Temnothorax aureus

Identification
Prebus (2021) - The following character combination separates Temnothorax aureus from all other species in the salvini clade: head relatively narrow (CI 77-81); antennal scapes moderately long, surpassing the posterior margin of the head by the maximum width of the scape (SI 106-108); mesosoma about one and a half times as long as the width of the head (WLI 147-152); propodeal spines about as long as the length of the propodeal declivity (PSI 36-40); petiolar node subquadrate, overhanging the caudal cylinder of the petiole; postpetiole moderately broad, more than two times the width of the petiole in dorsal view (PWI 205-218); erect setae on the dorsal surface of the head; integument testaceous yellow.

Similar species: Temnothorax acutispinosus, Temnothorax subditivus, Temnothorax tenuisculptus, Temnothorax tuxtlanus, species of the annexus, augusti, fuscatus, and salvini groups. Temnothorax aureus can be distinguished from the first three species by the shape of the dorsal margin of the mesosoma in profile, which is weakly, evenly convex: in T. subditivus, the mesosoma is strongly arched, while sinuate in T. tenuisculptus and T. tuxtlanus Petiolar node shape is also a useful character for separating T. aureus from the above taxa: T. subditivus and the potentially co-occurring members of the salvini group have a squamiform petiolar node, which is much broader than the peduncle in dorsal view (only slightly wider in T. aureus), and the nodes of the annexus group and T. tenuisculptus are erect and subquadrate, as opposed to leaning posteriorly in T. aureus; T. tuxtlanus and T. acutispinosus have rounded petiolar nodes in profile view. Temnothorax aureus can also be distinguished from T. tuxtlanus and T. acutispinosus by the presence of erect setae on the dorsum of the propodeum. The potentially co-occurring members of the fuscatus group have a low, elongate petiolar node in profile view. Finally, T. aureus can be separated from fellow members of the augusti group by the combination of long propodeal spines, which are about as long as the length of the propodeal declivity (shorter than the declivity in Temnothorax augusti and Temnothorax casanovai), the relatively narrow head (broader in Temnothorax leucacanthoides: CI 77-81 vs. >84); relatively long antennal scapes (SI 106-108 vs. < 105 in Temnothorax leucacanthus and T. leucacanthoides).

This species closely resembles a lightly colored form T. leucacanthus and T. leucacanthoides from Southern Mexico; the latter species was found nesting in dead vegetation in littoral habitat.

Distribution
Low elevation Pacific slope of Southern El Salvador to Northwest Nicaragua.

Distribution based on Regional Taxon Lists
Neotropical Region: El Salvador, Honduras, Nicaragua.

Biology
Prebus (2021) - Temnothorax aureus is apparently broadly distributed on the Pacific Slope of Central America but known only from collections of stray workers made at low elevations. This species closely resembles a lightly colored form T. leucacanthus and T. leucacanthoides from Southern Mexico; the latter species was found nesting in dead vegetation in littoral habitat.

Nomenclature

 * . Temnothorax aureus Prebus, 2021: 128, figs. 101B, 103 (w.) NICARAGUA.

Worker
(n = 4): SL = 0.588-0.639 (0.621); FRS = 0.201-0.227 (0.216); CW = 0.606-0.649 (0.635); CWb = 0.546-0.601 (0.579); PoOC = 0.251-0.287 (0.278); CL = 0.676-0.752 (0.729); EL = 0.155-0.174 (0.165); EW = 0.112-0.123 (0.120); MD = 0.157-0.191 (0.179); WL = 0.802-0.909 (0.865); SPST = 0.310-0.337 (0.326); MPST = 0.260-0.271 (0.266); PEL = 0.324-0.380 (0.360); NOL = 0.144-0.215 (0.182); NOH = 0.131-0.145 (0.140); PEH = 0.245-0.255 (0.248); PPL = 0.162-0.196 (0.178); PPH = 0.202-0.221 (0.211); PW = 0.409-0.452 (0.433); SBPA = 0.174-0.195 (0.186); SPTI = 0.239-0.292 (0.270); PEW = 0.145-0.154 (0.150); PNW = 0.166-0.189 (0.180); PPW = 0.314-0.330 (0.320); HFL = 0.607-0.690 (0.665); HFWmax = 0.165-0.191 (0.176); HFWmin = 0.046-0.060 (0.055); CS = 0.884-0.977 (0.943); ES = 0.211-0.236 (0.225); SI = 106-108 (107); OI = 23-25 (24); CI = 77-81 (79); WLI = 147-152 (149); SBI = 30-35 (32); PSI = 36-40 (38); PWI = 205-218 (213); PLI = 194-213 (202); NI = 110-148 (129); PNWI = 114-123 (120); NLI = 44-58 (50); FI = 284-385 (326).

