Crematogaster nocturna

Little is known about the biology of .

Identification
Buren (1968) - This species is closely related to Crematogaster californica, the female being very similar, but the male is so distinct that there can be no question of its separation. As in californica, the male of nocturna has a shining mesoscutum and the scutellum lacks anterio-lateral impressions, but the eyes and ocelli are even larger, the sculpture of the sides of the thorax is very dissimilar, the size is much smaller, the color is lighter, and the pubescent hairs are appressed. The males and females of two other desert species, depilis and larreae, are also quite distinct from this new species in color, structure, and sculpture.

The easiest way to distinguish the females of nocturna and californica is by the shape of the head. The head is more elongate in nocturna, a little longer than broad, while it is a little broader than long in californica and is convex above and below in profile.

Key to Crematogaster of the western United States

Distribution
Northern Arizona, Utah, and Nevada.

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

Biology
Nevada, Wheeler and Wheeler (1986) - We have 5 records from 4 localities, all in the Hot Desert; 2,700-3,200 ft. Three of the nests were at the bases of larrea stems, and 4 had craters.

Nomenclature

 *  nocturna. Crematogaster (Crematogaster) nocturna Buren, 1968b: 112 (w.m.) U.S.A.

Worker
Possible (not found in association with winged forms.)

Length about 3.5 to 3. 7 mm.

Head distinctly broader than long, with strongly convex sides, the occiput a little concave, and the clypeal border evenly and gently convex, little produced. Scapes intermediate in shape between that in Crematogaster colei and in Crematogaster opuntiae and californica, apically of about equal diameter for about one-sixth or one-seventh the total length; scapes surpassing hind corners of head about one diameter or a little less. Eyes rather large, mesal and posterior borders much more convex than lateral borders which are nearly straight; anteriolateral corners almost angular.

Thorax rather slender seen from above, without obvious pronotal humeri, in profile rather flattened above as in other related species, and with mesonotal declivity gently sloping. Spines very short, straight, and somewhat divergent. Petiole of usual trapezoidal shape, but anterior corners not strongly produced, only a little broader than long. Median sulcus of the postpetiole shallow; hemilobes with rounded sides, in profile hemilobes not at all produced posteriorly so as to overhang the strigulatory surface, merely evenly and gently rounded above, thus contrasting with the condition in colei.

Head with usual parallel striae on mandibles, clypeus, and genae, those on the genae not as coarse as in most species and carried only to the front or to about the middle of the eye. Head shining, but there is usually some indistinct shagreening on the front and some very shallow but distinct puncturing on vertex and occiput and sometimes on the front. Thorax sub-shining, entirely punctate except for declivity of epinotum which is smooth, but the punctures very shallow except on lower mesopleura, this one sclerite giving an opaque effect. Base of epinotum with some rather indistinct longitudinal rugae as well as puncturing. Petiole shining, with very faint puncturation. Postpetiole shining, with faint shagreening only. Gaster shining, with shagreening only.

Very few or no erect hairs on dorsum of head; one rather short hair on each side of the pronotum; one pair of short hairs each on petiole and postpetiole; a very few erect hairs on the posterior border of each gastric tergite. Pubescent hairs of moderate length, appressed on all surfaces, including scapes and legs.

The colors in the six known specimens show a rather dark reddish brown on head, thorax, petiole, postpetiole, and basal two-thirds of first gastric segment, the remainder of the gaster black.

Queen
Length about 10 mm.

Head, excluding mandibles, subrectangular in appearance, slightly longer than broad, sides nearly straight, and posterior border excised. When seen in profile the head appears flattened above and below, and the frontal carinae are at an angle of only a few degrees from the axis of the head. Scapes very short, even shorter proportionally than in some specimens of Crematogaster californica, reaching only a little past the eyes or to the lateral ocelli. Basal funicular joints about as broad as long. Eyes large. Ocelli very large, protruding, and oval; the first ocellus looking forward and the lateral ocelli to the sides. Frontal furrow strong. Head broader than thorax. Mesoscutum much longer than wide. Scutellum wider than long. Metanotum not produced into a blunt point, similar, therefore, to californica. Epinotal spines short, little longer than diameter of base. Postpetiole with rounded spiracular angles.

Mandibles striate, without smooth sulcus at base. Clypeus with median shining streak, otherwise striate. Genal striae strong, carried past the eyes to the level of the lateral ocelli. Rear part of head smooth and shining, or faintly striate or shagreened but shining. Pronotum finely punctate, no shining area. Mesosternal sides striato-punctate; mesopleura mostly shining, sometimes with oblique striate streak. Metapleura striato-punctate. Epinotal sides finely punctate and rugose. Base of epinotum with fine, irregular, transverse rugae. Sides of petiole with fine punctures and strong striae. Postpetiole mostly punctate, especially the sides.

Pubescent hairs short and appressed on all parts. Erect hairs very sparse, usually none on thorax, a few on head and gaster.

Head and thorax reddish brown. Gaster black. Wing veins and stigma dark brown.

Male
Length about 3.8 to 4 mm.

Basal funicular joints slightly broader than long. Ocelli very large, protruding, white in color, strongly turned on their sides as in Crematogaster californica but even larger than in that species, the diameters greater than distance between them. Eyes also very large, hemispherical, occupying most of the sides of the head so that the distance between eyes and insertions of mandibles is very short. Thorax not wider than head when the head width is measured including the eyes, otherwise distinctly wider. Mesoscutum longer than wide. Scutellum with evenly curved sides, no anterio-lateral impressions. Metanotum produced into a blunt point.

Head faintly punctate or with reticulate shagreen. Mesoscutum shining, with some faint puncturing and large piligerous punctures. Pronotum with weak, coarse puncturing. Mesosternal sides punctate; mesopleura punctate except for their front angles. Metapleura striatopunctate. Sides of epinotum punctate. Base of epinotum smooth or shagreened only.

Pubescent hairs short and appressed on all parts. Erect hairs very few, only the venter of gaster with usual number.

Head and gaster brown. Thorax yellowish brown. Wing veins and stigma brown.

Type Material
Rainbow Lodge, Navajo Mts., Arizona.

Holotype male, two paratype males, and nine paratype females from Rainbow Lodge, Navajo Mts., Coconino Co., Arizona, July 14, 1933, altitude 6,500 feet- H. N. Hultgren, collector. Holotype and most of the para types to be returned to the California Academy of Natural Sciences.

Etymology
I believe the large eyes and ocelli of this species may possibly be useful in nocturnal wedding flights, hence the name.