J. HYM. RES. 2(1), 1993 pp. 117-168 Systematic studies on Pseudomyrmex acacia-ants (Hymenoptera: Formicidae: Pseudomyrmecinae) PHILIP S. WARD Department of Entomology, University of California, Davis, CA 956 1 6 Abstract. The obligate acacia-ants ( Pseudomyrmex ferrugineus group) are well known as defensive inhabitants of swollen-thorn acacias in the northern Neotropics. A taxonomic revision of these ants leads to the recognition of ten species: P. ferrugineus (F. Smith), P. flavicornis (F. Smith), P. janzeni, sp. nov., P. mixtecus, sp. nov., P. nigrocinctus (Emery), P. particeps, sp. nov., P. peperi (Forel), P. satanicus (Wheeler), P. spinicola (Emery), and P. veneficus (Wheeler). The following new synonymy is proposed: P. nigrocinctus = P. alfari (Forel) = P. bicinctus (Santschi) = P. peltatus (Menozzi); P. spinicola = P. atrox (Forel) = P. gaigei (Forel) = P. infernalis (Wheeler) = P. scelerosus (Wheeler). Diagnostic descriptions and taxonomic comments are also provided for ten other unrelated species of Pseudomyrmex which have become secondarily associated with swollen-thorn acacias either as obligate and, in at least one case, parasitic occupants (P. nigropilosus (Emery), P. simulans Kempf and P. subtilissimus (Emery); P. reconditus, sp. nov., may also belong in this category) or as facultative inhabitants ( P. boopis (Roger), P. gracilis (Fabricius), P. hesperius, sp. nov., P. ita (Forel), stat. nov., P. kuenckeli (Emery) and P. opaciceps, sp. nov.). A cladistic analysis of the P. ferrugineus group yields the following result which appears to be fairly robust insofar as there is congruence among the trees derived from worker-, queen-, and male-based character sets: ((nigrocinctus + particeps) + (peperi + ((satanicus + spinicola) + ferrugineus complex))). The "ferrugineus complex" comprises five species whose phylogenetic relationships are not fully clarified. The composite data set (47 characters from all three castes) supports the following partial resolution: (ferrugineus + janzeni + (flavicornis + (mixtecus + veneficus))). The cladogram of the P. ferrugineus group indicates that speciation in the group has occurred primarily as a consequence of geographical isolation, and that the ants and their host acacias have experienced diffuse coevolution rather than strict cospeciation. INTRODUCTION men ts have appeared in the ecological literature. In this paper I present a taxonomic revision of the Pseudomyrmex ferrugineus (F. Smith) and re- obligate acacia-ants (Pseudomyrmex ferrugineus lated species of ants form a well-defined mono- group) and an assessment of their phylogenetic phyletic group, the members of which nest exclu- relationships. I also attempt to clarify the identities sively in the hollow, swollen thorns of several New of other, unrelated species of Pseudomyrmex which World Acacia species. Because of their aggressive have become secondarily associated with swollen- behavior and predictable occurrence on the acacias, thorn acacias. these ants have received considerable attention The earlier taxonomic literature on acacia-ants from tropical biologists (Belt 1874; Safford 1922; is scattered in more than a dozen papers containing Skwarral934a,1934b; Wheeler 1942; Janzen 1966, descriptions of various species, subspecies, and 1973). The landmark studies of Janzen (1966, "varieties". Two of the more comprehensive treat- 1967b) provided strong experimental evidence of ments are those of Emery (1890) and Wheeler the mutualistic nature of the Pseudomyrmex/Aca- (1942). In presenting the results of his ecological cia association, and the relationship between the studies Janzen (1966, 1967b, 1973) summarized two organisms is often cited in discussions of his understanding of acacia-ant taxonomy. Ward coevolved mutualisms (e.g. Gilbert 1983; Beattie (1989) provided a brief diagnosis of the P. 1985; Futuyma 1986). At the same time, the ferrugineus group, together with taxonomic and systematics of the acacia-ants has been neglected, nomenclatural notes on the commoner species, with the result that misidentifications and misstate- 118 JOURNAL OF HYMENOPTERA RESEARCH MATERIALS AND METHODS COLLECTIONS Material for the present study was examined in the following collections: AMNH American Museum of Natural History, New York, NY, USA ANSP Academy of Natural Sciences, Philadel- phia, PA, USA BMNH The Natural History Museum, London, U.K. CASC California Academy of Sciences, SanFran- cisco, CA, USA CHAH C.H.A. Hespenheide Collection, Univer- sity of California at Los Angeles, C A, USA CISC California Insect Survey, University of California at Berkeley, CA, USA CUIC Cornell University Insect Collection, Ithaca, NY, USA EBCC Estacion de Biologia Chamela, Jalisco, Mexico FFIC Fernando Fernandez Collection, Santa Fe de Bogota, Colombia GBFM Graham B. Fairchild Museo de Invertebrados, Universidad de Panama, Panama GCWCG.C. & J. Wheeler Collection, Silver Springs, FL, USA INBC Institute Nacional de Biodiversidad (col- lections previously held in MNCR: Museo Nacional de Costa Rica), San Jose, Costa Rica INKS Illinois Natural History Survey Insect Col- lection, Champaign, IL, USA JTLC J.T. Longino Collection, Evergreen State College, Olympia, WA, USA KSUC Kansas State University Insect Collection, Manhattan, KS, USA LACM Natural History Museum of Los Angeles County, Los Angeles, CA, USA MCSN Museo Civico di Storia Naturale, Genoa, Italy MCZC Museum of Comparative Zoology, Harvard University, Cambridge, MA, USA MHNG Museum d'Histoire Naturelle, Geneva, Switzerland MNHN Museum National d'Histoire Naturelle, Paris, France MZSP Museo de Zoologia da Universidade de Sao Paulo, Brazil NHMB Naturhistorisches Museum, Basel, Swit- zerland NHMV Naturhistorisches Museum, Vienna, Aus- tria PSWC P.S. Ward Collection, University of Cali- fornia at Davis, CA, USA SEMC Snow Entomological Museum, University of Kansas, Lawrence, KS, USA UCDC Bohart Museum of Entomology, Univer- sity of California at Davis, CA, USA UCRC UCR Entomological Collection, Univer- sity of California at Riverside, CA, USA USNM National Museum of Natural History, Washington, DC, USA WPMC W.P. MacKay Collection, El Paso, TX, USA ZMHB Zoologisches Museum, Museum fur Naturkunde der Humboldt-Universitat, Berlin, Germany ZMUC Zoologisk Museum, University of Copenhagen, Denmark ZMUH Zoologisches Institut und Zoologisches Museum der Universitat Hamburg, Ger- many ZSMC Zoologische Staatssammlung, Munich, Germany Special mention should be made of the very large and important series of Pseudomyrmex col- lected by D.H. Janzen from 1963 to 1974 and now housed in the Natural History Museum of Los Angeles County (LACM). The Janzen material includes a large number of pinned specimens (usu- ally glued to the side of the pin rather than point- mounted) and an extensive alcohol collection (partly overlapping with the pinned series but including additional accessions). Janzen's field notes per- taining to the collection of these ants have also been deposited in LACM. Obligate acacia-ants (P. ferruginem group) constitute the bulk of the col- lected material. They occur as long nest series from throughout Central America, with very useful queen- male-worker associations, making this material of inestimable value to the current revision. VOLUME 2, NUMBER 1, 1993 119 When the Janzen collection was received at LACM in 1984 most specimens had only code numbers associated with them among the pinned specimens a single individual per nest series typi- cally contained a code number, with the remaining specimens being unlabelled and in some instances difficulties arose in retrieving full data for coded specimens from Janzen' s field notes. In other cases the field notes contradicted the apparent identity or composition of a nest series. This latter problem applied mainly to pinned specimens; the alcohol material appeared to be reliably labelled or coded, i.e. the contents of the vials agreed with the field notes. Thanks to the efforts of Roy Snelling and Jack Longino, who incorporated the Janzen collec- tion into the LACM, many of these discrepancies or uncertainties were resolved, but there remains a residue of "problem material" for which collection data are lacking or ambiguous. Among the pinned specimens this comprises twelve drawers in the LACM collection which have been specifically set aside from the main collection. None of this prob- lematical material has been cited in the present study, but I have examined it and determined that no additional species are represented there. Al- though omission of this material means the poten- tial loss of some locality data, I have examined the entire alcohol collection and point-mounted repre- sentative samples so that geographic coverage re- mains extensive. The main pinned series of LACM acacia-ants, i.e. that for which accurate data labels are available, comprises 30 drawers and approxi- mately 20,000 specimens, the great majority of which were collected by Janzen. METRIC MEASUREMENTS AND INDICES All measurements were made under a Wild microscope at SOX power, using an orthogonal pair of Nikon micrometers wired to a digital readout. Measurement conventions follow those described in Ward (1985, 1989). Note that a full-face or dorsal view of the head involves positioning the posterior margin and the anterolateral margins (above the mandibular insertions) so that they lie in the same plane of view. The following measurements and indices are cited in this study (the first six measurements are taken with the head in a full-face, dorsal view): HW Head width: maximum width of head, in- cluding the eyes. VW Vertex width: width of the posterior portion of the head (vertex), measured along a line drawn through the lateral ocelli. HL Head length: midline length of head proper, from the anterior clypeal margin to the mid- point of a line drawn across the "occipital" (i.e. posterior) margin. EL Eye length: length of compound eye; note that this is measured with the head in full face, dorsal view, unlike EW(below). OD Ocellar distance: distance from the middle of the median ocellus to the midpoint of a line drawn between the lateral ocelli. OOD Oculo-ocellar distance: distance from the middle of the median ocellus to the midpoint of a line drawn across the posterior margins of the compound eyes (this distance is nega- tive in value if the posterior margin of the compound eye exceeds the median ocellus). MFC Minimum frontal carinal distance: minimum distance between the frontal carinae, poste- rior to their fusion with, or approximation to, the antennal sclerites. ASD Antennal sclerite distance: maximum dis- tance between the lateral margins of the me- dian lobes of the antennal sclerites, measured in full-face, dorsal view of the head. ASO Antennal sclerite distance, outer margins: maximum distance between the outer, lateral margins of the antennal sclerites. CLW Width of median clypeal lobe, measured between the anterolateral angles (in Pseudomyrmex satanicus and P. spinicola only; see Figs. 10, 11). MD4, MD5, MD8, MD9 A series of mandibular measurements (see Ward 1989, figure 2). MD4: distance along the basal margin of the mandible from the base to the mesial basal tooth; MD5 : length of the basal margin ; MD8 : distance along the masticatory margin from the apex to the fourth tooth, counting from the apex; MD9: length of the masticatory margin. 120 JOURNAL OF HYMENOPTERA RESEARCH EW Eye width: maximum width of compound eye, measured along its short axis in an oblique dorsolateral view of the head. SL Scape length: length of the first antennal segment, excluding the radicle. LF1 Length of first funicular segment: maximum measurable length of the first funicular seg- ment (pedicel), including its basal articula- tion in workers and queens but excluding the basal articulation in males (where it is usu- ally hidden). LF2 Length of second funicular segment: maxi- mum measurable length of the second funicular segment. LF3 Length of third funicular segment: maxi- mum measurable length of the third funicular segment. WF2 Width of second funicular segment, FL Profemur length: length of the profemur, measured along its long axis in posterior view (see Ward 1985, figure 3). FW Profemur width : maximum measurable width of the profemur, measured from the same view as FL, at right angles to the line of measurement of FL. DPL Diagonal length of the propodeum: length of the propodeum, measured in lateral view along a diagonal line drawn from the "metapleural" lobe to the metanotal groove (see Ward 1985, figure 2). BF Length of the basal (=dorsal) face of the propodeum, measured in lateral view from the metanotal groove to the point on the surface of the propodeum which is maxi- mally distant from the diagonal propodeal line. DF Length of the declivitous face of the propodeum, measured in lateral view from the "metapleural" lobe to the point on the surface of the propodeum which is maxi- mally distant from the diagonal propodeal line. MP Depth of metanotal groove ("mesopropodeal impression"), measured in lateral view from the bottom of the metanotal groove to a line drawn across the dorsal surface of the mesonotum and propodeum. PL Petiole length: length of the petiole, mea- sured in lateral view from the lateral flanges of the anterior peduncle to the posterior mar- gin of the petiole (see Ward 1985, figure 4). PND Petiolar node distance: distance from the lateral flanges of the anterior petiolar pe- duncle to the maximum height of the node, measured from the same view as PL and along the same line of measurement (see Ward 1985, figure 4). PH Petiole height: maximum height of the peti- ole, measured in lateral view at right angles to PL, but excluding the anteroventral pro- cess. PPL Postpetiole length: length of the postpetiole, measured in lateral view, from the anterior peduncle (of the postpetiole) to the point of contact with the fourth abdominal tergum, excluding the pretergite (see Ward 1985, figure 4). DPW Dorsal petiolar width: maximum width of the petiole, measured in dorsal view. MPWMinimum petiolar width: minimum width of the petiole,measured in dorsal view, anterior to DPW. PPW Dorsal postpetiolar width: maximum width of the postpetiole, measure in dorsal view. LHT Length of metatibia: maximum measurable length of metatibia, excluding the proximal part of the articulation which is received into the distal end of the metafemur (see Ward 1989, figure 5). CI Cephalic index: HW/HL OI Ocular index: EW/EL REL Relative eye length: EL/HL REL2Relative eye length, using HW: EL/HW OOI Oculo-ocellar index: OOD/OD VI Vertex width index: VW/HW FCI Frontal carinal index: MFC/HW FCI2 Frontal carinal index, using ASD: MFC/ASD ASI Antennal sclerite index: ASD/ASO SI Scape index: SL/HW SI2 Scape index, using EL: SL/EL FLI Funicular length index: (LF2 + LF3)/WF2 FI Profemur index: FW/FL PDI Propodeal index: BF/DF MPI Metanotal index: MP/HW NI Petiole node index: PND/PL VOLUME 2, NUMBER 1, 1993 121 PLI Petiole length index: PH/PL PLI2 Petiole length index, using PPL: PPL/PL PWI Petiole width index: DPW/PL PWI2 Petiole width index, using PPW: DPW/PPW PWI3 Petiole width index, using MPW: MPW/ DPW PWI4 Petiole width index, using LHT: DPW/ LHT PPWI Postpetiole width index: PPW/PPL Other Conventions Other terminology follows the usage in Ward (1989). Note that descriptions of surface sculpture and integument reflectance apply to observations made under soft light, with an opaque (Mylar) filter placed between the specimens and source of illumi- nation. Palp formula refers to the number of max- illary palp segments followed by the number of labial palp segments; 5p4,3 indicates a condition intermediate between 5,3 and 4,3, i.e. partial fusion of the fourth and fifth maxillary palp segments. Listing of synonymy under each species is re- stricted to citation of the original descriptions (with full reference given for all previously proposed junior synonyms) and new nomenclatural combi- nations. For ecologists a more useful summary of name usage is offered in Table 1 , which indicates the correspondences between the names appearing in the biological literature on acacia-ants and the currently valid scientific names. The reader will appreciate that there has been considerable misidentification of these ants. In the lists of material examined of each species, I have cited only locality and collector ("c.u." signifies collector unknown), with the source col- lections listed together at the beginning. Additional locality information is sometimes provided in square brackets, to facilitate location of the collecting site. Considerable effort was expended to determine the coordinates (latitude and longitude) of each collect- ing site, and this was then used in conjunction with the public domain software program Versamap (version 1.20) to plot the distributions of each species (Figs. 67-72). Cladistic Analysis A set of 47 characters, representing the most discrete or quantifiable differences among species or groups of species in the P. ferrugineus group, was used for phylogenetic analysis. Twenty of these characters were worker-based (11 of these manifested the same conditions in queens), 8 were queen-based, and 19 were taken from male mor- phology, primarily male genitalia. The characters and character states are as follows: 1. Worker, median clypeal lobe (0) laterally rounded or subangulate, ( 1 ) laterally with sharp angles or teeth (Figs. 10, 11). 2. Worker and queen, frontal carinae (0) rela- tively well separated, median lobes of anten- nalsclerites less exposed (Figs. 12-19, 32), (1) closely adjacent and median lobes of antennal sclerites more exposed (Figs. 10, 11, 32). 3. Worker and queen, palp formula (0) 5,3, (1) 4,3. 4. Worker, head (0) broader, relative to HL, DPL and PL, (1) narrower; see regressions of HL, DPL and PL on HW (Figs. 36-38). 5. Worker, scape (0) short, relative to HL, (1) longer; regression of SL on HL lying above that of other species. 6. Worker, conspicuous pit-like impression on midline of head (0) absent, (1) present. 7 . Worker, petiole (0) short relative to postpetiole, PLI2 0.77, (1) longer relative to postpetiole, PLI2 < 0.77. 8. Worker and queen, petiole (0) without a well differentiated anterior peduncle, i.e. weakly constricted in dorsal view and with little or no inflection of the anterior face of the petiole in lateral profile (Figs. 22, 23), (1) with a well differentiated peduncle (Figs. 20, 21, 24-29). 9. Worker and queen, petiole, dorsal view, angulate posterolateral corners (0) absent, (1) moderately developed, preceded by convex or sinuate sides (e.g. Figs, 20, 27), (2) very promi- nent, preceded by more or less straight sides (Fig. 24). 10. Worker and queen, petiole (0) shorter and higher, worker PLI 0.71, queen PLI 0.64, 122 JOURNAL OF HYMENOPTERA RESEARCH (1) more slender, worker PLI < 0.72, queen PLI < 0.64. 11. Worker, DPW relative to HW (0) narrow, (1) broader, (2) very broad; see regression of DPW on HW (Fig. 41). 12. Worker, plot of PWI3 by HW lying in (0) upper left ( 1 ) lower right (2) lower left region, of Fig. 39. 1 3 . Worker and queen, plot of PWI4 by HW lying in (0) center and lower right (1) upper left (3) lower left region, of Fig. 40. 14. Worker, postpetiole (0) broad, PPWI > 1.30, (1) narrow, PPWI 1.00-1.30. 1 5 . Worker, metatibia (0) short, relative to HL, ( 1 ) relatively long; see regression of LHT on HL (Fig. 30). 16. Worker and queen, head sculpture (0) densely punctulate, subopaque to sublucid, at least on upper third of head, (1) densely punctulate, opaque, (3) punctulate-coriarious, opaque (matte). 17. Worker and queen, propodeum, posterolat- eral portions (0) sublucid, without overlying rugulo-punctate sculpture, (1) supopaque to opaque, with rugulo-punctate sculpture. 18. Worker and queen, petiolar node (0) lacking conspicuous suberect pubescence, (1) with such pubescence. 19. Worker and queen, standing pilosity on exter- nal faces of tibiae (0) present, (1) absent. 20. Worker and queen, head and gaster (0) yel- low- to orange-brown, (1) reddish-brown to medium or dark brown, (2) very dark brown to black (excluding mandibles, clypeus and scape). 21. Queen, size (0) small, HW 0.85, (1) medium to large, HW 0.85. 22. Queen, head shape, for a given LHT (0) elon- gate, (1) less elongate, (2) broad (see Fig. 52). 23. Queen, petiole (0) short, relative to HW, PL/ HW < 0.7 1 , ( 1 ) longer, PL/HW 0.71. 24. Queen, petiole (0) short, relative to HL, (1) longer: see regression of PL on HL (Fig.46). 25. Queen, regression of PH on HW lying in (0) upper (1) middle (2) lower region, in Fig. 47. 26. Queen, petiole, dorsal view (0) narrow, rela- tive to HL, (2) broader; regression of DPW on HL lying above that of other species. 27. Queen, metatibia (0) short, relative to HL, LHT/HL < 0.62, (1) longer, LHT/HL > 0.66. 28. Queen, metatibia (0) short, relative to HW, (1) longer; see regression of LHT on HW (Fig. 31). 29. Male, head (0) narrower, CI 0.82-0.94 and HW < 0.96, (1) broader, CI 0.94 and/or HW 0.96 (regression of HL on HW lying below that of other species). 30. Male, scape index (SI) (0) 0.22-0.30, (1) 0.29- 0.35, and regression of SL on HW lying above that of other species. 3 1 . Male, scape length, relative to EL and HL (0) long, SI2 0.43-0.56, SL/HL 0.22, (1) shorter, SI2 0.33-0.43, SL/HL 0.21 (and regression of SL on HL lying below that of other species). 32. Male, compound eye length, relative to HW (0) long, REL2 0.56-0.63, (1) shorter, REL2 0.49-0.58, and regression of EL on HW lying below that of other species. 