Temnothorax caryaluteus, Prebus & Nguyen & Doering & Booher, 2024

Prebus, Matthew M., Nguyen, Nhi, Doering, Grant Navid & Booher, Douglas B., 2024, Temnothorax caryaluteus sp. nov. (Hymenoptera: Formicidae): a new ant species from the eastern United States, European Journal of Taxonomy 970, pp. 175-202 : 181-189

Temnothorax caryaluteus sp. nov.

urn:lsid:zoobank.org:act:71800550-6BD3-475F-B7BC-D5C0BBF15686

Fig. 4

Diagnosis

Among the species of the eastern United States, the worker of Temnothorax caryaluteus sp. nov. is distinguishable by the following combination of characters: antennae 11-segmented; antennal scrobe absent; mandible with five masticatory teeth; antennal scape long: when fully retracted, failing to reach the posterior margin of the head by <2 times the width of the antennal scape; subpetiolar process absent or weakly developed; propodeal spines shorter than, or as long as, the propodeal declivity in profile view, varying from as long as broad to twice as long as broad at the base; dorsum of mesosoma sculptured; workers> 3 mm in length; head, mesosoma, and gaster integument light colored (often yellowish-orange), with the posterior half of the first gastral tergite infuscated; propodeal spines closely approximated, their bases separated by roughly the length of the propodeal spine in dorsal view, their union forming a U-shape; apex of petiolar node acute to narrowly rounded in profile view, about as half as wide as the petiole in dorsal view; mesosoma slightly arched in profile view. Free-living (nonparasitic) species; nests under bark and in dead branches and twigs of live trees.

Etymology

The name caryaluteus is a portmanteau of ancient Greek carya (“walnut”, the genus name for hickory) and the Latin luteus (“yellow”). This name was proposed by Brodie Gaudie as the result of an outreach project conducted by the authors in coordination with the United States Forest Service, in which several elementary school classes partook in a workshop focused on the practice of taxonomy and its underlying philosophy. Names for the new species were proposed by classrooms and individuals and were subsequently voted on in a social media campaign.

Type material examined

Holotype USA – Kentucky • ☿; Whitley County, Williamsburg ; 36.739° N, 84.168° W ± minute; 320 m a.s.l.; 27 Jul. 2015; M. Deyrup #ANTC43885; in fallen branch of Carya illinoiensis ; USNM, CASENT4011115 .

Paratypes USA – Kentucky • 1 dealate ♀; same data as for holotype; USNM, CASENT4011128 • 3 ☿☿; same data as for holotype; USNM, CASENT4011123 to CASENT4011125 • 3 ☿☿; same data as for holotype; USNM, CASENT4011141 to CASENT4011143 • 2 ☿☿; same data as for holotype; ABS, CASENT0759059 to CASENT0759060 • 2 ☿☿; same data as for holotype; ASUHIC, CASENT4011121 to CASENT4011122 • 2 ☿☿; same data as for holotype; CASC, CASENT0759057 to CASENT0759058 • 6 ☿☿; same data as for holotype; MCZC, CASENT4011106 to CASENT4011111 • 2 ☿☿; same data as for holotype; MEM, CASENT0759052 to CASENT0759053 • 3 ☿☿; same data as for holotype; UGCA, CASENT4011112 to CASENT4011114 • 5 ☿☿; same data as for holotype; UGCA, CASENT4011116 to CASENT4011120 • 2 ☿☿; same data as for holotype; UTIC, CASENT0759054 to CASENT0759055 • 2 ☿☿; same data as for holotype; VMNH, CASENT4011104 to CASENT4011105 .

