Myrmecocystus kathjuli

This species has only been collected a few times and little is known about its biology.

Identification
A member of the kennedyi group of the Myrmecoystus subgenus Endiodioctes.

Key to Myrmecocystus subgenus Endiodioctes species.

Snelling (1976): Worker - Malar area with few erect hairs; pronotal hairs short, stiff; third tergum with abundant appressed pubescence; gaster black, but with mediobasal yellow blotches on first and second terga; CI usually (over 80%) less than 90; mandible octodentate. Female: penultimate segment of maxillary palp more than twice as wide in basal third as at apex; malar area with numerous very long, flexuous hairs; gaster ferruginous; thorax black with extensive ferruginous markings. Male: Ventral lobe of aedeagus convex in profile; mesoscutum uniformly tessellate, moderately shiny; petiolar node sharply cuneate, crest, from front, deeply incised; first three terga with abundant pubescence in middle; longest occipital hairs at least 0.75 x MOD; wings without fringe hairs; some mesoscutal hairs exceeding EL.

This species is most similar to such species as Myrmecocystus nequazcatl, Myrmecocystus wheeleri and Myrmecocystus kennedyi. The characteristics of the female are very similar to those of wheeleri, the only other species with a ferruginous gaster in this caste. The female of wheeleri is more extensively ferruginous on the thorax than that of  Myrmecocystus kathjuli, but this is probably subject to too much variation to be useful. At present only the much longer cephalic and thoracic pilosity of kathjuli will separate the females of these species.

The shorter pronotal hairs will distinguish the worker of kathjuli from those of nequazcatl and wheeleri; the bicolored gaster will separate it from these and kennedyi. From kennedyi, which also has short pronotal hairs, further distinction lies in the consistently broader head of kennedyi, CI in excess of 90 in 88% of the specimens studied. No other species in this complex has eight-toothed mandibles.

Pale workers of Myrmecocystus flaviceps resemble this species but are recognized by the more abundant cephalic and thoracic pubescence, hence duller appearance, and broader head, in which CI exceeds 90 in more than 80% of the specimens studied. Also, the range of flaviceps in the Mojave Desert lies to the east of that of kathjuli.

Distribution
United States. Known only from the western Mojave Desert of California.

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

Biology
The few records of this ant are all from Creosote bush desert where Joshua trees (Yucca brevifolia) are present. Known elevational amplitude is a little over 1000 feet, extending from 2355-3500'. Nests are constructed in desert washes in deep sand and are surmounted by a low broad crateriform tumulus up to 17 em in diameter. Foraging is diurnal, and the workers have been collected at floral nectaries. The sexual forms were present in the type series nest on 31 Mar. 1972 and a dealate female was taken on the ground at Red Rock Canyon on 1 May 1971.

Nomenclature

 *  kathjuli. Myrmecocystus (Endiodioctes) kathjuli Snelling, R.R. 1976: 59, figs. 92-99, 160, 172, 185, 193 (w.q.m.) U.S.A.

Worker
Measurements. HL 0.95-1.23 (1.23); HW 0.77-1.17 (1.17); SL 1.17-1.53 (1.53); WL 1.5-2.2 (2.2); PW 0.60-0.90 (0.90).

Head: Distinctly longer than broad in all sizes, CI 82-95 (95) much less than SL, SI 115-132 (124); in frontal view, broadest below level of eyes, sides straight or very slightly convex, hardly narrowed toward mandibular insertions. Occiput, in frontal view, slightly convex, evenly rounded into sides through barely perceptible corners. Eye small, 0.98-1.00 (1.00) x first flagellomere; OMD 1.53-1.89 (1.89) x EL. Mandible with eight teeth.

Thorax: Slender, PW 0.36-0.44 (0.41) x WL. Mesonotum evenly sloping to metanotum. Propodeum higher than long; in profile, wholly convex from base to apex, without defined basal and posterior faces. Petiole: In profile, broadly cuneate, with rounded crest; from behind, crest flat or gently convex, without median notch.

Vestiture: Cephalic pubescence reduced, sufficiently dense to impart a sheen only on occiput; pubescence moderately dense on thorax and first three terga.

