Leptogenys polaszeki Sharaf & Akbar

Mostafa R. Sharaf, Shahid A. Akbar, Hathal M. Al Dhafer & Abdulrahman S. Aldawood, 2017, A new ant species of the Leptogenys sulcinodagroup (Hymenoptera: Formicidae) from Saudi Arabia, Zoology in the Middle East 63 (1), pp. 68-75 : 69-74

Leptogenys polaszeki Sharaf & Akbar sp. n.

Worker ( Figures 1 , 6A, C, E)

Material. Holotype: Asir Province: Abha, Raydah, Saudi Arabia, 18.19465°N, 42.39485°E, alt. 1851 m, 06.ix.2015 (Al Dhafer leg.), Pitfall Trap ( P.T.), No. 1-3-1 , King Saud University Museum of Arthropods ( KSMA), Riyadh, Saudi Arabia. – Paratype. 1 worker, same data as the holotype ( KSMA) ( CASENT0922261 ).

Measurements of holotype (paratype in brackets): EL 0.25 (0.25); HL 1.25 (1.15); HW 0.90 (0.85); PNH 0.70 (0.60); PNL 0.45 (0.50); PNW 0.45 (0.45); PW 0.65 (0.60); SL 1.35 (1.35); TL 5.75 (6.00); WL 1.90 (1.85). Indices: CI 72 (74); DNI 100 (90); EI 28 (29); LNI 156 (120); SI 150 (159).

Description. Head. Slightly oval, longer than broad in frontal view, lateral margins converging posteriorly; posterior margin nearly straight in frontal view; antenna 12- segmented; scape long, extending beyond posterior margin of head by about one-third of its length; second funicular segment longer than third; in frontal view, eyes just breaking lateral sides of head in frontal view; eyes of moderate size, with a straight ventral margin and convex dorsal margin, and with 13 ommatidia in the longest row; in frontal view, mandibles subtriangular, but capable of closing tightly against the anterior margin of clypeus without a gap between them when apices overlap, and with a terminal tooth and a small basal dent; clypeus triangular with a distinct median carina and a prominent median lobe; anterior clypeal margin with a large translucent, fringing lamella. – Mesosoma. Metanotal groove deeply impressed; propodeal dorsum long, more than 2.5 x longer than descending face; metapleural gland orifice prominent. – Petiole. In profile, anterior face shorter than the posterior face and rounding to dorsum, which meets the posterior face at a right angle, posterodorsal angle not projecting posteriorly. – Sculpture. Mandible smooth and shining with scattered punctures; clypeus finely, longitudinally rugulose; cephalic surface smooth and shining with relatively pit-like punctures; promesonotum, mesonotum, and propodeal dorsum with few scattered pitlike punctures; metanotal groove cross-ribbed in dorsal view; meso-, metapleuron and descending face of propodeum transversally rugulose; petiole, and gastral tergites finely shagreened. – Pilosity. Body with long, yellow, stiff erect to suberect setae; antennae with appressed dense pubescence. – Colour. Black to brown-black; mandibles, antennae, legs, and tip of gaster brown.

Male ( Figures 2 )

A single male was collected by a pitfall trap in the type locality. This specimen is similar to the workers of L. polaszeki sp. n. in terms of body size, colour, sculpture and pilosity and appears to be the male caste of this species. However, a final confirmation is required.

Material: Asir Province: Abha, Raydah, Saudi Arabia, 18.02915˚ N, 42.389083˚ E, alt. 1614 m, 26.viii.2014 (Al Dhafer leg.), P.T. 3-3-5, KSMA (CASENT0922262). Measurements: EL 0.36; HL 0.92; HW 0.72; PNH 0.51; PNL 0.38; PNW 0.39; SL 0.28; TL 5.52; WL 1.92. Indices: CI 78; DNI 103; EI 50; LNI 134; SI 39 (n=1).

Description. Head. Longer than broad with strongly convex posterior margin in frontal view; antenna 13-segmented; scape short (SI 39); all funicular segments distinctly long- er than broad; eyes large (EL 0.5 x HW, EI 50), with a straight ventral margin and convex dorsal margin; in frontal view, mandibles reduced; clypeus broad, rectangular, with a feeble but distinct median carina. – Petiole. Like worker. – Sculpture. Mandible as worker; clypeus superficially, irregularly rugulose; cephalic surface as worker; in dorsal view, promesonotum and mesonotum finely longitudinally irregularly rugulose; propodeal dorsum transversely rugulose; petiole smooth and shining. – Pilosity. Like work- er. – Colour. As worker, but mandibles, antennae, legs, and tip of gaster yellow or yellow-brown.

Etymology. The species is named in honour of Dr. Andrew Polaszek (Natural History Museum, London).

