Temnothorax tenuisculptus ( 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 : 441-446

Temnothorax tenuisculptus ( Baroni Urbani, 1978)

Distribution, worker & gyne: Fig. 169 .

Leptothorax tenuisculptus Baroni Urbani, 1978: 517 . Holotype worker. Pueblo Nuevo , Veracruz, Mexico.

Temnothorax tenuisculptus (Baroni Urbani) : Bolton, 2003: 272. First combination in Temnothorax .

Type material examined: Holotype worker: MEXICO: Veracruz: Pueblo Nuevo , near Tetzonapa, E.O. Wilson 9 August 1953, rainforest, 1 worker (M.C.Z. Type 32435, MCZENT00032435 , top specimen on pin) [ MCZC].

Paratype workers: same pin as holotype, 1 worker (bottom specimen on pin) [ MCZC]; same data as holotype, 1 worker (M.C.Z. Type 32435, MCZENT00578578) [ MCZC] 1 worker (images of CASENT0913005 examined on antweb.org) [ NHMB] .

Non-type material examined: MEXICO: San Luis Potosí: [quarantine], 13 April 1976, J. Kline & R. Eads # ANTC43726 , Quercus sp. with Epidendrum sp. orchid plant, 7 alate gynes & 3 workers ( CASENT0756076 - CASENT0756084 ) [ USNM]. Veracruz: 9 km NE San Andrés Tuxtla, 18.51232 ° N 95.16729 ° W ± 4 m, 970 m ± 5 m 4 June 2016, M.M. Prebus #MMP02671, mixed tropical temperate mesic forest, between leaves and stalk of Tillandsia , 4 workers ( CASENT0757196 - CASENT0757198 , CASENT0758683 ) [ UCDC].

Geographic range: Low elevations of southern Mexico (Veracruz) ( Fig. 169H ).

Worker diagnosis: Temnothorax tenuisculptus can be separated from all other species in the salvini clade by the following character combination: in profile view, dorsum of mesosoma strongly sinuate; propodeum depressed below the level of the promesonotum; hind femora strongly incrassate; petiolar node subquadrate, not leaning posteriorly; postpetiole moderately broad, greater than 1.5 times the width of the caudal cylinder of the petiole, but less than 2.2 times; setae on head, mesosoma, waist segments and gaster erect, moderately long, sparse and blunt (never long and tapering);integument predominantly testaceous brown, with apex of mandibles, pedicel of antenna, pronotal neck, tibiae, tarsi, and sting testaceous yellow.

Similar species: Temnothorax acutispinosus sp. nov., T. tuxtlanus sp. nov., T. xincai sp. nov., members of the augusti and subditivus groups. Temnothorax tenuisculptus can be separated from all of the above species, except for the augusti and subditivus groups by the strongly incrassate hind femora. The petiolar node, which is erect in T. tenuisculptus , can be used to distinguish it from similar appearing members of the augusti group, which have posteriorly leaning petiolar nodes. Due to the smooth integument of the head, T. tenuisculptus may be confused with T. politus , but the short, blunt tipped setae and sinuate mesosoma of the former will separate it from T. politus , which has long, tapering setae and an arched mesosoma. Similarly, T. tenuisculptus may be mistaken for some of the more lightly sculptured specimens of T. subditivus but differs from it by the sinuate mesosoma (uniformly convex in T. subditivus ) and the subquadrate petiolar node (squamiform in T. subditivus ).

