Myrmica punctiventris

The most frequently collected of the species in the punctiventris group, this ant appears primarely as a forest dweller associated with the eastern deciduous forest biome. The species has been found in a variety of wooded habitats: Laurentian maple, mixed hardwoods (Culvert 1974), mixed pines, oak, oak-hickory, and mixed stands. Kannowski (1959) reported it from bogs in Michigan. From dry to humid conditions M. punctiventris seems most prosperous in mesic partly open woods. Nests are small and found in soil under litter, mosses or rocks, in acorns and occasionally in wood fragments. Wesson and Wesson (1940) report nest entrances surmounted with turrets of crude carton. Colony structure, reproduction and genetics were recently documented (Snyder & Herbers, 1991; Herbers & Mouser, 1997).

Identification
A member of the punctiventris group.

M. punctiventris differs from Myrmica pinetorum as follows: averaging larger, coarser sculpture, frontal lobes less developed and less contrast between maximum and minimum width, longer scapes and spines. (Francoeur 2007)

Distribution
Eastern North America, from southern Canada south to US Gulf states.

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

Biology
This species nests and may overwinter in hickory nuts and in acorns. Life history and natural history details of this species have been studied in great detail by Herbers and co-authors, e.g., Herbers 1989, Backus et al. 2006. They have shown this species varies in its choice of nesting location, polygyny, polydomy, allocation to growth and reproduction, and in their sex ratio. Variation is evident within and between populations, including ample evidence to show that populations are changing through time, i.e., they do not appear to have settled into expressing a stable, predictable set of traits.

Host to the parasitic Myrmica semiparasitica.

Below is a sociometric table of colony collection data.

Nomenclature

 *  punctiventris. Myrmica punctiventris Roger, 1863a: 190 (w.) U.S.A. Mayr, 1886d: 450 (q.); Emery, 1895c: 312 (m.). Senior synonym of isfahani: Weber, 1950b: 512. See also: Francoeur, 2007: 158.
 * isfahani. Myrmica punctiventris var. isfahani Forel, 1922: 92 (w.q.) U.S.A. Junior synonym of punctiventris: Weber, 1950b: 215.

Worker
Francoeur (2007) - Head in full face view subrectangular with convex sides; preoccipital margin straight and corners broadly rounded. Eyes small, convex and suboval, located slightly anteriorly of the mid point of the head sides. Anterior margin of clypeus anguloconvex; lateral wings thin and flat, with 1-3 short rugae. In dorsal view frontal lamellae laterally feebly developed over the antennal articulation, approximately triangular or anguloconvex in shape; posterior margin weakly narrower and ending as a carina merging into the head dorsum. Antennae: fossae rather shallow; scapes shorter than head length; in profile base evently bent, dorsoventrally flattened with a feeble dorsal concavity; in dorsal view shaft width regular along its axis. Funiculus segments 3-5 as large as long, others longer than broad; apical club of 4 segments.

Mesosoma in profile, mesometasternum external margin horizontally aligned, promesonotum very feebly convex, almost straight in larger specimens, distinctly higher than propodeum, both joining through an angle at the mesopropodeal furrow which remains shallow. In dorsal view promesonotum typically pear-shaped, posterior end of mesonotum narrower and anguloconvex. Strigil of protibia with basal tooth; meso- and metatibiae with delicate spurs, finely pectinate on the distal half. Propodeal lobes small, with a posterodorsal angle. Propodeal spines long and acuminate with a narrow base, longer than the distance separating their tips, projecting backwards and upwards, either almost straight or most often deflected, usually subparallel. Petiole short, about as high as long but narrower; peduncle hidden by propodeal lobes; anterior face of node seen in profile slightly concave, forming a right angle with the somewhat flattened dorsal surface, concave posterior face inclined down to posterior margin. Postpetiole shorter than high and wide, height and width about equal; node profile typically with very short anterior and posterior vertical surfaces, united by a large convex one; sternal process strongly convex and globular, making 1/3 of the postpetiole height.

