Temnothorax harlequina

Temnothorax harlequina is only known from the type locality, Parque Nacional del Este, where a nest was located in a dead, dry stick on top of the leaf litter in dry forest. Stefan Cover noted that where the workers were foraging there was a similarly bicolored salticid spider present. This color scheme is apparently common among the arthropods of Hispaniola and montane Mesoamerica: for example, among the ant species Pheidole harlequina, Linepithema keiteli, Cephalotes flavigaster, Cephalotes unimaculatus, and an undescribed species of Crematogaster display a similar pattern on Hispaniola (see here); in montane Honduras, Pheidole balatro, Pheidole zannia, Brachymyrmex bicolor and Tapinoma JTL 003 exhibit similar coloration (J. T. Longino, 2021, personal communications). The biology of this species remains unknown but is likely to be similar to other members of the ground or litter nesting, pan-Caribbean T. pulchellus group. (Prebus 2021)

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

This species is clearly closely-related to other terricolous Antillean species, namely Temnothorax albispinus, Temnothorax wettereri, Temnothorax pulchellus, Temnothorax magnabulla, and Temnothorax laticrus (Prebus, in prep.). However, it is morphologically similar to members of the flavidulus complex, which are apparently restricted to the island of Hispaniola and its smaller outlying islands.

Temnothorax harlequina can be separated from all other species in the salvini clade by the following character combination: head in full face view with posterior margin slightly convex; antennal scapes moderately long, surpassing the posterior margin of the head by about the maximum width of the antennal scape; anterior margin of the clypeus evenly convex; compound eyes relatively small, with eleven ommatidia in the longest row; in profile view, dorsum of mesosoma evenly, strongly convex; pronotal declivity indistinct; metanotal groove not impressed; propodeum not depressed below the level of the promesonotum; propodeum bearing standing setae dorsally; propodeal spines longer than the propodeal declivity, directed posteriorly, and slightly upturned; hind femora weakly to moderately incrassate; petiolar node flat and elongate dorsally; transition of dorsal to posterior face of petiolar node marked by a rounded angle; in dorsal view, apex of petiolar node narrower or slightly wider than the caudal cylinder of the petiole; postpetiole very broad: greater than or equal to 2.2 times the width of the petiole; dorsum of head smooth and shining; on the anterior margin of the clypeus, setae flanking the central pair are about the same width as the central pair; petiolar node with four 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 lateral lobes of the clypeus, mandibles and antennae), mesosoma (except for the pronotal neck and propodeal spines), metafemora (except for the proximalmost third) and waist segments medium brown; otherwise very light yellow.

Similar species: Temnothorax ciferrii, Temnothorax flavidulus, Temnothorax hippolyta, Temnothorax magnabulla, Temnothorax pulchellus and Temnothorax terricola. The bicolored integument of T. harlequina, with its light yellow gaster, is unique within the pulchellus group and will distinguish T. harlequina from any similar species. Additionally, the erect setae count of four on the dorsum of the petiolar node differentiates T. harlequina from T. terricola and T. hippolyta, which have only two along the posterior margin. The flat relatively small compound eyes, with eleven ommatidia in the longest row, and bicolored integument separate T. harlequina from T. flavidulus, which has 12 ommatidia in the longest row of the compound eye and is uniformly light yellow. The presence of erect setae on the propodeum distinguishes T. harlequina from T. pulchellus. The strongly convex dorsal margin of the mesosoma and angulate transition between the dorsal and posterior faces of the petiolar node distinguishes T. harlequina from T. magnabulla, in which the mesosoma is flatter and the petiolar node transition is evenly rounded. Temnothorax ciferrii and T. harlequina can be separated most easily by the color of the integument: T. harlequina has a light yellow gaster, whereas the gaster of T. ciferrii is always dark brown, or brown with the anterior quarter of the first gastral tergite yellowish. The structure of the clypeus may also be used to separate the two species: T. harlequina has an evenly convex anterior margin of the clypeus, whereas T. ciferrii has a medially flattened anterior clypeal margin. The medial two pairs of setae on the anterior clypeus margin may also be used to separate T. harlequina and T. ciferrii: in T. ciferrii, the setae flanking the central pair are thickened to nearly twice the width of the central pair, whereas in T. harlequina they are nearly the same width.