Worker measurements & indices (n = 9): SL = 0.501 –0.592 (0.554); FRS = 0.171 –0.205 (0.191); CW = 0.575 –0.698 (0.654); CWb = 0.516 –0.643 (0.604); PoOC = 0.255 –0.312 (0.283); CL = 0.647 –0.767 (0.720); EL = 0.134 –0.169 (0.154); EW = 0.096 –0.127 (0.114); MD = 0.158 –0.189 (0.170); WL = 0.748 –0.919 (0.857); SPST = 0.216 –0.317 (0.267); MPST = 0.244 –0.320 (0.279); PEL = 0.300 –0.388 (0.353); NOL = 0.147 –0.199 (0.176); NOH = 0.119 –0.159 (0.139); PEH = 0.196 –0.255 (0.222); PPL = 0.156 –0.215 (0.178); PW = 0.372 –0.456 (0.420); SBPA = 0.133 –0.194 (0.166); SPTI = 0.205 –0.274 (0.250); PEW = 0.131 –0.164 (0.153); PNW = 0.136 –0.202 (0.170); PPW = 0.234 –0.288 (0.266); HFL = 0.535 –0.668 (0.621); HFWmax = 0.151 –0.199 (0.180); HFWmin = 0.042 –0.056 (0.050); CS = 0.840 –1.023 (0.964); ES = 0.182 –0.230 (0.211); SI = 89–97 (92); OI = 21–23 (22); CI = 80–86 (84); WLI = 138–145 (142); SBI = 23–30 (27); PSI = 27–34 (31); PWI = 167–180 (174); PLI = 174–233 (199); NI = 111–147 (128); PNWI = 94–126 (111); NLI = 40–57 (50); FI = 348–392 (361).

Worker description: In full-face view, head subquadrate, longer than broad (CI 80–86). Mandibles densely 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 evenly convex medially. Antennal scapes moderately long: when fully retracted, failing to reach the posterior margin of the head capsule by about the width of the scape (SI 89–97). 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 twice the maximum width of the antennal scape. Compound eyes weakly 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 flat but rounding evenly into the lateral margins.

In profile view, compound eyes ovular and moderately large (OI 21–23), with 10 ommatidia in longest row. Pronotal declivity indistinct, neck and anterior face of pronotum forming a ~120 ° angle. Mesosoma evenly convex from where it joins the pronotal neck to the propodeum. Promesonotal suture extending from the posterior margin of the procoxal insertion to the mesothoracic spiracle, which is moderately well developed, then continuing dorsally as a disruption in the ground sculpture. Metanotal groove visible as a weak sulcus and 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 three and a half spiracle diameters. Propodeal spines well developed and very long (PSI 27–34), slightly longer than the propodeal declivity, flared at the base, straight, and acute. Propodeal declivity weakly concave, forming a rounded ~120 ° angle with the base of the propodeal spines. Propodeal lobes rounded and weakly developed. Metapleural gland bulla large, extending from the metacoxal insertion three quarters of the way to the propodeal spiracle. Petiole moderately long (PLI 174–233), without tubercles anterodorsally. Subpetiolar process in the form of a small, acute, spiniform tooth; ventral margin of petiole flat posterior to it. Petiolar peduncle moderately long: comprising a little more than a third of the total petiole length. Petiolar node robust, erect, and subquadrate: transition between peduncle and node marked by a rounded angle of ~110 °; anterior face forming a ~100 ° angle with the dorsal face, which is weakly convex; dorsal face meeting the posterior face at a rounded ~90 ° angle; posterior face forms a ~90 ° angle with the caudal cylinder. Postpetiole evenly rounded anterodorsally; weakly lobed ventrally.

In dorsal view, humeri developed and distinct: evenly rounded and slightly 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 visible as 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 narrowly approximated basally and diverging apically, their apices separated from each other by slightly less than their length, the negative space between them “V” shaped. Petiolar peduncle with spiracles slightly protruding past the lateral margins, and slightly constricted anterior to them. Petiolar node ovular, slightly narrower anteriorly and flattened posteriorly; node the same width as the peduncle, and evenly grading into the caudal cylinder, which is about the same width as the node. Postpetiole narrow (PWI 167–180) and subquadrate. Anterior margin of the postpetiole weakly convex, meeting the lateral margins at a rounded ~90 ° angle; lateral margins parallel to each other; lateral margin meeting the posterior margin at a ~90 ° angle; posterior margin flat. Metafemur strongly incrassate (FI 348–392).

