Proceratium dominicanum

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Proceratium dominicanum
Temporal range: Burdigalian, Early Miocene Dominican amber, Dominican Republic
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Proceratiinae
Tribe: Proceratiini
Genus: Proceratium
Species: P. dominicanum
Binomial name
Proceratium dominicanum
De Andrade, 2003

A fossil species described from Dominican amber specimens.

Identification

A member of the micrommatum clade. Resembling Proceratium taino and Proceratium mexicanum, in the gyne, but differing from both by the following measurements and indices: TL < 3.10 mm (instead of > 3.70 mm) and IGR ≥ 0.24 (instead of ≤ 0.20). dominicanum resembles taino and mexicanum in general body shape. dominicanum shares only with mexicanum the basal face of the propodeum laterally angulate or denticulate and only with taino the mid basitarsi without a hair long 1/2 or more than the mid basitarsus. dominicanum has the second gastral sternite less protruding anteriorly than mexicanum and less flattened than taino. (Baroni Urbani and de Andrade 2003)

Distribution

This taxon was described from Dominican amber, Dominican Republic (Burdigalian, Early Miocene).

Castes

Nomenclature

The following information is derived from Barry Bolton's New General Catalogue, a catalogue of the world's ants.

  • dominicanum. †Proceratium dominicanum De Andrade, in Baroni Urbani & De Andrade, 2003b: 182, figs. 4-6, 11-13 (q.m.) DOMINICAN AMBER (Miocene).

Description

Queen

Head longer than broad, narrower anteriorly than posteriorly. Vertex in full face view weakly convex. Clypeus reduced, triangular, slightly longer than the antennal sockets. Antennal socket with broad torulus. Frontal carinae close to each other, not covering the antennal insertions. Frontal area behind the frontal carinae weakly convex. Lateral expansions of the frontal carinae relatively narrow, raised and diverging. Genal carinae marked. A superficial sulcus between the genal carinae and the gular area. Eyes large, slightly shorter than 1/3 of the head length and with ocular pilosity. Ocelli well developed. Scapes thicker in the distal half and not reaching the anterior ocellus posteriorly. First funicular joint 1/3 longer than broad. Funicular joints 2-10 broader than long. Last funicular joint about as long as the sum of joints 6-10. Mandibles with 4 denticles before the apical tooth. Palp formula probably 3,2.

Mesosoma robust and convex in profile. Parapsidal furrows marked. Scutellum with posteriorly converging sides and with the posterior border rounded. Metanotum with a triangular tooth. Basal face of the propodeum short, clearly angulate or denticrrlate laterally, incised and as flat as the declivous face medially. Propodeal lobes weakly round or obtuse. Propodeal spiracles small.

Petiole longer than broad, with the sides subparallel in the anterior third and convex posteriorly in dorsal view. Anterior border of the petiole concave, carinate and angulate on each side. Ventral process of the petiole small and subtriangular. Postpetiole slightly shorter than 1/2 of the length of the gastraI tergite I (LT4), anterolaterally gently angulate and with the sides weakly convex in dorsal view. Postpetiolar sternite anteromedially with a subtriangular projection. Posterior half of the postpetiolar sternite slightly convex. Constriction between postpetiole and gastral segment I deeply impressed. Gastral tergite I convex on the curvature. Gastral sternite I very short medially. Sides of gastral sternite I not protruding anteriorly. Remaining gastral tergites and sternites curved ventrally.

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

Mid tibiae without 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 mid and hind legs longer than the third and fourth tarsomeres and slightly shorter than pretarsus. Pretarsal claws simple. Arolia very small.

Sculpture. Head, mesosoma, petiole and postpetiole granulopunctate, the punctation more superficial on the pronotum and mesonotum and irregular on the petiole and postpetiole, the granules sparse and small close to the vertexal margin and on the mesosoma, dense and larger on the petiole and postpetiole. Some specimens have the lower metapleurae with additional, thin, irregular longitudinal rugosities. First gastral tergite superficially smooth and minutely punctate; its sides and the ventral part reticulate-punctate and sparsely granulate. Legs punctate.

Body covered by hairs of three main types: (1) short, dense, subdecumbent on the whole body; (2) long, suberect and sparser than in poinari on the whole body, longer on the postpetiolar sternite; (3) shorter than hair type (1), dense, decumbent on the funicular joints only. In addition the funicular joints bear whitish, thick, appressed, sparse hairs and suberect hairs similar to type (1) but slightly shorter.

