Genus Benthophilus
Eichwald, 1831

Recheck Benthophilus illustrations in this account for source (correct species)

The tadpole gobies are found in the Black and Caspian seas where there are about 20 species, 16 endemic to the Caspian (Pinchuk and Miller in Miller, 2004; Boldyrev and Bogutskaya, 2007). The general Farsi name for fishes in this genus is گاو ماهي (gav mahi) or سگ ماهي (sag mahi), not repeated under each species description.

Members of this genus are characterised by the broad and flattened head, dorsal muscles not extending to the eyes, no sensory canals or pores, first dorsal fin with 2-4 rays, well-separated form the second dorsal fin, the caudal fin has only 2 rows of papillae, head and body scaleless but with spinulose bony granules, scutes and platelets except in adult males which are naked (and cannot therefore be readily identified), anterior nostrils developed as small tubes overlying the upper lip, no swimbladder, a longitudinal dermal fold usually present on each side behind the mouth corner, and presence of a chin barbel. There is no pelagic larval stage and eggs are large and oligoplasmatic. Ahnelt (2003) discuss the unique specialisations in the postcranial skeleton of benthophiline gobies (which also includes Anatirostrum and Benthophiloides) including reductions in vertebral numbers and arrangement of pterygiophores. Pinchuk and Miller in Miller (2004) review other characters that show relationships of this specialised group within a larger tadpole-goby clade, the broad and flattened head being the most obvious.

Pinchuk and Miller in Miller (2004) give details of the head neuromast organs that characterise this genus, namely 6 transverse infraorbital rows, 1-4 before and 5s and 6s well above the level of the hyomandibular row b; row a is absent; row 5s is distant from row 4 which does not extend above the level of row b; rows 5i and 6i are arranged successively but row 5i is mostly below the level of row 6i separating the latter from the posterior end of row d; dorsal supraorbital rows o very short and well-separated in the dorsal midline; and supraorbital series p present in interorbit as 3 pairs of short transverse rows.

These fishes are found in brackish waters with a salinity up to about 20‰, in deeper waters, estuaries and coastal waters. Life span of these tadpole gobies is only a year, some individuals maturing at 6-7 months, called ephemery. Fish die after spawning, females earlier than males by 3-4 weeks (Boldyrev and Bogutskaya, 2004; 2007).

Pinchuk and Miller in Miller (2004) and Boldyrev and Bogutskaya (2004; 2007) give descriptions and keys for all Caspian Sea species. The 5 species cited here are the ones with records from Iran although it is likely other species will eventually be found along the southern Caspian Sea coast. Boldyrev and Bogutskaya (2007) gives keys and descriptions to all the species.

Benthophilus abdurahmanovi
Ragimov, 1978

Endemic to the Caspian Sea and found in the North Caspian. No Iranian record.

Benthophilus baeri
Kessler, 1877

Common names

gavmahi-ye Baer, gavmahi-ye tokmehsar.

[Ber comcaxulu in Azerbaijan; Baer pugolovka or Baer tadpole goby in Russian].

Systematics

Benthophilus Baeri was described from the Caspian Sea at Mangyshlak Peninsula, Kazakhstan and in the South Caspian.

A specimen listed as a syntype is in the Natural History Museum, London under BM(NH) 1897.7.5:16 (32.5 mm standard length) from St. Petersburg University (sic, ZISP?) with others in the Zoological Institute, St. Petersburg (ZISP 2239, lectotype and ZISP 53665 (ex 2239) (4)) and SPU 395 (463/410) (1) (Eschmeyer et al., 1996; Pinchuk et al., 2004).

Lectotype: ZISP 2239. Paralectotypes: (11) BMNH 1897.7.5.16 [ex St. Petersberg Univ.] (1), SPU 395 [463/410] (1), ZIN 53665 [ex 2239] (4).

