Stenamma heathi

Stenamma heathi
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Insecta
Order:	Hymenoptera
Family:	Formicidae
Subfamily:	Myrmicinae
Tribe:	Stenammini
Genus:	Stenamma
Species:	S. heathi
Binomial name
	Stenamma heathi; Wheeler, W.M., 1915 Specimen labels

This species is known from a few collections. The only information beyond what is given in the description, and subsequent revision, comes from a litter sifting sample by Phil Ward (casent0005815): collected from leaf litter in a Sequoiadendron grove.

Identification

This is one of the more distinctive western Stenamma, most readily recognized by the peculiar sculpturation of the first tergite. Very nearly the entire segment is shagreened and finely, densely punctulate. Over the basal third of the segment extend a variable number of fine longitudinal rugulae which tend to form a reticulate pattern in some specimens. Finally, scattered over the entire segment are numerous coarse punctures, from each of which arises a long, coarse hair. The overall effect is very peculiar and is shared, in North American species, only with Stenamma exasperatum. Other western species, such as Stenamma californicum, Stenamma dyscheres and Stenamma punctatoventre have sculptured first tergites, but in these species the sculpturation consists of fine, dense punctulation and is restricted to the basal third, or less; fine longitudinal basal striae may be present or not. These species wholly lack the conspicuous coarse, piligerous punctures. (Snelling 1973)

Distribution

Mexico and USA. Smith 1957: California and Nevada. In addition to the type locality this species is known from the Yosemite and Sequoia National Parks of California and from Washoe County, Nevada. As reported in Snelling 1973: Sierra San Pedro Martir, Baja California, Mexico (col. W.S. Creighton).

Latitudinal Distribution Pattern

Latitudinal Range: 38.91667° to 36.5755°.


North Temperate	North Subtropical	Tropical	South Subtropical	South Temperate

Source: AntMaps

Distribution based on Regional Taxon Lists

Nearctic Region: United States (type locality).
Neotropical Region: Mexico.

Distribution based on AntMaps

Distribution based on AntWeb specimens

Check data from AntWeb

Countries Occupied

Number of countries occupied by this species based on AntWiki Regional Taxon Lists. In general, fewer countries occupied indicates a narrower range, while more countries indicates a more widespread species.

Estimated Abundance

Relative abundance based on number of AntMaps records per species (this species within the purple bar). Fewer records (to the left) indicates a less abundant/encountered species while more records (to the right) indicates more abundant/encountered species.

Biology

Castes

Nomenclature

The following information is derived from Barry Bolton's Online Catalogue of the Ants of the World.

heathi. Stenamma brevicorne subsp. heathi Wheeler, W.M. 1915b: 410 (w.) U.S.A. (California).
- Type-material: 25 syntype workers.
- Type-locality: U.S.A.: California, King’s River Cañon (H. Heath).
- Type-depositories: AMNH, MCZC, USNM.
- Snelling, R.R. 1973c: 31 (q.).
- Subspecies of brevicorne: Wheeler, W.M. 1917a: 520; Emery, 1921f: 54; Smith, M.R. 1951a: 795.
- Status as species: Creighton, 1950a: 137; Smith, M.R. 1957b: 154 (redescription); Smith, M.R. 1958c: 116; Snelling, R.R. 1973c: 30; Wheeler, G.C. & Wheeler, J. 1978: 391; Smith, D.R. 1979: 1359; Wheeler, G.C. & Wheeler, J. 1986g: 35; Bolton, 1995b: 393; Ward, 2005: 67.
- Distribution: Mexico, U.S.A.

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

Description

Worker

Smith (1957) - Length 2.5-3.3 mm. Second to 6th funicular segments broader than long, the last funicular segment almost as long as the combined lengths of the three preceding segments. Eye subelliptical, approximately 0.10 mm in its greatest diameter which contains from four to six ommatidia. Thorax, in profile, with variable sized mesoepinotal impression which is sometimes well pronounced and approximately twice as long as deep. Base of epinotum distinctly sloping posteriorly. Epinotal spines well developed, slender, with acute apices, approximately 0.25 to 0.33 the length of the base of the epinotum. Petiolar node, in profile, angular; from above and behind, varying from subrectangular to subconical, with truncate or weakly emarginate superior border. Postpetiolar node, from above and behind, as broad as long or broader than long, with subparallel sides except in the anterior third or fourth where the sides converge anteriorly.

Much of the head reticulate-punctate but the sculpturing not always easily seen because of the color of the head. Frontal striae present but also not always clearly discernible. Thorax above coarsely and rather irregularly reticulate, many of the interspaces often quite broad; rugulae on the anterior portion of the prothorax quite often transverse and the rugulae on the promesonotum frequently with a longitudinal trend. Petiolar node rugulose-punctate to rugulose-reticulate, punctate; dorsal surface of postpetiolar node similarly sculptured. Longitudinal rugulae at the base of the gaster not as long and prominent as in sequoiarum. Much of the first gastric segment with a shagreening and scattered punctures which gives this region a subopaque effect, especially in certain lights. Frontal area, clypeal furrow, epinotal declivity and gaster, except at noted, smooth and shining.