Non-type material examined

USA – Alabama • 1 dealate ♀; Madison County, 2.3 miles SE of Gurley ; 34.0158° N, 86.33611° W; 295 m a.s.l.; 10 Jun. 2018; S.Y. Wang #ANTC46095; by pasture; UV-light/sheet; MEM, MEM238160 . – Arkansas • 1 ☿; Newton County, Buffalo National River , Steel Creek ; 36.038853° N, 93.33729° W; 300 m a.s.l.; 9 Oct. 2009; M. Skvarla and R. Fisher #ANTC46096; MEM, MEM241251 . – Georgia • 1 ☿; Clarke County, Sandy Creek Nature Center ; 33.98683° N, 83.38283° W ± minute; 205 m a.s.l.; 30 Apr. 2012; D. Booher #DBB234W; UGCA, CASENT0750495 • 2 ☿☿; Whitfield County, near Pinhoti trail crossing on access road; 34.739° N, 85.0167° W ± 50 m; 432 m a.s.l.; 30 Mar. 2012; D. Booher #DBBC5000; hardwood forest, chestnut oak: fork of dead branch on live tree; UGCA, CASENT0749972 to CASENT0749973 • 3 ☿☿; same data as for preceding; D. Booher #DBBC5000b; UGCA, CASENT0749974 to CASENT0749976 • 6 ☿☿; same data as for preceding; UGCA, CASENT0749978 to CASENT0749983 . – Indiana • 1 dealate ♀; Dubois County, Jasper ; 38.391442° N, 86.931109° W ± 5 km; 150 m a.s.l.; 28 Feb. 2021; J. Ruhe #ANTC46158; lab colony, reared from queen collected at blacklight; MMPC, CASENT4010186 • 1 ☿; same data as for preceding; MMPC, CASENT4010185 • 1 ☿; same data as for preceding; 18 Mar. 2021; J. Ruhe #ANTC46159; MMPC, CASENT4010187 • 2 ♂♂; Monroe County, Bloomington, Griffey Lake Nature Preserve ; 39.205833° N, 86.525278° W; 230 m a.s.l.; 10 Jun. 2024; G. Doering #GLTca1; oak-hickory forest, under bark of downed tree; MMPC, CASENT4012894 , CASENT4012904 • 2 ☿☿; same data as for preceding; MMPC, CASENT4012895 , CASENT4012897 • 1 ♂; same data as for preceding; USNM, CASENT4012896 • 1 ♂; same data as for preceding; ABS, CASENT4012898 • 1 ♂; same data as for preceding; UGCA, CASENT4012899 • 1 ♂; same data as for preceding; ASUHIC, CASENT4012900 • 1 ♂; same data as for preceding; CASC, CASENT4012901 • 1 ♂; same data as for preceding; MCZC, CASENT4012902 • 1 ♂; same data as for preceding; MEM, CASENT4012903 . – Kentucky • 1 ☿; Whitley County, Williamsburg ; 36.743418° N, 84.159654° W ± minute; 300 m a.s.l.; 25 Jun. 2017; M. Deyrup #ANTC43836; emerged from dead branch Carya illinoiensis ; ABS, CASENT0758863 • 2 ☿☿; same data as for preceding; ABS, CASENT4011101 to CASENT4011102 • 1 ♀; same data as for preceding; ABS, CASENT4011100 • 1 ♀; same data as for preceding; ABS, CASENT4011103 • 1 ☿; same data as for preceding; 36.739° N, 84.168° W ± minute; 320 m a.s.l.; 27 Jul. 2015; M. Deyrup #ANTC43883; branch of Carya illinoiensis ; ABS, CASENT0759047 • 4 ☿☿; same data as for preceding; 16 Mar. 2015; M. Deyrup #ANTC43884; in dead branch of Carya illinoiensis ; ABS, CASENT0759048 to CASENT0759051 • 9 ☿☿; same data as for preceding; ABS, CASENT4011129 to CASENT4011137 • 23 ☿☿; same data as for preceding; 27 Jul. 2015; M. Deyrup #ANTC43887; branch of Carya illinoiensis ; ABS, CASENT0759061-5 , CASENT4011138-55 . – Mississippi • 1 ☿; DeSoto County, 1 mile north of Handy Corner ; 34.978889° N, 89.742222° W; 120 m a.s.l.; 18 Aug. 2005; A.B. Edwards #ANTC46097; Lindgren funnel trap baited with Typosan and alpha-pinene; MEM, MEM 241880 • 1 ☿; Lee County, Natchez Trace , mile 273; 34.406111° N, 88.6375° W; 125 m a.s.l.; 27 May 2003; T.L. Schiefer and J.A. MacGown #ANTC46098; deciduous forest, Lindgren funnel trap; MEM, MEM 241875 • 1 ☿; Madison County, Natchez Trace Parkway ; 32.654167° N, 89.778056° W; 115 m a.s.l.; 10 Jul. 2002; M. Allred and K. Lewis #ANTC46099; Lindgren funnel trap; MEM, MEM 241881 • 1 ☿; Marshall County, Wall Doxey State Park ; 34.661389° N, 89.465556° W; 110 m a.s.l.; 15 May 2006; A.B. Edwards #ANTC46100; Lindgren funnel trap baited with Typosan; MEM, MEM 241878 . – Missouri • 1 ☿; Barry County, Roaring River State Park ; 36.58559° N, 93.836411° W ± 1 km; 315 m a.s.l.; 27 Jun. 1995; A.L. Wild #ANTC46161; man-modified “lawn” near parking lot; UTIC, UTIC219525 • 1 ☿; same data as for preceding; UTIC, UTIC204575 . – Virginia • 1 ☿; Shenandoah County, near Elizabeth Furnace Campground ; 38.94978102° N, 78.299409° W ± 3 m; 210 m a.s.l.; 24 May 2015; M.M. Prebus #MMP1896; riparian mixed hardwood forest, nest in dead standing wood; MMPC, CASENT0755055 • 1 ☿; same data as for preceding; M.M. Prebus #MMP1897; MMPC, CASENT0755056 • 1 ☿; same data as for preceding; 38.94893202° N, 78.29862496° W ± 3 m; 215 m a.s.l.; 24 May 2015; M.M. Prebus #MMP1899; riparian mixed hardwood forest, single worker in dead branch on live tree; MMPC, CASENT0755063 .

