Temnothorax annexus

Wheeler (1931) reports this species was collected from the epiphytic plant Tillandsia circinnata.

Identification
Prebus (2021) – A member of the annexus group of the Temnothorax salvini clade. Temnothorax annexus can be separated from all other species in the salvini clade by the following character combination: subdecumbent setae present on gula; metanotal groove absent; propodeum bearing erect setae; propodeum not depressed; propodeal spines short, slightly shorter than the propodeal declivity (PSI 28-29); hind femora strongly incrassate (FI 338-349); petiole with a moderately long peduncle: peduncle comprising about half of the total length of the petiole; petiolar node erect and subquadrate, not overhanging the caudal cylinder; postpetiole narrow (PWI 169-173); first gastral tergite smooth and shining; integument testaceous; dorsum of head, mesosoma, waist segments and gaster with erect, short, blunt-tipped setae; legs without erect setae.

Similar species: Temnothorax andersoni, Temnothorax andrei, Temnothorax aureus, Temnothorax aztecoides, Temnothorax aztecus, Temnothorax carinatus, Temnothorax casanovai, Temnothorax cokendolpheri, Temnothorax goniops, Temnothorax nitens, Temnothorax paraztecus, Temnothorax punctaticeps, Temnothorax rugosus, Temnothorax subditivus (light form), Temnothorax tenuisculptus, Temnothorax terrigena, Temnothorax wardi., and species of the annexus, fuscatus, and silvestrii groups. Temnothorax annexus can be separated from T. andersoni, T. andrei, T. aztecoides, T. aztecus, T. carinatus, T. cokendolpheri, T. goniops, T. nitens, T. terrigena, T. wardi, and species of the silvestrii group by the strongly incrassate hind femora (FI >330). Furthermore, it can be distinguished from T. andersoni, T. andrei, T. aztecoides, T. aztecus, T. carinatus, T. cokendolpheri, T. goniops, T. nitens, T. terrigena, and the silvestrii group by the anterior clypeal margin, which is emarginate in T. annexus. The absence of erect, long, tapering setae on the body will separate T. annexus from T. aztecoides, T. aztecus, and T. paraztecus, while the erect, subquadrate petiolar node differentiates T. annexus from the fuscatus group, T. punctaticeps, T. rugosus, T. subditivus, and nearly all other species listed above. To separate T. annexus from other members of the annexus group, look for the following character combination: a continuous dorsal margin of the mesosoma in profile (propodeum not depressed as in T. tenuisculptus); decumbent setae on the gular region (Temnothorax arbustus, Temnothorax balnearius, and Temnothorax obtusigaster have erect setae); propodeal spines slightly shorter than the propodeal declivity (PSI ~ 29), pedunculate petiole, with the peduncle comprising about half the total petiole length, and heavily sculptured, predominantly areolate-rugose head and mesosoma will all distinguish T. annexus from Temnothorax quercicola

Wheeler (1931) - This singular ant somewhat resembles M. azteca and salvini, but is really very different. In habitus it is so much like certain species of Leptothorax, especially those of the rottenbergi group, that I should have placed it in that genus but for its more conspicuously incrassated femora.

Distribution
The only known specimens are from the type collection, which were found in a mid elevation site of the Southern Sierra Madre in South-Central Mexico.

Distribution based on Regional Taxon Lists
Neotropical Region: Mexico.

Biology
Prebus (2021) - Known only from the type series, which was collected from Tillandsia circinnata epiphytes near Cuernavaca, Morelos, Mexico by Elizabeth Skwarra. Temnothorax annexus has close relatives in Baja California, Arizona, and Sonora that nest in dead vegetation, including live branches of oak trees. It is morphologically convergent with, but not particularly closely related to, members of the rottenbergii group of the Palearctic, or the sallei clade of southern North America, Central America, and the Greater Antilles (Baroni Urbani, 1978; Fontenla Rizo, 2000; Prebus, 2017).

Nomenclature

 * annectens. Macromischa annectens Wheeler, W.M. 1931b: 11 (w.) MEXICO. [Junior secondary homonym of annectens Wheeler, W.M., above.] Replacement name: annexus Baroni Urbani, 1978b: 421.
 *  annexus. Leptothorax annexus Baroni Urbani, 1978b: 421. Replacement name for annectens Wheeler, W.M. 1931b: 11. [Junior secondary homonym of annectens Wheeler, W.M. 1903c: 242.] Combination in Temnothorax: Bolton, 2003: 271.

