Taxonomic revision of the Temnothorax salvini clade (Hymenoptera: Formicidae), with a key to the clades of New World Temnothorax Author Prebus, Matthew M. School of Life Sciences, Arizona State University, Tempe, Arizona, United States & Department of Entomology & Nematology, University of California, Davis, Davis, California, United States mprebus@gmail.com text PeerJ 2021 e 11514 2021-06-30 9 1 462 http://dx.doi.org/10.7717/peerj.11514 journal article 5464 10.7717/peerj.11514 e56413f9-7dc9-4ebc-9085-008cb38b4dc1 2167-8359 PMC8254503 34249486 5102026 Temnothorax aztecoides sp. nov. Distribution: Fig. 153A ; worker, gyne & male: Fig. 154 . Temnothorax salvini grp 3 Prebus , 2021 : 12 . In phylogeny . Type material examined: Holotype worker : MEXICO : Veracruz : Ruiz Cortinez , 13 km NE San Andrés Tuxtla , 18.53235 ° N 95.14477 ° W ± 20 m , 1,080 m ± 5 m , 2 June 2016 , M.M. Prebus #MMP02634, montane rainforest, ex hollow twig hanging from tree ( CASENT0758791 ) [ CASC ]. Figure 154 Temnothorax aztecoides sp. nov. (A–C) Holotype worker (CASENT0758791). (A) Full-face view. (B) Profile view. (C) Dorsal view. (D–F) Paratype gyne (CASENT0758789). (D) Full-face view. (E) Profile view. (F) Dorsal view. (G) Wings. (H–K) Paratype male (CASENT0758790). (H) Full-face view. (I) Profile view. (J) Dorsal view. (K) Wings. Scale bars 0.2 mm. Full-size DOI: 10.7717/peerj.11514/fig-154 Paratype workers, males, and gynes: same data as holotype, 1 worker (CASENT0758792) [ CASC ] 1 dealate gyne (CASENT0758789) [ CASC ] 1 male (CASENT0758790) [ CASC ] 1 alate gyne (CASENT0869605) [ CASC ] 1 alate gyne (CASENT0869606) [ USNM ] 1 alate gyne (CASENT0869607) [ MCZC ] 1 alate gyne (CASENT0869608) [ LACM ] 1 alate gyne (CASENT0869609) [ UCDC ] 1 male (CASENT0869610) [ USNM ] 1 male (CASENT0869611) [ UCDC ] 1 male (CASENT0869612) [ MCZC ] 1 male (CASENT0869613) [ LACM ] 1 worker (CASENT0869614) [ USNM ] 1 worker (CASENT0869615) [ UNAM ] 1 worker (CASENT0869616) [ MCZC ] 1 worker (CASENT0869617) [ LACM ] 1 worker (CASENT0869618) [ UCDC ] 1 worker (CASENT0869619) [ UVGC ] 1 worker (CASENT0869620) [ MCZC ] 1 worker (CASENT0869621) [ AMNH ] 1 worker (CASENT0869622) [ UNAM ] 1 worker (CASENT0869623) [ USNM ] 1 worker (CASENT0869624) [ LACM ] 1 worker (CASENT0869625) [ AMNH ] 1 worker (CASENT0869626) [ FSCA ] . Non-type material examined: MEXICO : Oaxaca : 13 km S Valle Nacional, 17.65947 ° N 96.33438 ° W ± 20 m , 1,340 m ± 5 m , 15 August 2014 , M.M. Prebus#01593, wet broadleaf forest, nest in dead hollow vine, 1 dealate gyne (CASENT0733317) [ UCDC ] 1 worker (CASENT0733318) [ UCDC ] 1 worker (CASENT0733319) [ UCDC ]; Veracruz : 10 km NNE San Andrés Tuxtla, 18.53514 ° N 95.19022 ° W ± 8 m , 1,030 m , 5 June 2016 , P.S. Ward#PSW17623, montane rainforest, ex dead twig of Bursera , ca. 2.5 m above ground, 1w (CASENT0642924) [ UCDC ]; same data as previous, except: 18.53613 ° N 95.19097 ° W ± 13 m , 1,015 m ± 5 m , 5 June 2016 , M.M. Prebus#MMP02692, montane rainforest, ex dead vine hanging from tree, 1 alate gyne, 59 workers (CASENT0757622) [ MMPC ]; 12 km NE San Andrés Tuxtla, 18.53438 ° N 95.1497 ° W ± 250 m , 1,130 m ± 50 m , 4 June 2016 , ADMAC#Go-F-02-1-01, montane wet forest, beating vegetation, 1 worker (CASENT0640387) [ JTLC ] 1 worker (CASENT0640716) [ UCDC ]; same data as previous, except: 18.55793 ° N 95.19018 ° W ± 7 m , 1,495 m ± 5 m , 6 June 2016 , M.M. Prebus#MMP02713, montane rainforest, ex dead stick, 1 alate gyne, 30 workers (CASENT0757637) [ MMPC ]; Ruiz Cortínez, 13 km NE San Andrés Tuxtla, 18.53443 ° N 95.14966 ° W ± 20 m , 1,115 m ± 5 m , 2 June 2016 , M.M. Prebus#MMP02638, montane rainforest, ex hollow twig on live tree, 1 dealate gyne (CASENT0757144) [ MCZC ]; same data as previous, except: 