Description

Worker

Measurements and indices (n = 38): SL = 0.345 –0.476 (0.428); FRS = 0.153–0.25 (0.205); CW = 0.484 – 0.616 (0.572); CWb = 0.442 –0.586 (0.532); PoOC = 0.201 –0.267 (0.240); CL = 0.515 –0.642 (0.598); EL = 0.104 –0.156 (0.133); EW = 0.079 –0.113 (0.097); MD = 0.104 –0.186 (0.142); WL = 0.567 –0.757 (0.690); SPST = 0.115 –0.181 (0.153); MPST = 0.17–0.241 (0.212); PEL = 0.217 –0.288 (0.263); NOL = 0.11–0.172 (0.146); NOH = 0.039–0.11 (0.086); PEH = 0.149 –0.216 (0.191); PPL = 0.129 –0.202 (0.163); PPH = 0.134 –0.185 (0.164); PW = 0.288 –0.387 (0.349); SBPA = 0.067–0.13 (0.101); SPTI = 0.103 –0.174 (0.152); PEW = 0.123 –0.166 (0.140); PNW = 0.052 –0.085 (0.070); PPW = 0.156 –0.214 (0.194); HFL = 0.361 –0.514 (0.460); HFWmax = 0.093 –0.132 (0.118); HFWmin = 0.037 –0.056 (0.046); CS = 0.489 –0.612 (0.565); ES = 0.093 –0.132 (0.115); SI = 73.7–89 (80.6); EI = 21.5–28.5 (24.9); CI = 82.6–100.2 (88.9); WLI = 120–142 (130); SBI = 14.3–22.7 (19.0); PSI = 18.6–26.1 (22.3); PWI = 122–152 (138); PLI = 123–192 (163); NI = 138–290 (177); PNWI = 41.6–58.6 (49.9); NLI = 42.6–64.2 (55.7); FI = 222–300 (258); FRSI = 30.8–46.7 (38.6); SPTII = 21.9–31.8 (28.5).

