Temnothorax flavidulus

Temnothorax flavidulus is only known from the type specimens, collected from under a stone in Manneville, Haiti, which is contemporarily known as Thomazeau. This locality lies in the Hispaniolan rift valley near Étang Saumâtre,, a large, brackish lake. Thomazeau lies in an arid part of the rift valley, and the surrounding area is dominated by dry forest and dry steppe. The biology of this species remains unknown but is likely to be similar to other members of the terricolous pulchellus group. The larger eyes and lightly colored integument are typical of other xerophilic Temnothorax. (Prebus 2021)

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

Temnothorax flavidulus can be separated from all other species in the salvini clade by the following character combination: compound eyes relatively large, with twelve 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 weakly downcurved; hind femora weakly to moderately incrassate; petiolar node flat and elongate dorsally; transition of dorsal to posterior face of petiolar node marked by an 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; 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 predominantly light yellow.

Similar species: Temnothorax agavicola, Temnothorax ciferrii, Temnothorax harlequina, Temnothorax hippolyta, Temnothorax magnabulla, Temnothorax pulchellus and Temnothorax terricola. The erect setae count of four on the dorsum of the petiolar node differentiates T. flavidulus from T. terricola and T. hippolyta, which have only two along the posterior margin. The flat relatively large compound eyes, with twelve ommatidia in the longest row, and light integument separate T. flavidulus from T. ciferrii, which has nine to eleven ommatidia in the longest row of the compound eye and is variously colored, but never light yellow. The presence of erect setae on the propodeum distinguishes T. flavidulus 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. flavidulus from T. magnabulla, in which the mesosoma is flatter and the petiolar node transition is evenly rounded. Temnothorax flavidulus and T. harlequina can be separated most easily by the color of the integument: T. harlequina has a light yellow gaster, which contrasts with a darker mesosoma and head, whereas T. flavidulus is uniformly yellow. The medial two pairs of setae on the anterior clypeus margin may also be used to separate T. harlequina and T. flavidulus: in T. flavidulus, 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. Temnothorax flavidulus may also be confused with T. agavicola, but the head sculpture of this species is areolate, in contrast the smooth and shining sculpture of T. flavidulus.

Wheeler and Mann (1914) - Similar to Temnothorax ciferrii but differing in color and postpetiole; flavidulus yellow, postpetiole in dorsal view (with head at top of view and gaster below) with linear edges anteriorly and along both sides with the latter diverging outward from top to bottom, ciferrii brown to piceus, postpetiole in dorsal view (with head at top of view and gaster below) with anterior edge and sides forming a roughly continuous circular curve.

Distribution based on Regional Taxon Lists
Neotropical Region: Greater Antilles, Haiti.

Nomenclature

 *  flavidulus. Macromischa flavidula Wheeler, W.M. & Mann, 1914: 37, fig. 15 (w.q.) HAITI. Combination in M. (Antillaemyrmex): Mann, 1920: 408; in Antillaemyrmex: Wheeler, W.M. 1931b: 32; in Leptothorax: Baroni Urbani, 1978b: 441; in Temnothorax: Bolton, 2003: 271.

Prebus (2021) - A member of the pulchellus group, sensu Baroni Urbani (1978) and Fontenla Rizo (2000). As noted by Baroni Urbani (1978), this species closely resembles T. ciferrii, which is known only from a few collections in xerophytic habitats of the Dominican Republic. Baroni Urbani (1978) uses the conformation of the postpetiole as a character that distinguishes T. flavidulus from T. ciferrii, with T. flavidulus having more angulate anterior corners of the postpetiole. The depiction of the postpetiole in the Baroni Urbani (1978) is a bit misleading, though: the anterior corners of the postpetiole are not quite as squared as in the drawing, especially when all of the worker specimens are considered. My observations of the types of T. flavidulus offer several more distinguishing characteristics, for example the eye of T. flavidulus is distinctly larger than that of T. ciferrii. Temnothorax flavidulus is part of a large complex of species endemic to the island of Hispaniola and its smaller outlying islands, including Temnothorax bahoruco, Temnothorax balaclava, Temnothorax ciferrii, Temnothorax harlequina, Temnothorax wilsoni, none of which have been collected in sympatry. While it is possible to distinguish T. flavidulus from each of these taxa based on morphology, it remains to be seen whether this putative species is simply a variant of a widespread, morphologically diverse species.