18.53245 ° N 95.14465 ° W ± 10 m , 1,080 m ± 5 m , 2 June 2016 , M.M. Prebus#MMP02633, montane rainforest, stray on low vegetation, 1 worker (CASENT0757137) [ USNM ]; same data as previous, except: 18.53450 ° N 95.14944 ° W ± 15 m , 1,115 m ± 5 m , 2 June 2016 , M.M. Prebus#MMP02640, montane rainforest, ex dead vine, 1 alate gyne, 14 workers (CASENT0757571) [ MMPC ]; same data as previous, except: 18.53434 ° N 95.13850 ° W ± 100 m , 1,040 m ± 5 m ,, 23June 2016 , M.M. Prebus#MMP02647, montane rainforest, ex dead vine, 29 workers (CASENT0757579) [ MMPC ]; same data as previous, except: M.M. Prebus#MMP02648, montane rainforest edge, ex dead vine, 37 workers (CASENT0757580) [ MMPC ]; same data as previous, except: M.M. Prebus#MMP02649, montane rainforest edge, ex dead vine, 1 worker (CASENT0758684) [ UCDC ] 1 worker (CASENT0758785) [ UNAM ]; same data as previous, except: M.M. Prebus#MMP02659, montane rainforest edge, ex dead stick hanging from vine, 13 workers (CASENT0757591) [ MMPC ]; same data as previous, except: M.M. Prebus#MMP02660, montane rainforest edge, ex dead stick hanging from vine, 11 males , 60 workers (CASENT0757592) [ MMPC ]; same data as previous, except: 18.53469 ° N 95.13954 ° W ± 10 m , 1,065 m ± 5 m , 4 June 2016 , M.M. Prebus#MMP02677, montane rainforest, ex dead stick hanging from tree, 1 alate gyne, 77 workers (CASENT0757608) [ MMPC ]; same data as previous, except: 18.53434098 ° N 95.13842097 ° W ± 9 m , 1,070 m ± 5 m , 5 June 2016 , M.M. Prebus#MMP02684, montane rainforest edge, ex dead branch, 1 alate gyne, 2 males , 36 workers (CASENT0757613) [ MMPC ]; same data as previous, except: Prebus#MMP02685, montane rainforest edge, stray worker, 1 worker (CASENT0757615) [ MMPC ]; same data as previous, except: 18.53613 ° N 95.19097 ° W ± 13 m , 1,015 m ± 5 m , 5 June 2016 , M.M. Prebus#MMP02692, montane rainforest, ex dead vine hanging from tree, 1 alate gyne, 59 workers (CASENT0757622) [ MMPC ]; same data as previous, except: 18.53 ° N 95.15 ° W , 1,131 m , 5 June 2016 , K.W. Gray#KWG160605-01, montane rainforest, in log, 6 workers (CASENT0868850-CASENT0868855) [ KWGC ]. Geographic range: Mid elevations in southern Mexico (Los Tuxtlas and the Southern Sierra Madre) ( Fig. 153A ). Worker diagnosis: Temnothorax aztecoides sp. nov. can be separated from all other species in the salvini clade by the following character combination: larger species: WL> 1.25 mm ; dorsum of mesosoma weakly sinuate; metanotal groove not impressed; propodeum not strongly depressed below the level of the promesonotum; propodeal spines present and longer than the propodeal declivity; subpetiolar tooth acutely spiniform and shorter than the setae that arises from the peduncle directly above; petiolar node strongly squamiform: in dorsal view, petiolar node greater than or equal to 1.6 times as broad as caudal cylinder; dorsum of head with predominantly rugose over areolate sculpture; dorsum of petiolar node and postpetiole sculptured; setae on head, mesosoma, legs, waist segments and gaster erect to suberect, long, abundant and tapering; integument predominantly yellow. Similar species: Fellow members of the salvini group. Temnothorax aztecoides sp. nov. can be separated from other members of the salvini group by the strongly squamiform petiolar node (petiolar node less than or equal to 1.5 times as broad as the caudal cylinder in T. longinoi sp. nov. , T. quetzal sp. nov. , T. fortispinosus sp. nov. , T. parvidentatus sp. nov. , and T. salvini ), yellow integument ( T. longinoi sp. nov. , T. longicaulis stat. nov., nom. nov. , T. quetzal sp. nov. , T. fortispinosus sp. nov. , T. parvidentatus sp. nov. , and T. salvini are variously colored, but never uniformly yellow), sculptured