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December 1986

STINGS OF ANTS OF THE TRIBE PHEIDOLOGETINI (MYRMICINAE)

Charles Kugler Radford University, Radford, VA

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Kugler, Charles, "STINGS OF ANTS OF THE TRIBE PHEIDOLOGETINI (MYRMICINAE)" (1986). Insecta Mundi. 514. https://digitalcommons.unl.edu/insectamundi/514

This Article is brought to you for free and open access by the Center for Systematic Entomology, Gainesville, Florida at DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in Insecta Mundi by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln. Vol. 1, no. 4, December 1986 INSECTA MUNDI 22 1 STINGS OF ANTS OF THE TRIBE PHEIDOLOGETINI (MYRMICINAE)

Charles Kugler

Biology Department, Radford University, Radford, VA 24142 USA

The definition of the Tribe Pheidologe- ted in Canada balsam. For more details, see tini in the ant subfamily Myrmicinae has Kugler (1978a). Preparations were examined always been problematic. Emery (1922) erec- with a Zeiss KF-2 phase contrast microscope ted the tribe to contain the genera Pheido- at 400X magnification. Drawings and meas- logeton, Oligomyrmex, Aneleus, Lophomyrmex, urements were made using a grid eyepiece, Trigonogaster, Ekebomyrma, Carebara and Pa- with estimated accuracy of +0.001mm. In dalgus, but Wheeler (1922) put all these measurement of regions of sting, the bound- genera in the Solenopsidini. Neither Emery ary between the sting shaft and valve cham- nor Wheeler satisfactorily defined either ber is the point of closest approximation of tribe. More recently, Ettershank (1966) outer and innner walls at the~posteriorend proposed the "Pheidologeton genus group" of the valve chamber; the boundary between composed of Pheidologeton, Oligomyrmex (in- valve chamber and sting bulb is the anterior cluding most Aneleus), Lophomyrmex, Care- end of the internal apophysis. In Oligomyr- bara, Paedalgus and Anisopheidole, but still mex, I could not discern precisely the end uncertainty remains as to relationships of of the apophysis, so used instead the middle these genera and even the definitions of the of the transverse ridge, which is near the genera themselves. New characters and new end of the apophysis in other genera. The means of analysis are needed to help resolve Index of Reduction (IR) is a measure of the this problem. length of the sting relative to the size of In earlier studies of the myrmicine the ant: (pronotal Wlsting L) X 100. Sen- sting apparatus (Kugler, 1978a. 1978b), I silla counts on gonostyli include the dorso- found that the eight sclerites constituting terminal chaeta and companion seta. Scale the sting apparatus are a rich source of lines in all figures are 0.05mm. characters that vary between genera. More- Species examined: Anisopheidole anti- over, the sting apparatus was generally podum(1 major, 1 minor) Australia: W. Aus- uniform within those genera for which sev- tralia, Manjimup, W. S. Brooks, leg. Lopho- eral species were examined. Thus, the sting myrmex bedoti (5 workers) Indonesia: Rali- apparatus holds promise for helping define mantan, Pleihari-Martapura Reserve, 3 July myrmicine genera and analyzing phyletic 1983, M. W. Moffett, leg. Lophomyrmex opa- relationships among them. ciceps (2 workers) Indonesia, W. Java, Ujung In this paper I describe and compare Kulon National Park, 1 Sept. 1983, M. W. the sting apparatuses of Pheidologeton, Moffett, leg. Pheidologeton diversus (1 Oligomyrmex, Trigonogaster, Lophomyrmex, and major, 1 media, 3 minors) Malaysia, Singa- Anisopheidole. The first three were de- pore, Botanic .Gardens, 31 Oct. 82, M. W. scribed in Kugler (1978a), but only on the Moffett and D. A. Fletcher, leg.; and N. basis of single species and few specimens. Celebes, Tangkoko-Batuangus Res., W. L. Here their descriptions are extended to Brown, leg. Pheidologeton nanus (1 major, 1 better see how the sting apparatus varies media, 2 minors) India, Kerala State, Peri- between castes and between species within yar Tiger Preserve, 8 Mar. 82, M. W. Mof- genera. f ett, leg. Pheidologeton pygmaeus (2 ma- jors, 3 minors) Malaysia, Penang, Penang Hill, colony #08-83, M. W. Moffett, leg. Each sting apparatus was removed from Pheidologeton silenus (1 major, 1 minor) the ant, cleared in hot lactophenol solu- Malaysia, Sarawak (1st Division) Samunsam tion, and usually dissected further into Wildlife Sanct., May 28, 1983, M. W. Mof- two halves and a sting. Stings and some- fett, leg. Oligomyrmex corniger? (near times whole apparatuses were mounted in sodalis) (1 major, 1 minor) New Caledonia, glycerin jelly for