Temnothorax augusti ( 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 : 122-128

Temnothorax augusti ( Baroni Urbani, 1978)

Distribution: Fig. 101A ; worker & gyne: Fig. 102 .

Leptothorax petiolatus Forel, 1901 a: 129 . Syntype workers. Cuernavaca , Mexico.

One worker here designated lectotype.

Macromischa petiolata (Forel) : Emery, 1924: 247. First combination in Macromischa (nec Macromischa petiolata Mayr, 1868: 15 (fossil species)).

Macromischa foreli Aguayo, 1931: 182 . Nomen novum for Macromischa petiolata (Forel) (nec Mayr).

Leptothorax augusti Baroni Urbani, 1978: 423 . Re-transfer to Leptothorax . Nomen novum for Leptothorax foreli (Aguayo) (nec Leptothorax foreli Santschi, 1907: 330 ).

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

Type material examined: Lectotype worker: MEXICO: Morelos: Cuernavaca, [collection date unknown], [collector unspecified, but Wheeler (1931) states that he made the collection], in Tillandsia , M.C.Z. cotype 21005 ( MCZENT00021005 , top specimen on pin) [ MCZC].

Paralectotype worker: same pin as lectotype (MCZENT00021005, bottom specimen on pin) [ MCZC] .

Non-type material examined: same data as previous, 1 dealate gyne (MCZENT00577105) [ MCZC].

Geographic range: Mid elevations in South-Central Mexico (Morelos) ( Fig. 101A ).

Worker diagnosis: The following character combination separates Temnothorax augusti from all other species in the salvini clade: moderately long antennal scapes, which surpass the posterior margin of the head by about the maximum width of the scape (SI 103–117); mesosoma about one and a half times as long as the width of the head (WLI 143–150); propodeal spines shorter than the length of the propodeal declivity (PSI 29); petiolar node subquadrate, and overhangs the caudal cylinder of the petiole; postpetiole narrow, less than two times the width of the petiole in dorsal view (PWI 187–190); first gastral tergite with very faint areolate sculpture; erect setae on the dorsal surface of the head; integument medium brown.

Similar species: Temnothorax acutispinosus sp. nov., T. subditivus , T. tenuisculptus , T. tuxtlanus sp. nov., species of the annexus , augusti , fuscatus , and salvini groups. Temnothorax augusti can be distinguished from the first three species by the shape of the dorsal margin of the mesosoma in profile, which is predominantly flat: in T. subditivus , the mesosoma is strongly arched, while T. tenuisculptus and T. tuxtlanus sp. nov. have a sinuate profile. Petiolar node shape is also a useful character for separating T. augusti from the above taxa: T. subditivus and the potentially co-occurring members of the salvini group have a squamiform petiolar node, which is much broader than the peduncle in dorsal view (only slightly wider in T. augusti ), and the nodes of the annexus group are erect and subquadrate, as opposed to leaning posteriorly in T. augusti ; T. tenuisculptus , like T. augusti , has a subquadrate petiolar node, but it does not lean posteriorly over the caudal cylinder; T. tuxtlanus sp. nov. and T. acutispinosus sp. nov. have rounded petiolar nodes in profile view. Temnothorax augusti can also be distinguished from T. tuxtlanus sp. nov. and T. acutispinosus sp nov. by the presence of erect setae on the dorsum of the propodeum. The potentially co-occurring members of the fuscatus group have a low, elongate petiolar node in profile view. Finally, T. augusti can be separated from fellow members of the augusti group by the combination of short propodeal spines, which are shorter than the length of the propodeal declivity (as long as or longer than the declivity in other augusti group members, except T. casanovai sp. nov.), and the shining, faintly areolate first gastral tergite (which is strongly areolate and dull in T. casanovai sp. nov.).

