Temnothorax pulchellus

Temnothorax pulchellus is known only from the British and U.S. Virgin Islands of Guana and St. John, respectively, both of which are a mixture of tropical xeric scrubland and tropical moist forest. The biology of this species is unknown but is likely to be similar to other members of the Antillean, terricolous pulchellus group. (Prebus 2021)

Identification
Prebus (2021) – A member of the  pulchellus species group of the Temnothorax salvini clade.

This species is closely related to other terricolous Antillean species, namely Temnothorax albispinus, Temnothorax harlequina, Temnothorax laticrus Temnothorax magnabulla, and Temnothorax wettereri

Temnothorax pulchellus can be separated from all other species in the salvini clade by the following character combination: in profile view, dorsum of mesosoma not strongly convex; pronotal declivity indistinct; metanotal groove not impressed; propodeum not depressed below the level of the promesonotum; propodeum not bearing standing setae dorsally; propodeal spines longer than propodeal declivity, directed posterodorsally, and slightly downcurved; hind femora weakly to moderately incrassate; in dorsal view, apex of petiolar node narrower to slightly broader the caudal cylinder of the petiole; postpetiole very broad: greater than or equal to 2.4 times the width of the petiole; dorsum of head smooth and shining; petiolar node with two erect setae dorsally; setae on head, mesosoma, waist segments and gaster erect, moderately long, sparse and blunt (never long and tapering); integument bicolored: head (except for the clypeus and mandibles) and gaster dark brown; rest of body pale yellow.

Similar species: Temnothorax ciferrii, Temnothorax harlequina, Temnothorax hippolyta, and Temnothorax terricola. The erect setae count of two on the dorsum of the petiolar node differentiates T. pulchellus from T. harlequina and T. ciferrii, which have four dorsally. The absence of erect setae on the propodeum distinguishes T. pulchellus from T. hippolyta and T. terricola, as well as the long propodeal spines.

Distribution based on Regional Taxon Lists
Neotropical Region: British Virgin Islands, Lesser Antilles, United States Virgin Islands.

Nomenclature

 *  pulchellus. Macromischa pulchella Emery, 1894c: 162 (w.q.) ANTILLES. Combination in M. (Antillaemyrmex): Mann, 1920: 408; in Antillaemyrmex: Wheeler, W.M. 1931b: 32; in Leptothorax: Baroni Urbani, 1978b: 482; in Temnothorax: Bolton, 2003: 272.

Description
Prebus (2021) - Both Baroni Urbani (1978) and Emery (1894) note that the workers of this species are very small; this observation may have been biased by the small amount of material available to them (e.g. Baroni Urbani, 1978 only observed one worker syntype). During this revision, I was able to look at two additional nest series, and the variation in the size of the workers of T. pulchellus (WL 0.521-0.690) appears to be similar to that of Temnothorax albispinus (WL 0.608-0.715).

Worker
Prebus (2021) - (n = 9): SL = 0.382-0.516 (0.470); FRS = 0.163-0.211 (0.195); CW = 0.457-0.603 (0.547); CWb = 0.407-0.542 (0.493); PoOC = 0.189-0.263 (0.236); CL = 0.492-0.635 (0.586); EL = 0.108-0.141 (0.129); EW = 0.075-0.104 (0.096); MD = 0.118-0.158 (0.136); WL = 0.521-0.690 (0.629); SPST = 0.169-0.262 (0.224); MPST = 0.169-0.222 (0.206); PEL = 0.229-0.337 (0.295); NOL = 0.140-0.193 (0.170); NOH = 0.096-0.129 (0.115); PEH = 0.165-0.212 (0.193); PPL = 0.158-0.205 (0.188); PPH = 0.185-0.243 (0.214); PW = 0.286-0.385 (0.351); SBPA = 0.123-0.156 (0.143); SPTI = 0.170-0.225 (0.208); PEW = 0.119-0.154 (0.138); PNW = 0.106-0.152 (0.132); PPW = 0.299-0.395 (0.356); HFL = 0.383-0.502 (0.455); HFWmax = 0.105-0.140 (0.129); HFWmin = 0.039-0.057 (0.049); CS = 0.653-0.860 (0.786); ES = 0.146-0.193 (0.178); SI = 94-97 (95); OI = 22-26 (23); CI = 82-86 (84); WLI = 126-131 (128); SBI = 27-31 (29); PSI = 31-39 (36); PWI = 242-273 (258); PLI = 135-177 (157); NI = 131-161 (148); PNWI = 89-104 (95); NLI = 53-65 (58); FI = 232-298 (265).

