Proceratium poinari

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Proceratium poinari
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. poinari
Binomial name
Proceratium poinari
Baroni Urbani & De Andrade, 2003

A fossil species described from a Dominican amber specimen with additional specimens known from Mexican amber.

Identification

A member of the micrommatum clade. Resembling Proceratium micrommatum but differing from it, in the worker and gyne, by the IGR ≥ 0.23 instead of ≤ 0.16. (Baroni Urbani and de Andrade 2003)

Keys including this Species

Distribution

This taxon was described from Dominican amber, Dominican Republic (Burdigalian, Early Miocene) and is also known from Mexican amber, Chiapas, Mexico (Middle Miocene).

Castes

Nomenclature

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

  • poinari. †Proceratium poinari Baroni Urbani & De Andrade, 2003b: 178, figs. 7-10, 15-23, 25 (w.q.m.) DOMINICAN AMBER (Miocene).

Type Material

Holotype worker in the amber sample H 10-156 K-1 in Coll. POINAR, Oregon State University; 1 paratype worker in the amber sample H 10-156 K-2, same collection as the Holotype.

Unless otherwise noted the text for the remainder of this section is reported from the publication that includes the original description.

Proceratium poinari shares with Proceratium micrommatum and with Proceratium panamense the shape of the postpetiole, slightly angulate anterolaterally. poinari, in addition, shares with Proceratium mexicanum the basal face of the propodeum, denticulate and carinate.

Our attribution of the two gynes, H 10-256 G (GOPC) and PE 25 (NHMB) to poinari is based on the similarity in sculpture and gastral shape with the workers. We regard this attribution as a reasonable certainty.

The sample PE 25 includes 1 gyne and 12 males. All the remaining 15 males from other amber sarnples are very similar to those of the sample PE 25 but there are a few differences. In particular the males with reference numbers MCZC-26 & 27, MCZC 32, H 10-119, H 10-156 I and H 10-178 B have the first gastral segment slightly shorter and the petiolar and postpetiolar sculpture more marked.

The single male in Mexican amber is in rather bad shape. It appears to be deformed in a way giving it a slightly more elongate aspect. Otherwise we are unable to detect significant differences between it and the Dominican males.

Description

Worker

Head slightly longer than broad, narrower anteriorly than posteriorly. Vertex in full face view gently convex. Clypeus reduced, triangular, and 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 poorly marked. A superficial sulcus between the genal carinae and the gular area. Eyes composed by a clearly convex facet, and placed below the midline of the head. Scapes thicker in the distal half and short of the vertexal margin. First funicular joint 1/3 longer than broad. Funicular joints 2-10 broader than long. Last funicular joint about as long as the sun1 of joints 6-10. Mandibles with 3 denticles before the apical tooth. Palp formula probably 3,2.

Mesosoma slightly convex in profile. Promesonotal and propodeal sutures obsolete. Promesopleural and mesometapleural sutures impressed on the ventral half only. Basal face of the propodeum gently declivous or convex and with a superficial, transversal sulcus close to the declivous face; the sulcus posteriorly strongly carinate and denticulate laterally. Declivous face of the propodeu~n with crenulate sides. Propodeal lobes obtuse and with crenulate margin. Propodeal spiracles small and projecting.

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 1/2 or slightly less than 1/2 of the length of the gastral tergite I (LT4), in dorsal view anterolaterally angulate and with the sides weakly convex. 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 slightly angulate on the curvature, more angulate than in micrommatum. Gastral sternite I very short medially. Its sides gently protruding anteriorly and slightly obtuse. Remaining gastral tergites and sternites curved ventrally.

Legs moderately elongate. 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 third and fourth tarsomeres together, and slightly shorter than pretarsus. Pretarsal claws simple. Arolia very small.

Sculpture. Head minutely reticulate, punctate and sparsely granulate. Mesosoma, petiole and postpetiole granulate-punctate and with small, irregular foveae-like depressions. First gastral tergite superficially smooth and minutely punctate; its lateral and ventral parts granulate. Legs punctate.

Body covered by hairs of three main types: (1) short, dense, subdecumbent on the whole body; (2) long, suberect and sparse on the whole body, slightly curved, longer on the petiole, postpetiole and gaster, absent on the funiculi: (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.