Mandibles striate with piligerous punctures. Frons and clypeus with parallel, coarse rugae, separated by subopaque, faintly microsculptured surface; reminder of head with reticulation. Mesosoma generally striatorugulose; rugae thicker on pleurae and somewhat sinuous on promesonotum. Antennal fossae with parallel and convex rugae. Petiole and postpetiole rugose. Gaster smooth and shining; first segment with large round punctures. Long erect hairs moderately abundant on body; suberect on scapes. Gastric dorsum without distinct pubescence. General body color light to dark reddish brown; gaster darker; appendages lighter or more yellowish.

Queen
Francoeur (2007) - Basically similar to workers in shape of head, characters of sculpture, color and pilosity of body but with the following usual caste differences: three ocelli present; mesosoma modified for flight; body size larger. Sculpture coarser on posterior half of dorsum of head, on petiole and postpetiole. Mesosoma coarsely rugose; surface between rugae faintly microsculptured. Mesopleural transverse groove rather large and shallow, impressed; katepisternum with widely spaced, oblique, parallel rugae. Surface between spines smooth and shining. Wings tinted brownish. Submarginal cell of anterior wing partly subdivided.

Male
Francoeur (2007) - Smaller than queen. In full face view head slightly longer than broad, narrower before eyes, with shallow elongated antennal fossae, posterior half evenly rounded. Mandibles elongate, blade subtriangular; masticatory margin with three apical teeth followed by 2-3 denticles. Clypeus convex, anterior margin angulate. Malar space short. Frontal triangle shallow and weakly delimited. Frontal lobes poorly developed, but distinct, as thin carinae with straight lateral margins that diverge posteriorly, originating from toruli. Antennae 13-merous; scapes very long, equal to first 6-7 funicular segments; in profile scape base with faint dorsal flattening; length of second funicular segment equal to the length of next two; club 5-merous. Eyes large and globular. Ocelli rather large, 0.07-0.09 mm in diameter; distance between posterior ocelli 3-4 x diameter of anterior ocellus.

In lateral view, mesosoma elongate; mesonotum high. Mayrian furrows not impressed, weakened or absent posteriorly. Mesoscutellum anguloconvex posteriorly in dorsal view. Spurs of meso- and metatibiae pectinate. Metapleural lamellae small. Wings as in queen, usually darker. Propodeum with more or less developed prominences marked by carinae, sometimes spiniform, surface between them smooth and shining; spiracles rounded and well marked. In profile petiole short, with anterior peduncle mostly hidden by propodeal lobes; ventral margin straight or very weakly concave with an anterior denticule; node with anterior slope straight, summit rounded with horizontal rugulae. Postpetiole shorter, slightly wider than long; in profile higher than long; anterior and dorsal surfaces of dorsum forming a convex slope with apex posterior to center; sternum longer than high, ventral margin straight or convex.

Head sculpture generally fine; rugulae present on front, shorter and stronger around eyes and malar space, anastomosed on temples, surface punctulate. Mandibles subopaque, faintly sculptured. Clypeus faintly sculptured, often with short median ruga extending back anterior margin. Frontal triangle punctulate. Frons with rugulae reaching the ocellar triangle, median part often only punctulate and shining; lateral lobes reduced to feebly lamellar parallel carinae originating from toruli. Temples punctate, with a varying abundance of short, partly anastomosed rugulae. Antennal scapes with suberect hairs over pubescence, most shorter than width of scape; funiculi with few short, suberect fine hairs on segments over the pubescence, sparse on club. Mesosoma generally rugulose. Pronotum partly shagreened and mesoscutum partly smooth and shining; mesoscutellum with longitudinal rugulae; mesopleuron with stronger rugulae on dorsoposterior corner of katepisternum; anepisternum with an anterior smooth area; transverse grooves feebly impressed, dark. Propodeal protuberences with a row of fine erect hairs. Petiole node with rugulae. Postpetiole node smooth and shining with lateral shagreening; sternum with rugulae. Body pilosity moderately abundant, fine, erect to decumbent; denser on legs. Gaster smooth and shining; first segment with very faint punctures. Body color black to blackish brown; appendages lighter.

Type Material
Francoeur (2007) - North America (according to Creighton, 1950). Based on known range: eastern N. A. Type material, if still in existence, should be in the Berlin Museum.