Strumigenys royi Sosa-Calvo, Schultz

Jeffrey Sosa-Calvo, Ted R. Schultz & John S. Lapolla, 2010, A Review of the Dacetine Ants of Guyana (Formicidae: Myrmicinae), Journal of Hymenoptera Research 19, No. 1, pp. 11-43 : 21-26

Strumigenys royi Sosa-Calvo, Schultz , and LaPolla, n. sp.

( Figs 14–25 )

Material examined.— Holotype: worker, labeled ‘‘ GUYANA: Kanuku Mts.: Nappi Creek. camp ; 128 m; 59 ° 33.963 ' W, 3 ° 21.018 ' N; 24.x.2002; J.S. LaPolla; forest; on tree trunk. (JSL021024-08) ’’ USNM ENT No. 00537288 . (UGBC). Paratype: 1 worker, same locality as in holotype. USNM ENT No. 00537289 . (USNM) .

Diagnosis (worker). — Leading edge of antennal scape with all hairs curving to apex, lacking hairs that curve to the base of segment; mandibles long and linear with a small, but conspicuous preapical tooth close to the apicodorsal teeth; propodeum with small denticles; segments of the waist with ventral margin lacking spongiform tissue of any kind; first gastral sternite lacking spongiform pad; body strongly reticulate and with area within each reticulation verrucose; coloration distinctive: mandibles mostly whitish, antennae and legs yellowish, mesosoma mostly ferruginous, waist segments light brown, and head and gaster mostly dark brown or black.

Description (worker). —Head: in full-face view, mandibles thick throughout most of their length and abruptly narrowing just before apex by sudden oblique divergence of inner margin, a minute but conspicuous preapical denticle arising on this oblique section; mandibles with intercalary denticle that arises from dorsal base of apicoventral tooth; in full-face view, anterior margin of clypeus transverse to very slightly concave and with at least 6 narrowly spatulate elongate hairs; dorsum of clypeus finely reticulate-punctate and with short, appressed, simple hairs; ocular carina short, ending at eye level; leading edge of scapes with all hairs curved or inclined toward apex of scape; funicular segments II and III long [holotype: 2 nd = 0.073, 3 rd = 0.092; paratype: 2 nd = 0.079, 3 rd = 0.092], their lengths, when combined, almost as long as funicular segment IV; occipital margin deeply emarginate, forming prominent rounded cephalic lobes; dorsum of head with two pairs of erect fine hairs: one pair close to margin of occipital concavity and another close to highest point of vertex, clearly differing from appressed simple ground-pilosity (sensu Bolton 2000:998: referring to ‘‘the short pilosity often present on cephalic dorsum, dorsolateral margins of head, promesonotum and its margins. These hairs could be simple or spatulate to orbicular, usually decumbent to appressed and may rarely be elevated’’); eye with 13– 14 ommatidia on longest row; apicoscrobal hair elongate and simple (this hair lacking on holotype due to damage); dorsum of head strongly reticulate and with areas within each reticulation verrucose (i.e., containing wart-like protuberances). Mesosoma: humeral hair elongate and simple, similar in shape to apicoscrobal hair but longer; pilosity on dorsum of pronotum consisting of decumbent hairs; dorsum of pronotum with irregular rugae and markedly reticulate with areas within reticulation verrucose; mesonotum, in lateral view, raised and separated from pronotum by transverse or rounded carina; mesonotum, in lateral view, with pair of erect elongate simple hairs and pair of short erect simple hairs; dorsum of mesonotum with conspicuous longitudinal rugae and strongly reticulate with area within reticulation verrucose; mesopleuron and metapleuron separated by deep scrobiculate constriction that extends to dorsum of alitrunk to form metanotal groove; in lateral view, constriction extends backward from propodeum throughout base of propodeal denticles, before beginning of propodeal declivity; propodeum with small denticles; declivity of propodeum with thin reticulate carina; mesopleuron mostly reticulate and with area within reticulation verrucose; proximal to border with metapleuron (and especially upper portion of katepisternum), reticulations fading leaving only verrucose sculpture visible; anepisternum mostly verrucose; metapleuron reticulate and with areas within reticulation verrucose. Metasoma: waist segments lacking ventral spongiform tissue; petiole with anterior acute process; node of petiole, in lateral view, rounded; pilosity on petiole, in frontodorsal view, consisting of anterior pair of elongate, simple suberect hairs and posterior transverse row of four elongate, simple suberect hairs (hair on each side of petiole and pair on posterior dorsum of petiole); posterior margin of petiolar node with low spongiform crest; disc of petiole, in dorsal view, rugose-reticulate and with area within reticulation verrucose. Postpetiole, in lateral view, globose and in fronto-dorsal view, with two transverse rows of four elongate, simple suberect hairs, located on anterior and posterior portions of postpetiole. (Distribution of these hairs similar to that of posterior row on petiole.) Anterior margin of postpetiole, in dorsal view, concave; postpetiole wider than long [length = 0.205, width = 0.238]; posterior margin of postpetiolar disc with small spongiform crest; disc of postpetiole reticulate with areas within reticulations verrucose. First gastral tergite finely reticulate-substrigulate with some verrucose sculpture confined to basigastral area; dorsum of first gastral tergite with widely spaced elongate erect simple hairs. Similar hairs on gastral sternite but more abundant; first gastral sternite reticulate, differing from sculpture on tergite; basigastral costulae longitudinal, spaced, and very short but conspicuous. Color: anterior portion of head yellowish and gradually increasing in color to ferruginous by level of eyes and dark brown on rest of head. Mandibles mostly whitish with tips ferruginous to dark brown. Mesosoma ferrugineous; petiole and postpetiole light brown; legs and antennae yellowish, slightly lighter in color than waist segments; first gastral tergite black or dark brown, second and third gastral tergites ferrugineous, fourth gastral tergite yellowish; first to third gastral sternites ferrugineous, fourth gastral sternite yellowish.