dorsum of the petiolar node and postpetiole (smooth in T. aztecus and T. paraztecus sp. nov. ), relatively small subpetiolar tooth (longer than the setae that arises directly above it in T. aztecus and T. paraztecus sp. nov. ), and long propodeal spines (shorter than the propodeal declivity in T. paraztecus sp. nov. ). Worker measurements & indices ( n = 7): SL = 0.849 –0.905 (0.880); FRS = 0.272 –0.305 (0.292); CW = 0.889 –0.973 (0.937); CWb = 0.792 –0.852 (0.822); PoOC = 0.345 –0.395 (0.373); CL = 0.912 –0.980 (0.955); EL = 0.208 –0.240 (0.224); EW = 0.153 –0.171 (0.164); MD = 0.220 –0.268 (0.238); WL = 1.263 –1.388 (1.336); SPST = 0.421 –0.479 (0.458); MPST = 0.338 –0.394 (0.368); PEL = 0.490 –0.580 (0.524); NOL = 0.252 –0.295 (0.284); NOH = 0.149 –0.175 (0.163); PEH = 0.268 –0.309 (0.292); PPL = 0.231 –0.282 (0.251); PW = 0.592 –0.624 (0.610); SBPA = 0.270 –0.307 (0.291); SPTI = 0.326 –0.363 (0.347); PEW = 0.186 –0.213 (0.200); PNW = 0.308 –0.353 (0.331); PPW = 0.316 –0.358 (0.333); HFL = 0.995 –1.065 (1.031); HFWmax = 0.189 –0.224 (0.207); HFWmin = 0.065 –0.077 (0.072); CS = 1.249 –1.342 (1.300); ES = 0.294 –0.324 (0.306); SI = 105–109 (107); OI = 23–24 (24); CI = 85–88 (86); WLI = 158–168 (162); SBI = 34–37 (35); PSI = 33–36 (34); PWI = 160–179 (167); PLI = 191–223 (209); NI = 150–195 (175); PNWI = 157–176 (165); NLI = 49–59 (54); FI = 271–307 (288). Worker description: In full-face view, head subquadrate, longer than broad (CI 85–88). Mandibles 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 weakly convex medially. Antennal scapes very long: when fully retracted, surpassing the posterior margin of the head capsule by about three times the maximum width of the antennal scape (SI 105–09). 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 two times the maximum width of the antennal scape. Compound eyes strongly protruding past the lateral margins of the head capsule. Lateral margin of head 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 23–24), with 17 ommatidia in longest row. Pronotal declivity indistinct, neck and anterior face of pronotum forming a ~120 ° angle. Anterior face of pronotum evenly rounding into dorsal face. Dorsum of mesosoma flat from where it joins the anterior face of the pronotum 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 five spiracle diameters. Propodeal spines well developed and very long (PSI 33–36), longer than the propodeal declivity, tapering evenly from the base, acute, and straight but slightly upturned at the apices. Propodeal declivity weakly concave, 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 long (PLI 191–223), without tubercles anterodorsally. Subpetiolar process in the form of a small, spiniform, acute, anteriorly curved tooth; ventral margin of petiole weakly concave posterior to it but bulging slightly medially. Petiolar peduncle very long: comprising about two thirds of the total petiole length. Petiolar node rounded-squamiform: transition between peduncle and node marked by a rounded angle of ~120 ° ; anterior face rounding evenly into the posterior face, the dorsal margin evenly convex; posterior face forms a ~100 ° angle with the caudal cylinder. Postpetiole evenly rounded anterodorsally, bulging before flattening posterodorsally; concave ventrally. In dorsal view, humeri developed and distinct: evenly rounded and slightly wider than the rest of the mesosoma; mesothoracic spiracles protruding past the lateral margins of the mesosoma, visible as slight angles where the pronotum meets the mesonotum. Promesonotal suture visible as a slight disruption in the ground sculpture. Metanotal groove very faintly impressed, visible as a slight disruption in the ground sculpture. Propodeal spines broadly