Genus Crossocheilus
Kuhl and van Hasselt in van Hasselt, 1823

Kottelat (1987) retains the spelling Crossocheilus Kuhl and van Hasselt in van Hasselt, 1823 as first reviser. The name was spelt Crostocheilus early in the text but this has never been used again and Crossocheilus appeared with the description. Crossochilus Günther, 1868 is an incorrect emendation (Eschmeyer, 1990).

The genus is found chiefly in the Oriental Region but extends into Iran with one species. There are about 18 species.

The genus is characterised by an elongate body with a rounded belly; the mouth is inferior and transverse, the crenulated or fringed upper lip being continuous with the snout (not separated by a groove); the lower jaw has a horny covering and behind this are several rows of lobate papillae; 1-2 pairs of barbels; gill membranes attached to isthmus; dorsal and anal fins are short and spineless; the lateral line is complete; scales are large to moderate in size; the intestine is very long; and the peritoneum is black.

The lower surface of the head bears an "adhesive apparatus", the mechanism of which has been investigated by Singh (1993) for Crossocheilus latius latius, a subspecies not found in Iran. The fringed upper lip acts as a food strainer as well as part of the adhesive apparatus. Both this lip and the area behind the lower lip are heavily tuberculate with glandular openings and irregularly arranged hard ridges. Mucus from the glands in conjunction with the ridges holds the fish to the substrate.

Crossocheilus latius
(Hamilton-Buchanan, 1822)

Common names

None.

[ispigoar or dogra in Pakistan].

Systematics

Cyprinus latius was described from the Tista River in India/Bangladesh and types are unknown (Eschmeyer et al., 1996).

Bianco and Banarescu (1982) and Bănărescu (1986) consider Discognathus adiscus Annandale, 1919 described from Sistan (type locality given below) to be a synonym of this species which is represented in Sistan and Baluchestan by Crossocheilus latius diplocheilus (Heckel, 1838), originally described from Kashmir with syntypes in the Naturhistorisches Museum Wien under NMW 48820 (7 fish). Bănărescu (1986) cites 1 fish under NMW 48420 as possibly the holotype but this specimen is dated 1839 which is anachronistic. Berg (1949) considers Discognathus adiscus to be a distinct species. I concur with Bianco and Banarescu (1982) and Bănărescu (1986).

Characters advanced by Berg (1949) for separating the two species are number of barbels (4 in adiscus, 2 in latius diplocheilus where mouth angle barbels are absent or rudimentary, not the rostral ones as implied by Bianco and Banarescu (1982)), upper lip fringe (barely developed in adiscus, distinctly developed in latius diplocheilus), the posterior swimbladder (conical in adiscus, elongate cylinder in latius diplocheilus), and papillae on the lower lip and chin (rudimental in adiscus and latius diplocheilus but the latter has almost free lateral edges and an attached posterior end - this condition is not specified for adiscus). Bianco and Banarescu (1982) and Bănărescu (1986) found some latius diplocheilus specimens to have 4 barbels (and this is given too as a character of C. latius latius), and no difference in development of lip papillae in specimens from the Indus River basin (actually my reading of Berg (1949) cited above does not indicate that papillae development differs but that the sucker area has almost free lateral edges and an attached posterior end; this occurs in Sistan fish but not in 4 fish from the Mashkid and Makran basins of Iran which have a fold in the flesh behind the tuberculate area - these latter fish are very small however, 20.8-27.8 mm standard length, and I lack extensive comparative adult material from outside the Sistan basin in Iran and from neighbouring Pakistan to make an adequate analysis of nominal adiscus and latius diplocheilus in this and other characters). My observations of the posterior swimbladder development indicate a great individual variation in form for Sistan fish: the swimbladder may be conical, elongate and tapering, rounded posteriorly, expanded posteriorly, rounded posteriorly after a constriction, or even a narrow elongate cylinder supposedly characteristic of latius. Fringe development of the upper lip is also quite variable and seems to be relatively well-developed in larger Sistan fish.

Karaman (1971) described a new genus, Hemigarra, for Tylognathus elegans Günther, 1868 and Discognathus adiscus Annandale, 1919. He places Crossocheilus adiscus as the Sistan subspecies of his Hemigarra elegans (= Hemigrammocapoeta elegans here, q.v.) which is found in Mesopotamia. Karaman (1971) distinguishes the two subspecies by the former having densely arranged papillae on the chin as opposed to sparse papillae. Bianco and Banarescu (1982) and Bănărescu (1986) state that it is not related to Hemigrammocapoeta elegans but is a typical Crossocheilus species.