In full face view, head subquadrate, often longer than broad (CI 82.6–100.2). Mandibles weakly, finely 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 margin convex. Antennal scapes short: when fully retracted, failing to reach the posterior margin of the head capsule by about the two times the maximum width of the scape (SI 73.7–89). Antennae 11-segmented; antennal club of composed of three segments, with the apical-most segment about the same length as the preceding two in combination. Frontal carinae short, extending past the antennal toruli by about two times the maximum width of the antennal scape. Compound eyes weakly protruding past the lateral margins of the head capsule. Lateral margin of head very weakly convex above the compound eyes to the posterior margin of the head, slightly constricted below the compound eyes to the mandibular insertions. Posterior head margin weakly concave medially, rounding evenly into the lateral margins.

In profile view, compound eyes elongate-ovular and small (EI 21.5–28.5), with 10 ommatidia in longest row. Pronotal declivity indistinct, neck and anterior face of pronotum forming a ~120° angle. Mesosoma arched: evenly convex from where it joins the pronotal neck to propodeal spines. Promesonotal suture extending from the posterior margin of the procoxal insertion to the mesothoracic spiracle, which is moderately well developed, then continuing dorsally as a weak disruption of the integument sculpture. Metanotal groove visible as a weak disruption of the sculpture laterally from where it arises between the mid- and hind coxae to the poorly developed metathoracic spiracle, which is nearly indistinguishable against the ground sculpture, then continuing dorsally as a weak disruption of the integument sculpture. Propodeal spiracle weakly developed, directed posterolaterally, and separated from the propodeal declivity by about three spiracle diameters. Propodeal spines short (PSI 18.6–26.1), about two thirds the length of the propodeal declivity, tapering evenly from the base, slightly curved, and acute. Propodeal declivity weakly concave, forming a rounded ~100° angle with the base of the propodeal spines. Propodeal lobes rounded and weakly developed. Metapleural gland bulla small, extending from the metacoxal insertion halfway to the propodeal spiracle. Petiole short (PLI 123–192), with tubercles anterodorsally. Subpetiolar process in the form of a small, acute, triangular tooth which grades evenly into the ventral margin of the petiole posteriorly; ventral margin of petiole flat to weakly concave posterior to it. Petiolar peduncle short: comprising less than a quarter of the total petiole length. Petiolar node erect and cuneiform to slightly rounded: peduncle grading evenly into the anterior node face; anterior face forming a ~90° angle with the flat posterior face; posterior face forms a ~120° angle with the caudal cylinder. Postpetiole rounded anteriorly, anterior face rounds evenly into the dorsal face; 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. Promesonotal groove visible as a disruption in the ground sculpture. Metanotal groove visible as a disruption in the ground sculpture. Propodeal spines closely approximated basally and diverging apically, their apices separated from each other by about twice their length, the negative space between them “V”-shaped. Petiolar peduncle with spiracles weakly protruding past the lateral margins. Petiolar node, when viewed at a posterodorsal aspect, tapering evenly from the base, with the dorsal margin evenly convex; apex of node narrower than the peduncle and caudal cylinder. Postpetiole narrow (PWI 122–152) and campaniform. Anterior margin of the postpetiole evenly rounds into the lateral margins; lateral margins parallel to the rounded posterior corners; posterior margin notched. Metafemur weakly to moderately incrassate (FI 222–300).

