Temnothorax politus

Smith (1939) reported: the workers of this ant seem to be most commonly found on the ground in the vicinity of irrigation canals, washes, and rivers. Specimens have been taken at altitudes up to 4,500 feet. They are rather shy and sensitive to heat. Little else is known of their biology except that one nest was found in the bark of a cottonwood tree, about 2 inches above the surface of the soil.

Identification
M. R. Smith (1939) - The worker of this species is characterized by its strongly convex, evenly arched thorax; absence of dorsal thoracic sutures; peculiarly shaped petiole, the peduncle of which is approximately the length of the petiolar node; the smooth and shining surface of the body; and the general black color.

Prebus (2021) - Temnothorax politus can be separated from all other species in the salvini clade by the following character combination: posterior margin of head convex; in profile view, dorsum of mesosoma strongly convex; pronotal declivity not marked by an angle as it transitions from the anterior face of the pronotum to the dorsal face; propodeum not depressed below the level of the promesonotum; propodeal spines longer than the propodeal declivity, directed posterodorsally, and weakly downcurved; hind femora weakly to strongly incrassate; petiolar node node robust and erect, nearly squamiform and dorsally rounded, not leaning posteriorly over the caudal cylinder of the petiole; postpetiole narrow to moderately broad: greater than 1.7 times the width of the caudal cylinder of the petiole; legs and nearly all other surfaces of the body covered in long, tapering, suberect setae; antennal scape moderately long, surpassing the posterior margin of the head by about the maximum width of the antennal scape; integument predominantly dark brown, nearly black.

Similar species: Due to the predominantly smooth and shining sculpture, dark coloration, and long, tapering setae, Temnothorax politus is unlikely to be confused with any other species in the Nearctic. Temnothorax tenuisculptus and less sculptured specimens of Temnothorax subditivus may be confused with T. politus, but both of these have short, blunt setae.

Distribution
Low-to-mid elevations, southern Arizona, U.S.A. & Sonora, Mexico.

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

Biology
Prebus (2021) - Temnothorax politus is known only from the hot deserts and sky islands of southern Arizona and Sonora, Mexico. In desert habitats, it is apparently restricted to washes, irrigation canals, and other riparian habitats (Smith, 1939). In the original description, it was noted that Wesson collected this species at higher elevations in the Santa Catalina Mountains near Tucson, but no habitat data was associated with this occurrence. Smith (1939) also recorded that this species nests under the bark of cottonwood trees near the ground; I have personally collected several nests from ~ 12 cm diameter fallen cottonwood branches in gallery forest, as well as ~ 3 cm diameter hollow twigs in cottonwood leaf litter on the banks of a desert wash. This species is probably active in the nocturnal or crepuscular hours, at least in warm desert habitats: pitfall traps that I left overnight in Cienega Creek Preserve near Vail, Arizona yielded several workers, although I observed none foraging diurnally in the pitfall localities.

Castes
Known only from the worker caste.

Nomenclature

 *  politus. Macromischa polita Smith, M.R. 1939e: 506, pl. 1, fig. B (w.) U.S.A. Combination in Leptothorax: Baroni Urbani, 1978b: 478; in Temnothorax: Bolton, 2003: 272.

Worker
Worker (PI. I, B). Length 2-2.4 mm.

Head, exclusive of mandibles, subrectangular, slightly longer than broad; posterior border faintly convex; occipital angles strongly rounded, and sides moderately convex. Eye convex, removed by at least the length of its greatest diameter from base of mandible. Antenna 12-segmented; scape slender, extending farther posteriorly on head than scape of floridana; first funicular segment approximately length of the three succeeding segments combined, club 3-segmented, as long as remainder of funiculus. Clypeus convex, more strongly projecting than that of subditiva, posterior border rounded and extending well back between frontal carinqe. Frontal area small, triangular, poorly defined. Mandible 5-toothed, the two apical teeth clearly visible. Thorax short, robust, in profile with strongly convex and rather evenly arched dorsum; from above somewhat broader anteriorly than posteriorly, with rounded humeral angles and no promesonotal or mesoepinotal sutures; epinotal spines large, at least twice length of their interbasal space. Femora and tibiae incrassate, especially those of the posterior pair of legs. In profile, petiolar peduncle short, approximately length of bulbous node, which has subvertical anterior and posterior surfaces, and an evenly convex dorsal surface; peduncle with a small ventral footh; from above, petiolar node somewhat campanulate; postpetiole transversely elliptical, approximately one and one-half times as broad as petiolar node. Base of gaster with strong angles.

