Temnothorax terrigena

Mackay (2000) "This species nests in and on the ground and under stones. It is reasonably common in Austin (Feener, 1981) and in the Chisos Mountains of southwestern TX in pinyons, desert canyons and high forests (Van Pelt, 1983)."

Identification
Prebus (2021) - Prebus (2021) – The lone member of the terrigena group of the Temnothorax salvini clade. Temnothorax terrigena can be separated from all other species in the salvini clade by the following character combination: in profile view, dorsum of mesosoma weakly convex; metanotal groove not impressed; propodeum not depressed below the level of the promesonotum; propodeal spines shorter than the propodeal declivity and directed posterodorsally; hind femora weakly to moderately incrassate; petiolar node subquadrate, not leaning posteriorly, and rounded dorsally; petiolar node as long as, or only slightly longer than high; posterior face of petiolar node about the same height as the anterior face; postpetiole moderately broad, greater than 1.5 times the width of the caudal cylinder of the petiole, but less than 2.2 times; setae on head, mesosoma, waist segments and gaster erect, short, sparse and blunt (never long and tapering); integument predominantly yellow.

Similar species: Temnothorax andrei, Temnothorax carinatus, Temnothorax goniops, Temnothorax pilicornis, Temnothorax rugosus, Temnothorax subditivus (light form), Temnothorax torrei. Temnothorax terrigena differs from T. pilicornis by the pilosity on the antennal scapes and the shape of the petiolar node: the scape setae are subdecumbent and the posterior face of the petiolar node is much shorter than the anterior face in T. pilicornis The pedunculate petiole with an erect subquadrate node will separate T. terrigena from T. subditivus, which has a squamiform petiolar node. Temnothorax rugosus has a cuneiform to subcuneiform petiolar node, as opposed to the erect and compact petiolar node of T. terrigena. Temnothorax terrigena differs from T. torrei by the presence of four erect setae on the dorsum of the petiolar node, as opposed to two. Temnothorax terrigena can be distinguished from T. goniops by the relatively short propodeal spines, which are shorter than the propodeal declivity (longer than the declivity in T. goniops). Temnothorax andrei has a relatively narrow postpetiole, and both T. andrei and T. carinatus differ from T. terrigena by their head sculpture, which typically has a medial strip of smooth and shining sculpture, as opposed to the uniformly areolate head of T. terrigena.

Mackay (2000) - A member of the Temnothorax andrei species complex. The workers of this species have a 12-segmented antenna, and are small (total length 1.5mm), yellow ants with black eyes. The maximum diameter of the eye is less than the distance from the anterior border of the eye to the anterior edge of the head near the insertion of the antennae. The propodeal spines are small and the node of the petiole is rounded. The subpeduncular process is small and weakly developed. The postpetiole is massive with the node being nearly twice as wide as the node of the petiole. The petiolar node is somewhat truncate in profile with the anterior and posterior faces being almost parallel. The entire dorsum of the head is densely and evenly punctate, the punctures lining up into poorly defined rows. The dorsum and side of the mesosoma, as well as the petiole and postpetiole, are densely and evenly punctate, similar to the sculpture of the head. The gaster is smooth and glossy.

This is an easily recognized species. Its light yellow color and very finely, but distinctly and completely punctate head separate it from most other species in the genus. The mesosoma is punctate in a similar manner, although the punctures are somewhat coarser. The heavily and densely punctate head would separate this species from most other species, including Temnothorax furunculus and Temnothorax andrei The relatively small eyes (maximum diameter about equal to distance between anterior margin of eye and base of mandible) would separate it from Temnothorax bestelmeyeri. This species can be distinguished from the similar Temnothorax andersoni by the smooth and glossy dorsum of the gaster.

Distribution
Low elevations, Texas, U.S.A. to Tamaulipas, Mexico; from the Chisos Mountains in SW Texas, through central Texas, and south to Tamaulipas state in Mexico.