The type locality of Discognathus adiscus is Sistan by implication, as no locality is given for the holotype in Annandale (1919b). Menon and Yazdani (1968) concur. Distribution is given as "small watercourses and pools in the plains of Seistan" and "Nasratabad, irrigation channel in Consulate garden; pool in the desert 5 miles south of Nasratabad; pools in stream-bed 12 miles north of Nasratabad; channels in the reed-beds of the Hamun-i-Helmand near Lab-i-Baring, and channel leading out of the Hamun 12 miles east of Lab-i-Baring; small watercourse, Lutak, southern Seistan", and one of these is presumably the type locality.

Twenty syntypes of Discognathus adiscus are in the Zoological Survey of India, Calcutta (ZSI F9758/1) (Menon and Yazdani, 1968). Annandale (1919b) cites ZSI 9763/1 as the holotype catalogue number. Three syntypes are in the Zoological Institute, St. Petersburg (ZISP 25411) from "Nasratabad, Seistan, Indian Museum, Dr. Hora" and measure 38.0-43.4 mm standard length. Two syntypes (listed as cotypes) measuring 44.8-45.5 mm standard length from "Jellalabad" with the annotation "Ind. Mus. Ex. F 9762/1" are in the Natural History Museum, London (BM(NH) 1919.8.16:7-8; the outside has 1919.3.16:7-8, incorrectly).

Key characters

The characters of the genus, particularly in the mouth region, serve to identify the only species in Iran.

Morphology

Four short barbels are present, the rostral ones longer than those at the mouth corner. The upper lip covers the upper jaw, is granular or tuberculate and has a marginal fringe, variably developed and most apparent in larger fish. The lower lip is only apparent at the sides and the exposed lower jaw has a granular or tuberculate pad without a free posterior margin but with almost completely free edges.

Dorsal fin with 2-3 unbranched and 8-9 branched rays, anal fin with 2-3 unbranched and 5 branched rays, pectoral fin branched rays 14-17, and pelvic fin branched rays 7-9. Lateral line scales 33-39. Scales may have short dorsal and ventral projections from the margin at about one-third of the scale length from the posterior edge. There is a pelvic axillary scale. Scales have 9-10 radii on the posterior field and are elongate with a notably anterior focus. Radii in large fish are parallel rather than divergent. The anus is 4-5 scales in advance of the anal fin origin. Gill rakers 17-25, small reaching the adjacent or second raker when appressed. Pharyngeal teeth usually 3,3,5-5,3,3 or 2,4,5-5,4,2, depending on how the crowded teeth are counted; major row teeth are usually 5 but may be 4 or 6, middle row teeth are 3 or 4, and minor row teeth 2 or 3, more rarely 1 (this difficulty in assigning teeth to rows is the reason for omitting frequency distributions below). Supernumerary teeth may be present to further confuse counts. The crown of major row teeth are flattened, the anterior tooth may be rounded and some teeth may have a small hooked tip. The gut is very long and complexly coiled. The chromosome number is probably 2n=48 (Klinkhardt et al., 1995).

Iranian fish from Sistan and Baluchestan have the following meristic characters: dorsal fin branched rays 8(81) or 9(1), anal fin branched rays 5(81), pectoral fin branched rays 14(28), 15(37), 16(16), or 17(1), and pelvic fin branched rays 7(3), 8(76), or 9(3). Lateral line scales 33(1), 34(2), 35(12), 36(31), 37(32) or 38(4). Total gill rakers 20-25, but not countable with great accuracy since the smallest rakers are difficult to detect at the ends of the arch. Total vertebrae 34(6), 35(20), 36(9) or 37(1).

Sexual dimorphism

Unknown.

Colour

The back is bluish-grey in Sistan fish or brownish to greenish with irregular spots in other populations and the belly light pink to yellowish-white or silvery-white. Fins are pink and the dorsal and caudal fins have a grey tinge. The flank has a bluish, mid-lateral stripe in Sistan fish and in preserved ones scattered melanophores, or small blotches of less than scale size, or clumps of melanophores centred on upper flank scales and more dispersed on the lower flank. There is a broad stripe along the back mid-line. Fins in preserved fish from Sistan are mostly immaculate except in the larger fish with some melanophores lining rays basally. The caudal fin is distinctive in larger fish from Sistan in having the rays of the lower half of the fin heavily pigmented while the upper half rays are only lightly pigmented. Peritoneum is dark brown to black.