33. Male, petiole (0) less slender, PLI > 0.45, (1) more slender, PLI < 0.50, and regressions of PH and DPW on LHT lying below those of other species. 34. Male, sternite IX, posterior margin (0) con- vex, (1) with a moderate concavity, less than semicircular (Fig. 54), (2) with a deep, semi- circular concavity (Fig. 55). 35. Male, paramere, lateral view, posterodorsal extremity (0) rounded, (1) angulate or ex- panded. 36. Male, paramere, lateral view, posterodorsal extremity (0) not projecting caudad, (1) pro- jecting caudad, as in Figs. 56, 57. 37. Male, paramere, lateral view, posterodorsal extremity (0) not developed as a lobe-like protrusion, whose mesial face is a saucer-like concavity, (1) so developed (Figs. 61-66). 38. Male, paramere, lateral view, posterodorsal extremity (0) well separated from mesiodorsal lobe, (1) close to mesiodorsal lobe, enclosing a narrow space between it and the lobe (Figs. 58, 61-66). 39. Male, paramere, digitiform mesiodorsal lobe (0) absent, ( 1 ) present, slender, directed poste- VOLUME 2, NUMBER 1, 1993 123 riorly or posterodorsally (Figs. 56-60, 63-65), (2) present, stubby, directed more or less dor- sally (Figs. 61, 62). 40. Male, paramere, mesial face of posterodorsal extremity (0) simple in form, not expanded mesially, (1) expanded mesially, partly ob- scuring the mesial dorsoventral ridge in poste- rior view. 41. Male, aedeagus, posterior margin (0) entire, not medially pointed, (1) toothed, and medi- ally pointed. 42. Male, aedeagus, posterior margin (0) bent posterolaterally, (1) bent anterolaterally, (2) bent anterolaterally but with the medial point redirected posteriorly. 43. Male, aedeagus, laterally bent portion of pos- terior margin (0) continuous with the margin of the posterodorsal extremity,(l) discontinu- ous with margin of posterodorsal extremity (elevated laterally), the two connected by a gradual slope, (2) discontinuous with margin of posterodorsal extremity, elevated laterally, and separated by a trenchant rise (posterior view) from the posterodorsal extremity. 44. Male, aedeagus, plate-like expansion of posterodorsal extremity (0) absent, (1) mod- erately developed, (2) strongly developed. 45. Male, aedeagus, external face (0) without a large, central elevated area, (1) with a central elevated area, delimited posteroventrally by a weak ridge or carina, (2) with a central el- evated area, delimited posteroventrally by a strong lamellate carina. 46. Male, aedeagus, external face, afore-men- tioned carina (if present) (0) well separated from the toothed posterior margin, ( 1 ) running close to and more or less parallel with the toothed posterior margin but separated by a deep groove, (2) converging posterodorsally with the toothed posterior margin. 47. Male, aedeagus, postero ventral extremity (0) broadly rounded, (1) subangulate, (2) angulate with a tooth-like protrusion. The data set was analyzed using Farris' Hennig86 program. Characters 12, 13 and 16 were considered unordered. As an outgroup I chose Pseudomyrmex fervidus (F. Smith), a Central American species which shares a number of (mostly worker) features in common with the P.ferrugineus group: 5,3 palp formula, similar mandibular dentition, well devel- oped metanotal groove, abundant pilosity on mesosoma dorsum, relatively small eyes, and a similar habitus with respect to size and color. In a few instances the outgroup species spanned the phenotypic gap between two discrete states in the ingroup; it was then coded as unknown for that character. In addition to seeking the most parsimo- nious tree for the entire data set (rooted with the outgroup), I also compared the cladograms based on three subsets, derived from the worker, queen, and male characters sets, respectively. For this second analysis the queen character set included the eight characters assessed only in queens (2 1 -28) plus those manifested identically in workers and queens (2, 3, 8-10, 13, 16-20), for a total of 19 characters. 124 JOURNAL OF HYMENOPTERA RESEARCH 7 Figs. 1-9. Pseudomyrmex workers, lateral view of mesonotum, propodeum and petiole, with pilosity shown in outline; Figs. 4 and 5 include a frontal view of worker head. 1 , P. boopis (Costa Rica); 2, P. ita (Costa Rica); 3, P. kuenckeli (Costa Rica); 4, P. hesperius (Mexico, paratype); 5, P. opaciceps (Guatemala, paratype); 6, P. gracilis (Mexico); 7, P. nigropilosus (Costa Rica); 8, P. reconditus (Nicaragua, holotype); 9, P. simulans (Panama). VOLUME 2, NUMBER 1, 1993 125 h 1 mm Figs. 10-19. Pseudomyrmex ferrugineus group, workers, full-face dorsal (=frontal) view of head with pilosity shown in outline (except on mandibles); Fig. 19 includes a lateral view of head. 10, P. satanicus (Panama); 1 1, P. spinicola (Costa Rica); 12, P. peperi (Guatemala); 13, P. nigrocinctus (Costa Rica); 14, P. particeps (Costa Rica, holotype); 15, P. mixtecus (Mexico, holotype); 16, P.flavicomis (Nicaragua); 17, P. veneficus (Mexico); 18, P. ferrugineus (Mexico); 19, P.janzeni (Mexico, holotype). 126 JOURNAL OF HYMENOPTERA RESEARCH 1 mm Figs. 20-29. Pseudotnyrmex ferrugineus group, workers, dorsal view of petiole paired with lateral view of mesonotum, propodeum, petiole and, in Fig. 28, postpetiole. Standing pilosity shown in outline. 20, P. satanicus; 21, P. spinicola', 22, P. nigrocinctus', 23, P. particeps', 24, P. peperi; 25, P. flavicornis; 26, P. mixtecus; 27, P. ferrugineus; 28, P. veneficus', 29, P.janzeni. These are the same individuals illustrated in Figs. 10-19. VOLUME 2, NUMBER 1 , 1 993 127 30 1.2 workers -i- spinicola, satanicus D other species + 3 1" 1 1.4 queens -+ spinicola, satanicus D other species + + f V* * + + + D 1.3 * 1.1 +H ,*f **** * g \ + 1 v /r + ffS^^n 1.2 * + + +4- + +++ ++ + tfj a + + J.J. + [>. 5 + D + * n m tflja =5SEj5i n i 1.1 + - ^fl?^ 0.9 ** &L f#ftl B o n + + rft Jo b ^ qScrSS a o 1 t^ggi^cB 0.8 EUjjta-fSlrilj a "3 ftmijfiiflB3t]^^ 0.9 - ff fl 'jSSr'ffJj aa 0.7 a 0.8 - D 0.6 - 01 D .8 1 1.2 1.4 0.7 - .7 0.9 1.1 1.3 .* / 08 HL HW 32 0.7 - workers +- spinicola, satanicus D other species D 33 29 0.28 - workers -i- spinicola, northern popns. X spinicola, southern popns. D D D satanicus a 3 n jl D n D 0.27 - 0.6 - o r a ' ! B, 310 "fc ,,51*0 D ft' ' B a ^a * *^a i? 0.26 - X D + < 3 0.5 - S ^ "Jg ?|^o D * a * 0.25 - X X \ *** * " o a$8> =h a a a D a X xxx X x "x-t, 0.4 - ^S^^^a^ + + + +* 0.24 - + n a TD cPn* 1 D + + + + "*"+* + x a D ""b D 44. + +1|. + + + > + 0.23 - x + x + o a 0.3 - rjDD + + + + + >+* + + * + t x D 0.2 - + 0.22 - 4- 14-i 7 0.9 HW 1.1 1 3 0. > 0.82 -i 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 94 0.98 1 .02 1 .06 1.1 1.14 1.18 1 .22 1 .26 HW 34 1.35 - workers + spinicola, northern popns. X spinicola, southern popns. D satanicus a D 35 a- 0.78 - 0.76 - workers D + spinicola, northern popns. a D X spinicola, southern popns. D satanicus a D 1.3 - a o ; o =^ 0.74 - o 1.25 - + x 0.72 - x x + D o 0.7 - "xx + t 1.2 - x XX 0.68 - * \ a% o* D D 5^ 1.15 - x* X x + * 0.66 - x xx + 0.64 - x x x x x + x # x + + 1.1 - X + + 0.62 - X + X + 0.6 - + + 1.05 - x 0.5B - + 1 - x 0.56 - X X 95 * 0.54 - 0.52 - + O.S 4 0.98 1.02 1.06 1.1 1.14 1.18 1.22 1.26 O.S 4 0.98 1 .02 1 .06 1.1 1.14 1.18 1 .22 1 .26 HW HW 36 5 workers + peperi 37 1.05 - workers a D -i- peperi n o 1.4 - X nigrocinctus, particeps D X nigrocinctus, particeps a o aa D others i i * a a 1 - D others ^ D^D D tf * 1.3 - ^^v- 0.95 - B B ^gaB 1.2 - B "Jg." >s b^So? D 0.9 - *:*/ !^^ aaZ 0.85 - i + ^fi Wp tJ D a X * A HrJra B^ D ' v v -H-* BC Cf[ri x x ** ag<* =0 0.8 - 4 + D ggiP n n D 1 - "****** B" x4^ D "% 0.75 - x *+j< + % ^ x x^f + ^"Q D a ^rv * u Q 0.7 - |^ X cP D D 0.9 - V* x ao "*+ 0.65 - x X 0.8 - 0.6 - Figs. 30-37. Scattergram plots of various metric measurements and indices in workers and queens of the Pseudomyrmex ferrugineus group, "other species" refers to all others in the P. ferrugineus group. 128 JOURNAL OF HYMENOPTERA RESEARCH 42 44 O.BS - workers 39 . x * workers O.8 - + peperi X nigrocinctus, particeps a a 0.58 - X x 4- peperi X nigrocinctus, particeps D others O crf 0.56 - jfffe x D others 0.75 - n_^* ." 0.54 - * x x 0.7 - Hi tf n V-8 0.52 - ** D o o SB,* o* # 0.5 - x D D Q, 0.65 - + + + D nSr^Jb a aa a D D to 0.48 - TJ G SO rfl 0.6 - **>** f*? o a 3o cpogi n uSb^ o Q. 0.46 - 0.44 - GO %OH a, O B. D^ n 9-J ^ 9iP 0.55 - 0.5 - fc<* x &' :-? ff BjB'tBBo a Cf a _OrP D -* 1 a 0.42 - 0.4 - 0.38 - + + + . + + * D aDBo na .** D a a D 0.45 - ^t* D 0.36 - + * + B x *x D on 0.34 - + t* DO 0.7 0.9 1.1 1.3 0.7 0.9 1.1 1 HW HW 0.52 - ****** * 41 0.3 workers D legend as in Fig. 39 a 0.5 - * * ****** D 0.46 - Rjo 0.48 - **.r ****** a a 0.44 - * * * e a"<&> 0.46 - ****** an 'Sa 0.42 - " *' 8b "n^o^ * 0.44 - ** * o a ^ fl D 0.4 - * *J oil? W '"t a ff ft jp ?f] ^3 a a 0.38 - +r*^ a %?PJ a D 0.42 - 0.4 - X X G D rO DLJ^ Gigjfjo * 0.36 - e*f ego^ig^i 11 * D Q X x D C D ^ e T On 0.34 - * * + oj CD t>t 6nj" 1 ^ 0.38 - + 0.32 - Q o D 3ti P 0.36 - > X X x G r3feOQ a D 0.3 - *+ \ x aVe 0.34 - X x*x* X *J G^ o D G 0.28 - x^x^ aPo Q D 0.32 - QD t w 3 a B 0.26 - ^x 0.3 - workers legend as in Fig. 39 a D 0.24 - Xx G X 0.7 0.9 1.1 1.3 o.7 0.9 1.1 1 HW HW 0.5 - 0.49 - workers -I- particeps D nigrocinctus t 43 ^~* 49 - workers + particeps n nigrocinctus + 0.48 - + 0.48 - * 0.47 - * 0.47 - + 0.46 - + 0.46 - + 0.45 - 0.45 - + + + G D jj + + D 0.44 - 0.44 - G a D * a a 0.43 - + * a 0.43 - + D D D + a a 0.42 - a 03 0.42 - o a a D D 0.41 - o D 0.41 - a D D 0.4 - 0.4 - D D iii ' ' ' HL LHT 0.74 - 0.72 - 0.7 - workers + veneficus X mixtecus a flavicornis a D D aa ao a 45 *- 0.45 - 0.44 - 0.43 - workers -f- veneficus X mixtecus n flavicornis D D O.68 - o a 0.42 - D n Q D 0.66 - a a n O D "- 1 0.41 - D H D 0.64 - D 0.4 - D 0.62 - X D 0.39 - 0.6 - cP ^ a o D D.38 - tt 0.37 - X X 0.58 - x * x a 0.36 - x X 0.56 - 0.35 - x D 0.54 - + x 0.34 - x x a 0.52 - + * + + X 0.33 - D 0.5 - f + 0.32 - * ++ + + 0.48 - *+ D 0.31 - 0.3 - + 0.46 - 0.29 - * + a 0.44 - 0.42 - + X 0.28 - n 97 - x + Figs. 38-45. Scattergram plots of various metric measurements and indices in workers of the Pseudomyrmex ferrugineus group, "others" refers to all other species in the P. ferrugineus group. VOLUME 2, NUMBER 1, 1993 46' 129 48 50 52 queens + veneflcus D D 47 'Z\ queens D D + veneflcus o 0.95 - X mixtecus * a jp D O ferrugineus, flavicornis x x* x aoSjiBi 0.54 - X mixtecus x x rj ferrugineus, flavicornis x n D 'rf 1 D 0.9 - A janzeni X X OCD D D 0.52 - 4 nigrocinctus , particeps x o a a a 0.5 - & peperi D D a 0.85 - **** a a a 0.48 - * + D D _ a + * A * DD 8 0.8 - * * * A J 0.46 - * r+ * a ^o * t ** 0.44 - * * + + D D 0.75 - 9 a I ^* A A 0.7 - + 0.42 - :k* * * 0.4 - ** ** * 0.65 - ** * * 0.38 - * * : 0.6 - 55 - * 0.36 - n TA * / 0.9 1.1 1.3 1.5 0.75 0.85 0.95 1.05 1.15 HL HW . _ . ~ 0.42 - 0.41 - workers + + janzeni D Mexican ferrugineus 4^,04- 1.02 - queens -h flavicornis D D * D ferrugineus + +. 0.4 - o * a en 1 - a o + 0.98 - D 4- 0.39 - D _ 0.96 - a a a D 0.38 - + D gl 0.94 - a D o a 0.37 - D + D 0.92 - n 4- 0.36 - * Q D D * 0.9- a 0.35 - + + a 0.88 - n D J a 0.86 - o 0.34 - a D D g 0.84 - a 0.33 - A * 0.82 - 0.32 - O 0.8 - A 0.31 - 0.3 -I 4- 0.78 - n 7K 4 A* A 0.92 0.94 0.96 0.98 1 1.02 1.04 1.06 1.08 1.1 1.12 1.14 0.96 1 1.04 1.08 1.12 1.16 HW HW 0.6 - 0.59 - workers -* flavicornis P ferrugineus D Q * 3 _L 0.53 - 0.52 - + 0.58 - 4- 0.51 - * * D 0.57 - D *+ + * 0.5 - * t * , O.56 - ? Q + 0.49 - o a e 0.55 - * i 3 On D * 4-+* + 0.48 - a S D ** + 0.54 - D D D n * 0.53 - a ao B " * + _l B D B n n + * * 0.52 - tb ^ W 0.46 - i a cP D * O.51 - a o D 0.45 - DQC tD D a a 0.5 - o o D Q a O.44 - D u 0.49 - 1 a a o 0.43 - D D P S o 8 0.48 - a 0.42 - O.47 - 0.41 - workers D a 0.46 - 0.45 - a O 0.4 - -t- flavicornis D a a D ferrugineus 0.92 0.96 1 1 ' 1 1 1 1 1 1 1 1 w.j [ [ 1 1 1 1 1 1 1 1 1 1 p 1 1 1 .04 1 .08 1.12 1.16 1 .2 0.8 0.82 0.84 0.86 0.88 0.9 0.92 0.94 HW Cl n R -^ 0.82 - queens + spinicola 53 workers "x H- gracilis 0.8 - 0.78 - 0.76 - D D a X satanicus D ferrugineus complex A others D 0.75 - 0.7 - X nigropilosus \ x x x x Q opaciceps x x x x A simulans x reconditus a 0.65 - * A 0.74 - D n If f x ^x x X ** A * 0.72 - * A DD n O X X D a u + * x 5 ' 6 - A * * 0.7 - ^4ft% 83 go w^ff + * + + + + * A A A r a cD ff^ -iP 0.55 - + + * + 0.68 - A A f* * /> *\ **,** 0.66 - ** *" * + 4- 0.5 - 0.64 - D ^ * + .> + . * + *v* + 0.45 - 0.62 - + * fi 1 0.6 - A A + + 4. O.4 - a Figs. 46-53. Scattergram plots of various metric measurements and indices in Pseudomyrmex workers and queens. 46-52, P. ferrugineus group; "others" refers to all other species in the P. ferrugineus group; "P. ferrugineus complex" refers to a complex of five species: ferrugineus, flavicornis, janzeni, mixtecus and veneficus; 53, P. gracilis group. 1 30 JOURNAL OF HYMENOPTERA RESEARCH KEY TO PSEUDOMYRMEX SPECIES ASSOCIATED WITH SWOLLEN-THORN ACACIAS (BASED ON WORKERS AND QUEENS) The following key includes all species of Pseudomyrmex which have been found inhabiting swollen- thorn acacias in Mexico, Central America, or Colombia. Pseudomyrmex ants can be distinguished from others by their possession of a distinct postpetiole (i.e. "waist" consists of two nodes), well developed sting, relatively large eyes (eye length more than one-third head length), and short antennal scapes (one half head width or less). In the key below, species of Pseudomyrmex which are believed to be obligate inhabitants of acacia are in bold print. These species are typically rather aggressive (but this is not true of P. subtilissimus or P. nigropilosus), while the remaining facultative inhabitants are timid, generalist, stem-nesting Pseudomyrmex which usually occupy swollen-thorn acacias only sporadically. Couplets 11-19 cover the P. ferrugineus group, the principal group of obligate acacia-ants and the focus of this study. Taxonomic comments on the other acac/a-inhabiting species are presented in a later section of the paper (pp. 153- 162). Worker sizes exclude nanitic workers, i.e. the first-emerging miniature workers associated with colony-founding queens. 1 . Standing pilosity very sparse on the head, including the gula (underside), and on the mesosoma; 1 ,0, and 0-1 pairs of erect setae on the pronotum, mesonotum, and propodeum, respectively, of the worker 2 Standing pilosity common to abundant on most parts of the body, including the gula and mesosoma; worker usually with more than 10 standing hairs visible in outline on the mesosoma dorsum, not arranged in isolated pairs 4 2. Very small, light brown species (worker and queen HW < 0.60), with elongate head (CI < 0.66) and low, dorsally flattened petiole (PLI < 0.76) (Nicaragua, Costa Rica) subtilissimus (Emery) Larger species (worker and queen HW > 0.70), with broader head (CI > 0.70) and higher petiole (PLI > 0.80) (Figs. 1,2) 3 3. Smaller species (worker and queen HW < 1.00), with posterodorsally angulate petiole (Fig. 2) (Mexico to Colombia) ita (Forel) Larger species (worker and queen HW> 1.15), with posterodorsally rounded petiole (Fig. l)(Mexico to Ecuador, Brazil) boopis (Roger) 4. Head with scattered, fine punctulae on a smooth, shiny background; punctulae on upper third of head separated by several times their diameters or more 5 Head opaque to sublucid, more coarsely and densely punctulate, the punctulae subcontiguous on most parts of the head 6 5. Larger species (HW> 1.20), with broad head (CI 1.12) and abundant long pilosity (Fig. 3) (Mexico to Argentina, Brazil) kuenckeli (Emery) Small species (HW < 0.72), with elongate head (CI 0.80) and shorter, sparser pilosity (Fig. 4) (Mexico) hesperius, sp.nov. 6. Eyes relatively large and elongate (e.g. Fig. 5), eye length more than one-half head length (worker and queen REL 0.52-0.65); pronotum laterally submarginate; outer surfaces of tibiae usually with standing pilosity (may be very short); larger species, worker HW > 1.20; palp formula 6,4 7 Eyes smaller (Figs. 10-19), usually less than one-half head length (worker and queen REL 0.38-0.50); pronotum laterally rounded; outer surfaces of tibiae without standing pilosity; medium-sized species, worker HW < 1.28; palp formula 5,3or 4,3 (ferrugineus group) 11 7. Petiole long and slender, with a well developed anterior peduncle (worker and queen PLI 0.42-0.57) VOLUME 2, NUMBER 1 , 1 993 1 31 (Figs. 5,6) 8 Petiole less elongate, with a short anterior peduncle (PLI > 0.59) (Figs. 7-9, 53) 9 8. Head densely punctulate-coriarious, presenting a matte appearance; head and mesosoma black, with a contrastingly pale orange petiole, postpetiole, and gaster; petiole very slender, worker PLI 0.42-0.47 (Figs. 5, 53) (southern Mexico, Guatemala) opaciceps, sp. nov. Head densely punctulate but retaining a subopaque to sublucid (not matte) appearance; color variable but without the preceding pattern in Mexico or Guatemala; petiole usually less slender, worker PLI 0.46-0.57 (Figs. 6, 53) (throughout the Neotropics) gracilis (Fabricius) 9. Larger species (worker HW 1.47- 1.54, queen HW 1.66), with broad head (worker CI 1.00- 1.02, queen CI 0.92) (Nicaragua) reconditus, sp. nov. Smaller species (worker HW 1. 21-1.41, queenHW 1.15-1. 36); head more elongate (worker CI 0.84- 0.90, queen CI 0.77-0.80) 10 10. Standing pilosity short, pale and inconspicuous (Fig. 9); pronotum sharply margined laterally; petiole longer, worker PLI 0.61-0.66, queen PLI 0.63-0.68; color black (Panama) simulans Kempf Standing pilosity long and conspicuous, with long curved black setae arising from the propodeum and petiole (Fig. 7); pronotum with blunter lateral margination; petiole short and high, worker PLI 0.69- 0.77, queen PLI 0.68-0.75; color variable, usually pale or bicolored (Mexico to Costa Rica) nigropilosus (Emery) 1 1 . Median clypeal lobe of worker concave, with sharp lateral angles or teeth (Figs. 10, 1 1); legs long in relation to body size (Figs. 30, 3 1 ); larger species (worker HW > 0.92, worker LHT > 0.88, queen HL > 1.40, queen LHT > 1.05); frontal carinae closely contiguous, worker FCI2 0.24-0.42 (Fig. 32); propodeum punctulate to coriarious-imbricate, posterolateral portions sublucid with little or no overlying, coarse, rugulo-punctate sculpture 12 Median clypeal lobe of worker laterally rounded or subangulate (without sharp angles or teeth) (Figs. 12-19); legs shorter in relation to body size (Figs . 30, 3 1 ); size variable but if as large as the preceding (worker HW > 0.92, etc.) then frontal carinae relatively well separated, worker FCI2 > 0.43 (Fig. 32), and posterolateral portions of propodeum opaque to subopaque, overlain by coarse (although often weak and ill-defined) rugulo-punctate sculpture 13 1 2. Larger species (worker HW > 1 .09, queen HW > 1 .20); head broader, its posterior margin straight and rounding rather sharply into the sides (Figs. 10, 34); median clypeal lobe of worker longer and narrower (Fig. 33); worker with a conspicuous, pit-like impression on midline of head, anterior to the median ocellus; palp formula 4,3 (Panama) satanicus (Wheeler) Smaller species (worker HW 0.94-1. 15, queenHW 0.94 - 1.14), with head a little less broad and its posterior margin rounding more gently into the sides (Figs. 10, 34); median clypeal lobe of worker notably shorter and broader (Fig. 33); worker usually lacking a pit-like impression on mid-line of head; palp formula almost invariably 5,3, rarely 5p4,3 (Honduras to Colombia spinicola (Emery) 13. Smaller species (worker HW 0.74-0.90, queen HW 0.76-0.85); head, propodeum, and petiole more elongate, for a given head width (Figs. 36-38) 14 Larger species (worker HW 0. 85- 1 .2 1 , queen HW 0. 84- 1.19); head, propodeum, and petiole shorter, for a given head width (Figs. 36-38) 16 14. Petiole and postpetiole very broad (worker PWI 0.63-0.75, worker PWI3 0.33-0.46, worker PPWI 1.41-1.83; queen PWI2 0.69-0.78) (Figs. 40, 41), the petiolar node with conspicuous posterolateral angles, in dorsal view (Fig. 24); head very finely and densely punctulate-coriarious, presenting a matte (opaque) appearance; palp formula 4,3 (Mexico to Nicaragua) peperi (Forel) Petiole and postpetiole relatively narrow (worker PWI 0.49-0.61 , worker PWI3 0.50-0.61, worker PPWI 1 .03- 1 .30; queen PWI2 0.57-0.63), the petiolar node without conspicuous posterolateral angles 1 32 JOURNAL OF HYMENOPTERA RESEARCH (Figs. 22,23); head densely punctulate, sublucid to subopaque, but without a matte appearance; palp formula 5,3 15 15. Workers and queens light orange-brown, with a fuscous patch on anterior third of abdominal tergite IV (first gastric tergite); eyes relatively short (worker EL/LHT 0.56-0.61, queen REL2 0.58-0.66) (Figs. 13, 42, 43); queen head less elongate (queen CI 0.67-0.72) (Guatemala to Costa Rica) nigrocinctus (Emery) Workers and queens entirely dark brown; eyes longer (worker EL/LHT 0.59-0.64, queen REL2 0.69- 0.70) (Figs. 14, 42, 43); queen head more elongate (CI 0.61, in the two known specimens) (Costa Rica) particeps, sp. nov. 16. Small species (worker HW 0.85-0.95, queen HW 0.84-0.96) with head, gaster, and at least part of mesosoma very dark brown to black; body pubescence dense, decumbent to suberect, and conspicu- ous, especially on the petiolar node (Fig. 28); standing pilosity often (not always) sparse; head weakly shining (western Mexico) veneficus (Wheeler) Body pubescence dense but predominantly appressed, petiolar node without conspicuous suberect pubescence; usually larger (worker HW 0.89-1.21, queen HW 0.96-1.19) with more conspicuous standing pilosity; color and head sculpture variable 17 17. Head and gaster (typically also mesosoma) very dark brown to black; head densely punctulate and opaque 18 Body lighter in color: light orange-brown to medium brown, rarely dark brown; head at least weakly sublucid between ocelli and upper margin of the compound eye 19 18. Smaller species, worker HW 0.89-1.03, queen HW 0.96-1.01; petiole relatively longer and higher (Figs. 44-47) (southern Mexico) mixtecus, sp. nov. Larger species, worker HW 0.99-1.21, queen HW > 1.10; petiole relatively shorter and lower (Figs. 44-47) (Guatemala to Costa Rica) .flavicornis (F. Smith) 19. Head and mesosoma light orange-brown, the gaster similar or slightly darker; underside of head (gula) with conspicuous suberect pubescence (Fig. 19); profile of worker mesosoma as in Fig. 29; smaller species (worker HW 0.93-1.03, queen HW 0.96-1.00) with shorter, higher petiole (Figs. 46-49) (western Mexico) .janzeni, sp. nov. Gaster (and usually head) medium to dark brown, mesosoma variable; gular pubescence usually more appressed and inconspicuous; in profile worker mesosoma usually with basal face rounding more gradually into declivitous face (Fig. 27); size variable but larger on average (worker HW 0.92- 1 . 