Cyphomyrmex transversus

Little is known about the biology of this species.

Identification
See the nomenclature section below.

Distribution
Kempf (1966) - Known to occur from northern Brazil to central Argentina. Being more xerophilous than the otherwise omnipresent Cyphomyrmex rimosus, it even occurs in the dry northeastern Brazil as the only representative of the genus.

Distribution based on Regional Taxon Lists
Neotropical Region: Argentina, Brazil, Ecuador, Paraguay.

Biology
Kempf (1966) - From my field experience in Agudos I have come to the conclusion that transversus nests in dryer situations (open fields, parkland) than Cyphomyrmex rimosus which prefers the more humid environment of dense woodlands. The distribution of the former seems to confirm this rule.

Bruch (1923) has studied and pictured the fungus-garden and nest of "pencosensis" in the Argentine. In fact, this ant cultivates a yeast-like fungus on excrements of insects, principally acridid grasshoppers, much as the typical rimosus and its allies.

Nomenclature

 *  transversus. Cyphomyrmex rimosus subsp. transversus Emery, 1894c: 226 (w.q.m.) BRAZIL. Raised to species: Kempf, 1966: 193. Senior synonym of olindanus: Wheeler, W.M. 1907c: 723; Wheeler, W.M. 1925a: 45; of pencosensis: Kempf, 1966: 193.
 * olindanus. Cyphomyrmex rimosus r. olindanus Forel, 1901e: 337 (w.) BRAZIL. Junior synonym of transversus: Wheeler, W.M. 1907c: 723.
 * pencosensis. Cyphomyrmex rimosus var. pencosensis Forel, 1914d: 281 (w.) ARGENTINA. Santschi, 1931e: 278 (q.m.). Subspecies of rimosus: Weber, 1940a: 411 (in key). Junior synonym of transversus: Kempf, 1966: 193.

Kempf (1966) - The chief separatory characters between transversus and rimosus s. l. are given for the female in the diagnosis. The worker differs from Cyphomyrmex rimosus in the feeble and low pair of carinae on vertex; the distinctly dentate antero-inferior corner of pronotum; the low mesonotal ridges, as seen in profile, especially the posterior pair - both pairs encircling the slightly impressed disc much as in peltatus and dentatus; the rather shallow mesoepinotal constriction, appearing as an obtuse angle in profile; the two pairs of tubercles on the posterior corner of the basal face of epinotum; the strikingly transverse pedicelar nodes, principally the petiole; the deeply impressed middorsal groove on postpetiole; the long and hairless antero-median groove on tergum I of gaster; the body hairs which are thickly squamate, especially on head, thorax and gaster. Although due to variation proper to this group some of the aforesaid characters may occasionally fail to reach their full expression - or rimosus in one or the other specimen may imitate one or very few of the characters of transversus - their ensemble will always be sufficient to separate transversus from rimosus.

Worker
Kempf (1966) - Total length 2.7-3.4 mm; head length 0.67-0.83 mm; head width 0.64-0.80 mm; thorax length 0.88-1.09 mm; hind femur length 0.69-0.83 mm. Uniformly yellowish brown to more or less fuscous brown; especially cephalic dorsum and gaster are occasionally more distinctly infuscated. Integument finely and densely punctate-granulate, opaque.

Head (fig 12). Mandibles reticulate-striolate and somewhat shining. Clypeus having the anterior border either straight or slightly concave, bearing on its corners a weak, blunt tooth. Frontal area impressed, without hairs. Frontal lobes semicircular, greatly expanded laterad; frontal carinae a bit sinuous and diverging caudad, attaining the slightly produced occipital corner. Midfrontal tumulus and transverse frontal groove extremely feeble; head disc nearly flat. Paired carinae on vertex blunt, low, extremely weak to vestigial. Preocular carina curving mesad above eye, not joining up with the feeble carina extending from the occipital lobe foreward to the postero-inferior border of eye. The latter with about 9-10 facets across its greatest diameter. Supraocular tubercle usually weak, contained in, and marked as a blunt angle of, the postocular carina. Inferior border of cheeks sharply marginate. Scape in repose surpassing the occipital corner by a distance subequal to its maximum width. Funicular segments II-IX not longer than broad; segment I a bit longer than II and III combined.

Thorax (fig 24). Pronotum dorsally with four tubercles, the median pair smallest; antero-inferior corner with a prominent tooth; sides of dorsal disc feebly marginate in front of the blunt, lateral tubercles. Mesonotum shallowly impressed, flanked by two pairs of low, ridge or welt-like tubercles; both the anterior and the posterior pair often fused to each other forming transverse, semicircular ridges, somehow imitating the condition obtained in peltatus and dentatus. Mesoepinotal constriction usually rather shallow in profile, forming an extremely blunt angle. Basal face of epinotum subquadrate, laterally bluntly marginate, each side bituberculate, the anterior tubercle obtuse, the posterior usually more prominent and tooth-like, situated below the level of basal face on the upper third of the declivous face. Basal third of hind femora gradually incrassate on flexor face, then forming an obtuse angle; the distal two thirds attenuate; posterior border of flexor face sharply marginate or even carinulate especially on bent.

Pedicel (fig 24, 30). Petiolar node strikingly transverse, about thrice as broad as long, lacking a dorsally produced crest and teeth on posterior border; strongly constricted in front of postpetiolar insertion. Postpetiole likewise rather broad, with a usually deeply impressed midlongitudinal groove and a shorter and broader groove posteriorly on each side. Tergum I of gaster with an antero-median groove, at least as long as petiole and hairless; lateral borders of same tergum distinctly marginate.

Body hairs squamate and reclinate, unusually short, thick and conspicuous on head, thoracic dorsum and gaster; narrow, squamate and appressed hairs on scapes and legs.

Queen
Kempf (1966) - Total length 3.5-4.2 mm; head length 0.80-0.93 mm; head width 0.76-0.88 mm; thorax length 1.09-1.33 mm; hind femur length 0.80-1.04 mm. This caste resembles quite closely that of Cyphomyrmex rimosus. The lateral ocelli, not prominent nor placed on raised ridges; the distinctly dentate antero-inferior corner of pronotum; the always well developed and salient epinotal spines; the striking width of the pedicelar segments, even better expressed in this caste than in the worker; the deep longitudinal furrow on the postpetiolar dorsum, distinguish transversus from rimosus. The squamate body hairs are of the same kind as in worker. Wings infuscated, venation as represented by Kusnezov (1949, pl. 1, fig. 15).

Male
Kempf (1966) - There is a scant diagnosis of this caste in Wheeler (1907: 724).

Type Material
Kempf (1966) - Workers and a female, collected by P. Germain at an unidentified locality in Mato Grosso, Brazil, presumably in the Emery collection; not seen. One syntype worker of olindanus Forel received on loan from the MCZ. Types of pencosensis presumably in the Forel collection; not seen.