Measurements in mm and Indices: TL 2.46-2.68; HL 0.56-0.61; HW 0.50-0.55; EL 0.04-0.05; SL 0.33-0.36; WL 0.68-0.72; PeL 0.27-0.30; PeW 0.20-0.21; HFeL 0.35; HTiL 0.33-0.35; HBaL 0.27-0.28; LS4 0.13-0.16; LT4 0.56-0.66; CI 89.3-90.2; SI 58.9-59.0; IGR 0.23-0.24.

Queen

(tentative attribution). Differing from the worker in the following details: eyes large and composed by many facets, shorter than 1/3 of the head length and with ocular pilosity. Ocelli well developed. Mesosoma robust and convex in side view. Parapsidal furrows weakly marked. Scutellum with the sides converging posteriorly and with the posterior border rounded. Metanotum without tooth or spine-like projection. Basal face of the propodeum very short, laterally subround, medially incised and as flat as the declivous face. Propodeal lobes subround. Petiole slightly longer than broad. Gaster slightly more angulate on the curvature.

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

Measurements in mm and Indices: TL 2.50-2.62; HL 0.53-0.55; HW 0.46-0.48; EL 0.15; SL 0.33-0.34; WL 0.67-0.76; PeL 0.22-0.27; PeW 0.18-0.24; HTiL 0.35-0.40; HBaL 0.28-0.33; LS4 0.16; LT4 0.67-0.69; CI 87.0-87.3; SI 61.8-62.3; IGR 0.23.

Male

(tentative attribution) Head slightly longer than broad. Vertex in full face view convex. Vertexal margin narrowly carinate. Clypeus medially reduced, subtriangular, separating the and slightly longer than the antenna1 sockets. Clypeal dorsum with a longitudinal carina extending posteriorly but not reaching the anterior ocellus. Antenna1 socket with broad torulus. Frontal carinae thin, low, diverging posteriorly and separate from each other. Anterior half of the rontal area gently convex, the posterior half concave. Ocelli extremely large. Compound eyes slightly less than 1/2 or about 1/2 of the head length, placed largely on the anterior head sides and with interommatidial pilosity. Scapes reaching the anterior ocellus backwards. Funicular joints 1-11 longer than broad. Last funicular joint shorter than the sum of joints 9-11. Mandibles elongate, edentate and only with a pointed apical tooth. Palp formula not clearly 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 in full dorsal view with the posterior border round. Propodeum in side view subangulate or convex. Basal face of the propodeum declivous posteriorly, sometimes weakly concave medially and weakly angulate laterally. Declivous face flat. Metanotum with a median spine-like projection. Propodeal lobes small and gently obtuse. Propodeal spiracles relatively large and slightly directed downwards.

Petiole in side view 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 variably concave and superficially carinate. Subpetiolar process in shape of 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. 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 variably punctate sparsely granulate, in some specimens the granules more marked close to the vertexal margin and on the ventral part of the head. Mesosoma smooth, with sparse punctation and variably distributed reticulation and granulation, in some specimens the reticulation broader on the pleurae. Propodeum, petiole and postpetiole irregularly reticulate-granulate and with sparse foveae-like irregular depressions; the foveae less impressed and sparse on the dorsum of the postpetiole of some specimens. First gastral tergite smooth and with minute piligerous punctures. Legs with minute piligerous punctures and granules.

Body covered by hairs of three main types: (1) short, subdecumbent or appressed on the whole body, slightly denser on the head; (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 a few sparse, suberect hairs similar to type (1).

Colour. Dark brown-black.

Measurements in mm and Indices: TL 2.27-2.46; HL 0.44-0.51; HW 0.40-0.46; EL 0.21-0.24; SL 0.29-0.35; WL 0.67-0.77; PeL 0.22-0.28; PeW 0.13-0.20; HFeL 0.45-0.55; HTiL 0.35-0.41; HBaL 0.34-0.40; LS4 0.23-0.32; LT4 0.44-0.57; CI 87.0-93.2; SI 65.9-68.6; IGR 0.52-0.56.

Etymology

This species is named after Dr. George O. Poinar, Jr. who offered us these and many other important amber specimens in study and allowed us to retain them for years.

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 178, figs. 7-10, 15-23, 25 worker, queen, male described)