Worker measurements & indices (n = 2): SL = 0.605 –0.662 (0.634); FRS = 0.183 –0.190 (0.187); CW = 0.624 –0.630 (0.627); CWb = 0.566 –0.588 (0.577); PoOC = 0.278 –0.297 (0.288); CL = 0.693 –0.737 (0.715); EL = 0.156 –0.160 (0.158); EW = 0.118 –0.153 (0.136); MD = 0.162 –0.173 (0.168); WL = 0.812 –0.884 (0.848); SPST = 0.239 –0.252 (0.246); MPST = 0.247 –0.263 (0.255); PEL = 0.306 –0.340 (0.323); NOL = 0.177 –0.212 (0.195); NOH = 0.116 –0.124 (0.120); PEH = 0.208 –0.225 (0.217); PPL = 0.137 –0.153 (0.145); PPH = 0.186 –0.193 (0.190); PW = 0.383 –0.418 (0.401); SBPA = 0.144 –0.152 (0.148); SPTI = 0.161 –0.180 (0.171); PEW = 0.128 –0.129 (0.129); PNW = 0.172 –0.184 (0.178); PPW = 0.239 –0.245 (0.242); HFL = 0.681 –0.684 (0.683); HFWmax = 0.155 –0.161 (0.158); HFWmin = 0.046 –0.049 (0.048); CS = 0.913 –0.957 (0.935); ES = 0.215 –0.237 (0.226); SI = 103–117 (110); OI = 24–25 (24); CI = 80–82 (81); WLI = 143–150 (147); SBI = 25–26 (26); PSI = 29; PWI = 187–190 (188); PLI = 222–223 (223); NI = 153–171 (162); PNWI = 134–143 (139); NLI = 58–62 (60); FI = 329–337 (333).

Worker description: In full-face view, head subquadrate, longer than broad (CI 80–82). Mandibles densely, finely striate, weakly 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 weakly emarginated medially. Antennal scapes moderately long: when fully retracted, surpassing the posterior margin of the head capsule by about the maximum width of the scape (SI 103–117). Antennae 12-segmented; antennal club of composed of three 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 times the maximum width of the antennal scape. Compound eyes moderately protruding past the lateral margins of the head capsule. Lateral margin of head convex, forming a continuous arc from the mandibular insertions to the posterior margin of the head. Posterior head margin convex but rounding evenly into the lateral margins.

In profile view, compound eyes ovular and moderately large (OI 24–25), with 11 ommatidia in longest row. Pronotal declivity indistinct, but neck and anterior face of pronotum forming a ~120 ° angle. Mesosoma convex from where it joins the pronotal neck to the pronotal dorsum, then flat to the base of the propodeal spines. 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, continuing dorsally as a disruption in the sculpture. Propodeal spiracle poorly developed, directed posterolaterally, and separated from the propodeal declivity by about four and a half spiracle diameters. Propodeal spines moderately well developed, but short (PSI 29), slightly shorter than the propodeal declivity, tapering evenly from the base, straight, and acute. Propodeal declivity straight, forming a rounded ~120 ° 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 long (PLI 222–223), without tubercles anterodorsally. Subpetiolar process in the form of a very small, acute tooth; ventral margin of petiole weakly bulging medially. Petiolar peduncle long: comprising about two thirds of the petiole. Petiolar node robust and erect, nearly squamiform: transition between peduncle and node marked by a rounded angle of ~120 °, resulting in a concave anterior node face; anterior face forming a ~100 ° angle with the dorsal face, which is weakly convex; dorsal face rounding evenly into the short posterior face, which forms a ~85 ° angle with the caudal cylinder, overhanging it. Postpetiole evenly rounded anteriorly, flattened dorsally, and weakly lobed ventrally.

In dorsal view, humeri developed: evenly rounded and wider than the rest of the mesosoma; mesothoracic spiracles not protruding past the lateral margins of the mesosoma. 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, joined by a transverse welt, and diverging apically, their apices separated from each other by about their length, the negative space between them “U” shaped. Petiolar peduncle with spiracles protruding past the lateral margins, broadened where they arise. Petiolar node campaniform: flattened posteriorly. Petiolar node broader than the peduncle, and about one and a quarter times as wide as the caudal cylinder. Postpetiole narrow (PWI 187–190) and campaniform, articulating with most of the anterior margin of the gaster, leaving small, angulate margins on each side exposed. Anterior margin of the postpetiole convex and evenly rounds into the lateral margins, which diverge to the angulate posterior corners; posterior margin flat. Metafemur strongly incrassate (FI 329–337).

