Neivamyrmex californicus

Snelling and Snelling (2007) - This species appears to be primarily an ant of montane and foothill areas. Little is known about the feeding preferences of this species other than that it presumably attacks exclusively, or nearly so, other ant species. Ward (1999) lists the following as prey species of this ant: Messor andrei, Solenopsis molesta, Pheidole californica and Pheidole hyatti. One of us (GCS) observed a portion of a raid on a Solenopsis xyloni colony; the raid was well underway when it was discovered. It was apparently a violent one with S. xyloni vigorously defending its nest. Whether or not the raid was successful from the standpoint of N. californicus is unknown but the ground was littered with dead and dying of both species. The wingless phorid fly, Xanionotum hystrix Brues (Diptera: Phoridae), has been associated with a colony of N. californicus collected in San Diego County, California (J. H. Hunt, pers. comm.).

Identification
Smith (1942) - The worker of californicus can be distinguished by the slender petiole, which is distinctly longer than broad; the straight margin on the superior border of the mandible, lying between the basal tooth and the masticatory border; the rather small, somewhat indistinct eyes; the frontal carina not forming a distinct flange in front of the antennal socket; the shining head, promesonotum, propleura, postpetiole, and gaster; the reddish brown body with lighter gaster; and by the moderately abundant hairs of variable length, those on the scapes, dorsum of body, legs, and venter being unusually long and suberect to erect.

The worker can be distinguished from that of Neivamyrmex opacithorax by its more feebly sculptured and therefore more shining body, this being especially true of the promesonotum; generally longer and more erect hairs of the body; less distinct eyes; and usually lighter color. Eciton opacithorax was formerly considered a subspecies of californicus but was later raised to specific rank.

Key to the Neivamyrmex species of the United States

Distribution
United States: California. Mexico: Baja California.

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

Castes
The male caste is unknown.

Nomenclature

 *  californicus. Eciton californicum Mayr, 1870b: 969 (w.) U.S.A. Watkins, 1972: 364 (q.). Combination in E. (Acamatus): Emery, 1894c: 182 (in text); in E. (Neivamyrmex): Smith, M.R. 1942c: 560; in Neivamyrmex: Borgmeier, 1953: 8. Senior synonym of obscura: Borgmeier, 1955: 517. See also: Ward, 1999a: 76; Snelling, G.C. & Snelling, R.R., 2007: 467.
 * obscura. Eciton (Acamatus) californicum var. obscura Forel, 1914d: 265 (w.) U.S.A. [Unresolved junior primary homonym of obscurum Forel, above.] Junior synonym of californicus: Borgmeier, 1955: 517.

Worker
Smith {1942) - Major. Length 3-4 mm.

Head scarcely longer than broad; narrowed posteriorly; posterior border emarginate, forming produced, but blunt, angular corners. Eye rather small, ocellus-like, not easily discernible. Mandible of same general shape as that of opacithorax. Scape moderately robust, approximately three and two-tenths times as long at broad; when fully extended backward noticeably surpassing posterior border of eye; funiculus not especially robust. Frontal carina not forming a distinct flange in front of antennal socket as in wheeleri and leonardi. Thorax,- from above, widest in region between fore coxae; promesonotum rather convex; a weak but distinct transverse carina on anterior part of prothorax. Epinotum clearly lower than mesonotum but not separated from it by a very distinct suture. Petiole, in profile, longer than high, convex above, with a blunt but definite anteroventral tooth. Postpetiole convex above, higher than long, highest posteriorly. Petiole, from above, slender, distinctly longer than broad, broadest posteriorly. Postpetiole subtrapezoidal, shorter but distinctly broader than petiole, and broader posteriorly than anteriorly.

Noticeably shining with the following exceptions: Mandibles, funiculi, meso- and meta pleura, epinotum, petiole, and tarsi, which are slightly subopaque.

Mandibles striate-punctate; meso- and metapleura, epinotum, and petiole with granulate shagreening. Head with sparse, scattered punctures. Dorsum of thorax and petiole with scattered, foveolate punctures, best seen only in certain lights.

Pilosity yellowish, moderately abundant, of variable length, suberect to erect. Antennal scapes, dorsum of body, ventral surface of gaster, and legs with sparse but very long, suberect to erect hairs.

Light to dark reddish brown, with distinctly lighter gaster.

Type Material
Smith (1942) - Type apparently in the Gustav Mayr collection of the Naturhistorisches Museum in Vienna.

Determination Clarifications
All previous out of state records (beyond California) believed to apply to this species have proven to refer to the recently recognized shiny headed form of Neivamyrmex nigrescens (Ward 1999). Watkins (1972) described what he believed was the queen of N. californicus, however recent reexamination of the specimen in question (Ward, 1999) has led to the conclusion that it too is a representative of the shiny form of N. nigrescens. (Snelling and Snelling 2007)