Zootaxa 3635 (4): 301–339 ISSN 1175-5326 (print edition) www.mapress.com/zootaxa/ Article ZOOTAXA Copyright © 2013 Magnolia Press ISSN 1175-5334 (online edition) http://dx.doi.org/10.11646/zootaxa.3635.4.1 http://zoobank.org/urn:lsid:zoobank.org:pub:9DB4A023-F9B4-4257-900B-F672F93CD845 A taxonomic revision of the Meranoplus F. Smith of Madagascar (Hymenoptera: Formicidae: Myrmicinae) with keys to species and diagnosis of the males BRENDON E. BOUDINOT & BRIAN L. FISHER 55 Music Concourse Drive, San Francisco, CA 94118, U.S.A. Corresponding author: [email protected] Table of contents ABSTRACT . 301 INTRODUCTION. 302 MATERIALS AND METHODS. 302 Measurements . 304 Indices . 304 Repositories. 306 SYNOPSIS OF MALAGASY SPECIES . 306 DIAGNOSIS OF MALAGASY MERANOPLUS MALES. 306 SPECIES GROUPS. 307 Diagnosis of the M. mayri species group (worker) . 311 Diagnosis of the M. nanus species group (worker). 312 KEY TO SPECIES . 312 Key to workers . 312 Key to queens . 314 Key to males . 316 SPECIES ACCOUNTS . 316 Meranoplus cryptomys new species . 316 Meranoplus mayri Forel, 1910 . 320 Meranoplus radamae Forel, 1891. 327 Meranoplus sylvarius new species . 333 ACKNOWLEDGMENTS . 337 REFERENCES . 338 ABSTRACT The species-level taxonomy of the ant genus Meranoplus F. Smith from Madagascar is revised. Two new species, M. cryptomys sp. n. and sylvarius sp. n. are described from workers and queens; M. mayri Forel, 1910, and M. radamae Forel, 1891, are redescribed, and queens and males for these two species are described for the first time. The first diagnosis of Meranoplus males for any biogeographic region is provided based on Malagasy species. Illustrated keys to all known Malagasy castes and species are presented. Diagnoses are given for two species groups: the M. mayri group and the M. nanus group. The diagnosis of the M. nanus species group from Bolton (1981) is thereby expanded with six new characters. Two species are known from the M. mayri species group and seven described species are known for the M. nanus species group, including the two new species described herein. The mouthparts, genitalia, and all castes, where known, of Malagasy Meranoplus are illustrated. Keywords: genitalia, gynes, Malagasy region, Meranoplini, species groups, wing venation Accepted by J. Longino: 5 Feb 2013; published: 28 Mar. 2013 301 INTRODUCTION Meranoplus is a unique and charismatic myrmicine genus of hairy, slow-moving, and armored ants. The genus is currently classified in its own tribe, the Meranoplini, with one fossil genus, Parameranoplus, from Baltic amber (44.1 ± 1.1 mya; Bolton 2003; Engel 2001; Wheeler 1915). The historic shuffling of Meranoplus through higher taxa—Cryptoceridae, Cataulacinae, Tetramoriini, Meranoplini—reflects our poor understanding of the phylogenetic position of Meranoplus within the Formicidae. Brady et al. (2006) recovered a clade of Meranoplus and Cataulacus, although this relationship was not supported in Moreau et al. (2006). The extant species of Meranoplus are distributed throughout the Old World, absent only from the Palearctic and Oceania regions but with the exception of M. levellei Emery, 1883, from New Caledonia (Fisher 2010; Wheeler 1935). The delineation of the genus Meranoplus is relatively straightforward; the genus is highly derived and unambiguously defined by several synapomorphies. The genus has been revised and reviewed across its entire distribution over the past few decades (Australasian region: Anderson 2006, Schödl 2004, 2007, Taylor 1990, 2006; Ethiopian region: Bolton 1981; and Oriental region: Schödl 1998, 1999). The genus is diagnosed by the compact mesosoma, which is dorsolaterally and often posterodorsally produced, and by the nine-segmented antenna with a three-segmented club (Bolton 2003). With over 80 valid species (Bolton 2012), it is predicted that over half of the Meranoplus diversity remains undescribed, most of these from Australia (Anderson 2006). Species of this genus are predominantly ground-nesting and, when disturbed, will display thanatosis enhanced by crypsis, i.e., individuals will accumulate dirt in their pilosity and play dead (Dornhaus & Powell 2010). With respect to diet, most species are omnivores and facultative granivores, while others, including the whole M. diversus species group, are specialist granivores (Anderson 2000, 2006). At least one species, the Malaysian rainforest-dwelling M. mucronatus F. Smith, 1857, is known to have a trophobiotic relationship with hemipterans (Maschwitz et al. 1987). Meranoplus species are known to be active both day and night (Gross et al. 1991), and to recruit via pheromone trails laid from the base of the sting using secretions from their extremely large Dufour glands (Hölldobler 1988; Billen et al. 2009; Billen & Taylor 1993). The