Temnothorax altinodus

Known only from the holotype.

Identification
Prebus (2021) – The lone member of the altinodus group of the Temnothorax salvini clade. Temnothorax altinodus 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 83); mesosoma relatively elongate (WLI 148); dorsum of propodeum without erect setae; propodeal spines directed dorsally; hind femora strongly incrassate (FI 327); petiole with a weak transverse carina anterodorsally; petiolar node compact (NI 143); in dorsal view, apex of petiolar node narrower than caudal cylinder; petiolar node dorsally rounded; postpetiole moderately broad (PWI 202); integument predominantly black; setae on head, mesosoma, waist segments and gaster erect, moderately long, sparse and blunt (never long and tapering).

Similar species: Temnothorax achii, Temnothorax acuminatus, Temnothorax acutispinosus, Temnothorax ixili, Temnothorax subditivus, Temnothorax tuxtlanus, Temnothorax xincai, members of the augusti and pulchellus groups, and species of the sallei clade. Temnothorax altinodus can be distinguished from similar appearing members of the sallei clade, e.g. Temnothorax manni, Temnothorax mexicanus, Temnothorax punctithorax by the sculpture of the head: in similar looking sallei cladespecies, the head is mostly smooth and shining, with concentric costulae surrounding the antennal insertions; additionally, the medial lobe of the clypeus is typically smooth, with three distinct carinae, whereas it is densely costulate-rugulose in T. altinodus In contrast to all of the remaining species above, the petiole of T. altinodus has a weak transverse carina anterodorsally, a feature not found in other members of the salvini clade, except for T. acuminatus, T. tuxtlanus, Temnothorax rugosus, and members of the annexus group. Temnothorax altinodus is easily separated from T. acutispinosus, T. acuminatus and T. tuxtlanus by the hind femora, which are incrassate in T. altinodus; it may be distinguished from T. rugosus and the members of the annexus group by the anterior margin of the clypeus, which entire in T. altinodus, as opposed to medially emarginate.

Distribution based on Regional Taxon Lists
Neotropical Region: Honduras.

Biology
Prebus (2021) - Temnothorax altinodus is known only from the holotype worker, collected via beating vegetation in a mid-elevation mesophyll forest in northwestern Honduras. This species is most closely related to the exclusively arboreally nesting fuscatus species group, which ranges from Central Mexico to Costa Rica, and the pergandei group, ground nesting species ranging from the northern United States to Nicaragua (Prebus, in prep.).

Nomenclature

 * . Temnothorax altinodus Prebus, 2021: 89, fig. 94 (w.) HONDURAS.

Worker
(n = 1): SL = 0.607; FRS = 0.223; CW = 0.773; CWb = 0.727; PoOC = 0.343; CL = 0.823; EL = 0.188; EW = 0.131; MD = 0.164; WL = 1.079; SPST = 0.252; MPST = 0.353; PEL = 0.38; NOL = 0.22; NOH = 0.154; PEH = 0.272; PPL = 0.190; PPH = 0.276; PW = 0.499; SBPA = 0.197; SPTI = 0.266; PEW = 0.157; PNW = 0.146; PPW = 0.317; HFL = 0.715; HFWmax = 0.209; HFWmin = 0.064; CS = 1.1385; ES = 0.254; SI = 83; OI = 22; CI = 88; WLI = 148; SBI = 27; PSI = 23; PWI = 202; PLI = 200; NI = 143; PNWI = 93; NLI = 58; FI = 327.

In full-face view, head subquadrate, longer than broad (CI 88). 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 flat medially. 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 83). Antennae 12-segmented; antennal club of composed of three segments, with the apical-most segment about one and a half times as long as 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 weakly 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 small (OI 22), with 11 ommatidia in longest row. Pronotal declivity indistinct, neck and anterior face of pronotum forming a ~120° angle. Mesosoma evenly rounded anteriorly and flat dorsally to the bases of the propodeal spines. Promesonotal suture extending from the posterior margin of the procoxal insertion 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 well developed, directed posterolaterally, and separated from the propodeal declivity by about three spiracle diameters. Propodeal spines moderately well developed (PSI 23), about as long as the propodeal declivity, tapering evenly from the base, straight, and acute. 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 moderately long (PLI 200), with moderately well-developed tubercles anterodorsally. Subpetiolar process in the form of a small, posteriorly directed, blunt tooth; ventral margin of petiole flat concave posterior to it. Petiolar peduncle short: comprising about a third of the total length of the petiole. Petiolar node erect: transition between peduncle and node marked by a rounded angle of ~140°, resulting in a weakly concave anterior node face; anterior face forming a ~90° angle with the dorsal face, which is weakly convex; dorsal face meeting the posterior face at a ~100° angle; posterior face forming a ~90° angle with the caudal cylinder. Postpetiole evenly rounded anterodorsally, bulging before flattening posterodorsally; lobed ventrally.

In dorsal view, humeri developed and distinct: evenly rounded and 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. Promesonotal suture visible as a slight disruption in the ground 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 and diverging apically, their apices separated from each other by about their length, the negative space between them "U" shaped. Petiolar peduncle with spiracles protruding past the lateral margins; peduncle broadened where they arise. Petiolar node subquadrate; node slightly broader than the peduncle, and evenly grading into the caudal cylinder, which is slightly wider than the node. Postpetiole moderately broad (PWI 202) and campaniform, articulating with the nearly the entire anterior margin of the gaster but leaving small angulate corners exposed. Anterior margin of the postpetiole weakly convex and evenly rounds into the lateral margins, which diverge slightly to the angulate posterior corners; posterior margin flat. Metafemur incrassate (FI 327).

Sculpture: median clypeal carina present, extending posteriorly 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 areolatecostulate. Cephalic dorsum densely areolate-rugulose, with fine rugose sculpture overlying it. Lateral surfaces of sculptured similarly to the dorsum, but with areolate-rugulose sculpture becoming stronger between compound eye and mandibular insertion. Ventral surface of head longitudinally areolate-costulate. Pronotal neck weakly areolate. Lateral surfaces of mesosoma densely areolate, with fine rugose-costulate sculpture overlying it. Propodeal declivity weakly areolate. Dorsal surface of mesosoma densely areolate, with fine rugose overlying it. Femora shining through weak areolate sculpture. Petiole uniformly areolate; a weak carina present laterally, extending longitudinally from the anterodorsal flange to the caudal cylinder, passing through the petiolar spiracle. Postpetiole uniformly areolate. First gastral tergite weakly areolate on the basal quarter, otherwise smooth and shining, with weak spectral iridescence. First gastral sternite smooth and shining.

Setae: antennal scapes and funiculi with short, adpressed pilosity. Dorsum of the head, pronotum, waist segments, and gaster with sparse, short, erect, blunt-tipped setae, the longest of which are slightly less than the width of the compound eye. The head bears ~16, mesosoma ~8 restricted to the promesonotum, petiole 2, postpetiole ~4, and first gastral tergite ~20 setae. Short, sparse pubescence present over the entire body, but difficult to detect against the densely sculptured integument.

Color: predominantly black, with dark brown antennae, mandibles, and legs (excluding tarsi). Tarsi and sting testaceous yellow.

Type Material
Holotype worker: HONDURAS: Cortés: Parque Nacional Cusuco, ± 70 m, 1,290 m, 1 June 2010, LLAMA#Go-C-06-4-03, mesophyll forest, beating vegetation (CASENT0617708).

Etymology
Morphological, from the Latin ʻaltus' (= high, tall) + ʻnodus' (= node), a reference to the very tall petiolar node.