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

Habitat
Apparently inhabits a broad range of habitats, including pinyon forests, desert canyons, high Douglas fir/pine forests, and semiarid plains (van Pelt, 1983, Wheeler, 1903a).

Abundance
Common in some areas within its range.

Biology
Prebus (2021) - Temnothorax terrigena is common in the type locality of Austin, Texas, where it has been collected in litter samples at the Brackenridge Field Laboratory (Feener, 1981). In the original description (Wheeler, 1903b), T. terrigena was noted as nesting under stones in black clay soil. Wheeler (1903b) observed workers foraging diurnally and that this species may possibly be pleisiobiotic with other myrmicines: Wheeler collected a nest from a midden pile of the fungus farming ant Mycetomoellerius turrifex, and another from a Pheidole tepicana colony.

Wheeler (1903) - This small species lives in and on the ground. At Austin I have occasionally seen a few workers running about on the dry gravelly hill-slopes exposed to the sun. At McNeil I took a few dozen workers and a dealated queen, which were inhabiting a small spherical chamber.

Nests in soil, under rocks and in cavities in objects on the ground.

Nomenclature

 *  terrigena. Leptothorax terrigena Wheeler, W.M. 1903c: 254, pl. 12, fig. 21 (w.q.) U.S.A. Combination in L. (Myrafant): Smith, D.R. 1979: 1395; in Temnothorax: Bolton, 2003: 272. See also: Mackay, 2000: 414.

Worker
Length 1.5-1.75 mm. Head rather narrow, with parallel sides. Mandibles 5-toothed. Clypeus moderately convex, without median impression and with broadly rounded, non-sinuate anterior border. Antennal 12-jointed, scape extending to j the distance between the eye and the posterior corner of the head; first funicular joint as long as the three succeeding joints together; joints 2-8 of funiculus decidedly broader than long, subequal; three terminal joints forming a distinct club, of which the two basal joints are subequal in length but not in thickness, arid together shorter than the terminal joint. Thorax slender, somewhat broader in front than behind, with rounded humeral angles and moderately elevated anterior pronotal border. Pleurae compressed; dorsum flattened and without mesoepinotal constrictions. Epinotal spines small, conical, distinctly longer and further apart than broad at their bases. Petiole short, hardly It times as long as broad, sides of node convex when seen from above and much broader than the peduncle; in profile the node is high and very thick with an evenly rounded summit, very steep and concave anterior, and very abrupt posterior declivity; ventral tooth rather large, blunt. Postpetiole twice as broad as the petiole, distinctly broader than long, transversely elliptical from above, with rounded anterior angles. Gaster of the usual shape.

Mandibles and clypeus subopaque, the former longitudinally striated and with a few coarse punctures, the latter longitudinally rugose. Head opaque throughout, evenly and densely punctate except along the sides of the frontal region, where there are a few delicate longitudinal rugae. Thorax, petiole and postpetiole opaque, densely punctate. Gaster smooth and shining.

Hairs white, moderately numerous, clavate on66 crown of head, thorax and abdomen; erect on head and thorax, more reclinate on the pedicel and gaster; minute, inconspicuous and appressed on the antennre and legs.

Whole body, even the anterior portion of the gaster, golden-yellow, except the antennal club which is blackened.