Key characters

This species has very large and high, conical tubercles arranged in rows, not all tubercles are spinous, dorsal row tubercles usually 11-17 (lower than other Benthophilus), ventral row tubercles 9-14 (lower than other Benthophilus), granules are mostly absent between body tubercles rows, interorbit with a shallow median groove, a chin barbel is present, there are 1-2 dermal barbels behind jaw angle, the first dorsal fin has 1-2 spines, and dark bands are absent.

Morphology

First dorsal fin with 0-2 spines, usually 1 (Ragimov (1985) and Boldyrev and Bogutskaya (2007) but 2 according to Pinchuk et al. in Miller (2004)), second dorsal fin with 1 spine followed by 6-9, usually 7, soft rays. Anal fin with 1 spine followed by 5-9, usually 6-7, soft rays. Dorsal row tubercles 11-17, usually 13-15, lateral row 1-12, usually 7-9 (but sometimes completely absent), and abdominal row 9-14, usually 11-12. Total vertebrae 24-27. Tubercles on the head and flanks are large and can bear 1-4 sharp spines but only some tubercles retain spines. The dorsal tubercle row continues onto the head ending near the eyes while the lateral row is short, extending from a level between the dorsal fins and ending at the rear of the second dorsal fin. There may be a few small granules scattered between the major row tubercles and on the head. There is a long chin barbel, about equal to eye diameter. There is one neuromast in row 7 behind the eye.

A single Iranian specimen had ?

Sexual dimorphism

The second dorsal and anal fins of large males are enlarged.

Colour

The back, upper flank and upper head are pale grey to pale brown with dark grey speckles, and often minute dark dots form dark areas. Some bands may be weakly expressed on the back and flank, more obvious in immature specimens. The lower body and belly are whitish. The pectoral, second dorsal and caudal fins have dark grey speckles and bars while the other fins are pale.

Size

Reaches 8.6 cm for males and 6.9 cm for females.

Distribution

Found in the central and southern Caspian Sea, rarely in the northwest Caspian. Reported from Gorgan Bay, the southeast Caspian Sea, southwest Caspian Sea and south-central Caspian Sea in Iran (Kiabi et al., 1999; map in Reshetnikov, 2002; Pinchuk et al. in Miller, 2004).

Zoogeography

A Caspian Sea endemic, part of a unique fauna poorly studied and collected in Iranian waters, as are all its relatives below.

Habitat

Found in depths of 5 to 81 m in littoral areas and also known to enter rivers in Russia (Reshetnikov et al., 1997). Found at 0.5-30.0 m in warm seasons and migrates to deeper water at 100 m in winter (Boldyrev and Bogutskaya ,2007). During the spawning season they are absent from shallow waters (5-10 m) and deeper waters (30-50 m)(Pinchuk et al. in Miller, 2004).

Age and growth

Up to 4 age groups are known (Reshetnikov, 2002) although Pinchuk et al. in Miller (2004) indicate life-span may be only 18 months.

Food

Corophiid crustaceans and some molluscs such as gastropods are principal diet items. Cumaceans, amphipods and Nereis worms are also important food items (Pinchuk et al. in Miller, 2004).

Reproduction

Mature males measure 8 cm while a mature female from the same collection was 6 cm (Berg, 1948-1949) while Pinchuk et al. in Miller (2004) state that both sexes are mature by 4.0 cm, in the first year of life. Eggs have a maximum diameter of 1.2-1.8 mm and a minimum diameter of 0.3-0.5 mm and fish up to 5.2 cm long produce up to 1860 eggs (Reshetnikov, 2002). Spawning takes place from the second half of May to August and rarely into September with a second batch of eggs laid in July (Pinchuk et al. in Miller, 2004). Eggs are laid on silt and silt-sand bottoms, probably using shells, at 10-25 m (Pinchuk et al. in Miller, 2004).

Parasites and predators

None recorded from Iran.

Economic importance

This species is food for sturgeon and Sander species (Pinchuk et al. in Miller, 2004).