function of the spatulate sting is still unknown (Kugler 1979). The only species of Meranoplus for which mating has been reported is M. peringuiyi Emery, 1886, in which mating swarms occurred after a rain and where males patrolled for the outnumbered females in a zig-zag manner (Robertson & Villet 1989; Schulmeister 2001). Male Meranoplus descriptions are few, varied, and scattered throughout the literature and across the biogeographic regions (Donisthorpe 1949; Forel 1915; Smith 1876). None of these descriptions provide diagnosis of Meranoplus males for any biogeographic region or locale, and most do not provide sufficient detail for genus- level identification. Given the potential of male ants to clarify the natural history of ant reproductive biology (Kaspari et al. 2001), improve the discovery and definition of genera (Yoshimura & Fisher 2009, 2011, 2012a), and aid ant taxonomy and systematics (Brady & Ward 2005; LaPolla 2004; Song & Bucheli 2010; Yoshimura & Fisher 2012b), including descriptions of male ants is a research priority. The biodiversity of Madagascar is exceptionally rich, with levels of endemism ranging from 65% for freshwater fish to 83–86% for non-marine plants, terrestrial vertebrates, and non-marine invertebrates (Goodman & Benstead 2005). Ants exhibit an endemism level of around 95% for the 1,300 Malagasy species, of which about 60% are undescribed (Fisher 2003, 2005; Hita Garcia & Fisher 2012). To this end, twenty-seven modern revisions in print or in press have contributed over 200 new species to the Malagasy ant fauna list. Here we present the first new species of Malagasy Meranoplus in over a century, with keys to all known castes, redescriptions of the workers of M. mayri Forel, 1910 and M. radamae Forel, 1891, the first descriptions of Meranoplus sexuals for Madagascar, and the first diagnosis of the male sex for the genus. MATERIALS AND METHODS Most specimens examined in this study were collected by Fisher et al. over the past two decades, provided with unique specimen identifiers affixed to each pin (viz. CASENT labels), and digitally databased. Every databased specimen record has been uploaded to AntWeb.org, a continuously updated resource that provides “living” distribution maps. Species distributions are illustrated in figs. 64–67. Anatomical terminology predominantly follows prior authorities: mouthparts (Gotwald 1969), wing venation (Yoshimura & Fisher 2012b), setational stature (Wilson 1955), and sculpture (Harris 1979). An exception to 302 · Zootaxa 3635 (4) © 2013 Magnolia Press BOUDINOT & FISHER Yoshimura & Fisher’s (2012b) venation terminology is the use of costal cell on the forewing, rather than costal+subcostal cell; no subcostal cell is present because of the fusion of the subcostal and radial veins in the Aculeata (Gauld & Bolton 1988). To summarize the sculptural terms: areolate is defined as raised ridges which connect to form polygons (cf. promesonotum in fig. 35); costate indicates linear, parallel raised ridges (cf. mesosomal pleurae in fig. 40); dense-punctate describes contiguous punctures (fig. 25); rugose describes non- linear raised ridges (fig. 51). Stellate punctures are defined as punctures having three or more radiating lines (fig. 26). In addition, many Meranoplus species have a carina on the ventral surface of the frontal carina above the scrobe, which is termed the scrobal carina (fig. 2). The term torular lobe is used as defined in Keller (2011), referring to the medial arch of the antennal socket torulus. The term promesonotal shield is unique to Meranoplus, and refers to the fused pro- and meso- segments of the mesosoma, which are often elongated as shelves laterally and posteriorly (Bolton 1981). Although abdominal segments IV–VII are distinctly constricted anteriorly in Meranoplus, we eschew the term gaster as it refers to different tagmata across the ant subfamilies (Keller 2011). For genitalia, we follow the terminology of Boudinot (2013) which reflects the homologies of male ant genitalia with basal Hymenoptera; terms utilized by Yoshimura & Fisher (2011) are indicated in parentheses. The genitalia are composed of the cupula (= basal ring) and three paired valves: the parameres, volsellae, and penisvalvae (= aedeagal plates). The lateral-most valve, the paramere, is composed of the basal basimere and distal telomere (= harpago). The volsella, medial to the paramere and lateral to the penisvalva in situ, and is composed of the basivolsella, cuspis, and digitus. The cuspis and digitus are the distal elements of the volsella, and can be recognized by their position and shape: the cuspis is lateral (closest to the paramere), lobe-like, and extends anteriorly (basally) as a setose plate, while the digitus is medial (near the penisvalva) and