15,queen HW 0.92-1 . 12), with longer and lower petiole (Figs. 46-49) (eastern and southern Mexico to Honduras) .ferrugineus (F. Smith) KEY TO MALES OF THE OBLIGATE ACACIA-ANTS, PSEUDOMYRMEX FERRUGINEUS GROUP Although isolated acacia-ant males are unlikely to be encountered, the following key is offered as a supplement for determination of species in the P. ferrugineus group. It can be used to confirm worker- or queen-based identifications, but some couplets require examination of the male genitalia. 1 . Posterior margin of subgenital plate (sternite IX) with a shallow (less than semicircular) concavity (Fig. 54); scape short, SI2 0.33-0.43, SL/HL 0.21 2 Posterior margin of subgenital plate (sternite IX) with a deep, semicircular concavity (Fig. 55); scape longer, SI2 0.43-0.56, SL/HL 0.22 3 2. Paramere, in lateral view, with a slender finger-like mediodorsal lobe and angulate posteroventral corner (Fig. 57) particeps Paramere, in lateral view, with a stubbier mediodorsal lobe and more gently rounded posteroventral VOLUME 2, NUMBER 1, 1993 133 corner (Fig. 56) nigrocinctus 3. Scape and compound eye longer, relative to HW (SI 0.29-0.35; REL2 0.56-0.62 (n=6)); head narrower, CI 0.82-0.94, HW 0.81-0.95; lateral view of paramere as in Figs. 58a, 58b peperi Scape and compound eye shorter (SI 0.22-0.30, REL2 0.49-0.58); head broader, CI 0.94 and/or HW 0.96; lateral view of paramere not as in Figs. 58a, 58b 4 4. Paramere, in lateral view, with posterodorsal corner well separated from mediodorsal lobe (Figs. 59- 60) 5 Paramere, in lateral view, with posterodorsal corner bent upward and enclosing a space between itself and the mediodorsal lobe which is subequal to the area of the latter (Figs. 61-65) 6 5. Lateral view of paramere as in Figs. 59a and 59b: mediodorsal lobe relatively broad and partly enclosing a space between itself and the posterodorsal corner; larger species, HW 1.06-1.09 (n=5) satanicus Paramere typically as in Fig. 60a, with mediodorsal lobe more slender and more distant from posterodorsal corner (Fig. 60b depicts a less typical male, from Colombia); smaller species, HW 0.92- 1.05 (n=12) spinicola 6. Mediodorsal lobe of paramere stout, directed more or less dorsally (Figs. 61, 62) 7 Mediodorsal lobe of paramere more slender and directed posterodorsally (Figs. 63-65) 8 7. Body pubescence dense and conspicuous, suberect on dorsum of head, propodeum and petiole; smaller species, HW 0.79-0.88 (n=7) veneficus Body pubescence less dense and less conspicuous, predominantly appressed or decumbent on the propodeum and petiole; larger species, HW 0.88-0.97 (n=6) mixtecus 8. Smaller species, HW 0.93-0.96 (n=6) janzeni Larger species, HW 0.99-1.19 (n=22) .ferrugineus andflavicornis PSEUDOMYRMEX FERRUGINEUS GROUP Introduction Worker, diagnosis. Medium sized species (HW 0.74- 1 .26, HL 0.86- 1 .42); head varying from mod- erately elongate to rather broad (CI 0.75-0.97), with relatively short eyes (REL 0.39-0.50, REL2 0.45- 0.62) (Figs. 10-19). Masticatory margin of man- dible with 6, rarely 7, teeth, MD8/MD9 0.70; mesial tooth on basal margin notably closer to apicobasal angle than to proximal tooth, MD4/ MD5 0.74. Palp formula 5,3, reduced to 4,3 in two species. Anterior margin of median clypeal lobe somewhat blunt-edged, in dorsal view convex, straight or concave, laterally rounded or with sharp angles. Frontal carinae separated by about basal scape width in most species but more closely con- tiguous in two (FCI 0.03-0. 10, FCI2 0.24-0.75, ASI 0.52-0.73), fusing anterolaterally with antennal sclerites. Funicular segments II and III about as broad as long (FLI 1 .46-2.45). Profemur slender (FI 0.35-0.41). Pronotum laterally rounded. Metanotal groove well marked (MPI 0.04-0.09). Basal and declivitous faces of propodeum moderately well differentiated and subequal in length (PDI 0.94- 1.30), in profile the juncture between the two subangulate or gently rounded (Figs. 20-29). Peti- ole relatively long (PL/HL 0.44-0.63), always much longer than high or wide (PLI 0.47-0.7 1 , PWI 0.46- 0.75), small anteroventral tooth present; in two species anterior peduncle of petiole weakly differ- entiated and posterolateral corners of petiolar node not expanded (these are presumably the plesiomorphic conditions in the group), in other species petiole with distinct anterior peduncle and with expanded, (sub)angulate posterolateral cor- ners. Postpetiole broader than long (PPWI 1.03- 1.85), with small anteroventral tooth. Body sculp- ture varying from densely punctulate or punctulate- coriarious to coriarious-imbricate, the integument sublucid to opaque; dorsum of head never with extensive smooth, shiny interspaces (punctulae usually separated by their diameters or less); propodeum of some species overlain by a coarser but weak rugulo-punctate sculpture. Standing pi- losity common, present on the scapes, head, entire mesosoma dorsum (10 or more standing hairs vis- ible in profile), petiole, postpetiole and gaster, 134 JOURNAL OF HYMENOPTERA RESEARCH 54 57 58b 60b 61a 63b 62 1 mm 64b Figs. 54-66. Pseudomyrmexferrugineus group, male terminalia. Figs. 54-55: sternite IX; Figs. 56-65 : left paramere, lateral view, caudal end to right; Fig. 66: left paramere, mesial view. 54, P. particeps (Rincon, Costa Rica); 55, P. mixtecus (near Tehuantepec, Mexico); 56, P. nigrocinctus (lOmi. NW Liberia, Costa Rica); 57, P. particeps (Rincon, Costa Rica); 58, P. peperi (58a: 3km ENE Chiapa de Corzo, Mexico; 58b: Nueva Ocotepeque, Honduras); 59, P. satanicus (59a: 3mi. SW Gatun Dam, Panama; 59b: Marajal, Panama); 60, P. spinicola (60a: Madden Dam, Panama; 60b: Aracataca, Colombia); 61, P. mixtecus(61&: 57. 8mi. S Chilpancingo, Mexico; 61b: near Tehuantepec, Mexico); 62, P. veneficus (5km E Chamela, Mexico); 63, P.flavicornis (63a: Rio Oro, Costa Rica; 63b: 3.6mi. W Choluteca, Honduras); 64, P. janzeni (64a: 60mi. SE Acaponeta, Mexico; 64b: 4mi. E San Bias, Mexico); 65, P. ferrugineus (65a: Escuintla-Cd. Guatemala, Guatemala; 65b: 10.8mi S Pichucalco, Mexico); 66, P. ferrugineus (10.8mi S Pichucalco, Mexico). VOLUME 2, NUMBER 1, 1993 135 absent from the extensor faces of tibiae. Appressed pubescence dense on most of body, including head and abdominal tergite IV. Color varying from light yellow- or orange-brown to black. Queen diagnosis. Similar to worker except for caste-specific differences. Larger in size (HW 0.76- 1.36, HL 1.05-1.81), head more elongate (CI 0.60- 0.80). Ocular indices differing slightly: REL 0.38- 0.48, REL2 0.51-0.70. Median clypeal lobe nar- rower and more protruding, anterior margin convex or straight, laterally rounded or subangulate. Peti- ole and postpetiole generally more slender (PL/HL 0.57-0.72, PLI 0.43-0.63, PWI 0.47-0.67, PPWI 1.06-1.50). Forewing with 2 cubital cells. Male, diagnosis. Head varying from longer than broad to slightly broader than long (CI 0.82- 1.04 in a sample of 70 males belonging to all species); compound eye large, prominent (REL2 0.49-0.62). Mandibles with 8+ teeth or denticles on masticatory margin. Palp formula as in females, but somewhat more variable (males with 5p4,3 commoner than in workers or queens). Surface of median clypeal lobe convex, its anterior margin subtriangular in shape (dorsal view) with sides converging medially to a rounded point. Petiole and postpetiole more slender than in workers (PLI 0.40-0.55, PWI 0.35-0.51) and simpler in shape. Posterolateral corners of sternites IV- VIII not nota- bly protruding ventrally. Subgenital plate (sternite IX) with a conspicuous posteromedial concavity (Figs. 54, 55). Posterior margin of pygidium (terg- ite VIII) convex, directed posteroventrally. Paramere with several characteristic features: a finger-like, posterodorsally directed mediodorsal lobe; angulate or expanded posterodorsal extrem- ity; and mesial dorsoventral ridge which joins the mediodorsal lobe posteriorly. Aedeagus with ex- panded posterodorsal corner, a medial protrusion on the posterior margin,numerous small teeth (15+) on the posterior margin, and on the outer face a raised ridge curving posterodorsally from a basal origin. Comments. Workers and queens of the P. ferrugineus group can be distinguished from all other Pseudomyrmex by their possession of the following combination of traits: mandibles with 6- 7 teeth; palp formula 5,3 or 4,3; standing pilosity common on mesosoma dorsum but absent from external faces of tibiae; worker metanotal groove conspicuously impressed; and head densely punctulate, sublucid to opaque. The relatively short eyes (worker REL 0.50, queen REL 0.48) and slender petiole (worker PLI 0.71, queen PLI 0.63) are also characteristic. Among the eight other major species groups of Pseudomyrmex (diagnosed in Ward, 1 989) only the P. viduus and P. oculatus groups have workers and queens approach- ing these conditions. Those of the P. viduus group have a shinier head, a shorter and more robust petiole (worker PLI > 0.70, worker PWI > 0.70), and standing pilosity on the tibiae (reduced in one species), while workers and queens of the P. oculatus group have a palp formula of 6,3 (reduced to 5,3 only in smallest species with worker and queen HW < 0.67), tectiform and sharp-edged median clypeal lobe with a broadly convex margin (dorsal view), elongate eyes (worker REL 0.48-0.6 1 , worker REL2 0.62-0.86, queen REL 0.43-0.57, queen REL2 0.68- 0.89), and short petiole (worker PLI 0.67-1.06, queen PLI 0.57-0.94). Among taxonomically iso- lated species not belonging to one of the major species groups, P.fervidus (F. Smith) bears perhaps the closest phenetic resemblance to the P. ferrugineus group, but its workers and queens can be distinguished by their shinier and less densely punctulate head, shorter petiole (worker PLI 0.71- 0.76, worker PL/HL 0.41-0.44 (n=9); queen PLI 0.65, queenPL/HL 0.49), and standing pilosity on the outer faces of the tibiae. In addition the queens of P. fervidus have a distinctive, pointed median clypeal lobe not seen in P. ferrugineus group queens. Males of the Pseudomyrmex ferrugineus group can be characterized by their palp formula, medi- ally subangulate clypeal lobe, emarginate subgenital plate, configuration of the paramere, and shape of the aedaegus. They are approached most closely in this combination of traits by males of P. haytianus (Forel) and two undescribed Central American species (P. sp. PSW-02 and P. sp. PSW-54) al- though, curiously, the workers and queens of those species do not bear a close resemblance to those of the P. ferrugineus group. All species in the P. ferrugineus group are obligate inhabitants of Central American swollen- thorn acacias, a biological trait not characterizing any other species group of Pseudomyrmex, al- 136 JOURNAL OF HYMENOPTERA RESEARCH though a few species in the otherwise quite differ- ent P. gracilis group and one species in the P. subtilissimus group have independently developed an obligate association with the acacias. Distribution. Members of the P. ferrugineus group are found from eastern (San Luis Potosi, Tamaulipas) and western (Sinaloa) Mexico south through Central America to northern Colombia (Fig. 67). Although no single species spans the entire range of the group, their collective distribu- tion is virtually identical to that of the swollen- thorn acacias (compare Fig. 67 with Janzen 1974:3). Synonymic List of Species P. ferrugineus (F. Smith 1877) Mexico to Hondu- ras = P.fulvescens (Emery 1890) (Ward 1989) = P. canescens (Wasmann 1915) (Ward 1989) = P. wasmanni (Wheeler 1921) (replacement name for canescens) = P. bequaerti (Wheeler 1942) (Ward 1989) = P. saffordi (Wheeler 1942) (Ward 1989) = P. vesanus (Wheeler 1942) (Ward 1989) = P. bequaerti (Enzmann 1945) (Brown 1949) = P. honduranus (Enzmann 1945) (Ward 1989) P.flavicornis (F. Smith 1877) Guatemala to Costa Rica = P. belti (Emery 1890) (Ward 1989) = P. obnubilus (Menozzi 1927a) (Ward 1989) = P.fellosus (Wheeler 1942) (Ward 1989) P. janzeni Ward, sp. nov. Mexico P. mixtecus Ward, sp. nov. Mexico P. nigrocinctus (Emery 1890) Guatemala to Costa Rica = P. alfari (Forel 1906) syn. nov. = P. bicinctus (Santschi 1922) syn. nov. = P. peltatus (Menozzi 1927) syn. nov. P. particeps Ward, sp. nov. Costa Rica P. peperi (Forel 1913) Mexico to Nicaragua = P. convarians (Forel 1913) (Ward 1989) = P. saffordi (Enzmann 1945) (Ward 1989) P. spinicola (Emery 1890) Honduras to Colombia = P. atrox (Forel 1912) syn. nov. = P. gaigei (Forel 1914) syn. nov. = P. infernalis (Wheeler 1942) syn. nov. = P. scelerosus (Wheeler 1942) syn. nov. = P. infernalis (Enzmann 1945) (Brown 1949) = P. scelerosus (Enzmann 1945) (Brown 1949) P. satanicus (Wheeler 1942) Panama P. veneficus (Wheeler 1942) Mexico = P. venificus (Enzmann 1945) (Brown 1949) SPECIES ACCOUNTS Pseudomyrmex ferrugineus (F. Smith 1877) (Figs. 18,27,65,66,70) Pseudomyrma ferrugineaF. Smith 1877:64. Lec- totype worker, Mexico (BMNH) [Examined]. Pseudomyrma beltiracefulvescens Emery 1 890:64. Lectotype worker, Guatemala (Beccari) (MCSN) [Examined] [Synonymy by Ward 1989:437; see also Janzen 1967b:391]. Pseudomyrma canescens Wasmann 1915:321. Syntype workers, Tampico, Mexico (Brakhoven) (MCSN, MCZC) [Examined] [Synonymy by Ward 1989:437]. Pseudomyrma wasmanni Wheeler 1921:92. Re- placement name, now unnecessary, for P. canescens Wasmann 1915 (nee F. Smith 1877). Pseudomyrma belti subsp. bequaerti Wheeler 1942:164. Lectotype worker, Puerto Castilla, Honduras (J. Bequaert) (MCZC) [Examined] [Synonymy by Ward 1989:437]. Pseudomyrma belti subsp. saffordi Wheeler 1942:162. Lectotype worker, Chicoasen, Chiapas, Mexico (G. N. Collins) (MCZC) [Ex- amined] [Synonymy by Ward 1989:437]. Pseudomyrma belti subsp. vesana Wheeler 1942:163. Holotype (unique syntype) worker, Cordoba, Mexico (F. Knab) (MCZC) [Exam- ined] [Synonymy by Ward 1989:437]. Pseudomyrma belti subsp. bequaerti Enzmann 1945:80. Syntype workers, Puerto Castilla, Honduras (J. Bequaert) (MCZC) [Examined] [Objective synonym of P. belti bequaerti Wheeler; Brown 1949:42]. Pseudomyrma kuenckeli var. hondurana Enzmann 1945:87. Lectotype worker, Honduras (Bates) (MCZC) [Examined] [Synonymy by Ward 1989:437]. Pseudomyrmex ferruginea [sic] (F. Smith); Janzen 1966:252. Pseudomyrmex ferrugineus (F. Smith); Kempf VOLUME 2, NUMBER 1, 1993 137 S cc"g 2 S U -3 O g S. c?- 1-1 D- a^ Jl =3 SiS.* S 3"a^ M w t! oi cd a p, &1 Pi U "1 ^ -S J is ^ ^ ^ a; n > ~O o 1 'G "2 ~*3 C "S E" "" 1? ~^j ~^J "^ i) 1-0 -0 -OS" |o g | & ^ ^ ex c: & & ."> a "^ 3 "g" > ~~ -1J - ^ ^ 3 S ti ji 5 O 60 i^, <u ti CL 2 -S "^ ^ CLO u M^-S^CL " ^2 io io " SO ^? ^ -& | ' w^Me" 1 M ' L) 8 S s = "8 " -a _S c o"o ou o"o"^"o"o"o -g^ ^ i s |l| 1 * -i .i ;s -i -i ^ -S .i .i .i .i .i * J C u H. g J- OJ -^ s s s o -a c | "^ di g u 'C g rt c " ^ o, a i- ^^. -o "vj i- 03 w i_ T3 u O 4J 3 ^^ S g ,3 J3 aj ex u M ti ^ *? s ^ ^-^' " X OJ 1J _C Ji S J 3 Q. V | u ^ y * re ^ j~ cj > ,0 a a -o .3 1 ^t S i [_2 ^ 2 "o """ 5 ^8 u u " ^3 .,--.-. o o * 3 "5 OJD s -^ rt -^-~^ febba"S 1 1 S w ^i, -O -C f> -Q S p 03 oc - o J 3 o -g op ^ ^_^ HJ - _, .| g o rt CO | | d 1 ' ^ cs a a a a ^ 'D a O U U O 2 S sees s ua ^ ,- vj y "C 'G 'o 'G 2 'G 2 . . <u _d ""D* '5 oo oo a oo ^ y ~ '" ^ 5 a! so bo bo bo be ' ' bo - ^ ^ <ii >^ LT] ^ S i SCCC-CX, -ex 55 fill _g _g ^ 2 "5- ch '- ZS S ^S --^ ^~- ti S o S t^ t^ | S ^ ^ 03 C C rt C3 c > O ^ " o ' ' ' ^^~ o * a 2 t O U -M *U *U -^ "iH - M -. -^ .^ P 3 R -^ S *^ 4 ~ l U rS i 2 1 55 1 511 1 3 flj ^ -rt & ~, ^~~ ' | t "i ? t^ t! 'Zr _y o - 'S a ex S 'g- _O jH C jr< ^ V- Qj j^ "^ r oi) "^ 'H' s w "TH" ^ . s ^-^ --* "^ TT ^ .S ^ V4- c3 *-> cfl S ^~u *- S re^ 1 s 1 i 1 | ex s^cx 3 gs^gag ex" " ~ S " S S E~^.|-S^ '-S, S '-2. ^~> S ^* c ^ -S cm J- " "So P ^ -o -J- t ^ ~3 ~O to *^ ^ ~^ 'r a a S c , ^o^o^-2-o -o-c-o-o_o-S<-^'^ 3 cj __rt ' "3 p, ^ np U "> ^ C C 1> QJ 03 c "S S -S T3 S a ^ i g ?~ ~ &D H .a C ^ Q 'Q CT S r~ ^ . " "" CO O ^- O c"3 Os ^~L 'r?- ^^ <u ^~ cc u^ -^- a 2 g; i"Si ^ 03 ^ ^ 2 C ^ 2 S^ 5^5;$ S F rfp S -g c C OT'~-22 ^S 2^2 2 S^" 3 ^6 "111 j a) sj .2 a -s S 3 aj 3 3 r2 S S J3 <, i c r" r 1 W "i^Is"^^ ~ ^2 = iTsi 11 1 i K^' - S -S g c? ^^ S*^ c SETT Zeals* 5SJ5 Sc& A ^,2 : ~J <U 3 ZS 3 "o C X *tj S & S E S; ~ : c; -a S cxi ^ e ^ o oC ^ sO T3 ON aj c a3 OJ -T3 s s ^ O r-i ex g A V >, -Q ^j >. 2 g -a -S ^ n ti CO Ji ? <U OJ tu o - 138 JOURNAL OF HYMENOPTERA RESEARCH 1972:218. Worker measurements (n = 69). HL 0.99- 1.33, HW 0.92-1.15, MFC 0.054-0.108, CI 0.81-0.94, REL 0.42-0.48, REL2 0.48-0.54, OOI 1.39-3.16, VI 0.60-0.78, FCI 0.054-0.101, SI 0.41-0.46, SI2 0.79-0.91, NI 0.61-0.72, PLI 0.54-0.69, PWI 0.56- 0.73, PPWI 1.34-1.70. Worker diagnosis. Medium-sized species (HW > 0.91; LHT 0.75-1.06) with broad head (CI > 0.80); anterior margin of median clypeal lobe straight or weakly concave, rounded laterally; palp formula 5,3; frontal carinae well separated (FCI > 0.05) and median lobe of antennal sclerite not strongly ex- posed (FCI2 0.45-0.69); mesosomal profile typi- cally as in Fig. 27, with mesonotum notably in- clined and with basal face of propodeum rounding gradually into declivitous face, but deviations from this pattern occur; petiole relatively short, high and wide (see relevant metrics: PLI, PWI), with a dis- tinct anterior peduncle (PWI3 0.36-0.50); postero- lateral angles of petiole moderately developed but not as pronounced as in P. peperi (compare Figs. 24 and 27) ; postpetiole broad. Head densely punctulate, predominantly opaque or subopaque but at least weakly shining on upper third of head between ocelli and compound eye; mesosoma punctulate to punctulate-coriarious, subopaque to sublucid; pos- terior portions of propodeum opaque to subopaque and usually overlain by larger but weak, irregular punctures or rugulae. Petiole, postpetiole and gaster with fine piligerous punctures, sublucid. Standing pilosity common; pubescence dense but fine and appressed on most surfaces. Color variable, from light reddish- or yellowish-brown to very dark brown, gaster (and usually head) somewhat darker than the mesosoma; mandibles, scapes, fronto- clypeal complex, and apices of legs usually lighter. Comments. Workers and queens of P. ferrugineus can be recognized by features of head morphology (laterally rounded median clypeal lobe, well separated frontal carinae and correspondingly limited exposure of the median lobes of the anten- nal sclerites, and moderately broad worker head; see Fig. 1 8), head sculpture (densely punctulate and (sub)opaque, but weakly shining on upper third of head between the ocelli and compound eye), and coloration (variably brown, not black or orange- brown). This species is most likely to be confused with the allopatric P. janzeni and the partly sympa- tric P.flavicornis. See under those species for more specific discussion. Distribution and biology. P. ferrugineus is distributed from eastern and southern Mexico to El Salvador and Honduras (Fig. 70). It is a common species and colonies have been recorded from all swollen-thorn acacia species growing within its range, i.e. Acacia chiapensis, A. collinsii, A. cookii, A. cornigera, A. gentlei, A. globulifera, A. hindsii, A. janzenii, A. mayana and A. sphaerocephala. P. ferrugineus is usually monogynous (Janzen 1967b, 1973) but a few alcohol nest series from Guate- mala, belonging to apparently mature colonies (as judged by the presence of alates), contained more than one dealate queen. Janzen (1966, 1967b) conducted a massive experimental study of the interaction between P. ferrugineus and Acacia cornigera in Mexico, and the results of these ex- periments, together with copious additional obser- vations by Janzen, showed conclusively that the ants protect the acacia from herbivores and compet- ing plants (especially vines). P. ferrugineus was also the subject of a study on kinship and nestmate recognition among workers (Mintzer 1982; Mintzer et al. 1985) which demonstrated a worker-based and probably inherited component to colony odor. Statements about the biology of "P. ferruginea" from regions south of El Salvador and Honduras (e.g. Janzen 1983) refer to a different species, P. spinicola. Material examined (AMNH, BMNH, CASC, CHAH, CISC, CUIC, INHS, LACM, MCSN, MCZC, MHNG, MNHN, MZSP, NHMV, PSWC, SEMC, UCDC, USNM, WPMC). BEUZEBelize: 2.2mi W Belize, rd.to Chetumal (D.HJanzen); 3.8mi NW Belize, rd.to Chetumal (D.H.Janzen); 4.9mi SW Belize, rd.to Cayo (D.HJanzen); Belize (Baker; c.u.); Manatee [River] (J.D.Johnson; c.u.); nr. Belize (N.L.H.Krauss); Cayo: 36.1mi SW Belize (D.H.Janzen); 36.1mi [S]W Belize (U.Kansas Mex.Exped.); El Cayo [=San Ignacio] (N.L.H.Krauss); Pine Mtn. Ridge, Mecal R., 415m (G.D.Alpert); San Ignacio (S .E.Schoenig) ; Corozal: 1 3 .5mi S Sta.Elena (Lou- isville) (D.H.Janzen); 15mi S Sta.Elena (Louis- ville) (D.H.Janzen); Orange Walk: 5mi SE Orange VOLUME 2, NUMBER 1, 1993 139 Walk, rd.to Belize (D.H.Janzen); Toledo: Punta Gorda (H.Broomfield). EL SALVADOR Chalatenango: 4.7mi NW La Palma, 880m (D.H.Janzen); 5.5mi SE La Palma, 11 30m (D.H.Janzen). GUATEMALA A Ita Verapaz'. San Joaquin, nr. San Cristobal Verapaz, 1080m (D.H.Janzen); Trece Aguas (Schwarz & Barber); Chimaltenango: Yepocapa (H.T.Dalmat); Coatepeque: 2mi W Coatepeque (D.H.Janzen); ElProgreso: 4.9mi SW Sanarate, 780m (D.H.Jan/en); Escuintla: 1.7mi S Escuintla, 370m [on CA-2] (D.H.Janzen); 12.6mi NE Escuintla, rd. to Cd. Guatemala, 1120m (D.H.Janzen); 15km E Escuintla [on CA-9] (D.H.Janzen); 3mi N Escuintla [on CA-9] (D.H.Janzen); 3mi S Escuintla [on CA-9] (D.H.Janzen); 43km S Cd. Guatemala [=15km E Escuintla] (D.H.Janzen); 6.8mi S Escuintla, 280m [on CA-2] (D.H.Janzen); 8.3mi N Escuintla [on CA-9] (D.H.Janzen); 9. 