approximated basally and nearly parallel apically, their apices separated from each other by slightly less than their length, the negative space between them “U” shaped. Petiolar peduncle with spiracles slightly protruding past the lateral margins, but not noticeably constricted anterior to them. Petiolar node, when viewed posterodorsally, trapezoidal: much broader apically than basally; apical margin flat; node broader than the peduncle and the caudal cylinder. Postpetiole narrow (PWI 160–179) and campaniform. Anterior margin of the postpetiole convex, evenly rounding into the lateral margins, which bulge slightly anteriorly, are weakly constricted medially, then diverge slightly again to the angulate posterior corners; posterior margin flat. Metafemur moderately to strongly incrassate (FI 271–307). Sculpture: median clypeal carina present, extending posteriorly to the frontal triangle, and flanked on either side by multiple slightly weaker carinae. Lateral clypeal lobes with additional, weaker carinae; ground sculpture weakly areolate. Antennal scapes areolatecostulate. Cephalic dorsum densely rugose over areolate sculpture; fine concentric costulae surrounding the antennal insertions. Lateral surfaces of head sculptured similarly to the dorsum, but rugae forming whorls around the compound eyes. Ventral surface of head smooth and shining over the gular region, otherwise with weak costulae over weak areolate ground sculpture. Pronotal neck areolate. Lateral surfaces of the mesosoma sculptured similarly to the head, but with weak areolate sculpture between the propodeal spiracle and the base of the propodeal spine. Propodeal declivity weakly rugulose. Dorsal surface of mesosoma sculptured similarly to the cephalic dorsum and the lateral mesosoma surface. Femora shining through weak areolate sculpture. Petiole finely areolate on all surfaces but the ventral surface of the peduncle, which is smooth and shining; areolae becoming weaker on the node. Postpetiole shining through weak areolate sculpture. First gastral tergite shining but anterior quarter often weakly, indistinctly sculptured, with very weak spectral iridescence. First gastral sternite smooth and shining, without spectral iridescence. Setae: antennal scapes and funiculi with long, suberect pilosity. Dorsum of the head, pronotum, waist segments, and gaster with abundant, erect, tapering, flexuous setae, the longest of which are about one and a half times the length of the compound eye and are directed toward the midline of the body. The head bears>80, mesosoma>80, petiole ~32, postpetiole ~40, and first gastral tergite>80 setae. Pubescence present over the entire body, which is nearly as long as the setae. Color: predominantly testaceous yellow; antennae, mandibles, tibiae, and first tarsomere testaceous. Gyne measurements & indices ( n = 3): SL = 0.850 –0.923 (0.880); FRS = 0.313 –0.354 (0.328); CW = 1.034 –1.081 (1.050); CWb = 0.909 –0.963 (0.932); PoOC = 0.371 –0.408 (0.390); CL = 0.976 –1.045 (0.999); EL = 0.247 –0.274 (0.258); EW = 0.184 –0.194 (0.188); MD = 0.236 –0.249 (0.240); WL = 1.687 –1.839 (1.754); SPST = 0.456 –0.495 (0.476); MPST = 0.424 –0.509 (0.459); PEL = 0.593 –0.629 (0.608); NOL = 0.309 –0.350 (0.323); NOH = 0.174 –0.231 (0.194); PEH = 0.322 –0.410 (0.362); PPL = 0.265 –0.323 (0.294); PW = 0.899 –1.029 (0.958); SBPA = 0.444 –0.520 (0.478); SPTI = 0.407 –0.493 (0.459); PEW = 0.239 –0.271 (0.254); PNW = 0.370 –0.471 (0.409); PPW = 0.418 –0.490 (0.442); HFL = 1.004 –1.162 (1.080); HFWmax = 0.187 –0.201 (0.192); HFWmin = 0.079 –0.086 (0.083); CS = 1.397 –1.486 (1.432); ES = 0.339 –0.371 (0.353); SI = 92–96 (94); OI = 24–25 (25); CI = 92–95 (93); WLI = 183–191 (188); SBI = 48–54 (51); PSI = 25–28 (27); PWI = 166–181 (174); PLI = 195–224 (207); NI = 152–178 (168); PNWI = 154–174 (161); NLI = 51–56 (53); FI = 220–239 (232). Gyne description: In full-face view, head subquadrate, longer than broad (CI 92-95). Mandibles 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 flat medially. Antennal scapes very long: when fully retracted, surpassing the posterior margin of the head capsule by about two times the maximum width of the scape (SI 92–96). Antennae 12-segmented; antennal club composed of three segments, with the apical-most segment about 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 strongly 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 24–25), with 21 ommatidia in longest row. Mesoscutum rounded evenly anteriorly, not fully covering the dorsal surface of the pronotum, and flat dorsally. Anterior margin of mesoscutellum on the same level as the mesoscutum; dorsum flat. Posterior margin of metanotum extending past the posterior margin of the mesoscutellum. Propodeal spiracle moderately well developed, directed posterolaterally, and separated from the propodeal declivity by about five spiracle diameters. Propodeal spines stout and well developed, but short (PSI 25–28), about two thirds as long as the propodeal declivity, tapering evenly from the base, directed posterodorsally, straight, and acute. Propodeal declivity weakly concave, forming a rounded ~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 long (PLI 195–224), without tubercles anterodorsally. Subpetiolar process in the form of tiny, acute tooth, which grades evenly into the ventral margin of the petiole posteriorly. Petiolar peduncle moderately long: comprising half of the total petiole length. Petiolar node squamiform: transition between peduncle and node a rounded ~120 ° angle; anterior face rounding evenly into the posterior face, which forms a ~110 ° angle with the caudal cylinder. Postpetiole evenly rounded anterodorsally, bulging before flattening posterodorsally; concave ventrally. In dorsal view, mesoscutum not fully covering pronotum anteriorly; humeri visible laterally as rounded sclerites. Mesoscutum evenly rounded anteriorly; anterior margin rounding evenly into the lateral margins; lateral margins diverging to the wing bases, then converging to the convex posterior margin. Propodeal spines strongly diverging basally, but parallel to each other apically, their apices separated from each other by about one and a half times their length. Petiolar peduncle with spiracles weakly protruding past the lateral margins. Petiolar node, when viewed posterodorsally, roughly trapezoidal: broader apically than basally; apical margin convex; node broader than the peduncle and the caudal cylinder. Postpetiole narrow (PWI 166–181) and subquadrate. Anterior margin of postpetiole weakly convex, with corners rounding evenly into the lateral margins; lateral margins weakly converging posteriorly; posterior margin broadly concave. Metafemur weakly incrassate (FI 220–239). Sculpture: median clypeal carina present, extending from the anterior margin to frontal triangle, and flanked by multiple slightly weaker carinae. Lateral clypeal lobes with additional weaker carinae; ground sculpture weakly areolate. Antennal scapes areolatecostulate. Cephalic dorsum densely rugose over areolate ground sculpture, becoming costate between the frontal carinae; fine concentric costulae surrounding the antennal insertions. Lateral surfaces of head sculptured similarly to the dorsum. Ventral surface of head weakly costulate. Pronotal neck areolate. Lateral surfaces of the mesosoma sculptured similarly to the head. Propodeal declivity transversely rugose. Mesoscutum and mesoscutellum areolate, with fine costulate