ease of positioning and Mt. Mou, Dec. 10, 1954, #109, E. 0. Wilson, repositioning in exact lateral, dorsal and leg. Oligomyrmex overbecki (2 major, 2 other views. The other sclerites were moun- minor workers) Singapore, Botanic gardens, 222 INSECTA MUNDI Vol. 1, no. 4, December 1986 December, 1983, M. W.Moffett, leg. Oligo- abruptly narrowed midlength. No segmenta- nyrnex sp. 2 (1 major, 1 minor) Australia, tion. Dorsoterminal chaeta and companion N. Queensland, Eungella, B. Hblldobler , leg. seta may be sparated from other sensilla by Oligomyrmex (Erebomyrma) urichi (1 minor) a gap, but generally not. Sensilla: 7-12 Trinidad, Oropouche Cave near Cumaca, 18 trichodea, 6-7 chaetica, 0-2 basiconica. June 1961, E. 0. Wilson, leg. Oligonyrmex Triangular plate: (Fig. 1) Moderately (Nimbanyrnex) villiersi (?) (1 minor) Bel- wide-bodied; not elongate; no dorsal or gian Congo, Ituri Forest vic., Epulu, July, medial tubercles. 1955, No. 6, T. Gregg, leg. Trigonogaster Lancet: (Fig. 1) Short, weak; apex sp. 1 (2 workers) Indonesia, Central Sula- acute, flexible, lacking barbs. Two small wesi, Lore Lindu N. P. at Toro, 14 July, valves per lancet; posterior valve highly 1983, M. W. Moffett and D. A. Fletcher, reduced. leg. Trigonogaster sp. 2 (1 worker) and Trigonogaster recurvispinosa (1 worker) In- Sting: (Figs. 2,3) Sting shaft reduced donesia, Bali, Monkey forest at Ubud, 18 in length (38-41% of sting length), weak, August, 1983, M. W. Moffett and D. A. Flet- lacking campaniform sensilla; apex laterally cher, leg. Trigonogaster sp. 3 (2 workers) compressed to form a flexible, spatulate Malaysia, Gombak field station, November, flange. Flange larger in P. diversus and 1983, M. W. Moffett and D. A. Fletcher, leg. especially P. nanus (Fig. 3). Valve chamber Vouchers of all species will be de- 19-25% of sting L; profile distinct from posited in the Museum of Comparative Zoolo- sting bulb, but not from sting shaft; inter- gy, Harvard University with the label nal apophysis touches dorsal wall of sting. ''VOUCHER Sting Dissection, Kugler 1984;' Sting wall at boundary between sting bulb and valve chamber thickened into a wide, transverse, internal ridge. Sting bulb 34- 42% of sting L, very wide, but sharply ta- Majors of P. silenus; majors and medias of pered to narrow, weakly arched sting base P. diversus and P. nanus. with thick basal ridge. Bulb more vaulted in P. diversus major, approaching the shape Spiracular plate: (Fig. 1) Nearly of minors (Fig. 5) Basal notch very wide square, larger than quadrate plate. An- dorsoventrally. IR = 11-15. terior apodeme not extending onto partially Furcula: (Figs. 2.3) Reduced to a membranous medial connection. No postero- thick, subtriangular sclerite tightly fused dorsal lobe or dorsal notch. Posteroventral to top of sting base. No dorsal arm. corner not elongate. Spiracle not enlarged. Apodeme wider in P. nanus. Posterodorsal Minors of P. silenus, P. diversus, and P. corner of P. diversus media reduced and nanus . approaching condition in minors (Fig. 4). Quadrate plate: (Fig. 1) Body wider Spiracular plate: (Fig. 4) More trian- than apodeme; anterior and dorsal ridges gular than in major, due to reduction of thick, forming a prominent, well sclerotized pos terodorsal corner. anterodorsal corner with lateral and medial Quadrate plate: (Fig. 4) Anterior edge lobes. In P. silenus and P. nanus, pos- concave. Body wider than apodeme, with terior edge of body with a concave notch in notched posterior margin. Anterodorsal cor- dorsal half; P. diversus not notched. ner without lobes; pollicate in P. diversus, Anal plate: Much wider than long, with more elongate in P. silenus (Fig. 4) and P. ill defined edges. Setae arranged as in nanus . minors (Fig. 4) along posterior margin in Anal plate: (Fig. 4) Posterior margin two lateral patches; 9 setae in P. silenus more convex than in major; with fewer (3-5) and P. diversus; 5-6 in P. nanus. setae. Oblong plate: (Fig. 1) Not divided Oblong plate: (Fig. 4) Shape like that into posterior and ventral arms by a postin- of major. Sensilla: 2 intervalvifer, 1 cision. Dorsal ridge with subterminal tu- ramal, 0 fulcral. bercle and long posterior apodeme. Anterior Gonostylus: (Fig. 4) Same basic shape apodeme not especially elongate. Fulcra1 as in major, but narrow distal portion shor- arm weakly sclerotized, 'oval. Sensilla: 3- ter. Fewer sensilla than in major: 5-7 6 intervalvifer, 3-9 ramal, 2-6 fulcral. trichodea, 2-3 chaetica, 0 basiconica. Numbers can vary between two halves of same Triangular plate: (Fig. 4) Body more apparatus, and are generally larger in lar- slender than in