Size

Attains 14.6 cm although the largest fish recorded from Sistan was 93.2 mm standard length.

Distribution

Found in submontane areas of Afghanistan, Pakistan and India as well as eastern and southeastern Iran. The main areas of distribution are Sistan, the Mashkid River basin including the Simish River and coastal streams of Makran from the Jagin to middle and upper Nikshahr rivers and the middle and upper Bahu Kalat River including its Sarbaz River reach. (Nikol'skii, 1899; Annandale, 1919b; Berg, 1949; Bianco and Banarescu, 1982; J. Holčík, in litt., 1996; Abdoli, 2000).

Zoogeography

This distribution in Iran marks the western limit for the genus and the relationships of the species lie to the east.

Habitat

Very abundant in small streams, including those with rocky or muddy beds, irrigation ditches, channels in reed beds and pools in Sistan, less common in Baluchestan streams. This species is found in large schools in Sistan in still or slow-flowing water, on the bottom during the day but it may swim at the surface in the evenings. It is common in the smallest permanent water channels but Annandale and Hora (1920) reported it to be in small numbers in the reed beds in winter and these were dead or dying, perhaps because of low oxygen conditions associated with vegetation decay. Large numbers die each year in drying stream beds as salt content increases and the water is fouled by sheep and goats. Tekrival and Rao (1999) report its aquarium preferences as 18-22°C, pH 6.5-7.2, algae as food, not too bright lighting, bottom dwelling with stones, roots and crevices preferred and cave brooding reproduction.

Age and growth

Unknown.

Food

Diet is algae on muddy bottoms. The type subspecies is a bottom feeding herbivore taking more than 90% plant food such as algae, diatoms and macrophytes as well as detritus (Sharma, 1984; Singh and Bahuguna, 1984). Iranian fish contain detritus and some insect remains, possibly as accidental inclusions.

Reproduction

Iranian adult specimens were caught in May in Sistan and show signs of developing reproductive organs suggestive of summer spawning.

Parasites and predators

Jalali et al. (2000) describe two new species of monogenean, Dactylogyrus faridpaki and D. eslamii, from this species in the Bahu Kalat River of Baluchestan.

Economic importance

This species is of no economic importance although Butt (1995) suggests it could be cultured as food and as a forage fish in Pakistan.

Conservation

This species does not appear to be under any major threat as it can survive drying of the Sistan lakes in small ditches and streams.

Further work

The biology of this species needs investigation as does the taxonomic status of Sistan populations.

Sources

Mirza (1972) for colour.

Type material: See above, Discognathus adiscus (ZISP 25411, BM(NH) 1919.8.16:7-8).

Iranian material: CMNFI 1979-0224, 8, 43.6-55.4 mm standard length, Sistan, effluent of Hirmand River (30º53'30"N, 61º27'E); CMNFI 1979-0226, 277, 29.7-78.8 mm standard length, Sistan, pool near Kuh-e Khajeh (30º57'N, 61º17'E); CMNFI 1979-0227, 4, 37.0-48.9 mm standard length, Sistan, naizar at Kuh-e Khajeh (30º57'N, 61º16'E); CMNFI 1979-0228, 1, 42.9 mm standard length, Sistan, ditch 1 km from Zabol (31º02'30"N, 61º31'E); CMNFI 1979-0229, 5, 52.3-93.2 mm standard length, Sistan, ditch 5 km from Zabol (31º03'N, 61º33'E); CMNFI 1979-0230, 1, 48.3 mm standard length, Sistan, Hamun-e Puzak (ca. 31º15'N, ca. 61º42'E); CMNFI 1979-0232, 9, 44.0-65.9 mm standard length, Sistan, ditch 11 km from Zabol (ca. 30º58'30"N, ca, 61º36'E); CMNFI 1979-0234, 17, 40.4-49.3 mm standard length, Sistan, effluent of Hirmand River (30º54'N, 61º40'E); CMNFI 1979-0318, 2, 24.0-27.8 mm standard length, Baluchestan, Sarbaz River at Huvar (26º09'N, 61º27'E); CMNFI 1979-0333, 2, 20.8-21.2 mm standard length, Baluchestan, Mashkid River west of Kuhak (ca. 27º05'N, ca. 63º12'E).

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