Worker
(Wheeler, 1931; annectens) Length about 3.7 mm.

Head subrectangular, slightly broader behind than in front, with broadly rounded posterior corners and nearly straight posterior border. Eyes moderately large and convex, at the middle of the sides. Mandibles rather small and flat, with a large apical and four smaller basal teeth. Clypeus short, convex in the middle behind, its anterior border sinuate in the middle and on each side so that it appears somewhat bilobed. Frontal area triangular, rather indistinct. Frontal carinae short, diverging posteriorly. Antennal scapes reaching to the posterior corners of the head; first funicular joint as long as the three succeeding joints together; joints 2-7 small, broader than long, 8 as long as broad; the three terminal joints forming a very distinct club, as long as the remainder of the funiculus and with the two basal joints subequal and together shorter than the last joint. Thorax long and narrow, fully three times as long as broad, somewhat broader through the pronotum than through the parallel-sided mesoepinotum; pleurae flattened; dorsal surface in profile nearly straight and horizontal, without mesoepinotal impression; base and declivity of epinotum subequal, the latter perpendicular and concave; the spines stout at the base, laterally compressed, with blunt tips, longer than their distance apart at the base, but shorter than the epinotal declivity, directed backward and outward and very slightly curved downward. Peduncle of petiole with a minute anteroventral tooth, nearly as long as the node, which is somewhat cuboidal and constricted behind, in profile with steeply sloping anterior, horizontal superior and perpendicular posterior surface; seen from above, it is as long as broad, semicircularly rounded anteriorly, with straight posterior border. Postpetiole l 2/3 times as broad as the petiolar node and about 1 1/2 times as broad as long, rounded-trapezoidal, slightly broader behind than in front, convex and rounded above. Gaster 'rather large, broadly elliptical, first segment with truncated, nearly straight anterior border; sting long. Legs stout; all the femora, and especially the hind pair, conspicuously incrassated in the middle.

Opaque; venter, coxae, legs and antennal scapes feebly shining, or glossy. Mandibles finely longitudinally striated. Clypeus longitudinally rugulose, most distinctly on the sides. Head densely punctate above, longitudinally reticulate-rugose, its sides and the sides of the thorax merely reticulate-rugose, the dorsal surface of the latter longitudinally but more vermiculately rugose, the pronotum much more coarsely than the mesoepinotum. Epinotal declivity smooth but dull. Petiolar node indistinctly reticulate-rugose above, postpetiole coarsely and densely, and dorsal surface of first gastric segment more distinctly, scapes and legs more finely and indistinctly reticulate or shagreened.

Hairs on the body yellowish, short, stout and obtuse (as in Leptothorax), not very abundant and confined largely to the dorsal surface; pubescence very short and appressed, distinct on the antennae, almost absent on the legs.

Ferruginous red; mandibles, antennae, coxae, legs, petiolar peduncle and terminal gastric segments paler, dull ferruginous yellow; first gastric segment with a poorly defined dark brown fascia posteriorly. Mandibular teeth black.

Prebus (2021) - (n = 3): SL = 0.759-0.766 (0.762); FRS = 0.261-0.302 (0.284); CW = 0.891-0.917 (0.904); CWb = 0.778-0.826 (0.807); PoOC = 0.350-0.378 (0.367); CL = 0.947-0.993 (0.973); EL = 0.218-0.238 (0.226); EW = 0.163-0.182 (0.173); MD = 0.236-0.262 (0.245); WL = 1.304-1.395 (1.345); SPST = 0.361-0.408 (0.387); MPST = 0.433-0.435 (0.434); PEL = 0.505-0.529 (0.514); NOL = 0.299-0.313 (0.304); NOH = 0.185-0.204 (0.198); PEH = 0.322-0.344 (0.336); PPL = 0.229-0.248 (0.241); PW = 0.572-0.622 (0.590); SBPA = 0.243-0.290 (0.272); SPTI = 0.329-0.340 (0.333); PEW = 0.230-0.234 (0.233); PNW = 0.250-0.273 (0.260); PPW = 0.389-0.405 (0.400); HFL = 0.835-0.850 (0.841); HFWmax = 0.251-0.274 (0.266); HFWmin = 0.072-0.081 (0.078); CS = 1.252-1.323 (1.294); ES = 0.300-0.329 (0.312); SI = 92-98 (94); OI = 23-25 (24); CI = 82-84 (83); WLI = 163-169 (167); SBI = 30-37 (34); PSI = 28-29 (29); PWI = 169-173 (172); PLI = 206-221 (213); NI = 147-162 (154); PNWI = 107-117 (112); NLI = 59; FI = 338-349 (342).

