Proceratium mancum

Identification
A member of the silaceum clade and resembling Proceratium silaceum but differing from it, in the worker and gyne, by the posterior half of the head dorsum less sculptured, by the hairs of type (2) longer and denser over the whole body and by the legs also with longer hairs (worker: mid basitarsi with hairs at least 2/3 of its length instead of at most 1/2 of its length; gyne: mid basitarsi with hairs at least 1/3 of its length instead of shorter than 1/3 of its length).

The silaceum clade is represented by 4 species in the New World. Proceratium mancum is the sole New World species of the silaceum clade occurring in the Neotropics. The other three species, Proceratium croceum, Proceratium silaceum and Proceratium crassicorne are apparently confined to the Nearctic region. mancum can be easily distinguished from croceum, silaceum and crassicorne by the presence of longer body hairs of type (2). This trait is especially visible on the mid and hind basitarsi where they reach at least half of the basitarsal length. (Baroni Urbani and de Andrade 2003)

Distribution
Mexico, Belize, Guatemala, Honduras, Costa Rica and Colombia.

Distribution based on Regional Taxon Lists
Neotropical Region: Belize, Colombia, Costa Rica, Guatemala, Honduras, Mexico.

Nomenclature

 *  mancum. Proceratium mancum Mann, 1922: 6 (w.q.) HONDURAS. Junior synonym of silaceum: Brown, 1974a: 82. Revived from synonymy: Baroni Urbani & De Andrade, 2003b: 430.

Worker
Baroni Urbani and de Andrade (2003) - Head slightly longer than broad with the sides gently diverging posteriorly. Vertex in full face view gently convex. Clypeus reduced and as long as the antennal sockets. Anterior border of the clypeus truncate. Frontal carinae far from each other, broader than in silaceum and crassicorne. Lateral expansions of the frontal carinae broader than in silaceum and crassicorne, little raised, diverging on the two anterior fourths, converging on the third fourth, gently diverging and carinate only on the last fourth. Frontal area gently concave and with a median, longitudinal carina starting on the last fourth and prolonging backwards. Head anterolaterally with a variably marked longitudinal carina. Genal carinae marked, each carina corresponding to the external border of a deep sulcus. Eyes visible as a dark dot below the integument, small and on the middle of the head sides. First funicular joint about as long as broad. Funicular joints 2-10 broader than long. Last funicular joint about as long as the sum of joints 6-10. Scapes short of the vertexal margin and gently thickening apically. Masticatory margin of the mandibles with 7-9 denticles before the pointed apical tooth. Palp formula 2,2.

Mesosoma in side view weakly convex on the two anterior thirds, gently sloping on the posterior third. Pronotal and propodeal sutures absent. Basal face of the propodeum declivous posteriorly. Area between basal and declivous faces of the propodeum gently concave and laterally with a tooth. Declivous face of the propodeum weakly sloping posteriorly. Sides of the declivous face of the propodeum carinate. Propodeal spiracle round and above mid height in lateral view.

Petiole subrectangular, thick. Anterior border of the petiole straight and anterolaterally narrowly carinate. Ventral process of the petiole as in silaceum and crassicorne but slightly thicker. Postpetiole in dorsal view with the sides diverging posteriorly. Postpetiolar sternite anteromedially with a marked subtriangular projection, gently convex posteriorly in side view. Constriction between postpetiole and gaster impressed. Gastral tergite I about 1/3 longer than the postpetiole and convex on the curvature. Remaining gastral tergites and sternites curved ventrally.

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

Sculpture. Head, mesosoma, petiole and postpetiole punctate, reticulorugose, the reticulation and the rugosities larger on the anterolateral parts of the head, very superficial or absent on the posterior part of the head dorsum and on the anterior half of the mesosoma, the rugosities rare to sparse on the petiole and postpetiole, the punctures denser and mixed with granulation on the mesosoma, petiole and postpetiole. First gastral tergite smooth and with minute piligerous punctures, the punctures denser on the sides. Legs punctate.

Pilosity as in silaceum but with hairs of type (2) much longer and slightly denser.

Colour. Dark ferrugineous-brown with slightly lighter antennae and legs.

Measurements in mm and Indices: TL 2.62-3.02; HL 0.59-0.66; HW 0.57-0.64; EL 0.02-0.03; SL 0.37-0.42; WL 0.73-0.86; PeL 0.20-0.22; PeW 0.27-0.31; HFeL 0.39-0.48; HTiL 0.35-0.39; HBaL 0.24-0.28; LS4 0.30-0.35; LT4 0.56-0.63; CI 96.6-97.0; SI 62.3-63.6; IGR 0.52-0.55.

Queen
Baroni Urbani and de Andrade (2003) - Differing from the worker in the following details: eyes large, slightly less than 1/3 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 gently convex and with the posterior border subtruncate. Scutellum with a longitudinal carina, the carina sometimes prolonging only to the posterior half of the mesonotum and more superficial. Metanotum with a small tooth. Basal face of the propodeum almost flat laterally, concave medially, the concavity including the anteromedian part of the declivous face. Propodeal concavity dorsally variably carinate.

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

Colour. As in the worker but with a dark brown macula in the position of the ocelli.

Measurements in mm and Indices: TL 3.58-4.27; HL 0.70-0.86; HW 0.70-0.86; EL 0.21-0.26; SL 0.44-0.56; WL 1.07-1.28; PeL 0.26-0.30; PeW 0.37-0.43; HFeL 0.57-0.72; HTiL 0.45-0.58; HBaL 0.35-0.48; LS4 0.43-0.61; LT4 0.79-1.08; CI 98.6-100.0; SI 61.6-65.1 ; IGR 0.54-0.56.

Type Material
Type locality: Honduras (Cecilia). Type material: two workers labelled: Cecilia, Honduras, W. M. Mann collector, Cotype no. 24435, U.S.N.M., Proceratium mancus [sic] Mann, types; in. Note: Mann (1922) described mancum on a worker and a gyne. The two specimens labeled as cotypes in USNM, however, are both workers, though one is larger than the other.