Temnothorax skwarrae ( Wheeler, 1931 )

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 : 169-174

Temnothorax skwarrae ( Wheeler, 1931)

Distribution: Fig. 107D ; worker & gyne: Fig. 113 .

Macromischa skwarrae Wheeler, 1931: 10 . Syntype workers and gyne. Cuernavaca, Mexico. One syntype worker here designated lectotype.

Leptothorax skwarrae (Wheeler) : Baroni Urbani, 1978: 503. First combination in Leptothorax .

Temnothorax skwarrae (Wheeler) : Bolton, 2003: 272. First combination in Temnothorax .

Type material examined: Lectotype worker: MEXICO: Morelos: Cuernavaca , 26 June 1929, E. Skwarra #Z857a/ Sk. 1 worker (M.C. Z. co-type 10 16358, MCZENT00016358) [ MCZC].

Paralectotype workers and gyne: same data as previous, except: E. Skwarra #Z879/ Sk., ex Tillandsia circinnata , 1 dealate gyne (M.C. Z. co-type 916358, MCZENT00577117) [ MCZC] ; same data as previous, except: E. Skwarra #Z877, ex Tillandsia circinnata , 1 worker (images of FoCol 0411 examined on antweb.org) [ SMND] 1 teneral worker (images of FoCol 0412 examined on antweb.org) [ SMND] ; same data as previous, except: E. Skwarra #Z807a/ Sk., ex Tillandsia circinnata (images of M.C. Z. cotype 4-5 16358, S.N.M.U. type no. co 59607, USNMENT00532047 examined on the Smithsonian National Museum of Natural History Department of Entomology Collections website) [ USNM] .

Geographic distribution: Mid elevations of south-central Mexico (Morelos) ( Fig. 107D ).

Worker diagnosis: Temnothorax skwarrae can be separated from all other species in the salvini clade by the following character combination: antennal scapes short: failing to reach the posterior margin of the head by about the maximum width of the antennal scape (SI 92); body elongate (WLI> 150); metanotal groove not strongly impressed; propodeal spines directed posterodorsally, never directly upward; propodeal spines short, much shorter than the length of the propodeal declivity (PSI 18); hind femora strongly incrassate (FI> 350); petiolar node low, elongate and rounded dorsally (NI 244); postpetiole narrow: greater than one and a half times as wide as the petiole in dorsal view, but less than 2 times as wide (PWI 198); setae on head, mesosoma, waist segments and gaster erect, moderately long, moderately dense and blunt (never long and tapering); integument bicolored: dark brown with a yellow gaster.

Similar species: Temnothorax acutispinosus sp. nov., T. subditivus , T. tenuisculptus , T. tuxtlanus sp. nov., species of the annexus , augusti , fuscatus , and salvini groups. Temnothorax skwarrae can be distinguished from T. tuxtlanus sp. nov. by the incrassate femora (FI <280 in T. tuxtlanus sp. nov.). The low, elongate petiolar node (NI> 180) will separate T. skwarrae from all species listed above, aside from the salvini group and most other members of the fuscatus group. The moderately long, blunt-tipped setae will separate T. skwarrae from the species of the salvini group, which have long, tapering setae. The short propodeal spines, which are much shorter than the propodeal declivity, as well as the bicolored integument, will distinguish T. skwarrae from T. fuscatus and T. nebliselva sp. nov., which have longer propodeal spines and are uniformly colored. Temnothorax skwarrae can be separated from T. ocarinae by the relatively large, oval compound eye, which is about as long as the distance between the compound eye and the mandibular insertion (shorter than the distance between the compound eye and mandibular insertion in T. ocarinae ). Furthermore, T. skwarrae has a bright yellow gaster, as opposed to medium brown in T. ocarinae .

Worker measurements & indices (n = 1): SL = 0.737; FRS = 0.247; CW = 0.857; CWb = 0.804; PoOC = 0.387; CL = 0.965; EL = 0.219; EW = 0.174; MD = 0.218; WL = 1.270; SPST = 0.231; MPST = 0.368; PEL = 0.388; NOL = 0.342; NOH = 0.140; PEH = 0.248; PPL = 0.264; PPH = 0.291; PW = 0.558; SBPA = 0.164; SPTI = 0.189; PEW = 0.177; PNW = 0.145; PPW = 0.350; HFL = 0.880; HFWmax = 0.255; HFWmin = 0.069; CS = 1.287; ES = 0.306; SI = 92; OI = 24; CI = 83; WLI = 158; SBI = 20; PSI = 18; PWI = 198; PLI = 147; NI = 244; PNWI = 82; NLI = 88; FI = 370.

Worker description: In full-face view, head subquadrate, longer than broad (CI 83). 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 weakly emarginate medially. Antennal scapes short: when fully retracted, failing to reach the posterior margin of the head capsule by about the width of the antennal scape (SI 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 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 very weakly concave but rounding evenly into the lateral margins.

