Temnothorax ixili ( 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 : 188-193

Temnothorax ixili ( Baroni Urbani, 1978)

Distribution: Fig. 114C ; worker & gyne: Fig. 118 .

Leptothorax ixili Baroni Urbani, 1978: 459 , figs. 67, 111. Holotype worker. Guatemala.

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

Type material examined: Holotype worker: GUATEMALA: [intercepted in quarantine: San Francisco, California, U.S.A.] 30 April 1946, SF 20968, 46-5352, Oncidium sp. , pin includes teneral gyne which is missing a head ( USNMENT00529550 ) [ USNM].

Paratype workers: same data as holotype, 3 workers (CASENT0758364) [ USNM] 3 workers (LACMENT323191) [ LACM]; [intercepted in quarantine] 6 May 1938, EQR4815, Oncidium sp. , 3 workers (bearing a label reading “ PARATYPUS ”, but unreported in Baroni Urbani, 1978, MCZ-ENT00581829) [ MCZC] 1 worker (images of CASENT0912951 examined on antweb.org) [ NHMB] .

Non-type material examined: GUATEMALA: Zacapa: 7.5 km NE Teculután , 15.04367 ° N 89.67501 ° W ± 30 m, 475 m, 28 June 2009, J. Longino #JTL6795-s, stream gully in dry scrub, ex sifted leaf litter, 1 worker (CASENT0611673) [ JTLC] 1 worker (CASENT0611669) [ JTLC] 1 worker (CASENT0611665) [ JTLC] ; 16 km NE Teculután , 14.86383 ° N 89.78801 ° W ± 57 m, 600 m, 24 June 2009, C. Beza #MGB1338, tropical thorn scrub, ex sifted leaf litter, 1 dealate gyne (CASENT0611679) [ JTLC] 1 worker (CASENT0611678) [ JTLC] 1 worker (CASENT0732589) [ JTLC] .

Geographic range: Low elevations of Guatemala (Zacapa) ( Fig. 114C ).

Worker diagnosis: Temnothorax ixili can be separated from all other species in the salvini clade by the following character combination: antennal scapes moderately long, just reaching the posterior margin of the head capsule (SI 83–92); compound eyes small (OI 24–25); head sculpture areolate, with areolae arranged into columns by weak longitudinal striae; body moderately compact (WLI 137–148); metanotal groove absent; propodeum not strongly depressed; propodeal spines shorter than the propodeal declivity and dentate (PSI 22–26); propodeal spines broadly approximated in dorsal view (SBI 30–34); hind femora weakly to moderately incrassate (FI 245–300); petiolar node erect and dorsally rounded, not overhanging the caudal cylinder in profile view; petiolar node compact, not elongate (NI 137–160); petiolar node slightly broader than caudal cylinder in dorsal view (PNWI> 115); dorsum of postpetiole sculptured; antennal scapes with short, decumbent pilosity; setae on head, mesosoma, waist segments and gaster erect, short, sparse and blunt (never long and tapering); integument predominantly dark brown, with trochanters, meso- and metacoxae, tibiae, tarsi, and sting very light yellow.