Conservation

Kiabi et al. (1999) consider this species to be data deficient in the south Caspian Sea basin according to IUCN criteria. Criteria include possibly few in numbers, limited range (less than 25% of water bodies), absent in other water bodies in Iran, and absent outside the Caspian Sea basin.

Further work

The biology and distribution of this species in Iranian waters needs to be studied.

Sources

Type material: See above (BM(NH) 1897.7.5:16).

Iranian material:

Benthophilus casachicus
Ragimov, 1978

Endemic to the Caspian Sea and found on the eastern Caspian coast and the Volga delta area. No Iranian record.

Benthophilus ctenolepidus
Kessler, 1877

Common names

gavmahi-ye shafaf or shaffaf (= transparent or clear goby); gavmahi-ye Lankaran or gavmahi-ye Lenkoran.

[prozrachnaya pugolovka or transparent tadpole goby, shipogolovaya pugolovka or spiny-headed (?) tadpole goby in Russian; spiny-scaled tadpole goby; Lenkoranskaya pugolovka or Lenkoran tadpole goby in Russian for the subspecies in the southern Caspian Sea].

Systematics

A subspecies reported from off the Iranian coast was Benthophilus ctenolepidus pinchuki Ragimov, 1982 but this is now recognised as a distinct species by Pinchuk and Miller in Miller (2004) (see below). The lectotype of Benthophilus ctenolepidus as designated by Ragimov (1982) is in the Zoological Institute, St. Petersburg under ZISP 10897 with 3 paralectotypes lost and 1 paralectotype from ZISP in the Natural History Museum, London under BM(NH) 1897.7.5:13 (66.9 mm standard length) (Eschmeyer et al., 1996). The type locality is "yuzhnoi i srednei chastyakh' Kaspiiskago morya" (= southern and middle Caspian Sea), or Caspian Sea, 40°08'N, 0°26'E off Baku, Azerbaijan (in Eschmeyer's "Catalog of Fishes" online, downloaded 22 August 2007). Records of B. magistri Iljin, 1927 in the Caspian Sea, as B. m. lencoranicus Ragimov, 1982, are this species (Boldyrev and Bogutskaya, 2007). The taxon Benthophilus magistri lencoranicus Ragimov, 1982 was described from "raione protib Zelenogo bugra (38°10' s. sh.)" (= area opposite Green Hill, Turkmenistan). The holotype of lencoranicus is in the Caspian Biological Station, Institute of Zoology, Azerbaijan under CBSIZA 546 (no. 2), paratypes under 546 (20) and additional non-type material in the Zoological Institute, St. Petersburg under ZISP 23131 and 41912 (9) (Eschmeyer et al., 1996). Boldyrev and Bogutskaya (2007) were unable to locate IZA 546.

Key characters

The narrow head has a trough-shaped depression or groove on the occiput, the large tubercles are vertically elongate, curved and crest-like and have their rear edges fringed with a comb of spines, dorsal row tubercles usually 30-33, abdominal row tubercles usually 24-26, temporal and occipital region without large tubercles but having granules, the body has tiny granules anteriorly interspersed among the large tubercles, dermal filaments present or absent, a small but well-developed chin barbel is present, the dermal process behind jaw angle is lobed, narrow, with an acute protuberance, first dorsal fin spines 3-4 (rarely 2), and back without brown bands.

Morphology

First dorsal fin with 3-4 spines, second dorsal fin with 1 spine followed by 8-11, usually 9-10, soft rays. Anal fin with 1 spine followed by 7-11, usually 8, soft rays. Total vertebrae 29-230. Dorsal row tubercles 27-33, usually 30-33 (?) or 22-24 (Boldyrev and Bogutskaya, 2007), lateral row 11-22, usually 17-19, abdominal 20-26, usually 24-26 (22-24 in Boldyrev and Bogutskaya (2007)). Tubercles on the head (when present) and flanks are large and bear sharp spines, the flank tubercles being angular in shape. The dorsal row of tubercles is incomplete, usually beginning below the first dorsal fin. The first 3-4, and as many as 7, dorsal row tubercles are markedly smaller than the succeeding ones. The dermal plate or fold behind the mouth corner is large (1.2 times eye diameter), oval, and without a wavy margin.

