Temnothorax annexus ( Baroni Urbani, 1978 )

Prebus, Matthew M., 2021, Taxonomic revision of the Temnothorax salvini clade (Hymenoptera: Formicidae), with a key to the clades of New World Temnothorax, PeerJ (e 11514) 9, pp. 1-462 : 94-97

Temnothorax annexus ( Baroni Urbani, 1978)

Distribution: Fig. 95A ; worker: Fig. 96 .

Macromischa annectens Wheeler, 1931: 11 . Syntype workers. Cuernavaca, Mexico. One worker here designated lectotype.

Leptothorax annexus Baroni Urbani, 1978: 421 . Transferred to Leptothorax . Nomen novum for Leptothorax annectens (Wheeler) : 11 (nec Leptothorax curvispinosus ssp. annectens Wheeler, 1903 b: 242 ).

Temnothorax annexus (Baroni Urbani) : Bolton, 2003: 271. First combination in Temnothorax .

Type material examined: 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) [ MCZC].

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] .

Geographic range: South-Central Mexico, mid elevations of the Southern Sierra Madre ( Fig. 95A ).

Worker diagnosis: 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 (Mackay) , T. andrei (Emery) , T. aureus sp. nov., T. aztecoides sp. nov., T. aztecus , T. carinatus (Cole) , T. casanovai sp. nov., T. cokendolpheri (Mackay) , T. goniops , T. nitens (Emery) , T. paraztecus sp. nov., T. punctaticeps (Mackay) , T. rugosus , T. subditivus (light form), T. tenuisculptus , T. terrigena , T. wardi Snelling et al. , and species of the annexus , fuscatus , and silvestrii groups. Temnothorax annexus can be separated from T. andersoni , T. andrei , T. aztecoides sp. nov., 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 sp. nov., 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 sp. nov., T. aztecus , and T. paraztecus sp. nov., 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 ( T. arbustus sp. nov., T. balnearius sp. nov., and T. obtusigaster sp. nov. 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 T. quercicola sp. nov.

Worker measurements & indices (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).

Worker description: 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.

Gyne: Unknown.

Male: Unknown.

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 ‘annectens’ (= connected) from Greek refers to the implied link between these taxa.

Comments: 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).

Figures

Figure 95 Geographical and elevational distribution of the annexus group. (A) Temnothorax annexus (B) T. arbustus sp. nov. (C) T. balnearius sp. nov. (D) T. obtusigaster sp. nov. (E) T. quercicola sp. nov. Colored scale to the left of each map represents elevation in meters. Points in black represent the species named in each subfigure, while points in red represent other members of the species group. Type localities are represented by triangles, non-type localities are represented by circles. Bounding box in inset map shows location of main map. Full-size DOI: 10.7717/peerj.11514/fig-95

Figure 96 Temnothorax annexus lectotype worker (MCZENT00561747). (A) Profile view. (B) Fullface view. (C) Dorsal view. Scale bars 0.2 mm. Full-size DOI: 10.7717/peerj.11514/fig-96