Head, thorax, petiole, postpetiole, gaster, femora, and tibiae smooth and shining; mandibles longitudinally striate, clypeus with a prominent median carina and several lateral rugulae, cheeks and anterior portion of each frontal carina with longitudinal rugulae, meso- and metapleura of thorax longitudinally rugulose punctate.

Hairs grayish, slender, erect, moderately abundant on all parts of body; shorter and more suberect on appendages.

Black; with lighter mandibles, epinotal spines, coxae, trochanters, bases of femora, tibiae, and tarsi.

Prebus (2021) - (n = 7): SL = 0.424-0.555 (0.503); FRS = 0.170-0.235 (0.210); CW = 0.468-0.655 (0.577); CWb = 0.419-0.602 (0.526); PoOC = 0.201-0.282 (0.255); CL = 0.529-0.715 (0.648); EL = 0.121-0.180 (0.150); EW = 0.102-0.129 (0.116); MD = 0.119-0.208 (0.157); WL = 0.581-0.855 (0.744); SPST = 0.213-0.318 (0.276); MPST = 0.207-0.297 (0.247); PEL = 0.239-0.355 (0.302); NOL = 0.150-0.223 (0.179); NOH = 0.094-0.223 (0.133); PEH = 0.165-0.249 (0.216); PPL = 0.114-0.169 (0.143); PPH = 0.132-0.206 (0.168); PW = 0.282-0.431 (0.371); SBPA = 0.108-0.161 (0.143); SPTI = 0.165-0.267 (0.229); PEW = 0.101-0.163 (0.133); PNW = 0.120-0.185 (0.159); PPW = 0.188-0.286 (0.246); HFL = 0.407-0.579 (0.513); HFWmax = 0.098-0.155 (0.136); HFWmin = 0.028-0.061 (0.046); CS = 0.684-0.960 (0.851); ES = 0.172-0.241 (0.208); SI = 92-101 (96); OI = 23-27 (25); CI = 79-84 (81); WLI = 135-147 (141); SBI = 26-28 (27); PSI = 35-39 (37); PWI = 175-192 (185); PLI = 196-250 (212); NI = 100-171 (141); PNWI = 113-127 (120); NLI = 52-67 (60); FI = 243-350 (302).

In full-face view, head subquadrate, longer than broad (CI 79-84). Mandibles densely, finely striate but shining and armed with five teeth: the apical-most well developed and acute, followed by a less developed preapical tooth and three equally developed smaller teeth. Anterior clypeal margin flat medially. Antennal scapes moderately long: when fully retracted, surpassing the posterior margin of the head capsule by about the maximum width of the antennal scape (SI 92-101). Antennae 12-segmented; antennal club of composed of three segments, with the apical-most segment slightly longer than the preceding two in combination. Frontal carinae moderately long, extending past the antennal toruli by about three and a half times the maximum width of the antennal scape. Compound eyes moderately protruding past the lateral margins of the head capsule. Lateral margin of head weakly convex, forming a continuous arc from the mandibular insertions to the posterior margin of the head. Posterior head margin flat but rounding evenly into the lateral margins.