2mi N Escuintla, 900m [on CA-9] (D.H.Janzen); Escuintla (W.M.Wheeler); Pantaleon (Champion); Guatemala: 16.2mi NE Cd.Guatemala (D.H.Janzen); 19kmS Cd.Guatemala [on CA-9] (D.H.Janzen); 20mi SE Cd.Guatemala, 1060m [on CA-1] (D.H.Janzen); 6.2mi NE Cd.Guatemala, 700m (D.H.Janzen); 7.9mi S Cd. Guatemala, 1360m [on CA-9] (D.H.Janzen); 8. Imi NE Cd. Guatemala, 850m (D.H.Janzen); Cd. Gua- temala (Champion); Cd. Guatemala, 980m (D.H.Janzen); Escuintla-Cd.Guatemala [=19km S Cd. Guatemala] (D.H.Janzen); Huehuetenango: 12.4mi SE Mex. border at Cd. Cuauhtemoc (D.H.Janzen); 12.5mi SE Mex.border at Cd. Cuauhtemoc (D.H.Janzen); 37.6mi NW Huehuetenango, 900m (D.H.Janzen); 7. Imi SE Mex.border at Cd. Cuauhtemoc (D.H.Janzen); 9.3mi SE Mex.border at Cd. Cuauhtemoc (D.H.Janzen); Izabal: l.lmi NE Quirigua, 120m (D.H.Janzen); 2. Imi SW Morales, 50m (D.H.Janzen); Lago Izabal, 1km NE El Estor [= 1.5km NE El Estor] (D.H.Janzen); Los Amates (Kellerman); Murciellago (D.H.Janzen); Quirigua (W.M.Wheeler); Jutiapa: 6.7mi N San Cristobal, 280m (D.H.Janzen); 6.9mi N San Cristobal, 290m (D.H.Janzen); 9miSW Jutiapa, 950m (D.H.Janzen); Peten: 70km NW Tikal (W.R.Tschinkel); Tikal (T.H.Hubbell; N.L.H.Krauss; W.R.Tschinkel); Quezaltenango: 7.2mi NE San Felipe, on Retalhuleu-QuezaltenangoRd. (D.H.Janzen); 7.5mi NE San Felipe, on Retalhuleu-Quezaltenango Rd. (D.H.Janzen); Retalhuleu: 1.3mi E Champerico (D.H.Janzen); 2mi NE Champerico (D.H.Janzen); 5mi W Retalhuleu (D.H.Janzen); 5mi W Retalhuleu, Hwy. CA-2, at Rio Nil (D.H.Janzen); Champerico (Baker; F.Knab); Puenta Samala, 3.8mi NE San Felipe (D.H.Janzen); Retalhuleu (Stoll); SantaRosa: 25mi SE Escuintla, 200m [on CA-2] (D.H.Janzen); Solola: "Pacific slope", 3000ft. (c.u.); Suchitepequez: Patulul (W.M.Wheeler); Zacapa: lOmi SW El Lobo, 170m [on CA-9] [=9.2mi NE Piedras de Afilar] (D.H.Janzen); 2.6mi SW El Lobo, 100m [on CA-9] [=16.6mi NE Piedras de Afilar] (D.H.Janzen); 8. Imi SWLos Amates, 160m [on CA-9] [=8.0mi NE El Lobo] (D.H.Janzen); 8.2mi NE Piedras de Afilar, 160m [on CA-9] [=12.2mi NE Rio Hondo] (D.H.Janzen); dept. unknown: "Guatemala" (Beccari); Concepcion, 1400ft. (C.N.Ainslie); Mimosa, "Cocepcion" [Concepcion] (C.N.Ainslie). HONDURAS Atldntida: Tela (quarantine New Orleans, U.S.A.) (T.J.Baker); Colon: Puerto Castilla (J.Bequaert); Comayagua: "Comayaena" (S. Passoa); 1 1.7miS San Antonio, 830m (D.H.Janzen); 1 5.7mi N Siguatepeque, 530m (D.H.Janzen); Minas de Oro (J.B.Edwards); Copdn: 10.4mi S Sta. Rosa de Copan, 980m (D.H.Janzen); 1 1.9mi S Sta. Rosa de Copan, 1130m (D.H.Janzen); 17.3mi N Sta. Rosa de Copan, 780m (D.H.Janzen); Cortes: 24.6mi SW San Pedro Sula, 240m (D.H.Janzen); 6.8mi S San Pedro Sula, 480m [=20.9mi SW Quimistan] (D.H.Janzen); San Pedro Sula (S.C.Bruner; W.M.Mann); Ocotepeque: 4.4mi E [Nueva] Ocotepeque, 13 10m (D.H.Janzen); Santa Barbara: 7.3mi E Quimistan (D.H.Janzen); 13.7mi SW Quimistan, 320m (D.H.Janzen); Yoro: Coyoles, W of Olanchito (Echternacht); dept.unknown: "Hon- duras" (Bates). MEXICO Camp.: 0. Imi S Tenabo (D.H.Janzen); O.Smi E Campeche (D.H.Janzen); 10.6mi E Campeche (D.H.Janzen) ; 20mi E Campeche, Hwy. 1 80 (D.H.Janzen); 29mi E & 12mi S Campeche (Ruinas Edzna)(D.H.Janzen); 48mi NE Puerto Real (Isla Aguada), Hwy. 180 (D.H.Janzen); Ruinas Edzna (U.Kansas Mex.Exped.); Chis.: 10 mi NE [NW?] Tapachula [on Hwy. 200?] (D.H.Janzen); 140 JOURNAL OF HYMENOPTERA RESEARCH 10.8mi S Pichucalco (D.H.Janzen); llkm SE Pichucalco, 400m (P.S.Ward); 11 mi E Arriaga (D.H.Janzen); 1km WSW Palenque, 80m (P.S.Ward); 26km E Cintalpa (W.MacKay); 2mi S Pichucalco (D.H.Janzen); 32mi W [San] Cristobal de las Casas, Hwy.190 (D.H.Janzen); 3km ENE Chiapa de Corzo, 500m (P.S.Ward); 3mi N Soyalo [on Hwy.195] (D.H.Janzen); 4mi NW Ocosingo (R.C.Bechtel & E.I.Schlinger; R.F.Smith); 4mi S Simojovel(R.C.Bechtel & E.I.Schlinger; E.I.Schlinger); 56.9mi NE [NW?] Tapachula [on Hwy.200?] (D.H.Janzen); 5mi SE Tapilula [on Hwy.195] (D.H.Janzen); 6.9mi N Tapilula (D.H.Janzen); 7mi SW Teapa [on Hwy.195] (D.H.Janzen); 8.5mi S La Trinitaria, 1160m (U.Kansas Mex.Exped.); 8.5mi S La Trinitaria, Hwy.190 (D.H.Janzen); 8mi W Las Cruces, Hwy.190, 660m (D.H.Janzen); 96km S Tuxtla Gutierrez, 732m (D.E. & J.A.Breedlove); Acapetahua Las Bugamvillas (F.Diaz); Arriaga (D.H.Janzen); Cd. Cuauhtemoc (D.H.Janzen); Chicoasen (G.N.Collins); El Real (Goodnight & Stannard); Ixtacomitan (R.Andrews); Llano Grande (G.N.Collins); Palenque (c.u.); Pichucalco (G.N.Collins); Rio Huixtla, Huixtla (J.G.Pereira); Ruinas Palenque (E.M.Fisher); San Sebastian [near Tuxtla Gutierrez; see Safford 1922:393] (G.N.Collins); Santo Domingo, 15mi SE [SW?] Simojovel (R.F.Smith); Tapilula (D.H.Janzen); Tonala, 40m (D.H.Janzen); Tonola [prob.=Tonala] (A.Petrunkewitch); Tuxtla Gutierrez (N.L.H.Krauss; W.P.Stoutamize); Yaxoquintela (J.E.Rawlins); Yerba Santa (G.N.Collins); Gro.:10mi NE Acapulco (D.H.Janzen); 15.8mi S Chilpancingo (D.H.Janzen); 18mi S Chilpancingo (F.D.Parker;F.D.Parker & L.A.Stange); 25.4mi S Chilpancingo (D.H.Janzen); 55mi N Acapulco, Hwy.95 (Cornell Univ.Mex.Field Party; c.u.); 57.8mi S Chilpancingo (D.H.Janzen); 59.9mi N Acapulco (D.H.Janzen); 62.4mi N Acapulco (D.H.Janzen); 74km N Acapulco (W.MacKay); Acapulco (L.J.Lipovsky); Revolcadero (N.L.H.Krauss); San Geronimo de Juarez (W.von Hagen); Hgo.: 2km W Orizatlan, 245m (W.MacKay); Mor.:15miSCuernavaca (E.S.Ross; W.S.Ross); Cuernavaca (W.M.Wheeler); Oax.: 1 1.4-17.0mi W Tehuantepec (D.H.Janzen); Imi W Temascal (D.H.Janzen); 22.2mi N Puerto Escondido, 700m (D.H.Janzen); 25mi W Tehuantepec (D.H.Janzen); 3.2miNE Tehuantepec (D.H.Janzen); 42km N San Pedro Pochutla, 850m (W.MacKay); 44mi W Tehuantepec (E.E.Gilbert & C.D.MacNeil); 5mi E Temascal (D.H.Janzen); 9.6km E Santiago Astata, 1 Om (W.MacKay); Bahias de Huatulco (W.MacKay); Pinotepa Nacional (S.W.T.Batra); Salina Cruz (D.H.Janzen); Tehuantepec (F.Knab; W.P.Stoutamize); Temascal (H.V.Daly; D.H.Janzen); Temascal, 25m (D.H.Janzen);Tuxtepec(J.CamelaG.; W.M.Mann); Valle Nacional (G.V.Halffter); Q.Roo: 12.2mi S Peto, Q.Roo- Yucatan border (D.H.Janzen); 16.9mi W Cd. Chetumal, rd. to Peto (D.H.Janzen); 22.5mi S Felipe Carillo Puerto (D.H.Janzen); 6.4mi E Polyuc (D.H.Janzen); 7mi W Felipe Carillo Puerto (D.H.Janzen); 8. Imi S Felipe Carillo Puerto (D.H.Janzen); 8mi S Felipe Carillo Puerto (D.H.Janzen); Sian Ka'an (A.Dejean); Sian Ka'an Reserve, nr. Felipe Carillo Puerto (A.Dejean); Vallarta (A.Dejean); S.L.P. : 27mi N Tamazunchale (D.H.Janzen); 40-50mi NW Cd. del Maiz (W.S.Ross); 4miN Valles, 300ft. (W.S.Creighton); Cd. Valles (D.H.Janzen); El Bonito, 7mi S Cd. Valles, 300ft. (P.H. & M.Arnaud); El Salto (A.Mintzer; c.u.); Huichihuayan (L.J.Lipovsky); Rio Amahac, Tamazunchale, 300ft. (W. S. Creighton); Tamazunchale (D. H. Janzen; W. S. Ross); locality not specified, prob. Tanquian [see Safford 1923:390] (Safford); Tab. : 0.6mi S Paraiso onrd. to Cardenas (D.H.Janzen); 0.9mi S Chontalpa (D.H.Janzen); 12.8mi S Chontalpa (D.H.Janzen); 2. Imi E Frontera (D.H.Janzen); 3 mi W Cardenas (D.H.Janzen); 30.2mi W Cd. El Carmen (D.H.Janzen); 37.8mi E Coatzacoalcos, Hwy.180 (D.H.Janzen); 6.6mi S Chontalpa (D.H.Janzen); Chontalpa, 26mi S Cardenas (D.H.Janzen); Cardenas (D.H.Janzen); Teapa (J.C. & D.Pallister; H.H.Smith; W.P.Stoutamize); Tamps.: 22.7mi S Cd. Victoria (D.H.Janzen); 41mi S Cd. Victoria (C.W.Obrien); 50mi N Valles (G.E.Bohart); 5mi N Cd. Mante (A.Mintzer); 7km WSW El Encino, 140m (P.S.Ward); Antiguo Morelos (c.u.); Cd. Madero (F.Infante M.); Ciudad Mante (N.E. & M.A.Evans; N.L.H.Krauss); El Limon (H.E.Evans); Forlon (L.J.Lipovsky); Gonzales (c.u.); Llera (W.E.LaBerge); Mesa de Llera (A.Mintzer); N of Antiguo Morelos (A.Mintzer); Rio Guayalejo at VOLUME 2, NUMBER 1 , 1993 141 Hwy.85 (A.S.Menke&L.A.Stange); S of Cd. Mante (A.Mintzer); Tampico (Brakhoven; D.L.Crawford; H.Jourdan; N.L.H.Krauss; Locke; E. Palmer; E.A.Schwarz; W.P.Stephen; c.u.); Tampico, dunes at Cd. Madero (D.H.Janzen); Xicotencatl (H.C.Millender); Ver.: "N.M.,Vera Cruz" (Townsend); "Vera Cruz" (G.Seurat; H.H.Smith); lOmi W Veracruz (G.E.Bohart); 14km ENE La Tinaja, 50m (P.S.Ward); 15mi W Veracruz (U.Kansas Mex.Exped.); 16km E Cuilahuac [=Cuitlahuac] (W.MacKay); 24.9miNW Acayucan (D.H.Janzen); 28km N Cardel, Morro de la Mancha (V.Rico-Gray); 30mi S Acayucan (F.D.Parker); 3mi N Sayula (R.C.Bechtel; R.C.Bechtel & E.I.Schlinger); 4mi NE Minatitlan (R.C.Bechtel & E.I.Schlinger);4miNWRinconada Antigua, 1350ft. (U.KansasMex.Exped.); 4mi W Puente Nacional, 900ft. (U.Kansas Mex.Exped.); 6.5km N Tierra Blanca, 50m (W.MacKay); 7mi S Cardel, 600ft. (c.u.); 9km NNW Sontecomapan, 20m (P.S.Ward); Boca del Rio (U.Kansas Mex.Exped.); Buen Pais (R.C.Bechtel & E.I.Schlinger); Camaron (E.Skwarra); Cordoba (F.Knab; R.R.Snelling; c.u.); Cotaxtla Exp. Sta., Cotaxtla (D.H.Janzen); Est. Biol. Los Tuxtlas (H.A.Hespenheide); Est. Biol. "Los Tuxtlas", nr. San Andres Tuxtla (G.Ibarra M.); Fortin (c.u.); Jalapa (Rangel; W.M.Wheeler; c.u.); Jalapilla, mun. Jilotepec (G.Aleman); Los Cocos (A.Petrunkewitch); Los Tuxtlas, 10km NNW Sontecomapan, 200m (P.S.Ward); Mirador (E.Skwarra); Mocambo (D.H.Janzen); Orizaba (c.u.); Palma Sola (Halffter & Reyes); Panuco (F.Parker & D.Miller); Playa Azul, Catemaco (W.P.Stoutamize); Pueblo Nuevo, nr. Tezonapa (Cornell Univ. Mex. Field Party); Remutadero (E.Skwarra); Santa Lucrecia [=Jesus Carranza] (F.Knab; P.Knab); Tamarindo (E.Skwarra); Tamos (F.C.Bishop); Tinajas [presumably La Tinaja, on Hwy.150] (F.D.Parker & L.A.Stange); Tlacocintla (E.Skwarra); Veracruz (G.E.Bohart; N.L.H.Krauss; E.Skwarra; L.A.Stange); Yuc.: 14.8mi S Ticul, "Hwy.180" [prob.Hwy.261] (D.H.Janzen); 8mi E Merida (rd. to Pto. Juarez) (D.H.Janzen); Merida (D.H.Janzen; N.L.H.Krauss); Merida (S margin of town) (D.H.Janzen); Tekax, 33mi W Peto (D.H.Janzen); Temax (Gaumer); state unknown: "Mex"("Norton"). Pseudomyrmex flavicornis (F. Smith 1877) (Figs. 16, 25, 63, 69) Pseudomyrma flavicornis F. Smith 1877:67. Lec- totype worker,Nicaragua (BMNH) [Examined]. Pseudomyrma belli Emery 1890:63. Syntype work- ers, Alajuela, Costa Rica (BMNH, MCSN) [Ex- amined] [Synonymy by Ward 1989:438]. Pseudomyrma belli var. obnubila Menozzi 1927a:273. Syntype worker, San Jose, Costa Rica (H. Schmidt) (NHMB) [Examined] [Syn- onymy by Ward 1989:438]. Pseudomyrma belli subsp. fellosa Wheeler 1942:160. Syntype workers, Nicaragua (W. Fluck); Granada, Nicaragua (C. F. Baker) (AMNH, LACM, MCZC) [Examined] [Syn- onymy by Ward 1989:439]. Pseudomyrmex flavicornis (F. Smith); Kempf 1972:218. Worker measurements (n = 29). HL 1 .06- 1 .42, HW 0.99-1.21, MFC 0.075-0.114, CI 0.83-0.94, REL 0.39-0.45, REL2 0.45-0.51, OOI 1.28-2.71, VI 0.59-0.73, FCI 0.068-0.098, SI 0.40-0.46, SI2 0.82-0.97, NI 0.61-0.68, PLI 0.57-0.67, PWI 0.60- 0.72, PPWI 1.36-1.80. Worker diagnosis. Similar to P. ferrugineus (q.v.) except as follows. Larger, with shorter eyes, on average (Figs. 16,50). Head densely punctulate, opaque; overlying rugulo-punctate sculpture on propodeum tending to be better developed than in P. ferrugineus. Pilosity and pubescence denser on average. Head black, gaster and postpetiole dark brown to black, mesosoma and petiole varying from black to a contrasting lighter brown or red- dish-brown; mandibles, scapes, fronto-clypeal com- plex, and apices of legs brown. Comments. Key traits of this species are the laterally rounded median clypeal lobe, large size (worker HW > 0.98; queen HW 1.12-1.19, n=13), broad opaque head (worker CI > 0.82; queen CI 0.73-0.76) and dark color. P. flavicornis is one of three species in the P. ferrugineus group whose workers and queens have a black or very dark brown body (mesosoma sometimes contrastingly lighter). The other two, P. mixtecusandP. veneficus, are allopatric to P. flavicornis and smaller in size; 142 JOURNAL OF HYMENOPTERA RESEARCH other distinguishing features are mentioned in the key and discussed under those species. A tendency towards lighter coloration of the mesosoma in north- ern populations ofP.flavicornis sometimes makes it difficult to distinguish this species from sympa- tric dark-colored P. ferrugineus. Even the darkest workers and queens of the latter species are, how- ever, smaller (an average difference in workers, almost absolute in P. ferrugineus queens which have HW 0.96- 1 . 1 2 (n = 37)) with longer eyes (Fig. 50) and shorter scapes for a given relative head breadth (Fig. 51); and they show some reflectance of light on the upper third of the head between the ocelli and compound eye in contrast to the more or less opaque-headed P. flavicornis. In addition, P. ferrugineus queens have more elongate heads (CI 0.68-0.73) than those of P. flavicornis. Distribution and biology. This is a monogy- nous species ranging from Guatemala to Costa Rica (Fig. 69), which inhabits Acacia collinsii and, less frequently, A. cornigera and A. hindsii. It was one of the first acacia-ants to be brought to the attention of naturalists, thanks to an early account of its biology by Thomas Belt (1874) (under the name Pseudomyrma bicolor). In the more recent litera- ture P. flavicornis has usually been referred to as "P. belli", but note that there is not a perfect correspondence in name usage (Table 1). Material examined (AMNH, ANSP, BMNH, CASC, CUIC, INBC, LACM, MCSN, MCZC, MZSP, NHBM, NHMV, PSWC, SEMC, UCDC, USNM). COSTA RICA Alajuela: Alajuela (A.Alfaro); Atenas (A.Alfaro); Ojo de Agua (A.Alfaro); Tacares (A.Alfaro); Turrucares (A.Alfaro); Guanacaste: 1.4mi N La Cruz, 200m (D.HJanzen); 10.7mi NW Liberia (D.HJanzen); 1km S Canas (D.HJanzen); 2mi E Playa Coco (D.HJanzen); 2mi SE Canas [=2mi S Canas] (D.HJanzen); 4km S Canas(D.HJanzen); 5km S Liberia (D.HJanzen); 6mi E, 6mi S Canas (D.HJanzen); 6mi W Liberia (D.HJanzen); 7km N Canas (D.HJanzen); Bahia del Coco (A.Alfaro); Ballena, Rio Tempisque (A.Alfaro); El Coco (R J.Hampton); FincaTaboga, 6mi S, 6mi W Canas (D.HJanzen); Hda. LaPacifica, 5km NW Canas (E.R.Heithaus); Hda. La Pacifica, nr. Canas, 50m (P.S.Ward); La Cueva, 12km N Liberia (D.HJanzen); Liberia (A.Alfaro; M.G.Naumann); Palo Verde (D.E.Gill; H.A.Hespenheide; D.HJanzen; D.Whitacre); Palo Verde, 50m (D.M.Olson); Palo Verde, <100m (J.Longino); Rio Corobici, nr.Canas (R.M.Bohart); Santa Cruz (P.P.Calvert); Santa Rosa Natl. Pk. (F Joyce); Santa Rosa Natl. Pk., 300m (J.Longino; P.S.Ward); Santa Rosa Natl. Pk., 5m (P.S.Ward); Santa Rosa Natl. Pk., <5m (P.S.Ward); Tempisque (A.Alfaro); Heredia: Lagunilla (C.H.Ballow); Puntarenas: 1km NE Tarcoles, 20m (P.S.Ward); 4km E Tivives, 5m (L.S.Farley); Barranca,near Puntarenas (A.Alfaro); San Jose: Bebedero (A.Alfaro); Rio Oro (D.HJanzen); San Jose (Nauck;H.Schmidt); Villa Colon (A.Alfaro); Villa Colon, 600-700m (J.Longino); prov. unknown: "Costa Rica"(c.u.); Ciruela(J.F.Tristan). EL SALVADOR Ahuachapan: 7.8mi S Hachadura, 50m (D.HJanzen); Chalatenango: 5 .4mi N La Palma, 850m (D .H Janzen) ; La Libertad: 2.6miS Santa Tecla,1010m[=11.8miNLaLibertad] (D.HJanzen); 2mi E La Libertad (D.HJanzen); La Libertad (E.S.Ross); Quezaltepeque (D.Cavagnaro & M.E.Irwin); La Union: 7. Imi W Amatillo, 190m (D.HJanzen); Lapaz: 11.6mi W Zacatecoluca, Om (D.HJanzen); San Miguel: 0.4mi W San Miguel (D.H Janzen); betw. La Union & San Miguel, 1 10m (D.HJanzen); San Salvador: San Salvador (O.L.Cartwright; N.L.H.Krauss); Sonsonate: 34.4mi W La Libertad (D.HJanzen); 6.6mi S Sonsonate [=43. 6mi W La Libertad] (D.HJanzen); Usulutan: E slope Cerro Verde, 3800ft. (D.Q.Cavagnaro & M.E.Irwin); dept. unknown: Los Chorros (D.Q.Cavagnaro & M.E.Irwin); Los Chorros Natl. Pk. (M.E.Irwin). GUATEMALA Escuintla: 12.6miNEEscuintla, rd. to Cd. Guatemala, 1120m (D.HJanzen); 15km E Escuintla [on CA-9] (D.HJanzen); 43km S Cd. Guatemala [=15km E Escuintla] (D.HJanzen); Guatemala: 19km S Cd. Guatemala [on CA-9] (D.HJanzen); 7.9mi S Cd. Guatemala [on CA-9] (D.HJanzen); Amatitlan (Bates); Escuintla- Cd. Guatemala [=19km S Cd. Guatemala] (D.HJanzen); Lake Amatitlan (c.u.);Jutiapa:47mi S Escuintla, 250m [=47mi SE Escuintla] (D.HJanzen); 7.7mi E Jutiapa, Hwy.l, 900m (D.HJanzen); 9.7mi E Jutiapa, 750m (hwy.to San Cristobal) [=9.3miNE Jutiapa] (D.HJanzen); Santa Rosa: 12.2mi W Taxisco (D.HJanzen); 3.8mi S VOLUME 2, NUMBER 1, 1993 143 Guazacapan (D.H.Janzen); Guazacapan (R.H.Painter); Zacapa: lOmi SW El Lobo, 170m [on CA-9] [=9.2mi NE Piedras de Afilar] (D.H.Janzen); 2.6rai SW Rio Hondo, 200m [on CA-9] (D.H.Janzen); 22.3mi SW Quirigua [on CA- 9] (D.H.Janzen); 22.3mi SW Quirigua [on CA-9] (D.H.Janzen); 8.2mi NE Piedras de Afilar, 160m [on CA-9] [=12.2miNE Rio Hondo] (D.H.Janzen); km 142 on Guatemala-Pto. Barrios Rd. nr. Los Amates (D.H.Janzen). HONDURAS Choluteca: 19mi NE Choluteca (D.H.Janzen); 3.6mi W Choluteca, 200m (D.H.Janzen); 4.5mi W Choluteca (D.H.Janzen); Colon: Puerto Castilla (J.Bequaert); Valle: 4.6mi E Jicaro Galan, 1 90m (D .H. Janzen) ; La Union, 28 .4mi E El Amatillo (frontera) (D.H.Janzen). NICARAGUA Chontales: no specific locality (T.Beit); Esteli: 2mi N Condega, 500m (D.H.Janzen); Granada: 2.2mi W Nandaime (D.H.Janzen); 2mi N Nandaime, 160m (D.H.Janzen); Granada (C.F.Baker); Leon: 28.1mi SE Leon (D.H.Janzen); Managua: S.lmi E San Benito (D.H.Janzen); 8.8mi N Tipitapa (D.H.Janzen); 9.9miNEMasachapa,Hwy.8, 180m (D.H.Janzen); 9mi N Tipitapa, 50m (D.H.Janzen); Matagalpa: 15.8mi NW Sebaco [=15.8mi W Sebaco] (D.H.Janzen); 2.6miNDario (D.H.Janzen); 4.1mi S Matagalpa, 650m (D.H.Janzen); 4.5mi SE Dario (D.H.Janzen); Rivas: Imi N San Juan del Sur (D.H.Janzen); Imi NW Penas Blancas [=lmi N Penas Blancas] (D.H.Janzen); 20.5mi NW Penas Blancas (D.H.Janzen); 4.4miSELa Virgen [=4.4mi S La Virgen] (D.H.Janzen); Isla Ometepe (F.Joyce); La Virgen [on Hwy.l] (D.H.Janzen); San Juan del Sur, 10m (D.H.Janzen); Zelaya: Wounta Hanlover (Fluck); dept.unknown: "Nicaragua" (W.Fluck; c.u.). Pseudomyrmex janzeni Ward, sp. (Figs. 19, 29, 64, 70) nov. Holotype worker. MEXICO, Nayarit: 60 mi. SE Acaponeta, Hwy. 15, 15.ix.1963, D. H. Janzen (LACM). HW 1 .00, HL 1 .08, EL 0.5 1 , PL 0.55, PH 0.36. Paratypes. Same data as holotype: series of 166 workers, 62 queens and 45 males (AMNH, BMNH, CASC, EBCC, GBFM, INBC, LACM, MCZC, MZSP, PSWC, UCDC, USNM). Addi- tional non-type material is listed below. Worker measurements (n = 12). HL 1 .00- 1.18, HW 0.93-1.03, MFC 0.063-0.096, CI 0.88-0.94, REL 0.45-0.47, REL2 0.49-0.52, OOI 1.45-2.29, VI 0.58-0.68, FCI 0.068-0.098, SI 0.42-0.45, SI2 0.84-0.91, NI 0.62-0.69, PLI 0.59-0.71, PWI 0.63- 0.73, PPWI 1.37-1.73. Worker diagnosis. Very similar to P. ferrugineus (q.v.) except as follows. Size smaller, on average. In lateral view mesonotum less steeply inclined; basal and declivitous faces of propodeum forming a less obtuse angle (compare Figs. 27 and 29). Petiole shorter and higher, on average (Fig. 48). Weak rugulo-punctate sculpture on propodeum even less evident than in P. ferrugineus. Pubes- cence denser, becoming decumbent to suberect on parts of body, most notably the gula (Fig. 19). Head and mesosoma rather light orange-brown, gaster the same or a slightly darker brown. Comments. Within the P. ferrugineus group P. janzeni can be characterized by its relatively small size (worker and queen HW < 1.04), broad head (worker CI > 0.86), laterally rounded median clypeal lobe, and uniform orange-brown color. P. janzeni is evidently closely related to P. ferrugineus (as surmised by Janzen 1973); all of the metric measurements and indices of these two species overlap, although there is a tendency for P. janzeni workers to have shorter, higher petioles (Fig. 48). Workers and queens of P. janzeni are perhaps best distinguished from those of P. ferrugineus by the combination of lighter orange-brown color, suberect gular pubescence (best seen in a backlit lateral view of the head), and the flatter profile of the worker mesosoma (see description above and Fig. 29). While some individuals of the highly variable P. ferrugineus approach these conditions there is no indication of a convergence towards this morphol- ogy in western Mexico (Guerrero) where popula- tions of P. ferrugineus come closest to those of P. janzeni. Distribution and biology. First recognized by Janzen (1967a, 1969, 1973) as a distinct but undescribed species, P. janzeni is confined to a limited area in western Mexico (Fig. 70) where it is sympatric with the much darker colored and com- 144 JOURNAL OF HYMENOPTERA RESEARCH moner P. veneficus. Colonies occupy Acacia hindsii and are polygynous; additional details of the life history can be found in Janzen's (1973) paper on polygynous acacia-ants. Material examined. Type material listed above, plus the following (LACM, MCZC, PSWC, UCRC, USNM). MEXICO Jal. : Puerto Vallarta (J. A.Comstock) ; Nay.: 14.5mi E San Bias (D.HJanzen); 2mi E San Bias (R.van den Bosch); 31mi N Tepic (D.HJanzen); 36mi N Tepic (D.HJanzen); 4mi E San Bias (M.Irwin; M.Irwin & E.I.Schlinger; EJ.Schlinger); 5mi E San Bias (F.Parker & D.Miller); Compostela (c.u.); Rio Palillo, 14mi E San Bias (D.HJanzen); Tepic (H.A.Scullen); Sin.: 20mi E Villa Union (E.I.Schlinger). Pseudomyrmex mixtecus Ward, sp. nov. (Figs. 15, 26, 55, 61, 69) Holotype worker. MEXICO, Guerrero: 25.4 mi. S. Chilpancingo, 10.viii.1966, D. H. Janzen #M0088 10966 (LACM). HW 0.97, HL 1.07, EL 0.48, PL 0.55, PH 0.35. Paratypes. Same data as holotype, and three other accession numbers (M0078 10966, M0098 10966, MO 108 10966) with same locality, date, and collector: series of 43 workers, 34 queens and 17 males (AMNH, BMNH, CASC, EBCC, GBFM, INBC, LACM, MCZC, MZSP, PSWC, UCDC, USNM). Additional non-type material is listed below. Worker measurements (n= 13). HLO.94-1.19, HW 0.89-1.03, MFC 0.054-0.073, CI 0.86-0.95, REL 0.42-0.47, REL2 0.46-0.52 OOI 1 .22-2.28, VI 0.61-0.73,FCI0.056-0.073,SI0.43-0.45,SI20.86- 0.97, NI 0.60-0.65, PLI 0.60-0.68, PWI 0.60-0.68, PPWI 1.40-1.73. Worker diagnosis. Similar to P. ferrugineus (q.v.) except as follows. Size smaller (HW < 1.04, LHT < 0.90), head broad (CI > 0.85); frontal carinae separated by about basal scape width or less (FCI2 0.45-0.54). Basal and declivitous faces of propodeum forming a less obtuse angle in profile than typical for P. ferrugineus (compare Figs. 26 and 27). Head densely punctulate, opaque. Stand- ing pilosity rather common, usually some setae exceeding 0.12 mm and 0.20 mm in length on mesosoma dorsum and petiole, respectively. Pu- bescence dense but appressed. Very dark brown to black, appendages lighter. Comments. P. mixtecus is distinguished from all other species, except P. veneficus and P. flavicornis, by its laterally rounded median clypeal lobe, broad head, and black (or very dark brown) body. It differs from P. veneficus by the fully opaque head, absence of conspicuous suberect pu- bescence on the petiole, and larger size. P. mixtecus is evidently closely related to P. flavicornis but averages smaller in size (compare worker HW and LHT values), a difference which is absolute in queens (queen HW 0.96- 1.01 (n=8), whereas queen HW > 1 . 