In full-face view, head subquadrate, elongate (CI 77-81). 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 evenly rounded medially. Antennal scapes moderately long: when fully retracted, surpassing the posterior margin of the head capsule by about the maximum width of the scape (SI 106-108). 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 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 medially weakly emarginate, but predominantly flat, rounding evenly into the lateral margins.

In profile view, compound eyes ovular and moderately large (OI 23-25), with 12 ommatidia in longest row. Pronotal declivity indistinct, but neck and anterior face of pronotum forming a ~120° angle; anterior face evenly rounding into the dorsal face. Mesosoma evenly, but 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 moderately well developed, directed posterolaterally, and separated from the propodeal declivity by about four spiracle diameters. Propodeal spines well developed and very long (PSI 36-40), slightly longer than the propodeal declivity, tapering evenly from the base, upturned at the tips, and acute. Propodeal declivity flat, forming a rounded ~110° 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 194-213), without tubercles anterodorsally. Subpetiolar process in the form of an acute tooth, ventral margin of petiole very weakly bulging medially. Petiolar peduncle long: comprising two thirds the length of the petiole. Petiolar node robust and erect, nearly squamiform: transition between peduncle and node marked by a rounded angle of ~120°, resulting in a concave anterior node face; anterior face rounding evenly into the dorsal face, which is evenly convex and slightly bulging; dorsal face rounding evenly into the short posterior face, which forms a ~85° angle with the caudal cylinder, overhanging it. Postpetiole evenly rounded anterodorsally, rounding evenly into the flattened dorsal face; weakly lobed ventrally.

In dorsal view, dorsal margin of pronotum delimited from the pronotal declivity by a weak carina. Humeri developed: evenly rounded and wider than the rest of the mesosoma; mesothoracic spiracles very weakly protruding past the lateral margins of the mesosoma, visible as slight angles where the pronotum meets the mesonotum. Promesonotal suture visible as a disruption in the 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, diverging weakly 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; peduncle weakly constricted anterior to them. Petiolar node campaniform: very weakly convex posteriorly, nearly flat; node broader than the peduncle, and slightly wider than the caudal cylinder. Postpetiole subquadrate and moderately broad (PWI 205-218), articulating with most of the anterior margin of the gaster, leaving small, angulate margins on each side exposed. Anterior margin of the postpetiole flat, evenly rounding into the lateral margins, which are parallel to the angulate posterior corners; posterior margin broadly concave. Metafemur moderately to strongly incrassate (FI 284-385).

Sculpture: median clypeal carina present, extending posteriorly nearly to the frontal triangle, and slightly stronger than the numerous carinae that flank it. Lateral clypeal lobes with additional, weaker carinae; ground sculpture areolate. Antennal scapes areolate. Cephalic dorsum areolate, but with fine rugae overlying the ground sculpture, becoming costate between the frontal carinae; fine concentric costulae surrounding the antennal insertions. Lateral surfaces of head sculptured similarly to the dorsum of the head, but with rugae becoming costate posterior to the compound eye. Ventral surface of head shining through weak areolate-costulate sculpture. Mesosoma with areolate sculpture on the pronotal neck. Lateral surface of the mesosoma strongly areolate, with fine rugose-costate sculpture on the pronotum, on the border of the meso- and metapleurae, and on the propodeal declivity. Dorsal surface of mesosoma areolate, with rugose-costate sculpture overlying the ground sculpture. Femora areolate. Petiole and postpetiole predominantly areolate, but sculpture is weaker on the ventral surface of the petiolar peduncle. Basal half of first gastral tergite weakly, finely areolate-rugulose, with spectral iridescence, otherwise smooth and shining. First gastral sternite with spectral iridescence.

Setae: antennal scapes and funiculi with short, decumbent pilosity. Dorsum of the head, pronotum, waist segments, and gaster with moderately abundant, erect, blunt-tipped, nearly clavate setae, the longest of which are slightly shorter than the width of the compound eye. The head bears ~28, mesosoma ~24, petiole 4, postpetiole ~14, and first gastral tergite ~58 setae. Short, sparse pubescence present over the entire body, but difficult to detect against the ground sculpture and light integument.

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

Type Material
Holotype worker: NICARAGUA: Estelí: 16 km N Estelí, ± 100 m, 870 m, 25 April 2011, J. Longino # JTL7420-s, tropical dry scrub, strays (CASENT0619363).

Paratype worker: NICARAGUA: Estelí: same data as holotype, 1 worker (CASENT0619364).

Etymology
Morphological, from the Latin ʻaureus' (= golden).