major. ger individuals. Lancet: (Fig. 4) As in major, but with Gonostylus: (Fig. 1) Wide basally, but single, highly reduced valve. Vol. 1, no. 4, December 1986 INSECTA MUNDI 223 Sting: (Fig. 5) Sting shaft short; Sting bulb short (14% of sting L); not high- seems to retain small apical flange, but er than valve chamber. Sting base in ven- possibly not (see Kugler 1978a, Fig. 235). tral view convex, without anterolateral Valve chamber even less distinguishable from processes. Basal ridge present, weakly sting shaft than in majors. Sting bulb more arched in anterior view. Relative to body vaulted in lateral view; without internal size, sting longer in minors than in majors ridge. Total sting L (relative to body (IR minors = 72, majors = 53). size) similar to majors (IR = 12-14), but Furcula: (Fig. 7) Ventral arms tightly sting bulb proportionately longer (51-56% of fused to sting base. Dorsal arm large, sting L) at expense of shorter valve chamber projecting anteriorly. (11-17%) and sting shaft (30-33%). Furcula: (Fig. 5) A transverse bar fused to the dorsal side of sting base, with narrower extremities extending onto sides. OLI-

Major and minor of Pheidologeton pygaaeus. Majors of 0. corniger, 0. overbecki, and 0, sp. 2 Spiracular plate: (Fig. 6) Smaller than quadrate plate; shape subtriangular due Spiracular plate: In 0. sp. 2 and 0. to reduction of posterodorsal corner. Body corniger (Fig. 8A), large, oval, with pos- weakly sclerotized, grading into membranous terodorsal corner. Anterior apodeme narrow; medial connection. Posteroventral corner medial connection membranous. Spiracle notched. Spiracle small. small, near center of plate. Plate of 0. Quadrate plate: (Fig. 6) Weakly scle- overbecki more triangular and with larger rotized; ventral end much narrower than spiracle, much as in minor of 0. corniger dorsal end. Apodeme mostly wider than body; (Fig. 8B). anterodorsal corner lightly sclerotized, Quadrate plate: (Fig. 8A) Apodeme and short, without lobes. Body grades into body subequal in width, posterior margin not membrane caudally and dorsally. notched. Anterodorsal corner thickened, but Anal plate: Longer than wide, with without lobes; corner shape differs in dif- weakly defined perimeter. Posterior margin ferent species: pollicate in 0. corniger with 8-9 long, evenly spaced setae. (Fig. 8A); as long, but narrower in 0. over- Oblong plate: (Fig. 6) Not divided becki; reduced to a broadly rounded corner into posterior and ventral arms by a postin- in 0. sp, 2. cision. Dorsal ridge narrow, its distal end Anal plate: Shape subtriangular. Sen- tapered; no subterminal tubercle. Body silla marginal, in two lateral patches. weakly sclerotized, grading into membrane With two setae in 0. overbecki; four in 0. ' caudally. Fulcral arm short, weak, spindle- corniger; number unclear in 0. sp. 2. shaped. Sensilla: 3 intervalvifer, 3 ra- Oblong plate: Very similar in the mal, 0 fulcral. three species, and much like that of Pheido- Gonostylus: (Fig. 6) Slender, single- logeton pygmaeus (Fig. 6). Not divided into segmented, uniformly sclerotized except for posterior and ventral arms by a postinci- membranous apical flange. Sensilla bimodal- sion. Posterior apodemes long. Fulcral arm ly distributed with dorsoterminal chaeta and weak, spindle-shaped, with poorly defined companion seta isolated at apex. Sensilla: dorsal limb. Sensilla: 2-3 intervalvifer, 1-4 trichodea, 2 chaetica, 0 basiconica. 3-6 ramal, 0 fulcral. Triangular plate: (Fig. 6) Body slen- Gonostylus: As in P. pygmaeus (Fig. der; no dorsal or medial tubercles. 6). Single segmented, short, tapered in Lancet: (Fig. 6) Long, slender, mod- distal half. Dorsoterminal chaeta and com- erately sclerotized; apex tapered to sharp panion seta present in 0. corniger and 0. point with single small barb. Dorsal ridge sp. 2; companion seta not present in 0. indistinct. Lancet valves large, one per overbecki. Sensilla: 2-6 trichodea, 2 lancet. chaetica, 0 basiconica. Sting: (Fig. 7) Sting shaft long (59- Triangular plate: Shape in all three 60% of sting L) slender, straight, and species as in P. pygmaeus (Fig. 6). No acute; proximal half with 2-3 pairs of cam- medial or dorsal tubercles. paniform sensilla; no terminal flange- Lancet: Strong and acute as in P. Valve chamber long (25-27% of sting L) and pygmaeus (Fig. 6). but with more reduced, high, its profile distinct from sting shaft, barely visible barb. Two valves per lancet internal apophysis held away from dorsal in 0. corniger and 0, sp. 2; only one visi- wall of sting by a narrow internal ridge. ble in 0, overbecki. 