1 1 in P. flavicornis). In addition the petiole is relatively longer and higher, for a given head width, in both workers and queens of P. mixtecus (Figs. 44-47). Distribution and biology. P. mixtecus is known only from the Mexican states of Guerrero and Oaxaca (Fig. 69). Colonies have been collected from Acacia hindsii and A. collinsii, but little more has been recorded about their biology. Janzen's field notes indicate that this species is monogynous. Material examined. Type material listed above, plus the following (CUIC, LACM, MCZC, MZSP, PSWC, SEMC, USNM, WPMC). MEXICO Gro.: lOmi NE Acapulco (D.HJanzen); 29.6mi N Acapulco, 1400ft. (D.HJanzen); 30mi N Acapulco, Hwy.95 (Cornell Univ. Mex. Field Party); 57.8mi S Chilpancingo, Hwy.95 (D.HJanzen); 74km N Acapulco (W.MacKay); Acapulco (Baker; F.Knab; N.L.H.Krauss; LJ.Lipovsky); Puerto Marques (N.L.H.Krauss); San Geronimo de Juarez (W.von Hagen); Oax.:l 1.4-17.0mi W Tehuantepec (D.HJanzen); 13.8mi W Tehuantepec, 1500ft. (D.HJanzen); 19km N San Pedro Pochutla, 200m (W.MacKay); 6.0mi E Niltepec, Hwy.190, 100m (D.HJanzen). Pseudomyrmex nigrocinctus (Emery 1 890) (Figs. 13, 22, 56, 72) Pseudomyrmanigrocincta Emery 1890:64. Syntype workers, queens, males, Alajuela, Costa Rica (A. Alfaro) (BMNH, MCSN, MCZC, MHNG) [Examined]. One syntype worker from MCSN VOLUME 2, NUMBER 1, 1993 145 here designated LECTOTYPE. Pseudomyrma alfariForel 1906:228. Twosyntype workers, Tivives, embouchure de Jesus-Maria, Costa Rica (A. Alfaro) (MHNG) [Examined]. One syntype here designated LECTOTYPE. Syn. nov. Pseudomyrma nigrocinta var. bicincta Santschi 1922:347. Syntype workers, Costa Rica (MHNG, NHMB) [Examined]. One syntype from NHMB here designated LECTOTYPE. Syn. nov. Pseudomyrma peltataMenozzi 1927a:273. Three syntype workers, SanJose, Costa Rica (H. Schmidt) (NHMB) [Examined]. Syn. nov. Pseudomyrmex nigrocincta [sic] (Emery); Janzen 1966:252. Pseudomyrmex nigrocinctus (Emery); Kempf, 1972:221. Worker measurements (n = 21). HL 0.89- 1.08, HW 0.74-0.85, MFC 0.035-0.051, CI 0.75-0.84, REL 0.40-0.45, REL2 0.51-0.56, OOI 1.39-2.76, VI 0.62-0.78, FCI 0.044-0.065, SI 0.44-0.48, SI2 0.81-0.89, NI 0.58-0.64, PLI 0.59-0.68, PWI 0.49- 0.61, PPWI 1.10- 1.30. Worker diagnosis. Small species with elon- gate head and short eyes (REL 0.45, REL2 0.56, EL/LHT 0.61). Palp formula 5,3. Median clypeal lobe rather narrow, its surface and anterior margin convex. Frontal carinae separated by about basal scape width (FCI 0.055). Metanotal groove well marked; basal and declivitous faces of propodeum subequal (Fig. 22). Petiole short (PLI > 0.57), its anterior peduncle broad in dorsal view (PWI3 0.50- 0.61) and not well differentiated from the node (Fig. 22). Petiole lacking expanded posterolateral corners. Postpetiole less broad than in most other species in the P. ferrugineus group (see PPWI values). Head densely punctulate and subopaque, becoming sublucid posteriorly where the punctulae are separated by shiny interspaces. Mesosoma punctulate to (laterally) coriarious-imbricate, sublucid, becoming subopaque on the propodeum. Standing pilosity moderately common (as in Fig. 22); pubescence dense and closely appressed. Or- ange-brown, often with anterolateral fuscous patches on abdominal tergite IV (these form a distinct transverse black band in queens). Comments. Workers and queens of P. nigrocinctus are easily distinguished from all other acacia ants, except P. particeps (see below), by their small size (HW < 0.86 in both castes), elongate head in the worker (worker CI < 0.85), and narrow petiole andpostpetiole (worker PWI3 0.50, worker PPWI 1 .30, queen PWI2 0.57-0.63). The orange color and short eyes are also characteristic. Distribution and biology. P. nigrocinctus is found from Guatemala to Costa Rica, with most records coming from the southern end of its range (Fig. 72). Colonies are monogynous, and have been collected from Acacia collinsii, A. cornigera and A. hindsii. Records from Acacia gentlei and A. globulifera (Beulig & Janzen 1969:59) need to be confirmed because of possible confusion with P. peperi. Janzen' s (1967b) observations on "P. nigrocincta" in Mexico refer to P. peperi. On the other hand descriptions of the biology and behavior of P. nigrocinctus in Costa Rica (Janzen 1973, 1974, 1975, 1983; Beulig & Janzen 1969) are reliably attributed to P. nigrocinctus. Material examined (AMNH, ANSP, INBC, LACM, MCSN, MCZC, MHNG, MZSP, NHMB, PSWC, USNM, WPMC). COSTA RICA Alajuela: Alajuela (A.Alfaro); Atenas (A.Alfaro); Cascajal (A.Alfaro); Escobal (A.Alfaro); Ojo de Agua (A.Alfaro); Turrucares (P.P.Calvert); Guanacaste: 1.4mi N La Cruz (D.HJanzen); 10.7mi NW Liberia (D.HJanzen); lOmi NW Liberia, 70m (D.HJanzen); lOmi NW Liberia, 70m [=10.7mi NW Liberia] (D.HJanzen); 2mi S Canas (D.HJanzen); 4km N Canas (D.HJanzen); 5km S Liberia (D.HJanzen); 7km N Canas (D.HJanzen); El Coco (R.J.Hampton); Finca Taboga, 6mi S, 6mi W Canas (D.HJanzen); Garita (A.Alfaro); Hda. La Pacifica, nr. Canas, 50m (P. S. Ward); La Cueva, 12km N Liberia (D.HJanzen); Palo Verde (D.E.Gill; D.HJanzen); Palo Verde, 50m (D.M.Olson); Santa Cruz (P.P.Calvert); Santa Rosa Natl. Pk., 290m (P.S.Ward);SantaRosaNatl.Pk.,300m(J.Longino; P.S.Ward); Santa Rosa Natl. Pk., 5m (P.S.Ward); Santa Rosa Natl. Pk., <5m (P.S.Ward); Tempisque (A.Alfaro); Puntarenas: 2km E Tivives, <5m (L.S.Farley); Tivives (A.Alfaro); San Jose: 3.5km NE Santiago de Pur (D.HJanzen); San Jose 146 JOURNAL OF HYMENOPTERA RESEARCH (H.Schmidt; c.u.); prov. unknown: "Costa Rica" (c.u.). GUATEMALA Zacapa: 2.0mi NE Rio Hondo, 190m [on CA-9] (D.HJanzen); 22.3mi SW Quirigua [on CA-9] (D.HJanzen). HONDURAS Choluteca: 7.4miNECholuteca, 150m (D.HJanzen). NICARAGUA Boaco: 11.7mi E San Benito (D.HJanzen); Esteli: 13.1mi N San Isidro (D.HJanzen); 2.5mi N Condega, 620m (D.HJanzen); 6.8mi N San Isidro, 780m (D.HJanzen); 7.5mi NW San Isidro, 550m (D.HJanzen); Leon: Izapa (J.M.Maes); Madriz: 3mi W Somoto, 650m (D.HJanzen); Matagalpa: 15.8mi NW Sebaco (D.HJanzen); 2.6mi N Dario (D.HJanzen); 4.5mi SE Dario (D.HJanzen); 4mi S Dario, 350m (D.HJanzen); Rivas: 1km W Penas Blancas (D.HJanzen); C.R. border, Imi N Penas Blancas, <5m [=lmi NW Penas Blancas] (D.HJanzen); Isla Ometepe (F Joyce). Pseudomyrmex particeps Ward, sp. nov. (Figs. 14, 23, 54, 57, 72) Holotype worker. COSTA RICA, Puntarenas: Rincon, Peninsula Osa, 3.iii.l965, D.H. Janzen#III (LACM). HW 0.83, HL 1.10, EL 0.50, PL 0.50, PH 0.31. Paratypes. Same data as holotype: series of 82 workers, 14 males, one queen (AMNH, BMNH, CASC, GBFM, INBC, JTLC, LACM, MCZC, MZSP, PS WC, UCDC, USNM). Additional non- type material listed below. Worker measurements (n = 12). HL 0.93- 1.10, HW 0.77-0.83, MFC 0.037-0.050, CI 0.75-0.84, REL 0.44-0.48, REL2 0.55-0.60, OOI 1.47-1.96, VI 0.65-0.75, FCI 0.048-0.062, SI 0.45-0.49, SI2 0.78-0.83, NI 0.53-0.62, PLI 0.58-0.66, PWI 0.55- 0.60, PPWI 1.03- 1.26. Worker diagnosis. Very similar to P. nigrocinctus (q.v.) except as follows. Eyes longer (REL2 0.55-0.60, EL/LHT 0.59-0.64) (Figs. 14, 42, 43). Front of head more strongly shining. Medium to dark brown; gaster uniformly dark brown or black; mandibles, fronto-clypeal com- plex, and appendages lighter brown. Comments. P. particeps is obviously a very close relative of the allopatric P. nigrocinctus, but there are consistent differences between the two in eye size and color which exceed the limits of variation seen throughout the much wider range of P. nigrocinctus. Workers in the type series of P. particeps also have more elongate heads than those of P. nigrocinctus but this distinction is not seen in other samples. Differences between queens of the two species are more striking with the two known queens of P. particeps having more elongate heads (CI 0.61, compared with 0.67-0.72 in a sample of 1 3 P. nigrocinctus queens) and longer metatibiae relative to head width (LHT/HW 1.12 versus 0.97-1.07 in P. nigrocinctus). Additional alates of P. particeps are needed to confirm these differ- ences and the apparent distinctions in male genita- lia (see male key). Distribution and biology. P. particeps is a rare species known only from the Osa Peninsula and one adjacent locality, in Costa Rica (Fig. 72). It appears to be associated exclusively with Acacia allenii, a forest species (see Janzen, 1974 for more informa- tion aboutthehostplant). In contrast, P. nigrocinctus is found farther north in more open habitats where it typically inhabits Acacia collinsii. The differ- ences in worker morphology between P. particeps and P. nigrocinctus (darker color and more elon- gate head and/or eyes in the former) parallel those observed between populations of P. spinicola from the same areas (see below under P. spinicola), suggesting similar selection pressures associated with more forested habitats and partial (P. spinicola) or exclusive (P. particeps) occupancy of a different Acacia species. Material examined. Type material listed above, plus the following (JTLC, LACM, PSWC). COSTA RICA Puntarenas: 4mi S Rincon (D.HJanzen); Bahia Drake, Osa Penin. (F.Joyce); Corcovado Natl. Pk., Sirena, 50m (J.T.Longino); Rincon (A.R.Moldenke); San Jose: 16.7mi SW San Isidro on Hwy.22, 160m (D.HJanzen). Pseudomyrmex peperi (Forel 1913) (Figs. 12,24,58,71) Pseudomyrma peperi Forel 1913:213. Syntype workers, Patulul, Guatemala (Peper) (MHNG) [Examined]. One syntype here designated LECOTYPE. VOLUME 2, NUMBER 1, 1993 147 Pseudomyrma spinicola race convarians Forel 1913:214. Syntype worker, Patulul, Guatemala (Peper) (MHNG) [Examined] [Synonymy by Ward 1989:452]. Pseudomyrma sabanica [sic] var. saffordiEnzmann 1945:89. Syntype workers, Yerba Santa, Chiapas, Mexico (G. N. Collins) (MCZC) [Ex- amined] One syntype here designated LECTO- TYPE. [Synonymy by Ward 1989:452]. Pseudomyrmex peperi (Forel); Kempf 1972:222. Worker measurements (n = 53). HL 0.86- 1.13, HW 0.76-0.90, MFC 0.034-0.064, CI 0.76-0.89, REL 0.45-0.50, REL2 0.54-0.62, OOI 1.15-2.06, VI 0.59-0.79, FCI 0.042-0.071, SI 0.44-0.49, SI2 0.76-0.88, NI 0.62-0.71, PLI 0.54-0.65, PWI 0.63- 0.75, PPWI 1.41-1.83. Worker diagnosis. Small species (HW < 0.92) with moderately elongate head (Fig. 12); anterior margin of median clypeal lobe straight or slightly produced medially, laterally rounded or subangulate (never sharply angulate as in P. spinicola and P. satanicus). Palp formula 4,3, rarely 5p4,3. Frontal carinae separated by about basal scape width. Mesosomal and petiolar profile typically as in Fig. 24, but in some workers basal and declivitous faces of propodeum less well differentiated and/or anteroventral tooth of petiole more prominent. Petiole and postpetiole broad, the former subtriangular in dorsal view with well developed posterolateral angles (Fig. 24). Dorsum of head obscurely punctulate-coriarious, matte. Remainder of body with finely punctulate to punctulate- coriarious sculpture, opaque to sublucid; propodeum lacking overlying rugulo-punctate sculpture seen in P. ferrugineus. Standing pilosity not especially abundant, sometimes lacking (worn?) on mesonotum. Appressed pubescence abundant but very fine. Light to medium brown, rarely dark brown, the gaster sometimes darker than the rest of body; appendages lighter. Comments. P. peperi is recognized by the fea- tures mentioned above and in the key. The combi- nation of small elongate head, broad posterolaterally angulate petiole, and matte head surface is found in no other acacia ant workers or queens. Distribution and biology. This species has a rather wide distribution, from eastern Mexico to Nicaragua (Fig. 71). It has been collected from Acacia chiapensis, A. collinsii, A. cornigera, A. gentlei, A. globulifera and A. hindsii. P. peperi is apparently polygynous over much of its range, and often occurs sympatrically with the commoner P. ferrugineus. Some aspects of its biology in Mexico are discussed by Janzen ( 1 967b) under the name "P. nigrocincta" . Material examined (AMNH, BMNH, CASC, INHS, LACM, MCZC, MNHG, MZSP, NHMV, PSWC, SEMC, UCDC, USNM). BELIZE Belize: 16mi SW Belize, rd. to Cayo (D.HJanzen); 5.5mi NW Belize, rd. to Chetumal (D.H.Janzen); Cayo: 20km S Augustine, 300m (G.D.Alpert); Sanlgnacio (S.E.Schoenig); Corozal: 15mi S Sta.Elena (Louisville) (D.H.Janzen). EL SALVADOR Ahuachapan: 7.8mi S Hachadura (D.HJanzen); Chalatenango: 2.5mi N Tejutla, rd. to LaPalma, 580m (D.H.Janzen); 4.7mi NW La Palma, 880m (D.H.Janzen); 5.5mi SE La Palma, 1130m (D.H.Janzen); 7.5mi SE Tejutla, 320m (D.H.Janzen); La Libertad: 2-4km S Quezaltepeque (W.L. Brown); 2mi E La Libertad (D.H.Janzen); 5mi N Quezaltepeque (M.E.Irwin); 7.4miNLa Libertad (D.H.Janzen); Hda. Capolinas, 5kmNW Quezaltepeque, 450m (M.E.Irwin); Quezaltepeque (M.E.Irwin); Santa Tecla [=Nueva San Salvador] (P.Berry); La Union: 1 Arm W Amatillo, 190m (D.H.Janzen); between La Union & San Miguel, 100m [=22.3mi S Sirama] (D.H.Janzen); between La Union & Usulatan, 1 50m [=2.6mi S Sirama] (D.H. Janzen); Lapaz: 1 1.6mi W Zacatecoluca, Om (D.H.Janzen); San Miguel: be- tween La Union & San Miguel, 1 10m [=22.3mi E Usulutan] (D.H.Janzen); Santa Ana: 5.3mi NW Santa Ana, 660m (on Hwy.l) (D.H.Janzen); Sonsonate: 24.2mi SE Hachadura (D.H.Janzen); 4.5mi S Sonsonate (D.H.Janzen); 41.4mi NW La Libertad, 10m (D.H.Janzen). GUATEMALA A/to Verapaz: San Joaquin, nr. San Cristobal Verapaz, 1080m (D.H.Janzen); El Progreso: 24.5mi NE Cd. Guatemala [on CA-9] (D.H.Janzen); Escuintla: 1.7mi S Escuintla, 370m [on CA-2] (D.H.Janzen); 43km S Cd. Guatemala [=15km E Escuintla] (D.H.Janzen); Escuintla (W.M.Wheeler); San Jose (E.S.Ross; E.I.Schlinger & E.S.Ross); Guatemala: 19km S Cd. Guatemala 148 JOURNAL OF HYMENOPTERA RESEARCH [on CA-9] (D.HJanzen); 20mi SE Cd. Guatemala, 1060m [on CA-1] (D.HJanzen); 7.9mi S Cd. Gua- temala, 1360m [onCA-9] (D.HJanzen) ;Escuintla- Cd. Guatemala [=19km S Cd. Guatemala] (D.HJanzen); Izabal: 9.9mi SW Quirigua (D.HJanzen); Lago Izabal, 1.5km NE El Estor (D.HJanzen); Quirigua (D.HJanzen; W.M.Wheeler); nr. Mariscos (D.HJanzen); Jutiapa: 11.5ml W Jutiapa, 900m (D.HJanzen); 12.3mi E Guazacapan (D.HJanzen); 2.3mi NW Pijiji [=Pijije] (D.HJanzen); 23mi E Taxisco (G.F. & S.Hevel); 3.4mi N San Cristobal, rd. to Jutiapa, 400m (D.HJanzen); 47mi SE Escuintla, 250m [=47mi S Escuintla] (D.HJanzen); 6.9mi N San Cristobal, 290m (D.HJanzen); 8.4mi N San Cristobal, 280m (D.HJanzen); 9.7mi E Jutiapa, 750m (hwy.to San Cristobal) [=9.3miNE Jutiapa] (D.HJanzen); Peten: 70km NW Tikal (W.R.Tschinkel); Tikal (D.HJanzen; W.R.Tschinkel);fleta//zw/<?:2miNE Champerico (D.HJanzen); 5mi W Retalhuleu (D.HJanzen); 5mi W Retalhuleu, Hwy.CA-2, at Rio Nil (D.HJanzen); Santa Rosa: 6mi S Guazacapan (D.HJanzen); Suchitepequez: Patulul (Peper); Zacapa: lOmi SW El Lobo, 170m [on CA- 9] [=9.2mi NE Piedras de Afilar] (D.HJanzen); 2.0mi NE Rio Hondo, 190m [on CA-9] (D.HJanzen); 2.6mi SW El Lobo, 100m [on CA-9] [= 1 6.6mi NE Piedras de Afilar] (D.HJanzen) ; 5 .6mi NE Rio Hondo, 250m [on CA-9] (D.HJanzen); 8.1ml SW Los Amates, 160m [on CA-9] [=8.0mi NE El Lobo] (D.HJanzen); 9.7mi NE Piedras de Afilar, 150m [on CA-9] [=9.5mi SW El Lobo] (D.HJanzen); Zacapa (W.M.Wheeler); km!42 on Guatemala-Pto. Barrios Rd. nr. Los Amates (D.HJanzen). HONDURAS Choluteca: 19.3mi SW San Marcos de Colon, on Hwy.l (D.HJanzen); 19mi NE Choluteca (D.HJanzen); 20.4mi SW San Marcos de Colon, 490m (D.HJanzen); 3.6mi W Choluteca, 200m (D.HJanzen); 7.4mi NE Choluteca, 150m (D.HJanzen); Colon: Trujillo, 80m (Echternacht); Comayagua: 11.7mi S San Antonio, 830m (D.HJanzen); 4mi N Comayagua, 500m (D.HJanzen); Cortes: 24.6mi SW San Pedro Sula, 240m (D.HJanzen); Francisco Morazdn: 24.3mi S Camayagiiela (Tegucigalpa), 1000m (D.HJanzen); 30.4mi S Camayagiiela (D.HJanzen); 30.5mi S Camayagiiela, 930m (D.HJanzen); Ocotepeque: 2.3mi E [Nueva] Ocotepeque, 1090m (D.HJanzen); Nueva Ocotepeque, 910m (D.HJanzen); Santa Barbara: 13.7mi SW Quimistan, 320m (D.HJanzen); Valle: 18.5mi W Jicaro Galan (D.HJanzen); 4.6mi E Jicaro Galan, 190m (D.HJanzen). MEXICO Camp.: O.lmi S Tenabo, rd. to Becal (D.HJanzen); 0.8mi E Campeche (D.HJanzen); 29mi E & 12mi S Campeche (Ruinas Edzna) (D.HJanzen); 29mi E Campeche (D.HJanzen); 48mi NE Puerto Real (Isla Aguada), Hwy.l 80 (D.HJanzen); 5mi S Tenabo (Campeche-Becal Rd.) (D.HJanzen); Campeche (N.L.H.Krauss); Chis.: 2.4mi E Chiapa de Corzo, Hwy.190, 580m (D.HJanzen); 2kmN Yxhuatan [Ixhuatan], "2miN Tapilula" (D.HJanzen); 32mi W [San] Cristobal de las Casas, Hwy.190 (D.HJanzen); 3km ENE Chiapa de Corzo, 500m (P.S.Ward); 3mi N Soyalo [on Hwy.195] (D.HJanzen); 42.5mi S Comitan, Hwy.190, 680m(D.HJanzen); 5.4mi E Chiapa de Corzo, Hwy.190, 770m (D.HJanzen); 56.9mi NE [NW?] Tapachula [on Hwy.200?] (D.HJanzen); 7.0mi NE [NW?] Tapachula [on Hwy. 200?] (D.HJanzen); 7.5mi NW Cd. Cuauhtemoc, Hwy.190 (D.HJanzen); 8.5mi S La Trinitaria, Hwy. 190 (D.HJanzen); FincaEsmeralda (R.Nettel F.); Puerto de San Benito [=Puerto Madero] (R.Nettel F.); Tonala, 40m (D.HJanzen); Yerba Santa (G.N.Collins); Hgo. : 2km W Orizatlan, 245m (W.MacKay); Oax.: 11.4-17.0mi W Tehuantepec (D.HJanzen); 19km N San Pedro Pochutla, 200m (W.MacKay); 3.9mi E Tehuantepec (D.HJanzen); 5.7mi W "Tapanapec" [=Tapanatepec] (D.HJanzen); 6.0mi E Niltepec ,Hwy.l90, 100m (D.HJanzen); 8.1ml W Niltepec, Hwy.190, 60m (D.HJanzen); Temascal (D.HJanzen); Temascal, 25m (D.HJanzen); Q.Roo: 12.2mi S Peto, Q.Roo- Yucatan border (D.HJanzen); 26.6mi S Felipe Carillo Puerto (D.HJanzen); 5.4mi E Polyuc (D.HJanzen); Cancun (A.Dejean); Cenote de Las Ruinas, 8km NW Polyuc (J.Red et al.); Chetumal (J.C. & D.Pallister); San Miguel, Cozumel I. (N.L.H.Krauss); Sian Ka' an (A.Dejean); Sian Ka' an Reserve, nr. Felipe Carillo Puerto (A.Dejean); S.L.P.: 2mi N Rio Amahac, Tamazunchale, 400ft. (W.S.Creighton); 6mi NW Tamazunchale, 600ft.(Univ.Kansas Mex.Exped.); 8mi W San Joachin (W. J.Gertsch); El Bonito, 7mi S Cd. Valles, VOLUME 2, NUMBER 1, 1993 149 300ft. (P.H. & M. Arnaud); El Salto (W.E.LaBerge); Tamazunchale (D.H.Janzen); Tamazunchale, 600ft. (W.S.Creighton); Ver.: 29.5mi NW Tuxpan, Hwy. 122 [actually Hwy. 127] (D.H.Janzen); Alazan (F.Parker & D.Miller); Cordoba (W.M.Mann); CotaxtlaExp. Sta.,Cotaxtla (D.H.Janzen); Mirador (E.Skwarra); Veracruz (E.Skwarra); Yuc.: 30mi S Merida (P.J.Spangler); 8mi E Merida (rd. to Pto. Juarez) (D.H.Janzen); Itzimna (J.C. & D.Pallister);Merida (D.H.Janzen; N.L.H.Krauss); Oxkutzcab (D.H.Janzen); Sta. Elena, S of Ticul, "Hwy.180" [prob.Hwy.261] (D.H.Janzen); state unknown: "Mex"("Norton"). NICARAGUA Estelt: Imi N Condega, 500m (D.H.Janzen); 2.5mi N Condega, 620m (D.H.Janzen); Leon: San Jacinto (J.M.Maes); Madriz: 3mi W Somoto, 650m [=2.5mi W Somoto] (D.H.Janzen); Nueva Segovia: 7. Imi W Amatillo (D.H.Janzen). Pseudomyrmex satanicus (Wheeler 1942) (Figs. 10, 20, 59, 68) Pseudomyrma satanica Wheeler 1 942: 1 74. Syntype workers, queen, male, Rio Agua Salud, Canal Zone, Panama (W. M. Wheeler) (AMNH, LACM, MCZC) [Examined]. One MCZC syntype worker here designated LECTOTYPE. Pseudomyrmex satanica [sic] (Wheeler); Janzen 1966:252. Pseudomyrmex satanicus (Wheeler); Kempf 1972:223. Worker measurements (n= 15). HL 1.16-1.36, HW 1.10-1.26, MFC 0.035-0.057, CI 0.90-0.97, REL 0.45-0.50, REL2 0.48-0.52, OOI 0.92-1.67, VI 0.69-0.78, FCI 0.030-0.049, SI 0.45-0.49, SI2 0.88-1 .00, NI 0.63-0.68, PLI 0.47-0.54, PWI 0.46- 0.63, PPWI 1.35-1.54. Worker diagnosis. Similar to P. spinicola (q.v.) except as follows. Larger (HW > 1 .09), head broader (CI > 0.88) (Fig. 34) with straight or slightly con- cave posterior margin and subangulate posterolat- eral corners (Fig. 10). (The posterior margin of the head approaches this condition in some P. spinicola workers but these have much smaller, more elon- gate heads, HW < 1 . 