Sculpture: median clypeal carina absent, remainder with longitudinal rugulae. Lateral clypeal lobes with additional rugulae; ground sculpture smooth. Antennal scapes weakly sculptured. Cephalic dorsum predominantly areolate, with the slightly longitudinally elongate areolae arranged into longitudinal rows by fine costulae; very fine concentric rugulae surrounding the antennal insertions. Lateral surfaces of head sculptured similarly to the dorsum, becoming smooth behind the compound eyes; fine rugose sculpture overlying the areolate sculpture between the compound eye and mandibular insertion. Ventral surface of head mostly smooth and shining. Pronotal neck and anterior face of the pronotum areolate. Lateral surface of the pronotum longitudinally rugose. Meso- and metapleurae areolate, with fine costulae overlying the ground sculpture. Smooth and shining with weak areolae between the propodeal spiracle and the propodeal spines. Dorsal surface of pronotum longitudinally rugose, becoming anastomosed anteriorly. Dorsal face of the mesonotum smooth and shining. Dorsal face of propodeum rugose. Femora shining. Petiole predominantly areolate; anterior face of petiolar node smooth and shining. Postpetiole predominantly areolate; anterior face smooth and shining. First gastral tergite and 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 moderately abundant, erect, blunt-tipped setae, the longest of which are about the width of the compound eye. The head bears ~28, mesosoma ~14, petiole 4, postpetiole ~6, and first gastral tergite ~26 setae.

Color: predominantly orange-yellow, with the posterior margin of the first gastral tergite slightly infuscated.

Gyne

Measurements and indices (n = 4): SL = 0.429 –0.455 (0.440); FRS = 0.219 –0.237 (0.228); CW = 0.655 – 0.688 (0.671); CWb = 0.597 –0.654 (0.618); PoOC = 0.231 –0.247 (0.239); CL = 0.622 –0.677 (0.643); EL = 0.221 –0.231 (0.226); EW = 0.175 –0.189 (0.182); MD = 0.102 –0.116 (0.108); WL = 1.014 –1.051 (1.029); SPST = 0.136 –0.164 (0.149); MPST = 0.243 –0.276 (0.260); PEL = 0.329 –0.358 (0.344); NOL = 0.179–0.18 (0.180); NOH = 0.13–0.137 (0.134); PEH = 0.238 –0.256 (0.247); PPL = 0.179 –0.194 (0.189); PPH = 0.212 –0.237 (0.226); PW = 0.576 –0.595 (0.585); SBPA = 0.245–0.26 (0.253); SPTI = 0.205 –0.211 (0.208); PEW = 0.191 –0.195 (0.194); PNW = 0.1–0.114 (0.104); PPW = 0.25–0.274 (0.260); HFL = 0.531 –0.562 (0.545); HFWmax = 0.127 –0.136 (0.131); HFWmin = 0.048 –0.058 (0.051); CS = 0.616 –0.666 (0.631); ES = 0.198 –0.210 (0.204); SI = 69.6–73.2 (71.2); EI = 35.3–37.0 (36.5); CI = 93.4–100.0 (96.1); WLI = 161–173 (167); SBI = 39.8–41.9 (40.9); PSI = 13.2–15.6 (14.4); PWI = 128–141 (134.199); PLI = 176–185 (182); NI = 131–138 (134); PNWI = 51.3–58.8 (53.8); NLI = 50.3–54.4 (52.2); FI = 234–271 (258); FRSI = 36.2–37.7 (36.9); SPTII = 32.0–34.5 (33.7).

In full face view, head subquadrate (CI 93.4–100.0). Mandibles weakly 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 evenly convex medially. Frontal carinae moderately long, extending past the antennal toruli by about four times the maximum width of the antennal scape. 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 69.6–73.2). Antennae 11-segmented; antennal club composed of three segments, with the apical-most segment about as long as the preceding two in combination. Compound eyes protruding past the lateral margins of the head capsule. Lateral margins of head evenly convex behind the compound eyes, then parallel to each other from the mandibular insertions to below the compound eyes. Posterior head margin flat, rounding evenly into the lateral margins.

