Proceratium chickasaw

Prior to its description in 2003, this species was typically identified as Proceratium pergandei.

Identification
A member of the pergandei clade. Proceratium chickasaw is extremely similar to Proceratium pergandei. Differs from pergandei by having the postpetiole superficially granulate instead of densely granulate, the rearward extension of the second gastral segment longer and narrower, in lateral view as long as the first tergite, and the second gastral segment covered with slender hairs that stand up from the surface of the segment and bend back at the ends, rather than being covered with uniformly curved decumbent hairs as in P. pergandei. (Modified from Baroni Urbani and de Andrade 2003)

Distribution
Known from Tennessee, Alabama, Mississippi and Florida.

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

Biology
The Florida specimens were collected from leaf litter in deep ravines in the Apalachicola River drainage. These ravines are refuges for certain plants and animals of the southern Appalachian Mountains.

Nomenclature

 *  chickasaw. Proceratium chickasaw De Andrade, in Baroni Urbani & De Andrade, 2003b: 235, figs. 98, 99 (w.) U.S.A.

Worker
Head longer than broad, its sides subparallel in the two anterior thirds and gently converging in the posterior third. Anteromedian part of the clypeus rectangular and strongly protruding anteriorly, dorsally with a variably marked inverted Y-shaped carina. Frontal carinae diverging posteriorly, slightly raised and not very close each other. Lateral expansions of the frontal carinae narrow. Genal carina absent. Gular area not impressed. Eyes small, composed by a minute, flat dark dot below the integument. Eyes placed on the mid line of the head. First funicular joint about 1/5 longer than broad. Funicular joints 2-10 almost as broad as long or slightly broader than long. Last funicular joint about as long as the sum of joints 8-10. Scapes much short of the vertexal margin and gently thickening apically. Antennal torulus placed behind the lateral border of the clypeus. Masticatory margin of the mandibles with 4-5 denticles before the pointed apical tooth. Palp formula 4,3.

Mesosoma as long as or slightly shorter than maximum head length (mandibles included). Promesopleural and meso-metapleural sutures impressed ventrally only. Basal and declivous faces of the propodeum separated by a carina sometimes interrupted medially. Declivous face of the propodeum with a relatively broad semitransparent lamella sometimes denticulate on each side between the basal and declivous faces. Propodeal spiracle round and placed above mid height in lateral view.

Petiole convex in profile, with the sides diverging on the anterior fourth and strongly convex posteriorly in dorsal view. Anterior border of the petiole gently concave and not carinate. Ventral process of the petiole lamelliform, triangular and pointed. Postpetiole anteriorly as broad as or only slightly broader than the petiole; its sides diverging, sometimes gently convex posteriorly. Postpetiolar sternite anteromedially with a marked subtriangular projection. Posterior half of the postpetiolar sternite convex. Constriction between postpetiole and first gastral segment impressed. Gastral tergite I strongly projecting on the curvature. Remaining gastral tergites and'sternites curved ventrally and placed on the anterior half ol the first gastral tergite.

Legs slender but not very elongate. All tibiae with a pectinate spur. Spurs of fore legs with basal spine. Fore basitarsi longer than the mid ones. Hind basitarsi about 1/5 shorter than hind tibiae. Second tarsomere of hind leg longer than the pretarsus. Pretarsal claws simple. Pretarsal arolia absent.

Sculpture. Body minutely granulopunctate, the granulation less marked and sparse on the postpetiole and on the legs, absent from the gaster. Gaster shining and with minute piligerous impressions.

Pilosity similar to the one of pergandei but differing in the following: hair type (1) sparser on the gaster and hairs types (1 and 2) longer on the gaster.

Colour light brown.

Measurements in mm and Indices: TL 3.79-4.41; HL 0.82-0.94; HW 0.71-0.82; EL 0.04-0.05; SL 0.54-0.64; WL 1.00-116; PeL 0.32-0.35; PeW 0.32-0.36; HFeL 0.64-0.75; HTiL 0.55-0.66; HBaL 0.43-0.52; LS4 0.25-0.30; LT4 1.00-1.25; CI 85.2 -87.2; SI 65.8-71.6; IGR 0.24-0.26.

Type Material
Holotype worker from Farmer, Polk County, Tennessee, USA, labelled: "Farmer, Polk Co., Tenn., V.25.51, E. O. Wilson, Sysphincta pergandei Em, det. W. L. Brown", in. Paratypes: 3 workers labelled as the holotype, 2 paralype workers in, 1 paratype worker in MCZ.

Etymology
This species is named after the Chickasaw, an Indian tribe from Tennessee.

References based on Global Ant Biodiversity Informatics

 * Baroni Urbani C., and M.L de Andrade. 2003. The ant genus Proceratium in the extant and fossil record (Hymenoptera: Formicidae). Museo Regionale di Scienze Naturali, Monografie 36: 1-480.
 * Forster J.A. 2005. The Ants (hymenoptera: Formicidae) of Alabama. Master of Science, Auburn University. 242 pages.
 * MacGown J. A., J. G. Hill, and R. L. Brown. 2010.  Native and exotic ant in Mississippi state parks.  Proceedings:  Imported Fire Ant Conference, Charleston, South Carolina, March 24-26, 2008: 74-80.
 * MacGown, J.A and J.A. Forster. 2005. A preliminary list of the ants (Hymenoptera: Formicidae) of Alabama, U.S.A. Entomological News 116(2):61-74
 * MacGown. J. 2011. Ants collected during the 25th Annual Cross Expedition at Tims Ford State Park, Franklin County, Tennessee