Bol. Mus. Nac. Hist. Nat. Parag. Vol. 14 (1-2), Setiembre 2002, pp. 1 - 18 THE GENUS PACHYCONDYLA (HYMENOPTERA: FORMICIDAE) IN PARAGUAY ALEXANDER L. WILD Department of Entomology, University of California, Davis, Davis, CA 95616. e-mail: [email protected] Abstract.- Eleven species of the genus Pachycondyla are reported from Paraguay, four of which are new records for the country. An illustrated key to the workers of the species is provided, along with diagnoses, distri- bution data, taxonomic notes and natural history information for each of the species. Resumen.- Se registran once especies del género Pachycondyla en Paraguay, cuatro de ellas son nuevos registros para el país. Se proporciona una clave ilustrada para las obreras de las especies, junto con las diagnosis, datos de distribución, notas taxonómicas e información de historia natural para cada una de las especies. The genus Pachycondyla F. Smith 1858 is wood, dead branches, plant cavities, and epi- a large group of ants in the subfamily phytes (Leal and Oliveira 1995, Longino 2002, Ponerinae. There are around 200 described Lucas et al 2002, Trunzer et al 1998, Wheeler species worldwide, mostly known from the 1942, Wild pers obs.) tropics and sub-tropics (Bolton 1995.) The The taxonomic history of the genus reflects species of Pachycondyla are diverse in their its tremendous diversity. Until recently, these morphology and their behavior, ranging from ants had been placed in several genera. Brown cryptobiotic leaf litter inhabitants to large, ag- (in Bolton 1994, see also Brown 1973) brought gressive epigaeic and arboreal ants. Where they them into synonymy with Pachycondyla. The are present, many species are abundant and following list provides the former classifica- conspicuous insects. This study presents the tion for the species known from Paraguay, con- first catalogue of the Paraguayan sistent with how they appear in Kempf’s (1972) Pachycondyla, along with a key for identifica- “Catálogo abreviado das formigas da Região tion of species based on the worker caste. Neotropical” and the addendum by Brandão The larger species of Pachycondyla, espe- (1991): cially P. striata F. Smith 1858 and P. villosa (Fabricius 1804), are easily recognized by most Neoponera Emery 1901 Paraguayan farmers as the “tahyí hû pukú.” crenata (Roger 1861) These ants are known for their size, the pug- obscuricornis (Emery 1890a) nacity with which they defend their nests, and cf. obscuricornis their painful stings. villosa (Fabricius 1804) Most species of Pachycondyla appear to be Pachycondyla F. Smith 1858 generalist scavengers and predators of crassinoda (Latreille 1802) arthropods, which they subdue with venom harpax (Fabricius 1804) (Orivel and Dejean 2001). At least one group striata F. Smith 1858 has become specialized as termite predators Termitopone Wheeler 1936 (Mill 1984, Leal and Oliveira 1995). The nest- commutata (Roger 1860) ing and social biology of Pachycondyla is vari- marginata (Roger 1861) able. They live in colonies of a few dozen to a Trachymesopus Emery 1911 few thousand workers and nest in a variety of lunaris (Emery 1896) conditions, including soil, leaf litter, rotting stigma (Fabricius 1804) 2 BOL. MUS. NAC. HIST. NAT. PARAG. VOL. 14 (1-2) 2 1 3 Figs. 1-3. Schematic figures of Pachycondyla villosa, showing characters and measurements referred to in the text. 1) Frontal view of head; 2) lateral view of whole body, with legs beyond coxae and antenna beyond scape removed; 3) dorsal view of mesosoma and petiole. cl = clypeus, cx = coxa, e = eye, fc = frontal carina, fl = frontal lobe, HL = head length, HW = head width, mb = mandible, ms = metanotal suture, msp = mesopleuron, mtp = metapleuron, NL = length of petiolar node, NW = width of petiolar node, pd = propodeum, pg = pygidium, pn = pronotum, ps = propodeal spiracle, pt = petiolar node, PW = pronotal width, sc = antennal scape, SL = scape length, t = tergite, WL = weber length. It is not clear that Pachycondyla forms a Workers and queens of Pachycondyla in monophyletic group, even following the exten- Paraguay can be recognized on the basis of the sive synonomy. In particular, some of the small following characters: Mandibles triangular, cryptobiotic genera such as Hypoponera with at least 6 teeth (usually more) on the inner Santschi 1938 may have emerged from within margin. When the mandibles are closed, the Pachycondyla. Detailed phylogenetic work is inner margins in frontal view reach the clypeus needed to resolve this issue. It consequently (Fig. 1). Frontal lobes are close together on bears noting that the taxonomy may change the front of the head such that they are nearly once such work is completed. touching (Fig. 1). The hind legs each have two SETIEMBRE 2002 THE GENUS PACHYCONDYLA IN PARAGUAY 