Prebus (2021) - (n = 14): SL = 0.349-0.403 (0.378); FRS = 0.133-0.165 (0.152); CW = 0.425-0.482 (0.456); CWb = 0.395-0.457 (0.423); PoOC = 0.208-0.233 (0.219); CL = 0.511-0.561 (0.536); EL = 0.102-0.131 (0.117); EW = 0.080-0.101 (0.089); MD = 0.104-0.123 (0.112); WL = 0.539-0.634 (0.586); SPST = 0.128-0.163 (0.143); MPST = 0.177-0.222 (0.194); PEL = 0.211-0.265 (0.228); NOL = 0.101-0.134 (0.118); NOH = 0.080-0.110 (0.100); PEH = 0.159-0.224 (0.198); PPL = 0.140-0.180 (0.156); PW = 0.274-0.314 (0.298); SBPA = 0.127-0.154 (0.141); SPTI = 0.140-0.180 (0.165); PEW = 0.113-0.146 (0.130); PNW = 0.134-0.171 (0.154); PPW = 0.237-0.284 (0.256); HFL = 0.311-0.405 (0.362); HFWmax = 0.102-0.129 (0.116); HFWmin = 0.038-0.050 (0.044); CS = 0.651-0.738 (0.691); ES = 0.142-0.178 (0.161); SI = 83-93 (89); OI = 21-26 (23); CI = 76-82 (79); WLI = 135-143 (138); SBI = 30-36 (33); PSI = 21-28 (24); PWI = 180-215 (198); PLI = 123-161 (147); NI = 98-148 (118); PNWI = 106-134 (119); NLI = 43-61 (52); FI = 225-300 (268).

In full-face view, head subquadrate and elongate (CI 76-82). Mandibles densely 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 strongly convex medially. Antennal scapes short: when fully retracted, failing to reach the posterior margin of the head capsule by about two times the maximum width of the scape (SI 83-93). Antennae 12-segmented; antennal club of composed of three segments, with the apical-most segment about twice as long as the preceding two in combination. Frontal carinae short, extending past the antennal toruli by about one 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 very weakly convex, nearly flat, forming a continuous arc from the mandibular insertions to the posterior margin of the head. Posterior head margin concave medially but rounding evenly into the lateral margins.

In profile view, compound eyes ovular and moderately large (OI 21-26), with 8 ommatidia in longest row. Pronotal declivity distinct: neck and anterior face of pronotum forming a ~110° angle; anterior face and dorsum of mesosoma forming a ~120° angle. Mesosoma very weakly convex from where it joins the pronotal neck to 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, which is nearly indistinguishable against the ground sculpture. Propodeal spiracle weakly developed, directed posterolaterally, and separated from the propodeal declivity by about four spiracle diameters. Propodeal spines weakly developed and short (PSI 21-28), about half as long as the propodeal declivity, flared at the base, triangular, and acute. Propodeal declivity flat, forming a rounded ~120° angle with the base of the propodeal spines. Propodeal lobes rounded and weakly developed. Metapleural gland bulla moderately large, extending from the metacoxal insertion two thirds of the way to the propodeal spiracle. Petiole short (PLI 123-161), without tubercles anterodorsally. Subpetiolar process in the form of a moderately large, blunt, triangular tooth which grades evenly into the ventral margin of the petiole posteriorly; ventral margin of petiole flat posterior to it. Petiolar peduncle short: comprising about a third of the total petiole length. Petiolar node robust, erect, and rounded-subquadrate: transition between peduncle and node marked by a rounded angle of ~120°; anterior face forming a ~100° angle with the dorsal face, which is convex; dorsal face meeting the posterior face at a rounded ~90° angle; posterior face forms a ~90° angle with the caudal cylinder. Postpetiole strongly convex anteriorly, weakly convex dorsally, and weakly lobed ventrally.

In dorsal view, humeri developed and distinct: wider than the rest of the mesosoma; mesothoracic spiracles weakly protruding past the lateral margins of the mesosoma, visible as slight 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 broadly approximated basally and diverging apically, their apices separated from each other by about twice their length, the negative space between them "U" shaped. Petiolar peduncle with spiracles weakly protruding past the lateral margins, but not noticeably constricted anterior to them. Petiolar node campaniform and antero-posteriorly compressed: convex anteriorly and flat posteriorly; node slightly wider than the peduncle and caudal cylinder. Postpetiole moderately broad (PWI 180-215) and subtrapezoidal, articulating with the nearly the entire anterior margin of the gaster, but leaving small angles on either side exposed. Anterior margin of the postpetiole weakly convex and evenly rounds into the lateral margins; lateral margins converge slightly to the rounded posterior corners; posterior margin broadly concave. Metafemur weakly to moderately incrassate (FI 225-300).

