
C. montezumia F. Smith 1858. Mexico to Argentina.
= sulcata Mayr 1870. Colombia.
= ramulinida Forel 1899. Colombia.
= functa Forel 1911. Brazil (Sao Paulo).
= cristulata Santschi 1925. Brazil (Santa Catarina).
= proletaria Santschi 1933. Argentina.
Page author:
John T. Longino, The Evergreen State College, Olympia WA 98505 USA. longinoj@evergreen.edu
Date of this version: 4 March 2003.
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