Similar species: Temnothorax acuminatus sp. nov., T. acutispinosus sp. nov., T. subditivus , T. tuxtlanus sp. nov., species of the augusti , goniops , and pulchellus groups, species of the sallei clade. Temnothorax ixili can be distinguished from similar appearing members of the sallei clade (e.g., T. manni , T. mexicanus , T. punctithorax ) by the petiole, which lacks a transverse carina anterodorsally. Unlike the long, dorsally directed propodeal spines of T. acutispinosus sp. nov., T. ixili has short propodeal teeth that are directed posterodorsally. Temnothorax ixili has a moderately broad postpetiole in dorsal view, whereas T. tuxtlanus sp. nov. has a relatively narrow postpetiole (PWI <150). Temnothorax altinodus sp. nov. has comparatively strongly incrassate hind femora (FI 327). Temnothorax ixili can be separated from T. subditivus and the augusti group by the structure of the petiolar node, which is erect, dorsally rounded, and only slightly broader than the caudal cylinder in dorsal view, as opposed to squamiform in T. subditivus , or leaning posteriorly over the caudal cylinder in the augusti group. Temnothorax ixili can be distinguished from the pulchellus group by the combination of a relatively longer mesosoma (WLI> 135 vs. <135 in most pulchellus group members) and the relatively broad petiolar node in dorsal view (PNWI> 115 vs. <115 in most pulchellus group members). Temnothorax hippolytus sp. nov. from Cuba and T. albispinus from Puerto Rico may approach these dimensions, but they can be separated from T. ixili by their very broad postpetioles (PWI> 240), among other features. Temnothorax ixili can be distinguished from other goniops group members by the short, dentate propodeal spines (longer than the propodeal declivity and spiniform in T. goniops and T. huehuetenangoi ), the sculptured head and postpetiole (smooth and shining in T. xincai sp. nov.), and the relatively broad, areolate petiolar node (narrower, on average, in T. achii sp. nov., and with overlying rugae).

Worker measurements & indices (n = 9): SL = 0.407 –0.451 (0.427); FRS = 0.152 –0.172 (0.163); CW = 0.491 –0.551 (0.524); CWb = 0.459 –0.514 (0.485); PoOC = 0.215 –0.251 (0.234); CL = 0.559 –0.607 (0.583); EL = 0.130 –0.143 (0.136); EW = 0.096 –0.112 (0.104); MD = 0.100 –0.130 (0.119); WL = 0.654 –0.742 (0.693); SPST = 0.157 –0.187 (0.170); MPST = 0.209 –0.235 (0.221); PEL = 0.262 –0.309 (0.288); NOL = 0.149 –0.185 (0.167); NOH = 0.101 –0.124 (0.113); PEH = 0.137 –0.218 (0.189); PPL = 0.157 –0.199 (0.176); PPH = 0.168 –0.277 (0.204); PW = 0.325 –0.365 (0.345); SBPA = 0.139 –0.169 (0.154); SPTI = 0.171 –0.226 (0.202); PEW = 0.117 –0.151 (0.137); PNW = 0.149 –0.194 (0.175); PPW = 0.254 –0.324 (0.294); HFL = 0.421 –0.480 (0.454); HFWmax = 0.115 –0.138 (0.123); HFWmin = 0.040 –0.049 (0.044); CS = 0.742 –0.818 (0.776); ES = 0.178 –0.197 (0.188); SI = 83–92 (88); OI = 24–25 (24); CI = 80–85 (83); WLI = 137–148 (143); SBI = 30–34 (32); PSI = 22–26 (25); PWI = 197–233 (214); PLI = 143–180 (164); NI = 137–160 (148); PNWI = 118–138 (128); NLI = 55–64 (58); FI = 245–300 (279).

Worker description: In full-face view, head subquadrate, longer than broad (CI 80–85). 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 evenly convex medially. Antennal scapes short: when fully retracted, just reaching the posterior margin of the head capsule (SI 83–92). Antennae 12-segmented; antennal club of composed of three segments, with the apical-most segment slightly 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 weakly convex, nearly flat, forming a continuous low 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, longitudinally elongate, and moderately large (OI 24–25), with 10 ommatidia in longest row. Pronotal declivity indistinct, but neck and anterior face of pronotum forming a ~120 ° angle. Mesosoma very weakly from where it joins the pronotal neck to the propodeal spines; propodeum slightly flatter, giving the dorsum of the mesosoma a weakly sinuate profile. 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 moderately well developed, directed posterolaterally, and separated from the propodeal declivity by about three spiracle diameters. Propodeal spines poorly developed and short (PSI 22–26), half the length of the propodeal declivity, triangular, flared at the base, slightly upturned, and acute. Propodeal declivity with weak carinae extending between the base of the propodeal spines and the propodeal lobes; declivity straight, 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 slightly less than halfway to the propodeal spiracle. Petiole moderately long (PLI 143-180), without tubercles anterodorsally. Subpetiolar process in the form of a small, triangular, blunt tooth; ventral margin of petiole flat posterior to it. Petiolar peduncle short: comprising about a third of the petiole length. Petiolar node robust and subquadrate: transition between peduncle and node marked by a rounded angle of ~120 °, resulting in a concave anterior node face; anterior face forming a ~90 ° angle with the dorsal face, which is convex; dorsal face rounding evenly into the short posterior face, which forms a ~100 ° angle with the caudal cylinder. Postpetiole evenly rounded anteriorly, convex dorsally, and weakly lobed ventrally.

