Temnothorax quercicola

A monogynous species with small colonies that are typically less than 70 workers.

Identification
Prebus (2021) – A member of the annexus group of the Temnothorax salvini clade. Temnothorax quercicola can be separated from other species in the salvini clade by the following character combination: setae absent on gula; metanotal groove absent; propodeum not depressed; propodeum bearing erect setae; propodeal spines shorter than the propodeal declivity (PSI 22-30); hind femora strongly incrassate (FI 314-388); petiolar peduncle comprising about a third of the total length of the petiole; petiolar node erect and subquadrate, not overhanging the caudal cylinder in profile view; postpetiole narrow (PWI 164-183); first gastral tergite weakly areolate; integument yellow; dorsum of head, mesosoma, waist segments and gaster with erect, short, blunt-tipped setae; legs without erect setae.

Similar species: Temnothorax anaphalantus, Temnothorax andrei, Temnothorax caguatan, Temnothorax carinatus, Temnothorax cokendolpheri, Temnothorax nitens, Temnothorax pilicornis, Temnothorax pseudandrei, Temnothorax rugosus, Temnothorax subditivus, Temnothorax tenuisculptus, Temnothorax wardi, species of the silvestrii group, and other members of the annexus group. Temnothorax quercicola can be separated from all of the above species, except for T. anaphalantus, T. rugosus, T. wardi and the other members of the annexus group, by the medially emarginate anterior clypeal margin. Furthermore, it can be distinguished from T. caguatan by the 12-segmented antennae, which are 11-segmented in the latter. The erect, subquadrate petiolar node of Temnothorax quercicola contrasts with the node of T. subditivus, which is squamiform, and the nodes of T. nitens, T. rugosus and T. wardi, which are cuneiform to subcuneiform. The dorsal margin of the mesosoma is continuous in T. quercicola, as opposed to sinuate, with a depressed propodeum in T. tenuisculptus. The antennal scapes with subdecumbent setae contrast with those of T. pilicornis, which has suberect setae. The massively incrassate hind femora will separate T. quercicola from all species listed above (except for T. subditivus, T. tenuisculptus, T. rugosus, and other members of the annexus group), which have less incrassate hind femora (FI 314-388 in T. quercicola vs. < 300). Within the annexus group, the following characters distinguish T. quercicola from its close relatives: gula without erect setae, as opposed to present but decumbent (Temnothorax annexus) or present and erect (Temnothorax arbustus, Temnothorax balnearius, and Temnothorax obtusigaster); petiolar peduncle short, comprising about a third of the total petiole length, vs. comprising about half in T. annexus; propodeal spines shorter than the propodeal declivity, vs. about as long as the propodeal declivity in T. annexus.

Temnothorax quercicola has a long history of being misidentified as T. silvestrii, a co-occurring, morphologically convergent member of the distantly related sallei clade. Temnothorax quercicola most obviously differs from T. silvestrii by the incrassate femora, but the notched anterior margin of the clypeus and the blockier head shape are equally telling characters.

Distribution
Temnothorax quercicola is known from multiple collections at mid elevations in the sky islands of southern Arizona and Sonora.

Distribution based on Regional Taxon Lists
Nearctic Region: United States. Neotropical Region: Mexico.

Biology
Prebus (2021) - This species appears to preferentially nest within hollow cavities of larger limbs of Quercus emoryi or Q. grisea, eschewing small twigs (Creighton, 1953). Colonies are monogynous and small, with 50- 70 workers (Creighton, 1953).

Nomenclature

 * . Temnothorax quercicola Prebus, 2021: 113, figs. 95E, 100 (w.dq.m.) U.S.A. (Arizona).

Temnothorax quercicola has a long history of being misidentified as T. silvestrii, a co-occurring, morphologically convergent member of the distantly related sallei clade. Interestingly, in an article detailing the ʻrediscoveryʼ of T. silvestrii (which was in fact T. quercicola), Creighton (1953) noted that specimens were sent to Heinrich Kutter at the NHMB to compare with types of T. silvestrii (see CASENT0913000). Kutter detailed a number of differences between the specimens of T. quercicola and the type, which he thought justified separating them from T. silvestrii (correctly, as it turns out). Unfortunately, Creighton dismissed these morphological disparities and stated that the type specimen fell within the range of observed variation among nests.

