Solenopsis cooperi Donisthorpe

Sharaf, M. R., Taylor, B. & Klingenberg, C., 2009, Ants of the genus Solenopsis Westwood, 1840 (Hymenoptera: Formicidae) in Egypt with a description of the worker castes of S. cooperi Donisthorpe, 1947., Zootaxa 2004, pp. 49-58 : 51-54

Solenopsis cooperi Donisthorpe , 1947

(Plate 1)

Solenopsis cooperi Donisthorpe , 1947: 110. Holotype gyne and paratype gynes and males, EGYPT: Siwa, 15 & 24.v.1935 (J. Omer-Cooper) ( BMNH) [examined]. Solenopsis bakri Sharaf in Fadl, 2007: 242. Holotype worker, one alate gyne, one male and syntype workers, EGYPT: Saloga Islands, Aswan, 2.vi.2002 (MostafaR. Sharaf) ( EESC) [examined]. Syn.n

Worker. TL 1.53-1.76, HL 0.41-0.56, HW 0.34-0.45, SL 0.25-0.35, EL 0.02, AL 0.42-0.62, PL 0.12-0.21, PW 0.12-0.17, PPL 0.10-0.14, PPW 0.08-0.17, SI 73-77, CI 80-83 (12 measured).

The workers examined could be divided into two size groups, suggesting dimorphism. Worker dimorphism has not been reported for Egyptian Solenopsis , but it is known for S. orbula from Corsica (Emery, 1916). Both major and minor workers were collected from a nest in association with gynes and males. Both groups of workers have a similar head shape, especially the flattened profile. The morphological differences are as follows:

Minor worker (Plate 1, Fig. a, b. c). Head relatively long and narrow, with a distinctive narrow profile; CI ca. 78. Mandibles quite narrow with only moderate teeth, the apical tooth somewhat elongated. Clypeus with a weakly impressed anterior margin and distinct but not sharp carinae. Frontal lobes set quite far apart. Frontal notch distinct. SI ca. 80. Head smooth and shiny with very minute hair pits. Promesonotum with a smooth profile, anteriorly rounded but posteriorly flat. Metanotal groove distinct, quite shallow and continuous dorsally. Propodeum with a distinctive dorsal longitudinal impression and posteriorly terminating in angular corners. Propodeal spiracles vertically ovoid and facing posteriorly. Petiole anterior peduncle short and narrow; viewed from above this is quite distinct. Petiole node quite high and narrow. Body with relatively few scattered short hairs. Overall colour dusky yellow, with the posterior of the gaster darkened.

Major worker (Plate 1, Fig. d, e, f). Head smooth with widely scattered but distinct hair pits; CI ca. 80. Mandibles narrow. Clypeus with only a weakly impressed anterior margin and very weak carinae. Frontal lobes set moderately far apart. Scape with a narrow base broadening after the mid-point and widest at about the two-thirds point, SI ca. 70. Promesonotum profile smooth and uninterrupted, almost flat posterior to the anterior convex half of the pronotum. Metanotal groove distinctly impressed. Propodeum with a small circular spiracle. Petiole node quite low with a domed profile. Gaster distinctly lighter than rest of the body. Overall with sparse, fine, relatively short, erect hairs.

The workers are readily distinguished from the known circum-Mediterranean species by the long peduncle to the petiole; the relatively high, narrowly rounded petiole profile; the proportionally longer head which is flattened in lateral view; and the angular, near dentate and longitudinally weakly furrowed propodeal dorsum.

Gyne (Plate 1, Figs g, h, i). Paratype. TL 4.0, HL 0.75, HW 0.55, SL 0.50, EL 0.15, AL 1.0, SI 91, CI 73 (1 measured).

Additional material: TL 4.50-4.75; HL 0.75; HW 0.57-0.60; SL 0.47-0.475; EL 0.17-0.20; AL 1.15; SI 78-83; CI 79 (2 measured).

The large ocelli are very distinctive compared to the other circum-Mediterranean species.

Male (Plate 1, Figs j, k, l). Paratypes. TL 3.0, HL 0.35-0.45, HW 0.40-0.45, SL 0.10, EL 0.25, AL 1.10-1.25, SI 22-25, CI 100-114 (3 measured).

Additional material. TL 3.0-3.6, HL 0.45-0.50, HW 0.40-0.52, SL 0.075-0.20, EL 0.17-0.25, AL 1.05-1.22, SI 21-43, CI 89-104 (7 measured).

The newly collected specimens appear to match the rather short description of S. cooperi given by Donisthorpe (1947), i.e. notably being brown, smooth & shining, with pale yellow appendages. The large ocelli also appear to be distinctive compared to the other circum-Mediterranean species.

Solenopsis cooperi has remained little known since the description by Donisthorpe (1947) when only the gynes and males were collected from Siwa Oasis in the western desert (previously known as the Libyan Desert). It appears to be restricted to Egypt. During two field trips carried out by the first author to Saloga Island Protectorate (located in the River Nile in Aswan) and to Abu-Swelam village (El-Minyia Governorate, Upper Egypt), many workers, males and two alate gynes were collected. These were mistakenly described as a new species by Sharaf in Fadl (2007). By comparing the sexual castes collected with the type material deposited in the ant collection of the British Museum of Natural History, we have confidence in our description of the associated workers and our further notes on the sexuals. Thus, the worker caste of S. cooperi is described for the first time and measurements of all castes are given.

Very little is known of the biology of S. cooperi , except for the colony from which our specimens were collected. This colony was small and in loose sandy soil at the base of an old tree. It is likely the species has a broad distribution and may be present at many other localities in Egypt or North Africa, especially in the Nile Valley and its islands, because the abundance of transport on the Nile ensures no place can be considered isolated. In addition, a single worker specimen was collected from Abu-Swelam village in the Nile valley far from Aswan. The original finding (Donisthorpe, 1942) at Siwa Oasis also is a long way from the Aswan location of the second finding.

Material examined. 32 workers, 2 $, 7 S; Egypt, Saloga Islands Protectorate, Aswan (Upper Egypt), 2.v.2002; 24.05° N; 32.56° E (M. R. Sharaf); 1 worker, Abu-Swelam (El-Minyia Governorate, Upper Egypt), 29.vi.2003; 28.06° N; 30.45° E (M. R. Sharaf). Three workers were deposited in BTC; five will be placed in the EESC; two will be at SMNK and the remaining workers in SHC.

Previous records. Burg El-Arab (Alexandria), 20.iii.1956 (ALFC); Burg El-Arab (Alexandria), 20.iii.1956 (AINC) (Mohammed, 1979; based on sexuals only).