Sculpture: median clypeal carina present, extending posteriorly to the level of the antennal insertions, and flanked on either side by one slightly weaker carina. Lateral clypeal lobes with additional, weaker carinae; ground sculpture smooth and shining. Antennal scapes finely areolate-costulate. Cephalic dorsum weakly sculptured: finely costulate between the frontal carinae; fine concentric costulae surrounding the antennal insertions; weak areolate sculpture on the dorsolateral margins behind the compound eyes and on the posterior quarter of the head, otherwise shining. Lateral surfaces of head weakly areolate, with fine concentric costulae around the compound eyes, and fine rugulose sculpture between the compound eye and mandibular insertion. Ventral surface of head smooth and shining medially, with weak costulae and areolae laterally. Pronotal neck areolate. Lateral face of the pronotum areolate; the remainder of the lateral surface of the mesosoma finely rugulose. Propodeal declivity weakly areolate. Dorsal surface of mesosoma finely areolate, with rugulae overlying the ground sculpture; rugulose sculpture much weaker on the propodeum. Femora shining through weak areolate sculpture. Petiole predominantly weakly areolate, but smooth and shining on the ventral surface of the peduncle. Postpetiole weakly areolate, with sculpture becoming stronger on the posterior quarter and the lateral faces. First gastral tergite and sternite smooth and shining, with weak spectral iridescence.

Setae: antennal scapes and funiculi with short, adpressed pilosity. Dorsum of the head, pronotum, waist segments, and gaster with moderately abundant, erect, stout, blunt-tipped setae, the longest of which are about the width of the compound eye. The head bears ~30, mesosoma ~22, petiole 6, postpetiole ~8, and first gastral tergite ~18 setae. Short, sparse, adpressed pubescence present over the entire body, but difficult to detect against the densely sculptured integument.

Color: predominantly testaceous brown, with apex of mandibles, pedicel of antenna, pronotal neck, tibiae, tarsi, and sting testaceous yellow.

Gyne measurements & indices (n = 2): SL = 0.625 –0.634 (0.630); FRS = 0.236 –0.249 (0.243); CW = 0.815 –0.834 (0.825); CWb = 0.756 –0.757 (0.757); PoOC = 0.328 –0.333 (0.331); CL = 0.826 –0.829 (0.828); EL = 0.230 –0.247 (0.239); EW = 0.187 –0.204 (0.196); MD = 0.155 –0.171 (0.163); WL = 1.321 –1.322 (1.322); SPST = 0.340 –0.344 (0.342); MPST = 0.344 –0.351 (0.348); PEL = 0.478 –0.483 (0.481); NOL = 0.216 –0.219 (0.218); NOH = 0.173 –0.193 (0.183); PEH = 0.317 –0.325 (0.321); PPL = 0.229 –0.235 (0.232); PW = 0.832 –0.833 (0.833); SBPA = 0.361 –0.370 (0.366); SPTI = 0.366 –0.376 (0.371); PEW = 0.214 –0.224 (0.219); PNW = 0.216; PPW = 0.392 –0.408 (0.400); HFL = 0.774 –0.798 (0.786); HFWmax = 0.171 –0.193 (0.182); HFWmin = 0.058 –0.076 (0.067); CS = 1.170 –1.171 (1.170); ES = 0.324 –0.349 (0.336); SI = 83–84 (83); OI = 28–30 (29); CI = 91–92 (91); WLI = 175; SBI = 48–49 (48); PSI = 26; PWI = 182–183 (183); PLI = 203–211 (207); NI = 113–125 (119); PNWI = 96–101 (99); NLI = 45–45 (45); FI = 254–295 (274).

Gyne description: In full-face view, head subquadrate, slightly longer than broad (CI 91–92). 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 weakly emarginated medially. Antennal scapes moderately long: when fully retracted, just reaching the posterior margin of the head capsule (SI 83–84). 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 and a half times the maximum width of the antennal scape. Compound eyes moderately 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 compound eyes and the mandibular insertions. Posterior head margin flat, rounding evenly into the lateral margins.