sculpture. Metanotum finely areolate. Propodeum coarsely rugose. Femora predominantly smooth and shining; basal quarter weakly areolate. Petiole finely longitudinally areolate-costulate on nearly all surfaces, but smooth and shining on the ventral surface of the petiole. Postpetiole weakly, finely areolate. First gastral tergite with fine areolate-costulate sculpture on the basal half; otherwise smooth and shining with weak spectral iridescence. First gastral sternite weakly areolate basally; otherwise smooth and shining, without spectral iridescence. Setae: antennal scapes and funiculi with long, suberect pilosity. Dorsum of the head, pronotum, waist segments, and gaster with abundant, erect, tapering, flexuous setae, the longest of which are about the width of the compound eye. Pubescence present over the entire body, which is nearly as long as the setae. Color: predominantly testaceous yellow. Antennae, masticatory margin of mandibles, tibiae, and first tarsomere dark brown. Interior of ocellar triangle, lateral margins of mesoscutum, wing bases, apex of femora, tarsi, dorsum of petiole and postpetiole, posterior margins of gastral tergites, and sting testaceous. Male measurements & indices ( n = 1): SL = 0.227; FRS = 0.086; CW = 0.686; CWb = 0.556; PoOC = 0.249; CL = 0.597; EL = 0.262; EW = 0.200; MD = 0.068; WL = 1.206; SPST = n/a; MPST = 0.312; PEL = 0.406; NOL = 0.234; NOH = 0.070; PEH = 0.183; PPL = 0.203; PW = 0.777; SBPA = n/a; SPTI = n/a; PEW = 0.176; PNW = 0.160; PPW = 0.271; HFL = 1.004; HFWmax = 0.095; HFWmin = 0.056; CS = 0.855; ES = 0.362; SI = 41; OI = 42; CI = 93; WLI = 217; SBI = n/a; PSI = n/a; PWI = 154; PLI = 200; NI = 334; PNWI = 91; NLI = 58; FI = 170. Male description: In full-face view, head subovate, slightly longer than broad (CI 93). Mandibles shining through very weak striae, and armed with five teeth: the apical-most well developed, followed by a smaller preapical tooth and three roughly equally developed smaller teeth. Anterior clypeal margin entire and weakly convex. Antennal scapes short: when fully retracted, failing to reach the posterior margin of the head capsule by about the length of the scape (SI 41). Antennae 13-segmented; antennal club composed of four segments, with the apical-most segment about 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 strongly protruding past the lateral margins of the head capsule. Lateral margin of head convex, margin between the anterior margin of the compound eye and the mandibular insertions straight. Posterior head margin evenly convex, rounding evenly into the lateral margins. In profile view, compound eyes ovular and large (OI 46), with 24 ommatidia in the longest row. Mesoscutum bulging anteriorly, fully covering the dorsal surface of the pronotum, convex dorsally. Mesoscutellum depressed slightly below the level of the mesoscutum, convex dorsally. Posterior margin of metanotum extending beyond the posterior margin of the mesoscutellum. Propodeum strongly depressed; flat dorsally and transitioning into the propodeal declivity through a broadly rounded ~95 ° angle. Propodeal spiracle moderately well developed, directed posterolaterally, and separated from the propodeal declivity by about four spiracle diameters. Propodeal spines absent. Propodeal lobes rounded and weakly developed. Metapleural gland bulla small, extending a sixth of the way between the insertion of the metacoxa and the propodeal spiracle. Petiole moderately long (PLI 200), without tubercles anterodorsally. Subpetiolar process a minute, acute tooth; ventral margin of petiole bulging slightly posterior to it. Petiolar peduncle moderately long: comprising about half of the total petiole length. Petiolar node low and truncated