Tranopelta gilva

Longino - Tranopelta gilva are pale, subterranean ants that are never seen foraging on the surface. In the field their general habitus is very similar to the formicine genus Acropyga. Very little is known of the biology. Workers are most often found under rocks in clay soil in lowland rainforest. They may also occur in Winkler and Berlese samples of leaf litter from the forest floor. In Costa Rica I have collected T. gilva at four sites: La Selva Biological Station, 500m elevation on the Barva Transect above La Selva, Hitoy Cerere Biological Reserve, and near Ciudad Neily in the southern Pacific lowlands. At La Selva I once observed a populous colony under the loose bark of a rotten log in primary forest. Knots of workers and uniformly-sized brood were in scattered piles, distributed across at least 2m of the log length. Queens are very large, dramatically larger than the workers. Most queens are collected at lights.

Identification
Propodeum and promesonotum continuous in lateral view, only interrupted by metanotal groove: scape ending before posterior border.

Some morphometric differences exist between the smaller workers (“minors”) and the larger ones (“majors”), such as the cephalic index and the scape index. In the larger workers. the head is more rectangular and the eyes are more faceted, Table 1 compares differences in head width, cephalic index, number of eye facets, number of mandibular teeth, mandibular striation, presence or absence of spines on the subpetiolar process, and locality, among several workers from various locations. Despite the wide variation present in the above characters, no association or correlation among them has been found that allows the separation of more than one species.

Some attributes of queens collected in different localities. The number of teeth is variable, as well as the shape of the median construction. The tooth of the subpetiolar process is also variable, as it may range from absent to conspicuous. Also variable, are the wings of both males and females. In the male student, the two anterior wings are different from one another.

Characters separating each caste of T. gilva from Tranopelta subterranea (the only other species in the genus) are given on the Tranopelta genus page.

Distribution based on Regional Taxon Lists
Neotropical Region: Bolivia, Brazil, Colombia, Costa Rica, Ecuador, Guatemala, Guyana, Honduras, Mexico, Panama, Paraguay, Suriname, Trinidad and Tobago, Venezuela.

Nomenclature

 *  gilva. Tranopelta gilva Mayr, 1866a: 514 (q.m.) VENEZUELA. Wheeler, W.M. 1922e: 6 (w.); Wheeler, G.C. & Wheeler, J. 1955c: 131 (l.). Senior synonym of amblyops (and its junior synonym brunnea), columbica (and its junior synonym albida), heyeri: Fernández, 2003c: 647.
 * amblyops. Monomorium amblyops Emery, 1894c: 148 (w.) BRAZIL. Santschi, 1922d: 251 (q.m.). Combination in Tranopelta: Emery, 1919b: 61. Subspecies of gilva: Wheeler, 1922e: 8. Revived status as species: Santschi, 1922d: 251; Emery, 1922e: 193. Senior synonym of brunnea: Emery, 1919b: 61; Emery, 1922e: 193. Junior synonym of gilva: Fernández, 2003c: 647.
 * heyeri. Monomorium heyeri Forel, 1901g: 389 (w.) BRAZIL. Combination in M. (Martia): Forel, 1908c: 361; in Tranopelta: Forel, 1911d: 396. Junior synonym of gilva: Fernández, 2003c: 647.
 * brunnea. Tranopelta gilva var. brunnea Forel, 1909a: 259 (w.q.m.) PARAGUAY. Junior synonym of amblyops: Emery, 1919b: 61.
 * columbica. Tranopelta heyeri var. columbica Forel, 1912g: 3 (w.) COLOMBIA. Junior synonym of gilva: Emery, 1919b: 61. Revived from synonymy and raised to species: Mann, 1922: 29. Subspecies of heyeri and senior synonym of albida: Emery, 1922e: 193. Junior synonym of gilva: Fernández, 2003c: 647.
 * albida. Tranopelta gilva var. albida Mann, 1916: 446 (w.) BRAZIL. Junior synonym of gilva: Emery, 1919b: 61; of columbica: Emery, 1922e: 193.