Hairs light yellowish or grayish, moderately abundant, but not obscuring the ground surface of the body; apparently most abundant on the gaster.

Body and appendages varying from yellowish brown or light reddish brown to dark reddish brown; the gaster usually scarcely darker than the remainder of the body.

The most notable variations in the worker are: The proportions of the head; the number and shape of the teeth on the mandible; the number of ommatidia in the greatest diameter of the eye, this ranging from about 4-6; the mesoepinotal impression often pronounced, about twice as long as deep but occasionally smaller and less well defined; petiolar node when viewed from above and behind commonly subrectangular but occasionally subconical; postpetiolar node from about as broad as long to broader than long; sculpturing on the thorax highly variable as is also the color of the body. The single Nevada worker is dark reddish brown with a blackish, first gastric segment; this segment is also more opaque than ordinarily because of the nature of the sculpturing.

Queen

Snelling (1973) - Measurements. HL 0.93-0.97; HW 0.79-0.83; SL 0.66-0.73; WL 1.33-1.40; PW 0.66-0.73.

Head. Longer than broad, CI 85-86, sides nearly parallel below, somewhat convergent toward occiput, CI 85-86. Eyes convex, of moderate size, OMD 0.83-1.00 X EL; OI 21-22. Scape stout, cylindrical at base, thickened toward apex, SI 83-89. Mandible finely rugose over entire length, cutting margin with six or seven teeth. Median lobe of clypeus of the diecki type, i.e., with longitudinal depression, laterally carinulate, appearing apically notched in frontal view. Mandibles, clypeus and frontal depression shiny; frons with divergent longitudinal rugulae to level of anterior ocellus, inters paces slightly shiny, roughened and lightly punctulate; occiput reticulate-rugulose, interspaces shiny, remainder of head reticulate-rugulose, slightly shiny and punctulate.

Thorax. Pronotal neck densely and coarsely punctulate, declivity and sides moderately shiny, lightly punctulate and reticulate-rugulose. Mesonotum longitudinally rugulose over entire length, a few reticulae toward sides and front, inters paces closely punctulate. Scutellum longitudinally rugulose, interspaces closely punctulate except in middle where punctulae are sparse and surface shiny. Pleurae moderately shiny, longitudinally rugose, interspaces punctulate, less densely so below. Sides of propodeum moderately shiny, rugose, interspaces lightly punctulate; basal face, in profile, about as long as posterior face, moderately shiny, transversely rugulose, interspaces closely punctulate; posterior face smooth and shiny; spines short, acute, about half as long as distance between them.

Petiole and gaster as described for worker (M. R. Smith, 1957).

Pilosity. As described for worker, with usual sexual differences.

Color. Light to medium ferruginous, mandibular margins and sutures darker; legs and apical flagellar segments lighter.

Type Material

Smith (1957) - Kings River Canyon (Fresno County), California. Described by W. M. Wheeler from 25 workers taken from a single colony by Professor Harold Heath. American Museum of Natural History, Museum of Comparative Zoology at Harvard College, U. S. National Museum.

Etymology

Patronym. The type specimens were collected by Professor Harold Heath.

References

Creighton, W. S. 1950a. The ants of North America. Bulletin of the Museum of Comparative Zoology 104: 1-585 (page 137, raised to species)
Smith, M. R. 1957b. Revision of the genus Stenamma Westwood in America north of Mexico (Hymenoptera, Formicidae). Am. Midl. Nat. 57: 133-174 (page 154, see also)
Snelling, R. R. 1973c. Studies on California ants. 7. The genus Stenamma (Hymenoptera: Formicidae). Contr. Sci. (Los Angel.) 245: 1-38 (page 31, queen described)
Wheeler, W. M. 1915. Some additions to the North American ant-fauna. Bulletin of the American Museum of Natural History. 34:389-421. (page 410, worker described)

References based on Global Ant Biodiversity Informatics

Johnson, R.A. and P.S. Ward. 2002. Biogeography and endemism of ants (Hymenoptera: Formicidae) in Baja California, Mexico: a first overview. Journal of Biogeography 29:10091026/
La Rivers I. 1968. A first listing of the ants of Nevada. Biological Society of Nevada, Occasional Papers 17: 1-12.
Smith M. R. 1957. Revision of the genus Stenamma Westwood in America north of Mexico (Hymenoptera, Formicidae). American Midland Naturalist 57: 133-174.
Snelling R. R. 1973. Studies on California ants. 7. The genus Stenamma (Hymenoptera: Formicidae). Contributions in Science (Los Angeles) 245: 1-38.
Vásquez-Bolaños M. 2011. Lista de especies de hormigas (Hymenoptera: Formicidae) para México. Dugesiana 18: 95-133
Wheeler G. C., and J. Wheeler. 1986. The ants of Nevada. Los Angeles: Natural History Museum of Los Angeles County, vii + 138 pp.
Wheeler, G.C. and J. Wheeler. 1978. Mountain ants of Nevada. Great Basin Naturalist 35(4):379-396