In profile view, compound eyes ovular and moderately large (OI 24), with 14 ommatidia in longest row. Pronotal declivity distinct, neck and anterior face of pronotum forming a rounded ~90 ° angle; transition between the anterior and dorsal faces delimited by a transverse carina. Dorsal face of pronotum evenly rounding into the rest of the mesosoma, which is flat to 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. 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 18), about a third as long as the propodeal declivity, tapering evenly from the base, weakly downcurved, and acute. Propodeal declivity weakly concave, forming a rounded ~120 ° angle with the base of the propodeal spines. Propodeal lobes dorsally angulate and small. Metapleural gland bulla small, extending from the metacoxal insertion halfway to the propodeal spiracle. Petiole moderately long (PLI 147), with tubercles anterodorsally. Subpetiolar process in the form of a very small, blunt tooth; ventral margin of petiole flat posterior to it. Petiolar peduncle short: comprising about a quarter of the total length of the petiole. Petiolar node low and dorsally rounded transition between peduncle and node an even grade, resulting in a weakly concave anterior node face; anterior face meeting the dorsal face at a rounded ~120 ° angle; dorsal face rounding evenly into the posterior face. Postpetiole long; anterior and dorsal faces forming an even convexity; lobed ventrally.

In dorsal view, humeri developed and distinct: evenly rounded and 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. 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 weakly diverging apically, their apices separated from each other by about their length, the negative space between them broadly “U” shaped. Petiolar peduncle with spiracles not protruding past the lateral margins. Petiolar node ovular, slightly longitudinally elongate, and narrowed anteriorly; node the same width as the peduncle and the caudal cylinder. Postpetiole narrow (PWI 198) and campaniform. Anterior margin of the postpetiole convex and evenly rounds into the lateral margins, which are parallel to each other; posterior corners angulate; posterior margin weakly emarginate medially. Metafemur strongly incrassate (FI 370).

Sculpture: median clypeal carina present, extending posteriorly nearly to the frontal triangle, and flanked on either side by two equally strong carinae. Lateral clypeal lobes with additional, weaker carinae; ground sculpture areolate. Antennal scapes areolate. Cephalic dorsum densely areolate, with overlying reticulate sculpture; cross-reticulations weaker between the frontal carinae. Lateral surfaces of head densely areolate, with dense reticulate sculpture overlying the ground sculpture. Ventral surface of head longitudinally coarsely areolate-costulate. Pronotal neck areolate. Lateral surface of the mesosoma densely, finely areolate, with coarse longitudinal striae overlying the ground sculpture. Propodeal declivity weakly transversely areolate-costulate. Dorsal surface of mesosoma densely areolate, with coarse rugose sculpture overlying the ground sculpture on the pronotum and propodeum; mesonotal area without overlying sculpture. Femora areolate. Petiole densely areolate, with a coarse longitudinal carina extending from the anterodorsal flange to the caudal cylinder; reticulate sculpture overlying the areolate ground sculpture dorsal to the carina. Postpetiole densely areolate, with reticulate sculpture overlying the ground sculpture. First gastral sternite uniformly weakly areolate, with weak spectral iridescence. First gastral sternite smooth and shining, without spectral iridescence.

Setae: antennal scapes and funiculi with short, decumbent pilosity. Dorsum of the head, pronotum, waist segments, and gaster with sparse, erect, blunt-tipped setae, the longest of which are about the length of the compound eye. The head bears ~34, mesosoma ~30, petiole 8, postpetiole ~16, and first gastral tergite ~30 setae. Short, sparse pubescence present over the entire body, but difficult to detect against the densely sculptured integument.

Color: bicolored. Predominantly dark brown, with a testaceous yellow gaster. Mandibles and legs testaceous brown.

Gyne measurements & indices (n = 1): SL = 0.751; FRS = 0.335; CW = 1.056; CWb = 1.005; PoOC = 0.456; CL = 1.121; EL = 0.286; EW = 0.217; MD = 0.220; WL = 1.881; SPST = 0.430; MPST = 0.497; PEL = 0.525; NOL = 0.287; NOH = 0.239; PEH = 0.387; PPL = 0.379; PPH = 0.437; PW = 1.018; SBPA = 0.417; SPTI = 0.392; PEW = 0.263; PNW = 0.186; PPW = 0.576; HFL = 0.979; HFWmax = 0.267; HFWmin = 0.078; CS = 1.566; ES = 0.395; SI = 75; OI = 25; CI = 90; WLI = 187; SBI = 41; PSI = 23; PWI = 219; PLI = 139; NI = 120; PNWI = 71; NLI = 55; FI = 342.