Distribution
Low elevation in Western Hispaniola (La Altagracia Province, Dominican Republic).

Distribution based on Regional Taxon Lists
Neotropical Region: Dominican Republic.

Nomenclature

 * . Temnothorax harlequina Prebus, 2021: 300, figs. 133G, 141 (w.) DOMINICAN REPUBLIC.

Worker
(n = 9): SL = 0.438-0.504 (0.467); FRS = 0.170-0.220 (0.195); CW = 0.475-0.574 (0.533); CWb = 0.432-0.524 (0.483); PoOC = 0.204-0.235 (0.220); CL = 0.496-0.595 (0.555); EL = 0.113-0.138 (0.126); EW = 0.088-0.107 (0.100); MD = 0.112-0.159 (0.13); WL = 0.550-0.661 (0.608); SPST = 0.226-0.283 (0.255); MPST = 0.183-0.213 (0.195); PEL = 0.248-0.304 (0.278); NOL = 0.131-0.166 (0.151); NOH = 0.090-0.111 (0.102); PEH = 0.172-0.199 (0.185); PPL = 0.134-0.166 (0.153); PPH = 0.170-0.215 (0.192); PW = 0.323-0.393 (0.361); SBPA = 0.115-0.165 (0.141); SPTI = 0.243-0.301 (0.269); PEW = 0.116-0.150 (0.137); PNW = 0.127-0.170 (0.145); PPW = 0.284-0.355 (0.319); HFL = 0.403-0.485 (0.447); HFWmax = 0.112-0.132 (0.122); HFWmin = 0.042-0.057 (0.047); CS = 0.680-0.822 (0.751); ES = 0.157-0.190 (0.174); SI = 92-101 (97); OI = 23-25 (23); CI = 85-88 (87); WLI = 123-128 (125); SBI = 27-31 (29); PSI = 40-45 (42); PWI = 222-245 (234); PLI = 161-196 (182); NI = 128-169 (147); PNWI = 93-116 (105); NLI = 50-62 (54); FI = 230-300 (257).

In full-face view, head subquadrate, longer than broad (CI 85-88). 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 rounded. 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 92-101). Antennae 12-segmented; antennal club of three segments, with the apical-most segment slightly longer than the preceding two in combination. Frontal carinae short, extending past the antennal toruli by about 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 weakly convex, rounding evenly into the lateral margins.

In profile view, compound eyes ovular and moderately large (OI 23-25), with 11 ommatidia in longest row. Pronotal declivity indistinct, neck and anterior face of pronotum forming a ~130° angle. Mesosoma evenly convex from where it joins the neck to the propodeal spines. Promesonotal suture extending from the posterior margin of the coxal insertion only to the mesothoracic spiracle, which is 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. Propodeal spiracle well developed, directed posterolaterally, and separated from the propodeal declivity by about two and a half spiracle diameters. Propodeal spines well developed and long (PSI 40-45), about one and a half times the length of the propodeal declivity, tapering evenly from the base, straight for most of their length but slightly upturned at the tips, and acute. Propodeal declivity straight and flat, forming a ~110° angle with the base of the propodeal spines. Propodeal lobes rounded and weakly developed. Metapleural gland bulla small, extending from the metacoxal insertion a quarter of the way to the propodeal spiracle. Petiole moderately long (PLI 161-196), without tubercles anterodorsally. Subpetiolar process in the form of a very small, acute tooth; ventral margin of the petiole slightly concave posterior to it. Petiolar peduncle short: most of the dorsal surface of the petiole composed of the node. Petiolar node robust: transition between peduncle and node evenly rounded, resulting in a very weakly concave anterior node face; anterior face forming a ~120° angle with the dorsal face, which is long, weakly convex, and nearly flat; dorsal face forming a ~100° angle with the short posterior face, which forms a ~130° angle with the caudal cylinder. Postpetiole evenly rounded anteriorly, flat dorsally, and weakly lobed ventrally.

