Genus Proterorhinus
Smitt, 1900

This genus is characterised by having 6 first dorsal fin rays, a pelvic disc without obvious lateral lobes and, uniquely in Ponto-Caspian gobies, a very elongate anterior nostril which hangs over the lip. Miller in Miller (2004) give additional characters, in particular the distribution of neuromasts on the head. It contains only a single species found in the Black and Caspian seas and their tributary rivers and in the northern Aegean Sea in Greek fresh waters. There may be two species if P. semilunaris is recognised (see below). Simonovič (1999) considered this genus to be a subgenus of Neogobius but Ahnelt and Duchkowitsch (2001) provisionally consider Proterorhinus to be distinct based on their study of the lateral line system and consider it distinct based on osteology (Ahnelt and Duchkowitsch, 2004). Miller in Miller (2004) recognises the genus as distinct as do Stepien and Tumeo (2000) based on mtDNA. Simonovič et al. (1996) consider this genus of gobies to be a young one as evidenced by the distribution of the species in the Caspian Sea which closed recently.

Reshetnikov et al. (1997) and Miller in Miller (2004) have the date for this genus as 1899 but Eschmeyer's "Catalog of Fishes" states that it was published in 1900 although dated 1899.

Proterorhinus marmoratus
(Pallas, 18l4)

Common names

gav mahi, sag mahi, gel-ye mahi marmari, gavmahi-ye marmari, sebele.

[marmar xul in Azerbaijan; bychok-tsutsik or tubenose goby, marmornyi bychok or marbled goby, both in Russian; mottled goby].

Systematics

Gobius marmoratus was originally described from Sevastopol, Ukraine, on the Black Sea. Types are lost (Miller in Miller, 2004).

Gobius nasalis De Filippi, 1863 described in Latin from the "Mar Caspio presso Baku" and Gobius blennioides Kessler, 1877 described from "Bakinskoi bukhte" (= Baku Bay), are synonyms. The meristic characters reported by De Filippi (1863) for nasalis are probably in error according to Berg (1948-1949) but the only character falling outside the ranges compiled below is for soft dorsal rays given as 21. Gobius semipellucidus Kessler, 1877 is a synonym as this species shows considerable variation in body shape and fin ray counts (Il'in, 1956). It was described from a single specimen taken at the "ust'e rechki Kara-su, vpadayushchei vb Astrabadskii zalivb" (= mouth of the Karasu River falling into Astrabad Bay (Qareh Su, Gorgan Bay) and the holotype is in the Zoological Institute, St. Petersburg (ZISP) (Eschmeyer et al., 1996). The subspecies Proterorhinus marmoratus nasalis Berg, 1933 is not recognised.

Stepien and Tumeo (2006) used mtDNA cytochrome b sequence data and consider there are two species in this genus. P. marmoratus is a marine species in the Black Sea and P. semilunaris (Heckel, 1837) is a freshwater species in other Eurasian habitats. The type locality of the latter is "Maritza [Marizza] R., near Plovdiv, e. Rumelia, Balkan region of Bulgaria". Caspian Sea basin Proterorhinus have not been investigated. Kottelat and Freyhof (2007) and Freyhof and Naseka (2007)  restrict marmoratus to brackish waters in Sevastopol and consider nasalis to be the name for Iranian Caspian Sea populations.

The syntypes of Gobius nasalis are in the Istituto e Museo di Zoologia della R. Università di Torino under MZUT N.672 (7 specimens), the Natural History Museum, London under BM(NH) 1869.3.4:34 (1, 43.4 mm standard length), in the Museo Civico di Storia Naturale di Genova under MSNG 12655 (2) and MSNG 36228 (3), in the Naturhistorisches Museum Wien under NMW 33894 (1), NMW 33895 (1) and NMW 33896 (1), and in the Museum für Naturkunde, Universität Humboldt, Berlin under ZMB 5015 (3) (Eschmeyer et al., 1996; Miller in Miller, 2004; 43.3-48.4 mm standard length, measured in February 2006). Ahnelt and Mikschi (2008) give details on the types of Gobius semilunaris.

Key characters

The combination of the pelvic fins forming a disc, the head not being flattened, and the anterior nostrils forming a tube overhanging the upper lip are distinctive. The origin of the first dorsal fin is displaced anteriorly in comparison to other Ponto-Caspian and Atlantic-Mediterranean gobioids, and this reflects the differing postcranial osteology detailed in Ahnelt and Duchkowitsch (2004).