Worker
Prebus (2021) - (n = 8): SL = 0.631-0.696 (0.665); FRS = 0.255-0.281 (0.268); CW = 0.786-0.870 (0.837); CWb = 0.713-0.786 (0.747); PoOC = 0.301-0.346 (0.323); CL = 0.854-0.916 (0.883); EL = 0.186-0.244 (0.212); EW = 0.138-0.168 (0.155); MD = 0.191-0.239 (0.214); WL = 1.101-1.219 (1.161); SPST = 0.250-0.345 (0.295); MPST = 0.334-0.420 (0.373); PEL = 0.347-0.450 (0.395); NOL = 0.206-0.251 (0.224); NOH = 0.161-0.181 (0.172); PEH = 0.298-0.348 (0.324); PPL = 0.211-0.258 (0.241); PW = 0.508-0.569 (0.542); SBPA = 0.205-0.247 (0.226); SPTI = 0.252-0.305 (0.273); PEW = 0.195-0.22 (0.209); PNW = 0.193-0.229 (0.212); PPW = 0.338-0.381 (0.358); HFL = 0.671-0.771 (0.731); HFWmax = 0.220-0.248 (0.232); HFWmin = 0.059-0.071 (0.067); CS = 1.145-1.242 (1.189); ES = 0.255-0.327 (0.290); SI = 84-92 (89); OI = 22-26 (24); CI = 83-86 (85); WLI = 151-158 (155); SBI = 29-32 (30); PSI = 22-30 (25); PWI = 164-183 (172); PLI = 139-185 (165); NI = 116-144 (130); PNWI = 95-166 (109); NLI = 51-63 (57); FI = 314-388 (349).

In full-face view, head subquadrate, longer than broad (CI 83-86). 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 emarginated medially. Antennal scapes short: when fully retracted, failing to reach the posterior margin of the head capsule by about the maximum width of the antennal scape (SI 84-92). 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 strongly 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 22-26), with 13 ommatidia in longest row. Pronotal declivity distinct: dorsal margin of anterior face of pronotum marked by a carina; neck and anterior face of pronotum forming a ~120° angle. Mesosoma very weakly convex from where it joins the pronotal declivity to 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. 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 five spiracle diameters. Propodeal spines short (PSI 22-30), shorter than the propodeal declivity, slightly flared at the base, thin, straight, and acute. Propodeal declivity straight, forming a rounded ~100° angle with the base of the propodeal spines. Propodeal lobes rounded and weakly developed, but dorsum slightly angulate. Metapleural gland bulla small, extending from the metacoxal insertion halfway to the propodeal spiracle. Petiole moderately long (PLI 139-185), with tubercles anterodorsally. Subpetiolar process in the form of a small, blunt, triangular tooth which grades evenly into the ventral petiole margin posteriorly; ventral margin of petiole weakly concave posterior to it. Petiolar peduncle short: comprising about a third of the total petiole length. Petiolar node robust, erect, and subquadrate: transition between peduncle and node marked by a rounded angle of ~120°; anterior face forming a ~110° angle with the dorsal face, which is weakly convex, nearly flat; dorsal face meeting the posterior face at a rounded ~90° angle; posterior face forms a ~100° angle with the caudal cylinder. Postpetiole convex anteriorly, bulging slightly anterodorsally before flattening posterodorsally; weakly lobed ventrally.

In dorsal view, humeri weakly developed: evenly rounded and barely 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 represented by a weak sulcus. 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 weakly diverging apically, their apices separated from each other by slightly more than their length, the negative space between them "U" shaped. Petiolar peduncle with spiracles weakly protruding past the lateral margins. Petiolar node nearly ovular, but posterior margin flattened; node broader than the peduncle, and evenly grading into the caudal cylinder, which is slightly narrower than the node. Postpetiole narrow (PWI 164-183) and subquadrate. Anterior margin of the postpetiole weakly convex, nearly flat, and meets the lateral margins at a ~90° angle; lateral margins parallel to each other; posterior corners rounded; posterior margin flat. Metafemur incrassate (FI 314-388).