In profile view, compound eyes ovular and moderately large (OI 23-27), with 12 ommatidia in longest row. Pronotal declivity indistinct, neck and anterior face of pronotum forming a ~120° angle. Mesosoma predominantly evenly convex from where it joins the pronotal neck to the propodeal spines; propodeum very weakly depressed, so that the dorsal margin dips slightly anterior to the base of the propodeal spines. Promesonotal suture extending from the posterior margin of the procoxal insertion only to the mesothoracic spiracle, which is moderately well developed. Metanotal groove visible as a disruption of the sculpture laterally from where it arises between the mid- and hind coxae to where it ends in the poorly developed metathoracic spiracle. Propodeal spiracle moderately well developed, directed posterolaterally, and separated from the propodeal declivity by about four spiracle diameters. Propodeal spines well developed and very long (PSI 35-39), longer than the propodeal declivity, tapering evenly from the base, very weakly downcurved, and acute. Propodeal declivity flat, forming a rounded ~100° angle with the base of the propodeal spines. Propodeal lobes rounded and weakly developed. Metapleural gland bulla small, extending from the metacoxal insertion halfway to the propodeal spiracle. Petiole long (PLI 196-250), without tubercles anterodorsally. Subpetiolar process in the form of a small, acute tooth; ventral margin of petiole nearly flat posterior to it. Petiolar peduncle moderately long: comprising about half of the petiole. Petiolar node robust and erect, nearly squamiform: transition between peduncle and node marked by a rounded angle of ~120°; anterior face forming a rounded ~90° angle with the short, evenly convex dorsal face; dorsal face rounding evenly into the short posterior face, which forms a ~95° angle with the caudal cylinder. Postpetiole evenly rounded anteriorly, flattened dorsally, and weakly lobed ventrally.

In dorsal view, humeri developed: evenly rounded and slightly wider than the rest of the mesosoma; mesothoracic spiracles weakly protruding past the lateral margins of the mesosoma, visible as angles where the pronotum meets the mesonotum. Metanotal groove absent: mesonotum and propodeum completely fused and lateral margins converging evenly to the bases of the propodeal spines. Propodeal spines narrowly approximated basally and diverging apically, their apices separated from each other by slightly less than their length, the negative space between them V shaped. Petiolar peduncle with spiracles weakly protruding past the lateral margins, and slightly broader where they arise. Petiolar node nearly evenly transversely ovular, but slightly flattened posteriorly; node wider than the peduncle and the caudal cylinder. Postpetiole narrow (PWI 175-192) and transversely rectangular, articulating with most of the anterior margin of the gaster. Anterior margin of the postpetiole flat and meets the lateral margins at a rounded ~90° angle; lateral margins parallel to the angulate posterior corners; posterior margin flat. Metafemur moderately to strongly incrassate (FI 243-350).

Sculpture: median clypeal carina present, extending posteriorly to the level of the antennal toruli, and flanked on either side by two equally strong carinae. Lateral clypeal lobes with additional, weaker carinae; ground sculpture smooth and shining. Antennal scapes shining through very weak areolate ground sculpture. Cephalic dorsum predominantly smooth and shining except for piligerous punctures, but with fine costulae flanking the frontal carinae medially, and concentric costulae surrounding the antennal insertions. Lateral surfaces of head with costulae over weak areolate sculpture surrounding the compound eyes and between the eyes and the mandibular insertions. Ventral surface of head smooth and shining except for a narrow strip of areolate sculpture surrounding the median sulcus. Mesosoma with weak areolate sculpture on the pronotal neck. Lateral surface of the pronotum smooth and shining except for fine costulae along the ventral margin. Mesopleuron, metapleuron and anterior half of the lateral surface of propodeum predominantly smooth and shining, but with weak costulae. Propodeal declivity smooth and shining. Dorsal surface of mesosoma predominantly smooth and shining, but with weak costulae on the propodeum leading into the bases of the propodeal spines. Femora smooth and shining. Petiole uniformly smooth and shining. Dorsum of postpetiole smooth and shining, with weak areolate sculpture on the posterior quarter. Gaster smooth and shining, without spectral iridescence.

Setae: antennal scapes and funiculi with short, subdecumbent pilosity. Dorsum of the head, pronotum, waist segments, and gaster with abundant, erect, tapering setae, the longest of which are about the length of the compound eye. The dorsum of the head bears ~82, mesosoma ~84, petiole 12, postpetiole ~26, and first gastral tergite ~140 setae. Short, sparse pubescence absent.

Color: predominantly dark brown, nearly black. The mandibles, propodeal spines, coxae, bases of the femora, tibiae, and tarsi testaceous yellow. The antennae and remainder of the femora testaceous brown.