Malar area with six or fewer fine erect hairs; longest occipital hairs little shorter than EL, much exceeding MOD. Pronotum with about 8-12 erect hairs, longest equal to about 0.5 x MOD; mesonotum with about twelve erect hairs, longest less than 0.5 x MOD; propodeum with about an equal number of similar hairs. Crest and sides of petiolar scale with a few fine erect hairs. First three terga with discal hairs sparse, shorter than apical thickness of hind tibia, hairs longer on margins, on succeeding segments and on sterna. Short, erect hairs numerous on anterior and lateral scape surfaces, all surfaces of femora (except inner face of fore femur) and exterior surface of tibiae.

Integument: Head polished and shiny, with scattered fine punctures, coarser and denser on frontal lobes; mandible finely striate and with scattered coarse punctures. Thoracic dorsum moderately shiny, lightly shagreened, sides and propodeum duller, more densely shagreened. Terga slightly shiny, densely shagreened and closely micropunctate.

Color: Head, thorax and appendages clear light ferruginous; gaster blackish brown, first two or three terga with large, yellowish, median blotches.

Queen
Measurements. HL 1.90-2.00; HW 1.90-2.10; SL 1.17-1.53; WL 1.5-2.2; PW 0.60-0.90.

Head: As broad as long or broader, CI 100-105, slightly longer than scape, SI 95. In frontal view, broadest at level of antennal socket, then convergent toward mandibular insertion. Occiput, in frontal view, gently convex, lateral corners broadly rounded. Eye small, about 1.2 x length of first flagellomere; OMD 1.55-1.75 x EL. OOD 3.0-3.7 x OD; IOD 2.5-2.7 x OD. Mandible with ten or eleven teeth. Penultimate segment of maxillary palp much narrowed apicad, mote than twice broader in basal third as at apex.

Thorax: Robust, PW 0.57-0.62 x WL. Posterior half of scutum and anterior half of scutellum forming an even, flattened plane. Basal face of propodeum distinct, sloping toward posterior face which it meets in a weakly defined angle.

Petiole: Compressed in profile, apex very narrowly truncate; in frontal view, crest deeply, angularly incised.

Vestiture: Pubescence sparse over most of head, longer, denser on occiput and malar area, generally appressed, but some on occiput decumbent. Thoracic pubescence dense on pronotum, sides and propodeum, sparse on scutum (but denser on parapsis) and scutellum. First five terga with dense appressed pubescence.

Side of head, in frontal view, with numerous long, flexuous, fully erect, hairs; occipital hairs erect, slender, flexuous, many exceeding EL. Mesoscutum with sparse, fully erect hairs, some of which nearly equal EL; scutellum with some much longer hairs. Pleura with scattered long, erect hairs. Propodeum with numerous erect hairs on basal and lateral faces, longest exceeding EL. Petiole with numerous shorter erect hairs on sides and crest. Terga with sparse erect discal hairs, progressively longer on succeeding segments, those on first segment about equal to apical thickness of hind tibia. Scape with sparse erect hairs on all except posterior face, and abundant subdecumbent to erect, shorter and finer pubescence. Fore femur with numerous erect hairs on posterior and ventral surfaces, with abundant subdecumbent to erect pubescence on anterior and extensor surfaces; mid and hind femora with mixed decumbent to erect pubescence and pilosity; mid and hind tibiae with abundant mixed decumbent to erect pubescence and pilosity, but mostly appressed on flexor surfaces. Wings without fringe hairs.

Integument: Clypeus slightly shiny, integument roughened between coarse, scattered punctures. Front of head shinier, lightly shagreened, with abundant fine punctures, denser and closer on frontal lobes. Broad median area of scutum lightly shagreened and shiny, with scattered fine punctures; nearer parapsidal lines more coarsely punctate, punctures separated by about twice a puncture diameter; parapsis with punctures a little coarser, subcontiguous. Scutellum sparsely punctate in middle, lightly shagreened and shiny. Pleura duller, closely shagreened and with scattered coarse punctures. First tergum lightly shagreened and moderately shiny at summit, with scattered coarse punctures and more numerous but sparse micropunctures. Second and remaining terga duller, shagreened and densely micropunctate.

