First Record of the Myrmicine Ant Genus Meranoplus Smith, 1853 (Hymenoptera: Formicidae) from the Arabian Peninsula with Description of a New Species and Notes on the Zoogeography of Southwestern Kingdom Saudi Arabia

The ant genus Meranoplus is reported for the first time from the Arabian Peninsula (Kingdom of Saudi Arabia) by the new species M. pulcher sp. n., based on the worker caste. Specimens were collected from Al Sarawat and Asir Mountains of southwestern Kingdom of Saudi Arabia using pitfall traps. Meranoplus pulcher sp. n. is included in the Afrotropical M. magretii-group, with greatest similarity to M. magrettii André from Sudan. A key to the Afrotropical species of the M. magretii-group is presented. A brief review of the ant taxa with Afrotropical affinities in southwestern region of the Kingdom of Saudi Arabia is given.


Introduction
Since Smith [1] established the genus Meranoplus, 87 species and subspecies are currently included [2]. This genus is broadly distributed in the Old World tropics, ranging through the Afrotropical, Malagasy, Oriental, and Indo-Australian regions [3][4][5]. The genus is absent from the Palaearctic and Oceania regions, except for a single species, M. levellei Emery, 1883 from New Caledonia [6,7].
Available information on the habitats and biology of Meranoplus species is limited. Most species nest directly in the soil, under stones, in rotten wood or in leaf litter [3,4,13]. African species have been reported to nest either in the ground with a crater type of entrance, or at the base of plants. Nests of one or two species are constructed among roots with workers ascending trees or low shrubs [3]. The majority of species are generalized omnivores [13], whereas others are considered seed harvesters, e. g. M. diversus-group [4,13,18].
The specialized morphology of the genus Meranoplus is related to a specialized behaviors, thanatosis, ''playing dead'' and and becoming cryptic. Several species when disturbed, fold their legs beneath the promesonotal shield and quickly accumulate dirt on body hairs and remain motionless in a fetal-like position [19,20].
A thorough diagnosis of the genus Meranoplus has been provided by Bolton [3,21]. The genus can be recognized by the combination of the following traits, masticatory margin of mandibles armed with four to five teeth; palp formula 5, 3; clypeus large, with median portion usually carinate at each side; antennal scrobes well-developed, usually long; antennae ninesegmented with a three segmented club; eyes large, located behind midlength of head, sometimes close to the posterior corners of head; pronotum and mesonotum fused into a plate or shield that extends posteriorly and laterally so the mesosomal sides, and usually also the propodeum, are concealed in dorsal view; lateral and/or posterior margins of promesonotal shield usually armed with spines, lobes, foliacious processes; petiole sessile usually cuneate in lateral view.
The M. magrettii-group can be distinguished by the following characters [3]: masticatory margin of mandibles armed with four or five teeth; mesosoma when seen from above with the propodeum concealed by the broad promesonotal shield; propodeal spines present; petiole cuneate in lateral view with unarmed dorsal surface; postpetiole broad and nodiform.
The M. magrettii-group has only two species known from the Afrotropical region, M. magrettii a species that is broadly distributed in the region and inhabiting savannah, grassland and dry woodland, and M. peringueyi apparently confined to South Africa [3].
The southwestern mountainous region of the Kingdom of Saudi Arabia (KSA) is one of the most diverse in terms of species diversity and relative abundances of insects. Taxonomic and biogeographical studies have indicated that the insects of this region have strong affinities with the Afrotropical Region [21][22][23][24][25][26][27][28][29][30][31][32][33]. A recent and comprehensive study of the Afrotropical relationships of the region is by El-Hawagryi et al. [32]. These authors recorded 17 orders of insects representing 129 families and at least 582 species and subspecies from Al-Baha Province. Their biogeographic analysis of the species composition clearly revealed that this region has a close affinity with the insect fauna of the Afrotropical Region.
In the present study, the myrmicine ant genus Meranoplus is recorded for the first time from KSA by the new species M. pulcher sp. n. and represents a new generic record for the Arabian Peninsula. In addition, a synopsis of the similarity of the Afrotropical fauna with the southwestern region of KSA is presented based on available records of ants.

Sampling procedures
Materials listed in this work, the holotype and 29 paratype specimens were collected during an insect inventory of the southwestern region of KSA by using more than 900 pitfall traps. A single specimen of the new species was collected by an aspirator from a Cactus sp. All the materials is deposited in King Saud University Museum of Arthropods, College of Food and Agriculture Sciences (KSMA), King Saud University, Riyadh, Kingdom of Saudi Arabia, except a single paratype specimen in California Academy of Sciences (CASC), San Francisco, USA.
All measurements and indices are expressed in millimeters and follow the standards of Boudinot & Fisher [5].    Illustrations Specimens were photographed by Michele Esposito (CASC) using a JVC KYF70B3CCD digital camera attached to a Leica M420 stereomicroscope. All digital images were processed using Auto-Montage (Syncroscopy, Division of Synoptics Ltd, USA) software. Images of the specimens are available in full color on www.antweb.org. The map was created by the ArcGIS 9.2 program, with the help of Prof. Mahmoud S. Abdel-Dayem (King Saud University).Specimens were examined and imaged using scanning electron microscope (SEM) (JSM-6380 LA) visualization to record morphological details of the new species. The JSM-6380 LA is a high-performance scanning electron microscope with a high resolution of 3.0 nm.
No specific permits were required for the described field studies or for the surveyed locations which are not privately-owned or protected in any way or do not have endangered or protected species.

