Myrmecocystus lugubris

Identification
A member of the subgenus Eremnocystus.

Key to Myrmecocystus subgenus Eremnocystus species.

Scape and propodeal dorsum without erect hairs; malar area without erect hairs or with fewer than 5 on each side; pronotum and mesonotum with at least 8 conspicuous fully erect hairs; hind femur without erect hairs on upper surface. (Snelling 1976)

Distribution
Mojave Desert of California and Nevada.

This taxon was described from the United States.

Biology
Snelling (1976) - Little is known about this species. The type locality is Mojave Desert Creosote Bush Desert. Most of the samples available are from areas of Saltbush-Greasewood Desert. Nests are located in fine sand, with a crateriform tumulus up to 10 cm in diameter. Workers forage both matinally and crepuscularly and are general food gatherers. Repletes have been collected from nests in Death Valley.

Within Death Valley, where the species is common, the elevation range is from -200' to 1600'. At Ashford Mill, in Death Valley, I found workers departing from the nest and running along a single trail toward a foraging area. The trail was very poorly defined and it is not certain it can be properly called a trail. It might be that this was merely the most commonly used route to a known foraging area.

Since the sexual forms are unknown, it follows that nothing is known of flight activities. Presumably mating flights take place after spring and/or autumnal rains.

Castes
The queen and male castes are unknown.

Nomenclature

 *  lugubris. Myrmecocystus lugubris Wheeler, W.M. 1909f: 98 (w.) U.S.A. Wheeler, G.C. & Wheeler, J. 1968: 213 (l.). See also: Creighton, 1956: 1; Snelling, R.R. 1976: 104.

Worker
Snelling (1976) - Measurements. HL 0.72-0.97 (0.78); HW 0.62-0.97 (0.68); SL 0.75-1.02 (0.85); WL 0.82-1.42 (1.15); PW 0.42-0.65 (0.46).

Head: Distinctly longer than broad in smallest workers to as broad as long in largest, CI 86-100 (87); usually shorter than scape, rarely slightly longer, SI 97-113 (109); in frontal view, sides of head straight, little narrowed toward mandibular insertions, slightly convex in largest workers; occiput, in frontal view, flat, broadly rounded at sides. Eye small, slightly longer than first flagellomere; OMD 1.22-1.75 (1.46) x EL. Mandible septendentate.

Thorax: Moderately stout, PW 0.40-0.51 (0.40) x WL. Mesonotum, in profile, nearly straight in smallest workers to moderately convex in largest, but not abruptly declivitous behind. Basal face of propodeum flat, narrowly rounded into posterior face, latter about twice as long as basal face.

Petiole: Scale, in profile, about twice higher than thick, crest narrowly rounded; from front, sides convergent above, emargination shallow, angulate; from above, about twice wider than thick.

Vestiture: Cephalic pubescence short, scattered, a little denser on occiput; thoracic pubescence abundant but not concealing surface even on pleura and propodeum; first three terga with abundant pubescence, producing sheen; third and following segments with scattered pubescence.

Cephalic hairs restricted to clypeus, frontal lobes and occiput; rarely, one or two erect hairs on malar area near mandibular insertions; longest occipital hairs less than 0.5 x MOD. Pronotum and mesoscutum with eight or more erect hairs each; metanotum and summit of propodeal declivity without erect hairs. Crest and sides of petiolar scale usually without erect hairs, rarely one or two very fine erect hairs. First and second terga with scattered short, erect, discal hairs, third and following with longer erect hairs.

Scape without erect hairs or, rarely, fewer than eight very fine short reclinate hairs; fore femur without erect hairs on inner face; all femora without erect hairs on upper surface; tibiae usually without erect hairs on outer face, rarely with up to eight fine reclinate hairs.

Integument: Clypeus polished and shiny, with scattered setigerous punctures; frontal lobes moderately shiny, finely shagreened and with sparse fine setigerous punctures; frons and occiput shinier, with scattered fine, setigerous punctures; malar area moderately shiny, with scattered elongate, setigerous punctures, denser near eyes and mandibular insertions. Thorax slightly shiny, densely shagreened; propodeum a little duller. Terga slightly shiny, finely and densely shagreened and with abundant fine, obscure piligerous punctures.

Color: Light brownish to blackish brown, appendages paler; mandibles and sides of clypeus often yellowish.

Type Material
Described from an unspecified number of worker specimens from Otis, San Bernardino Co., CALIF., collected 16 Sept. 1908 by J. C. Bradley. Cotype material in and. Lectotype, by present designation, agreeing with above basic description, parenthetical data and label data in AMNH, lectoparatypes in AMNH, MCZ.

Additional References

 * [[Media:Creighton 1956.pdf|Creighton, W. S. 1956. Notes on Myrmecocystus lugubris Wheeler and its synonym, Myrmecocystus yuma Wheeler (Hymenoptera, Formicidae). Am. Mus. Novit. 1807: 1-4 PDF]]