224 INSECTA MUNDI Vol. 1, no. 4, December 1986 Sting: In 0. corniger (Fig. 9) and 0. ter, with a weak, acute apex and no trace of sp. 2 tapered from base to apex, valve cham- a barb. ber and sting bulb without distinct pro- Sting: 0. overbecki, 0. sp. 2, and 0. files. Sting shaft long (61% of sting L), villiersi with stings like that of major of strong, acute. Campaniform sensilla present 0. overbecki (Fig. 11). 0. corniger (Fig. in 0. corniger and 0. sp. 2. Valve chamber 10) similar, but with narrower basal notch very low, 21% of sting L, separated from (Fig. 10 is a refinement of Figs. 233-234 in sting bulb by a large, transverse internal Kugler 1978a). 0. urichi (Fig. 12) has a ridge. Sting bulb very short (18% of sting much shorter, weaker sting shaft (40% of L), with large basal notch and narrow sting sting L, compared to 52-592 in other spe- base. In 0. overbecki majors (Fig. ll), cies), a relatively large sting bulb, and no valve chamber more vaulted and articular internal ridge. None have campanif orm sen- processes more slender than in other spe- silla. cies, but lengths of parts are similar Furcula: (Figs. 10,11,12) In all spe- (sting shaft = 60% of sting L, valve chamber cies, reduced to a small sclerite tightly = 212, and sting bulb = 19%). fused to the sting base. Furcula: (Figs. 9,lO) A bar tightly fused to top of sting base in all three species.

Minor workers of 0. corniger, 0. overbecki, 0. sp. 2, 0. villiersi, and 0. urichi. Monomorphic workers of L. bedoti and L. opaciceps, Spiracular plate: Triangular in 0. corniger (Fig. 8B), 0. overbecki, and 0. Spiracular plate: (Fig. 13) Triangular urichi, due to reduced posterodorsal corner; in L. bedoti (Fig. 13) to subtriangular in spiracle near posterior edge. Spiracle in L. opaciceps due to reduction of posterodor- 0.corniger and 0.overbecki large relative sal corner. Anterior apodeme narrow, but to size of plate. Anteroventral corner forming a sclerotized medial connection elongate in 0. urichi. Plate poorly pre- between hemitergites. Posteroventral corner served in 0. sp. 2 and 0. villiersi prepara- narrow and elongate. Spiracle large. tions. Quadrate plate: (Fig. 13) Tapered Quadrate plate: In 0. corniger, 0. sp. ventrally. Apodeme area in L. bedoti sube- 2, and 0. villiersi, similar to that of 0. qua1 to area of body; in L. opaciceps, twice corniger major (Fig. 8A). Anterodorsal the width of the body. Posterior edge not corner in 0. overbecki narrower, as in the notched. Anterodorsal corner prominent, 0. overbecki major. Anterodorsal corner in wide, with small medial lobe. 0. urichi elongate as in the minor of Phei- Anal plate: Slightly wider than long, dologeton silenus (Fig. 4) with indistinct margins. Posterior margin Anal plate: Shape triangular in 0. with 6 to 8 long setae in two clusters overbecki; unclear in others. In 0. corni- separated by a weak median gap. ger, 0. urichi, and 0. villiersi, with 2-3 Oblong plate: (Fig. 13) Divided into marginal, laterally placed setae, as in distinct posterior and ventral arms by a minor of P. silenus (Fig. 4). postincision. Posterior arm with slender Oblong plate: In 0. corniger, 0. over- dorsal ridge terminating as a long posterior becki, 0. urichi, and 0. villiersi as des- apodeme that nearly connects medially with cribed for majors, except for lack of a its counterpart; no subterminal tubercle dorsal extension of fulcral arm. Sensilla: present. Anterior apodeme long and slender. 2 intervalvifer, 1-5 ramal, 0 fulcral. Fulcra1 arm large, extending to postinci- Gonostylus: Shape in all species much sion, anterior edge ridged. Sensilla: 1-2 like that of P. diversus minor worker (Fig. intervalvifer, 2 ramal, 0 fulcral. 4). All but 0. urichi with a gap separating Gonostylus: (Fig. 13) Single segmen- dorsoterminal chaeta and companion seta from ted, uniformly sclerotized. Slender, evenly others. Sensilla: 4-5 trichodea, 1-2 chae- tapered in lateral view, but markedly nar- tica, 0 basiconica in 0. corniger, 0. vil- rowed midlength in dorsal view. Long mem- liersi, and 0. urichi; others unclear. branous terminal flange present. Sensilla Triangular plate: All species as in bimodally distributed; dorsoterminal chaeta majors, except for 0. urichi, in which body and companion seta may be isolated or accom- is unusually narrow. panied by 1-2 shorter setae; some basal Lancet: Strong, acute as in majors, setae may be very long. Sensilla: 5-8 tri- except for 0. urichi, in which it is shor- chodea, 1-2 chaetica, 0-1 basiconica. Vol. 1, no. 3, December 1986 INSECTA MUNDI 225 -- Triangular plate: (Fig. 13) Body and lobes slender. No dorsal or medial tuber- cles. Major and minor of