Crematogaster hespera

Buren (1968) noted this species was largely arboreal and favored large cottonwood trees growing along riverbanks. They are also found in other trees and in downed logs. Mackay and Mackay (2002) - reported for New Mexico: This species nests in the soil, usually under stones. Brood was found in nests from May to August, sexuals in August. Foragers tend coccids on the roots of snakeweed (Gutierrezia sarothrae). They are attracted to baits, including rotten liver and tuna fish.

Identification
Buren (1968) - This form may be easily distinguished from Crematogaster laeviuscula by the finely striate thorax, the evenly but not strongly convex profile of the promesonotum without mesonotal declivity, the less divergent, often incurved epinotal spines wth the little oblique impressions at base, the differently shaped postpetiole and by the fact that the larger workers do not exhibit as much allometry as in laeviuscula. The females differ in having the genal striae not carried as far back as in laeviuscula, the scapes a little longer, and the sides of the epinotum less sculptured. The easiest way to distinguish the females of the two species is perhaps by the shape of the scutellum. This sclerite has weak anterio-lateral impressions in hespera so that the outline seen from above between scutellum and each posterior mesoscutal area is distinctly indented and the posterior mesoscutal areas are much more convex laterally than in most species. The females of hespera also seem somewhat smaller.

Because of the striate thorax, hespera might be mistaken for Crematogaster cerasi, but the latter always exhibits a distinct angular mesonotal declivity in the large specimens and the epinotal base and spines are dssimilar. The females of hespera and cerasi are somewhat similar but differ in color; the frontal furrow of hespera is weak as in laeviuscula rather than strong as in cerasi; and the tarsi of hespera are more slender, the hind fourth tarsal joints not bilobed seen from above. They are feebly bilobed in cerasi.

Key to Crematogaster of the western United States

Distribution
California and east to western Texas, north to Utah; Sonora and Lower California.

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



Habitat
Buren (1968) - Most of the records are from stations between 2000 to 5500 feet in altitude except the west coast finds. The favored habitat seems to be the large cottonwood trees growing along streams. Mackay and Mackay (2002) - Chihuahuan Desert, creosotebush scrub up to pinyon juniper forests (5600 ft.), occasionally in riparian areas.

Biology
Nevada, Wheeler and Wheeler (1986) - We have 5 records from 5 localities; 3,900-6,300 ft. Churchill Co.: 5 mi. SSW Fallon 3,900 ft., in cottonwood grove in an irrigated farmyard; the nest was in an exposed cottonwood root and in a piece of rotten wood in a cavity under the bark (Fig. 30). Lyon Co.: 6 mi. SE Wabuska 4,300 ft., in a cottonwood grove, workers in a procession up and down a cottonwood trunk. Nye Co.: Fairbanks Spring. Washoe Co.: Washoe Lake 5,100 ft., on a sand dune in loose sand at base of Prunus andersonii; Incline Village, in house, producing frass, 6,300 ft.

Nomenclature

 *  hespera. Crematogaster (Crematogaster) hespera Buren, 1968b: 98 (w.q.) U.S.A.

Buren (1968) - The question of whether hespera is a good species or instead must be considered as a geographical subspecies of Crematogaster laeviuscula is difficult to decide at present in spite of what would seem to be sufficient sampling in the areas involved. C. laeviuscula appears to fade out in west Texas, whereas hespera appears west of the Chisos and Davis mountains in westernmost Texas and then occurs throughout the southwest and on into California. Perhaps more collecting in Mexico would settle the matter. C. laeviuscula is certainly numerous enough in Tamaulipas just east of the Sierre Madre Oriental, while the western slopes of these mountains and the central plateau where hespera might possibly occur have not been sufficiently collected. Probably the most likely area to sample to discover either the overlapping zone or the intergradation zone would be a thorough exploration of the Rio Grande River bottom lands from Del Rio to El Paso, Texas.

Worker
Length about 3 to 4.5 mm.

Head, excluding mandibles, broader than long, with convex sides and straight or slightly excised posterior border. Scapes surpassing hind corners by about one diameter. Humeri of pronotum not very evident. Thorax slender. Pro-mesonotum in profile evenly but not strongly convex; without mesonotal declivity. Meso-epinotal impression weaker than in many species. Base of epinotum in profile often convex and cut off from the bases of the spines by oblique impressions. Spines slender, sharp, not very divergent and often incurved at the tips, directed somewhat upward also. Postpetiolar hemilobes longer than broad, with some tendency to be semiangulate behind; spiracular corners not accentuated.