Sculpture: median clypeal carina present but weak, extending posteriorly nearly to the frontal triangle, and flanked on either side by two equally strong carinae. Lateral clypeal lobes with additional, weaker carinae; ground sculpture weakly areolate. Antennal scapes weakly areolate. Cephalic dorsum and lateral surfaces of head uniformly areolate. Ventral surface of head shining through weak areolae. Pronotal neck and anterior face of the pronotum areolate. Lateral surfaces of mesosoma and shining through weak areolate sculpture. Propodeal declivity areolate. Dorsal surface of mesosoma uniformly areolate. Femora shining, with traces of weak areolate sculpture. Petiole and postpetiole areolate, with anterior and dorsal surfaces of petiolar node, and dorso-medial surface of postpetiole smooth and shining. First gastral tergite and sternite smooth and shining, without spectral iridescence.

Setae: antennal scapes and funiculi with short, adpressed pilosity. Dorsum of the head, pronotum, waist segments, and gaster with sparse, erect, blunt-tipped, nearly clavate setae, the longest of which are about the half the width of the compound eye. The head bears ~28, mesosoma ~16, petiole 6, postpetiole ~10, and first gastral tergite ~36 setae. Short, sparse pubescence present over the entire body, but difficult to detect against the lightly colored integument.

Color: predominantly yellow, with masticatory margin of mandibles dark brown; antennal club testaceous yellow.

Queen
(dealated) Length 2.5 mm.

Head opaque, densely punctate; cheeks and whole preocellar region irregularly longitudinally rugulose, the postocellar region and posterior angles more reticulate. Thorax opaque, densely punctate; mesonotum and scutellum with very faint, parallel, longitudinal rugae. Epinotal spines very short and stout, regularly conical, not as far apart as they are broad at the base. Petiole and postpetiole like those of the worker, but the latter segment fully twice as broad as long. Both segments of the pedicel densely punctate, opaque, except the dorsal surfaces of the nodes which are somewhat smooth and shining. Body brownish yellow, legs pale-yellow. Antennal club, wing-insertions, sides and posterior border of first gastric segment, a broad transverse band on the second gastric segment and the tip of the gaster, dark-brown. Pilosity like that of the worker.

Prebus (2021) - (n = 2): SL = 0.437; FRS = 0.190-0.202 (0.196); CW = 0.596-0.605 (0.601); CWb = 0.541-0.554 (0.548); PoOC = 0.214-0.221 (0.218); CL = 0.599-0.613 (0.606); EL = 0.189-0.209 (0.199); EW = 0.154; MD = 0.108-0.112 (0.110); WL = 0.969-0.989 (0.979); SPST = 0.191-0.207 (0.199); MPST = 0.249-0.266 (0.258); PEL = 0.310-0.319 (0.315); NOL = 0.152-0.165 (0.159); NOH = 0.115-0.133 (0.124); PEH = 0.247-0.268 (0.258); PPL = 0.163-0.211 (0.187); PW = 0.575-0.601 (0.588); SBPA = 0.288-0.306 (0.297); SPTI = 0.257-0.268 (0.263); PEW = 0.161-0.202 (0.182); PNW = 0.216-0.217 (0.217); PPW = 0.339-0.346 (0.343); HFL = 0.466-0.482 (0.474); HFWmax = 0.099-0.124 (0.112); HFWmin = 0.043-0.044 (0.044); CS = 0.841-0.861 (0.851); ES = 0.266-0.286 (0.276); SI = 79-81 (80); OI = 32-33 (32); CI = 90; WLI = 179; SBI = 53-55 (54); PSI = 19-21 (20); PWI = 168-215 (191); PLI = 147-196 (171); NI = 124-132 (128); PNWI = 107-135 (121); NLI = 49-52 (50); FI = 230-282 (256).

