Temnothorax longicaulis

An arboreally nesting and foraging species.

Identification
Prebus (2021) – A member of the salvini group of the Temnothorax salvini clade. Temnothorax longicaulis can be separated from all other species in the salvini clade by the following character combination: dorsum of mesosoma very 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 minute and triangular; petiolar node strongly squamiform: in dorsal view, petiolar node greater than or equal to 1.6 times as broad as caudal cylinder; setae on head, mesosoma, legs, waist segments and gaster erect to suberect, long, abundant and tapering; integument predominantly dark brown.

Similar species: Fellow members of the salvini group. Temnothorax longicaulis 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 Temnothorax longinoi, Temnothorax quetzal, Temnothorax fortispinosus, Temnothorax parvidentatus, and Temnothorax salvini), dark brown integument (Temnothorax aztecus, Temnothorax aztecoides, Temnothorax paraztecus, T. parvidentatus, and T. quetzal are variously colored, but never uniformly dark brown), relatively small subpetiolar tooth (longer than the setae that arises directly above it in T. aztecus, T. longinoi, and T. paraztecus), and long propodeal spines (shorter than the propodeal declivity in T. salvini).

Distribution
Low-to-mid elevations along the Pacific slope of the southern Central American cordilleras of Costa Rica.

Distribution based on Regional Taxon Lists
Neotropical Region: Costa Rica.

Biology
Prebus (2021) - Temnothorax longicaulis is known from several collections from low-to-mid elevation wet forests in southern Mesoamerica. Workers have been found several times foraging on low vegetation. Temnothorax longicaulis is apparently restricted to the Pacific slope of the southern Central American cordilleras, where it may be found sympatrically with T. salvini. This latter species is also restricted to southern Central America, but its range also includes the Caribbean slope, and has a generally higher elevational range ( >1,500 m vs. < 1,300 m). Temnothorax longicaulis and T. salvini are sister species, having shared a common ancestor around 5 Ma which had dispersed to the southern Central American cordilleras from the Central American Nucleus during a mountain building phase in southern Central America during the Miocene-Pliocene transition (Prebus, 2020). These two species together are closely related to the morphologically similar T. longinoi, which is restricted to the Central American Nucleus. Temnothorax longicaulis, like its close relatives in the salvini species group, is arboreally nesting and foraging.

Nomenclature

 * obscurior. Macromischa salvini var. obscurior Forel, 1899c: 57 (w.) PANAMA.
 * [Unresolved junior secondary homonym of obscurior Dalla Torre, above (Bolton, 1995b: 242).]
 * Combination in Leptothorax: Baroni Urbani, 1978b: 495.
 * Combination in Temnothorax: Bolton, 2003.
 * Replacement name: Temnothorax longicaulis Prebus, 2021: 383.
 * . Temnothorax longicaulis Prebus, 2021: 383, figs. 153D, 157 (w.) COSTA RICA.
 * Replacement name for Macromischa salvini obscurior Forel, 1899. [Junior secondary homonym of Temnothorax obscurior (Dalla Torre, 1893).]

Worker
Prebus (2021) - (n = 6): SL = 0.737-0.845 (0.797); FRS = 0.257-0.308 (0.286); CW = 0.805-0.903 (0.875); CWb = 0.714-0.785 (0.768); PoOC = 0.316-0.340 (0.325); CL = 0.824-0.897 (0.875); EL = 0.210-0.233 (0.226); EW = 0.136-0.163 (0.153); MD = 0.198-0.235 (0.211); WL = 1.081-1.231 (1.189); SPST = 0.340-0.433 (0.390); MPST = 0.332-0.376 (0.355); PEL = 0.391-0.505 (0.463); NOL = 0.259-0.291 (0.276); NOH = 0.129-0.167 (0.154); PEH = 0.249-0.285 (0.275); PPL = 0.208-0.261 (0.241); PPH = 0.244-0.281 (0.271); PW = 0.510-0.590 (0.558); SBPA = 0.200-0.233 (0.217); SPTI = 0.257-0.339 (0.295); PEW = 0.156-0.182 (0.173); PNW = 0.266-0.334 (0.308); PPW = 0.257-0.310 (0.290); HFL = 0.858-0.997 (0.939); HFWmax = 0.180-0.203 (0.195); HFWmin = 0.054-0.073 (0.068); CS = 1.126-1.232 (1.206); ES = 0.278-0.312 (0.303); SI = 101-108 (104); OI = 25; CI = 87-89 (88); WLI = 151-157 (155); SBI = 26-30 (28); PSI = 31-35 (33); PWI = 160-172 (167); PLI = 179-215 (193); NI = 162-201 (180); PNWI = 164-193 (178); NLI = 53-66 (60); FI = 270-333 (290).

In full-face view, head subquadrate, longer than broad (CI 87-89). 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 flat medially. Antennal scapes moderately long: when fully retracted, surpassing the posterior margin of the head capsule by about half the maximum width of the antennal scape (SI 101-108). 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 short: extending past the antennal toruli by about one and a half times the maximum width of the antennal scape. Compound eyes 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 weakly concave medially but rounding evenly into the lateral margins.