Nomenclatural acts
The electronic edition of this article conforms to the requirements of the amended International Code of Zoological Nomenclature, and hence the new names contained herein are available under that Code from the electronic edition of this article. This published work and the nomenclatural acts it contains have been registered in ZooBank, the online registration system for the ICZN. The ZooBank LSIDs (Life Science Identifiers) can be resolved and the associated information viewed through any standard web browser by appending the LSID to the prefix "http://zoobank.org/". The LSID for this publication is: urn: lsid:zoobank.org:pub:80A78374-53CF-4A19-90CB-4A392E62699 9. The electronic edition of this work was published in a journal with an ISSN, and has been archived and is available from the following digital repositories: PubMed Central, LOCKSS.

Paratypes workers
All the following paratype specimens are deposited in KSMA, 3 workers, same locality and data as the holotype; 1 worker with  Mesosoma. Anterior pronotal corners armed with a pair of short triangular teeth; promesonotal shield distinctly broader than long (PMI 144-155) widening behind pronotum; promesonotal suture absent; posterior corners of mesonotum armed with a pair of sharp spines; posterior mesonotal margin between spines strongly concave and without secondary armament; propodeal spines long and sharp originating at level of propodael spiracles and curved upwards; propodeal lobes well-developed.
Pilosity. All body surface covered with fine, pale, profuse hairs.
Colour. Colour unicolorous yellow, in some specimens, postpetiole and posterior margin of first gastral tergite brownish. The six examined specimens showed a clear size variation.

Etymology
The species name is derived from the Greek word ''pulcher'' that means ''beautiful'' referring to the attractive appearance of this ant species.

Habitat
Twenty five workers of the new species were collected from Al-Baha Province, Shada Al Ala Protectorate (Fig. 14) and six workers from Raydah Protectorate. Both collections were from pitfall traps placed next to Acacia trees. The soil was extremely dry with abundant dry seeds of shrubs. Despite several hours of  observing the nest no additional specimens were found. Pitfall trapping is apparently an efficient method for collecting this group of ants.

Key to the Afrotropical species of Meranoplus magrettii-group based on workers
In the key to Afrotropical species (Bolton [3]:48), Meranoplus pulcher sp. n. will key to couplet 7 along with peringueyi and magrettii. Couplet 7 is modified here to separate the three species of the M. magrettii-group.

Zoogeography of the southwestern region of Kingdom of Saudi Arabia
The KSA is located at the interchange of three major biogeographical realms, the Palaearctic, Afrotropical and Oriental. Much mixing of these faunal elements has occurred. Geologically, the Ethiopian and Arabian Peninsula highlands and mountains separated approximately 13 mybp producing the Great Rift Valley through a rifting process as the African continental crust separated [34,35]. Biogeographically, the southwestern region of the KSA belongs to the Afrotropical region [21][22][23][25][26][27][28][29][30][31][32][33].
Studies of other taxonomic groups of insects have revealed similar results, for example, the Scythrididae (flower moths) (Lepidoptera: Gelechioidea) were treated for the Palaearctic region [36] [38]. The sole faunistic work carried out for the knowledge of the ants of KSA [38] recorded 89 species from southwestern region, 18 of which having an Afrotropical distribution (table 1). Despite limited amount of specimens collected from this region mentioned in the above work, preliminary conclusions supported an Afrotropical faunal relationship of the region. Recently, six new species were described from the region [28][29][30][31][32][33], taxa more closely related to Afrotropical congeners ( Table 2). An approximate estimate of the relative percentage of the Afrotropical faunal similarity of the region is 31%. Taking into account the unidentified materials accumulated over the last ten years from the region by the authors and also the vast area of the region, some of which has not been surveyed, it is expected this number will increase.

Discussion
Meranoplus pulcher sp. n. is the first member of the genus recorded from KSA and from the vast Arabian Peninsula. Following Bolton [3], it belongs to M. magrettii-group and cannot be identified using the available keys to species of Afrotropical [3], Malagasy [5], Oriental [11] or Australian [13,17] regions. Meranoplus pulcher sp. n. is similar to M. magrettii André from Sudan to which it will key to in Bolton [3], sharing the following characters: mandibles striate and armed with four teeth, anterior pronotal corners armed with a pair of short triangular teeth, promesonotal shield narrowing behind pronotum, posterior corners of mesonotum armed with a pair of short spines, posterior mesonotal margin concave and unarmed, petiole cuneate in profile and postpetiole nodiform.
The habitats of M. pulcher sp. n. and M. magrettii apparently are not similar. The latter species is restricted to sub-Saharan Africa and has been collected from savannah, open-woodland and grassland habitats [3]. Meranoplus pulcher sp. n.is apparently restricted to juniper woodlands of southwestern mountains of KSA. The author (MRS) has made extensive collections of ants from the southwestern KSA. Typical Afrotropical ant genera mentioned above (e.g. Strumigenys, Anochetus, Pachycondyla, Cerapachys, Dorylus etc.) were commonly encountered. For example, the Afrotropical species, S. arnoldi Forel was reported from Al-Baha Province [39] providing evidence of faunal similarities with the Afrotropical Region. Additional future collections from this area of KSA will no doubt provide further evidence of this biographical connection.