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Nesomyrmex angulatus (Mayr)

Nesomyrmex angulatus (Mayr)

return to key  Type location Egypt (Leptothorax angulatus n. sp., Mayr, 1862: 739, worker)  from Sinai Peninsula, by R v Frauenfeld - see below
subspecies lybica (Leptothorax (Goniothorax) angulatus var. lybica n. var., Menozzi, 1934: 155, worker) from Libya, Cufra - no images on Antweb (March 2019).
junior synonym ilgii (Leptothorax angulatus Mayr, r. Ilgii, n. stirps, Forel, 1894b: 82, worker; Santschi, 1912c: 148, queen) from Ethiopia, Sudabessinien, Ilg; see Bolton (1982: 324, illustrated; Bolton, 1995) - see below
Genus name change by Bolton (2003: 249) .

Mayr's (1862) description is at {original description}. Forel's (1894b) description of ilgii is at {original description}. Mayr's (1895) description of latinodis is at{original description} Menozzi's (1934) description of lybica is at {original description}. Bolton's modern description (1982) is at {original description}
On the ilgi queen, Santschi (1912c), wrote: Leptothorax angulatus Mayr stirps ilgi For., queen undescribed, TL 3.8 mm, alitrunk much darker than that of the worker; scutellum sculptured as the rest of the alitrunk, the propodeal spines and rest as the worker.

For the following reasons, I prefer to revert to the original status determined by Mayr and revert Nesomyrmex latinodis to full species status, with probable junior synonym concolor (Santschi, 1914b: 107, illustrated, worker; Emery, 1915g: 16, queen & male) from Kenya.

In his 1982 paper and his other revisionary works, Bolton adopted a curious approach to his analyses. There are instances where, when dealing with what he decided to describe as new species, relatively small characteristics were deemed significant. When dealing with the work of the early authors, notably Forel and Santschi, he commonly adopted the obverse tactic and wrote of variations in colour, size and morphology as not justifying separation of forms (subspecies, varieties, strips, etc) and made sometimes substantial synonymization of such forms.

In the instance of N. angulatus he took all specimens he examined from sub-Saharan Africa as meeting the characters of the type form from Egypt (noting that he had examined a lectotype worker from the original collection, Mayr, 1862). It seems curious that Bolton, who had not been able to sight latinodis should have ignored the simple fact that it was Mayr, an obviously very accurate and cautious worker, who described both species.

With the Antweb images of a cotype from Tunisia and the type of ilgii, together with the fresh specimens from Egypt (Bolton does not report sighting any specimens other than the lectotype he designated), Sudan and Benin, plus the Mike Lush photomontage (below) of a coastal scrub specimens from Gambia, I show below the type form. These can be contrasted with most sub-Saharan specimens, as drawn by me from life in Nigeria and the photomontage of specimens from Tanzania - on Nesomyrmex latinodis.

1. In full face view, the North African specimens have heads which narrow from occiput to anterior and very much so anterior to the eyes (however, not to the extent shown in Bolton's drawing). The sub-Saharan specimens have heads which are near parallel throughout their length.
2. The sculpturation of the head and ailtrunk is much less prominent in the North African specimens.
3. The petiole of the North African specimens is noticeably shorter and more rounded in both lateral and dorsal views; and, does not have very distinct sharp anterior and dorsal margins.
4.The postpetiole of the North African specimens is only slightly wider than the petiole and has no more than weak sculpturation; whereas the postpetiole of the Tanzanian specimens can be seen to be some 50% wider than the petiole, more angular and to have strong sculpturation.
5. The erect pilosity on the North African specimens is quite fine; whereas it is much coarser on the sub-Saharan specimens.

My conclusion is that, if viewing the specimens without prior knowledge, it seems a strong likelihood that the North African and most sub-Saharan populations compose at least two distinct species. Despite the wide distribution of "Nesomyrmex angulatus" specimens are not common and a firmer decision is unwise at present.

Santschi noted that Forel's ilgii (1894b) was consistently darker than the type form; ilgii has the same shape of head, etc., as the type angulatus.

Collingwood (1985) reporting it from Saudi Arabia (with a relatively poor sketch), noted it as extending northward to the Middle East; it was found mostly in old dead wood of Acacia.

North African and Sahel - type location populations

{Nesomyrmex angulatus}The photomontage of the type from Egypt is collated from

{Nesomyrmex angulatus}The photomontage of a cotype from Tunisia is collated from .

{Nesomyrmex angulatus}The photomontage of the type of ilgii is collated from

Oxford University Museum specimens - see also others from Benin and Sudan on Ants of Africa

Nesomyrmex angulatus
B Taylor det.
M Sharaf

El Mansourah
3110' N
3135' E


{Nesomyrmex angulatus}The photomontage is of a worker from Egypt, Talkha (El-Mansoura), 13.vii.2003, collector Mostafa Sharaf. 

Nesomyrmex angulatusThe photomontage is of a worker from Sudan, collected by J Mathews, by pyrethrum fogging of Acacia senegal; Abu Gmein, Blue Nile - 1121' N 3427' E; 25.xi.2001; JM 174, 2 workers, 6 unmounted; 2 other trees unmounted workers.

2005, 2006, 2015, 2019 - Brian Taylor CBiol FRSB FRES
11, Grazingfield, Wilford, Nottingham, NG11 7FN, U.K.