Temnothorax xincai

Temnothorax xincai is known only from a couple of Winkler leaf litter extractions made in high elevation pine forests in southern Guatemala. This species is closely related to Temnothorax ixili and Temnothorax achii, which are also known from low to high elevation leaf litter extractions and nests in Oncidium orchids. (Prebus 2021)

Identification
Prebus (2021) – A member of the goniops group of the Temnothorax salvini clade. Temnothorax xincai can be separated from all other species in the salvini clade by the following character combination: antennal scapes short, failing to reach the posterior margin of the head capsule by about the maximum width of the scape (SI 89); compound eyes small (OI 24); head sculpture mostly smooth and shining; body moderately compact (WLI 141); metanotal groove absent; propodeum moderately depressed; propodeal spines about as long as the propodeal declivity (PSI 21); propodeal spines broadly approximated in dorsal view (SBI ~ 29); hind femora moderately incrassate (FI 293); petiolar node erect and dorsally rounded, not overhanging the caudal cylinder in profile view; petiolar node compact, not elongate (NI 155); petiolar node slightly broader than caudal cylinder in dorsal view (PNWI < 122); dorsum of postpetiole smooth and shining; antennal scapes with short, decumbent pilosity; setae on head, mesosoma, waist segments and gaster erect, short, sparse and blunt (never long and tapering); integument predominantly dark brown, with trochanters, meso- and metacoxae, tibiae, tarsi, and sting very light yellow.

Similar species: Temnothorax subditivus, Temnothorax tenuisculptus, species of the augusti, goniops, and pulchellus groups, species of the sallei clade. Temnothorax xincai can be distinguished from similar appearing members of the sallei clade(e.g., Temnothorax manni, Temnothorax mexicanus, Temnothorax punctithorax) by the petiole, which lacks a transverse carina anterodorsally. Temnothorax xincai can be separated from T. subditivus and the augusti group by the structure of the petiolar node, which is erect, dorsally rounded, and only slightly broader than the caudal cylinder in dorsal view, as opposed to squamiform in T. subditivus, or leaning posteriorly over the caudal cylinder in the augusti group. In contrast to T. tenuisculptus, T. xincai has moderately incrassate hind femora (FI < 300). Temnothorax xincai can be distinguished from the pulchellus group by the combination of a relatively longer mesosoma (WLI >135 vs. < 135 in most pulchellus group members). Some members of the pulchellus group may approach these dimensions (e.g., Temnothorax agavicola, Temnothorax albispinus, Temnothorax flavidulus, Temnothorax hippolyta, Temnothorax laticrus, Temnothorax terricola, Temnothorax torrei, and Temnothorax wilsoni), but they can be separated from T. xincai by their very broad postpetioles (PWI >220). Temnothorax xincai can be distinguished from other goniops group members by the relatively short, basally flared propodeal spines (PSI 21; longer than the propodeal declivity and spiniform in Temnothorax goniops and Temnothorax huehuetenangoi), the smooth and shining head and postpetiole (sculptured in Temnothorax ixili and Temnothorax achii).

Distribution
Known from high elevation sites in Santa Rosa (southern), Guatemala.

Distribution based on Regional Taxon Lists
Neotropical Region: Guatemala.

Nomenclature

 * . Temnothorax xincai Prebus, 2021: 194, figs. 114D, 119 (w.q.) GUATEMALA.

Worker
(n = 1): SL = 0.458; FRS = 0.188; CW = 0.560; CWb = 0.515; PoOC = 0.232; CL = 0.617; EL = 0.143; EW = 0.112; MD = 0.129; WL = 0.725; SPST = 0.153; MPST = 0.241; PEL = 0.298; NOL = 0.181; NOH = 0.117; PEH = 0.197; PPL = 0.170; PPH = 0.197; PW = 0.367; SBPA = 0.150; SPTI = 0.207; PEW = 0.139; PNW = 0.170; PPW = 0.295; HFL = 0.508; HFWmax = 0.117; HFWmin = 0.040; CS = 0.824; ES = 0.199; SI = 89; OI = 24; CI = 83; WLI = 141; SBI = 29; PSI = 21; PWI = 212; PLI = 175; NI = 155; PNWI = 122; NLI = 61; FI = 293.

In full-face view, head subquadrate, longer than broad (CI 83). Antennal scapes short: when fully retracted, failing to reach the posterior margin of the head capsule by about the maximum width of the scape (SI 89). Mandibles densely, finely striate but weakly 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 evenly convex medially. Antennae 12-segmented; antennal club of composed of three segments, with the apical-most segment longer than 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 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 24), with 10 ommatidia in longest row. Pronotal declivity indistinct, neck and anterior face of pronotum forming a ~120° angle. Mesosoma sinuate: very strongly convex from where it joins the pronotal neck to the propodeum, which is flat and rounds evenly into the base of the propodeal spines. Promesonotal suture extending from the posterior margin of the procoxal insertion to the mesothoracic spiracle, which is moderately well developed; suture continues dorsally as a weak sulcus. 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 moderately well developed, directed laterally, and separated from the propodeal declivity by about four spiracle diameters. Propodeal spines moderately well developed, but short (PSI 21), slightly shorter than the propodeal declivity, tapering evenly from the base, weakly downcurved near the apices, 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 small, extending from the metacoxal insertion halfway to the propodeal spiracle. Petiole moderately long (PLI 175), without tubercles anterodorsally. Subpetiolar process in the form of an acute, triangular tooth; ventral margin of petiole flat posterior to it. Petiolar peduncle short: comprising about a third of the length of the petiole. Petiolar node robust and erect, subquadrate: transition between peduncle and node marked by a rounded angle of ~120°, resulting in a concave anterior node face; anterior face meeting the dorsal face at a rounded angle of ~110°; dorsal face weakly convex, meeting the posterior face at a rounded ~90° angle; posterior face forms a ~90° angle with the caudal cylinder. Postpetiolar dorsum evenly rounded; weakly lobed ventrally.

