Two new ant species (Formicidae: Dorylinae, Ponerinae) from New Caledonia

. Two new species of ants (Hymenoptera: Formicidae) collected from New Caledonia are described and figured based on worker specimens: Leptogenys loarelae Ramage sp. nov. (Ponerinae, Ponerini) and Lioponera neocaledonica Jouault, Ramage & Perrichot sp. nov. (Dorylinae, Cerapachyini). All specimens were collected from the South Province of Grande Terre. These two new species are primarily distinguished from the other New Caledonian relatives by the size and shape of petiole for L. loarelae Ramage sp. nov. and by the presence of dorsolateral margins on the mesosoma for L. neocaledonica Jouault, Ramage & Perrichot sp. nov. Keys to New Caledonian Leptogenys and Lioponera are provided. and posterior margins of abdominal segments IV to V brown. Body finely and sparsely punctate; reticulation present on sides of the mesosoma, becoming shallower from propleura to propodeum; cinctus, abdominal segment IV, base of abdominal segments V, VI and pygidium transversally, finely and shallowly striate. Body covered with suberect hairs; scape with abundant appressed hairs; tibiae with scattered decumbent hairs; tarsi with abundant decumbent to appressed hairs; declivous face of propodeum with short, dense and appressed hairs.

Grande Terre, which is divided in length by a central mountain range, as well as the Belep Islands to the North, the Loyalty Islands to the East, the Isle of Pines to the South, the Chesterfield Islands and Bellona Reefs to the West, and few islets, all with a tropical marine climate. New Caledonia is considered a part of Zealandia, a continental fragment originating from the former Gondwana, with addition of terranes that accreted after the break up of Gondwana about 84 million years ago (Ma). The current New Caledonian biota displays a high diversity and endemism resulting from a complex geological and biogeographical history, with Palaeocene and Eocene submersions followed by colonization and radiations of taxa of both Gondwanan and Indo-Malayan origins in the last 37 Ma (Grandcolas et al. 2008;Nattier et al. 2017). However, there is still a debate on whether the archipelago was entirely or partially submerged, with the survival of archaic groups on ephemeral islands (Heads 2019). Emery's (1883) pioneer work on the ant fauna of New Caledonia resulted in the description of seven species. He was soon followed by André (1889) and Forel (1894) who added two and three species, respectively, and he himself described 37 additional species, most of them endemic to the archipelago (Emery 1914). Since then, most of the species described from New Caledonia were part of regional or global generic revisions (Viehmeyer 1924;Brown 1958;Wilson 1958;Brown & Kempf 1960;Bolton 2000;Baroni Urbani & de Andrade 2003;Lucky & Ward 2010;Heterick & Shattuck 2011;Shattuck 2011;Taylor 2018;Sparks et al. 2019), with, however, some works focusing on New Caledonia (Brown 1948;Wilson 1957;Ward 1984). Wheeler (1935), Taylor (1987) and Jennings et al. (2013) also produced local ant checklists. To date, the New Caledonian ant fauna comprises 134 species and subspecies, 55% of which apparently endemic (Antweb 2019). However, recent studies (Berman 2012;Berman & Andersen 2012;Berman et al. 2013aBerman et al. , 2013bAntwiki 2019) show many species remaining to be described.
Here, we report new species of Leptogenys Roger, 1861 and Lioponera Mayr, 1879, two genera of epigaeic predatory ants collected from mountain forests of Grande Terre. We also provide identification keys for the New Caledonian species to facilitate future work on these two genera.
The genus Leptogenys is found throughout the world's tropical and subtropical zones with over 300 known extant species (Bolton 2019). Molecular phylogenetic analyses showed that Leptogenys is a monophyletic taxon within the Odontomachus genus group (Schmidt 2013). The diversification of this group probably occurred in Africa between 40 and 30 Ma and had an explosive nature (Schmidt 2013). Leptogenys is the most species-rich genus within the subfamily Ponerinae and its members display a diversity of foraging strategies and reproductive systems (Schmidt & Shattuck 2014). Important taxonomic work has been done on this genus: Lattke (2011) revised the New World fauna, Rakotonirina & Fisher (2014) the Malagasy fauna, Xu et al. (2015) the Oriental species and Arimoto (2017) the modiglianii species group. Keys for the Indian fauna are found in Bharti & Wachkoo (2013) and for Leptogenys of the Arabian Peninsula in Sharaf et al. (2017). Most species of Leptogenys are known as specialized predators of isopods (Dejean & Evraerts 1997;Dejean 1997). The presence of ergatoid gynes and gamergates has been established in most of the studied species, but flying queens were also found in two Asian species (Peeters 2012). Ergatoid queens and gamergates is an alternative to breedings with winged breeders. Indeed, it guarantees a strategy of rapid and less expensive reproduction by the fission of colonies. However, it is obvious that dispersal capabilities, particularly at long distances, are lost in the fission of colonies (Schmidt 2013). Reproductive methods of this type remain unclear since winged gynes have been reported for two Asian species (Ito & Okawahara 2000).
The genus Lioponera was synonymized with Cerapachys Smith, 1857 by Brown (1975), but revived from synonymy by Borowiec (2016). Lioponera is found in Africa, Asia and Oceania, mainly in tropical and subtropical zones, and is currently known to comprise 74 species (Antweb 2019). Australia hosts a major radiation of Lioponera, with 43 reported species. Lioponera is sister to the clade comprising Lividopone Bolton & Fisher, 2016, Parasyscia Emery, 1882and Zasphinctus Wheeler, 1918(Brady et al. 2014. Phylogenetic studies suggest that the genus may have originated in Africa and later spread to the Indomalayan and Australasian regions (Borowiec 2019). Lioponera occurs only in the Old World and all species observed thus far prey on other ants.