In dorsal view, humeri developed and distinct: evenly rounded and wider than 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. Metanotal groove absent: mesonotum and propodeum completely fused and converging evenly to the bases of the propodeal spines. Propodeal spines closely approximated basally and strongly diverging apically, their apices separated from each other by about their length; negative space between them in the form of a "U". Petiolar peduncle with spiracles slightly protruding past the lateral margins, peduncle not noticeably constricted anterior to them. Petiolar node evenly rounded, slightly wider than the peduncle, and evenly grading into the caudal cylinder, which is slightly wider than the node. Postpetiole very broad (PWI 222-245) and campaniform, articulating with nearly the entire anterior margin of the gaster. Anterior margin of the postpetiole broadly convex, with the corners evenly rounding into the lateral margins, which diverge to the angulate posterior corners; posterior margin medially emarginate. Metafemur weakly to moderately incrassate (FI 230-300).

Sculpture: median clypeal carina present, extending posteriorly to the level of the antennal insertions. Lateral clypeal lobes with additional, weaker carinae; ground sculpture smooth and shining. Antennal scapes shining through weak ground sculpture. Cephalic dorsum smooth and shining, with weak sculpture near the anterior margins of the compound eye. Pronotal neck areolate. Mesosoma with lateral face of the pronotum, mesopleurae, metapleurae and propodeal declivity areolate; otherwise smooth and shining. Femora shining through weak areolate sculpture. Petiole smooth and shining ventrally, with very weak areolate sculpture on the peduncle and the lateral surfaces of the petiolar node; the dorsal surface of the smooth and shining. Postpetiole entirely smooth and shining. Gaster smooth and shining, without spectral iridescence.

Setae: antennal scapes and funiculi with adpressed pilosity. Dorsum of head, pronotum, waist segments and gaster with abundant, erect, blunt-tipped setae, the longest of which are about the width of the compound eye. The head bears ~22, mesosoma ~18, petiole 4, postpetiole ~10, and first gastral tergite ~8 setae. Pubescence present on the entire body but more difficult to detect on lightly colored surfaces.

Color: strongly bicolored: head (except for the lateral lobes of the clypeus, mandibles and antennae), mesosoma (except for the pronotal neck and propodeal spines), metafemora (except for the proximalmost third) and waist segments medium brown. Otherwise very light yellow.

Type Material
Holotype worker: DOMINICAN REPUBLIC: La Altagracia: Parque Nacional del Este, Caseta de Guaraguao,, 10 m, 30 March 2004, S.P. Cover #SPCDR-151, evergreen coastal forest 5-10 m tall on coralline rock, relatively undisturbed native vegetation, nest fragment in dead, dry stick 2 cm in diameter on litter surface in shade; dense, shady tree clump to 6 m tall (CASENT0756091).

Paratype workers: same data as holotype, 1 worker (CASENT0758822) [MCZC] 1 worker (CASENT0758823) [MCZC] 1 worker (CASENT0758824) ; same data as holotype, except: S.P. Cover #SPC DR-152, evergreen coastal forest 5-10 m tall on coralline rock; relatively undisturbed native vegetation; nest fragment in dead, dry stick 2 cm in diameter on litter surface in shade; dense, shady tree clump to 6 m tall, 1 worker (CASENT0756156) [MCZC] 1 worker (CASENT0758709) 1 worker (CASENT0758825)  1 worker (CASENT0758826)  1 worker (CASENT0758827)  1 worker (MCZENT00531354) [MCZC] 1 worker (MCZENT00531355) [MCZC].

Etymology
Morphological, from obsolete French: Harlequin, a pantomime fool with brightly colored clothing. The specific epithet refers to the similarity in color pattern to the sympatric ant species Pheidole harlequina.