In full-face view, head subquadrate, slightly longer than broad (CI 90). 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 strongly convex medially. Antennal scapes short: when fully retracted, failing to reach the posterior margin of the head capsule by about twice the maximum scape width (SI 79-81). Antennae 12-segmented; antennal club composed of three segments, with the apical-most segment about twice as long as the preceding two in combination. Frontal carinae short, extending past the antennal toruli by about 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 flat, rounding evenly into the lateral margins.

In profile view, compound eyes ovular and large (OI 32-33), with 16 ommatidia in longest row. Mesoscutum rounded evenly anteriorly, covering the dorsal surface of the pronotum, and flat dorsally. Mesoscutellum on the same plane as the mesoscutum. Posterior margin of metanotum extending past the posterior margin of the mesoscutum. Propodeal spiracle moderately well developed, directed posterolaterally, and separated from the propodeal declivity by about four spiracle diameters. Propodeal spines stout and moderately well developed, but short (PSI ~ 20), about a third as long as the propodeal declivity, flared at the base, triangular, and acute. Propodeal declivity straight and flat, forming a ~120° 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 moderately long (PLI 147-196), without tubercles anterodorsally. Subpetiolar process in the form of a moderately large, triangular, blunt tooth, which grades evenly into the ventral margin of the petiole posteriorly. Petiolar peduncle moderately long: comprising about half of the total petiole length. Petiolar node erect and squamiform: transition between peduncle and node a rounded ~130° angle; anterior face forming a ~90° angle with the brief dorsal face; dorsal face meeting the posterior face at a ~90° angle; posterior face forms a ~90° angle with the caudal cylinder. Postpetiole flat anteriorly, bulging slightly anterodorsally, flattened posterodorsally; ventral surface weakly lobed.

In dorsal view, mesoscutum covering pronotum anteriorly, but humeri visible laterally as angulate sclerites. Propodeal spines parallel apically, their apices separated from each other by about three times their length. Petiolar peduncle with spiracles weakly protruding past the lateral margins. Petiolar node transversely campaniform: rounded anteriorly and flattened posteriorly; subquadrate when viewed posterodorsally, the dorsum of the node weakly convex. Petiolar node slightly broader than the peduncle and caudal cylinder. Postpetiole moderately broad (PWI 168-215), anteroposteriorly compressed, and subtrapezoidal, articulating with most of the anterior margin of the gaster, leaving small, angulate margins on each side exposed. Anterior margin of postpetiole flat, with corners marked by rounded angles as it transitions to the lateral margins, which converge slightly to the angulate posterior corners; posterior margin flat. Metafemur weakly to moderately incrassate (FI 230-282).

Sculpture: median clypeal carina present, extending from the anterior margin nearly to frontal triangle, and flanked by two weaker, indistinct carinae. Lateral clypeal lobes with additional weaker carinae; ground sculpture weakly areolate. Antennal scapes weakly areolate. Cephalic dorsum areolate, with weak costulae overlying the ground sculpture. Lateral surfaces of head areolate, with fine costulae between the compound eye and mandibular insertion. Ventral surface of head smooth and shining, with weak costulae. Pronotal neck and anterior face of pronotum areolate. Pronotum with areolate ground sculpture arranged into longitudinal rows by superficial costulae. Katepisternum shining medially, otherwise weakly areolate. Anepisternum areolate. Metapleurae and lateral face of propodeum areolate, with costulae that become stronger over the metapleural gland bulla. Propodeal declivity areolate. Mesoscutum predominantly with costulae over areolate ground sculpture; a patch of smooth and shining sculpture anteromedially. Mesoscutellum with costulae over areolate ground sculpture. Femora shining, with traces of weak areolate sculpture. Petiole and postpetiole uniformly areolate, but sculpture becomes weaker on the anterior face of the petiolar node and anterior face of postpetiole. First gastral tergite and sternite smooth and shining, without spectral iridescence.

Setae: antennal scapes and funiculi with short, adpressed pilosity. Dorsum of the head, pronotum, waist segments, and gaster with sparse, erect, blunt-tipped, nearly clavate setae, the longest of which are about a third of the width of the compound eye. Short, sparse pubescence present over the entire body, but difficult to detect against the lightly colored integument.

