Temnothorax parralensis, Prebus, 2021

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 : 345-351

Temnothorax parralensis sp. nov.

Distribution: Fig. 150A ; worker & male: Fig. 151 .

Type material examined: Holotype: MEXICO: Chihuahua: 55 km south of Parral , 1,770 m, 2 May 1953, W.S. Creighton, in Quercus grisea ( LACMENT323355 , bottom specimen on pin) [ LACM].

Paratype workers and males: same pin as holotype, 1 worker & 1 male (middle and top specimens on pin) [ LACM]; same collection data as holotype, 2 males, 1 worker (LACMENT323351) [ LACM] 1 male, 3 workers (LACMENT323352) [ MCZC] 1 male, 2 workers (LACMENT323353) [ LACM] 2 males, 1 worker (LACMENT323354) [ UCDC] 1 male, 3 workers (LACMENT323356) [ LACM] 1 male, 2 workers (LACMENT323357) [ USNM] .

Geographic range: Mid elevations in northern Mexico (Chihuahua) ( Fig. 150A ).

Worker diagnosis: Temnothorax parralensis sp. nov. can be separated from all other species in the salvini clade by the following character combination: anterior clypeal margin emarginate; metanotal groove absent; propodeum not depressed, and bearing setae dorsally; petiolar node flat dorsally; hind femora moderately incrassate; in dorsal view, postpetiole narrow, less than 1.5 times the width of the petiole; dorsum of head, mesosoma, waist segments and gaster with erect, short, blunt-tipped setae; legs without erect setae; integument predominantly testaceous.

Similar species: Temnothorax rugosus , T. tricarinatus Emery , species of the annexus and silvestrii groups. Temnothorax parralensis sp. nov. may be separated from T. tricarinatus by the moderately incrassate femora (not apparent in smaller workers), and the weakly sculptured first gastral tergite (which is smooth and shining in T. tricarinatus ). Many of the preceding characters, in combination, are shared with members of the annexus species group, which T. parralensis sp nov. is closely related to. Temnothorax parralensis sp. nov. can be separated from the species of the annexus group by the relatively narrow postpetiole (PWI <150) and the propodeal spines, which are short (PSI <22) and dorsally directed; all species in the annexus group have broader postpetioles (PWI> 150) and longer (PSI ≥ 22), posterodorsally directed propodeal spines. The areolate first gastral tergite may suggest an affiliation with the silvestrii group, but these species never have incrassated femora. The closest relative of T. parralensis sp. nov. is T. rugosus , which always has a cuneiform to subcuneiform petiolar node.

Worker measurements & indices (n = 5): SL = 0.494 –0.555 (0.518); FRS = 0.228 –0.258 (0.238); CW = 0.712 –0.771 (0.737); CWb = 0.637 –0.692 (0.659); PoOC = 0.265 –0.295 (0.284); CL = 0.760 –0.837 (0.788); EL = 0.198 –0.227 (0.211); EW = 0.147 –0.166 (0.154); MD = 0.191 –0.217 (0.206); WL = 0.939 –1.063 (1.004); SPST = 0.161 –0.219 (0.193); MPST = 0.268 –0.306 (0.290); PEL = 0.296 –0.343 (0.318); NOL = 0.147 –0.226 (0.188); NOH = 0.116 –0.140 (0.131); PEH = 0.242 –0.277 (0.257); PPL = 0.195 –0.212 (0.204); PPH = 0.220 –0.262 (0.235); PW = 0.415 –0.470 (0.441); SBPA = 0.147 –0.177 (0.164); SPTI = 0.178 –0.213 (0.194); PEW = 0.173 –0.196 (0.184); PNW = 0.080 –0.103 (0.090); PPW = 0.245 –0.284 (0.262); HFL = 0.556 –0.624 (0.585); HFWmax = 0.148 –0.176 (0.163); HFWmin = 0.052 –0.066 (0.055); CS = 1.017 –1.111 (1.053); ES = 0.272 –0.304 (0.288); SI = 77–82 (79); OI = 27–28 (27); CI = 83–84 (84); WLI = 146–157 (152); SBI = 23–27 (25); PSI = 17–21 (19); PWI = 140–145 (143); PLI = 141–176 (156); NI = 127–169 (143); PNWI = 45–55 (49); NLI = 49–66 (59); FI = 265–332 (295).

Worker description: In full-face view, head subquadrate, longer than broad (CI 83–84). 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 short: when fully retracted, failing to reach the posterior margin of the head capsule by about two times the maximum width of the antennal scape (SI 77–82). 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 three 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 concave medially, rounding evenly into the lateral margins.