Color: Head, appendages and gaster ferruginous; occipital area, narrow apical margins of first four terga and sterna and most of fifth segments, brownish. Thorax blackish brown, with pronotum and scutellum mostly ferruginous and with ferruginous blotches posteromedially on scutum and on pleura and propodeum. Wings clear, subcostal vein dark brownish, remaining veins and stigma light brownish.

Male
Measurements. HL 0.83-0.90 (0.90); HW 0.80-0.87 (0.87); SL 0.97-1.07 (1.00); EL 0.28-0.30 (0.30); WL 2.1-2.5 (2.2); PW 1.3-1.5 (1.4).

Head: A little longer than broad, CI 93-97 (95); distinctly shorter than scape, SI 111-124 (111); in frontal view, sides straight or slightly concave, slightly convergent toward mandibular insertions; occiput broadly convex and with poorly indicated lateral angles. OMD 0.78-0.89 (0.78) x EL; OOD 2.0-3.2 (3.0) x OD; IOD 2.2-3.2 (2.2) x OD. Mandible without preapical notch, cutting margin edentate or with minute denticle near basal angle (one specimen).

Thorax: Robust, PW 0.59-0.67 (0.64) x WL. Propodeum without basal face.

Petiole: Cuneate in profile, apex sharp; in frontal view, crest broadly, angularly incised.

Vestiture: Pubescence scattered on head and thorax, sufficiently dense on first three terga to form sheen.

Cephalic pilosity long, flexuous, about six hairs on each malar area; longest occipital hairs exceeding EL. Mesoscutal hairs numerous, some about equal to EL; scutellum with much sparser, but longer, hairs; pleural hairs sparse, some longer than EL; propodeum with sparse hairs on sides and basal half, shorter than those of pleura. Petiole with short erect hairs on sides and crest. Gaster with sparse long, slender hairs. Front of scape with decumbent to erect hairs; remaining surfaces with decumbent to erect pubescence and scattered hairs. Femora with suberect to erect hairs on all surfaces; tibiae with numerous suberect to erect hairs externally, with scattered suberect to erect hairs and abundant decumbent to suberect pubescence on remaining surfaces. Wings without fringe hairs.

Integument: Head moderately shiny, lightly shagreened, with very sparse micropunctures and scattered coarse punctures. Malar area duller, more coarsely and closely shagreened and with a few very coarse, elongate, setigerous punctures. Occiput duller, with numerous, but still sparse, micropunctures. Mesoscutum moderately shiny, sharply shagreened and with scattered coarse punctures. Scutellum shinier, less sharply shagreened, with scattered coarse punctures. Mesopleura slightly shiny, densely and sharply shagreened, with sparse coarse punctures. Propodeum slightly shiny, uniformly shagreencd, sparsely, coarsely punctate. Summit of first tergum moderately shiny, sparsely micropunctate; second and third terga duller, more distinctly shagreened and closely micropunctate.

Color: Blackish, antennae and legs medium brown. Wings clear, veins and stigma light brownish, subcostal vein darker.



Type Material
Holotype worker, allotype male; one female, 94 worker and five male paratypes: Big Rock Wash, 2770', near Palmdale Blvd., Los Angeles Co., CALIF., 31 Mar. 1972 (I. P. & K. E. Donahue) in. Three worker paratypes in each of the following:, , and private collections of GCW, REG.

Etymology
The specific name is compounded from the first four letters of the names of the collectors of the type series, Katherine and Julian Donahue, to whom this species is dedicated.

References based on Global Ant Biodiversity Informatics

 * Des Lauriers J., and D. Ikeda. 2017. The ants (Hymenoptera: Formicidae) of the San Gabriel Mountains of Southern California, USA with an annotated list. In: Reynolds R. E. (Ed.) Desert Studies Symposium. California State University Desert Studies Consortium, 342 pp. Pages 264-277.
 * Snelling R. R. 1976. A revision of the honey ants, genus Myrmecocystus (Hymenoptera: Formicidae). Natural History Museum of Los Angeles County. Science Bulletin 24: 1-163