Worker
Length 1.5-1.7 mm.

Head somewhat longer than broad, as broad in front as behind, with evenly convex sides, nearly straight posterior border, rounded posterior corners and the moderately convex eyes at the middle of the sides. Mandibles with rather straight external and finely denticulate apical borders. Clypeus convex, with broadly rounded anterior border. Frontal carinae subparallel; frontal area indistinct. Antennal scapes reaching to the posterior border of the head; club of funiculus large, 3-jointed; remaining joints, except the first, small, broader than long. Thorax short, about as long as the head with the mandibles, a little broader in front than behind, in profile with evenly rounded, convex dorsum, without any traces of promesonotal or mesoepinotal sutures; humeri rounded, epinotum sloping, without distinct base and declivity,bearing two spines which are longer than the declivity and much longer than their distance apart, curved downward and directed backward and outward. Petiole with a short, slender peduncle, bearing a small, acute tooth on its ventral surface, and a node which is longer than broad, with its anterior declivity in profile sloping and slightly concave, its summit slightly flattened and its posterior declivity very short and convex. Postpetiole large, broader than long, three times as broad as the petiole behind, in profile rounded and convex above. Gaster small, at the base only a little broader than the postpetiole. Legs rather short; femora slightly incrassated.

Whole surface of body very smooth and shining.

Hairs white, blunt, short, scattered and erect on the body, very minute and appressed on the scapes and legs.

Yellow; mandibles, antennae, epinotal spines, legs and venter paler and more whitish.

Prebus (2021) - (n = 2): SL = 0.427-0.450 (0.442); FRS = 0.160-0.185 (0.170); CW = 0.492-0.529 (0.506); CWb = 0.444-0.472 (0.454); PoOC = 0.182-0.206 (0.195); CL = 0.530-0.552 (0.537); EL = 0.134-0.145 (0.140); EW = 0.102-0.117 (0.109); MD = 0.123-0.143 (0.138); WL = 0.572-0.604 (0.596); SPST = 0.236-0.272 (0.256); MPST = 0.201-0.249 (0.221); PEL = 0.261-0.302 (0.278); NOL = 0.142-0.176 (0.155); NOH = 0.100-0.111 (0.104); PEH = 0.165-0.185 (0.173); PPL = 0.151-0.194 (0.170); PPH = 0.202-0.229 (0.212); PW = 0.338-0.350 (0.342); SBPA = 0.147-0.164 (0.151); SPTI = 0.231-0.26 (0.240); PEW = 0.130-0.155 (0.139); PNW = 0.136-0.156 (0.143); PPW = 0.325-0.351 (0.342); HFL = 0.405-0.471 (0.433); HFWmax = 0.104-0.132 (0.122); HFWmin = 0.041-0.054 (0.047); CS = 0.712-0.748 (0.723); ES = 0.189-0.201 (0.194); SI = 93-101 (98); OI = 26-27 (27); CI = 83-86 (85); WLI = 124-136 (131); SBI = 32-35 (33); PSI = 41-45 (43); PWI = 223-262 (247); PLI = 156-180 (164); NI = 131-176 (150); PNWI = 91-120 (104); NLI = 51-60 (56); FI = 231-298 (262).

In full-face view, head subquadrate, longer than broad (CI 83-86). Mandibles weakly striate, shining, and armed with five teeth: the apical-most well developed, followed by a smaller preapical tooth, which is followed by 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 93-101). Antennae 12-segmented; antennal club 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 evenly convex, forming a continuous arc from the posterior of the head to the mandibular insertions. Posterior head margin flat, rounding evenly into the lateral margins.

