Carasobarbus exulatus (Banister & Clarke, 1977)

Borkenhagen, Kai & Krupp, Friedhelm, 2013, Taxonomic revision of the genus Carasobarbus Karaman, 1971 (Actinopterygii, Cyprinidae), ZooKeys 339, pp. 1-53 : 17-19

Carasobarbus exulatus (Banister & Clarke, 1977)

Barbus exulatus Banister and Clarke 1977: 116.

Material.

Type material. Holotype of Barbus exulatus : BMNH 1976.4.7:299, Yemen, Wādī Ḩaḑramawt at Qasam (16°10'N, 49°4'E), W. A. King-Webster.

Paratypes of Barbus exulatus : BMNH 1976.4.7:308, 1; BMNH 1976.4.7:300-307, 8, same data as holotype. - BMNH 1976.4.7:328-329, 2; BMNH 1976.4.7:330-331, 2, Yemen, Wādī ‘Idim/Wādī Ḩaḑramawt at Ghuraf (16°0'N, 49°0'E), W. A. King-Webster. - BMNH 1976.4.7:309, 1; BMNH 1976.4.7:310-318, 9; BMNH 1976.4.7:319-327, 9, Yemen, Wādī Ḩaḑramawt at Ghayl 'Umar (15°44'N, 48°51'E), W. A. King-Webster. - BMNH 1976.4.7:332-333 probably Wādī Marrān in Wādī Aḩwar system [13°53'51"N, 46°05'14"E], G. Popov, 2 Aug 1962.

Non-type material. Wādī Ḩaḑramawt /al Masīlah drainage. BMNH 1976.5.17:9-10, 2, Yemen, Wādī al Khūn (16°10'N, 49°10'E). - SMF 33108, 10, Yemen, Wādī al Khūn (16°9'51"N, 49°6'2"E), F. Krupp et al., 3 Jun 2005. - SMF 33109, 17, Yemen, Wādī al Khūn (16°9'45"N, 49°4'46"E), F. Krupp et al., 3 Jun 2005. - SMF 33110, 14, Yemen, Wādī al Masīlah near Fughmah (16°8'36"N, 49°27'7"E), F. Krupp et al., 4 Jun 2005. - SMF 33111, 1, Yemen, Wādī al Masīlah at al Hind (15°44'53"N, 50°24'32"E), F. Krupp et al., 5 Jun 2005. - SMF 33106, 8, Yemen, Wādī 'Idim at Ghayl 'Umar near Arḑ ar Raydah (15°40'51"N, 48°51'59"E), F. Krupp et al., 2 Jun 2005. - SMF 33107, 11, Yemen, Wādī 'Idim near Ghayl 'Umar (15°40'10"N, 48°51'4"E), F. Krupp et al., 2 Jun 2005. -SMF 33105, 13, Yemen, Wādī Mara in Wādī Daw‘an system (15°8'36"N, 48°26'58"E), F. Krupp et al., 31 May 2005.

Diagnosis.

Dorsal fin with 9 branched rays in most specimens; last unbranched ray of dorsal fin as long as or longer than head; 2 pairs of barbels; 26 to 32 scales in the lateral line and usually 12 scales around the least circumference of the caudal peduncle.

Description.

The body is not particularly high backed and the maximum body depth is at the origin of the dorsal fin or slightly in front of it (Fig. 13). A nuchal hump is present in adult specimens (Fig. 14) but absent in juveniles (Fig. 15). The caudal peduncle is slender. The head profile is convex ventrally and straight dorsally. The body depth is about the same as the head length (Fig. 12). In specimens below 100 mm SL, the head is rather narrow, in larger specimens it becomes wider. The mouth is subterminal and comparatively narrow. Two pairs of barbels are present (Table 2), the posterior one is rather long. The eyes are at the end of the anterior half of the head and slightly protuberant. The morphometric characters are summarised in Table 1.

The dorsal fin is long and usually has four unbranched and eight to 10 branched rays (Table 3). The last unbranched ray is strongly ossified and only the tip is flexible. Its length is about the same as the head length (Fig. 4). The anal fin is long, usually has three unbranched and five or six branched rays (Table 4).

There are 26 to 32 scales in the lateral line (Table 5), 4 to 5.5 scales above the lateral line (Table 6), 3.5 to five scales below the lateral line (Table 7) and 10 to 12 scales around the least circumference of the caudal peduncle (Table 8). The scales are shown in Fig. 5.

The pharyngeal teeth count is 2.3.5-5.3.2 in one specimen, 2.3.5- in 16 specimens, -5.3.2 in one specimen and 2.3.4- in one specimen. The pharyngeal teeth are hooked at their tips (Fig. 6).

In live specimens and freshly preserved specimens the back and the sides are grey to golden, the belly is yellowish white and the fins are sometimes golden to orange (Fig. 15). Preserved specimens have a dark back and a lighter belly, the fins are whitish or greyish. Juveniles have a dark spot on the sides of the caudal peduncle.

The maximum length observed in the material available is 288 mm SL.

Carasobarbus exulatus differs from all congeners, except Carasobarbus fritschii and Carasobarbus harterti in modally having nine instead of 10 branched dorsal-fin rays. It differs from Carasobarbus fritschii and Carasobarbus harterti in modally having 12 scales around the least circumference of the caudal peduncle vs. 16 and in having 26 to 32 scales the lateral line vs. 30 to 39 and 31 to 38 respectively.

Distribution.

This species is endemic to Yemen and occurs in Wādī Ḩaḑramawt / Wādī al Masīlah and its pleistocene tributaries ( Banister and Clarke 1977, Krupp 1983a, Fig. 7). It is also known from Sadd Ma’rib ( Al-Safadi 1995), a dam lake at 15°23'46"N, 45°14'37"E and Wādī Ḩajr (14°02'42"N, 48°40'27"E), where they are "found throughout the whole year and are distributed all over the stream" ( Attaala and Rubaia 2005).

Locality data for BMNH 1976.4.7:332-333 is given as "Wadi Maran, E. Yemen" ( Banister and Clarke 1977), which is most likely Wādī Marrān [13°53'51"N, 46°05'14"E], representing the westernmost record of this species that is backed by specimens.

Habitats and biology.

The biology of this species is mostly unknown.

Conservation status.

During a field expedition in 2005 one of the authors saw large, continuous water bodies in the Wādī Ḩaḑramawt / Wādī al Masīlah area. The species is rated as "Endangered B1a, b; B2a, b" and water extraction is identified as the main threat ( BCEAW 2002).

Discussion.

Carasobarbus exulatus was described from Wādī Ḩaḑramawt and Wādī Maran in Yemen and placed in Barbus ( Banister and Clarke 1977). Later it was transferred to Carasobarbus ( Ekmekçi and Banarescu 1998).