Queen
Prebus (2021) - (n = 1): SL = 0.620; FRS = 0.294; CW = 0.796; CWb = 0.742; PoOC = 0.316; CL = 0.800; EL = 0.216; EW = 0.175; MD = 0.184; WL = 1.298; SPST = 0.326; MPST = 0.374; PEL = 0.444; NOL = 0.222; NOH = 0.189; PEH = 0.366; PPL = 0.203; PPH = 0.309; PW = 0.761; SBPA = 0.337; SPTI = 0.380; PEW = 0.206; PNW = 0.274; PPW = 0.409; HFL = 0.693; HFWmax = 0.149; HFWmin = 0.057; CS = 1.142; ES = 0.304; SI = 84; OI = 27; CI = 93; WLI = 175; SBI = 45; PSI = 25; PWI = 199; PLI = 219; NI = 117; PNWI = 133; NLI = 50; FI = 261.

In full-face view, head subquadrate, slightly longer than broad (CI 93). Mandibles densely, finely striate but shining and armed with five teeth: the apical-most well developed, followed by a less developed preapical tooth and three equally developed smaller teeth. Anterior clypeal margin emarginated medially. Antennal scapes moderately long: when fully retracted, just reaching the posterior margin of the head capsule (SI 84). Antennae 12-segmented; antennal club composed of three segments, with the apical-most segment as long as the preceding two in combination. Frontal carinae moderately long, extending past the antennal toruli by about two and a half times the maximum width of the antennal scape. Compound eyes moderately protruding past the lateral margins of the head capsule. Lateral margin of head evenly convex, converging from below the compound eyes to the mandibular insertions. Posterior head margin convex, rounding evenly into the lateral margins.

In profile view, compound eyes ovular and large (OI 27), with 16 ommatidia in longest row. Mesoscutum rounded evenly anteriorly, covering the dorsal surface of the pronotum, and flat dorsally. Mesoscutellum slightly higher than the level of the mesoscutum. Posterior margin of metanotum extending past the posterior margin of the mesoscutum. Propodeal spiracle well developed, directed posterolaterally, and separated from the propodeal declivity by about four spiracle diameters. Propodeal spines stout and well developed, but short (PSI 25), about as two thirds as long as the propodeal declivity, tapering evenly from the base, directed posteriorly, slightly downcurved, and acute. Propodeal declivity straight and flat, forming a rounded ~100° angle with the base of the propodeal spines. Propodeal lobes rounded and very weakly developed. Metapleural gland bulla small, extending from the metacoxal insertion halfway to the propodeal spiracle. Petiole long (PLI 219), without tubercles anterodorsally. Subpetiolar process in the form of a small, very acute tooth; ventral margin of petiole nearly flat. Petiolar peduncle moderately long: comprising half the length of the petiole. Petiolar node robust and erect: transition between peduncle and node marked by a rounded angle of ~130°; anterior face forming a rounded ~90° angle with the short, evenly convex dorsal face; dorsal face rounding evenly into the short posterior face, which forms a ~110° angle with the caudal cylinder. Postpetiole evenly rounded anterodorsally, bulging before it transitions into the flattened dorsal face; ventral surface weakly lobed.

In dorsal view, mesoscutum covering pronotum anteriorly, but humeri visible laterally as rounded sclerites. Propodeal spines diverging apically, their apices separated from each other by about two times their length. Petiolar peduncle with spiracles protruding past the lateral margins, the peduncle broadened where they arise. Petiolar node transversely ovular. Petiolar node wider than the peduncle, and evenly grading into the caudal cylinder, which is slightly narrower than the node. Postpetiole narrow (PWI 199) and transversely rectangular, articulating with most of the anterior margin of the gaster, leaving angulate margins on each side exposed. Anterior margin of postpetiole very weakly convex, nearly convex with corners marked by rounded angles as it transitions to the lateral margins, which are parallel to the angulate posterior corners; posterior margin flat. Metafemur moderately incrassate (FI 261).