Taxon sampling
The material examined in this study is based on sampling carried out in the South Province of Grande Terre. One specimen was collected in 2010 by Maïa Berman during her PhD on ant ecology (Fire project) at Charles Darwin University (Australia) (Berman 2012). All other specimens were collected by VP in 2011, during experimental fieldwork for actuo-paleontological studies of resin-producing araucarian forests of New Caledonia (e.g., Beimforde et al. 2017). Both samplings were conducted with permission obtained from the Direction de l'Environnement de la Province Sud (permit 1357-2010/ARR/DENV to Alan Andersen/Maïa Berman and 17778/DENV/SCB to VP).

Repositories
Collections are referred to by the following acronyms: ANIC = Australian National Insect Collection, Canberra CASENT = California Academy of Sciences, Entomology, San Francisco, USA MNHN = Muséum national d'histoire naturelle, Paris, France

Specimen examination
The taxonomic analysis was conducted using an AMSCOPE stereo microscope equipped with a micrometer, at magnification 40 ×. Series of photographs were taken at different focal planes using a Canon EOS 60D camera mounted on a Nikon SMZ 1500, stacked using CombineZP or Helicon Focus and processed with Adobe Photoshop.

Diagnosis
Leptogenys loarelae Ramage sp. nov. can be distinguished from other New Caledonia species of Leptogenys by the unique combination of the following features: integument smooth and shining, mostly black colored with blueish reflection; third antennal segment markedly elongate, more than twice the length of pedicel; mandible elongate, triangular; petiole elongate, nearly three times longer than broad in dorsal view.

Etymology
The specific epithet refers to the first name of Thibault Ramage's daughter, Loarel. The species epithet is to be treated as a noun in the genitive case. Head. Elongate, sub-trapezoidal, lateral sides diverging anteriorly (Fig. 1B); lateral margin barely convex; posterior margin weakly concave medially, posterior lateral corners rounded. Clypeus triangular, with blunt apex and sligthly concave side margins. In full-face view, eye large, oval, maximum diameter greater than twice the maximum width of scape; placed at head midline. Antennae with scape long and slightly enlarged medially, surpassing posterior margin of head by its 2⁄₅ th ; funicular segments elongate; third antennal segment markedly elongate, more than twice the length of the second. Mandible triangular, elongate, shorter than head width; masticatory margin edentate. MesosoMa (Fig. 1A, C). Elongate, compressed laterally, widest at pronotum; mesosomal dorsal surface in profile slightly convex. In dorsal view, mesonotum as long as broad. Propodeal spiracle slit-like. Petiole (Fig. 1A, C-D) elongate, nearly three times as long as broad, trapezoidal, widest at apex; dorsal surface of petiolar node convex, posterior surface slightly concave, anterodorsal and posterodorsal corners angular. Subpetiolar process small, trapezoidal; located beneath anterior 1⁄₅ th of the petiole (Fig. 1D). Gaster elongate.