dorsally. Postpetiole evenly rounded anterodorsally, bulging slightly before flattening dorsally, and concave ventrally. In dorsal view, mesoscutum fully covering pronotum anteriorly; humeri not visible laterally. Petiolar peduncle with spiracles strongly protruding past the lateral margins. Petiolar node narrower than the peduncle where the spiracles arise, but broader than the caudal cylinder; trapezoidal when view at a posterodorsal aspect, the apex flat and narrower than the base. Postpetiole narrow (PWI 154) and campaniform. Anterior margin of postpetiole weakly convex, with the anterior corners evenly rounding into the lateral margins, which evenly diverge to the angulate posterior corners; posterior margin of postpetiole flat. Metafemur not incrassate (FI 170). Sculpture: median clypeal carina present, extending from the anterior margin of the clypeus to the frontal triangle, flanked on either side by one weaker carina. Antennal scapes shining. Dorsum of head areolate, with weak rugae between the compound eye and antennal insertion. Lateral surface of head areolate, with weak rugae between the compound eye and mandibular insertion. Ventral surface of head shining, with weak areolae. Pronotal neck weakly areolate. Anterior face of pronotum shining through weak areolate sculpture. Lateral surface of pronotum predominantly weakly areolate. Katepisternum weakly areolate, with sculpture becoming weaker on the posterior two thirds. Anepisternum predominantly smooth and shining, with weak areolate sculpture around the margins. Metapleuron predominantly smooth and shining, with a small patch of weak areolate sculpture over the metapleural gland bulla. Lateral face of the propodeum areolate. Propodeal declivity smooth and shining. Dorsally, mesoscutum areolatecostulate, with a smooth and shining strip anteromedially. Mesoscutellum predominantly areolate-costulate, but sculpture weaker medially. Femora smooth and shining. Petiole predominantly smooth and shining, but base of node weakly, indistinctly sculptured; dorsum of peduncle weakly rugulose. Dorsal surface of postpetiole shining, with traces of weak areolate sculpture laterally and on the posterior quarter. First gastral tergite and sternite smooth and shining, without spectral iridescence. Setae: antennal scapes and funiculi with long, suberect pilosity. Dorsum of the head, pronotum, waist segments, and gaster with abundant, erect, tapering, flexuous setae, the longest of which are about one and a half times the width of the compound eye. Pubescence present over the entire body, which is nearly as long as the setae. Color: predominantly dark brown, with light yellow, nearly white antennae, mouthparts, legs, and genitalia. Etymology: Morphological, from ‘aztecus’ + Latin ‘-oides’ (= resembling), in reference to the superficial similarity between this species and Temnothorax aztecus . Comments: Temnothorax aztecoides sp. nov. is known from several collections made from mid elevation wet forests in Veracruz and Oaxaca States, Mexico . This species apparently nests primarily in hollow twigs and vines suspended from live trees, and forages arboreally like many of its close relatives in the salvini species group. Temnothorax aztecoides sp. nov. is not particularly closely related to T. aztecus (having shared a common ancestor approximately 10 Ma ( Prebus, 2021 )), but the two species are very similar in appearance and have overlapping geographical ranges, especially in the Los Tuxtlas mountain complex (and probably the southern Sierra Madre) in Mexico ( Figs. 153A & 153B ). Temnothorax aztecoides sp. nov. appears to inhabit higher elevations (> 1,000 m ), while T. aztecus inhabits lower elevations (< 1,200 m ) ( Figs. 153A & 153B ).