Sculpture: median clypeal carina present, extending from the anterior margin nearly to the level of the antennal toruli; lateral margins of median clypeal lobe with two carinae that are slightly weaker than the medial carina. Lateral clypeal lobes with additional weaker carinae; ground sculpture weakly areolate. Antennal scapes shining through weak areolate sculpture. Cephalic dorsum rugose-costate, over weak areolate ground sculpture; concentric costulae surrounding the antennal insertions. Lateral surfaces of head sculptured similarly to the dorsum of the head. Ventral surface of head with rugulae over very weak areolate ground sculpture. Pronotal neck areolate. Pronotum with costulae, becoming very weak medially. Anepisternum and katepisternum smooth and shining medially, but with weak costulae along the margins of the sclerites. Metapleuron and lateral face of the propodeum costate. Area between the propodeal spiracle and base of propodeal spines, as well as the propodeal declivity, smooth and shining. Propodeal declivity weakly areolate. Mesoscutum costulate, with smooth and shining patches laterally. Mesoscutellum smooth and shining medially, surrounded by weak costulae and areolae laterally. Femora shining, with traces of weak areolate sculpture. Petiole with very fine areolate sculpture ventrolaterally, around the base of the petiolar node. Longitudinal carina running from the petiolar spiracle to the caudal cylinder. Dorsal surface of the node with weak costulae. Dorsum of postpetiole weakly areolate anteriorly, posterior margin weakly strigulate. Sclerites of the gaster shining but dulled by very fine areolae, as found on the ventrolateral surface of the petiole. Spectral iridescence absent.

Setae: antennal scapes and funiculi with short, subdecumbent pilosity. Dorsum of the head, pronotum, waist segments, and gaster with abundant, erect, tapering setae, the longest of which are about the width of the compound eye. Short, sparse pubescence absent.

Color: predominantly dark brown, nearly black. The mandibles, propodeal spines, coxae, bases of the femora, tibiae, and tarsi testaceous yellow. The antennae and remainder of the femora testaceous brown.

Type Material
Tucson area, Phoenix, Florence, Arizona. Cotypes.-No.'53249,. Described from 26 specimens, collected by Robert G. Wesson. All these are in the United States National Museum collection except the following: 2 workers from Phoenix, Robert G. Wesson; 2 workers from along Santa Cruz River, ; 2 workers from along Santa Cruz River,.

Prebus (2021) - The type series consisted of multiple localities across Arizona. A specimen from the Santa Cruz river near Tucson is designated to be the lectotype, which leaves the remainder of the type series as paralectotypes.

Syntype workers. Arizona, U.S.A. One syntype worker here designated lectotype.

Lectotype: worker, U.S.A.: Arizona: 6.5 km up Santa Cruz River from Tucson, 13 September 1938, R.G. Wesson, M.C.Z. cotype 23781 (MCZENT00023781, top specimen on pin).

Paralectotype workers: same pin as lectotype, 1 worker (MCZENT00023781, bottom specimen on pin); Sabino Canyon, 8 October 1938, 945 m, R. G. Wesson #I03 I, 1 worker (No. 53249 U.S. N.M. Cotype, USNMENT00528925) 1 worker (No. 53249 U.S.N.M. Cotype, USNMENT00922558) [USNM] 1 worker (CASENT0105625) [USNM]; W of Baboquivari Peak, 50 km E of Sells, 25 September 1938 1,070-1,220 m, R.G. Wesson #I30k, 1 worker (No. 53249 U.S. N.M. Cotype, USNMENT00922559) [USNM]; Catalina Mountains, 11 September 1938, 1,370 m, R.G. Wesson #24j, 2 workers (No. 53249 U.S. N.M. Cotype, LACMENT323200).

Etymology
Prebus (2021) - Morphological, from the Latin ʻpolitus' (= polished), in reference to the smooth and shining integument of this species.

References based on Global Ant Biodiversity Informatics

 * Baroni Urbani C. 1978. Materiali per una revisione dei Leptothorax neotropicali appartenenti al sottogenere Macromischa Roger, n. comb. (Hymenoptera: Formicidae). Entomol. Basil. 3: 395-618.
 * Johnson R. Personnal Database. Accessed on February 5th 2014 at http://www.asu.edu/clas/sirgtools/resources.htm
 * Smith M. R. 1939. Ants of the genus Macromischa Roger in the United States (Hymenoptera: Formicidae). Annals of the Entomological Society of America 32: 502-509.
 * Vásquez-Bolaños M. 2011. Lista de especies de hormigas (Hymenoptera: Formicidae) para México. Dugesiana 18: 95-133