A, antipodum. Lancet: (Fig. 13) Long and gradually tapered to very acute, but weak apex. L. Spiracular plate: (Fig. 15) Pos- bedoti with two small valves per lancet, the terior and dorsal sides merge, eliminating posterior valve reduced (Fig. 13); L. opaci- posterodorsal corner. Medial connection ceps with one valve. between hemiternites sclerotized. Spiracle in center of plate, not enlarged. Sting: (Fig. 14) Sting shaft long, Quadrate plate: (Fig. 15) Anterodorsal slender, very weak, twisted in all prepara- corner especially broad and prominent, mak- tions. Sides taper and disappear subtermi- ing whole anterior edge of plate concave. nally, beyond which the dorsal wall dilates No medial or lateral lobes. slightly in both lateral and ventral views Anal plate: Weakly sclerotized with then ends with a short truncate shelf. One ill-defined perimeter; about three times pair of campaniform sensilla at base of wider than long. Setae located medially on sting shaft. Valve chamber low, its profile posterior margin; contrary to the rule, more indistinct from the sting shaft and sting in the minor (5) than the major (2). bulb. Junction of valve chamber and sting Oblong plate: (Fig. 15) Not split into bulb with large tubercle projecting down posterior and ventral arms by a postinci- from the dorsal wall. Sting bulb long, but sion. Dorsal ridge strong, gradually widen- not especially wide, oval in ventral view; ing caudad, forming a shelf that, seen from basal notch long, low; articular processes above, looks much like a right triangle; no small. Sting base narrow, weakly arched in subterminal tubercle or distinct posterior anterior view, basal ridge lost medially. apodeme. Anterior apodeme thick, blunt. Sting proportions: Sting shaft = 48% of Fulcra1 arm short, thin, spindle-shaped in sting L, valve chamber = 15%, sting bulb = major; unclear in minor. Sensilla: 2 in- 36%. IR = 27. tervalvifer, 6 ramal in major, 4 ramal in Furcula: Reduced to a bar fused to the minor, 0 fulcral. sting base. Narrow in L, bedoti (Fig. 14). Gonostylus: (Fig. 15) Single segmen- wider and more shelf-like in L. opaciceps. ted; distal two thirds tapered to narrow tip. Sensilla distributed without gaps; dorsoterminal chaeta present in minor, not detectable in major; no obvious companion seta. Sensilla: major with 10-13 trichodea, 3-4 chaetica, 5-6 basiconica; minor with 11 Monomorphic workers of T. recurvispinosa and trichodea, 1 chaetica, 2 basiconica. 3 unidentified species. Triangular plate: Body thick, nearly square in major (Fig. 15); more slender in None of these differs significantly minor. from the single T. recurvispinosa worker Lancet: (Fig. 15) Tip acute, but weak- described by Kugler (1978a:472-473, Figs. ly sclerotized, probably unable to pierce; 186-187), so I will only supplement that one valve per lancet. description. Anal plate a little wider than Sting: (Fig. 16) Sting shaft long (49- long, with broadly rounded posterior margin; 53% of sting L) slender, acute, but weakly 4-9 marginal to submarginal setae, with sclerotized; with one pair of campaniform little or no median gap. Anterodorsal cor- sensilla. Valve chamber short (13% of sting ner of quadrate plate short, narrow, without L), low, with weakly differentiated profile. lobes. Gonostylus from above wide at base, Sting bulb long (33-38% of sting L), low in evenly tapered to broadly rounded apex with side view; very wide, nearly square in ven- long membranous extension; 5-6 long sensilla tral view; with no internal ridges or tuber- trichodea, 1 s. chaetica, 0 basiconica; no cles. Sting base arched in anterior view, gap separating dorsoterminal chaeta and with wide basal ridge. IR = 21 in the companion seta from others; microtrichae on major; 36 in the minor. medial side of gonostylus very long and dense. Lancet apex spatulate, but not en- Furcula: (Figs. 15, 16) Arched, trans- larged. Sting with small internal tubercle verse, articulating with anterolateral pro- of same shape and position as in Lophomyrmex cesses of sting base. No dorsal arm. (Fig. 14); sting base in some species with small anterolateral processes as in Cremato- gaster (Kugler 1978a, Fig, 184). 22 6 INSECT'A MUNDI Vol. 1, no. 4, December 1986