Fernández (2003):

Some morphometric differences exist between the smaller workers (“minors”) and the larger ones (“majors”), such as the cephalic index and the scape index. In the larger workers. the head is more rectangular and the eyes are more faceted, Table 1 compares differences in head width, cephalic index, number of eye facets, number of mandibular teeth, mandibular striation, presence or absence of spines on the subpetiolar process, and locality, among several workers from various locations. Despite the wide variation present in the above characters, no association or correlation among them has been found that allows the separation of more than one species.

Some attributes of queens collected in different localities: The number of teeth is variable, as well as the shape of the median construction. The tooth of the subpetiolar process is also variable, as it may range from absent to conspicuous. Also variable, are the wings of both males and females. In the male studied, the two anterior wings are different from one another.

Description
Fernández (2003):

Worker
(n=4) : HW 0.46-1.03 HL 0.50-1.20 SL 0.32-0.54 EL 0.038-0.099 WL 0.53-1.20 PL 0.20 -0.38 PPL 0.15-0.28 GL 0.63-1.20 TL 2.06-4.37 CI 88-92 SI 52-68.

Feebly polymorphic. Head as long as broad (in minors) or longer than broad (in majors). Posterior border of head concave: lateral margins of head slightly concave to nearly straight in majors. Mandibles with four stout teeth, the apical and subapical teeth larger in majors, sometimes five teeth in minors. Mandibles smooth and shining will longitudinal striae. Anterior margin of clypeus sinuous medially concave. Clypeus never carinate; median apical seta absent. Frontal lobes short. Antennal scrobes absent. Eyes minute (with 3-4 facets) to moderate (around 12 facets) in size. Scape short, ending distantly from vertexal border, shorter in majors. In side view, promesonotum and propodeum continuous. Promesonotal suture impressed laterally. Metanotal groove clearly impressed in the dorsum. Propodeum gently rounded, without spines. In dorsal view, mesosoma constricted towards metanotal constriction. Propodea spiracle large, circular to ovoid to elliptical. Bulla of metapleural gland big and bulging. Inferior propodeal plates sometimes connected above the foramen by a faint carinae. Petiole pedunculated, node distinct. Subpetiolar process varies from a faint projection to a conspicuous spine. Petiole ventrally with a median carina posteriorly bifurcated as a “Y.” Ventral petiolar carinae variable in side view, forming one to two spines or angles, sometimes connected by translucent lamella of various development. Postpetiole with distinct anteroventral process, posterior process small or absent. Postpetiole narrowly or broadly attached to the gaster. Gaster sometimes white, translucent and soft. Body smooth, and shining with fine sculpture in the sides of the mesosoma and venter of petiole and postpetiole. Short pilosity of whitish color, erect and sparse on the body dorsum. Body light brown to yellowish, sometimes partially to completely white.

Queen
(n= 1): HW 1.70 HL 1.50 SL 0.90 EL 0.57 WL 3.45 PL 0.80 PPL 0.70 GL 4.5 AA 11.75 TL 11.41 CI 113 SI 53.

Head broader than longer. Posterior margin of head in frontal view convex. Sides convex: eyes at midpoint of head. Scapes short, ending at about 2/3 of the head length from posterior margin. Mandibles with five to six teeth, apical tooth largest. Mandibles slightly to well striated. Mesosoma modified as in myrmicine queens. Promesonotum dorsally with impressed longitudinal central line and two short lateral lines. Front wing as in figure 2H. Propodeal spiracles large, varying from circular to ovoid, sometimes medially constricted. Subpetiolar process variable; anterior spine absent, short or well developed; median carinae feebly impressed to well developed. Postpetiole broadly attached to gaster. Body with fine and densely punctate all over. Pubescence all over the body, especially on head and gaster. Pilosity erect and sparse, yellow brown in color.

Male
(n=1): HW (including eyes) 1.22 HL 1.00 SL 0.33 EL 0.55 WL 2.25 PL 0.48 GL 1.5 TL 5.9 CI 123 SI 27.

Head approximately as broad as long. Mandibles short, not touching when closed. Mandibles with 3 teeth, apical tooth bigger and separated from other two. Clypeus medially concave. Front wing as in figure. Propodeal spiracle circular. Sculpture and pubescence as in female. Long and curved hair on ocellar triangle and clypeus.