First land snail records from Gebel Elba in southeastern Egypt — at the border between the Palaearctic and Ethiopian regions

A first land snail survey in the Gebel Elba massif in southeastern Egypt revealed the occurrence of just two taxa, Pupoides coenopictus and a second pupilloid species, probably a Truncatellina species.


INTRODUCTION
Gebel Elba is an igneous massif in southeastern Egypt, near the boundary with Sudan and approximately 20 km west of the Red Sea.This region is of special biogeographic interest because it is close to the border of the Palaearctic and Ethiopian regions and the proportion of Palaearctic and Ethiopian elements in this area has yet to be determined.The Gebel Elba massif and the area around it were declared a nature reserve in 1986 as Gebel Elba National Park.The climatic conditions in Gebel Elba are unique because the peaks, which rise to a maximum elevation of 1435 m, act as dew traps, where moist air from the Red Sea condenses and creates a "mist oasis".The moisture enables the existence of a diverse flora with 458 plant species (Kassas & Zahran 1971;Abd El-Ghani & Abdel-Khalik 2006;Al-Gohary 2008).Gebel Elba also supports a rich fauna including 36 reptile and amphibian species (Baha El Din 2006), 36 breeding bird species (Meininger & Goodman 1996), and 26 mammal species (Basuony et al. 2010).Unfortunately, little is known about the invertebrate fauna of this region.Among others, 28 arachnid species (El-Hennawy 2007), 13 neuropteran species (El-Hamouly & Fadl 2011), 30 butterfly species (Gilbert & Zalat 2007;El-Gabbas & Gilbert 2016), and 244 coleopteran species (including the Red Sea coastal region; Fadl & Hassan 1997) have been recorded.Until now, nothing was known about the occurrence of terrestrial molluscs on Gebel Elba.

MATERIALS AND METHODS
As a first contribution to the investigation of the terrestrial mollusc fauna, one of us (RFA) visited Gebel Elba on 4-5 December 2015 and studied 15 sites in valleys on the northern slopes of the mountains (Figures 1-2; Table 1).The coordinates (datum WGS 84) of the sites were determined with a GPS receiver.At each site snails were  searched for ca.30 min (0.5 person-hour) and a litter and soil sample (1-2 L) was taken.These samples were sieved and sorted in the laboratory.Identifications were made utilizing Pilsbry (1921) and Seddon (1992).All material was deposited in the Zoological Museum of the University of Hamburg, Germany (Table 1).

RESULTS
No large snails were detected in the field.Only two species were found, both from the litter/soil samples (Table 1).
Pupoides coenopictus is the only species of the genus occurring in northern Africa.It was found at four of the 15 sites, although unribbed shell fragments that most probably are also this species, were recovered from samples taken from two additional sites (Table 1).Most of the shells were empty, but two specimens were collected alive.

Family Truncatellinidae
Truncatellina (?) sp. Figure 4 One apical fragment of a ribbed pupilloid species was found (Table 1), which agrees with Truncatellina Lowe, 1852 with regard to size, form and sculpture.

DISCUSSION
Pupoides coenopictus is widespread in arid regions from the Cape Verde Islands in the west through northern and eastern Africa, the Middle East to Afghanistan, Tajikistan, Pakistan, India, and Sri Lanka (Pilsbry 1921;Schileyko 1984;Seddon 1992;Verdcourt 2006).In Egypt the species has been recorded from Al Matariyah (Dakahlia governorate), Cairo, and Wadi Hawf near Helwan (Cairo governorate) in northern Egypt by Pallary (1909) and from Sidfa and Abo-Tij (Asyut governorate) by Ramzy (2009).It is probably widespread in Egypt.
Truncatellina is widespread throughout both the Palaearctic and the Ethiopian region.However, it has not been recorded from Egypt previously.The geographically closest occurrences of Truncatellina species are known from Eritrea, Saudi Arabia, and Israel (Pilsbry 1920(Pilsbry -1921;;Heller 2009;Hausdorf & Wronski 2011).
Although the discovery of Pupoides coenopictus and Truncatellina sp. in Gebel Elba is not surprising from a biogeographical perspective, it is the first evidence that the climatic conditions allow the existence of terrestrial snails in Gebel Elba.This raises hope that additional, ecologically more demanding snail species might be found in the moister zone at higher elevations of Gebel Elba analogous to the richer snail fauna that has been found at higher elevations of the escarpment of the mountains bordering the opposite coast of the Red Sea in Arabia (Neubert 1998;Hausdorf & Wronski 2011).

CheckFigure 1 .
Figure 1.Sampling sites in the Gebel Elba region, Egypt.Figure2.Small wadi on the northern slopes of Gebel Elba.

Figure 2 .
Figure 1.Sampling sites in the Gebel Elba region, Egypt.Figure2.Small wadi on the northern slopes of Gebel Elba.

Table 1 .
Sampling sites in the Gebel Elba region.Sites 1-2 are in Wadi Aideib and Sites 3-15 are in a small northwest-facing side valley.The unribbed shell fragments most probably belong to Pupoides coenopictus.ZMH: Zoological Museum of the University of Hamburg.