Crematogaster browni

This uncommonly collected species is found in mountainous areas. Nests have been found under stones.

Identification
Buren (1968) - Although the epinotal spines are very short and often incurved in this species, as in Crematogaster ashmeadi, there seems little possibility that there could be more than a remote relationship. C. ashmeadi is strictly arboreal, has noticeably short legs, and the tarsal proportions are such that the third and fourth joints of the mid and hind tarsus are each only slightly shorter than the preceding joint. The legs in this new species are of normal length and the tarsal proportions are more differentiated as in most North American species. The females are quite different in numerous characteristics. Since there is least a 500 to 700 mi. gap between the ranges with very different ecological situations, there should be no difficulty. About the only species occurring sympatrically with which browni is likely to be confused is Crematogaster emeryana Creighton, being very similar in size and general appearance and in nesting site preferences. However, the incurved spines, narrow petiole, and long flexuous hairs which have a different arrangement, should allow an easy separation.

This is a rarely collected species that can be recognized by the tiny propodeal spines and the presence of a few erect hairs on the pronotum and none on the mesonotum. The petiole is only slighter wider (maximum width) than the postpetiole. (Mackay and Mackay 2002)

Key to Crematogaster of the western United States

Distribution
United States: known from southern Arizona and western Texas.

Occurs in the southwestern mountains mainly at approximately 4,500 to 6,500 ft.

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



Biology
Buren (1968) - My finding of browni on the tops of the Franklin Mts. in El Paso is worthy of note as it shows that this species is adaptable to a rather wide range of conditions. These mountains are treeless, and are entirely rocky and desert-like. C. browni was the only Crematogaster that I was able to find on these mountains above 5,500 to 6,000 ft. On the lower slopes at approximately 3,500 to 5,000 ft., the desert species, Crematogaster depilis Wheeler and Crematogaster larreae, n. sp. occur. This contrasts strongly with the conditions in the Davis Mts. of Texas, which at over 5,500 ft. elevations are covered by open forests of pinyon pine, juniper, and oak, and a good stand of grasses. Three ground inhabiting species occur there,  Crematogaster emeryana, browni, and Crematogaster colei, with probably emeryana'' being predominant. From the limited information available it would seem that while emeryana and browni occur together in some of the mountains of southwestern U.S., emeryana ranges considerably further northward than browni, while browni may be the only species able to colonize the tops of the barren mountains which occur throughout the Chihuahuan desert, and thus could be expected to have a considerably more extensive range in Mexico.

Nomenclature

 *  browni. Crematogaster (Crematogaster) browni Buren, 1968b: 100 (w.q.) U.S.A.

Worker
Length about 3 mm. or less, a few specimens up to 3.5 mm.

Head only slightly broader than long in most specimens, distinctly broader in largest specimens, with feebly convex sides and nearly straight or very slightly excised posterior border, slightly narrower behind the eyes than in front. Scapes surpassing hind corners by about one diameter in most specimens, only slightly surpassing in largest workers, evenly incrassated to tip. Promesonotum flattened above in profile, with short and gently sloping but distinct mesonotal declivity, this more abrupt in largest workers. Pronotal shoulders evident. Meso-epinotal impression shallow. Base of epinotum rather short; declivity with rather long, gentle slope. Spines very similar to ashmeadi in shape; short, subparallel, and convex on outer sides; a little more slender and longer than in that species, however, only a little shorter than interbasal distance. Petiole rather narrow, only very slightly wider than postpetiole. Hemilobes of postpetiole produced posterio-laterally a little, not with evenly convex sides as in many species. Proportions of femora and tarsal joints as in cerasi and lineolata rather than as in ashmeadi.