In dorsal view, humeri developed: evenly rounded and 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 indicated by a band of denser sculpture. 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, bases joined by a rounded transverse welt, and diverging apically, their apices separated from each other by slightly less than their length, the negative space between them "U" shaped. Petiolar peduncle with spiracles not protruding past the lateral margins; peduncle not noticeably constricted anterior to them. Petiolar node ovular and longitudinally elongate, the anterior of the node narrower than the posterior margin; node tapering, so that the apex is narrower than the base. Base of node wider than the peduncle, and about one and quarter times as wide as the caudal cylinder. Postpetiole moderately broad (PWI 212) and campaniform, articulating with most of the anterior margin of the gaster, leaving small, angulate margins on each side exposed. Anterior margin of the postpetiole flat and evenly rounds into the lateral margins, which diverge slightly to the angulate posterior corners; posterior margin flat. Metafemur moderately incrassate (FI 293).

Sculpture: median clypeal carina present, extending from the anterior margin of the clypeus to the level of the antennal insertions, and flanked by two slightly weaker carinae. Lateral clypeal lobes with additional, weaker carinae; ground sculpture shining through weak areolate sculpture. Antennal scapes weakly areolate-costulate. Cephalic dorsum smooth and shining, with costulae flanking the frontal carinae medially, extending just beyond the level of the posterior margins of the compound eyes. Lateral surfaces of head predominantly smooth and shining, but with areolate sculpture on the ventral margin behind the compound eye and strongly rugose sculpture between the compound eye and mandibular insertion. Ventral surface of head weakly, finely areolate-costulate posteromedially, otherwise smooth and shining. Pronotal neck weakly areolate. Lateral surface of the pronotum rugulose anteriorly, and smooth and shining on the posterior half. Lateral surface of the rest of the mesosoma areolate, but with smooth and shining patches anterior and posterior to the propodeal spiracles. Propodeal declivity smooth and shining. Dorsal surface of pronotum finely costulate, but smooth and shining medially. Pronotum delineated from the mesonotum by a transverse strip of dense, rugulose sculpture. Mesonotum and propodeum weakly longitudinally areolate-costulate, but smooth and shining medially. Mesonotum delineated from the propodeum by an indistinct transverse sulcus. Femora shining, with weak areolate sculpture on the distal third. Petiole weakly areolate laterally, but smooth and shining anteriorly, and weakly areolate-costulate dorsally. Postpetiole predominantly smooth and shining, but with weakly areolate-strigulate on the posterodorsal half. First gastral tergite smooth and shining, with weak spectral iridescence. First gastral sternite smooth and shining.

Setae: antennal scapes and funiculi with short, decumbent pilosity. Dorsum of the head, pronotum, waist segments, and gaster with moderately abundant, erect, blunt-tipped setae, the longest of which are about the width of the compound eye. The head bears ~30, mesosoma ~20, petiole 6, postpetiole ~8, and first gastral tergite ~26 setae. Short, sparse pubescence present over the entire body, but difficult to detect against the areolate sculpture.

Color: predominantly dark brown, with mandibles and antennae testaceous yellow. Procoxae, sting, and femora testaceous. Trochanters, meso- and metacoxae, tibiae, and tarsi very pale yellow, nearly white.

Queen
(n = 1): SL = 0.483; FRS = 0.206; CW = 0.661; CWb = 0.620; PoOC = 0.231; CL = 0.636; EL = 0.210; EW = 0.160; MD = 0.115; WL = 1.083; SPST = 0.205; MPST = 0.290; PEL = 0.388; NOL = 0.168; NOH = 0.133; PEH = 0.240; PPL = 0.204; PPH = 0.290; PW = 0.633; SBPA = 0.296; SPTI = 0.275; PEW = 0.188; PNW = 0.221; PPW = 0.370; HFL = 0.584; HFWmax = 0.129; HFWmin = 0.050; CS = 0.938; ES = 0.290; SI = 78; OI = 31; CI = 97; WLI = 175; SBI = 48; PSI = 19; PWI = 197; PLI = 190; NI = 126; PNWI = 118; NLI = 43; FI = 258.