Sculpture: median clypeal carina present, extending posteriorly nearly to the frontal triangle, and flanked on either side by two slightly weaker carinae. Lateral clypeal lobes with additional, weaker carinae; ground sculpture weakly areolate. Antennal scapes areolate. Cephalic dorsum areolate; costulae flanking the frontal carinae, and weak concentric costulae surrounding the antennal insertions. Lateral surfaces of head areolate, and weak rugulose sculpture between the compound eye and the mandibular insertion. Ventral surface of head weakly areolate. Mesosoma areolate-rugulose, with weak rugulae overlying it dorsally. Femora weakly areolate. Petiole and postpetiole predominantly smooth and shining, with traces of weak areolate sculpture. Gaster smooth and shining, with traces of areolate sculpture and spectral iridescence on the basal half of the first gastral tergite.

Setae: antennal scapes and funiculi with short, decumbent 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 ~40, mesosoma ~26, petiole 6, postpetiole ~10, and first gastral tergite ~40 setae. Short, sparse pubescence present over the entire body, but difficult to detect against the ground sculpture.

Color: predominantly medium brown, with yellowish tarsi.

Gyne measurements & indices (n = 1): SL = 0.746; FRS = 0.288; CW = 0.874; CWb = 0.819; PoOC = 0.361; CL = 0.931; EL = 0.255; EW = 0.197; MD = 0.204; WL = 1.437; SPST = 0.323; MPST = 0.416; PEL = 0.483; NOL = 0.224; NOH = 0.216; PEH = 0.373; PPL = 0.279; PPH = 0.311; PW = 0.859; SBPA = 0.371; SPTI = 0.378; PEW = 0.213; PNW = 0.300; PPW = 0.432; HFL = 0.900; HFWmax = 0.191; HFWmin = 0.070; CS = 1.285; ES = 0.354; SI = 91; OI = 28; CI = 88; WLI = 175; SBI = 45; PSI = 22; PWI = 203; PLI = 173; NI = 104; PNWI = 141; NLI = 46; FI = 273.

Gyne description: In full-face view, head subquadrate, longer than broad (CI 88). Mandibles densely, finely striate but weakly 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 91). Antennae 12-segmented; antennal club composed of three segments, with the apical-most segment longer than the preceding two in combination. Frontal carinae 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 evenly convex, converging from below the compound eyes to the mandibular insertions. Posterior head margin convex, rounding evenly into the lateral margins.

In profile view, compound eyes ovular and large (OI 28), with 22 ommatidia in longest row. Mesoscutum rounded evenly anteriorly, covering the dorsal surface of the pronotum, and flat dorsally. Mesoscutellum at the same level as the mesoscutum. Posterior margin of metanotum extending slightly past the posterior margin of the mesoscutum. Propodeal spiracle poorly developed, directed posterolaterally, and separated from the propodeal declivity by about five spiracle diameters. Propodeal spines stout and well developed, but short (PSI 22), about half as long as the propodeal declivity, tapering evenly from the base, directed posteriorly, straight, and blunt. Propodeal declivity straight and flat, forming a rounded ~100 ° angle with the base of the propodeal spines. Propodeal lobes rounded and very weakly developed. Metapleural gland bulla small, extending from the metacoxal insertion a third of the way to the propodeal spiracle. Petiole moderately long (PLI 173), without tubercles anterodorsally. Subpetiolar process in the form of a very small, acute tooth; ventral margin of the petiole bulging slightly medially. Petiolar peduncle long: comprising about two thirds of the petiole. Petiolar node robust and erect, nearly squamiform: transition between peduncle and node marked by a rounded angle of ~120 °, resulting in a concave anterior node face; anterior face forming a ~100 ° angle with the dorsal face, which is weakly convex; dorsal face rounding evenly into the short posterior face, which forms a ~85 ° angle with the caudal cylinder, overhanging it. Postpetiole subquadrate: flat anteriorly, transitioning into the flattened dorsal face through a rounded angle; ventral surface weakly lobed.