DISCUSSION the minors, and 4) in both species the shapes of the valve chamber and sting bulb Variation within Genera are much different in the two castes. The variation between species of Oligo- Intercaste variation in Pheidologeton myrmex ranges from little to marked. 0. is strong in P. nanus, P. diversus, and P. corniger and 0. sp, 2 are very nearly iden- silenus, especially in shapes of the spira- tical in sting apparatus morphology, except cular plate, quadrate plate, gonostylus and for the shape of the anterodorsal corner of sting, and in numbers of sensilla, which the quadrate plate in the majors. 0. over- appear correlated with ant size. becki differs from those two species only in Little interspecific variation is seen having the sting of the major the same as between P. silenus, P, diversus and P, na- the minor. The lack of a stronger sting in nus, and most of that is in the major caste. the majors of 0. overbedci may be a function Differences occur mainly in the sizes and of size, since these majors are about the shapes of the spiracular plate, the sting same size as the minors of 0. sp. 2. For shaft flange, and the furcula. the remaining two species the major worker In contrast, the apparatus of P. pyg- was unavailable for study. The sting appa- maeus differs substantially from those of ratus in the minor of 0. villiersi is like the other Pheidologeton in the following that of 0. sp. 2, but the apparatus of 0. ways: 1) it is monomorphic, 2) the spiracu- urichi minors differs from those of the lar plate is smaller than the quadrate plate other four species in a number of ways: 1) and its shape is subtriangular even in the the anterodorsal corner of the quadrate majors, 3) the quadrate plate lacks medial plate is more elongate and digitate, 2) the and lateral lobes even in majors, 4) the gonostylus lacks the gap between distal and anal plate is longer than wide, rather than proximal sensilla, 3) the triangular plate transverse, and has no median gap in the is much narrower, 4) the lancet has a flexi- setae, 5) the base of gonostylus is narrow- ble, more abruptly tapered apex, and 5) the er, 6) there is only a single pair of lancet sting lacks a transverse internal ridge and valves, which are much larger than in other has a shorter, weaker sting shaft. These Pheidologeton examined, 7) the lancets are characteristics of 0. urichi look like typi- strong, sharp, and barbed, 8) the sting cal reductions in the apparatus with loss of shaft is strong, piercing, and without a the stinging function. terminal flange, 9) the valve chamber is Lophomyrmex has monomorphic workers, much larger, and 10) the furcula has a pro- and only one species was examined. The five minent dorsal arm. The differences in sting workers of that species varied only in num- and lancets indicate that P. pygmaeus can bers of sensilla. sting, but not P. silenus, P. diversus, or Trigonogaster workers are also monomor- P. nanus. This is confirmed by Mark W. phic, and in the four species examined the Moffett, who says that P. pygmaeus has a sting apparatus varied only slightly in tt vicious sting," whereas the other Pheidolo- shape of the spiracular plate and in the geton discussed here do not sting at all numbers and positions of sensilla. (personal communication). The flange on the Anisopheidole contains only the species sting shaft of P. nanus, P. diversus, and P. antipodum. The one major and one minor silenus is probably for airing or applying a examined differed slightly in: 1) numbers defensive fluid. of sensilla, 2) thickness of the triangular Intercaste variation in Oligomyrmex can plate, 3) proportions within the sting (ma- be discussed for three species. In 0. over- jors with a slightly longer sting bulb and beckithere is very little difference be- slightly shorter sting shaft), and 4) the tween majors and minors in characteristics index of reduction (sting relatively larger of the quadrate plate, anal plate, oblong in minors). plate, triangular plate, lancet, sting or furcula. Lack of a good spiracular plate Comparisons of Genera preparation for the major prevents compari- son. In 0. corniger and 0. sp. 2 there is Oligomyrmex and Pheidologeton (exclud- marked dimorphism in some sclerites: 1) the ing P. pygmaeus) share several sting appara- spiracular plate is oval in the majors of 0. tus characters that are advanced within the corniger and triangular in the minors, 2) Myrmicinae: 1) the sting bulb wide at the the anterodorsal corner of the quadrate articular processes, but tapering sharply to plate in 0, sp. 2 minors is longer than in a narrow sting base with a similarly shaped majors; 3) in both species the fulcra1 arm and positioned furcula, 2) the dorsoventral- of the oblong plate is shorter and weaker in ly wide basal notch, and 3) the transverse Vol. 1, no. 4, December 1986 INSECTA MUNDI 227 internal ridge (though somewhat different in sting apparatus would indicate somewhat shape and position), 4) the oblong plate greater af f inities of pygmaeus with Oligo- without a