Sculpture: median clypeal carina present, extending posteriorly to the frontal triangle, and flanked on either side by two weaker carinae. Lateral clypeal lobes with additional, weaker carinae; ground sculpture shining through weak areolae. Antennal scapes areolate. Cephalic dorsum areolate, with fine rugae over the ground sculpture; concentric costulae surrounding the antennal insertions; overlying sculpture becoming costate between the frontal carinae. Lateral surfaces of head areolate, with rugae over the ground sculpture. Ventral surface of head smooth and shining anteromedially, but otherwise weakly areolate with weak costulae. Pronotal neck weakly areolate. Lateral surfaces mesosoma areolate, with costulae over the ground sculpture; region between the propodeal spiracle and propodeal spines areolate, without costulae. Propodeal declivity areolate. Dorsal surface of mesosoma predominantly areolate, with fine costulae on the pronotum and rugae on the rest of the mesosoma. Femora finely, densely areolate. Petiole uniformly areolate; a weak carina present laterally, extending longitudinally from the petiolar spiracle to the caudal cylinder; weak rugae on all faces of the node. Postpetiole uniformly areolate, with rugulose sculpture on the lateral faces. First gastral tergite weakly, finely areolate, with sculpture weakening posteriorly; without spectral iridescence. First gastral sternite smooth and shining, without spectral iridescence.

Setae: antennal scapes and funiculi with short, adpressed 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 ~38, mesosoma ~38, petiole 10, postpetiole ~18, and first gastral tergite ~80 setae. Short, sparse pubescence present over the entire body, but difficult to detect against the densely sculptured integument.

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

Queen
Prebus (2021) - (n = 1): SL = 0.783; FRS = 0.386; CW = 1.127; CWb = 1.022; PoOC = 0.366; CL = 1.086; EL = 0.354; EW = 0.297; MD = 0.220; WL = 2.001; SPST = 0.440; MPST = 0.495; PEL = 0.567; NOL = 0.293; NOH = 0.254; PEH = 0.538; PPL = 0.333; PW = 1.154; SBPA = 0.496; SPTI = 0.503; PEW = 0.312; PNW = 0.356; PPW = 0.591; HFL = 0.942; HFWmax = 0.282; HFWmin = 0.100; CS = 1.565; ES = 0.503; SI = 77; OI = 32; CI = 94; WLI = 196; SBI = 49; PSI = 22; PWI = 189; PLI = 170; NI = 115; PNWI = 114; NLI = 52; FI = 282.

In full-face view, head subquadrate, slightly longer than broad (CI 94). Mandibles densely 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 emarginated 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 77). Antennae 12-segmented; antennal club 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 strongly protruding past the lateral margins of the head capsule. Lateral margins of head convex behind the compound eyes, but parallel to each other between the mandibular insertions and the compound eyes. Posterior head margin concave medially, rounding evenly into the lateral margins.

In profile view, compound eyes ovular and large (OI 32), with 22 ommatidia in longest row. Mesoscutum rounded evenly anteriorly, covering the dorsal surface of the pronotum, and flat dorsally. Mesoscutellum on the same plane as the mesoscutum and flat dorsally. 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 short and stout (PSI 22), about half as long as the propodeal declivity, tapering evenly from the base, directed posterodorsally, triangular, and blunt. Propodeal declivity straight and flat, forming a rounded ~100° angle with the base of the propodeal spines. Propodeal lobes rounded, but slightly angulate dorsally. Metapleural gland bulla moderately large, extending from the metacoxal insertion two thirds of the way to the propodeal spiracle. Petiole moderately long (PLI 170), with weakly developed tubercles anterodorsally. Subpetiolar process in the form of a small, blunt, triangular tooth, which grades evenly into the ventral margin of the petiole posteriorly. Petiolar peduncle short: comprising about a third of the total petiole length. Petiolar node robust and erect, subquadrate: transition between peduncle and node an evenly rounded ~120° angle; anterior face forming a rounded ~90° angle with the dorsal face, which weakly convex; dorsal face meeting the posterior face at a ~110° angle; posterior face forms a ~120° angle with the caudal cylinder. Postpetiole flat anteriorly, bulging slightly anterodorsally before it transitions into the flattened posterodorsal face; ventral surface weakly 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, but slightly narrowed anterior to them. Petiolar node subquadrate, anterior margin slightly broader than posterior margin. Petiolar node tapering apically, slightly wider than the peduncle, and evenly grading into the caudal cylinder, which is narrower than the node. Postpetiole narrow (PWI 189), anteroposteriorly compressed, and subquadrate. Anterior margin of postpetiole flat, with corners marked by rounded ~90° angles as it transitions to the lateral margins; lateral margins parallel to each other; posterior corners rounded; posterior margin flat. Metafemur moderately incrassate (FI 282).