In full-face view, head subquadrate, longer than broad (CI 82-86). Mandibles weakly striate, 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 entire and evenly convex medially. Antennal scapes moderately long: when fully retracted, extending past the posterior margin of the head capsule by about the maximum width of the scape (SI 94-97). Antennae 12-segmented; antennal club of three segments, with the apical-most segment slightly longer than the preceding two in combination. Frontal carinae very short, extending past the antennal toruli by 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, forming a continuous arc from the posterior of the head to the mandibular insertions. Posterior head margin flat to very slightly convex, rounding evenly into the lateral margins.

In profile view, compound eyes ovular and moderately large (OI 22-26), with 11 ommatidia in longest row. Pronotal declivity indistinct, neck and anterior face of pronotum forming a rounded ~140° angle. Mesosoma convex dorsally from where it joins the pronotal neck to the propodeal spines. Promesonotal suture extending from the posterior margin of the procoxal insertion only to the mesothoracic spiracle, which is well developed. Metanotal groove visible in profile in some specimens as a small concavity between the promesonotum and propodeum; visible in all specimens as a faint disruption in the surface sculpture between meso- and metacoxal insertions to the minute metathoracic spiracle. Propodeal spiracle well developed, directed posterolaterally, and separated from the propodeal declivity by about three spiracle diameters. Propodeal spines well developed and moderately long (PSI 31-39), about as long as the propodeal declivity, tapering evenly from the base, and acute. 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 halfway to the propodeal spiracle. Petiole moderately long (PLI 135-177), without tubercles anterodorsally where it articulates with the mesosoma. Subpetiolar process in the form of a small, blunt tooth, which grades evenly into the ventral margin of the petiole posteriorly; ventral surface of petiole slightly concave posterior to the process. Petiolar peduncle moderately long: comprising about half of the total length of the petiole. Petiolar node robust and erect: transition between peduncle and node marked by a rounded angle of ~120°, resulting in a strongly concave anterior node face; anterior face forming a rounded ~100° angle with the dorsal face, which is evenly convex and moderately long; dorsal face rounding evenly into the posterior face, which forms a ~120° angle with the caudal cylinder. Postpetiole evenly rounded dorsally; weakly lobed ventrally.

In dorsal view, humeri weakly developed: rounded and only slightly protruding past 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. Mesonotum and propodeum separated by a very weak depression, their margins converging evenly to the bases of the propodeal spines. Propodeal spines closely approximate basally and diverging apically, their apices separated from each other by slightly more than their length; negative space between them a basally rounded "U". Petiolar peduncle with spiracles protruding past the lateral margins; node oviform and narrowest anteriorly, slightly wider than the peduncle, and evenly grading into the caudal cylinder, which is slightly wider than the node. Postpetiole very broad (PWI 242-273) and campaniform, articulating with the entire anterior margin of the gaster, not leaving anterior corners of gaster exposed. Anterior margin of the postpetiole broadly convex, with corners evenly rounding into the lateral margins, which evenly diverge to the angulate posterior corners; posterior margin broadly concave. Metafemur weakly to moderately incrassate (FI 232-298).

Sculpture: median clypeal carina present, flanked by additional weaker carinae over a smooth and shining ground sculpture. Antennal scapes shining through very weakly areolate ground sculpture. Cephalic dorsum predominantly smooth and shining, except for fine piligerous punctures and weak areolate sculpture posterior to the compound eyes, which extends to the posteroventral surface of the head. Pronotal neck areolate. Mesosoma predominantly smooth and shining dorsally; weak areolate sculpture and rugulae present on the lateral margins of the pronotum, meso-, and metapleurae. Femora shining through very weak traces of areolate sculpture. Peduncle of petiole smooth and shining ventrally, with very shallow areolate sculpture surrounding the base of the petiolar node, which is smooth and shining dorsally. Dorsal surface of postpetiole smooth and shining, with weak areolate sculpture on the posterior margin. Gaster smooth and shining, without spectral iridescence. Surface of the first gastral sternite smooth and shining.