10, CI < 0.90.) Median clypeal lobe narrower (CLW/HW 0.20-0.22; see Fig. 33). Palp formula 4,3. Head with pronounced pit-like impression below the median ocellus (absent or poorly developed in P. spinicola). Metanotal groove better developed, longer. Petiole tending to be more slender, with less distinct posterolateral cor- ners (this characteristic seen in some workers of P. spinicola, especially individuals from Panama). Body pubescence averaging thicker than in P. spinicola. Dark brown in color, mandibles and appendages lighter. Comments. The foregoing diagnosis will al- low discrimination of P. satanicus workers from those of the closely related P. spinicola; queens can be recognized by size alone (HL > 1.65, HW > 1.20). P. satanicus can be distinguished from the remaining members of the P.ferrugineus group by the emarginate, laterally angulate median clypeal lobe of the worker and the large size of the queen. Distribution and biology. P. satanicus is a forest species restricted to a few localities in central Panama where its host plant, Acacia melanoceras, grows (Fig. 68). Both the ant and plant are intoler- ant of forest clearance and are considered vulner- able to extinction (Janzen 1974). The ant is polygy- nous, with 5-20 or more queens per colony, and the workers are particularly aggressive, even for aca- cia-ants (Wheeler 1942; Janzen 1974). See Janzen (1974:43-53) for additional details on P. satanicus and its host plant. Material examined (AMNH, LACM, MCZC, PSWC, USNM). PANAMA Canal Zone: "Canal Zone" (A.H.Jennings); 3miSWGatun Dam (D.H.Janzen); Barro Colorado Island (D.H.Janzen); France Field (G.C. Wheeler); Marajal [Majagual] nr. Colon (W.M. Wheeler); Red Tank (W.M.Wheeler); Rio Agua Salud (W.M.Wheeler); Zorra Island (D.H.Janzen); Panama: Rio Piedras (D.H.Janzen); prov. unknown: "Panama"(c.u.). Pseudomyrmex spinicola (Emery 1 890) (Figs. 11,21,60,68) Pseudomyrma spinicola Emery 1890:64. Lecto- type worker, Alajuela, Costa Rica (Alfaro) (MCSN) [Examined]. Pseudomyrma spinicola race atrox Forel 1912:24. 150 JOURNAL OF HYMENOPTERA RESEARCH Syntype workers, Panama (Christophersen) (MHNG, NHMB) [Examined]. Syn. nov. One syntype from MHNG here designated LECTO- TYPE. Pseudomyrma spinicola race Gaigei Forel 1914:615. Syntype workers, Columbien (Gaige) (MHNG), Fundacion, Colombia (F. M. Gaige) (LACM, MCZC) [Examined]. Syn. nov. Pseudomyrma spinicola subsp. infernalis Wheeler 1942:180. Syntype workers, queens, males, Venado, Canal Zone, Panama (W. M. Wheeler), Red Tank, Canal Zone, Panama (W. M. Wheeler), and Las Sabanas, Panama (W. M. Wheeler) (AMNH, MCZC) [Examined]. One MCZC worker, from Red Tank, here designed LECTO- TYPE. Syn. nov. Pseudomyrma spinicola subsp. scelerosa Wheeler 1942:181. Syntype workers, Granada, Nicara- gua (C. F. Baker) (AMNH, MCZC) [Exam- ined] . One MCZC worker here designated LEC- TOTYPE. Syn. nov. Pseudomyrma spinolae [sic] var. infernalis Enzmann 1945:91. Syntype workers, queens, Red Tank, Canal Zone, Panama (W. M. Wheeler) (MCZC) [Examined] [Objective synonym of P. spinicola subsp. infernalis Wheeler; Brown 1949:43]. Pseudomyrma spinolae [sic] var. scelerosa Enzmann 1945:91. Syntype workers, Granada, Nicaragua (C. F. Baker) (MCZC) [Examined] [Objective synonym of P. spinicola subsp. scelerosa, Wheeler; Brown 1949:43]. Pseudomyrmex spinicola (Emery); Wheeler and Wheeler 1956:386. Worker measurements (n = 41). HLO.99-1.28, HW 0.94-1.15, MFC 0.032-0.067, CI 0.84-0.97, REL 0.42-0.47, REL2 0.45-0.54, OOI 1.22-2.77, VI 0.64-0.83, FCI 0.032-0.061, SI 0.45-0.50, SI2 0.88-1.05, NI 0.61-0.69, PLI 0.47-0.64, PWI 0.49- 0.71, PPWI 1.32-1.85. Worker diagnosis. Median clypeal lobe emar- ginate, laterally angulate (Fig. 11), relatively broad (CLW/HW 0.21-0.25). Palp formula 5,3 (rarely 5p4,3). Frontal carinae relatively close, and me- dian lobes of antennal sclerites rather exposed (FCI2 0.24-0.42). Head longer than broad but variably so (see range of CI values). Posterior margin of head ranging from broadly convex (Fig. 11) to straight or even weakly concave, usually rounding gently into the sides of head. Basal face of propodeum subequal to declivitous face, round- ing into latter; in dorsal view propodeal spiracles salient,protruding laterally. Petiole generally slen- der (PLI <0.65) with a well developed anterior peduncle; in dorsal view posterolateral angles typi- cally prominent. Head densely punctulate, sublucid, interspaces small (punctulae essentially contigu- ous on most of head) but shiny. Mesosoma finely punctulate dorsally becoming punctulate-coriarious laterally, sublucid; propodeum lacking overlying, coarser rugulo-punctate sculpture. Standing pilos- ity usually moderately common on body dorsum and including some hairs > 0.20 mm. Appressed pubescence common on most surfaces. Varying from light orange-brown to dark brown in color. Comments. The short, broad, emarginate and laterally angulate median clypeal lobe (Fig. 11) distinguishes the worker of this species. The sublucid integument, elongate petiole, prominent propodeal spiracles, and somewhat angulate poste- rolateral corners of the petiole are also characteris- tic. In addition, queens and workers of P. spinicola have more elongate scapes and legs than those of all other species except P. satanicus(Figs. 30,31). For differences between P. spinicola and the closely related P. satanicus see under the latter species. P. spinicola is a variable taxon and has received several infraspecific names, here considered junior synonyms. Southeastern populations (from the Rio Grande de Tarcoles in Costa Rica east through Panama to northern Colombia) are somewhat dif- ferentiated from the others, with the workers and queens tending to have more elongate heads, darker color, and more slender petioles with less pro- nounced posterolateral angles (see Figs. 34, 35). In Costa Rica the contrasts between the two sets of populations are rather striking, and are perhaps accentuated by habitat differences since some (but not all) the southeastern populations are associated with Acacia allenii growing in forested situations, while the northern populations are primarily from Acacia collinsii in open habitats. Samples from Panama (all associated with A. collinsii) are more variable and partly bridge the phenotypic gap. It is possible that more than one species is masquerad- VOLUME 2, NUMBER 1, 1993 151 ing in this variation but the evidence remains am- biguous. Distribution and biology. P. spinicola is a monogynous species, distributed from Honduras to northern Colombia (Fig. 68), which is associated with Acacia collinsii and, less frequently, Acacia allenii and A. cornigera. Janzen (1983) provides a good summary of its biology in Costa Rica, under the name "P. ferruginea". Observations on "P. ferruginea" in Costa Rica, Nicaragua, Panama and Isla Providencia (Janzen 1969, 1974, 1975, 1983) refer to P. spinicola', true P. ferrugineus does not occur south of Honduras and El Salvador. Material examined (AMNH, ANSP, BMNH, CUIC, FFIC, GBFM, GCWC, INBC, JTLC, KSUC, LACM, MCSN, MCZC, MHNG, MZSP, NHMB, PSWC, UCDC, USNM). COLOMBIA Atlantico: Cuatro Bocas, 200m (J. F.G.Clarke); Bolivar. Hda. Monterey, 50m (G.Fagua; F.Fernandez); Magdalena: Aracataca (P.J.Darlington); Fundacion (F.M.Gaige); Fundacion, Santa Marta Mts.,300ft. (F.M.Gaige); San Andres y Providencia: "Old Providence Isl." (D.Fairchild); Isla Providencia, 300ft.(D.H.Janzen); dept. unknown: "Columbien" (Gaige). COSTA RICA Alajuela: Alajuela (A.Alfaro); San Mateo (P.Biolley); Surubres, nr. San Mateo (P.Biolley); Turriicares (A.Alfaro); Cartago: Turrialba (c.u.); Guanacaste: 10.7mi NW Liberia (D.H. Janzen); 2mi S Canas (D.H. Janzen); 5km S Liberia (D.H.Janzen); 6mi W Liberia (D.H.Janzen); 7km N Canas (D.H.Janzen); Canas, "La Pacifica" (R.L.Jeanne); Finca La Pacifica (D.W.Davidson); Garita (A.Alfaro) ; Hda. Comelco, 24km NW Canas (InterAm Hwy) (E.R.Heithaus); Hda. La Pacifica, nr. Canas, 50m (P.S.Ward); Palo Verde (D.E.Gill; E.Guerrant & P.Fiedler; H.A.Hespenheide; D.H. Janzen) ;Palo Verde, 50m (D.M.Olson); Palo Verde, < 1 00m (J.Longino) ; Rio Corobici, nr. Canas (R.M.Bohart); Santa Rosa Natl. Pk.(E.M.Barrows); SantaRosaNatl.Pk.,300m(J.Longino;P.S.Ward); Santa Rosa Natl. Pk., 5m (P.S.Ward); Santa Rosa Natl. Pk., <5m (P.S.Ward); Heredia: "15mi SE Pto.Viejo" [15km SW Pto.Viejo] (D.H.Janzen); Puntarenas: l-5mi NW Rincon (D.H.Janzen); 14.1mi N Golfito (D.H.Janzen); 14km E Palmar Norte, 70m (P.S.Ward); 1km NE Tarcoles, 20m (P.S.Ward); 21.6 rd.mi NE Palmar Norte, 90m (D.H.Janzen); 3.4miSEGolfito, 30m (D.H.Janzen); 4mi SW Rincon (D.H.Janzen); Corcovado Natl. Pk. (D.W.Davidson; J.T.Longino); Corcovado Natl. Pk., Llorona (J.T.Longino); Corcovado Natl. Pk., Sirena, 100m (P.S.Ward); Corcovado Natl. Pk., Sirena, 10m (P.S.Ward); Entrada Boruca, 20km NE Palmar Sur (D.H.Janzen) ; Osa Penin., nr. Rincon (D.H.Janzen); Reserva Biol. Carara, 30m (P.S.Ward);Rincon (D.H.Janzen); Rio Terraba, nr. Palmar Sur (D.H.Janzen); San Jose: 16.4mi SW Sanlsidro, 160m (D.H. Janzen); 3. 5km NE Santiago de Pur (D.H.Janzen); Santa Ana (D.H.Janzen); Tarrazu [Rio?] (A.Alfaro); Villa Colon (A.Alfaro; D.H.Janzen); Villa Colon, 880m (A.Alfaro). HONDURAS Choluteca: 1 1 . 1 mi NE Choluteca, 450m (D.H.Janzen); 3.6mi W Choluteca, 200m (D.H.Janzen); Colon: El Canal, Puerto Castilla (W.M.Mann); Roetan Isl. [Isla de Roatan] (M.Bates); Trujillo, 80m (Echternacht). NICARAGUA Boaco: Empalme do Boaco [=ElEmpalme?] (Echternacht); Chontales: no spe- cific locality (Janson); Esteli: 7.5mi NW San Isidro, 550m (D.H.Janzen); Granada: Granada (C.F.Baker); Leon: 19mi SE Leon [=3.5mi N Pto.Somoza (Sandino)] (D.H.Janzen); 28.1mi SE Leon (D.H.Janzen); Madriz: 13.9mi from Hondu- ras, on Nic.border, Hwy.l (D.H.Janzen); 2.5mi W Somoto (D.H.Janzen); Managua: 20mi N Tipitapa, 90m [=19.4mi N Tipitapa] (D.H.Janzen); 8.1mi E San Benito (D.H.Janzen); 9mi N Tipitapa, 50m [=8.8mi N Tipitapa] (D.H.Janzen); Matagalpa: 15.8mi NW Sebaco (D.H.Janzen); 2.6mi N Dario (D.H.Janzen); 4.1mi S Matagalpa, 650m (D.H.Janzen); 4mi S Dario, 350m [=4.5mi SE Dario] (D.H.Janzen); 4mi S Dario, 350m (D.H.Janzen); Rivas: C.R. border, Imi N Penas Blancas, <5m [=lmi NW Penas Blancas] (D.H.Janzen); Isla Ometepe (F.Joyce); San Juan del Sur, 10m [=lmi N San Juan del Sur] (D.H.Janzen). PANAMA Canal Zone: 7.5mi NW Balboa (between Summit Gdn. &Paraiso) (D.H.Janzen); Ancon (S.F.Blake); Barro Colorado Island (We- ber); Cerro Galera (P.S.Ward); Chivachiva trail (W.M.Wheeler); Chivachiva trail, nr. Red Tank (W.M.Wheeler); Culebra [presumably CulebraCut] (D.D.Gaillard); E end of Madden Dam (D.H.Janzen); Gamboa (N.Banks); Howard AFB, 152 JOURNAL OF HYMENOPTERA RESEARCH W of Panama City, 50m (W.L.Brown et al.); Mad- den Dam (D.Quintero et al.); Paraiso (A.Busck); Red Tank (W.M. Wheeler); Ruta 1, 14kmWPanama City, 100m (W.L.Brown et al.); Venado (W.M. Wheeler); W end Madden Dam (D.HJanzen); Chiriqui: 10.7mi ESE Concepcion (D.H.Janzen); 12.9mi E Remedies (D.HJanzen); 19.6mi E Sapotilla, 50m (D.HJanzen); 7.2mi W Remedies (D.HJanzen); 9.5mi S Boquete, 620m (D.HJanzen); Code: 0.3mi W Agua Dulce, 50m (D.H.Janzen); 10.4miNE SantaMaria, 60m [=1 .9mi W Agua Dulce, Hwy. 1] (D.HJanzen); 2.7mi SW Penonome (D.H.Janzen); Herrera: Cerro Guacamaya, Albina al N. de Monagrillo (D.Quintero et al.); Los Santos: 3.1mi N Pedasi (D.HJanzen); Azuero Penin., 5.4mi SE Los Santos, <5m (D.H.Janzen); Panama: 18.6mi SW Chepo (D.HJanzen); Bella Vista (N.Banks); Las Sabanas (G.C.Wheeler; W.M.Wheeler); Las Sabanas, Panama City (H.F.Dietz); Rio Corona, S of El Valle, 2000ft. (C.W.Rettenmeyer); Rio Tetita, San Carlos (F.D.Rattinibane); savannah nr. Juan Diaz (Weber); Veraguas(l): LasPalmas (c.u.); Veraguas: 4km NW Santiago (D.Quintero); prov. unknown: "Panama" (Christophersen). Pseudomyrmex veneficus (Wheeler 1942) (Figs. 17, 28, 62, 69) Pseudomyrma belli subsp. venefica Wheeler 1942:162. Syntype workers, males, queens, Escuinapa, Sinaloa, Mexico (J. H. Batty) (AMNH, MCZC) [Examined]. One MCZC syntype worker here designed LECTOTYPE. Pseudomyrma belli subsp. venifica Enzmann 1945:81. Syntype workers, queens, Manzanillo, Colima, Mexico (C. H. T. Townsend) (MCZC) [Examined] [Synonymy by Brown 1949:42]. Pseudomyrmex venefica [sic] (Wheeler); Janzen 1969:241. Pseudomyrmex belli veneficus (Wheeler); Kempf 1972:216. Pseudomyrmex veneficus (Wheeler); Ward 1989:439. Worker measurements (n= 12). HLO.95-1.04, HW 0.85-0.95, MFC 0.045-0.073, CI 0.88-0.95, REL 0.44-0.47, REL2 0.47-0.52, OOI 1.26-2.30, VI 0.66-0.75, FCI 0.051-0.081, SI 0.43-0.46, SI2 0.85-0.94, NI 0.58-0.65, PLI 0.60-0.67, PWI 0.58- 0.67, PPWI 1.35-1.73. Worker diagnosis. Similar to P. ferrugineus (q.v.) except as follows. Smaller (LHT 0.69-0.80), with broad head (CI > 0.87); frontal carinae sepa- rated by basal scape width or less (FCI2 0.40-0.60); petiole short (PL 0.43-0.54) and relatively narrow (see PWI values) with somewhat rounded postero- lateral angles (Fig. 28). Head densely punctulate, subopaque to sublucid, with weak silvery reflec- tance. Overlying rugulo-punctate sculpture on propodeum weak and ill-defined. Standing pilosity variable in abundance, becoming rather short ( 0.10 mm) and sparse in southern populations. Pu- bescence thick and conspicuous, suberect on some surfaces especially the propodeum and petiole; suberect pubescence on petiolar dorsum contrast- ing with the appressed pubescence on the postpetiole (Fig. 28). Very dark greyish-brown to black, parts of the mesosoma and petiole sometimes with lighter yellowish brown (more consistently so in the queen). Comments. The small size (worker HW < 0.96; queen HW 0.84-0.96, n=12), conspicuous suberect pubescence on the propodeum and petiole, and black coloration of the head and gaster distinguish workers and queens of P. veneficus. The related species, P. flavicornis, is larger (worker HW > 0.98, queen HW 1.12-1.19) with a broader and more robust petiole (Figs. 25, 28). Workers and queens of P. flavicornis also lack the sublucid head and conspicuous suberect pubescence characteris- tic of P. veneficus. P. mixtecus is somewhat inter- mediate between these two - it has the head sculp- ture and pubescence typical of P. flavicornis but approaches P. veneficus in size (worker and queen head widths overlapping, although only slighter in the queens where HW 0.96-1.01 (n=8) in P. mixtecus) and petiolar dimensions (Figs. 44-47). Distribution and biology. P. veneficus has a limited distribution in western Mexico (Sinaloa to Michoacan) (Fig. 69) where colonies occupy Aca- cia hindsii and, at one locality, A. collinsii. Janzen (1973) gives a detailed description of the ecology and behavior of this highly polygynous, effectively unicolonial, species whose colonies are among the largest of all social insects (containing millions of workers and several hundred thousand queens). VOLUME 2, NUMBER 1, 1993 153 Material examined (AMNH, CASC, EBCC, INKS, LACM, MCSN, MCZC, MZSP, PSWC, UCDC, UCRC, USNM). MEXICO Col: 9 Ami NW Manzanillo (D.H.Janzen); Manzanillo (C.H.T.Townsend; W.M.Wheeler); Paso del Rio, 200ft. (IJ.Cantrall); JaL: 2km E Chamela, 20m (P.S.Ward); 5km E Chamela, 50m (P.S.Ward); 6mi NE El Rincon, 1600ft. (R.J.Hamton); Barra de Navidad (N.L.H.Krauss); Chamela (RJ.McGinley; J.F.Watkins);M/c/z.: 1.1 mi N Gabriel Zamora, 820m (D.H.Janzen); 1.5miNLaMira (D.H.Janzen); 15km WNW Playa Azul, 50m (P.S.Ward); Nay.: 12mi NE San Bias (W.J.Gertsch & W.Ivie); 16mi NW Tepic (W.E.LaBerge); 3 Imi N Tepic (D.H.Janzen); 37mi N Tepic (D.H.Janzen); 4mi E San Bias (M.E.Irwin); Rio Palillo, 14mi E San Bias (D.H.Janzen); Sin.: 14.6mi S Mazatlan (D.H.Janzen); 20mi E Villa Union (E.I.Schlinger); 20mi E Villa Union, 235m (M.E.Irwin; E.Schlinger et al.); 20mi S Villa Union (E.I.Schlinger); 5mi E Concordia (W.J.Gertsch & J.A.Woods); Escuinapa (J.H.Batty); Palmito (L.de Mauzo); Piedra Blanca (R.M.Bohart); state unknown: "Mexico"(c.u.). OTHER ACACIA-ASSOCIATED ferrugineus group spimcola V spinicola + satanicus satanicus Figs. 67- 72. Distributions of species in the Pseudomyrmex ferrugineus group. 154 JOURNAL OF HYMENOPTERA RESEARCH PSEUDOMYRMEX FROM CENTRAL AMERICA Introduction Three of the species discussed below (Pseudomyrmex nigropilosus, P. simulans and P. subtilissimus) are obligate inhabitants of Central American swollen-thorn acacias, although they are not closely related to the P. ferrugineus group (Ward 1991). A fourth species, P. reconditus, is known only from a single collection, made in association with Acacia collinsii. The remaining six species (P. boopis, P. gracilis, P. hesperius, P. ita, P. kuenckeli and P. opaciceps) are non-special- ist Pseudomyrmex which have been collected only occasionally from acacias. These taxa are included for completeness, and their presentation here ne- cessitates a certain amount of taxonomic house- cleaning. One could expect additional generalist Pseudomyrmex to be found in living or dead acacia thorns. Menozzi (1927b) mentions collections by H. Schmidt of "Pseudomyrma flavidula" and "P. brunnea" from Acacia "spadicigera" (probably A. collinsii) near San Jose, Costa Rica. I have not examined the ant specimens in question but they probably belong to P. pallidus (F. Smith) and P. ejectus (F. Smith), respectively. Diagnoses of these species appear in Ward (1985). Finally, mention should be made of other Neotropical acacias which are apparently not myrmecophytes, but which may harbor opportunistic Pseudomyrmex species in their spines: Acacia daemon in Cuba with P. pazosi, P. simplex and P. cubaensis (Berazain & Rodriguez 1983; Pseudomyrmex nomenclature follows Ward 1989), and A. coven in Paraguay with P. gracilis (s.l.) and one or more species in the P. pallidus group (Wheeler 1942; Ward 1991). Synonymic list of species P. boopis (Roger 1863b) = P. modestus (F. Smith 1862) (preoccupied) = P. thoracicus (Norton 1868b) syn. nov. = P. excavatus (Mayr 1870) (Kempf 1967) = P.flaviventris (Emery 1896) (Kempf 1960) = P.fusciceps (Santschi 1931) (Kempf 1960) = P. guatemalensis (Enzmann 1945) (Kempf 1960) P. gracilis (Fabricius 1804) = P. bicolor (Guerin 1844) syn. nov. = P. sericatus (F. Smith 1855) syn. nov. = P. dimidiatus (Roger 1863a) syn. nov. = P. mexicanus (Roger 1863a) syn. nov. = P. variabilis (F. Smith 1877) (Ward 1989) = P. pilosulus (F. Smith 1877) syn. nov. = P. volatilis (F. Smith 1877) syn. nov. = P. canescens (F. Smith 1877) syn. nov. = P. guayaquilensis (Forel 1907) (unavailable name) = P. glabriventris (Santschi 1922) syn. nov. = P. veliferus (Stitz 1933) syn. nov. = P. longinodus (Enzmann 1945) (Brown 1949) P. hesperius, sp. nov. P. ita (Forel 1906) stat. nov. = P. acaciarum (Wheeler 1942) syn. nov. = P. acaciorum (Enzmann 1945) (Brown 1949) P. kuenckeli (Emery 1890) = P. dichrous (Forel 1904) (Kempf 1961) = P. bierigi (Santschi 1932) (Kempf 1961) = P. crenulatus (Enzmann 1945) (Kempf 1961) P. nigropilosus (Emery 1890) P. opaciceps, sp. nov. P. reconditus, sp. nov. P. simulans Kempf 1958 P. subtilissimus (Emery 1890) SPECIES ACCOUNTS Pseudomyrmex boopis (Roger 1863b) (Fig. 1) Pseudomyrma modesta F. Smith 1862:32. Holo- type (unique syntype) worker, Panama (Stretch) (BMNH) [Examined]. [Preoccupied by P. modesta F. Smith 1 860 = Tetraponera modesta (F. Smith).] Pseudomyrma boopis Roger 1863b:25. Replace- ment name for Pseudomyrma modesta. Pseudomyrma thoracica Norton 1868b:8. Syntype workers, Cordova, Mexico (Sumichrast) [Not examined; see comments below]. Syn. nov. Pseudomyrma excavata Mayr 1870:410. Syntype workers, "N. Granada" (BMNH, MHNG, NHMV) [Examined] [Synonymy by Kempf VOLUME 2, NUMBER 1, 1993 155 1967:2]. Pseudomyrma excavata var. flaviventris Emery 1896:2. Syntype workers, Darien, Panama (Festa) (MCSN, MHNG) [Examined] [Syn- onymy by Kempf 1960:22]. Pseudomyrma excavata var. fusciceps Santschi 1931:271. Two syntype workers, France Field, Panama (A. Bierig) (NHMB) [Examined] [Syn- onymy by Kempf 1960:22]. Pseudomyrma spinicola subsp. modesta F. Smith; Wheeler 1942: 105. Pseudomyrma tenuis var. guatemalensis Enzmann 1945:92. Holotype worker, Escuintla, Guate- mala [Not examined] [Synonymy by Kempf 1960:22]. Pseudomyrmex boopis (Roger); Kempf 1967:2. Worker diagnosis. Medium-sized species (HW 1 . 