Gyne description: In full-face view, head subquadrate, longer than broad (CI 90). 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 short: when fully retracted, failing to reach the posterior margin of the head capsule by about three times the maximum width of the scape (SI 75). Antennae 12-segmented; antennal club 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 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 convex posterior to the compound eyes, flat 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 moderately large (OI 25), with 17 ommatidia in longest row. Mesoscutum rounded evenly anteriorly, not fully covering the dorsal surface of the pronotum, and flat dorsally. Mesoscutellum on the same level as the mesoscutum but sloping posteriorly. Metanotum on the same plane as the mesoscutellum. 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 23), about a third as long as the propodeal declivity, tapering evenly from the base, directed posterodorsally, straight, and acute. Propodeal declivity straight and flat, forming a rounded ~110 ° angle with the base of the propodeal spines. Propodeal lobes dorsally angulate and small. Metapleural gland bulla moderately large, extending from the metacoxal insertion two thirds of the way to the propodeal spiracle. Petiole moderately long (PLI 139), with tubercles anterodorsally. Subpetiolar process in the form of a small, acute tooth, which grades evenly into the ventral margin of the petiole posteriorly. Petiolar peduncle short: comprising less than a quarter of the total length of the petiole. Petiolar node erect and cuneiform: transition between peduncle and node evenly rounded, resulting in a concave anterior node face; anterior face forming a very sharp ~90 ° angle with the dorsal face, which rounds evenly into the posterior face. Caudal cylinder long, about one and a half times the maximum width of the antennal scape. Postpetiole evenly rounded anterodorsally, bulging slightly before it transitions into the flattened dorsal face; ventral surface lobed.

In dorsal view, mesoscutum not fully covering the pronotum anteriorly; humeri visible laterally as angulate sclerites. Propodeal spines flat dorsally, weakly diverging apically, their apices separated from each other by about two times their length. Petiolar peduncle with spiracles not protruding past the lateral margins. Petiolar node, when viewed posterodorsally, subquadrate: apex narrower apically than the base, which is the same width as the caudal cylinder and peduncle. Postpetiole moderately broad (PWI 219) and campaniform. Anterior margin of postpetiole convex, rounding evenly into the lateral margins, which are parallel to each other; posterior corners angulate; posterior margin flat. Metafemur strongly incrassate (FI 342).

Sculpture: median clypeal carina present, extending from the anterior margin nearly to frontal triangle, and flanked by two equally strong carinae; lateral margins of median clypeal lobe with two carinae that are as strong as the median carina. Lateral clypeal lobes with additional weaker carinae; ground sculpture finely areolate. Antennal scapes areolate-costulate. Cephalic dorsum densely areolate, with overlying rugose sculpture, becoming costate between the frontal carinae. Lateral surfaces of head densely areolate, with dense predominantly costate sculpture overlying the ground sculpture. Ventral surface of head areolate-costulate. Pronotal neck areolate. Pronotum areolate anteriorly, lateral face areolate, with coarse costae overlying the ground sculpture. Anepisternum and katepisternum shining on their anterior quarters, transitioning into areolate-costulate sculpture posteriorly. Metapleuron and propodeum costate. Propodeal declivity weakly areolate. Mesoscutum and mesoscutellum costate, with areolate-rugulose sculpture between them. Metanotum areolate. Dorsum of propodeum strigulate over areolate ground sculpture. Femora weakly areolate. Petiole weakly areolate ventrally, as well as on the dorsal surface of the peduncle and node; coarse longitudinal carina extending from the anterodorsal flange to the caudal cylinder; rugose sculpture overlying the areolate ground sculpture dorsal to the carina. Postpetiole areolate, with concentric costulae overlying the ground sculpture. First gastral tergite densely, finely areolate, without spectral iridescence. Surface of the first gastral sternite smooth and shining, without spectral iridescence.

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

Color: bicolored. Predominantly dark brown, with a testaceous yellow gaster. Mandibles and legs testaceous brown.

Male: Unknown.

Etymology: Matronym, named for Elizabeth Skwarra, who collected the type series.

Comments: The type series of Temnothorax skwarrae was collected from the epiphyte Tillandsia circinnata near Cuernavaca in Morelos state, Mexico. Very little is known about the biology of this species, but it resembles T. ocarinae from Jalisco state, and the cloud forest species T. fuscatus , which has a range in Central America from south of the Isthmus Tehuantepec to Costa Rica. This species, like T. fuscatus , is apparently arboreally nesting. Temnothorax skwarrae has also been reported from tropical dry forest habitat in Estacion de Biologia Chamela in Jalisco state (Dáttilo et al., 2020), but I have not personally investigated the specimens, so I exclude them here.

Figures

Figure 107 Geographical and elevational distribution of the fuscatus group. (A) Temnothorax fuscatus (B) T. nebliselva sp. nov. (C) T. ocarinae (D) T. skwarrae. 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-107

Figure 113 Temnothorax skwarrae. (A–C) Lectotype worker (MCZENT00016358). (A) Full-face view. (B) Profile view. (C) Dorsal view. (D–F) Paralectotype gyne (MCZENT00577117). (D) Full-face view. (E) Profile view. (F) Dorsal view. Scale bars 0.2 mm. Full-size DOI: 10.7717/peerj.11514/fig-113