Mandibles finely striate. Clypeus finely and completely striate. Genae finely striate to about middle of eyes. Rest of head smooth and shining. Front of pronotum irregularly rugose. Dorsum of promesonotum longitudinally striate and also with fine, intercalated punctures. The striae are usually predominant on the pronotal dorsum but on the mesonotal dorsum these become very faint leaving the puncturation as the most obvious sculpture. Base of epinotum with fine striations and puncturing. Sides of pronotum with coarser but no deeper puncturing, subopaque to subshining. Mesopleura striato-punctate. Sides of epinotum very shallowly striatapunctate. Sides of epinotum very shallowly striato-punctate, subshining. Declivity of epinotum smooth and shining. Dorsum of postpetiole very finely - striato-punctate, subopaque to opaque.

Erect hairs unusually long in proportion to the size of this species, arranged as follows: usually no more than one or two or at most three pairs on head, often none; on thorax usually one long flexuous hair on each shoulder, sometimes two but no more than three per shoulder; on petiole and postpetiole the usual posterio-dorsal pairs, the pair on postpetiole often unusually long and with a characteristic bend near base and then carried directly caudad; on dorsum of first gastric tergite a few scattered hairs and seven or eight hairs in posterior row; on remaining segments a similar number or less in single rows; on venter of gaster some very long hairs. Pubescence short and closely appressed on all surfaces.

More or less concolorously dark brown to black, sometimes thorax a little lighter.

Queen
Length about 8.5 mm. to 9.0 mm.

A rather large and robust female, especially in comparison with the small worker.

Head rectangular, with straight hind border and straight or slightly convex sides. Scapes very nearly meeting hind corners of head. Mandibles usually with six teeth, occasionally with seven, thus contrasting with the mandibles of the females of most North American species which have only five. Eyes and ocelli of normal size. Thorax robust, mesoscutum about as broad as long. Post-scutal areas large. Epinotal spines long and robust, with small laterial convexities at bases. These are behind the spiracles.

Integument highly shining, even where sculptured. Genal striae rather coarse, usually not carried past the eyes. Frontal furrow distinctly impressed. Pronotum smooth on rear portion. Mesoscutum smooth but with several large, distinct, elongate piligerous foveolae near lateral edge just in front of wing insertions. Mesopleura with smaller but distinct piligerous foveolae on upper half or third. Lateral portions of mesosterum and metapleura with fine, distinct striae. Epinotum and sides of petiole striate. Metanotum apparently never produced into a definite point or process. Erect hairs moderately abundant, present on all usual surfaces. Pubescence subappressed or appressed on all surfaces, rather long.

Concolorously black or dark brown.

Type Material
Several series are known from Garden Canyon, Huachuca Mts., Ariz.- Wm. S. Creighton, collector; I have marked as the holotype a worker from one of these series and this locality therefore becomes the type locality. I have also marked as paratypes numerous examples from Canelo Pass, Santa Cruz Co., Ariz.- Wm. S. Creighton; Brown Canyon, Baboquiveri Mts.- Creighton; Sierra de San Jose, S. of Naco, Sonora, Mex. - Creighton; Nogales Ranch, Sierra de en Medio, Chihuahua, Mex.- Creighton; several series from the Franklin Mts., El Paso, Tex.- W. F. Buren; Silver City, N. Mex.- Buren; several series from near McDonald Observatory, Davis Mts., Tex.- Buren. The late Dr. L. F. Byars found this species on a number of occasions. His records, which I have also marked as paratypes, are from Montezuma Pass and Sunnyside Road Fork, both in the Huachuca Mts., Ariz.; Calabasas Ridge, Tumacacori Mts., Ariz.; and Sycamore Canyon, near Ruby, Ariz. Dr. Wm. M. Wheeler was the first myrmecologist to capture this species. His records are from the Huachuca Mts., Ariz. in 1910 and from Oracle, Ariz. in 1919 and have been marked as paratypes.

The holotype and representative paratypes are to be deposited in the National Museum. Other para types are to be sent to the Museum of Comparative Zoology, American Museum of Natural History, California Academy of Natural Sciences, to Dr. Creighton's private collection, and to the Cornell University collection. I will retain a few paratypes from each of the series.

Etymology
This new species is named in honor of Dr. Willam L. Brown, Jr., whose stature as one of the world's leading myrmecological systematists continues to grow.