Sculpture: median clypeal carina present, extending from the anterior margin nearly to frontal triangle, and flanked by multiple weaker, indistinct carinae. Lateral clypeal lobes with additional weaker carinae; ground sculpture smooth and shining. Antennal scapes finely areolate-costulate. Cephalic dorsum areolate, with rugose sculpture overlying the ground sculpture; concentric costulae surround the antennal insertions. Lateral surfaces of head areolate, with costate sculpture overlying the ground sculpture; sculpture becoming rugose between the compound eye and mandibular insertion. Ventral surface of head smooth and shining medially, with weak areolate-rugulose sculpture laterally and posteriorly. Pronotal neck areolate. Anterior face of pronotum weakly areolate. Lateral surfaces of the mesosoma sculptured similarly to the dorsum of the head; anterior half of anepisternum areolate, without overlying rugose sculpture. Propodeal declivity weakly areolate- strigulate. Mesoscutum with costulate sculpture over finely areolate ground sculpture; a longitudinal strip of very weakly areolate sculpture present medially. Mesoscutellum smooth and shining, with weak costulae on the lateral margins. Metanotum finely areolate. Propodeum areolate, with fine strigulae. Femora shining through weak areolate sculpture. Petiole uniformly areolate; a weak carina present laterally, extending longitudinally from the petiolar spiracle to the caudal cylinder; weak reticulate rugae on all faces of the node. Postpetiole uniformly areolate, with weak rugose sculpture on the lateral faces. First gastral tergite and sternite predominantly smooth and shining, with weak spectral iridescence; base of first gastral tergite with traces of weak areolate sculpture.

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

Color: predominantly yellow, with masticatory margin of the mandibles and wing bases dark brown.

Male
Prebus (2021) - (n = 1): SL = 0.272; FRS = 0.176; CW = 0.792; CWb = 0.677; PoOC = 0.242; CL = 0.619; EL = 0.341; EW = 0.295; MD = 0.043; WL = 1.134; SPST = n/a; MPST = 0.352; PEL = 0.282; NOL = 0.174; NOH = 0.076; PEH = 0.224; PPL = 0.196; PW = 0.762; SBPA = n/a; SPTI = n/a; PEW = 0.180; PNW = 0.212; PPW = 0.325; HFL = 0.774; HFWmax = 0.137; HFWmin = 0.063; CS = 0.987; ES = 0.489; SI = 40; OI = 50; CI = 109; WLI = 168; SBI = n/a; PSI = n/a; PWI = 181; PLI = 144; NI = 229; PNWI = 118; NLI = 62; FI = 217.

In full-face view, head subovate, slightly broader than long (CI 109). Mandibles very weakly striate, shining, 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 very short: when fully retracted, failing to reach the posterior margin of the head capsule by about five times the maximum width of the antennal scape (SI 39). Antennae 13- segmented; antennal club composed of four 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 and a half the maximum width of the antennal scape. Compound eyes strongly protruding past the lateral margins of the head capsule. Lateral margin of head convex behind the compound eyes; margin between the mandibular insertions and the anterior margin of the compound eye straight. Posterior head margin flat medially, rounding evenly into the lateral margins.