In profile view, compound eyes ovular and moderately large (OI 27–28), with 14 ommatidia in longest row. Pronotal declivity distinct: dorsal margin of anterior face of pronotum marked by a weak carina and change in sculpture; neck and anterior face of pronotum forming a ~120 ° angle. Mesosoma very weakly sinuate: promesonotum forming an even convexity from where it joins the pronotal declivity; propodeum weakly depressed below the level of the promesonotum and descending to the base of the propodeal spines on the posterior quarter. Promesonotal suture extending from the posterior margin of the procoxal insertion to the mesothoracic spiracle, which is 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 four spiracle diameters. Propodeal spines weakly developed and short (PSI 17–21), about half as long as the propodeal declivity, flared at the base, stout, triangular, and blunt. Propodeal declivity straight, forming a rounded ~150 ° angle with the base of the propodeal spines. Propodeal lobes rounded and weakly developed. Metapleural gland bulla small, extending from the metacoxal insertion a third of the way to the propodeal spiracle. Petiole moderately long (PLI 141–176), with tubercles anterodorsally. Subpetiolar process in the form of a blunt, triangular tooth which grades evenly into the ventral petiole margin posteriorly. Petiolar peduncle short: comprising about a quarter of the total petiole length. Petiolar node truncate dorsally; anterior face forming a ~100 ° angle with the dorsal face, which is flat; dorsal face meeting the posterior face at a ~120 ° angle; very short posterior face forms a ~120 ° angle with the caudal cylinder. Postpetiole evenly convex anterodorsally; weakly lobed ventrally.

In dorsal view, humeri developed: angulate anterolaterally and slightly wider than the rest of the mesosoma; mesothoracic spiracles 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 and 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 twice their length, the negative space between them “U” shaped. Petiolar peduncle with spiracles weakly protruding past the lateral margins. Petiolar node narrowed apically and flat dorsally, narrower than the peduncle and the caudal cylinder. Postpetiole narrow (PWI 140–145) and campaniform. Anterior margin of the postpetiole convex and rounds evenly into the lateral margins; lateral margins parallel to each other; posterior corners rounded; posterior margin flat. Metafemur moderately to strongly incrassate (FI 265–332).

Sculpture: median clypeal carina present, extending posteriorly to the frontal triangle, and flanked on either side by three weaker carinae. Lateral clypeal lobes with additional, weaker carinae; ground sculpture shining through weak areolae. Antennal scapes areolate. Cephalic dorsum areolate-rugulose, with costae over the ground sculpture, which become rugose on the posterior sixth of the head and between the frontal area and lateral margins of the head; concentric rugulae surrounding the antennal insertions. Lateral surfaces of head areolate-rugulose, with coarse rugae over the ground sculpture. Ventral surface of head smooth and shining medially, but otherwise weakly areolate with weak costulae. Pronotal neck areolate. Lateral surfaces of mesosoma weakly areolate, with coarse costae over the ground sculpture. Propodeal declivity areolate-strigulate. Dorsal surface of mesosoma with coarse rugae; propodeum with areolate ground sculpture. Femora finely, weakly areolate. Petiole uniformly areolate; a weak carina present laterally, extending longitudinally from the petiolar spiracle to the caudal cylinder; rugae on lateral faces of the node. Postpetiole uniformly areolate, with rugose sculpture on the dorsal and lateral surfaces. First gastral tergite shining through weak areolate sculpture; without spectral iridescence. First gastral sternite smooth and shining, without spectral iridescence.

Setae: antennal scapes and funiculi with short, subdecumbent 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 ~50, mesosoma ~26, petiole 8, postpetiole ~32, and first gastral tergite ~72 setae. Short, sparse pubescence present over the entire body, but difficult to detect against the densely sculptured integument.

Color: predominantly testaceous, with tibiae, tarsi, and sting testaceous yellow.

Male measurements & indices (n = 2): SL = 0.188 –0.241 (0.215); FRS = 0.128 –0.160 (0.144); CW = 0.559 –0.650 (0.605); CWb = 0.447 –0.571 (0.509); PoOC = 0.189 –0.241 (0.215); CL = 0.467 –0.576 (0.522); EL = 0.226 –0.268 (0.247); EW = 0.199 –0.211 (0.205); MD = 0.040 –0.041 (0.041); WL = 0.841 –0.974 (0.908); SPST = n/a; MPST = 0.237 –0.300 (0.269); PEL = 0.234 –0.288 (0.261); NOL = 0.143 –0.189 (0.166); NOH = 0.065 –0.099 (0.082); PEH = 0.183 –0.208 (0.196); PPL = 0.160 –0.205 (0.183); PPH = 0.201 –0.228 (0.215); PW = 0.492 –0.632 (0.562); SBPA = n/a; SPTI = n/a; PEW = 0.174 –0.202 (0.188); PNW = 0.164 –0.188 (0.176); PPW = 0.241 –0.280 (0.261); HFL = 0.611 –0.758 (0.685); HFWmax = 0.079 –0.101 (0.090); HFWmin = 0.033 –0.039 (0.036); CS = 0.681 –0.859 (0.770); ES = 0.326 –0.374 (0.350); SI = 42; OI = 43–48 (46); CI = 96–99 (97); WLI = 171–188 (179); SBI = n/a; PSI = n/a; PWI = 139; PLI = 140–146 (143); NI = 191–220 (205); PNWI = 93–94 (94); NLI = 61–66 (63); FI = 239–259 (249).