3 4 5 Figs. 4-5. Worker petiole, oblique rear view. 4) P. cf. obscuricornis; 5) P. obscuricornis. apical tibial spurs, one simple and one pecti- key and the text. The terminology is largely as nate. used by Bolton (1994). Bolton (1994) and Hölldobler and Wilson Distributional data: Species ranges were (1990) provide keys that are sufficient for ge- taken from Kempf (1972), Brandão (1991), and nus-level identification of Pachycondyla. Brown (unpublished manuscript.) There are no published keys to New World Measurements: Both size and allometry are Pachycondyla at the species level that reflect consistent and useful in separating some of the the current taxonomy. The late W. L. Brown species. For each species, I took the following had been working on Pachycondyla and left a measurements on the maximum number of useful manuscript key, but it remains unpub- available worker specimens, up to 8 individu- lished. Partial keys may be found in Kempf als. Schematics of the measurements are pro- (1961) and Kempf (1964). vided in Figures 1-3. All measurements are in millimeters. METHODS Nomenclature: I use the names given in Head width (HW)- the maximum width Bolton (1995), which to the best of my knowl- of the head in frontal view, posterior edge is the most current taxonomy for the Para- to and not including the eyes. guayan species. Since taxonomic revisionary Head length (HL)- in frontal view, from work is best carried out considering the full the maximum posterior extention of variation of a taxon over the whole of its geo- the head to the anterior clypeal mar- graphic range, and since this is a regional work gin. restricted to the Paraguayan fauna, I have in- Scape length (SL)- the length of the an- tentionally refrained from introducing taxo- tennal scape, not including the basal nomic changes, even in instances where I feel condyle. such change is probably warranted. I discuss Weber length (WL)- the distance from these instances in the species synopses. the anterior face of the pronotum to Key characters: Figures 1-3 illustrate the the maximum posterior extension of external anatomical features referred to in the 4 BOL. MUS. NAC. HIST. NAT. PARAG. VOL. 14 (1-2) the metapleuron, in lateral view. Material examined: The specimens used in Pronotal width (PW)- the maximum di- this study were drawn from the following col- ameter of the pronotum, in dorsal lections: view. Hind tibia length (TL)- the length of the ALWC- Alexander L. Wild personal hind tibia. collection, Davis, California, USA. Nodal width (NW)- the maximum width INBP- Museo Nacional del Historial of the petiolar node in dorsal view. Natural del Paraguay, San Nodal length (NL)- the maximum length Lorenzo, Paraguay. of the petiolar node in dorsal view. LACM- Los Angeles County Mu- seum, Los Angeles, California, For species with sufficient available speci- USA. mens, I only measured ants collected in Para- MCZC- Museum of Comparative Zo- guay. However, I was unable to view Para- ology, Cambridge, Massachussetts, guayan representatives of P. commutata and USA. P. crasssinoda, so measurements for those spe- cies were taken from Bolivian and Brazilian Voucher specimens have been deposited at specimens. INBP and LACM. KEY TO THE WORKERS OF PACHYCONDYLA IN CLAVE PARA LAS OBRERAS DE PACHYCONDYLA EN PARAGUAY EL PARAGUAY (note: I have included Pachycondyla (nota: Incluyo en la clave Pachycondyla constricta (Mayr 1884) in this key, indi- constricta (Mayr 1884), marcada con un cated with an asterisk, as its known range asterisco, pues su distribución conocida en in Argentina and Boliva indicates that it is Argentina y Bolivia indica que posiblemente probably found in Paraguay even though it existe en Paraguay, aunque no se ha has not yet been recorded there.) colectado todavia en el país). 1. Dorsal surfaces of mesosoma and metasoma 1. Superficies dorsales de mesosoma y glabrous, nearly entirely devoid of metasoma lisas y brillantes, casi enteramente sculpture; pubescence on metasoma desprovistas de escultura; la pubescencia del extremely sparse to absent; strongly shining mesosoma extremadamente escasa o ausente; black ants.................................................2 hormigas negras fuertemente brillantes.…...2 — Dorsal surfaces of mesosoma and metasoma — Superficies dorsales de mesosoma y not glabrous, covered with moderate to metasoma no lisas y brillantes, cubiertas con dense pubescence, or surface sculpture, or una pubescencia moderada a densa, o con both.......................................................3 escultura, o ambos....................................3 2. Dorsum of head deeply striate; size larger 2. Dorso de la cabeza con estriaciones profundas; (HW > 3.0 mm)........................commutata tamaño mayor (HW > 3.0 mm).......commutata — Dorsum of