In profile view, compound eyes ovular and large (OI 50), with 24 ommatidia in the longest row. Mesoscutum bulging anteriorly, covering the dorsal surface of the pronotum, convex dorsally. Mesoscutellum on the same plane as the mesoscutum, convex dorsally. Posterior margin of metanotum extending beyond the posterior margin of the mesoscutellum. Propodeum weakly depressed, convex dorsally, and separated from the base of the propodeal angles by a deep sulcus. Propodeal spiracle moderately well developed, directed posterolaterally, and separated from the propodeal declivity by about four spiracle diameters. Propodeal spines absent but represented by blunt angles. Propodeal lobes rounded and weakly developed. Metapleural gland bulla very small, extending a quarter of the way between the insertion of the metacoxa and the propodeal spiracle. Petiole short (PLI 144), with weak tubercles anterodorsally. Subpetiolar process absent; ventral margin of petiole bulging slightly. Petiolar peduncle short: comprising about a third of the total petiole length. Petiolar node low and dorsally truncated, nearly cuneiform; the convergence of the anterior and dorsal faces marked by a ~110° angle; dorsal face very short, meeting the posterior face at a ~100° angle. Postpetiole flat anteriorly, rounded and slightly bulging anterodorsally, flattened posterodorsally, and concave ventrally.

In dorsal view, mesoscutum covering pronotum. Petiolar peduncle with spiracles slightly protruding past the lateral margins; transversely constricted anterior to them. Petiolar node slightly wider than the peduncle and the caudal cylinder; subquadrate when viewed dorsally. Postpetiole narrow (PWI 181) and subquadrate. Anterior margin of postpetiole weakly convex, with the anterior corners evenly rounding into the lateral margins; lateral margins parallel to each other; posterior margin of postpetiole flat. Metafemur not incrassate (FI 217).

Sculpture: median clypeal lobe with multiple indistinct carinae. Antennal scapes shining, with traces of weak areolate sculpture. Dorsum of head areolate, with weak, fine costulae between the frontal carinae. Lateral surface of head areolate, with weak, fine costulae posterior to the compound eye. Ventral surface of head weakly areolate, with weak, fine costulae. Pronotal neck very weakly areolate. Anterior face of pronotum weakly areolate. Lateral surface of pronotum predominantly areolate, with an anterior patch of smooth and shining sculpture. Katepisternum smooth and shining. Anepisternum predominantly smooth and shining, with weak areolate sculpture on the posterior half. Metapleuron and lateral face of propodeum areolate. Propodeal declivity weakly, finely transversely rugose. Dorsally, mesoscutum weakly areolate along the Mayrian furrows. Mesoscutellum predominantly smooth and shining, with traces of weak areolate sculpture laterally. Femora smooth and shining, with traces weak areolate sculpture. Petiole weakly areolate laterally, but smooth and shining dorsally. 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 short, adpressed pilosity. Dorsum of the head, pronotum, waist segments, and gaster with moderately abundant, erect, blunt-tipped setae, the longest of which are about a quarter of the width of the compound eye. Short, sparse pubescence present over the entire body, but difficult to detect against the densely sculptured integument.

Color: predominantly yellow, with masticatory margin of the mandibles and interior of the ocellar triangle testaceous brown.

Type Material
Prebus (2021) - Holotype worker: U.S.A.: Arizona: Pima County: Baboquivari Mountains, Brown Cañon, 1,220 m, 19 September 1951, W.S. Creighton #245, in Quercus emoryi (LACMENT323216, middle specimen on pin).

Paratype workers and gyne: U.S.A.: Arizona: same pin as holotype, 1 worker, 1 dealate gyne (top and bottom specimens on pin, respectively) [LACM]; same data as previous, 4 workers (CASENT0172599) [LACM] 3 workers (FMNHINS0000115817).

Etymology
Prebus (2021) - Behavioural, from the Latin ʻquercus' (= oak tree) + ʻcolus' (= dweller) in reference to the well-established nesting preference of this species.

Determination Clarifications
Prebus (2021) - Temnothorax quercicola has a long history of being conflated with T. silvestrii, to the extent that Creighton (1953) described the male and gyne of T. quercicola as Temnothorax silvestrii.

Allred (1982) reports T. silvestrii, which this species is often confused with, from Box Elder, Utah; I have not personally observed this collection, so I have excluded it from the range.