Sexual dimorphism

Undocumented.

Colour

Mostly transparent as the name suggests, a light to ash grey. The body bears dark lines and speckles but no strong dark bands, spots or blotches. The belly is yellowish-white. The dorsal and pectoral fins have thin banding and the pelvic and and anal fins are pale.

Size

Reaches 10.7 cm.

Distribution

Found in the central, southwestern and southeastern Caspian Sea and in adjacent Iranian waters (Ragimov, 1965). Records are from Astara on the Azerbaijan-Iran border to Hasan Kuli in Turkmenistan and adjacent waters.

Zoogeography

A Caspian Sea endemic.

Habitat

Found in depths of 0.5-74 m in littoral areas but deeper than B. magistri and B. macrocephalus. It feeds and spawns in 0.5-10.0 m and migrates to deeper water in winter. Occurs in higher salinity areas at 12.4-13.0‰. Jolodar and Abdoli (2004) place it at 30-200 m depths in the south Caspian Sea basin. The pelvic fin is less developed, shorter and not as dilated than in these shallow water species.

Age and growth

Life span is probably not more than 18 months with maturity at one year (Pinchuk and Miller in Miller, 2004).

Food

Food in northern Caspian specimens was found to include mostly corophiid amphipods, with some gammarids, other crustaceans, and gastropods (Pinchuk and Miller in Miller, 2004).

Reproduction

Spawning is thought to occur from spring to autumn and into winter (Pinchuk and Miller in Miller, 2004).

Parasites and predators

None reported from Iran.

Economic importance

None.

Conservation

Kiabi et al. (1999) consider this species to be data deficient in the south Caspian Sea basin according to IUCN criteria. Criteria include possibly few in numbers, limited range (less than 25% of water bodies), absent in other water bodies in Iran, and absent outside the Caspian Sea basin.

Further work

The biology and distribution of this species in Iranian waters needs to be studied.

Sources

Based on Pinchuk and Miller in Miller (2004).

Type material: See above under B. ctenolepidus (BM(NH) 1897.7.5:13).

Benthophilus granulosus
Kessler, 1877

Endemic to the Caspian Sea and found in coastal areas of the North and eastern and western Middle Caspian. No Iranian record although Kottelat and Freyhof (2007) map this species from the Iranian shore.

Benthophilus grimmi
Kessler, 1877

A Caspian Sea endemic found in the western part of the Middle Caspian and the northern part of the South Caspian south to about 39º40'N. No Iranian record.

Benthophilus kessleri
Berg, 1927

A Caspian Sea endemic found in coastal waters of the eastern Middle Caspian. No Iranian record.

Benthophilus leobergius
Berg, 1949

Common names

gavmahi-ye akhtari (= stellate or starry goby), gav mahi bacheh qurbaqei, gavmahi-ye bacheghoorbagheie, sebele.

[ulduzlu comcaxul or khazar julduzlu chomchakhulu in Azerbaijan; zvezdchataya pugolovka or stellate tadpole goby in Russian; Caspian starry goby, Caspian stellate goby].

Systematics

This taxon was originally described as a subspecies of Benthophilus stellatus (Sauvage, 1874). B. stellatus is now restricted to fish from the Black Sea. Note that views do conflict on the status of this taxon and more studies remain to be done (Pinchuk et al. in Miller, 2004).