Color: predominantly yellow; with antennae, dorsomedial surface of head, posteromedial surface of mesoscutum, metanotum, propodeal declivity, caudal cylinder of the petiole, caudal cylinder of the postpetiole, and distal quarters of the gastral sclerites testaceous yellow. Wing bases and masticatory margin of mandibles dark brown.

Type Material
Prebus (2021) - Syntype workers and dealate gyne: McNeil, Texas, U.S.A. One syntype worker here designated lectotype.

Lectotype worker: U.S.A.: Texas: Travis County, McNeil, 22 February 1902, co-type A.M. N.H., bottom specimen on pin (M.C.Z. Type 21038, MCZENT00522078).

Paralectotype workers and gyne: same pin as lectotype, 1 dealate gyne, 1 worker (top and middle specimens on pin) [MCZC]; same data as lectotype, 4 workers (M.C.Z. Type 21038, MCZENT00031038) [MCZC] 3 workers (LACMENT181910) 3 workers (M.C.Z. Type 21038, USNMENT00528965)  3 workers (CASENT0105624) [USNM].

Etymology
Prebus (2021) - Behavioural, from the Latin ʻterra' (= earth) + ʻgenus' (= born), presumably a reference to the terrestrial nesting and foraging habits of this species.

Determination Clarifications
Prebus (2021) - The references to T. terrigena from Hidalgo state by Hernández & Castaño-Meneses (2010), Hernández (2013), Vásquez-Bolaños (2015) are incorrect: the exemplar specimen from the study by Hernández & Castaño-Meneses deposited in the collection proved to be an undescribed species of the tricarinatus species group (sensu Mackay, 2000) upon examination.

References based on Global Ant Biodiversity Informatics

 * Dattilo W. et al. 2019. MEXICO ANTS: incidence and abundance along the Nearctic-Neotropical interface. Ecology https://doi.org/10.1002/ecy.2944
 * Hernandez, F. Varela and G. Castano-Meneses. 2010. Checklist, Biological Notes and Distribution of Ants (Hymenoptera: Formicidae) from Barranca de Metztitlán Biosphere Reserve, Hidalgo, Mexico. Sociobiology 56(2):397-434
 * Mackay W. P. 2000. A review of the New World ants of the subgenus Myrafant, (genus Leptothorax) (Hymenoptera: Formicidae). Sociobiology 36: 265-444.
 * O'Keefe S. T., J. L. Cook, T. Dudek, D. F. Wunneburger, M. D. Guzman, R. N. Coulson, and S. B. Vinson. 2000. The Distribution of Texas Ants. The Southwestern Entomologist 22: 1-92.
 * Smith M. R. 1936. A list of the ants of Texas. Journal of the New York Entomological Society 44: 155-170.
 * Van Pelt, A. 1983. Ants of the Chisos Mountains, Texas (Hymenoptera: Formicidae) . Southwestern Naturalist 28:137-142.
 * Varela-Hernandez, F., M. Rocha-Ortega, W. P. MacKay, and R. W. Jones. 2016. Lista preliminar de las hormigas (Hymenoptera: Formicidae) del estado de Queretaro, Mexico. Pages 429-435 in . W. Jones., and V. Serrano-Cardenas, editors. Historia Natural de Queretaro. Universidad Autonoma de Queretaro, Mexico.
 * Vasquez-Bolanos M. 2011. Checklist of the ants (Hymenoptera: Formicidae) from Mexico. Dugesiana 18(1): 95-133.
 * Vásquez-Bolaños M. 2011. Lista de especies de hormigas (Hymenoptera: Formicidae) para México. Dugesiana 18: 95-133
 * Wheeler W. M. 1903. A revision of the North American ants of the genus Leptothorax Mayr. Proceedings of the Academy of Natural Sciences of Philadelphia. 55: 215-260.
 * Wheeler, G.C. and J. Wheeler. 1985. A checklist of Texas ants. Prairie Naturalist 17:49-64.