1 6- 1 .29) in the P. tenuis group, with a broad head (CI 0.92-1.02), tectiform and laterally rounded median clypeal lobe, large eyes (REL 0.66), and laterally marginate pronotum. Mesosoma arched and angular in profile; petiole short, high and thin, laterally marginate, with a gently ascending anterodorsal face which rounds into a much steeper (almost vertical) posterior face (Fig. 1). Standing pilosity sparse, lacking on the mesonotum, propodeum, and petiole. Color highly variable, ranging from light testaceous brown to bicolored orange and black (usually with the gaster and pronotum lightest in color) to dark brown. Taxonomic comments. For a more detailed description of this species see Kempf (1960:23). I have synonymized P. thoracicus (Norton) under P. boopis on the basis of Norton's (1868b) original description and the biological notes of Sumichrast in Norton (1868a). In combination these clearly suggest P. boopis rather than any other Pseudomyrmex known to occur in southern Mexico. Although the type material of P. thoracicus is presumably lost, additional indirect evidence of its identity can be found in Gustav Mayr's collection in Vienna (NHMV) where there is a P. boopis worker from Colombia ("Neugranada") identified by Mayr as "P. thoracica Norton". This take son added significance when it is realized that Mayr was apparently the recipient of some of Norton's material. During a brief visit to NHMV I noted specimens of several species, including P. ferrugineus, P. peperi, P. elongatulus (Dalla Torre) and P. brunneus (F. Smith) (although unfortunately not P. boopis), labelled "Mex. Norton" or "N. Am./ Norton". Distribution and biology. P. boopis occurs in rainforest and tropical moist forest from southern Mexico to Ecuador, Venezuela and northern Brazil. This species is less arboreal than most Pseudomyrmex, and nests typically in rotten wood on or near the ground. The type specimen of P. boopis came from a nest in a swollen-thorn acacia (Smith 1862:33), however, and Janzen found colo- nies in thorns of Acacia melanoceras seedlings in Panama. Pseudomyrmex gracilis (Fabricius 1 804) (Fig. 6) Formica gracilis Fabricius 1804:405. Lectotype worker, Essequibo, Guyana (ZMUC) [Exam- ined]. Pseudomyrma bicolor Guerin 1844:427. Syntype queen (unique?), Colombia (ZSMC) [Exam- ined] Syn. nov. Pseudomyrma sericata F. Smith 1855:159. Holo- type (unique syntype) worker, Brazil (BMNH) [Examined] Syn. nov. Pseudomyrma dimidiataRoger 1863a:177. Syntype workers, Colombia (not in MNHN or ZMHB) [Not examined] Syn. nov. Pseudomyrma mexicana Roger 1863a: 178. Syntype workers, Mexico (not in MNHN or ZMHB) [Not examined] Syn. nov. Pseudomyrma variabilis F. Smith 1877:62. Lecto- type worker, Barbadoes (BMNH) [Examined] [Synonymy by Ward 1989:439]. Pseudomyrma pilosula F. Smith 1877:62. Two syntype workers, Barbadoes (BMNH) [Exam- ined]. One syntype here designated LECTO- TYPE. Syn. nov. Pseudomyrma volatilis F. Smith 1877:65. Holo- type (unique syntype) male, Mexico (BMNH) [Examined] Syn. nov. Pseudomyrma canescens F. Smith 1877:66. Holo- type (unique syntype) queen, Abydos, Brazil (BMNH) [Examined] Syn. nov. 156 JOURNAL OF HYMENOPTERA RESEARCH Pseudomyrma gracilis var. glabriventris Santschi 1922:345. Syntype workers, Izozo, Bolivia (Lizer & Deletang) (NHMB) [Examined] Syn. nov. Pseudomyrma gracilis mexicana var. guayaquilensis Forel 1907:7. Worker, Guayaquil, Ecuador (Buchwald) (MHNG) [Ex- amined] Unavailable infrasubspecific name. Pseudomyrma gracilis var. velifera Stitz 1933:68. Holotype queen, Champerico, Guatemala (Paessler) (not in ZMUH; Weidner 1972) [Not examined] Syn. nov. Pseudomyrma gracilis var. longinoda Enzmann 1945:87. Syntype worker, Peru (MCZC) [Ex- amined] [Synonymy by Brown 1949:43]. Pseudomyrmex gracilis (Fabricius); Kusnezov 1953:214. Worker diagnosis. With the traits of the gracilis group (see couplet 6 of the key; p. 130) and the following more specific features. Head broad, about as wide as long (CI 0.95-1.08); anterior margin of median clypeal lobe straight to broadly convex, rounded laterally; pronotum dorsolaterally margin- ate but not sharply so; in lateral view mesonotum more steeply inclined than basal face of propodeum; petiole long and slender (PLI 0.46-0.57) with a distinct anterior peduncle (Figs. 6, 53); head densely punctulate with a subopaque to sublucid (not matte) appearance; standing pilosity abundant, fine, pre- dominantly pale silvery- white (not black). Size and color extremely variable (HW 1.39- 2.07), varying from unicolorous black (appendages lighter) to unicolorous orange-brown, with many intermediate and bicolored combinations. In popu- lations from Mesoamerica the gaster is typically black, or if paler (orange-brown) then it is usually accompanied by a similar light coloration of the mesosoma (and sometimes also the head). Taxonomic comments. The P. gracilis com- plex presents one of the more taxonomically chal- lenging problems in the genus Pseudomyrmex and the above treatment is by no means a final solution. The worker- and queen-based forms, newly syn- onymized under P. gracilis, fall within the bounds of the preceding diagnosis, but it is quite possible that my concept of this species will prove to be too broad. The types of P. dimidiatus, P. mexicanus and P. veliferus could not be located. They are judged to be junior synonyms on the basis of the original descriptions. The unique male holotype of P. volatilis is clearly a member of the P. gracilis group based on size (HW 1.48), mandibular dentition, pilosity, petiole shape, and shape of the parameres. In comparison with males of gracilis group species known to occur in Mexico, namely P. gracilis, P. major (see below), P. nigropilosusandP. opaciceps, the type specimen agrees best with P. gracilis. The concept of P. gracilis adopted above en- compasses an impressive amount of phenotypic variability. Collections from single regions often give the impression that this variation is distributed bimodally or multimodally , as more or less discrete morphs. For example, nest samples from Costa Rica can be segregated on the basis of worker morphology into (i) a large (HW > 1.80), usually lighter-colored form (with orange mesosoma, peti- ole, and postpetiole, and black head and gaster), (ii) a smaller, bicolored, usually more heavily infuscated form, and (iii) an all-black form of variable size. The first two are typically found in open or xeric habitats while the third is more common in closed forest, suggesting some ecotypic differentiation. Yet when large enough sample sizes are obtained all degrees of intermediacy in size and color are encountered, and the variation in color (less so size) can be seen among individuals (workers and alate queens) from the same nest. Thus, if there are ecotypes they do not appear to be reproductively isolated. Left unresolved after the establishment of the above synonymy is the relationship of P. gracilis to the following nominal taxa: P. alternans (Santschi), P. gracilis atrinodus (Santschi), P. gracilis argentinus (Santschi) and P. santschii (Enzmann). But the following deserves recognition as a distinct species: Pseudomyrmex major (Forel 1899:91), stat. nov. (syntype worker, Pinos Altos, Chihua- hua, Mexico (Buchan-Hepburn) (BMNH) (exam- ined); original combination: Pseudomyrma gracilis var. major). Workers of P. major can be distin- guished from those of P. gracilis by their emargin- ate median clypeal lobe, less distinct anterior pe- duncle of the petiole, and larger average size. Males of P. major have broadened fore-tarsal segments. P. major is confined to western Mexico, where it occurs sympatrically with P. gracilis without show- VOLUME 2, NUMBER 1 , 1993 157 ing signs of intergradation. Distribution and biology. Befitting its wide distribution (southern United States to Argentina and Brazil) and variable phenotype, P. gracilis can be found in a variety of habitats from mangroves and thorn scrub to rainforest. It is often particularly common in disturbed situations such as old fields, roadsides, and secondary forest. Nests are usually located in dead twigs or small branches, but there are a substantial number of records of colonies occupying swollen-thorn acacias in Central America (Mexico to Panama). In a few localities P. gracilis is a common acacia inhabitant and under these circumstances it may exhibit local adaptation and phenotypic differentiation (see also Wheeler 1942:107). For example, Janzen collected a series of specimens from Acacia gentlei in Belize (15 mi. S Santa Elena) which have somewhat distinctive morphology: the workers are large, dark, abun- dantly hairy, and possess rather short petioles (PLI 0.55), although none of these features is outside the total range of variation for the species. Janzen (1974:98) notes that the workers of this large black morph have atypically aggressive behavior. Given the kind of ecotypic variation to which P. gracilis is prone, it is not surprising to find a tendency of some populations to specialize on acacias. The ecology of this species is reminiscent of other animal spe- cies which show broad ecophenotypic variation, e.g. fish with trophic polymorphisms (Kornfield et al. 1982; Grudzien and Turner 1984; Sandlund et al. 1992). Pseudomyrmex hesperius Ward, sp. nov. (Fig. 4) Holotype worker. MEXICO Sinaloa: 15.9 mi. NE Concordia, Hwy. 40, 600m, 9.vi.l967, D. H. Janzen XVIII, ex Acacia hindsii (LACM). HW 0.66, HL 0.83, EL 0.36, PL 0.34, PH 0.26. Paratypes. Same data as holotype: series of 1 1 workers (BMNH, LACM, MCZC, MZSP, PSWC, USNM). Additional non-type material. MEXICO Sinaloa: 14 km. S Mazatlan, 18.vii.1965, R. R. Snelling, 15 workers (LACM, MCZC, PSWC). Worker measurements (n=6). HL 0.78-0.85, HW 0.65-0.69, MFC 0.028-0.043, CI 0.79-0.83, REL 0.43-0.46, REL2 0.54-0.57, OOI 0.86-1.15, VI 0.75-0.82, FCI 0.043-0.062, SI 0.48-0.51, SI2 0.87-0.93, FI0.41-0.45,PDI 0.84-0.95, MPI 0.053- 0.066,NI0.54-0.59,PLI0.73-0.77,PWI0.63-0.70, PPWI 1.41-1.56. Worker diagnosis. Small species (see above measurements) with elongate, subrectangular head and short eyes (REL 0.43-0.46, OI 0.61-0.65). Masticatory margin of mandible with five teeth, the fourth tooth (counting from the apex) separated by a gap of ca. 0.05 mm from the apicobasal tooth; MD8/MD9 0.70; third and fourth teeth small, contrasting with the large subapical and apical teeth (the latter ca. 0.032 and 0.055 mm in length, respec- tively) ; mesial tooth on basal margin situated slightly closer to apicobasal tooth than to proximal tooth (MD4/MD5 0.65); palp formula 5,3; median clypeal lobe short, its anterior margin straight to weakly convex, sharply rounded laterally; mini- mum distance between frontal carinae subequal to or less than basal scape width; frontal carinae diverging anteriorly and fusing with the antennal sclerites; pronotum laterally rounded, without hu- meral angles; in lateral profile the mesonotum and basal face of propodeum slightly inclined anteri- orly, separated by a well developed metanotal groove (Fig. 4); basal face of propodeum rounding into the longer declivitous face, the latter somewhat con- cave in profile; petiole short, apedunculate, shaped as in Fig. 4, with a prominent triangular antero ventral tooth; in dorsal view petiole very broad anteriorly (PWI3 0.59-0.62); postpetiole broader than long, its anteroventral process small and inconspicuous. Mandibles finely striate; head punctulate on a smooth shining background, punctulae separated by one to several diameters on upper half of head, becoming denser towards the clypeus; mesosoma sublucid, with weak punctulate-coriarious sculp- ture; petiole, postpetiole and gaster shining, with very fine piligerous punctures. Standing pilosity common but short (< 0.10 mm) on most parts of body, lacking on outer faces of tibiae. Appressed pubescence widely distributed, moderately dense on abdominal tergite IV. Dark brown; mandibles, appendages and fronto-clypeal complex tending towards a lighter brown. Taxonomic comments. This is a taxonomi- cally isolated species, not belonging to any of the 158 JOURNAL OF HYMENOPTERA RESEARCH nine major species groups of Pseudomyrmex (see Ward 1989).ThesalientfeaturesofP. hesperius are small size (HW < 0.72), reduced mandibular denti- tion and palp formula, short truncate median clypeal lobe, short eyes (especially obvious in lateral view, such that OI > 0.60), short apedunculate petiole with a broad attachment to the propodeum (PWI3 0.60), punctulate head sculpture, sublucid integu- ment, and short standing pilosity. Some of these traits are shared with two other Mesoamerican Pseudomyrmex, P. fervidus (F. Smith) and a re- lated undescribed species, but both of these are larger (HW > 0.70), with standing pilosity which is longer and more extensive (present on the outer faces of the tibiae). Biology. Although the type specimens of P. hesperius were collected from Acacia hindsii this species is not an obligate acacia inhabitant. The series from 14 km. south of Mazatlan was collected from dead branches of a woody plant, not Acacia (R. R. Snelling, pers. comm.). Pseudomyrmex ita (Forel 1906) stat. nov. (Fig. 2) Pseudomyrma sericea var. ita Forel 1906:230. Syntype workers, San Mateo, Costa Rica (P. Biolley) (MHNG) [Examined]. One syntype here designated LECTOTYPE. Pseudomyrma sericea var. acaciarum Wheeler 1942:176. Syntype workers, Tumba Muerta Road, Panama (W. M. Wheeler) (LACM, MCZC) [Examined] Syn. nov. Pseudomyrma sericea var. acaciorum Enzmann 1945:90. Syntype workers, Tumba Muerta Road, Panama (W. M. Wheeler) (MCZC) [Examined] [Objective synonym of Pseudomyrma sericea var. acaciarum Wheeler; Brown 1949:43]. Pseudomyrmex sericeus ita (Forel); Kempf 1972:223. Worker diagnosis. A medium-sized member (HW ca. 0.75-0.98) of the P. sericeus group, with large elongate eyes (REL 0.65), convex median clypeal lobe, subcontiguous frontal carinae (MFC 0.02), and palp formula of 6,4. Head longer than broad (CI 0.85). Basal face of propodeum shorter than declivitous face and meeting the latter at an angle. Petiole short, high (PLI > 1.00), with sharp dorsolateral margins; in profile anterior and dorsal faces of petiole weakly differentiated, rounding sharply into the vertical posterior face (Fig. 2). Body with fine punctulate-coriarious sculpture, opaque. Standing pilosity very sparse; a pair of stout setae present on the pronotal humeri, petiole, and postpetiole. Dark brown-black, with lighter brown maculation variably present on the pronotum, petiole, postpetiole, fronto-clypeal complex, and appendages. Taxonomic comments. This is one of several species originally described as "varieties" of P. sericeus (Mayr). Workers of P. ita can be distin- guished from those of P. sericeus by the angulate shape of their petiole, especially in lateral view (Fig. 2); the petiole of P. sericeus is subtriangular in profile, with more gently rounded edges. Distribution and biology. P. ita occurs from Mexico to Colombia, and typically inhabits dead twigs or branches of various woody plants. It has been collected from thorns of Acacia cornigera in Mexico and A. collinsii in Costa Rica and Panama. Pseudomyrmex kuenckeli (Emery 1890) (Fig. 3) Pseudomyrma kuenckeli Emery 1890:62. Syntype workers, queens, Alajuela, Costa Rica (A. Alfaro) (MCSN) [Examined]. Pseudomyrmakuenckelivar. dichroaForel 1904:41. Syntype workers, Dibulla, Colombia (A. Forel) (AMNH, BMNH, MCSN, MHNG, NHMB, USNM) [Examined] [Synonymy by Kempf 1961:402]. Pseudomyrma kuenckeli var. bierigi Santschi 1932:412. Holotype worker, Juan Diaz, Panama (A. Bierig) (NHMB) [Examined] [Synonymy by Kempf 1961:402]. Pseudomyrma crenulata Enzmann 1945:84. Holo- type worker, "Guernavaca", Mexico (not in MCZC) [Not examined; but other P. kuenckeli workers in the MCZC from Cuernavaca, Mexico (Wheeler) evidently represent the source series] [Synonymy by Kempf 1961:402]. Pseudomyrmex kuenckeli (Emery); Kusnezov 1953:214. VOLUME 2, NUMBER 1 , 1 993 159 Worker diagnosis. A member of the P. viduus group, easily recognized by the shiny broad head (CI 1.12), short eyes (REL 0.46), flattened mesosoma, blocky petiole, and abundant pilosity (Fig. 3). For further description see Kempf (1961:402). Distribution and biology. This is a widely distributed but generally uncommon species, found from Mexico to Argentina and Brazil. P. kuenckeli appears to have a preference for nesting in large dead branches, in somewhat open or seasonally dry forest. Its association with ant acacias is sporadic at best and based upon two records from Costa Rica: Emery (1891 : 168) reported a single specimen col- lected by Alfaro from a swollen-thorn acacia, and Menozzi (1927b) recorded a collection by H. Schmidt from Acacia "spadicigera" (probably a misidentification of A. collinsii) near San Jose. Pseudomyrmex nigropilosus (Emery 1 890) (Fig. 7) PseudomyrmanigropilosaEmery 1890:62. Syntype workers, Liberia, Costa Rica (A. Alfaro) (MCSN, MHNG) [Examined]. Pseudomyrmex nigropilosus (Emery); Kempf 1958:453. Worker diagnosis. With the traits of the P. gracilis group (see couplet 6 of key) and the follow- ing more specific features. Head longer than broad (CI 0.84-0.90); anterior margin of median clypeal lobe convex, conspicuously protruding; dorsolat- eral margination of pronotum usually blunt; mesonotum more steeply inclined than basal face of propodeum; petiole relatively robust (PLI 0.69- 0.77) with a short anterior peduncle (Fig. 7, 53); head and mesosoma densely punctulate to coriarious-imbricate, and subopaque; standing pi- losity conspicuous on most of the body including the outer faces of the tibiae, consisting largely of black hairs, those on the petiole and propodeum long (> 0.20 mm) and curved. Color varying from concolorous orange-brown to bicolored orange and black to (western Mexico) predominantly black with orange mottling on the head, mesosoma, and appendages. Taxonomic comments. Among the Pseudomyrmex species recorded from swollen-thorn acacias, P. nigropilosus is easily identified by its elongate eyes and head (REL 0.55-0.59, CI 0.84- 0.90), short petiole (PLI 0.69-0.77), and conspicu- ous black pilosity (Fig. 7). Kempf (1958) provides further descriptive details. Distribution and biology. P. nigropilosus is found from Nayarit, western Mexico to Guanacaste Province, Costa Rica, and is restricted to nesting in swollen-thorn acacias (including Acacia collinsii, A. cornigera and A. hindsii). It is a member of the P. gracilis group and therefore not closely related to the principal group of acacia-ants (P.ferrugineus group) . Janzen ( 1 975) points out that P. nigropilosus is essentially a parasite of the Pseudomyrmexl Aca- cia mutualism. It occupies abandoned or otherwise uninhabited plants and reaps the benefits of this association without protecting the acacia from her- bivores or competing plants. Additional informa- tion about the ecology of this species is given in Janzen (1975). Pseudomyrmex opaciceps Ward, sp. nov. (Fig. 5) Holotype worker. GUATEMALA Retalhuleu: Puente Samala, 3.8 mi. NE San Felipe, 24.vii. 1966, D. H. Janzen W006724966 (LACM). HW 1.43, HL 1.42, EL 0.85, PL 0.89, PH 0.39. Paratypes, Series of 11 workers with same data as holotype; large series of ca. 60 workers and 10 males with the same locality and collector as holotype but the following dates and collection numbers: 18.vii.1966 M002718966 (possibly mis- labelled - see below), 18.vii.1966 W002718966, 18.vii.1966 W004718966, 18.vii.1966 W0057 18966 (possibly mis-labelled - see below), 23.vii.1966 W002723966, 24.vii.1966 W001724966, 24.vii.1966 W003724966 (BMNH, LACM, MCZC, MZSP, PSWC, UCDC, U.SNM). Additional non-type material. Series of work- ers, queens, and males from six additional locali- ties. MEXICO Chiapas: 94.5 mi. SE Tonola (D. H. Janzen). GUATEMALA Retalhuleu: 2 mi.N Puente Samala, 3.8 mi. NE San Felipe (D. H. Janzen); 3 mi. N Puente Samala, 3.8 mi. NE San Felipe (D. H. Janzen); 5 mi. W Retalhuleu, Hwy. CA-2 at Rio Nil 160 JOURNAL OF HYMENOPTERA RESEARCH (D. H. Janzen); Guatemala: Ciudad de Guatemala (D. H. Janzen). EL SALVADOR La Libertad: Quezaltepeque (M. Irwin & D. Cavagnaro) (LACM, MCZC, PSWC). Worker measurements (n=14). HL 1.30-1.42, HW 1.33-1.43, MFC 0.040-0.058, CI 0.99-1.04, REL 0.57-0.61, REL2 0.56-0.61, OOI 0.14-0.68, VI 0.65-0.71, FCI 0.029-0.042, SI 0.46-0.50, SI2 0.77-0.88,FI0.36-0.39,PDIL12-1.37,MPI 0.059- 0.076, NI 0.65-0.70, PLI 0.42-0.47, PWI 0.38-0.43, PPWI 0.92-1. 