In profile view, compound eyes ovular and moderately large (OI 26-27), with 12 ommatidia in longest row. Pronotal declivity indistinct, neck and anterior face of pronotum forming a ~120° angle. Mesosoma evenly rounded 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 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 poorly developed, directed posterolaterally, and separated from the propodeal declivity by about three spiracle diameters. Propodeal spines well developed and long (PSI 41-45), about one and a half times as long as the propodeal declivity, tapering evenly from the base, weakly downcurved, and acute. Propodeal declivity straight and flat, forming a rounded ~90° 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 156-180), without tubercles anterodorsally. Subpetiolar process in the form of a small, acute tooth; ventral margin of petiole weakly concave posterior to it. Petiolar peduncle short: petiolar node covering most of the petiolar dorsum. Petiolar node robust: grading evenly into the petiolar peduncle anteriorly, resulting in a weakly concave anterior node face; anterior margin forming a ~120° angle with the dorsal face, which is long and weakly convex, nearly flat; dorsal face forming a ~110° angle with the short posterior declivity. Postpetiole evenly rounded anteriorly, flattened dorsally, and weakly 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 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 two thirds their length; negative space between them "U" shaped. Petiolar node evenly ovate and narrowest anteriorly, but transition from dorsal to anterior face indistinct; node slightly wider than the peduncle, and evenly grading into the caudal cylinder, which is slightly wider than the node. Postpetiole very broad (PWI 223-262) and campaniform, articulating with nearly the entire anterior margin of the gaster. Anterior margin of the postpetiole broadly convex, nearly flat, with the corners evenly rounding into the lateral margins, which diverge to the angulate posterior corners; posterior margin broadly concave, nearly flat. Metafemur weakly to moderately incrassate (FI 231-298).

Sculpture: median clypeal carina present, extending posteriorly nearly to the level of the antennal toruli, and flanked on either side by two equally strong carinae. Lateral clypeal lobes with additional, weaker carinae; ground sculpture smooth and shining. Antennal scapes shining through weak areolate ground sculpture. Cephalic dorsum smooth and shining, with weak areolate sculpture on the posterolateral surface of the head, behind the compound eyes. Pronotal neck areolate. Mesosoma with weak and indistinct sculpture on the posterodorsal surface of the pronotum, weak costulae on the lateral margin of the pronotum, and weak areolate sculpture on the mesopleurae, metapleurae and lateral surfaces of the propodeum; otherwise smooth and shining. Femora smooth and shining through weak areolate sculpture. Petiole smooth and shining ventrally, with very weak areolate sculpture on all other surfaces. Postpetiole entirely smooth and shining, with weak areolate sculpture on the posterior quarter. Gaster smooth and shining, without spectral iridescence.

Setae: antennal scapes and funiculi with short, adpressed pilosity. Dorsum of head, pronotum, waist segments and gaster with sparse, erect, blunt-tipped setae, the longest of which are about the width of the compound eye. The head bears ~12, mesosoma ~8, petiole 4, postpetiole ~6, and first gastral tergite ~10 setae. Short, sparse pubescence present over the entire body, but difficult to detect against the lightly colored integument.

Color: entirely light yellow, except for the slightly infuscated masticatory margin of the mandible.

Baroni Urbani (1978) - Capo moderatamente allungato a lati pressoche diritti. Mandibole subtriangolari a margine masticatorio armato di 5-6 denti piccoli e poco appuntiti. Occhi fortemente aggettanto sui lati. Scapo debolmente ricurvo e breve: ripiegato all'indietro esso raggiunge appena il margine occipitale. Alitronco a profilo dorsale tondeggiante, senza nessun accenno di sutura visibile. Solo la sutura promesotoracica visibile sui lati. Spine propodeali lunghe e gracili, debolmente divergenti e curvate verso il basso. Peziolo globoso e brevemente peduncolato, ma con nodo a superficie dorsale larga e piatta. Postpeziolo circa tre volte piu largo del peziolo e di poco pill stretto del primo segmento del gastro. Tegumento lucidissimo e liscio su tutta la superficie, interrotto solo da alcune minute fossette piligere sul dorso e molto debolmente zigrinato sui lati del capo, dell'alitronco e del peduncolo. Pochi peli troncati o debolmente claviformi irregolarmente sparsi su tutta la superficie corporea. Colore uniformemente giallo testaceo, leggermente piu offuscato all'apice del gastro e sulle pleure; an cora pill chiaro sulle spine propodeali e sulle appendici.

Lunghezza totale 1,8-2,0 mm.

Dimensioni in mm ed indici: Lc 0,55-0,56; lc 0,47; Lsc 0,47-0,49; Lp 0,34; ap 0,29-0,30; lp 0,16-0,18; Lpp 0,21-0,23; lpp 0,34-0,35; IC 83,72-85,71; ISC 94,74-100,00; IAP 84,62-88,46; IP 46,15-53,85; IPP 144,44-168,75; IPA 75,00-77,78.