In dorsal view, mesoscutum covering pronotum anteriorly, but humeri visible laterally as slightly angulate sclerites. Propodeal spines broadly approximated basally and diverging apically, their apices separated from each other by about twice their length. Petiolar peduncle with spiracles protruding past the lateral margins, the peduncle constricted anterior to them. Petiolar node subovate and transversely broad. Petiolar node broader than the peduncle, and about one and a half times as wide as the caudal cylinder. Postpetiole moderately broad (PWI 203), anteroposteriorly compressed, and subquadrate, articulating with most of the anterior margin of the gaster, leaving small, angulate margins on each side exposed. Anterior margin of postpetiole flat, with corners marked by rounded angles as it transitions to the lateral margins, which weakly diverge to the angulate posterior corners; posterior margin flat. Metafemur moderately incrassate (FI 273).

Sculpture: median clypeal carina present but flanked by numerous equally strong carinae. Lateral clypeal lobes with additional weaker carinae; ground sculpture weakly areolate. Antennal scapes areolate. Cephalic dorsum costulate, with areolate-rugulose ground sculpture; weak concentric costulae surrounding the antennal insertions. Lateral surfaces of head sculptured similarly to the dorsum. Ventral surface of head sculptured similarly to the rest of the head, but weaker. Pronotal neck areolate. Pronotum, metapleuron and lateral face of the propodeum sculptured similarly to the head dorsum. Anepisternum and katepisternum weakly areolate on their anterior quarters, transitioning into stronger areolate sculpture posteriorly. Propodeal declivity weakly areolate. Mesoscutum and mesoscutellum with longitudinal striae over areolate ground sculpture. Femora areolate. Petiole and postpetiole weakly areolate. First gastral tergite weakly areolate, with weak spectral iridescence. Surface of the first gastral sternite with weak spectral iridescence.

Setae: antennal scapes and funiculi with short, decumbent 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 ground sculpture.

Color: predominantly medium brown, with yellowish tarsi.

Male: Unknown.

Etymology: Patronym, for the Swiss myrmecologist Auguste Forel, who originally described this species.

Comments: Temnothorax augusti is known only from the type series, which was collected from Tillandsia epiphytes near Cuernavaca, Morelos, Mexico by William Morton Wheeler. The epiphyte in which the nest series was collected was shared with two other ant species: Crematogaster crinosa Mayr , a common inhabitant of the canopy and disturbed areas in the Neotropics, and Cephalotes wheeleri (Forel) , a much less common arboreal species known only from Central Mexico ( Wheeler, 1910). The morphologically closest species to T. augusti is T. casanovai sp. nov., which was collected in neighboring Puebla state, Mexico from the limb of a pitahaya cactus, Hylocereus undatus , a hemiepiphytic species commonly cultivated for its fruit. Based on multiple morphological disparities between the two, including gross size, distance between the base of the propodeal spines, degree of sculpture on the first gastral tergite, and color, I choose to keep these species separate in the current revision. This issue should be revisited as more collections become available. This species is reported from Quintana Roo by Lachaud & Lachaud (2013); I have not personally examined these specimens, so I have excluded it from the range for the moment.

Figures

Figure 101 Geographical and elevational distribution of the augusti group. (A) Temnothorax augusti (B) T. aureus sp. nov. (C) T. leucacanthoides sp. nov. (D) T. leucacanthus. 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-101

Figure 102 Temnothorax augusti. (A–C) Lectotype worker (MCZENT00021005). (A) Full-face view. (B) Profile view. (C) Dorsal view. (D-F) Gyne (MCZENT00577105). (D) Full-face view. (E) Profile view. (F) Dorsal view. Scale bars 0.2 mm. Full-size DOI: 10.7717/peerj.11514/fig-102