Morphology

First dorsal fin spines 5-7, usually 6, second dorsal fin with 1 spine and 12-20, usually 16-17, soft rays, anal fin with 1-2 spines and 11-17, usually 13-14, soft rays, and pectoral fin with 14-16 branched rays. Scales in lateral series 34-53. Scales are a vertical oval with the anterior margin rounded to slightly wavy, the upper and lower margins rounded and the posterior margin with almost straight upper and lower elements coming almost to a central point. This causes the exposed portion of the scales to be delimited by almost straight edges and flank scales have a diamond pattern. Circuli are numerous and fine. Radii are numerous and radiate back from a focus almost at the posterior margin. The posterior scale margin bears fine ctenii. Gill rakers 3-6, short and concentrated around the angle of the gill arch. A membrane partly closes off and narrows the gill opening at the gill raker level and may partially encompass a raker making counts difficult. Vertebrae 30-33. The chromosome number is 2n=46, with 46 acrocentric chromosomes and 46 chromosomal arms (Ráb, 1985; Grigoryan and Vasil'ev, 1993; Simonovič, 1999). The predorsal area on the back and the nape are scaled. The cheek has infraorbital neuromast organs in 7 transverse rows from the lower orbit border without uniserial papillae between the rows. The preopercular canal has three pores, the anterior oculoscapular canal has 7 pores and the posterior oculoscapular canal has 2 pores. Ahnelt and Duchkowitsch (2001) give a detailed description of the lateral line system on the head. The gut is short and s-shaped. The genital papilla has a two-lobed tip.

Freyhof and Naseka (2007) note that Caspian tubenose gobies are most similar to P. semilunaris (Heckel, 1837) of the Aegean and Black seas basins and are distinguished by having a shorter posterior membrane to the first dorsal fin, not reaching the origin of the second dorsal fin (versus reaching), a longer anterior naris reaching to the middle or to the lower margin of the lower lip when folded down (versus to the upper lip or to the upppermost margin of the lower lip), and a smaller eye (diameter 16-21% head length versus 20-28%).

Meristic values for Iranian specimens are:- first dorsal fin spines 5(1), 6(28) or 7(1); second dorsal fin soft rays 13(1), 14(6), 15(17) or 16(6); anal fin soft rays 12(13), 13(14), 14(2) or 15(1); total pectoral fin rays 14(18) or 15(12); lateral series scales 36(1), 38(4), 39(7), 40(7), 41(4), 42(5), or 44(2); total gill rakers 3(18), 4(9) or 5(3), although accuracy is doubtful because of the membrane; and total vertebrae 33(10), 34(16) or 35(3).

Sexual dimorphism

Males are overall darker than females, e.g. one at 60.1 mm standard length had pigment on both rays and membranes of fins, and all fin margins frilly and pale or orange-yellow. Cheeks are swollen in spawning males and fins are longer than in females.

Colour

Overall colour is brownish or yellowish-brown to olive or yellowish-green with about 5 oblique and irregular bars or blotches across the flank. Colour varies with the background, being darker on mud bottoms and a bright reddish-brown on sand. The head has brown-grey bands over the top and sides on a pale background. The first dorsal fin may have a pinkish tinge and irregular grey blotches. The second dorsal fin has several series of brown spots with the upper 2-3 greenish-yellow. The caudal fin is grey interrupted by up to 9 narrow bands of greenish-yellow. There is a triangular black spot at the caudal fin base, flanked by two white spots. The pectoral fin is similarly greyish with 5-7 narrow bands of pale green or yellow. The pelvic fin has 3-4 yellow bands and the anal fin 6-7 yellowish and oblique bands over a grey background. The iris has a narrow golden ring. Spawning males have all fins dark, although the pectoral fin is lighter than the rest and the caudal fin has an obvious white margin. The genital papilla is grey. Breeding females have a colour similar to that of both sexes in winter. Young (16-22 mm) have an unpigmented median band, wider than the eye, from the head to the first dorsal fin and even to the caudal fin. In front of the first dorsal fin is a dark saddle. The peritoneum is light brown to silvery with varying amounts of melanophores.

Size

Attains 15.0 cm although Caspian specimens reputedly reach only 7.6 cm.

Distribution

Found in both the Black and Caspian Sea basins, the northern Aegean Sea and the Uzboi Valley of Turkmenistan. Introduced to the Aral Sea and the Lake St. Clair in the American Great Lakes.