Genal striae not carried past the eyes or only to the middle of the eyes. Head shining on front, vertex, occiput, and corners, sometimes faintly punctate on vertex. Front of pronotum finely rugose. Dorsum of promesonotum longitudinally striate. Base of epinotum also longitudinally striate, the striae often carried right through the mesoepinotal impression from the mesonotum. Striae of epinotum not carried onto the spines but interrupted at bases by the oblique impressions. Pronotal sides finely striate. All the above sclerites shining even though striate. Mesopleura punctate. Metapleura striate or striate with fine punctures. Postpetiole finely punctate.

Pubescence short and appressed on all parts. Erect hairs slender, only a few on pronotal shoulders and at rear of mesonotum. On the gaster mostly confined to the single rows near the posterior borders of each segment.

Head and thorax yellowish red. Gaster black.

Queen
Length about 7 mm.

Head, excluding mandibles, much broader than long, the posterior border excised, and sides a little convex. Scapes reaching slightly past corners. Basal funicular joints about as broad as long. Ocelli small. Head much broader than thorax. Mesoscutum a little longer than broad. Scutellum distinctly wider than long, with weak anterio-lateral impressions. Epinotal spines short, little or no longer than diameter of bases. Base of epinotum with median impression. Spiracular angles of postpetiole not strong, somewhat rounded. Tarsal joints slender, hind fourth tarsal joints not bilobed seen from above. Epinotal lateral convexities usually moderate, sometimes strong, but evenly convex in either case, never tuberculate.

Mandibles striate, with smooth sulcus at base. Clypeus with wide median shining streak, rest striate. Frontal furrow weak. Genal striae not carried past the eyes. Rest of head smooth and shining. Front of pronotum finely roughened and striate, smooth on middle and rear. Mesosternal sides strongly striate: mesopleura smooth. Meta pleura striate. Sides of epinotum faintly striate or nearly smooth. Base of epinotum with faint rugae directed toward the spines. Sides of petiole usually only finely punctate. Postpetiole smooth above.

Pubescent hairs short on all parts, subappressed on head and thorax, appressed on gaster. Erect hairs rather sparse.

Head and thorax yellowish red, with three elongate infuscated spots on mesoscutum along the anterio-median and parapsidal sutures. Gaster reddish black or black. Wing veins and stigma pale yellow.

Type Material
Phoenix, Arizona

Types: Holotype worker and eleven para type workers from Phoenix, Arizona, July 20, 1918- A. W. Morrill, with the note “attacking unripe peaches, very destructive.” I have another series from Phoenix of ten paratype workers and three females collected Dec. 25, 1895. The latter series was seen by Emery and marked by him as transitional from laeviuscula to cerasi. I have marked as paratypes also numerous specimens from these localities: Big Dalton Canyon, Glendora, Calif.- A. Mallis and J. Schwartz; Col. Desert, Calif. -A. L. Pickens; Glenville, Calif.- A. Wetmore; Pacific Grove, Calif.- W. M. Mann; Sacaton, Ariz.- F. S. Strickney; Nogales, Ruby, and Patagonia, Ariz.- L. F. Byars; Las Cruces, N. Mex.- A. C. Cole; Nogales and Patagonia, Ariz., and Ysleta and El Paso, Tex.- W. F. Buren; Sacramento, Calif.- P. H. Arnaud; Santa Ysabel and Mt. Laguna, San Diego Co., Calif.; Ft. Huachuca, Wickenberg, and Patagonia, Ariz.; and Imuris, Sonora, Mex.- Vv. S. Creighton; and Tempe, Ariz., W. M. Wheeler. A few other paratype specimens are known from "Los Angeles Riv., Calif.," Ventura and Pasadena, Calif., Tucson, Ariz., and Zion Canyon, Utah.

Holotype and many of the above paratype specimens are to be returned to the National Museum. Other para types will be returned to the California Academy of Natural Sciences and to the private collections of Dr. A. C. Cole and Dr. Wm. S. Creighton. I will retain a few paratypes from some of the series and deposit some of the paratypes in the Museum of Comparative Zoology.