Monomorium mohammedi

Collected from leaf litter under a Hyphaene tree (Arecaceae) and a nest in a thin layer of clay soil above sandy soil under a Mango tree. Only known from the type locality.

Identification
Sharaf and Hita Garcia (2018) - Monomorium mohammedi can be readily diagnosed by the combination of the following characters: eyes distinctly small, with 5–6 ommatidia; mesosoma, petiole, and postpetiole without standing hairs; mesopleuron, metapleuron, petiole and postpetiole finely shagreened.

This species is closest to Monomorium guillarmodi from Lesotho in terms of the small body size, tiny eyes, 11-segmented antennae, lack of hairs on mesosoma, and the smooth body. However, M. mohammedi is readily separated from M. guillarmodi by the following characters: the posterior margin of head without hairs and concave in full-face view, petiole and postpetiole without hairs, median clypeal portion without anterolateral angles or carina, scape relatively longer (SI 81–97), whereas M. guillarmodi has a transverse posterior head margin with 1–2 pairs of hairs, petiole and postpetiole each with a single pair of hairs, median clypeal portion prominent with well-defined anterolateral angles and distinct carina, and scape shorter (SI less than 80).

Among the Arabian species of the M. monomorium-group four species have 11-segmented antennae: Monomorium mohammedi, Monomorium clavicorne, Monomorium aeyade, and Monomorium exiguum. Monomorium mohammedi is easily separated from clavicorne by its smaller eyes, smaller terminal funicular segment, and lack of mesosomal pilosity, whereas clavicorne has larger eyes, greatly swollen terminal funicular segments, and abundant hairs on the mesosoma. When comparing M. mohammedi with M. aeyade, both lack hairs on the mesosoma but M. mohammedi can be immediately separated by its smaller eyes with only 5 ommatidia that are situated distinctly farther apart from the mandibular insertions (EM 0.09–0.11), the finely shagreened meso- and metapleuron, the hairless petiole and postpetiole, whereas M. aeyade has larger eyes (EL 0.24 × HW), with a ring of ommatidia encircling a single row of 2 ommatidia that are situated closer to the mandibular insertions (EM 0.05); meso-and metapleuron smooth, and petiole and postpetiole each with one pair of hairs.

Distribution based on Regional Taxon Lists
Afrotropical Region: Saudi Arabia.

Nomenclature

 * . Monomorium mohammedi Sharaf & Hita Garcia, in Sharaf, Al Dhafer, et al. 2018: 20, fig. 9 (w.) SAUDI ARABIA.
 * Type-material: holotype worker, 6 paratype workers.
 * Type-locality: holotype Saudi Arabia: Almajardah, Wadi Khat, 19.08913°N, 41.97126°E, 513 m., 10.xi.2012 (M.R. Sharaf); paratypes: 2 workers with same data, 3 workers Saudi Arabia: Jazan, Wadi Shahdan, 17.45222°N, 42.71516°E, 200 m., 13.xi.2012 (M.R. Sharaf), 1 worker Jazan, Abu Arish, 17.01347°N, 42.80160°E, 90 m., 10.iv.2012 (M.R. Sharaf).
 * Type-depositories: KSMA (holotype); CASC, KSMA, WMLC (paratypes).
 * Distribution: Saudi Arabia.

Worker
Holotype: TL 1.37; HL 0.41; HW 0.31; SL 0.25; EL 0.04; EM 0.09; ML 0.42; PW 0.19; PTL 0.15; PTW 0.08; PTH 0.11; PPL 0.07; PPW 0.08; PPH 0.08; CI 76; EI 13; SI 81. Paratypes (n=7): TL 1.32–1.53; HL 0.38–0.44; HW 0.29–0.32; SL 0.26–0.29; EL 0.04– 0.05; EM 0.09–0.11; ML 0.36–0.44; PW 0.18–0.21; PTL 0.08–0.11; PTW 0.07–0.08; PTH 0.09–0.12; PPL 0.05–0.07; PPW 0.08; PPH 0.08; CI 71–82; EI 13–17; SI 88–97.

Head. In full-face view distinctly longer than broad with shallowly convex or nearly parallel sides and clearly concave posterior margin in full-face view; median clypeal portion without carina or anterolateral angles, anterior clypeal margin feebly concave; antenna 11-segmented; scapes short, when laid straight back, just surpassing midlength of head (SI 88–97); mandibles armed with three teeth, decreasing in size from apex to base; eyes oval, tiny, (EL 0.13–0.15 × HW) with 5 ommatidia, set in front of midlength of head; frontal lobes farther apart in full-face view; underside of head with six scattered short hairs. Mesosoma. In profile with a flat promesonotal dorsum, which slopes posteriorly to a well-defined metanotal groove; propodeal spiracles small and pinhole-like; propodeal dorsum evenly sloping posteriorly to short declivity. Petiole. Node massive, narrowly rounded above, and little higher than postpetiolar node in profile; anterior peduncle short; ventral petiolar surface below node broadly convex extending anteriorly to form a blunt broad dent. Postpetiole. Node small with convex dorsal margin; postpetiole as high as broad. Sculpture. Cephalic surface smooth and shining; mandibles smooth and shining, with faint striations on the outer margin; mesosoma dorsum and propleuron smooth and shining; meso-and metapleuron finely shagreened; metanotal cross ribs distinct; petiole and postpetiole with traces of superficially shagreened sculpture, but never smooth; gaster smooth and shining. Pilosity. Underside of head without hairs; cephalic surface with scattered minute hair-pits; anterior clypeal margin and mandibles with longer hairs; antennae with abundant appressed hairs; mesosoma without hairs, only rare appressed pubescence; petiole and postpetiole without hairs, only few appressed pubescence dorsally; gaster with scattered appressed pubescence, few longer hairs on the last gastral tergites.

Color. Overall uniform clear yellow, mandibular teeth light brown.

Type Material
Holotype, pinned worker, KSA: Almajardah, Wadi Khat, 19.08913◦N, 41.97126◦E, 513 m, 10.xi.2012, (Sharaf MR) (: CASENT0823774). Paratypes, six pinned workers: KSA: 2 w, with same data as the holotype (KSMA); 3 w, Jazan, Wadi Shahdan, 17.45222◦N, 42.71516◦E, 200 m, 13.xi.2012, (Sharaf MR) (1 in : CASENT0922351, 2 in KSMA); 1 w, Jazan, Abu Arish, 17.01347◦N, 42.80160◦E, 90 m, 10.iv.2012, (Sharaf MR).

Etymology
The name of the new species is a patronym in honor of Mohammed Sharaf, the eight year old son of the senior author.

References based on Global Ant Biodiversity Informatics

 * Sharaf M., H. M. Al Dhafer, A. S. Aldawood, and F. Hita Garcia. 2018. Ants of the Monomorium monomorium species-group (Hymenoptera: Formicidae) in the Arabian Peninsula with description of a new species from southwestern Saudi Arabia. PeerJ 6:e4277; DOI 10.7717/peerj.4277