Setae: antennal scapes and funiculi with short, adpressed pilosity. Dorsum of head, pronotum, waist segments and gaster with sparse, short, erect, blunt-tipped setae, the longest of which are slightly less than the width of the compound eye. The head bears ~18, mesosoma ~2, petiole 2, postpetiole ~10, and first gastral tergite ~14 setae. Sparse, adpressed pubescence present on the entire body.

Color: head (except for the clypeus and mandibles) and gaster are dark brown. The rest of the body pale yellow.

Queen
Prebus (2021) - (n = 1): SL = 0.577; FRS = 0.249; CW = 0.750; CWb = 0.690; PoOC = 0.278; CL = 0.707; EL = 0.208; EW = 0.160; MD = 0.168; WL = 1.134; SPST = 0.278; MPST = 0.301; PEL = 0.438; NOL = 0.192; NOH = 0.173; PEH = 0.302; PPL = 0.195; PPH = 0.351; PW = 0.697; SBPA = 0.354; SPTI = 0.349; PEW = 0.210; PNW = 0.212; PPW = 0.580; HFL = 0.611; HFWmax = 0.153; HFWmin = 0.062; CS = 1.044; ES = 0.288; SI = 84; OI = 28; CI = 98; WLI = 164; SBI = 51; PSI = 25; PWI = 276; PLI = 225; NI = 111; PNWI = 101; NLI = 44; FI = 247.

In full-face view, head subquadrate, roughly as long as broad (CI 98). Mandibles weakly striate, 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 very slightly concave medially. Antennal scapes moderately long: when fully retracted, just reaching the posterior margin of the head capsule (SI 84). Antennae 12-segmented; antennal club of three segments, with the apical-most segment as long as the preceding two in combination. Frontal carinae very short, extending past the antennal toruli by one 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 evenly convex, forming a continuous arc from the posterior of the head to the mandibular insertions. Posterior head margin very slightly convex, rounding evenly into the lateral margins.

In profile view, compound eyes ovular and large (OI 28), with 16 ommatidia in longest row. Mesoscutum rounded evenly anteriorly, covering the dorsal surface of the pronotum, and flat dorsally. Mesoscutellum on the same plane as the mesoscutum but inclined posteriorly; posterior margin of mesoscutellum even with the posterior margin of the metanotum. Propodeal spiracle well developed, directed posterolaterally, and separated from the propodeal declivity by about three and a half spiracle diameters. Propodeal spines stout and well developed, but short (PSI 25), about half as long as the propodeal declivity, tapering evenly from the base, straight, and directed posteriorly. Metapleural gland bulla small, extending from the metacoxal insertion halfway to the propodeal spiracle. Propodeal declivity weakly concave, forming a rounded ~100° angle with the base of the propodeal spines. Propodeal lobes rounded and very weakly developed. Petiole long (PLI 225), without tubercles anterodorsally where it articulates with the mesosoma. Subpetiolar process in the form of a weakly developed, acute triangular tooth, which grades evenly into the ventral margin of the petiole posteriorly. Petiolar peduncle moderately long: comprising about half of the total length of the petiole. Petiolar node erect: transition between the peduncle and the node evenly rounded, resulting in a concave anterior node face; anterior face forming a sharp ~90° angle with the dorsal face, which is nearly flat; dorsal face rounding evenly into the posterior face, which forms a ~130° angle with the caudal cylinder. Postpetiole evenly rounded anterodorsally, flattened dorsally; ventral surface lobed.

In dorsal view, mesoscutum covering pronotum anteriorly, but humeri visible laterally as rounded sclerites. Propodeal spines diverging apically, their apices separated from each other by about two times their length. Petiolar peduncle with spiracles protruding past the lateral margins, the peduncle broadened where they arise. Petiolar node weakly convex anteriorly, but forming angles with the lateral margins, its shape roughly trapezoidal. Petiolar node slightly wider than the peduncle, and evenly grading into the caudal cylinder, which is roughly the same width as the node. Postpetiole very broad (PWI 276), anteroposteriorly compressed, and campaniform, articulating with most of the anterior margin of the gaster, leaving small, angulate margins on each side of the gaster exposed. Anterior margin of the postpetiole weakly concave medially, with corners evenly rounding into the lateral margins, which evenly diverge to the angulate posterior corners; posterior margin broadly concave. Metafemur weakly incrassate (FI 247).