It is found in a wide range of rivers on the Caspian coast of Iran, in the Anzali Mordab, the southeast Caspian Sea, the southwest Caspian Sea and south-central Caspian Sea (Derzhavin, 1934; Holčík and Oláh, 1992; Abbasi et al., 1999; Kiabi et al., 1999).

Zoogeography

The genus Proterorhinus diverged from the related genus Neogobius about 5.2MYA during the late Miocene/early Pliocene according to mitochondrial DNA evidence (Dillon and Stepien, 2001).

Habitat

This species occurs in both salt and brackish waters and enters the fresh water of rivers. There are some permanent freshwater populations in Europe. The usual habitat is shallow sea bays, offshore banks or flowing water of streams but it may also be found in ponds and canals overgrown with vegetation. Where current is strong it hides under boulders. Some fish are found below 3 m depths in the sea. It is often found under stones or among weed, to which it can retreat rapidly if disturbed. Most activity takes place at night.

Age and growth

Life span is variably reported as 2 or about 5 years with maturity attained at 1-3 years. Young-of-the-year can mature by autumn at 5.5 cm in the Caspian Sea (Miller in Miller, 2004).

Food

Kuliev (1989) records insect remains, gammarids, daphnia, chironomids, molluscs and fish eggs in the guts of this species in Kirova Bay of Azerbaijan. For the Caspian Sea as a whole, amphipods predominate at 45.7% followed by mysids at 21.8%, cumaceans at 16.4% and decapods at 7.2%. Molluscs make up 5.6% (Kosarev and Yablonskaya, 1994). Iranian specimens contained crustacean and insect remains. Elsewhere polychaete worms and small fish have been found in stomachs of this species (Miller in Miller, 2004).

Reproduction

Both sexes produce sounds during the breeding season. Eggs are laid from shallow water (0.5 m) down to 20 m in bowl-shaped nests, under rocks, in empty mollusc shells, and on roots and stems of plants. Empty cans may be used. Two females may lay eggs in the same nest. Spawning begins in mid-April in the southern Caspian and may continue as late as the first half of August. Some fish may be mature in the middle of March in Iranian waters. Fish presumed to be young-of-the-year at 9.8 mm standard length have been collected on 26 April, by 10-11 June fish are 11.2-11.6 mm (mean 11.4 mm), on 20 June the 5 smallest fish of a sample were 12.5-14.1 mm, mean 13.6 mm while the 5 largest were 21.0-25.2 mm, mean 23.4 mm, and on 12 October the 5 smallest were 16.6-19.9 mm, mean 17.7 mm while the 5 largest were 26.4-33.3 mm, mean 29.6 mm. By 15 March, eggs in a 49.7 mm standard length fish are 1.3 mm in diameter and well-developed. This data suggests an extended spawning season in Iran. However young are first found in mid-June according to Ragimov (1987). Eggs are deposited in 2-3 batches and are guarded. Females contain up to 1335 eggs of diameter 3.3-3.6 by 1.4-1.5 mm. Elsewhere up to 2500 eggs may be laid. Egg clutches can be transported on the hulls of ships (Ahnelt et al., 1998). Males are nest guarders.

Parasites and predators

Unknown for Iran.

Economic importance

Robins et al. (1991) list this species as important to North Americans. Importance is based on its use in aquaria and because it has been introduced outside its natural range (Jude, 2001).

Conservation

Lelek (1987) classifies this species as vulnerable in Europe on account of water level changes. Kiabi et al. (1999) consider this species to be data deficient in the south Caspian Sea basin according to IUCN criteria. Criteria include few in numbers, medium range (25-75% of water bodies), absent in other water bodies in Iran, and present outside the Caspian Sea basin.

Further work

The biology of this species in Iran is not well known.

Sources

Type material: See above for Gobius nasalis (ZMB 5015).

Iranian material: CMNFI 1970-0530, 66, 41.6-64.5 mm standard length, Gilan, Nahang Roga River (37º28'N, 49º28'E); CMNFI 1970-0542, 5, 48.0-59.6 mm standard length, Gilan, Old Safid River estuary (37º23'N, 50º11'E); CMNFI 1970-0585, 2, 52.6-55.9 mm standard length, Gilan, Nahang Roga River (37º28'N, 49º28'E); CMNFI 1970-0590, 5, 39.5-47.7 mm standard length, Mazandaran, Shesh Deh River near Babol Sar (no other locality data); CMNFI 1979-0787, 3, 52.7-59.1 mm standard length, Gilan, Nahang Roga River (37º28'N, 49º28'E).

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