In profile view, compound eyes ovular and large (EI 35.3–37.0), with 15 ommatidia in longest row. Mesoscutum rounded evenly anteriorly, covering the dorsal surface of the pronotum, and flat dorsally. Mesoscutellum slightly lower than the mesoscutum; rounded posteriorly. Posterior margin of metanotum extending past the posterior margin of the mesoscutum. Propodeal spiracle moderately well developed, directed posterolaterally, and separated from the propodeal declivity by about three spiracle diameters. Propodeal spines stout and short (PSI 13.2–15.6), about a quarter as long as the propodeal declivity, tapering evenly from the base and blunt. Propodeal declivity weakly concave, rounding evenly into the base of the propodeal spines. Propodeal lobes rounded and very weakly developed. Metapleural gland bulla large, extending from the metacoxal insertion three quarters of the way to the propodeal spiracle. Petiole moderately long (PLI 176–185), with flanges anterodorsally. Subpetiolar process in the form of a small, acute, triangular tooth, which grades evenly into the ventral margin of the petiole posteriorly. Petiolar peduncle short: comprising about a quarter of the total petiole length. Petiolar node erect and cuneiform: peduncle transitioning evenly into the anterior node face; anterior face forming a blunt ~90° angle with the posterior face; posterior face grading evenly into the caudal cylinder. Postpetiole evenly rounded dorsally; ventral surface weakly lobed.

In dorsal view, mesoscutum covering pronotum anteriorly, but humeri visible laterally as rounded sclerites. Propodeal spines parallel to each other, their apices separated from each other by about three times their length. Petiolar peduncle with spiracles covered by a small carina. Petiolar node, when viewed at a posterodorsal aspect, tapering dorsally; dorsal margin convex. Apex of petiolar node about a third as wide as the base; narrower than the caudal cylinder. Postpetiole narrow (PWI 128–141) and subquadrate. Anterior margin of postpetiole evenly rounding into the lateral margins, which converge slightly to the rounded posterior corners; posterior margin medially notched. Metafemur weakly incrassate (FI 234–271).

Sculpture: median clypeal carina absent, remainder with longitudinal rugulae. Lateral clypeal lobes with additional carinae; ground sculpture smooth. Antennal scapes weakly sculptured. Cephalic dorsum longitudinally rugulose, with ground sculpture weakly areolate. Fine concentric costulae surrounding the antennal insertions. Lateral surfaces of head sculptured similarly to the dorsum, but with rugulae arranged into concentric whorls around the compound eyes; rugulose sculpture between the compound eye and mandibular insertion. Ventral surface of head with weak costulae. Pronotal neck areolate. Anterior face of pronotum areolate. Lateral face of pronotum rugose anteriorly. Katepisternum, and anepisternum weakly areolate, with weak longitudinal costulae. Metapleural gland bulla with costate sculpture overlying it. Lateral face of propodeum strigulate. Propodeal declivity weakly costate. Mesoscutum and mesoscutellum with weak costulae over smooth and shining ground sculpture. Dorsum of propodeum costulate. Femora smooth and shining. Petiole predominantly areolate-rugulose. Postpetiole predominantly areolate-rugulose; anterior face smooth and shining. First gastral tergite and 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 moderately abundant, blunt setae, the longest of which are about a third of the width of the compound eye. Short, sparse pubescence present on the mesosoma.

Color: predominantly orange-yellow, with the wing bases and the posterior margin of the first gastral tergite slightly infuscated.