Type locality ( Figure 3 ). The Raydah Nature Reserve is a part of the Asir Mountains and is located 10 km west of Abha City. The village of Raydah lies at 1600 m just outside the protected area. Raydah Nature Reserve has one of the last remnants of bushy juniper forests existing in Saudi Arabia, with a distinct altitudinal zonation of vegetation. The diversity of the vegetation cover of the region is exceptionally high including Juniperus procera (Cupressaceae) , Olea europaea africana (Oleaceae) , Lycium shawii roem (Solanaceae) , Aloe officinalis (Xanthorrhoeaceae) , Panicum turgidum (Poaceae) , Haloxylon salicornicum (Chenopodiaceae) , Maerua crassifolia (Capparceae) , Opuntia ficus-indica (Cactaceae) , Ziziphus spina-christi (Rhamnaceae) , Coffea arabica (Rubiaceae) and Acacia spp. ( Mimosaceae ).

Differential Diagnosis. Leptogenys polaszeki sp. n. is a member of the L. sulcinoda - group as defined by Bolton (1975) and cannot be identified using his key to Afrotropical species. L. polaszeki sp.n. is most similar to L. bellii Emery, 1901 from Ethiopia. The two species are uniformly black to brown-black with mandibles, antennae, legs, and tip of gaster brown. L. polaszeki has the metanotal groove deeply impressed in profile, whereas in L. bellii the metanotal groove is shallowly impressed. In addition, L. polaszeki has longer scapes (SI 150-159), lower dorsal petiolar node index (DNI 90-100), and lower lateral petiolar node index (LNI 120-156), versus (SI 122, DNI 127, LNI 171) for L. bellii . Moreover, L. polaszeki has smaller eyes, with 13 ommatidia in the longest row, while the eyes of L. bellii are larger, with about 21 ommatidia in the longest row. Superficially, L. polaszeki appears similar to L. elegans Bolton, 1975 from Nigeria, but it can be readily separated by the larger body size (TL 5.75-6.00; HL 1.15-1.25; HW 0.85-0.90), the longer scapes (SI 150-159), and the less abundant hair-pits on the body surface; while L. elegans has a smaller body (TL 4.50 -4.90; HL 0.96-1.02; HW 0.60 - 0.72), shorter scapes (SI 125-138), and abundant hair-pits on the body surface.

Key to species of the genus Leptogenys from the Arabian Peninsula

1 In frontal view, mandibles subtriangular and feebly curved, but capable of closing tightly against the anterior margin of clypeus without a gap be- tween them ( Figure 4 A); eyes smaller, with about 13 ommatidia in the longest row ( Fig. 4 A); in profile, petiolar node making a right angle with the straight posterior face ( Fig. 4 C); petiole as long as or little longer than broad in dorsal view ( Fig. 4 E); scapes long (SI 150 – 159) ........... L. polaszeki sp. n.

– In frontal view, mandibles elongate and curvilinear, not capable of clos- ing tightly against the clypeus ( Fig. 4 B), the apices leaving a large gap be- tween themselves and the clypeus when closed ( Fig. 4 B); eyes larger, with about 25 ommatidia in the longest row ( Fig. 4 B); petiolar node mak- ing a continuous curve with the convex posterior margin ( Fig. 4 D); peti- ole at least 1.5 x broader than long in dorsal view; scapes shorter (SI 101– 110) ............................................................................................. L. maxillosa (Smith)

Remarks. The relatively few specimens of Leptogenys known from this region may be due to the nocturnal activity of the species. Direct collecting methods such as hand picking are not as effective as pitfall trapping. Leptogenys polaszeki n. sp. seems to be a rare taxon since only two specimens were collected during extensive insect surveys near the type locality, including setting more than 200 pitfall traps bimonthly over two consecutive years.

Figures

Figure 1. SEM image of worker of Leptogenys polaszeki sp. n. 1 A. Head, mesosoma, and petiole in profile; 1 B. Head in frontal view; 1 C. Petiole and gaster in profile.

Figure 2. Automontage images of male of Leptogenys polaszeki sp. n. A. Body in profile; B. Head in frontal view; C. Body in dorsal view (CASENT 0922262) (Photograph: Michele Esposito).

Figure 3. Type locality: Raydah Nature Reserve.

Figure 4. Automontage images of Leptogenys polaszeki sp. n. and L. maxillosa: A. holotype worker of L. polaszeki sp. n., head in frontal view, CASENT 0 922261, B. L. maxillosa, Syntype worker, head in frontal view, CASENT 0102266 (photographer: April Nobile), C. holotype worker of L. polaszeki sp. n., body in profile, CASENT 0 922261, D. L. maxillosa, syntype worker, body in profile, CASENT 0102266, E. holotype worker of L. polaszeki sp. n. body in dorsal view.