Male description: In full-face view, head subovate, about as broad as long (CI 96–99). Mandibles very weakly striate, shining, and armed with four teeth: the apical-most well developed, followed by three smaller preapical teeth. Anterior clypeal margin entire and weakly convex. Antennal scapes short: when fully retracted, failing to reach the posterior margin of the head capsule by about half the length of the antennal scape (SI 42). 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 times the maximum width of the antennal scape. Compound eyes strongly protruding past the lateral margins of the head capsule. margin of head convex behind the compound eyes; margins between the anterior margin of the compound eye and the mandibular insertions converging. Posterior head margin convex, rounding evenly into the lateral margins.

In profile view, compound eyes ovular and large (OI 43–48), 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 slightly beyond the posterior margin of the mesoscutellum. Propodeum strongly depressed, flat dorsally, and meeting the propodeal declivity at a broadly rounded ~90 ° angle. Propodeal spiracle moderately well developed, directed posterolaterally, and separated from the propodeal declivity by about three spiracle diameters. Propodeal spines absent. Propodeal lobes rounded and weakly developed. Metapleural gland bulla small, extending a quarter of the way between the insertion of the metacoxa and the propodeal spiracle. Petiole short (PLI 140–146), with 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 rounded; the convergence of the anterior and dorsal faces marked by a ~120 ° angle. Postpetiole flat anteriorly, meeting the dorsal face at ~120 ° angle; weakly concave ventrally.

In dorsal view, mesoscutum covering pronotum. Petiolar peduncle with spiracles strongly protruding past the lateral margins. Petiolar node about as wide as the peduncle, and wider than the caudal cylinder. Postpetiole narrow (PWI 139) and campaniform. Anterior margin of postpetiole convex, with the anterior corners evenly rounding into the lateral margins; lateral margins parallel to each other; posterior margin of postpetiole flat. Metafemur weakly to moderately incrassate (FI 239–259).

Sculpture: median clypeal lobe with multiple concentric carinae anteriorly. Antennal scapes weakly areolate. Dorsum of head weakly areolate, with weak, fine costulae between the frontal carinae. Lateral surface of head areolate, with weak, fine concentric costulae surrounding the compound eye. Ventral surface of head weakly areolate. Pronotal neck very weakly areolate. Anterior face of pronotum weakly areolate. Lateral surfaces of pronotum and mesopleurae predominantly smooth and shining, with weak, indistinct sculpture near the borders of the sclerites. Metapleuron and lateral face of propodeum areolate. Propodeal declivity weakly areolate, with weak, fine costulae. Dorsally, mesoscutum and mesoscutellum smooth and shining, with weak areolate sculpture along the Mayrian furrows. Propodeum weakly areolate. Femora weakly areolate. Petiole weakly areolate with coarse rugae 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 weakly, indistinctly sculptured, but mostly smooth and shining, without spectral iridescence. First gastral sternite smooth and shining, without spectral iridescence.

Setae: antennal scapes and funiculi with short, subdecumbent 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 testaceous, with antennae, legs, and genitalia light yellow. Head capsule slightly darker than the rest of the body.

Etymology: Geographical, from ‘Parral’, the type collection locality + ‘-ensis’ (= native to).

Comments: Temnothorax parralensis sp. nov., like its closest relatives T. rugosus and the annexus species group, appears to prefer nesting in hollow oak branches at mid elevations.

Figures

Figure 150 Geographical and elevational distribution of the rugosus group. (A) Temnothorax parralensis sp. nov. (B) T. rugosus. 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-150

Figure 151 Temnothorax parralensis sp. nov. (A–C) Holotype worker (LACMENT323355). (A) Full-face view. (B) Profile view. (C) Dorsal view. (D–F) Paratype male (LACMENT323356). (D) Full-face view. (E) Profile view. (F) Dorsal view. Scale bars 0.2 mm. Full-size DOI: 10.7717/peerj.11514/fig-151