16. Worker diagnosis. With the traits of the P. gracilis group (see couplet 6 of key) and the follow- ing more specific features. Head about as broad as long; anterior margin of median clypeallobe straight to weakly convex; pronotum with blunt dorsolat- eral margination ; mesonotum more steeply inclined than basal face of propodeum; petiole long and slender (see PLI and PWI values) with a distinct anterior peduncle (Fig. 6); head densely punctulate- coriarious and matte; standing pilosity abundant, pale silvery-white, not black. Color: head and mesosoma dark brown to black, mandibles and appendages lighter brown; petiole, postpetiole and gaster a contrasting pale luteous brown or orange- brown. Portions of the fronto-clypeal complex, malar area, and mandibles may also be luteous brown. Taxonomic comments. This species is distin- guished from the closely related and sympatric P. gracilis by a modest but consistent difference in head sculpture. In workers and queens of P. opaciceps the punctulate-coriarious sculpture and associated dense pubescence obscure the sheen of the head, producing a matte appearance under soft light, while in P. gracilis the head remains at least weakly shining. In addition the workers and queens of P. opaciceps average smaller in size than those of P. gracilis and they have a more slender petiole (PLI < 0.48; see Figs. 5, 6, 53). Finally, P. opaciceps has a distinctive and largely invariant color pattern: the pale yellow or orange-brown petiole, postpetiole and gaster contrast with the much darker head and mesosoma. This is not observed in Central Ameri- can P. gracilis, although a similar color pattern occurs in some Colombian populations of P. gracilis, and it also seen in some individuals of the more distantly related South American species P. venustus (F. Smith). Among the P. opaciceps paratypes in LACM, the pinned specimens with Janzen collection num- bers M0027 1 8966 and W0057 1 8966 appear to have been mis-labelled. In the Janzen alcohol collection samples M0027 18966 and W0057 18966 contain colony series of two quite different species (in the P.ferrugineus andP. pallidus groups, respectively); but there are two other alcohol samples from the same date and locality (W0027 18966 and W0047 18966) which are of P. opaciceps. I con- clude that a frame-shift occurred in the process of labelling the pinned series of specimens, producing the labelling error (this has happened to a substan- tial number of P. ferrugineus group collections - see "Materials and Methods" section). The remain- ing paratype (and non-type) material of P. opaciceps appears to be correctly labelled. Biology. P. opaciceps is evidently a generalist twig-nesting Pseudomyrmex, but Janzen also col- lected it from an Acacia cornigera tree overgrown by vines and unoccupied by the P. ferrugineus group (5 mi. W Retalhuleu, Guatemala, collection numbers M010714966-A and M010716966-D). Pseudomyrmex reconditus Ward, sp. nov. (Fig. 8) Holotype worfcer NICARAGUA, Madriz: 2.0 mi. S Honduran border,Hwy 1, 840m, 29.vii.1967, mi. 8207.2, D. H. Janzen, ex Acacia collinsii (LACM). Paratypes. One worker, one dealate queen, same data as holotype (LACM). Holotype andparatype worker measurements. HL 1.54, 1.44, HW 1.54, 1.47, MFC 0.071, 0.056, EL 0.93, 0.86, PL 0.88, 0.78, PH 0.57, 0.47, CI 1.00, 1.02, OI 0.52, 0.52, REL 0.61, 0.59, REL2 0.61, 0.58, OOI -0.01, -0.01, VI 0.73, 0.71, FCI 0.046, 0.038, SI 0.47, 0.47, FI 0.44, 0.39, PDI 1.21, 1.12, MPI 0.067, 0.061, NI 0.62, 0.64, PLI 0.64, 0.60, PWI 0.57, 0.53, PPWI 1.40, 1.25. Paratype queen measurements. HL 1 .79, HW 1.66, MFC 0.065, EL 1.02, PL 1.21, PH 0.75, CI 0.92, OI 0.5 1, REL 0.57, REL2 0.62, OOI 0.22, VI 0.79,FCI 0.039, SI 0.45, FI 0.46, NI 0.61, PLI 0.62, PWI 0.61, PPWI 1.53. Worker diagnosis. With the traits of the P. VOLUME 2, NUMBER 1 , 1993 161 gracilis group (see couplet 6 of key) and the follow- ing more specific features. Head as broad as long; anterior margin of median clypeal lobe slightly convex, rounded laterally; pronotum with blunt dorsolateral margination; mesonotum more steeply inclined than basal face of propodeum; petiole of moderate length, high (PLI 0.60-0.64), with a dis- tinct anterior peduncle but without a well devel- oped anteroventral tooth (Figs. 8, 53), and lacking sharp dorsolateral margination; postpetiole notably broader than long. Mandibles weakly striolate, sublucid, becoming shagreened basally; head and mesosoma densely but finely punctulate-coriarious to coriarious-imbricate, subopaque; petiole, postpetiole, and gaster with fine piligerous punc- tures, obscured from view by the associated pubes- cence. Standing pilosity only moderately dense but with some apparent loss due to abrasion of the type specimens; hairs mostly black, not silvery-white, present on the head, mesosoma dorsum, petiole, and postpetiole; at least some moderately long (0.23-0.27 mm) hairs on the propodeum and peti- ole; one or two short hairs present on the outer faces of the meso- and meta-tibiae, the others possibly worn off; fine appressed golden pubescence present on most of the body. Head and mesosoma black, gaster dark brown, petiole and postpetiole orange; appendages brown, with orange flecking on the legs. Taxonomic comments. This species is known only from the types. It is readily distinguished from all other acacia-associated species in the P. gracilis group by the combination of broad head (see CI values), robust petiole (PLI 0.60-0.64), and black pilosity. P. reconditus is similar to an undescribed Pseudomyrmex species collected from Tachigali in northern Peru (P. sp. PSW-35) but the latter has a shorter petiole, more extensive silvery-white pilos- ity and pubescence, and is all black in color. Biology. The type collection from Acacia collinsii is the only record. A single worker of P. nigropilosus occurred in the same alcohol vial as the workers and queen of P. reconditus. It remains to be confirmed that P. reconditus is confined to nesting in swollen-thorn acacias. Pseudomyrmex simulans Kempf 1958:459. Holo- type worker, Tumba Muerta Road, Panama (W. M. Wheeler) (MCZC) [Examined]. Worker diagnosis. With the traits of the P. gracilis group (see couplet 6 of key) and the follow- ing more specific features. Head longer than broad (CI 0.86-0.90); anterior margin of median clypeal lobe straight to broadly convex, rounded laterally; pronotum with sharp dorsolateral margination; mesonotum more steeply inclined than basal face of propodeum; petiole relatively short and high (PLI 0.61-0.66), with a distinct anterior peduncle (Figs. 9, 53), and with moderate dorsolateral mar- gination; head and mesosoma finely punctulate- coriarious to coriarious-imbricate, subopaque; standing pilosity rather short, pale and inconspicu- ous, present on the mesosoma dorsum and (usually) outer surfaces of the tibiae, but sometimes lacking or worn off on the latter; fine appressed pubescence on most of body; dark brown-black in color, distal portions of appendages lighter; mandibles luteous. Taxonomic comments. This curious species bears a superficial resemblance to the obligate acacia-ants (P. ferrugineus group), although its affinities to other/ 3 , gracilis group species are clear from eye size, pilosity, palp formula, mesosomal structure, and male genitalia. P. simulans can be recognized by the combination of elongate eyes (REL 0.52-0.55), short petiole (PLI 0.61-0.66), short inconspicuous pilosity, and black color. Distribution and biology. P. simulans is known only from a few collections, all from swollen-thorn acacias (A. collinsii), in Panama (Canal Zone and the provinces of Veraguas, Los Santos and Panama). Nothing has been published about its nesting biol- ogy or behavior, but Janzen's field notes indicate that the workers are more timid than those of the P. ferrugineus group. One might surmise that its hab- its are similar to those of P. nigropilosus, although the two species do not appear to be one another's closest relatives (Ward 1991). Pseudomyrmex subtilissimus (Emery 1890) Pseudomyrmex simulans Kempf 1958 (Fig. 9) Pseudomyrma subtilissima Emery 1890:65. Lecto- type worker, Alajuela, Costa Rica (Alfaro) 162 JOURNAL OF HYMENOPTERA RESEARCH (MCSN) [Examined]. Pseudomyrmex subtilissimus (Emery 1890);Kempf 1972:224. Worker diagnosis. A member of the P. subtilissimus group, and immediately distinguish- able from all other acacia-associated Pseudomyrmex by its small size (HW < 0.60), elongate head (CI < 0.66), apedunculate petiole, and scarcity of stand- ing pilosity. See Ward (1989:432) for further dis- cussion of this species. Distribution and biology. P. subtilissimus has been collected only in Nicaragua and Costa Rica. What little is known about its biology suggests that it is a timid, non-protective species living in the thorns of Acacia plants occupied by (declining?) colonies of P. flavicornis. PHYLOGENY AND BIOGEOGRAPHY OF THE OBLIGATE ACACIA- ANTS The 47-character data set used for cladistic analy- sis of the P. ferrugineus group is given in Table 2. Implicit enumeration by Hennig86, using the ie* command, yielded a single most parsimonious tree of length 73, consistency index 0.86 (0.84 exclud- ing autapomorphies of ingroup species) (Fig. 73). This tree has an unresolved trifurcation involving five Pseudomyrmex species: ferrugineus, janzeni, and (flavicornis + (mixtecus + veneficus)). These five species together constitute what may be termed the P. ferrugineus complex. It is allied to the pair of sister species, P. spinicola and P. satanicus. The sister group of these seven species is the isolated and autapomorphous P. peperi. Finally, P. nigrocinctus and P. particeps make up a basal pair of species with relatively unspecialized morphol- ogy. Separate analyses of worker-, queen-, and male- based data sets produced trees in substantial agree- ment with these findings and largely congruent with one another (Figs. 74-76). This indicates that some confidence can be attached to the main fea- tures of the cladogram, and that homoplasy in worker and queen morphology possibly due to parallel selection pressures during diffuse coevolu- tion of the ant/acacia interaction (see below) has not been so rampant as to obscure all evidence of relationship, since both castes point to a cladistic pattern similar to that derived from male morphol- ogy (primarily male genital characters). Disagree- ment revolves around the position of taxa within the P. ferrugineus complex. Worker morphology sug- gests that P. mixtecus is more closely related to P. flavicornis than to P. veneficus. The male character set supports a (P. mixtecus + P. veneficus) pairing and is uninformative about other relationships within the P. ferrugineus complex. The queen-based tree is identical in topology to that based on all characters, i.e. it supports (P. flavicornis + (P. mixtecus + P. veneficus)) but does not resolve relationships among P. ferrugineus, P. janzeni, and the foregoing trio. The inferred phylogeny of the P. ferrugineus group (Fig. 73) suggests that speciation has oc- curred primarily as a consequence of geographical isolation. Of the three pairs of sister species, two (P. nigrocinctus + P. particeps, P. mixtecus + P. veneficus) are composed of allopatric species (Figs. 69, 72), while the ranges of the third pair (P. spinicola and P. satanicus) are more or less con- tiguous (Fig. 68). The trio of species comprising (P. flavicornis + (P. mixtecus + P. veneficus)) also have entirely non-overlapping distributions, and they point to the importance of geographical barriers in southwestern Mexico to speciation in this complex (Fig. 69). This is also indicated by the distributions of P. ferrugineus and P. janzeni, the latter an allopatric isolate in western Mexico (Fig. 70), al- though it should be noted that the cladistic analysis did not confirm a sister group relationship between these two phenetically similar species. At higher levels in the cladogram there is some geographical overlap between taxa, but dispersal has not been so extensive as to obliterate all evidence of vicariance. Within the P. ferrugineus complex, for example, P. flavicornis and relatives are largely confined to the Pacific slopes of Mesoamerica in contrast to the more eastern distribution of P. ferrugineus (Figs. 69-70). The P. ferrugineus complex itself is centred in northern Central America, with only one species (P. flavicornis) occurring south of Honduras, as far as Costa Rica in this case, while its sister group (P. spinicola and P. satanicus) occurs primarily south of Honduras and extends all the way to northern Colombia (Fig. 68). This suggests an historical barrier somewhere in the region of present day VOLUME 2, NUMBER 1, 1993 163 Honduras or Nicaragua which split these two clades. The most basal divisions within the P. ferrugineus group involve much more extensive geographical overlap, making any historical inferences difficult. The distributions of the species P. peperi and P. nigrocinctus are consistent with an origin and early diversification of the P. ferrugineus group in either northern or central Mesoamerica. The timeframe for this is unknown but presumably occurred prior to the formation of the Panamanian land bridge (i.e. before early Pliocene or late Miocene). Early diver- sification in the group may have been encouraged by the presence of an island archipelago in the region (Donnelly 1992). Finally, we come to the question of whether the phylogenies of the acacia-ants and their host aca- cias are congruent. A phylogeny of the swollen- thorn acacias is not available but Janzen's (1974) revision contains some relevant information. Janzen (1974) concluded that the Central American swol- len-thorn acacias are polyphyletic, i.e. that myrmecophy tism arose more than once or that non- myrmecophytic acacia species independently ac- quired myrmecophytic traits through hybridiza- tion. He also noted (Janzen 1966) that individual species of acacia can be associated with more than one Pseudomyrmex species and vice versa. None of this leads one to expect a pattern of co-speciation, and mapping known host associations on the Pseudomyrmex cladogram (Fig. 73) confirms the opportunistic nature of the interaction. It seems that most species in the Pseudomyrmex ferrugineus group occupy any swollen-thorn acacia species available to them. On the other hand, the possibility of locally non-random associations between ants and available plants, perhaps mediated by compe- tition, deserves investigation. Three species of acacia-ants, P. janzeni, P. particeps and P. satanicus, are confined to a single acacia species (A. hindsii, A. allenii and A. melanoceras, respectively), the former (P. janzeni) almost certainly because of its limited geographical distribution but the last two because of their appar- ent specialization on the acacia or the forest habitat to which it is restricted. Populations of other swol- len-thorn acacia species occur within the probable dispersal ranges of alate queens of P. particeps and P. satanicus but are apparently not colonized. These two host-specific Pseudomyrmex have the smallest ranges of any members of the P. ferrugineus group and are clearly the most endangered. CONCLUDING REMARKS Table 2. Data set used for cladistic analysis of the_Pseudomyrmex ferrugineus group. P. fervidus served as outgroup (see text)."?" signifies polymorphism or ambiguity in expression of the character state. Characters 12, 13 and 16 were considered unordered. 1 11 21 31 41 fervidus 0000000000 7700000001 7000700000 0000000000 0000070 nigrocinctus 0001000001 1021000010 0011001000 0001110010 1001101 particeps 0001000001 1021000011 0010001100 0001110010 1001101 peperi 0011001121 2210020011 0011011001 0002100111 1112212 spinicola 1100101111 010010001? 1110701110 0112100011 1212221 satanicus 1110111111 0100100011 1210201110 0112100011 1212221 ferrugineus 0000001111 0100001011 1110201010 0102101111 1222221 janzeni 0000001111 0100001010 1110201010 0102101111 1222221 flavicornis 0000001111 0100011012 1110201010 0102101111 1222221 mixtecus 0000001111 0100011012 1111111010 0102101121 1222221 veneficus 0000001111 0100001112 1111111010 0102101121 1222221 164 JOURNAL OF HYMENOPTERA RESEARCH 73 outgroup 4 13 1431 36 nil I all characters (length 73 ci 0.86) 7 8 9 12 34 40 42 43 44 45 46 I I I I I I I I I I I 3 4 9 11 12 13 16 24 26 30 38 47 i B i i i i i n i i i 3 6 22 11 21 22252529324246 I I I I I I I I I 1 25 152833 I I I I I I 17 37 38 43 I I I I 1620 24252639 || 16 18 =H I I " I nigrocinctus particeps al peperi satanicus spinicola ferrugineus janzeni flavicornis ntixtecus veneficus cr ge gl hi me al cl cr ch cl co cr ge gl hi ma sp hi cl cr hi cl hi cl hi 74 worker characters (length 29 ci 0.89) 75 queen characters (length 33 ci 0.75) 76 male characters (length 28 ci 0.96) Figs 73-76. Phylogenetic relationships of the obligate acacia-ants, Pseudomyrmex ferrugineus group. 73: cladogram based on the entire 47-character data set (Table 2), with character state changes indicated and with host plant associations listed for each species. Solid bars: unique forward changes; hatched bars: homoplasious forward changes; open bars: reversals. There are alternative, equally parsimonious reconstructions of character state change for characters 4, 12, 16, 38 and 46. By reference to other Pseudomyrmex species, most changes occurring between the outgroup (P.fervidus) and the ingroup (i.e. changes in characters 10, 19, 23. ..47) are probably synapomorphies of the latter, but one character state (27.0) appears to be aderived feature of P.fervidus. The following abbreviations are used for host plants: al = Acacia allenii, ch = A. chiapensis, cl = Acacia collinsii, co = A. cooki and A. janzenii, cr = A. cornigera, ge = A. gentlei, gl = A. globulifera, hi = A.hindsii, ma = A. mayana, me = A. melanoceras, sp = A. sphaerocephala. 74-76: cladograms based on the worker, queen and male character sets, respectively. VOLUME 2, NUMBER 1 , 1 993 165 This systematic study of Pseudomyrmex ants associated with swollen-thorn acacias in Central America demonstrates that the primary group of obligate acacia-ants (the P. ferrugineus group) is monophyletic and comprises 1 species. Four addi- tional unrelated Pseudomyrmex species, from two other species groups, have become secondary spe- cialists on the acacias. These latter species appear to be parasites or commensals but little is known about their biology (except P. nigropilosus). These 14 specialists are joined by at least six generalist twig-nesting Pseudomyrmex which occasionally colonize acacia thorns. The well known mutualism between ants and Central American acacias applies with certainty only to members of the P. ferrugineus group and their associated plants. Within this group experi- mental evidence of a mutualism is available only for the P. ferrugineus x A. cornigera interaction (Janzen 1966, 1967b), although the biology and behavior of the other nine species of ants suggest that they also provide important protection to their host acacias under most conditions. Cladistic analy- sis of the P. ferrugineus group, coupled with a consideration of host plant associations, indicates a pattern of diffuse coevolution, not one-on-one cospeciation (see also Janzen 1 966). It seems likely that the original obligate acacia-ant (the common ancestor of the P. ferrugineus group) underwent coevolution with its acacia host, but since then speciation and diversification of the two groups have been decoupled the swollen-thorn acacias are apparently even polyphyletic (Janzen 1974) and there has been much opportunistic pairing of ants and plants. Such liberal sharing of partners has presumably made the association susceptible to invasion by other Pseudomyrmex and Acacia lin- eages. At the same time the key features of the system absolute dependence of ants in the P. ferrugineus group on acacia plants, the reliance of at least some (probably most) of the swollen-thorn acacia spe- cies on ants for normal growth and reproduction, and the suite of mutually beneficial traits exhibited by both partners mark this as one of the more impressive insect/plant mutualisms known. ACKNOWLEDGMENTS I thank the following persons for access to collec- tions under their care: J. Newlin (ANSP), B. Bolton (BMNH), M. A. Tenorio (CASC), H. A. Hespenheide (CHAH), R. Ayala (EBCC), F. Fernandez (FFIC), D. Quintero Arias (GBFM), A. Solis (INBC), J. T. Longino (JTLC), R. R. Snelling (LACM; also old loans to D. H. Janzen from AMNH, CISC, CUIC, GCWC, INHS, KSUC, MCZC, SEMC, UCDC, UCRC and USNM, now returned to their original locations), R. Poggi (MCSN), S. Cover (MCZC), C. Besuchet(MHNG), J. C. Weulersse (MNHN), C. R. F. Brandao (MZSP), M. Brancucci (NHMB), M. Fisher (NHMV), D. R. Smith (USNM), W. P.MacKay (WPMC), F. Koch (ZMHB), O. Lumholdt (ZMUC), D. R. Abraham (ZMUH) and E. Diller (ZSMC). Special tribute should be paid to Dan Janzen whose prodigious efforts in the field yielded a collection of acacia-ants unprecedented in size and scope, together with much valuable biological information. I am particularly grateful to Jack Longino and Roy Snelling who facilitated my study of the Janzen collection in LACM. 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Errata for: Ward, P. S. 1993. Systematic studies on Pseudomyrmex acacia-ants. J. Hym. Res. 2:117-168. Due to a printer's error all " ^ ", " <, " and " ~ " signs in this paper were replaced by blanks (although these symbols were present in the page proof), resulting in a significant loss of information. The affected text follows. p. 121, column 2, line 30 "PLI2 ^ 0.77" p. 121, column 2, line 45 "worker PLI ^ 0.71, queen PLI St 0.64" p. 122, column 1, line 36 "HW < 0.85" p. 122, column 1, line 37 "HW ^ 0.85" p. 122, column 1, line 41 "PL/HW k 0.71" p. 122, column 2, lines 8-9 "CI St 0.94 and/or HW 5: 0.96" p. 122, column 2, line 15 "SL/HL 5: 0.22" p. 122, column 2, line 16 "SL/HL 0.21" p. 130, line 33 "CI 1.12" p. 130, line 35 "CI 0.80" p. 132, line 40 "SL/HL ^ 0.21" p. 132, line 42 "SL/HL ^ 0.22" p. 133, lines 4-5 "CI 5: 0.94 and/or HW Ss 0.96" p. 133, column 1, line 8 "MD8/MD9 0.70" p. 133, column 1, line 11 "MD4/MD5 0.74" p. 135, column 2, line 4 "worker REL ^ 0.50, queen REL ^ 0.48" p. 135, column 2, lines 5-6 "worker PLI 0.71, queen PLI ^ 0.63" p. 135, column 2, lines 29-30 "queen PLI 0.65, queen PL/HL 0.49" p. 145, column 1, lines 26-27 "REL 0.45, REL2 < 0.56, EL/LHT ^ 0.61" p. 145, column 1, line 30 "FCI 0.055" p. 145, column 2, lines 7-8 "worker PWI3 ^ 0.50, worker PPWI s 1.30" p. 146, column 2, line 10 "CI 0.61" p. 146, column 2, line 12 "LHT/HW 1.12" p. 152, column 2, lines 14-15 "(^ 0.10 mm)" p. 155, column 1, line 20 "REL 0.66" p. 157, column 1, lines 20-21 "PLI 0.55" p. 157, column 2, line 12 "MD8/MD9 0.70" p. 157, column 2, line 17 "MD4/MD5 0.65" p. 158, column 1, lines 7-8 "PWI3 0.60" p. 158, column 1, line 41 "REL 0.65" p. 158, column 1, lines 42-43 "MFC 0.02" p. 158, column 1, line 44 "CI 0.85" p. 159, column 1, line 3 "CI 1.12" Another printing error resulted in the loss of data in column 31 of Table 2 (p. 163): Pseudomyrmex nigroclnctus and P. particeps should be coded "1", not "0", for character 31. Other corrections: p. 121, column 1, line 41 p. 131, line 34 For "public domain software" read "Shareware software" For "Figs. 10, 34" read "Figs. 11, 34"