Stenamma punctatoventre

There is little known about the biology of this species. The type specimens were collected under a decayed limb in litter. Additional collections have been made in conifer forest, mixed forest, and riparian woodlands. Workers have typically been captured in leaf litter, under stones, or as single stray foragers.

Identification
Eyes of worker with 4-6 facets in greatest diameter and separated from mandibular insertions by 1.3-1.8 x EL; first gastric sternite and tergite both closely punctulate in part; cephalic rugulae fine, largely effaced by dense punctulation; mesopleura densely and coarsely punctate, rugulae obscure when present. Workers are medium ferruginous, but variable, usually with the cephalic dorsum being conspicuously darker and the apex of the gastric segments yellowish. (Snelling 1973)

Distribution
USA. Known from California and Washington state.

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

Nomenclature

 *  punctatoventre. Stenamma punctatoventre Snelling, R.R. 1973c: 10, figs. 12, 13, 20, 21, 55 (w.q.m.) U.S.A.

Worker
Measurements. HL 0.70-0.83 (0.75); HW 0.56-0.67 (0.60); SL 0.46-0.55 (0.50); WL 0.80-0.94 (0.86); PW 0.36-0.46 (0.43).

Head. Head a little longer than broad, CI 77-87 (80), longer than scape, slightly narrowed toward occiput. Eyes of moderate size, with 4-6 facets in greatest diameter, OMD 1.3-1.8 (1.50) x EL; OI 12-15 (13). Scape stout, a little shorter than HW, SI 76-86 (83), cylindrical, distinctly thickened near apex. Mandible with six or seven teeth, three apical teeth largest, second basal tooth reduced; mandibles shiny, striate basally, striatopunctate apically. Median lobe of clypeus slightly produced, exceeding clypeal margin; longitudinally depressed and laterally carinulate, with transverse carinula anteriorly, so it appears truncate in frontal view. Depressed frontal area shiny; frontal lobes densely punctulate and dull; remainder of head slightly shiny, densely punctulate and with fine longitudinal rugulae, forming fine reticulae above and on sides; rugulae mostly obscured by punctulation.

Thorax. Pronotal neck moderately shiny, lightly punctulate; with transverse carinula at summit of slope; dorsally with fine longitudinal rugulae which extend onto mesonotum; interspaces moderately shiny and lightly punctulate; laterally with a few obscure, widely spaced rugulae, interspaces shiny, lightly and sparsely punctulate. Mesopleura slightly shiny, densely and coarsely punctate, a few obscure longitudinal rugulae present. Sides of propodeum densely and coarsely punctate, with more distinct longitudinal rugulae; dorsum densely punctulate and slightly shiny; spines short, sharp, separated by about twice their length.

Petiole. Dorsal face of anterior peduncle about as long as anterior face of node, node cuneate in profile; peduncle below with short blunt tooth anteriorly. Postpetiole, from above, slightly broader than long, sides nearly straight; in profile, anterior face nearly vertical; without anterior projection ventrally. Sides and venter of petiole and post-petiole dull, densely punctulate; nodes a little shinier, a little more lightly punctulate, without evident rugulae.

Gaster. First tergite slightly shiny and densely punctulate basally, punctulae becoming finer and sparser to about middle of segment, apical half shiny, but not polished. First sternite densely punctulate on basal half or more.

Pilosity. With numerous scattered erect hairs, longest on clypeus and promesonotum; those of frons mostly short, but a scattering of conspicuously longer hairs.

Color. Medium ferruginous, but variable, usually with cephalic dorsum conspicuously darker; apex of gastric segments yellowish.

Queen
Measurements. HL 0.80; HW 0.66-0.70; SL 0.53-0.57; WL 1.10-1.l3; PW 0.60-0.62; wing length 4.0-4.3.

Very similar to female of Stenamma chiricahua. Head shape similar, CI 83-88; SI 78-83. Eyes proportionately a little smaller, OMD 0.66-0.75 x EL; OI 25. Clypeal structure as in worker. Cephalic sculpture as described for worker. Pronotum more finely rugulose than in S. chiricahua, interspaces much wider. Area between mesoscutal parapsides polished, without longitudinal striae, with sparse fine piligerous punctures separated by two or more times a puncture diameter. Mesopleura less coarsely striate in upper half. Basal area of propodeum smooth, without transverse rugulae. First sternite with fine striations, at least at sides. Wing venation as in S. chiricahua.

Male
Measurements. HL 0.55-0.57 (0.55); HW 0.47-0.48 (0.48); SL 0.23; WL 1.13-1.20 (1.l3); PW 0.63; wing length 3.4.

Very similar to male of S. chiricahua but eyes smaller, OI 41-42 (42); CI 83-88 (88); SI 48-50 (48). Scutellum finely lineo-punctulate. Wings similar to those of Stenamma chiricahua.

Type Material
Holotype and 15 paratype workers: Todd's Creek, about 5 mi W. Foresthill, Placer Co., CALIF., elev. ca. 1900', 24 June 1962 (R. R. Snelling), under decayed limb in litter. Allotype male and one male, four female, nine worker paratypes: Dodge Ridge, 6000', Tuolumne Co., CALIF., 6 Sept. 1967 (G. C. and J. N. Wheeler, #182). Holotype, allotype, two female and 14 worker paratypes in LACM; one male, one female, three worker paratypes in GCW; one female, three worker paratypes in MCZ; one paratype each in AMNH, USNM, ACC, WSC.

Etymology
Morphological. Combining form of punctum (dot or point) plus venter (belly), in allusion to the punctate first sternite.

References based on Global Ant Biodiversity Informatics

 * Boulton A. M., Davies K. F. and Ward P. S. 2005. Species richness, abundance, and composition of ground-dwelling ants in northern California grasslands: role of plants, soil, and grazing. Environmental Entomology 34: 96-104
 * Fisher B. L. 1997. A comparison of ant assemblages (Hymenoptera, Formicidae) on serpentine and non-serpentine soils in northern California. Insectes Sociaux 44: 23-33
 * Holway D.A. 1998. Effect of Argentine ant invasions on ground-dwelling arthropods in northern California riparian woodlands. Oecologia. 116: 252-258
 * Snelling R. R. 1973. Studies on California ants. 7. The genus Stenamma (Hymenoptera: Formicidae). Contributions in Science (Los Angeles) 245: 1-38.
 * Staubus W. J., E. S. Boyd, T. A. Adams, D. M. Spear, M. M. Dipman, W. M. Meyer III. 2015. Ant communities in native sage scrub, non-native grassland, and suburban habitats in Los Angeles County, USA: conservation implications. Journal of Insect Conservervation 19:669–680
 * Ward P. S. 1987. Distribution of the introduced Argentine ant (Iridomyrmex humilis) in natural habitats of the lower Sacramento Valley and its effects on the indigenous ant fauna. Hilgardia 55: 1-16