In dorsal view, humeri poorly developed: evenly rounded and only slightly 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 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 very weakly protruding past the lateral margins, not noticeably constricted anterior to them. Petiolar node campaniform: evenly convex anteriorly, flattened posteriorly; node wider than the peduncle, and about one and quarter times as wide as the caudal cylinder. Postpetiole moderately to very broad (PWI 197–233) 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 flat and evenly rounds into the lateral margins, which are parallel to the angulate posterior corners; posterior margin flat. Metafemur moderately incrassate (FI 245–300).

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 weakly areolate. Cephalic dorsum evenly areolate and arranged into longitudinal columns by costulae between the frontal carinae. Lateral surfaces of head uniformly areolate, with dense rugulose sculpture between the compound eye and the mandibular insertion. Ventral surface of head smooth and shining anteriorly, weakly areolate posteriorly. Mesosoma and waist segments uniformly areolate, with areolae arranged into longitudinal rows by costulae on the lateral face of the pronotum, and very fine costulae on the dorsal face of the pronotum; propodeal declivity weakly areolate. Femora shining through traces of shallow areolate sculpture. First gastral tergite smooth and shining, with weak spectral iridescence. First gastral sternite smooth and shining.

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 ~24, mesosoma ~20, petiole 6, postpetiole ~12, and first gastral tergite ~38 setae. Longer, flexuous setae on the gular region, and the ventrites of the gaster. Short, sparse pubescence present over the entire body, but difficult to detect against the densely sculptured integument.

Color: predominantly medium brown, with mandibles and antennae testaceous yellow. Trochanters, Meso- and metacoxae, tibiae, tarsi, and sting very light yellow, nearly white.

Gyne measurements & indices (n = 1): SL = 0.434; FRS = 0.192; CW = 0.585; CWb = 0.560; PoOC = 0.245; CL = 0.628; EL = 0.183; EW = 0.142; MD = 0.109; WL = 1.035; SPST = 0.202; MPST = 0.268; PEL = 0.352; NOL = 0.201; NOH = 0.121; PEH = 0.238; PPL = 0.196; PPH = 0.253; PW = 0.622; SBPA = 0.273; SPTI = 0.257; PEW = 0.172; PNW = 0.228; PPW = 0.376; HFL = 0.527; HFWmax = 0.118; HFWmin = 0.047; CS = 0.874; ES = 0.254; SI = 78; OI = 29; CI = 89; WLI = 185; SBI = 49; PSI = 20; PWI = 219; PLI = 180; NI = 166; PNWI = 133; NLI = 57; FI = 251.

Gyne description: In full-face view, head subquadrate, about as long as broad (CI 89). Antennal scapes short: when fully retracted, failing to reach the posterior margin of the head capsule by about the maximum width of the scape (SI 78). Antennae 12-segmented; antennal club composed of three segments, with the apical-most segment as long as the preceding two in combination. 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 evenly convex medially. 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 evenly convex, converging from below the compound eyes to the mandibular insertions. Posterior head margin flat, rounding evenly into the lateral margins.