Queen
(dealated). Length: 3.3 mm.

Differing from the worker in the following characters: The head is subcircular, not longer than broad, with more convex sides. The epinotal spines are shorter and stouter and not curved, the upper surface of the mesonotum is flattened and the gaster is large and elongate elliptical, the postpetiole even broader in proportion to its length. The wing insertions, a spot on the scutellum, a broad band across the first gastric segment and a much narrower band near the posterior border of each of the following segments are brown.

Prebus (2021) - (n = 1): SL = 0.536; FRS = 0.248; CW = 0.723; CWb = 0.647; PoOC = 0.249; CL = 0.675; EL = 0.219; EW = 0.179; MD = 0.148; WL = 1.114; SPST = 0.253; MPST = 0.245; PEL = 0.363; NOL = 0.216; NOH = 0.137; PEH = 0.274; PPL = 0.208; PPH = 0.321; PW = 0.704; SBPA = 0.334; SPTI = 0.328; PEW = 0.212; PNW = 0.206; PPW = 0.514; HFL = 0.594; HFWmax = 0.146; HFWmin = 0.058; CS = 0.985; ES = 0.309; SI = 83; OI = 31; CI = 96; WLI = 172; SBI = 52; PSI = 23; PWI = 242; PLI = 175; NI = 158; PNWI = 97; NLI = 60; FI = 252.

In full-face view, head subquadrate, slightly broader than long (CI 96). Mandibles weakly striate, shining, and armed with five small teeth, with the apical-most well developed. 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 antennal scape (SI 83). Antennae 12-segmented; antennal club of three segments, with the apical-most segment slightly 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, forming a continuous arc from the posterior of the head, but narrowing as they join the mandibular insertions. Posterior head margin very slightly convex, rounding evenly into the lateral margins.

In profile view, compound eyes ovular and large (OI 31), with 18 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, and evenly rounded posteriorly; not overhanging the metanotum. 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 half as long as the propodeal declivity, tapering evenly from the base, directed posteriorly, very slightly downcurved, and acute. Propodeal declivity straight and flat, forming a rounded ~90° angle with the base of the propodeal spines. Propodeal lobes rounded and weakly developed. Petiole moderately long (PLI 175), without tubercles anterodorsally where it articulates with the mesosoma. Subpetiolar process in the form of a small, very acute tooth; ventral margin of petiole weakly concave posterior to it. Petiolar peduncle short: petiolar node covering most of the petiolar dorsum. Petiolar node robust and subquadrate: transition between peduncle and node evenly rounded, resulting in a very slightly concave anterior node face; anterior face of node forming a sharp ~90° angle with the dorsal face; dorsal face nearly flat, forming a rounded ~90° angle with the posterior face; posterior face forms a ~90° angle with the caudal cylinder. Postpetiole evenly rounded anterodorsally, flattened dorsally, ventral surface weakly lobed.

In dorsal view, mesoscutum covering pronotum anteriorly, but humeri visible laterally as rounded sclerites. Propodeal spines weakly diverging medially, their apices separated from each other by about one and a half times their length. Petiolar peduncle with spiracles very slightly protruding past the lateral margins. Petiolar node trapezoidal and widest anteriorly, and weakly emarginated anterodorsally; node slightly broader than the peduncle, and evenly grading into the caudal cylinder, which is slightly narrower than the node. Postpetiole very broad (PWI 242), somewhat anteroposteriorly compressed, 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 broadly concave, with corners evenly rounding into the lateral margins, which evenly diverge to the angulate posterior corners; posterior margin broadly concave. Metafemur moderately incrassate (FI 252).