Male

Measurements and indices (n = 8): SL = 0.154 –0.174 (0.164); FRS = 0.092 –0.125 (0.115); CW = 0.545 –0.568 (0.553); CWb = 0.458 –0.478 (0.466); PoOC = 0.161 –0.182 (0.172); CL = 0.449–0.48 (0.465); EL = 0.227 –0.247 (0.235); EW = 0.195 –0.212 (0.202); MD = 0.036 –0.052 (0.044); WL = 0.973 –1.065 (1.012); SPST = N/A; MPST = 0.197 –0.244 (0.225); PEL = 0.193–0.25 (0.219); NOL = 0.153 –0.182 (0.164); NOH = 0.12–0.145 (0.13); PEH = 0.167–0.19 (0.176); PPL = 0.165 –0.211 (0.186); PPH = 0.172 –0.196 (0.189); PW = 0.473 –0.537 (0.515); SBPA = N/A; SPTI = N/A; PEW = 0.124 –0.151 (0.137); PNW = 0.086 –0.143 (0.119); PPW = 0.192–0.24 (0.212); HFL = 0.632 –0.667 (0.647); HFWmax = 0.073 –0.096 (0.087); HFWmin = 0.036 –0.054 (0.047); CS = 0.456 –0.478 (0.465); ES = 0.212–0.23 (0.219); SI = 33–38 (35.3); EI = 47.9–53.7 (50.5); CI = 98.9–102.9 (100.2); WLI = 212–233 (217); SBI = N/A; PSI = N/A; PWI = 144–166 (154); PLI = 103–136 (118); NI = 109–148 (128); PNWI = 68.7–113.5 (87.1); NLI = 68.6–80.3 (75.1); FI = 154–218 (188); FRSI = 19.9–26.8 (24.7); SPTII = N/A.

In full face view, head globular (CI 98.9–102.9). Mandibles very weakly 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 flat medially. Frontal carinae short, extending past the antennal toruli by about two times the maximum width of the antennal scape. Antennal scapes short: when fully retracted, failing to reach the posterior margin of the head capsule by about four times the maximum width of the scape (SI 33–38). Antennae 12-segmented; antennal club composed of four segments, with the apical-most segment about as long as the preceding two in combination. Compound eyes large and protruding past the lateral margins of the head capsule. Lateral margins of head evenly convex behind the compound eyes, rounding evenly into the posterior margin, then parallel to each other from the mandibular insertions to below the compound eyes. Posterior head margin convex, rounding evenly into the lateral margins.

In profile view, compound eyes ovular and very large (EI 47.9–53.7), with 18 ommatidia in longest row. Mesoscutum rounded evenly anteriorly, covering the dorsal surface of the pronotum, and weakly convex dorsally. Mesoscutellum on the same plain as the mesoscutum; evenly convex. Posterior margin of metanotum extending past the posterior margin of the mesoscutum. Propodeal spiracle moderately well developed, directed posterolaterally, and separated from the propodeal declivity by about three spiracle diameters. Propodeal spines absent, represented by blunt angles. Propodeal declivity weakly concave. Propodeal lobes rounded and very weakly developed. Petiole short (PLI 103–136), with blunt angles anterodorsally. Subpetiolar process in the form of a very small triangular tooth, which grades evenly into the ventral margin of the petiole posteriorly. Petiolar peduncle short: comprising about a one sixth of the total petiole length. Petiolar node low and evenly rounded: peduncle transitioning evenly into the anterior node face; anterior face rounding evenly into the posterior face; posterior face grading evenly into the caudal cylinder. Postpetiole evenly rounded dorsally; ventral surface weakly lobed.

In dorsal view, mesoscutum covering pronotum anteriorly, but humeri visible laterally as rounded sclerites. Petiolar node, when viewed at a posterodorsal aspect, tapering dorsally; dorsal margin convex. Apex of petiolar node about half as wide as the base; narrower than the caudal cylinder. Postpetiole narrow (PWI 144–166) and subquadrate; slightly broader anteriorly. Anterior margin of postpetiole evenly rounding into the lateral margins, which converge slightly to the rounded posterior corners; posterior margin medially notched. Metafemur thin (FI 154–218).

