Cyphomyrmex flavidus

Collected in Mexico nesting under rocks.

Identification
Wheeler (1907) - at first sight closely resembles Cyphomyrmex wheeleri. It may be distinguished, however, by the absence of teeth on the petiole, the much broader and more truncated ear-like corners of the head, longer antennal scapes and much blunter ridges and projections on the thorax. C. flavidus is thus intermediate in several respects between wheeleri and Cyphomyrmex rimosus, but is undoubtedly a distinct species.

Distribution based on Regional Taxon Lists
Nearctic Region: United States. Neotropical Region: Mexico.

Biology
Kempf (1966) reported the following about the synonymized dentatus:

According to Wheeler (1901: 200-1), who first collected this species on December 26 (year not given), the species is "not uncommon along the barrancas where it nests under stones, forming irregular chambers about the roots of the grasses. There are sometimes two queens in a nest. The older and darker queens and workers have the head and thorax covered with a bluish bloom. C. rimosus (Wheeler obviously refers to the present form which he considered as a mere race of rimosus! W. W. K.) is said not to cultivate mushroom gardens, but this is scarcely correct. They certainly collect caterpillar excrement and on this they grow a peculiar fungus which is not in the form of a white mycelium, like that cultivated by some other species of Cyphomyrmex (C. wheeleri Forel, for example) but consisting of clusters of small orange yellow, spherical or pyriform nodules about 5 mill. (= 0.5 mm?) in diameter. The exhausted masses of caterpillar excreta are piled on the refuse heap in a distant corner of the nest. The eggs of C. rimosus (again the present form is meant! W. W. K.) are very broad and short, almost spherical".

Dr. Skwarra (1934: 131) rediscovered the same species at Cuernavaca, finding two earth nests, one of them in the loosely heaped up refuse of Atta nests. She surmises that dentatus possibly uses this material as substrate for its own fungus.

Nomenclature

 *  flavidus. Cyphomyrmex flavidus Pergande, 1896: 895 (w.) MEXICO. See also: Wheeler, W.M. 1907c: 726; Kempf, 1966: 172. Senior synonym of dentatus: Snelling, R.R. & Longino, 1992: 485.
 * dentatus. Cyphomyrmex rimosus r. dentatus Forel, 1901c: 124 (w.) MEXICO. Wheeler, W.M. 1907c: 723 (q.). Raised to species: Kempf, 1966: 184. Junior synonym of flavidus: Snelling, R.R. & Longino, 1992: 485.

Worker
Wheeler (1907) - Length: 2.2-2.8 mm.

Head, without the mandibles, longer than broad, broader behind than in front, with obtusely excised posterior border and prominent posterior corners. Eyes convex, at the middle of the head. Mandibles small and acute, with oblique, apparently 5-toothed blades. Clypeus long and rather flat, with a minute median excision in its thin anterior border. Frontal area triangular. Lobes of frontal carina very large, horizontal, half as long as the head and extending out laterally a little beyond the borders of the head. Posteriorly each of these lobes has a deep subtriangular depression in its surface. The ridges of the frontal carina diverge backward to the posterior corners where they pass over into the postorbital carina, not through a rounded arc but rectangularly, so that the termination of the antennal groove is broad and truncated. There is a ridge on each side of the inferior occipital portion of the head and a pair of projections on the vertex, which are continued laterally along the occipital border as a pair of blunt ridges to the posterior corners. Antennal scapes enlarged towards the tips, which extend a little beyond the posterior corners; joints 2-7 of the funiculus a little broader than long. Thorax robust; pronotum with a pair of acute inferior teeth, which are directed forward, and a blunt protuberance on each side above', Mesonotum in the form of an elevated, elliptical and slightly concave disc, bordered with a low ridge which is interrupted in the middle behind and in the middle on each side. This ridge bears a pair of rounded swellings just in front of its lateral interruptions. Mesoepinotal constriction deep and narrow. Epinotum with a pair of swellings at its base; declivity sloping, longer than the base; spines reduced to a pair of laterally compressed and rather acute teeth which are as long as they are broad at the base. Petiole and post petiole resembling each other in shape; the former twice as broad as long, broader behind where its sides are produced as a pair of blunt angles; it is flattened above, without spines or teeth and with a small semicircular impression in the middle of its posterior border. Postpetiole broader than the petiole, more than twice as broad as long, rounded in front, with a median groove, broadening behind; posterior margin with three semicircular impressions of which the median is the largest. Gaster longer than broad, suboblong, with straight, feebly marginate sides, rounded anterior and posterior borders, and a short median groove at the base of the first segment. Hind femora curved, with an angular, compressed projection near the base on the flexor side. Opaque throughout, very finely and densely punctate-granular.

Hairs minute, appressed, slightly dilated, glistening white, rather sparse and indistinct. Pubescence fine, whitish, confined to the antennal funiculi.

Ferruginous yellow; clypeus, frontal lobes, front and middle of vertex more or less brownish; mandibular teeth black.

Queen
Wheeler (1907) describing the synonymized dentatus:

Two dealated females of dentatus in my collection measure 2.4 mm. in length, and have prominent but blunt and upturned prothoracic spines and strong laterally compressed epinotal teeth; the epinotal declivity is very concave, the postero-lateral cones of the postpetiole are more prominent and the median dorsal region of the same segment is more concave than in the worker. The head and thorax are much rougher than in the females of the typical rimosus and the gaster is more strongly tubercular, with a short but deep median depression at the base of the first segment. The body is dark brown, the upper surface of the head and thorax blackish and covered with a bluish bloom.

Type Material
Kempf (1966) - Workers collected by Eisen and Vaslit at Tepic and Santiago Ixcuintla in Nayarit State, Mexico; presumably deposited in the U.S. National Museum. No specimens seen.