Sculpture: median clypeal carina present, but very short and weak: extending from the anterior margin only about a quarter of the way to the frontal triangle; flanked by additional stronger carinae; smooth and shining through weak areolate sculpture medially. Antennal scapes shining through very weakly areolate ground sculpture. Cephalic dorsum shining through traces of costulate ground sculpture; weak areolae present around the antennal insertions and posterior to the compound eyes. Pronotal neck evenly areolate. Lateral surfaces of pronotum with weak areolae and striae, which become stronger ventrally. Anepisternum and katepisternum smooth and shining. Propodeum with weak areolate sculpture and costulae laterally, but smooth and shining between the propodeal spines. Mesoscutum predominantly smooth and shining, but with weak costulae surrounding a medial patch of smooth and shining sculpture. Mesoscutellum smooth and shining, with weak costulate sculpture laterally. Femora smooth and shining, with traces of weak areolate sculpture. Peduncle of petiole smooth and shining ventrally, with shallow areolate sculpture dorsally. Areolate sculpture surrounding the petiolar node, which is smooth and shining dorsally. Dorsal surface of postpetiole smooth and shining, with weak areolate sculpture on the posterior quarter, and lateral surfaces. Gaster smooth and shining, without spectral iridescence. Surface of the first gastral sternite smooth and shining.

Setae: antennal scapes and funiculi with short, adpressed pilosity. Dorsum of head, pronotum, waist segments and gaster with sparse, short, erect, blunt-tipped setae, the longest of which are about half the width of the compound eye. Sparse, adpressed pubescence present on the entire body.

Color: head (except for the clypeus and mandibles), wing bases, and gaster are dark brown. The rest of the body pale yellow.

Type Material
Prebus (2021) - Macromischa pulchella: Syntype worker and gyne. St. Thomas, U.S.Virgin Islands. One syntype worker here designated lectotype.

Lectotype worker of Macromischa pulchella: U.S. VIRGIN ISLANDS: St. Thomas: Eggers, [no collection date], [no collector data] (images of CASENT0904717 examined on antweb.org).

Etymology
Prebus (2021) - Morphological, from the Latin ʻpulchellus' (= pretty little), in reference to the coloration and size of this species.

References based on Global Ant Biodiversity Informatics

 * Baroni Urbani C. 1978. Materiali per una revisione dei Leptothorax neotropicali appartenenti al sottogenere Macromischa Roger, n. comb. (Hymenoptera: Formicidae). Entomol. Basil. 3: 395-618.
 * Brandao, C.R.F. 1991. Adendos ao catalogo abreviado das formigas da regiao neotropical (Hymenoptera: Formicidae). Rev. Bras. Entomol. 35: 319-412.
 * Emery C. 1894. Studi sulle formiche della fauna neotropica. VI-XVI. Bullettino della Società Entomologica Italiana 26: 137-241.
 * Emery C. 1896. Sur les fourmis du genre Macromischa Rog. (Hym.). Bulletin de la Société Entomologique de France 1896: 102-103.
 * Kempf, W.W. 1972. Catalago abreviado das formigas da regiao Neotropical (Hym. Formicidae) Studia Entomologica 15(1-4).
 * Wheeler W. M. 1905. The ants of the Bahamas, with a list of the known West Indian species. Bulletin of the American Museum of Natural History 21: 79-135.
 * Wheeler W. M. 1908. The ants of Porto Rico and the Virgin Islands. Bulletin of the American Museum of Natural History 24: 117-158.
 * Wheeler W. M. 1931. New and little-known ants of the genera Macromischa, Creosomyrmex and Antillaemyrmex. Bulletin of the Museum of Comparative Zoology 72: 1-34.
 * Wheeler W. M. 1937. Ants mostly from the mountains of Cuba. Bulletin of the Museum of Comparative Zoology. 81: 439-465.