Temnothorax flavidulus ( Wheeler & Mann, 1914 )

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 : 294-299

Temnothorax flavidulus ( Wheeler & Mann, 1914)

Distribution: Fig. 133F ; worker & gyne: Fig. 140 .

Macromischa flavidula Wheeler & Mann, 1914: 37 fig. 15. Syntype workers and gyne. Manneville , Haiti. One syntype worker here designated lectotype.

Macromischa (Antillaemyrmex) flavidula (Wheeler & Mann) : Mann, 1920: 408. First combination in Macromischa (Antillaemyrmex) .

Antillaemyrmex flavidulus (Wheeler & Mann) : Wheeler, 1931: 32. First combination in Antillaemyrmex .

Leptothorax flavidulus (Wheeler & Mann) : Baroni Urbani, 1978: 441. First combination in Leptothorax .

Temnothorax flavidulus (Wheeler & Mann) : Bolton, 2003: 271. First combination in Temnothorax .

Type material examined: Lectotype worker of Macromischa flavidula : 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 of Macromischa flavidula : 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) [ USNM] 2 workers (CASENT0758361) [ USNM] .

Geographic range: Low elevations of Hispaniola ( Fig. 133F ).

Worker diagnosis: 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 sp. nov., T. ciferrii , T. harlequina sp. nov., T. hippolytus sp. nov., T. magnabulla sp. nov., T. pulchellus and T. terricola . The erect setae count of four on the dorsum of the petiolar node differentiates T. flavidulus from T. terricola and T. hippolytus sp. nov., 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 sp. nov., in which the mesosoma is flatter and the petiolar node transition is evenly rounded. Temnothorax flavidulus and T. harlequina sp. nov. can be separated most easily by the color of the integument: T. harlequina sp. nov. 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 sp. nov. 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 sp. nov. they are nearly the same width. Temnothorax flavidulus may also be confused with T. agavicola sp. nov., but the head sculpture of this species is areolate, in contrast the smooth and shining sculpture of T. flavidulus .

Worker measurements & indices (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).

Worker description: 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.

Gyne measurements & indices (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.

Gyne description: 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.

Male: Unknown.

Etymology: Morphological, from the Latin flavidulus (= yellowish), in reference to the predominantly yellow integument of this species.

Comments: 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 . 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 flavidulus from ciferrii , with 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. Temnothorax flavidulus is part of a large complex of species endemic to the island of Hispaniola and its smaller outlying islands, including T. bahoruco sp. nov., T. balaclava sp. nov., T. ciferrii , T. harlequina sp. nov., T. wilsoni sp. nov., and 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.

Figures

Figure 133 Geographical and elevational distribution of the pulchellus group. (A) Temnothorax agavicola sp. nov. (B) T. albispinus. (C) T. bahoruco sp. nov. (D) T. balaclava sp. nov. (E) T. ciferrii (F) T. flavidulus (G) T. harlequina sp. nov. (H) T. hippolytus sp. nov. (I) T. laticrus sp. nov. (J) T. magnabulla sp. nov. (K) T. pulchellus (L) T. terricola (M) T. torrei (N) T. wettereri sp. nov. (O) T. wilsoni 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; if present, types of synonyms are named; 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-133

Figure 140 Temnothorax flavidulus. (A–C) Lectotype worker (MCZENT00021015). (A) Full-face view. (B) Profile view. (C) Dorsal view. (D–F) Paralectotype gyne (MCZENT00021015). (D) Full-face view. (E) Profile view. (F) Dorsal view. Scale bars 0.2 mm. Full-size DOI: 10.7717/peerj.11514/fig-140