In profile view, compound eyes ovular and large (OI 29), with 14 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 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 teeth stout, poorly developed, and short (PSI 20), about a third as long as the propodeal declivity, triangular, directed posteriorly, straight, and blunt. Propodeal declivity with carinae that extend from the base of the propodeal spine to the propodeal lobes; declivity straight and flat, forming a ~90 ° angle with the base of the propodeal spines. Propodeal lobes rounded and very weakly developed. Metapleural gland bulla small, extending from the metacoxal insertion halfway to the propodeal spiracle. Petiole moderately long (PLI 180), without tubercles anterodorsally. Subpetiolar process in the form of a small, triangular, blunt tooth, which grades evenly into the ventral margin of the petiole posteriorly; ventral margin of petiole flat. Petiolar peduncle moderately long: comprising slightly less than half the length of the petiole. Petiolar node erect: transition between peduncle and node evenly rounded, resulting in a very slightly concave anterior node face; anterior face forming a rounded ~90 ° angle with the dorsal face, which is short and evenly convex; dorsal face rounding evenly into the short posterior face, which forms a ~100 ° angle with the caudal cylinder. Postpetiole evenly rounded anterodorsally, bulging slightly before it transitions into the flattened dorsal face; ventral surface weakly lobed.

In dorsal view, mesoscutum covering pronotum anteriorly, but humeri visible laterally as slightly angulate sclerites. Propodeal spines weakly diverging apically, their apices separated from each other by about three and a half times their length. Petiolar peduncle with spiracles not protruding past the lateral margins. Petiolar node trapezoidal: widest anteriorly, lateral faces converge to the slightly narrower posterior face. Petiolar node wider than the peduncle, and about one and a half times as wide as the caudal cylinder. Postpetiole moderately broad (PWI 219) and campaniform, 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 251).

Sculpture: median clypeal carina present, but indistinct against the densely areolate-costulate ground sculpture. Lateral clypeal lobes with additional weaker carinae. Antennal scapes weakly areolate. Cephalic dorsum densely areolate-costate. Lateral surfaces of head with sculptured similarly to the cephalic dorsum, but with rugose sculpture between the compound eye and mandibular insertion. Ventral surface of head weakly areolate-costulate. Pronotal neck areolate. Mesosoma longitudinally areolatecostulate, but sculpture weakening on the anepisternum and katepisternum. Propodeal declivity weakly areolate. Mesoscutum areolate-costulate, with small patches of weaker sculpture anteromedially, and surrounding the wing bases. Mesoscutellum smooth and shining medially, surrounded by weak areolate-costulate sculpture. Femora shining, with traces of weak areolate sculpture that become stronger distally. Petiole and postpetiole uniformly areolate, with sculpture weaker on the anterior face of the postpetiole. Gaster smooth and shining, with weak spectral iridescence. Surface of the first gastral sternite smooth and shining.

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. Longer, flexuous setae on the gular region, and the ventrites of the gaster. Short, sparse pubescence present over the entire body, but difficult to detect against the densely sculptured integument.

Color: predominantly medium brown, with mandibles and antennae testaceous yellow. Wing bases, trochanters, meso- and metacoxae, tibiae, tarsi, and sting very light yellow, nearly white.

Male: Unknown.

Etymology: Geographical, from ‘ixil’, one of the many Maya dialects spoken by the indigenous people of Guatemala.

Comments: Temnothorax ixili has been collected from Winkler leaf litter extractions at low elevations in Zacapa state, Guatemala. The type specimens were intercepted in quarantine from Oncidium orchids. The presence of a gyne in a leaf litter extract suggests that this species may nest terrestrially, or at least is not strictly arboreal like many of the salvini clade species.

Figures

Figure 114 Geographical and elevational distribution of the goniops group. (A) Temnothorax achii sp. nov. (B) T. goniops (C) T. ixili (D) T. xincai 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. Map for T. huehuetenangoi not included due to the uncertainty of the collection locality. Full-size DOI: 10.7717/peerj.11514/fig-114

Figure 118 Temnothorax ixili. (A–C) Worker (CASENT0611678). (A) Full-face. (B) Profile view. (C) Dorsal view. (D–F) Gyne (CASENT0611679). (D) Full-face. (E) Profile view. (F) Dorsal view. Scale bars 0.2 mm. Full-size DOI: 10.7717/peerj.11514/fig-118