Measurements: holotype (and paratype): EL = 0.16 (0.14), GL = 0.79 (0.78), HL = 0.86, HW = 0.65, ML = 0.49 (0.52), PL = 0.40 (0.37), PPL = 0.19 (0.20), PW = 0.36 (0.35), SL = 0.57 (0.59), TL = 3.53, WL = 0.79 (0.80). Indexes: CI = 75, MI = 57 (60), PI = 51 (46), SI = 88 (90). (n = 2)

Gyne and male.— Unknown.

Etymology.— This species is named in honor of Roy Snelling to acknowledge his numerous contributions to the taxonomy of ants, bees, and wasps. He will live on through the solid foundation he provided for ant taxonomy and through the thousands of specimens that he left behind for myrmecologists to ponder over for many years to come.

Biology.— Strumigenys royi was collected from an upright, living tree trunk in a small dirt tunnel (likely made by termites) that ran up the side of the tree.

Comments.— This large species is easily distinguished from any other species in the genus Strumigenys (sensu Bolton 2000) by lacking the spongiform tissue on the ventral margin of the waist segments (petiole and postpetiole) and lacking a spongiform pad on the first gastral sternite, by having the apical fork of the mandibles with an intercalary denticle that arises from the dorsal base of apicoventral tooth, by having antennal funicular segments II and III, when combined, almost as long as funicular segment IV (shared with S. fairchildi Brown ), by having a minute denticle close to the apicodorsal tooth (similar in S. lanuginosa Wheeler ), and by having marked body sculpture. Due to this combination of characters it is difficult to place this species in any of the species groups given by Bolton (2000).

Strumigenys royi differs from S. idiogenes Bolton, to which it keys out in Bolton’s (2000) key, as the latter possesses: a larger and conspicuous lobe on ventral margin of postpetiole, a narrow spongiform pad on the base of first gastral sternite, asymmetrical dentition on the mandibles, and a pair of narrow spines on the propodeum.

MODIFIED VERSION OF KEY IN BOLTON (2000)

Strumigenys royi will key out to S. idiogenes in Bolton’s (2000) ‘‘key to Neotropical-Nearctic Strumigenys species. ’’ The key for the species of Strumigenys can be modified as below to include S. royi . Numbering of couplets follows Bolton (2000).

4. Mandibles without intercalary teeth or denticles that arise between apicodorsal and apicoventral teeth of apical fork, nor arise from dorsal base of apicoventral tooth........................................ couplet 5 of Bolton (2000)

– Mandible with 1 or 2 intercalary teeth or denticles that arise between apicodorsal and apicoventral teeth of apical fork, or arise from dorsal base of apicoventral tooth........................................ couplet 10 of Bolton (2000)

10. Mandibles without, or with only one, preapical tooth or denticle couplet 11 of Bolton (2000)

– Mandible with 2 preapical teeth or denticles............ couplet 15 of Bolton (2000)

11. Preapical dentition consisting of single tooth on one or both mandibles; preapical tooth conspicuously dentiform and located close to apicodorsal tooth............. 12

– Preapical dentition absent from both mandibles or single minute denticle present; if the latter denticle located close to midlength, not near apicodorsal tooth...... 14

12. First gastral tergite very densely clothed with long fine flagellate hairs. Dorsolateral margin of head with 2 freely laterally projecting long flagellate hairs, one at level of eye, other apicoscrobal...................................... lanuginosa

– First gastral tergite with stout curved hairs that are remiform or apically spatulate or simple erect standing hairs. Dorsolateral margin of head without projecting flagellate hairs or with single hair, in apicoscrobal position................ 13

13. Scape strongly dorsoventrally flattened and very broad; in full-face view maximum width of scape greater than maximum width of mandible. First gastral tergite unsculptured. Pronotal humeral hairs stiff and stout. With head in profile highest point of vertex without erect hairs............................. platyscapa

– Scape subcylindrical; in full-face view maximum width of scape less than maximum width of mandible. First gastral tergite with sculpture present other than basigastral costulae. Pronotal humeral hairs elongate or flagellate. With head in profile highest point of vertex with pair of erect hairs.................... 13b

13b. Ventral surface of postpetiole with large and distinct spongiform lobe. Propodeal spines long. Mandibles with asymmetrical preapical dentition (left mandible without trace of preapical dentition, right mandible with small slender preapical tooth located close to apicodorsal tooth and slightly smaller than intercalary tooth).................................................... idiogenes

– Ventral surface of postpetiole without spongiform lobe or crest. Propodeal spines short. Mandibles with symmetrical preapical dentition (both mandibles with small preapical tooth located close to apocidorsal tooth)............ royi new species

Figures

Figs 14–22. Scanning electron micrographs of the holotype worker of Strumigenys royi, new species. 14, Lateral view. 15, Lateral view of head. 16, Full-face view. 17, Closed mandibles. 18, Lateral view of mesosoma. 19, Lateral view of petiole, postpetiole, and gaster. 20, Dorsal view of mesosoma. 21, Dorsal view of mesosoma, waist segments, and first gastral tergite. 22, Dorsal view of waist segments (petiole and postpetiole).

Figs 23–25. Automontage images of a paratype of Strumigenys royi, new species. 23, Full-face view. 24, Dorsal view. 25, Lateral view.