The subspecies leobergius (sic; leobergi has been used, see below) was first proposed by Il'in (1949) and was thought not be available as no distinguishing features were given in the description (Eschmeyer et al., 1996) although Berg (1948-1949) gives a description referring to "higher development of spiny tubercles" and colouration "less bright" than then Black Sea form in his volume III dated 1949 (not 1948 as given in Eschmeyer et al. (1996)). Eschmeyer et al. (1996) consider that Berg may be the author of this taxon and Pinchuk et al. in Miller (2004) concur. The holotype is probably in the Zoological Institute, St. Petersburg under ZISP 10891 (Eschmeyer et al., 1996). Berg (1948-1949) notes that the taxon is found "in the freshened regions throughout the Caspian Sea, south to Astrabad Bay (No. 10891, 5 August 1874, 62 mm)". This may be the type locality, i.e. Gorgan (= Astrabad) Bay, Iran. However this specimen may be merely recording the southernmost distribution of the taxon and a larger fish at 103 mm under ZISP 23128 labeled as from the Caspian Sea could be the holotype as it is depicted in two views (Figure 858, p. 1115 in the Russian text and p. 196 in the English text, and Figure 859, p. 1116 Russian and p. 197 English). Both these fish may be syntypes. Il'in (1949) simply referred to "Kaspii", i.e. the Caspian Sea, as the type locality. Boldyrev and Bogutskaya (2007) selected ZISP 23128 as the lectotype.

Benthophilus macrocephalus variety b (large-scaled) Kessler, 1877 is a synonym of B. s. leobergius according to Berg (1948-1949). Benthophilus aculeatus Baer in Lukina, 1984 is possibly a synonym, with no types known (Boldyrev and Bogutskaya, 2007).

Kottelat (1997) considers, tentatively, that Benthophilus stellatus is restricted to the Black Sea basin. Furthermore, Kottelat points out that perhaps the Caspian Sea species is Benthophilus leobergi Ragimov, 1978, leobergi since the species is founded on a personal name and should be emended to this spelling and Ragimov, 1978 since the name is a nomen nudum in Iljin (1949) (no description or diagnostic characters (but see above)) until Ragimov (1978) makes the name available by listing characters distinguishing it from B. s. casachicus. Benthophilus casachicus Ragimov, 1978 is then another Caspian Sea species.

Key characters

Distinguished by stellate tubercles, mostly spinous at the tip, tubercles rows on body well-defined but scattered on head, dorsal tubercles 25-30, abdominal tubercles 21-25, granules present predorsally but mostly absent from head and body, interorbit without a median groove, chin barbel present but small (eye diameter or less), dermal process behind jaw angle obvious, 3-4 first dorsal fin spines, and first dorsal fin patterned. and dark bands present.

Morphology

The snout is very long, 30-33% of head length, and the upper jaw projects. The head is wider than long. There are 3-4 neuromasts in row 7 (also in B. macrocephalus, usually 1 in other species). First dorsal fin spines 2-6, usually 3-4, second dorsal fin with 1 spine and 6-11 soft rays, usually 8-10, anal fin with 1 spine and 7-9 soft rays. Pectoral fin rays 15-18. The gill arch is without evident rakers and is irregularly tuberculate. Vertebrae number 28-31. There are 10-11, often 11, precaudal vertebrae (commonly 9 in other Benthophilus). There is a flap behind the jaw angle. The gut is moderately long with several convolutions. The body bears 3 rows of very spinulose tubercles; the upper row numbering 25-30, usually 26-28 or 27-29 (authors vary), the lower 21-25, usually 23-25 or 22-24 (authors vary), and the dorso-lateral row 15-24, usually 18-20. The ventro-lateral row is usually absent.There are numerous small tubercles between the main rows on the flanks, particularly the dorsal and lateral rows. The head surface has numerous small and large tubercles, arranged irregularly. Small tubercles or granules are even found on the medial half of the eyeball. There are 2 well-developed tubercles on the midline between the eyes (in 80% of specimens) as opposed to one or none in other Benthophilus.

The chromosome number of B. leobergi is 2n=44 with 46-48 chromosomal arms (Grigoryan and Vasil'ev, 1993; Vasil'yev and Grigoryan, 1993) or 2n=46 (Klinkhardt et al., 1995).