Colour ferrugineous-brown or dark brown.

Measurements in mm and Indices: TL 2.80-3.08; HL 0.60-0.67; HW 0.52-0.56; EL 0.17-0.20; SL 0.36-0.42; WL 0.83-0.89; PeL 0.30-0.3 1; PeW 0.21-0.24; HTiL 0.37-0.42; HBaL 0.27-0.35; LS4 0.17-0.2 1 ; LT4 0.67-0.80; CI 84.1-86.6; SI 60.0-63.5; IGR 0.24-0.26.

Male

(tentative attribution). Head longer than broad. Vertex in full face view convex. Vertexal margin narrowly carinate. Clypeus medially reduced, triangular, slightly longer than the antennal sockets. Clypeal dorsum with a longitudinal carina extending posteriorly but not reaching the anterior ocellus. Antenna1 socket with broad torulus. Frontal carinae thin, very low, diverging posteriorly and separate each other. Anterior half of' the frons gently convex, the posterior half concave. Ocelli very large. Con~pound eyes slightly shorter than half of the head length, placed largely on the anterior part of the head sides and with ocular pilosity. Scapes slightly surpassing the vertex. Funicular joints 1-11 about half longer than broad. Last funicular joint longer than the sum of joints 10-11. Mandibles elongate, edentate and only with a pointed apical tooth. Palp formula not visible.

Mesosoma robust. Pronotum and anterior third of mesonotum almost perpendicular to the posterior two thirds of the mesonotum. Posterior two thirds of mesonotum gently convex. Parapsidal furrows marked. Scutellum higher than the mesonotum and with the posterior border round in full dorsal view. Propodeum in side view weakly convex. Basal face of the propodeum declivous posteriorly and weakly concave medially. Declivous face flat. Metanotum with median spine-like projection. Propodeal lobes small and obtuse. Propodeal spiracles slightly directed downwards.

Petiole in profile declivous on the anterior third and convex on the two posterior thirds, with parallel sides in the anterior third and convex on the two posterior thirds in dorsal view. Anterior border of the petiole concave and carinate. Subpetiolar process forming a narrow, subtriangular lamella. Postpetiole anteriorly slightly broader than the petiole; postpetiolar sides diverging and gently convex posteriorly. Anterior border of the postpetiolar sternite with a projecting triangular "lip".

Gastral tergite I round. Gastral sternite I broad in the middle. Remaining gastral tergites and sternites curved ventrally.

Legs elongate. Spurs of fore legs without basal spine. Mid tibiae without spur. Hind basitarsi about as long as the hind tibiae.

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

Sculpture. Head reticulate-punctate, vertexal margin with sparse granulation. Mesosoma, petiole and postpetiole reticulate-punctate granulate; this sculpture very superficial on the dorsum of the mesonotum; the reticulation larger and mixed with irregular foveae-like depressions on the scutellum, propodeum, petiole and postpetiole. First gastral tergite smooth and with minute piligerous punctures. First gastral sternite punctate and irregularly reticulorugose. Legs with minute piligerous punctures and granules.

Body covered by hairs of three main types: (1) short, subdecumbent or decumbent on the whole body; (2) long, suberect and sparse on the whole body; (3) shorter than hair type (1), dense, decumbent on the funicular joints only. In addition the funicular joints bear sparse, suberect hairs similar to type (1).

Colour. Black.

Measurements in mm and Indices: TL 3.05; HL 0.57; HW 0.50; EL 0.25; SL 0.46; WL 0.96; PeL 0.28; PeW 0.1 8; HFeL 0.75; HTiL 0.52; HBaL 0.51; LS4 0.40; LT4 0.76; CI 87.7; §I 80.7; IGR 0.53.

Type Material

Holotype winged gyne in the Dominican amber sample Do-5 188 of the collection of Staatliches Museum fur Naturkunde Stuttgart.

Etymology

dominicanum is a neologism indicating the provenance from the Dominican Republic.

References

  • Baroni Urbani, C., de Andrade, M.L. 2003. The ant genus Proceratium in the extant and fossil record (Hymenoptera: Formicidae). Museo Regionale di Scienze Naturali, Monografie, 36, 1–492. (page 182, figs. 4-6, 11-13 queen described)