In full-face view, head subquadrate, longer than broad (CI 82-84). 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 moderately long: when fully retracted, just reaching the posterior margin of the head capsule (SI 92-98). 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 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 weakly emarginate medially but rounding evenly into the lateral margins.

In profile view, compound eyes ovular and moderately large (OI 23-25), 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 propodeal spines, nearly flat. 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 well developed, directed posterolaterally, and separated from the propodeal declivity by about four spiracle diameters. Propodeal spines moderately well developed and moderately long (PSI 28-29), about as long as the propodeal declivity, flared at the base, downcurved, and blunt. Propodeal declivity weakly concave, forming a rounded ~110° 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 206-221), with weakly developed tubercles anterodorsally. Subpetiolar process in the form of a small, blunt tooth; ventral margin of petiole flat posterior to it. Petiolar peduncle moderately long: comprising about half 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 ~90° angle, which forms a ~100° angle with the caudal cylinder. Postpetiole flat anteriorly, bulging slightly anterodorsally before flattening posterodorsally; weakly lobed ventrally.

In dorsal view, humeri moderately well 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 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 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 not protruding past the lateral margins. Petiolar node nearly evenly ovular, but posterior margin flattened; node broader than the peduncle, and evenly grading into the caudal cylinder, which is the same width as the node. Postpetiole narrow (PWI 169-173) and subquadrate. Anterior margin of the postpetiole flat and evenly rounds into the lateral margins, which diverge slightly to the rounded posterior corners; posterior margin flat. Metafemur strongly incrassate (FI 338-349).

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 shining through weak areolae. Antennal scapes areolate. Cephalic dorsum areolate, with coarse rugae over the ground sculpture; concentric costulae surrounding the antennal insertions; overlying sculpture primarily costate between the frontal carinae. Lateral surfaces of head areolate, with coarse rugae over the ground sculpture. Ventral surface of head smooth and shining anteromedially, but otherwise weakly areolate-costulate. Pronotal neck areolate. Lateral surfaces mesosoma areolate with coarse rugae over the ground sculpture, but with longitudinal rugae stronger than transverse rugae. Propodeal declivity areolate-rugulose. Dorsal surface of mesosoma sculptured similarly to the lateral surface, but stronger longitudinal rugae restricted to the pronotum. 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 the dorsal and posterior faces of the node. Postpetiole uniformly areolate, with weak rugulose sculpture on the lateral faces. First gastral tergite areolate, but with sculpture becoming weaker 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 half the width of the compound eye. The head bears ~18, mesosoma ~26, petiole 10, postpetiole ~16, 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 testaceous, with apex of mandibles dark brown.

Type Material
Described from three specimens taken by Dr. Skwarra at Cuernavaca, Morelos, Mexico, nesting in an air-plant, Tillandsia circinnata.

Prebus (2021) - Macromischa annectens: Syntype workers. Cuernavaca, Mexico. One worker here designated lectotype.

Lectotype worker: MEXICO: Morelos: Cuernavaca, 26 June 1929, E. Skwarra #Z867/Sk., ex Tillandsia circinnata, 1 worker (M.C.Z. co-type 2-3 16359, MCZENT00561747, bottom specimen on pin).

Paralectotype workers: same pin as lectotype, 1 worker (top specimen on pin); same data as lectotype, 2 teneral workers (M.C. Z. co-type 4-5 16359, MCZENT00561746) [MCZC].

Etymology
In the original description, Wheeler (1931) states that this species, which he placed in Macromischa, nonetheless bears many features of the rottenbergii group of the Palearctic. Presumably ʻannectens' (= connected) from Greek refers to the implied link between these taxa.

References based on Global Ant Biodiversity Informatics

 * Brandao, C.R.F. 1991. Adendos ao catalogo abreviado das formigas da regiao neotropical (Hymenoptera: Formicidae). Rev. Bras. Entomol. 35: 319-412.
 * Kempf, W.W. 1972. Catalago abreviado das formigas da regiao Neotropical (Hym. Formicidae) Studia Entomologica 15(1-4).
 * Vásquez-Bolaños M. 2011. Lista de especies de hormigas (Hymenoptera: Formicidae) para México. Dugesiana 18: 95-133