postincision and with a short, myrmex than with Pheidologeton. spindle-shaped fulcra1 arm, and 5) the part- The sting apparatuses of the two Lopho- ly membranous medial connection between the myrmex species examined are not clearly al- spiracular plates. These characters are lied with those of either Pheidologeton or thus far a unique combination of characters Oligomyrmex. It does share some derived within the Myrmicinae, even though the sting characters with Pheidologeton, such as weak bulb form (character 1 above) is found in sting and lancets, and (with Oligomyrmex Myrmecina, the internal ridge of the sting also) lack of a dorsal arm on the furcula, is found in Proatta, Cardiocondyla, Trano- but these are common convergences that occur pelta, and Hyrmicaria, and the membranous whenever the stinging function is reduced or medial connection of the spiracular plates lost. On the other hand, the internal tu- is found in a variety of genera (Kugler bercle in the sting is an unusual feature 1978a, Appendix Al). Among most species that is found in Hyrmicaria, Tranopelta examined, Oligom yrmex and Pheidologeton gen- (Kugler 1978a, Figs. 175, 230), and Trigono- erally differ markedly in strength and form gaster. Hyrmicaria and Tranopelta stings of their sting shafts and lancets and in the otherwise do not resemble that of Lophomyr- form of the quadrate plates of the minor =ex, but the apparatus of Trigonogaster does workers, but the apparatus of the 0. urichi in some ways: the form of the sting bulb in minor (Fig. 12) is much like that of a lateral and ventral views, the long, flexi- Pheidologeton minor (Fig. 5). This strong ble, often twisted sting shaft, and the similarity of the sting apparatuses of Oli- enlarged spiracle. These comparisons of the gomyrmex and Pheidologeton supports the sting apparatus support the conclusions of views of Emery (1922), W. M. Wheeler (1922), Wheeler and Wheeler (1953), who, after com- Wheeler and Wheeler (1953). and Ettershank paring pheidologetine larvae, distanced (1966) that these are closely related gen- Lophomyrmex from Oligomyrmex and Pheidologe- era. ton somewhat by putting it in a separate I have separated Pheidologeton pygmaeus subtribe with Trigonogaster. from the other three Pheidologeton because The Trigonogaster apparatus, in turn, of differing opinions on the generic place- seems most related to that of Crematogaster. ment of this species. According to Emery The spiracular, quadrate, oblong plates and (1922) pygmaeus belonged in Aneleus, but furcula in these two genera are very similar then Ettershank (1966) transferred pygmaeus (Kugler 1978a:472-473). as are the lancets to Pheidologeton and the other Aneleus spe- and sting base. Crematogaster minutissima cies to Oligomyrmex. Looking at the sting also has a median tubercle in the sting like apparatus, there are many striking differen- Trigonogaster. The Crematogaster gonostyli, ces between the pygmaeus and the other Phei- however, do not have the long sensill'a and dologeton. Most of these are due to the extraordinarily long microtrichae found in retention of a primitive stinging sting the four Trigonogaster species. apparatus in pygmaeus while the other three The apparatus of Anisopheidole antipo- species have acquired stings modified for dum, has more similarities with those in the chemical defense. I do find three derived Pheidole genus group (Kugler 1978a) than characters in common, but these could easily with the other genera discussed here. For be convergences: the fused furcula, membra- example, the sting in ventral view is much nous medial connection of the spiracular like that of Hessor, and in lateral view is plates, and the lack of a postincision. P. similar to Stenamma's (Kugler 1978a, Figs. pygmaeas seems more similar to Oligomyrmex, 139, 146). The gonostylus and lancets also partly because most species of the latter resemble those in some members of the Phei- that I examined also had piercing stings. dole group. Ettershank (1966) put Aniso- In fact, the pygmaeus sting would look a lot pheidole in the Pheidologetini, primarily on like that of 0. overbecki if its valve cham- the strength of a wing venation character, ber and furcula were smaller. However, some but as Brown (1953) pointed out, Anisophei- characteristics shared with Oligomyrmex may dole's external morphology shows "...certain be derived: the same shape and position of features in common with Pheidole and Stenam- the transverse internal ridge in the sting ma." Indeed, it was long considered a sub- bulb, and the structure of the oblong plate genus of Pheidole. Since sting apparatus (in addition to the furcula, spiracular morphology also shows features in common plate and postincision characteristics men- with the Pheidole group, we might reevaluate tioned above that pygmaeus also shares with Anisopheidole's present position near Phei- Pheidologeton). This comparison of the dologeton. 