In profile view, compound eyes ovular and moderately large (OI 25), with 15 ommatidia in longest row. Pronotal declivity indistinct, neck and anterior face of pronotum forming a ~120° angle. Mesosoma very weakly sinuate: promesonotum weakly convex from where it joins the pronotal neck to the weakly impressed mesometanotal sulcus; metanotum very weakly convex; propodeum slightly depressed below the level of the promesonotum, and very weakly convex. Promesonotal suture extending from the posterior margin of the procoxal insertion to the mesothoracic spiracle, which is well developed, then continuing 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 the poorly developed metathoracic spiracle, which is nearly indistinguishable against the ground sculpture; continuing dorsally as a faint impression to the anterior margin of the metanotum. Propodeal spiracle well developed, directed posterolaterally, and separated from the propodeal declivity by about three and a half spiracle diameters. Propodeal spines moderately well developed and moderately long (PSI 31-35), about as long as the propodeal declivity, flared at the base, straight, and acute. Propodeal declivity weakly concave, forming a rounded ~95° 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 179-215), without tubercles anterodorsally. Subpetiolar process in the form of a minute, acute, triangular tooth; ventral margin of petiole weakly bulging posterior to it. Petiolar peduncle very long: comprising about three quarters the total length of the petiole. Petiolar node erect and squamiform: transition between peduncle and node marked by a rounded angle of ~130°; anterior face forming a sharp ~70° angle with the posterior face; 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 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 not visible. Metanotum delineated anteriorly and posteriorly bye weak sulci and a disruption in ground sculpture. Propodeal spines narrowly approximated basally and weakly diverging apically, their apices separated from each other by about their length, the negative space between them "U" shaped. Petiolar peduncle with spiracles weakly protruding past the lateral margins. Petiolar node, when viewed posterodorsally, trapezoidal: broader apically than basally; node broader than the peduncle and the caudal cylinder. Postpetiole narrow (PWI 160-172) and campaniform. Anterior margin of the postpetiole convex and evenly rounds into the lateral margins; lateral margins parallel to each other; posterior corners narrowly rounded; posterior margin flat. Metafemur moderately to strongly incrassate (FI 270-333).

Sculpture: median clypeal carina present, extending posteriorly nearly to the frontal triangle, and flanked on either side by three irregular carinae. Lateral clypeal lobes with additional, weaker carinae; ground sculpture weakly areolate. Antennal scapes finely areolate. Cephalic dorsum densely areolate, with coarse rugose sculpture overlying the ground sculpture. Lateral surfaces of head sculptured similarly to the dorsum. Ventral surface of head shining, with weaker areolae and costulae. Pronotal neck areolate. Anterior face of pronotum coarsely areolate; lateral face coarsely costate. Lateral face of meso- and metapleurae coarsely rugose over weak areolate sculpture. Propodeal declivity finely strigulate. Dorsal surface of mesosoma weakly areolate, with rugose sculpture overlying the ground sculpture. Femora weakly areolate. Petiole predominantly weakly areolate, with anterior and posterior faces of node shining through very weak areolate sculpture. Postpetiole predominantly smooth and shining, with ventrolateral surface and posterior quarter finely areolate. First gastral tergite and sternite smooth and shining, without spectral iridescence.

Setae: antennal scapes and funiculi with moderately long, subdecumbent pilosity. Dorsum of the head, pronotum, waist segments, and gaster with abundant, suberect, tapering, flexuous setae, the longest of which are slightly longer than the length of the compound eye and are directed toward the midline of the body. The head bears ~40, mesosoma ~40, petiole ~6, postpetiole ~18, and first gastral tergite ~44 setae. Pubescence present over the entire body, which is nearly as long as the setae.

Color: head and mesosoma predominantly dark brown. Antennae, mandibles, pronotal neck, legs, and basal two thirds of gastral sclerites (excluding the first gastral sclerites) testaceous. Sting testaceous yellow.

Type Material
Prebus (2021) - Temnothorax longicaulis stat. nov., nom. nov. - Macromischa salvini obscurior: Syntype workers. Volcan de Chiriqui, Panama. Types assumed lost. One worker here designated neotype.

Neotype worker: COSTA RICA: Puntarenas: 4 km SSE San Vito, 8.783333_N 82.966667_W, 1,200 m, 18 March 1990, P.S. Ward#10564-2, second-growth rainforest, on low vegetation CASENT0758334, top specimen on pin).

Paraneotype worker: same pin as neotype (bottom specimen on pin) [MHNG].Paraneotype worker: same pin as neotype (bottom specimen on pin) [MHNG].

Etymology
Replacement name for Temnothorax obscurior, which is occupied by a species from North Africa. From the Latin ʻlongus' (=long) + ʻcaulis' (=stalk or stem of plant), in reference to the elongate petiolar peduncle of this species.