Proceratium croceum

This is one of the more commonly collected species in the genus. They live in rotten logs and stumps in shady areas. Colonies are sometimes found beneath the bark of decaying pine logs. Cole (1940) found a colony of about 30 workers in a small nest in firm wood near the middle of a rotten log; he points out how easy it would be to miss the nests of this species unless one carefully dissects entire logs. Van Pelt (1958) found several nests in rotten pine logs. Haskins (1930) fed a captive colony on larvae and pupae of other ants, but the Proceratium larvae died before becoming full grown. It is probable, considering the diet of other species (Brown I958a, 1980), that the normal diet is arthropod eggs.

Identification
Proceratium croceum is the largest species of the silaceum clade known from the United States. Resembling Proceratium silaceum but differing from it in the worker, gyne and male by the thicker petiole, by stronger sculpture and by the larger size: worker TL > 3.7 mm, gyne TL > 5.1 mm, male TL > 4.0 mm instead of worker TL < 3.5 mm, gyne TL < 4.1 mm, male TL < 3.3 mm. (Baroni Urbani and de Andrade 2003)

Workers and queens have a high, angulate petiole (in lateral view), distinguishing them from Proceratium pergandei, Proceratium creek and Proceratium chickasaw. The length of the worker is greater (about 3mm) than that of Proceratium silaceum (seldom more than 2.5 mm), and the mesosoma of the worker has (in lateral view) a slight concavity where the mesonotum is joined to the metanotum, this area is flat in P. silaceum.

Distribution
United States: Illinois, Oklahoma, Arkansas, Tennessee, Mississippi, Alabama, Louisiana, Virginia, North Carolina, South Carolina, Texas, Georgia, Florida. Other state records from the literature but not verified by ourselves are not included. Most of them, however, appear perfectly plausible. (Baroni Urbani and de Andrade 2003)

In Florida P. croceum is known from a small number of sites in the northern quarter of the state, south into Levy County.

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



Nomenclature

 *  croceum. Ponera crocea Roger, 1860: 288 (q.) U.S.A. Emery, 1895c: 265 (w.); Smith, M.R. 1930a: 390 (m.); Wheeler, G.C. & Wheeler, J. 1952a: 135 (l.). Combination in Sysphingta: Mayr, 1866a: 501; in Proceratium: Mayr, 1886d: 437. See also: Baroni Urbani & De Andrade, 2003b: 397.

Worker
Baroni Urbani and de Andrade (2003) - Head slightly longer than broad or almost as long as broad and with subparallel sides. Vertex in full face view weakly convex. Clypeus reduced and as long as the antennal sockets. Anterior border of the clypeus truncate. Frontal carinae far from each other, slightly covering the antennal insertions. Lateral expansions of the frontal carinae broad, weakly raised, diverging on the two anterior fourths, converging on the third fourth, subparallel and carinate only on the last fourth. Frontal area gently concave on the anterior three fourths and with a median, longitudinal carina and prolonging posteriorly. Head anterolaterally with a longitudinal carina. Genal carinae marked, each carina corresponding to the external border of a deep sulcus. Eyes represented by a dark dot below the integument, small and placed on the middle of the head sides. First funicular joint slightly longer than broad. Funicular joints 2-10 broader than long. Last funicular joint as long as the sum of joints 8- 10, or slightly shorter than the sum of joints 7-10, or as long as their sum. Scapes short of the vertexal margin and gently broadened apically. Masticatory margin of the mandibles with 11-13 denticles before the pointed apical tooth. Palp formula 2,2.

Mesosoma in side view convex on the two anterior thirds, sloping on the posterior third, and about as long as the maximum head length (mandibles included). Pronotal and propodeal sutures superficially impressed. Basal face of the propodeum declivous posteriorly. Area between the basal and declivous Faces of the propodeum gently concave, dorsally variably carinate and laterally with a broad tooth. Declivous face of the propodeum gently sloping posteriorly. Sides of the declivous face of the propodeum carinate. Propodeal spiracle round and above mid height in lateral view.

Petiole rectangular and broad. Anterior border of the petiole straight and anterolaterally carinate, with the posterodorsal border of the node superficially carinate and medially angulate in dorsal view. Ventral process of the petiole large, lamelliform, oblique anteriorly and pointed posteriorly. Postpetiole in dorsal view with the sides diverging on the anterior half and gently convex on the posterior half. Postpetiolar sternite anteromedially with a marked subtriangular projection, gently convex posteriorly in side view. Constriction between postpetiole and gaster impressed. Gastral tergite I about ½ longer than the postpetiole and convex on the curvature. Remaining gastral tergites and sternites curved ventrally.

Legs moderately elongate. All tibiae with a pectinate spur. Spurs of fore legs without basal spine. Fore basitarsi longer than the mid ones. Hind basitarsi about 1/4 or 1/5 shorter than hind tibiae. Second tarsomere of hind leg shorter than pretarsus. Pretarsal claws simple. Arolia absent.

Sculpture. Head and rnesosoma minutely punctate, reticulorugose, the reticulation larger on the sides of the head, the rugosities thicker and slightly longitudinal on the head sides and slightly concentric on the pronotum and on the mesonotum. Petiole and postpetiole reticulate, the reticulation deep and foveae-like. First gastral tergite smooth and with minute piligerous punctures. Legs punctate.