228 INSECTA MUNDI Vol. 1, no. 4, December 1986 It would be premature to try to charac- terize the "pheidologetine sting apparatus" or to say what genera belong in the Pheido- Brown, W. L., Jr. 1953. Characters and logetini, since I have not been able to synonymies among the genera of ants. study all the necessary genera, and because Part 11. Brev. Mus. Comp. Zool. Harv. of the diversity of stings among the genera 18: 1-8. examined. However, the following conclu- Emery, C. 1922. Subfam. Myrmicinae. Gen. sions do seem warranted and should be useful Insect. 174:l-397, 7 pls. (1921-1922). to future reviewers of the tribe. On the Ettershank, G. 1966. A generic revision of basis of the sting apparatus alone: 1) the world Myrmicinae related to Solen- Pheidologeton and Oligomyrmex are close1y opsis and Pheidologeton (Hymenoptera: related, 2) Pheidologeton pygmaeus is closer Formicidae). Aust. J. 2001. 14:73-171. to Oligomyrmex than to Pheidologeton, 3) Kugler, C. 1978a. A comparative study of Lophomyrmex and Trigonogaster seem related the myrmicine sting apparatus (Hymenop- and possibly closer to rem ma tog aster than to tera, Formicidae). Stud. Entomol. Pheidologeton and Oligomyrmex, and 4) Aniso- 20:413-548. pheidole has more affinities with the Phei- -1978b (1979). Further studies of the dole genus group (sensu Kugler 1978a) than myrmicine sting apparatus: Eutetramor- with Pheidologeton and Oligomyrmex. ium, Oxyopomyrmex, and Terataner (Hy- menoptera, Formicidae). Psyche 85255- 263. Wheeler, G. C., and J. Wheeler 1953. The ant larvae of the myrmicine tribe Phei- dologetini. Psyche 60:129-147. I am very grateful to Mark W. Moffett Wheeler, W. M. 1922. Keys to the genera and for supplying specimens and determinations, subgenera of ants. Bull. Am. Mus. Nat. to William L. Brown, Jr. for reviewing the Hist. 45:631-710. manuscript, and to Janet M. Hahn for edito- rial assistance. Opinions expressed are entirely my own.

Figs. 1-3. Pheidologeton silenus and Phei- apodeme; bn, basal notch; br, basal ridge; dologeton nanus major workers. 1. Right cs, companion seta; dr, dorsal ridge; dtc, half of P. silenus sting apparatus minus dorsoterminal chaeta; fa, fulcral arm; f 1, sting and furcula. Spiracular and quadrate flange; fs, fulcral sensilla; FU, furcula; plates separated from the triangular plate; GO, gonostylus; ia, internal apophysis; ir, gonostylus in ventrolateral view. 2. P. internal ridge; ivs, intervalvifer sensilla; silenus sting and furcula in lateral view LA, lancet; mc, medial connection of spira- (above) and ventral view (below). 3. P. cular plates; OP, oblong plate; QP, quadrate nanus sting shaft in lateral view; sting and plate; rs, ramal sensilla; sblb, sting bulb; furcula in ventral view. Abbreviations SP, spiracular plate; ss, sting shaft; TP, (names of sclerites in upper case): adc, triangular plate; vc, valve chamber; vlv, anterodorsal corner of quadrate plate; apo, valves of lancet. Vol. 1, no. 4, December 1986 INSECTA MUNDI 229

Figs. 4-5. Pheidologeton silenus minor worker. 4. Right side of sting apparatus minus sting and furcula. 5. Sting and fur- cula in lateral view (above) and ventral view (below). Abbreviation: AP, anal plate.

Figs. 8-12. Oligoryrmex. 8. 0. corniger. A. Spiracular and quadrate plate of major worker. B. Spiracular plate of minor wor- ker. 9. 0. corniger major worker sting and furcula in lateral view (above) and ventral Figs. 6-7. Pheidologeton pygmaeus. view (below). 10. 0. corniger minor worker 6. Right side of minor worker sting appara- sting and furcula in lateral and ventral tus minus sting and furcula; gonostylus in views. 11. 0. overbecki major worker sting ventral view. 7. Lateral view, sting and and furcula in lateral and ventral views. furcula of minor worker (above); ventral 12. 0. urichi minor worker sting and furcula view, major worker (below). in lateral and ventral views. 230 INSECTA MUNDI Vol. 1, no. 4, December 1986

Figs. 13-14. Lophonyrrex bedoti 13. Right Figs. 15-16. Anisopheidole antipodur. side of sting apparatus minus sting and 15. Right side of sting apparatus minus furcula; gonostylus in ventral view. 14. sting and furcula; gonostylus in dorsal Sting and furcula in lateral view (above) view. 16. Sting and furcula in lateral view and ventral view (below). (above) and ventral view (below).