In profile view, compound eyes ovular and large (OI 28–30), with 16 ommatidia in longest row. Mesoscutum rounded evenly anteriorly, covering the dorsal surface of the pronotum, and weakly convex dorsally, nearly flat. Mesoscutellum very slightly depressed below the level of the mesoscutum and gently sloping posteriorly. 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 stout and well developed, but short (PSI 26), about as two thirds as long as the propodeal declivity, tapering evenly from the base, directed posterodorsally, straight, and acute. Propodeal declivity straight and flat, forming a rounded ~120 ° angle with the base of the propodeal spines. Propodeal lobes rounded and very weakly developed. Metapleural gland bulla large, extending from the metacoxal insertion three quarters of the way to the propodeal spiracle. Petiole long (PLI 203–211), without tubercles anterodorsally. Subpetiolar process in the form of a small, triangular tooth, which grades evenly into the ventral margin of the petiole posteriorly. Petiolar peduncle moderately long: comprising a little more than a third of the total petiole length. Petiolar node robust and erect: transition between peduncle and node an evenly rounded ~130 ° angle, resulting in a very slightly concave anterior node face; anterior face forming a rounded ~100 ° angle with the dorsal face, which is flat; dorsal face meeting the posterior face at a ~100 ° angle; posterior face forms a ~90 ° angle with the caudal cylinder. Postpetiole evenly rounded anterodorsally, bulging slightly 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 one and a half times their length. Petiolar peduncle with spiracles not protruding past the lateral margins, but slightly narrowed anterior to them. Petiolar node subquadrate, slightly broadened transversely. Petiolar node slightly narrower than the peduncle, and evenly grading into the caudal cylinder, which is about the same width as the node. Postpetiole narrow (PWI 182–183), anteroposteriorly compressed, and subquadrate. Anterior margin of postpetiole flat, with corners marked by rounded angles as it transitions to the lateral margins; lateral margins parallel to each other; posterior corners angulate; posterior margin broadly flat. Metafemur moderately incrassate (FI 254–295).

Sculpture: median clypeal carina present, extending from the anterior margin nearly to frontal triangle, and flanked by 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 that becomes costate between the frontal carinae; concentric costulae surround the antennal insertions. Lateral surfaces of head areolate, with rugose sculpture overlying the ground sculpture. Ventral surface of head smooth and shining medially, with weak areolate-rugulose sculpture laterally and posteriorly. Pronotal neck areolate. Anterior face of pronotum shining and weakly, indistinctly sculptured. Lateral face of pronotum costate. Anepisternum and katepisternum shining on their anterior halves, transitioning into weak areolate-costulate sculpture posteriorly. Metapleuron areolate, with costulae. Propodeum weakly areolate laterally. Propodeal declivity weakly areolate. Mesoscutum with costulae over areolate ground sculpture; a patch of finely areolate sculpture present anteromedially. Mesoscutellum longitudinally areolate-costulate. Metanotum areolate. Propodeum areolate, with weak rugae. Femora shining, with traces of weak areolate sculpture. Petiole uniformly finely areolate, with parallel rugae that are dorsoventrally oriented around the petiolar node; dorsum of node rugose. Postpetiole shining through weak areolate sculpture anteriorly, areolate laterally and dorsally; fine concentric costulae dorsally. First gastral tergite and sternite smooth and shining, with weak spectral iridescence.

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

Color; predominantly testaceous brown, with apex of mandibles, pedicel of antenna, pronotal neck, tibiae, tarsi, and sting testaceous yellow.

Male: Unknown.

Etymology: Morphological, from the Latin ‘tenuis’ (= weak) + ‘sculptus’ (= sculptured), probably in reference to the smooth and shining integument of the head.

Comments: This species is only known from a few collections, including lowland rainforest in Veracruz, Mexico; a nest from between the leaves of Tillandsia in mid-elevation mesic forest in Veracruz, and a nest in an oak branch bearing Epidendrum orchids, which was intercepted in a shipment from Mexico at the U.S. border by customs officials. This is an arboreally nesting species, similar to the species of the annexus species group, with which it is closely related. Very little morphological variation can be seen between the three collections of this species that I have observed.

Figures

Figure 169 Temnothorax tenuisculptus. (A–C) Holotype worker (MCZENT00032435). (A) Full-face view. (B) Profile view. (C) Dorsal view. (D–G) Gyne (CASENT0756078). (D) Full-face view. (E) Profile view. (F) Dorsal view. (G) Wings. (H) Geographical and elevational distribution of specimens examined. Type locality is represented by a triangle, non-type localities are represented by circles. Bounding box in inset map shows location of main map. Scale bars 0.2 mm. Full-size DOI: 10.7717/peerj.11514/fig-169