First record of the myrmicine ant genus Carebara Westwood, 1840 (Hymenoptera, Formicidae) from Saudi Arabia with description of a new species, C. abuhurayri sp. n.

Abstract The myrmicine ant genus Carebara is recorded for the first time in Saudi Arabia from the Arabian Peninsula as a whole. A new species Carebara abuhurayri sp. n. is described based on workers collected from Al Bahah region. One of the smallest ant species known to occur in Arabia, Carebara abuhurayri is found in an area inhabited by many ant species including Tetramorium sericeiventre Emery, 1877, Pheidole minuscula Bernard, 1952, Pheidole sp., Monomorium destructor (Jerdon, 1851), Monomorium exiguum (Forel, 1894) and Monomorium sp. and Crematogaster sp.


Introduction
Th e ant genus Carebara Westwood, 1840, sensu Fernández (2004, is one of the largest ant genera of subfamily Myrmicinae with more than 180 species (Bolton et al. 2006) distributed worldwide in the tropics (Brown 2000) and the Afrotropical region (Weber 1950). Many of them are very tiny cryptic soil and leaf litter inhabitants (Longino 2004). Th ey nest in rotten wood to which the bark is still adherent in the Afrotropical region (Bolton 1973), or may be lestobiotic (Longino 2004) nesting near other ant species. Little is known about the biology of the species.
Th e genus Carebara sensu Fernández (2004) was unknown from Arabia prior to the description of C. arabica (= Oligomyrmex arabicus) from Yemen by Collingwood and Van Harten 2001). Although the description of C. arabica might have been more explicit, it was based on major and minor workers, with drawings of both. Here, we give the fi rst record of a Carebara species from Saudi Arabia based on the new species, C. abuhurayri.

Measurements and indices
Measurements in mm and indices are as follows (Bolton 1987 Overall unicolorous yellow, smooth and shining (Fig.1). Head (Fig.2) distinctly longer than broad, with clearly convex sides and a straight posterior margin. Mandibles smooth and shining with relatively long yellow hairs and armed with four teeth. Median portion of clypeus fl at. In anterolateral view, clypeal lateral carinae strongly narrowed posteriorly between frontal lobes, then continued as a frontal triangle. Eyes minute and with a single ommatidium (Fig.3). Scapes fail to reach head posterior margin by about one-third the head length. Th e scapes broaden evenly from about mid-length. Mesosoma in profi le slightly convex. Metanotal groove shallow but distinct, dorsally and laterally (Fig.4). Propodeum obliquely angled (Fig.5). Propodeal spiracle (Fig.5, 6) relatively large, circular, high and close to propodeal declivity. Metapleural gland orifi ce prominent. Petiole longer than broad in dorsal view with short peduncle. Postpetiole node lower than petiole and dorsally distinctly convex, nearly as long as broad in dorsal view (Fig.7). Pilosity appressed, few and short on mesosoma, petiole, postpetiole, and rare on fi rst gastral tergite, underside of head with a few short straight hairs. Th e clypeus has two pairs of standing hairs, the central pair long, and the lateral pair shorter. Anterior sides of head very fi nely longitudinally striated (Fig.8). Dorsum of head with abundant scattered hair pits. Lower half of mesopleura, metapleura, and petiole and postpetiole with areolate-rugose sculpture (Fig.5).
Paratypes  Given the anomalies of the Fernández (2004) schema and with only minute monomorphic workers, we are unable to place this new species within his speciescomplexes (denominated as species-groups in Fernández 2010). In the old schema, workers with 10-segmented antennae would fall in the Genus Oligomyrmex Mayr subgenus Aeromyrma Forel. Th ose, however, like all the Oligomyrmex, have dimorphic workers but, from the present collection, C. abuhurayri has only a small worker morph. Carebara arabica has major and minor workers, both appearing to have 11-segmented antennae. Th e minor is larger, TL 1.3 mm, than C. abuhurayri, TL max 1.13 mm, and the propodeum profi le of the minor has a sharp angular transition from the dorsum to the declivity.
Etymology. Th is new species is named after Abuhurayra, the companion of the Prophet, Mohammed, may peace and blessing be upon him, and whose tribe inhabited Al Bahah region.
Biology. Th e specimens of C. abuhurayri were found foraging on the ground and coexisting with the ant species Tetramorium sericeiventre Emery, 1877, Pheidole minuscula Bernard, 1851, Pheidole sp., Monomorium destructor (Jerdon, 1851), Monomorium exiguum (Forel, 1894), Monomorium sp. and Crematogaster sp. Th is association with the above taxa may indicate a "lestobiotic" relationship (Longino, 2004) but at present, it is not known with which of these above species C. abuhurayri is nesting. It is worth mentioning that C. abuhurayri is one of the smallest ant species known to occur in Arabia.
Th e type locality is a mountainous area which is considered as a part of upper Tihama territory which belongs to Al Bahah region (Fig. 13). Th e locality has a great diversity of wild plants and many cultivated fruits, especially banana, date palm, and Ficus trees, also alfalfa, and some lemon trees are cultivated. Many water streams are present in the area, therefore, the soil has a considerable degree of humidity all year round. Such habitats are found elsewhere in Arabia and so this or related species can be expected in most Arabian countries. For Saudi Arabia, we are expecting to record them in the Asir mountain chain, especially in the lower elevation areas which are called Tihama. We hope future collecting will allow clarifi cation as to whether C. abuhurayri has monomorphic or dimorphic workers and the nature of the queen.

Additional Arabian species
Carebara arabica (Collingwood & van Harten, 2001) which was described as Oligomyrmex arabicus from Yemen based on major and minor workers, and is known only from a single collection, is an example of a long-headed species with 11-segmented antennae (in the original description, the SL for major is given wrongly as 0.63, from the illustration it would be ca 0.16). Th e small worker of the new species C. abuhurayri appears not too dissimilar to the minor worker of C. arabica but it is consistently smaller in size (TL 0.99-1.13 mm versus TL 1.30); has a higher cephalic index (CI 74-89 versus CI 71), and a relatively lower head length (HL 0.35-0.41 versus HL 0.42). In addition, C. abuhurayri has a distinct but shallow metanotal groove compared with the deep groove in C. arabica. It does not resemble Carebara afghanus Pisarski, 1990, which has 9-segmented antennae but has a low, elongated and fl at alitrunk profi le without propodeal spines. Th e presence of single facet eyes, however, is the main characteristic, that sets C. abuhurayri apart from some of the African Carebara.
In pre-Fernández taxonomy C. abuhurayri might fall in the Oligomyrmex subgenus Aeromyrma, i.e. those with 10-segmented antennae. Th e only sub-Saharan species with 4-toothed mandibles is O. jeanneli Santschi, 1913. Th is has minor, TL 0.9 mm; metanotal groove shallow, dorsum of propodeum short; petiole noticeably narrower than postpetiole, postpetiole wider than long; head smooth, feebly punctuate, shiny; eyes atrophied set at anterior third of side; scape reaches posterior third of the head; petiole wider than high; postpetiole transverse, twice as wide as long; promesonotum wider than long; dorsum of propodeum wider than long unarmed; yellow, smooth and shiny.