In full-face view, head subquadrate, about as long as broad (CI 97). 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 evenly convex medially. Antennal scapes short: when fully retracted, failing to reach the posterior margin of the head capsule by about half the maximum width of the scape (SI 78). Antennae 12-segmented; antennal club composed of three segments, with the apical-most segment 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 moderately protruding past the lateral margins of the head capsule. Lateral margin of head behind the compound eyes weakly convex; below the compound eyes, lateral margins converging to the mandibular insertions. Posterior head margin flat, rounding evenly into the lateral margins.

In profile view, compound eyes ovular and large (OI 31), with 16 ommatidia in longest row. Mesoscutum rounded evenly anteriorly, covering the dorsal surface of the pronotum, and flat dorsally. Mesoscutellum on the same level as the mesoscutum. Posterior margin of metanotum extending slightly 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 moderately well developed (PSI 19), about half as long as the propodeal declivity, triangular, directed posteriorly, straight, and acute. Propodeal declivity weakly concave, forming a rounded ~110° angle with the base of the propodeal spines. Propodeal lobes rounded and very weakly developed. Metapleural gland bulla moderately large, extending from the metacoxal insertion two thirds of the way to the propodeal spiracle. Petiole moderately long (PLI 190), without tubercles anterodorsally. Subpetiolar process in the form of a very small, triangular, very acute tooth, which grades evenly into the ventral margin of the petiole posteriorly; ventral margin of petiole very weakly bulging. Petiolar peduncle short: comprising about a third of the length of the petiole. Petiolar node robust and erect, evenly rounded: transition between peduncle and node indistinct, marked by a rounded angle of ~140°, resulting in a concave anterior node face; anterior face rounding evenly into the dorsal face, which is evenly convex; dorsal face rounding evenly into the posterior face, which forms a ~100° angle with the caudal cylinder. Postpetiole flat anteriorly, bulging slightly anterodorsally before flattening posterodorsally; ventral surface lobed.

In dorsal view, mesoscutum covering pronotum anteriorly, but humeri visible laterally as rounded sclerites. Propodeal spines weakly diverging apically, their apices separated from each other by about three times their length. Petiolar peduncle with spiracles not protruding past the lateral margins. Petiolar node campaniform: evenly convex anteriorly, and flat posteriorly; node tapering, so that the apex is narrower than the base. Base of node wider than the peduncle, and about one and quarter times as wide as the caudal cylinder. Postpetiole subquadrate, narrow (PWI 197), and articulating with most of the anterior margin of the gaster, leaving small, angulate margins on each side exposed. Anterior margin of postpetiole weakly 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 258).

Sculpture: median clypeal carina present, extending from the anterior margin of the clypeus to the level of the antennal insertions, and flanked by two slightly weaker carinae. Lateral clypeal lobes with additional weaker carinae; ground sculpture weakly areolate. Antennal scapes very weakly areolate-costulate. Cephalic dorsum costate with weaker cross reticulations; very fine concentric costulae surrounding the antennal insertions; strip of smooth and shining sculpture extending from the frontal triangle to the median ocellus; posterior to the median ocellus, the strip of smooth and shining sculpture broadening to the width separating the lateral ocelli. Lateral surfaces of head costate, with rugose sculpture surrounding the compound eye, and between the compound eye and the mandibular insertion. Ventral surface of head shining through weak areolate-costulate sculpture. Pronotal neck shining through weak areolate sculpture. Lateral surfaces of the mesosoma areolate-costulate, becoming weaker on the posteromedial part of the lateral face of the pronotum, anterior third of the mesopleurae, and in small patches anterior and posterior to the propodeal spiracle. Propodeal declivity weakly strigulate. Mesoscutum costulate, with smooth and shining sculpture in a small patch anteromedially, and in two patches near the wing bases. Mesoscutellum predominantly smooth and shining, with indications of weak costulae. Femora shining through traces of weak areolate sculpture. Petiole and postpetiole weakly longitudinally areolate-costulate laterally. Dorsal face of the peduncle weakly, finely areolate. Anterior face of the petiolar node smooth and shining; dorsal face of the node with fine concentric costulae. Postpetiole smooth and shining anteriorly; dorsal surface with fine concentric areolate-costulate sculpture. First gastral tergite smooth and shining, without spectral iridescence. First gastral sternite smooth and shining.

Setae: antennal scapes and funiculi with short, decumbent pilosity. Dorsum of the head, pronotum, waist segments, and gaster with moderately abundant, erect, blunt-tipped setae, the longest of which are about half the width of the compound eye. Short, sparse pubescence present over the entire body, but difficult to detect against the areolate sculpture.

Color: predominantly dark brown, with mandibles and antennae testaceous yellow. Procoxae, sting, and femora testaceous. Trochanters, meso- and metacoxae, tibiae, and tarsi very pale yellow, nearly white.

Type Material
Holotype worker: GUATEMALA: Santa Rosa: Volcán Tecuamburro, ± 20 m, 1,469 m, 19 April 2014, Barrios & Bustamonte #302, pine forest, ex sifted leaf litter (CASENT0632983).

Paratype workers: same data as holotype, 1 worker (CASENT0869157) 1 worker (CASENT0869158).

Etymology
Geographical, from ʻxincaâʼ, one of the many Mayan dialects spoken by the indigenous people of Guatemala.