Sculpture: median clypeal carina present, extending posteriorly from the anterior clypeal margin to the level of the antennal toruli; flanked by two equally strong carinae. Lateral clypeal lobes with additional weaker carinae; ground sculpture smooth and shining. Antennal scapes shining through very weak, indistinct areolate ground sculpture. Cephalic dorsum predominantly shining, but with weak costulae surrounding the frontal carinae, and rugose sculpture surrounding the compound eye, extending to the mandibular insertions. Pronotal neck areolate. Pronotum smooth and shining with traces of weak areolate sculpture. Katepisternum smooth and shining; anepisternum mostly smooth and shining, but with dense areolate sculpture dorsally. Propodeum with dense areolate sculpture laterally, with superimposed rugae that continue onto the ventro-posterior surface; otherwise the propodeum smooth and shining. Mesoscutum predominantly smooth and shining, but with weak costulae posteromedially. Mesoscutellum smooth and shining. Femora smooth and shining, with traces weak areolate sculpture. Peduncle of petiole smooth and shining anteroventrally. Lateral surfaces of petiole with areolate-rugulose sculpture; dorsal surface entirely smooth and shining. Dorsal surface of postpetiole smooth and shining, with weak areolate sculpture on the posterior quarter, and on the lateral surfaces. Gaster smooth and shining, with very weak 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, 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 lightly colored integument.

Color: entirely light yellow, except for the slightly infuscated posteromedial portion of the mesoscutellum, posterior two thirds of the first gastral tergite, and masticatory margin of the mandible.

Baroni Urbani (1978) - Capo tondeggiante ad angoli occipitali ridotti. Bordo anteriore del clipeo intero, appena leggermente inciso nel mezzo. Mandibole armate di sette denti minuti. Area frontale impressa. Antenne a scapo corto e tozzo: ripiegato all'indietro esso oltrepassa appena il bordo dell'occipite. Superficie dorsale del capo molto bombata ed a diametro massimo all'altezza degli occhi. Alitronco a declivita protoracica molto marcata e verticale. Superficie dorsale piatta. Spine propodeali robuste: piu corte della loro distanza tra gli apici e debolmente divergenti. Peziolo breve mente peduncolato, con nodo subquadrato, a faccia posteriore piana passante con uno spigolo netto in quella anteriore. Postpeziolo largo e campaniforme, articolato su tutta la sua larghezza al primo segmento del gastro che e poco piu largo. Gastro ad angoli anteriori marcati. Brevi peli troncati o debolmente claviformi sparsi su tutto il corpo. Sul gastro tali peli sono frammisti ad altri piu sottili, particolarmente nella meta distale ed al bordo posteriore di ciascun somite. Tegumento liscio interrotto solo da rari punti piligeri, piuttosto opaco sul capo e sull'alitronco, piu lucido sul peduncolo e sul gastro. Deboli tracce di scultura longitudinale sulle mandibole e sui lati del capo.

Lunghezza tot ale 3,8 mm.

Dimensioni in mm ed indici: Lc 0,70; lc 0,68; Lsc 0,52; Lp 0,39; ap 0,26; lp 0,18; Lpp 0,25; lpp 0,49; IC 96,30; ISC 130,00; IAP 50,00; IP 46,67; IPP 200,00; IPA 36,84.

Type Material
Described from three workers and a female taken from a single nest in the ground under a stone at Manneville.

Prebus (2021) - Macromischa flavidula syntype workers and gyne. Manneville, Haiti. One syntype worker here designated lectotype.

Lectotype worker: HAITI: Ouest: Manneville, [no collection date], W.M. Mann, M.C.Z. Cotype 2-4 21015 (MCZENT00021015, top specimen, closest to pin).

Paralectotype workers and gyne: same pin as lectotype: 1 worker & 1 dealate gyne (MCZENT00021015, top specimen furthest from pin and bottom, respectively) [MCZC]; same data as lectotype: 1 worker (CASENT0758362) 2 workers (CASENT0758361).

Baroni Urbani (1978) - HAITI: Manneville, senza ulteriori dati, 9, 1, W.M. Mann leg. (sintipi, 3, 1 No.21015; 6 ).

Etymology
Prebus (2021) - Morphological, from the Latin flavidulus (= yellowish), in reference to the predominantly yellow integument 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.
 * Kempf, W.W. 1972. Catalago abreviado das formigas da regiao Neotropical (Hym. Formicidae) Studia Entomologica 15(1-4).
 * Perez-Gelabert D. E. 2008. Arthropods of Hispaniola (Dominican Republic and Haiti): A checklist and bibliography. Zootaxa 1831:1-530.
 * 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.
 * Wheeler W. M., and W. M. Mann. 1914. The ants of Haiti. Bulletin of the American Museum of Natural History 33: 1-61.