Etymology
The specific epithet refers to New Caledonia where the species was discovered.  Emery, 1914 (CASENT0270535). B. L. sagaris Wilson, 1958 (CASENT0270576). Images: A by Estella Ortega, B by Ryan Perry. Head (Fig. 4C). Sub-rectangular, slightly longer than broad, widest above midline of head; lateral sides slightly convex; vertexal margin slightly concave, posterior lateral corners slightly rounded. Parafrontal ridges angular. Compound eyes of medium size, situated below midline of head. Mandible elongate, triangular, masticatory margin with 10 small teeth. Antennae with scape short and clavate, reaching up to two fifth of posterior margin of head.
InteguMent. Mostly black except last two funicular articles, tarsomeres, and posterior margins of abdominal segments IV to V brown. Body finely and sparsely punctate; reticulation present on sides of the mesosoma, becoming shallower from propleura to propodeum; cinctus, abdominal segment IV, base of abdominal segments V, VI and pygidium transversally, finely and shallowly striate. Body covered with suberect hairs; scape with abundant appressed hairs; tibiae with scattered decumbent hairs; tarsi with abundant decumbent to appressed hairs; declivous face of propodeum with short, dense and appressed hairs.

Discussion
The new species described above were mostly collected along the trail from Sarraméa to the Plateau de Dogny, except the specimen collected from the Montagne des Sources. Both localities are situated in the central mountain range of New Caledonia and display humid forests growing on an ultramafic ground. The trail to Plateau de Dogny shows three different plant zonations along a gradient of elevation from 20 to 1030 m. There, Lioponera was collected on the forest soil at an elevation of 441 m, which corresponds to a mixed humid forest supporting abundant shrubs of the remarkable, endemic basal angiosperm species Amborella trichopoda Baill. (Amborellaceae) as well as ferns of the Marattiaceae, namely Ptisana rolandiprincipis (Rosenst.) Christenh. (Fig. 6). Leptogenys was collected on the soil at an elevation of 897 m, which corresponds to a humid forest harbouring plenty of trees of the likewise endemic Austrotaxus spicata Compton (Taxaceae).
Specialized predation on oniscoid isopods seems to dominate in the genus Leptogenys, although there have been reports on other preys such as earwigs or termites (Bolton 1975;Steghaus-Kovac & Maschwitz 1993;Dejean 1997;Dejean & Evraerts 1997). Some Oriental species have an army ant lifestyle and are generalists (Witte & Maschwitz 2000). Unfortunately, no data exist on the diet of the New Caledonian  Leptogenys. Leptogenys loarelae Ramage sp. nov., together with L. acutangula and L. sagaris from New Caledonia, shares affinities with the Leptogenys fauna of Australia and Papua New Guinea. Leptogenys keysseri Viehmeyer, 1914, from Papua New Guinea, is largely similar to L. loarelae Ramage sp. nov., but its petiole is much more narrowed anteriorly.
Species of Lioponera are predators of other ants, like most other Dorylinae (Borowiec 2016). At least one species in Australia exhibits a preference in preying on Pheidole Westwood, 1839 (Hölldobler 1982), and in Japan one species seems to prey on Monomorium Mayr, 1855 (Idogawa & Dobata 2018). In New Caledonia, Wilson (1957) observed Lioponera cohici raiding colonies of a species of Pheidole, while he found remains of an undetermined species of Lordomyrma Emery, 1897 in a nest of Lioponera dumbletoni. Data on the diet of Lioponera neocaledonica Jouault, Ramage & Perrichot sp. nov. are missing.
Based on these two new discoveries, it is certain that important inventorial and taxonomic work remains to be done in New Caledonia. This first publication will serve as a basis for future work on the myrmecofauna of New Caledonia.