Sculpture: median clypeal carina absent, remainder with faint longitudinal rugulae. Lateral clypeal lobes with weakly rugulose; ground sculpture smooth. Antennal scapes smooth. Cephalic dorsum longitudinally rugulose, with ground sculpture weakly areolate. Lateral surfaces of head sculptured similarly to the dorsum, but with rugulae arranged into concentric whorls around the compound eyes; rugulose sculpture between the compound eye and mandibular insertion. Ventral surface of head weakly rugulose. Pronotal neck weakly areolate. Anterior face of pronotum weakly areolate, mostly smooth. Lateral face of pronotum smooth anteriorly. Katepisternum and anepisternum smooth and shining. Lateral face of propodeum weakly strigulate. Propodeal declivity areolate. Mesoscutum and mesoscutellum smooth and shining. Dorsum of propodeum weakly costulate. Femora smooth and shining. Petiole weakly areolate. Postpetiole predominantly smooth and shining, weakly rugulose on posterior margin. First gastral tergite and 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 moderately abundant, tapering setae, the longest of which are about a third of the width of the compound eye.

Color: predominantly pale yellow, with the head capsule, mesoscutellum, and the posterior margin of the first gastral tergite infuscated.

Distribution and ecology

Temnothorax caryaluteus sp. nov. is broadly distributed throughout the eastern United States, but apparently commonly misidentified as T. ambiguus , most likely due to the short propodeal spines. The geographic range of T. caryaluteus is contained completely within the range of T. curvispinosus , its closest relative (Prebus in prep.), but appears to be confined to slightly lower latitudes (see Fig. 5 ). We were unable to find a range overlap between T. caryaluteus and T. ambiguus , although they come into close contact in Virginia and West Virginia. It is likely that in this region their ranges are stratified by elevation, with T. ambiguus inhabiting mountain tops. All nest collections of T. caryaluteus have been taken from dead wood on live trees. The known host trees are Carya illinoiensis (Wangenh.) K.Koch and Quercus montana Willd. , both of which are common and widespread hardwoods in the eastern United States. All collections have occurred below 500 m.

Notes

Temnothorax caryaluteus sp. nov. will visit blacklights, but we have only a single date associated with an alate collection event: 10 Jun. 2018 in Madison Co., AL by Steven Wang. Like the worker, the gyne of T. caryaluteus may be confused with that of T. ambiguus or T. curvispinosus . In agreement with Wesson & Wesson (1940), we found significant differences in the distributions of Weber’s length (WL) and pronotum width (PW) in gynes (Supp. file 3), but we hesitate to use these as diagnostic characters due to the presence of microgynes in T. curvispinosus in at least some parts of its range (Prebus pers. obs.). Temnothorax caryaluteus exhibits some integument color variation across its range. Most worker specimens that we have examined are predominantly orange-yellow, with the posterior margin of the first gastral tergite slightly infuscated, but one specimen from the vicinity of Athens, GA is predominantly medium brown (CASENT0750495).

All collections of Temnothorax caryaluteus sp. nov. to date have been made from under bark or in dead branches and twigs on live trees in the genera Quercus and Carya . This nesting preference is only shared by one other species of Temnothorax in the eastern United States: T. schaumii . Notably T. curvispinosus , a close relative of T. caryaluteus , is only rarely found under bark on live trees or in galls, and T. ambiguus has never been recorded from arboreal microhabitats ( Table 1 ). Below, we include a reformulated and updated key to the workers of Temnothorax species from the eastern United States.

Figures

Fig. 4. Castes of Temnothorax caryaluteus sp. nov. a–c. Holotype ☿ (USNM, CASENT4011115). a. Full face view. b. Profile view. c. Dorsal view. d–f. Paratype ♀ (USNM, CASENT4011128). d. Full face view. e. Profile view. f. Dorsal view. g–i. Non-type ♂ (USNM, CASENT4012896). g. Full face view. h. Profile view. i. Dorsal view. Scale bars 0.2 mm.

Fig. 5. Distribution map comparing the ranges of Temnothorax caryaluteus sp. nov., T. ambiguus (Emery, 1895), and T. curvispinosus (Mayr, 1866) in North America.