Body covered by hairs of three types: (1) short, dense, suberect or subdecumbent, erect and sparse on the f'uriicular joints; (2) longer than type (1), erect, absent on the antennae; (3) shorter than hair type (1), dense and decumbent on the funicular joints. In addition the funicular joints bear whitish, thick, appressed, sparse hairs, and the scapes with sparse hairs similar to type (2) but slightly shorter.

Colour. Ferrugineous-brown with lighter antennae and legs.

Measurements in mm and Indices: TL 3.86-5.03; HL 0.84-1.04; HW 0.83-1.02; EL 0.04-0.06; SL 0.60-0.71; WL 1.08-1.36; PeL 0.28-0.39; PeW 0.38-0.51; HFeL 0.68-0.86; HTiL 0.55-0.69; HBaL 0.41-0.55; LS4 0.44-0.64; LT4 0.82-1.12; CI 98.0-98.8; SI 68.2-1.4; IGR 0.54-0.57.

Queen
Baroni Urbani and de Andrade (2003) - Differing from the worker in the following details: eyes large, slightly more than 1/4 of the head length, composed by many facets and with ocular pilosity. Ocelli well developed.

Mesosoma robust and gently convex in side view. Parapsidal furrows marked. Scutellum with the sides converging posteriorly and with the posterior border round. Dorsum of the mesonotum and scutellum with a longitudinal carina thicker posteriorly. Metanotum with a large lamellaceous tooth. Basal face of the propodeum flat.

Fore wings of our type 4, hind wings of our type 3 as defined in the description of the genus.

Sculpture. Mesosoma variably reticulorugose, sometimes the rugulae absent.

Measurements in mm and Indices: TL 5.23-5.43; HL 1.04-1.08; HW 1.00-1.02; EL 0.28-0.30; SL 0.71-0.73; WL 1.52-1.60; PeL 0.39; PeW 0.56; HFeL 0.94-0.97; HTiL 0.71-0.75; HBaL 0.60-0.62; LS4 0.63-0.72; LT4 1.16-1.28; CI 94.4-96.1; SI 67.6-69.2; IGR 0.53-0.56.

Male
Baroni Urbani and de Andrade (2003) - Head slightly broader than long. Vertex in full face view strongly convex. Vertexal margin carinate. Clypeus reduced, truncate and as long as or slightly longer than the antennal sockets. Frontal carinae thin, low, parallel. Frontal area convex anteriorly and concave posteriorly. Ocelli large. Compound eyes large and occupying mostly the anterior part of the head sides. Scapes almost reaching the anterior ocellus. First funicular joint about 1/2 shorter than the second joint. Joints 2-12 much longer than broad. Last funicular joint about as long as the sum of joints 10-11. Mandibles edentate and only with a pointed apical tooth. Palp formula 5,2.

Mesosoma robust and convex in profile. Pronotum and anterior third of mesonotum almost perpendicular to the posterior two thirds of the mesonotum. Parapsidal furrows marked. Scutellum slightly higher than the mesonotum; posterior border of scutellum round. Basal face of the propodeum flat and with an incision prolonging to the anterior part of the declivous face medially. Sides between basal and declivous faces of the propodeum angulate. Declivous face of propodeum flat. Metanotum with a median, broad, spiniform tooth. Lower part of the propodeal lobes truncate and upper part round and partially lamelliform. Propodeal spiracles small.

Petiole in side view with truncate or declivous anterior face, the node subrectangular. Anterior border of the petiole laterally carinate. Subpetiolar process as in the worker and gyne but less developed. Postpetiole anteriorly slightly broader than the petiole; postpetiolar sides gently convex. Anterior border of the postpetiolar sternite with a superficial triangular "lip". Gastral tergite I convex in side view. Gastral sternite I large. Remaining gastral tergites and sternites slightly curved ventrally.

Legs as in the worker but more elongate. Hind basitarsi slightly shorter than hind tibiae.

Fore wings of our type 4, hind wings of our type 3 as defined in the description of the genus.

Sculpture. Head, mesosoma and petiole reticulorugose, this sculpture more marked and larger on the propodeum. Postpetiole and gaster smooth and with minute piligerous punctures. Legs superficially smooth and minutely punctate.

Pilosity as in the worker but with the hairs of type (2) slightly longer on the gaster.

Colour. Head, dorsum of the mesosoma and of the petiole dark brown-black with the remaining body parts lighter.

Measurements in mm and Indices: TL 4.14-4.60; HL 0.71-0.78; HW 0.74-0.80; EL 0.35-0.39; SL 0.38-0.40; WL 1.36.1.54; PeL 0.29-0.33; PeW 0.38-0.43; HFeL 0.83-0.91; HTiL 0.59-0.69; HBaL 0.57-0.64; LS4 0.49-0.64; LT4 0.87-1.12; CI 102.6-104.2; SI 51.3-53.5; IGR 0.56-0.61.

Type Material
Type locality: Carolina, USA. Type material: holotype gyne without postpetiole and gaster labelled "Carolina, TYPE, crocea Roger, Proceratium croceum Rog, Zool. Mus. Berlin", in ZMBC, examined.