Iranian specimens had the following meristics: first dorsal fin spines 3(1) or 5(1), second dorsal fin with 1 spine and 9 soft rays (2), anal fin with 1 spine and 8 soft rays (2), and pectoral fin with 17(2) branched rays. The extent of tubercle rows is difficult to distinguish since their size gradually decreases posteriorly and their arrangement is irregular anteriorly. Dorsal row tubercles 31(2), lateral row tubercles ca. 19(2), and lower row tubercles 23(1) or 24(1).

Sexual dimorphism

The pectoral fin is longer than the pelvic fins in males when spawning. Females have a very small chin barbel.

Colour

Overall colour is brownish to whitish-grey. The head surface and upper flank have large, dark brown spots and small dark speckles. The body has about 5 transverse bands which circle the first dorsal fin, rear of the second dorsal fin and caudal fin base when viewed from above. Rows of speckles are found on the second dorsal, pectoral and caudal fins.

Size

Reaches 10.7 cm.

Distribution

Found in the Caspian Sea. In Iran, it is reported from Gorgan Bay (Abdoli, 1994a). the Safid River (Abbasi et al., 1999), the southeast Caspian Sea, southwest Caspian Sea and south-central Caspian Sea (Kiabi et al., 1999). Jolodar and Abdoli (2004) consider it to be widely distributed along the Iranian coast but more abundant in Gomishan Wetland and Gorgan Bay. It is also recorded between Kultuk and Astara in Azerbaijan, near the Iranian border (Ragimov, 1965).

Zoogeography

Endemic to the Caspian Sea.

Habitat

This species is found in the Caspian Sea and in brackish and fresh waters, and is widespread in coastal waters over sand and shell debris bottoms down to at least 100 m. Said to prefer salinities below 9‰. Feeding and spawning occur in shallow water at 0.5-10.0 m, retreating to deeper water in winter (Boldyrev and Bogutskaya, 2007). It is said not to enter fresh waters unlike its relative B. stellatus but is known from fresh water in the Volga delta. In spring and autumn it can be found in coastal zone at 1-20 m. It prefers warmer waters at 18-26ºC (Caspian Sea Biodiversity Database, www.caspianenvironment.org). e

Age and growth

Young fish reach 1.83 cm in January and early February after spawning in autumn and reach their maximum size in July-August of the following year at 8.5-9.4 cm and 21.6-24.7 g. The spring spawners reach 1.9-2.0 cm and 0.17-0.24 g in May-June and 3.5-5.9 cm and 1.1-5.4 g in July-August. With two spawning seasons, there are always fish of markedly different size and maturation stage in any population. Life span is about 18 months (Ragimov, 1985a).

Food

Diet is dominated by molluscs (bivalves and gastropods) but includes crustaceans, worms, insect larvae and small fishes. An Iranian specimen contained the remains of a crab.

Reproduction

In the southern Caspian spawning occurs at depths of 30-35 m and in October-December and March-April (in the northern Caspian it is in shallow water (1-5 m) and during summer months). Batch spawning occurs and eggs number up to 2136 large and 1284 small with diameters 1.5-2.1 mm and 0.3-0.7 respectively (Ragimov, 1985a). Fecundity may reach 3500 eggs and maximum diameter 4.5 mm (Reshetnikov, 2002). Males protect the nests; unprotected nests have their eggs eaten by crustaceans within 2-3 hours (Caspian Sea Biodiversity Database, www.caspianenvironment.org).

Parasites and predators

None reported from Iran but this fish is eaten by other fishes and by seals.

Economic importance

None.

Conservation

Kiabi et al. (1999) consider this species to be of least concern in the south Caspian Sea basin according to IUCN criteria. Criteria include medium 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 and distribution of this species in Iranian waters needs to be studied.

Sources

Iranian material: CMNFI 1971-0326A, mm standard length, (): CMNFI 1970-0543, (); 3, 90.4-90.9 mm standard length, Mazandaran, Gorgan Bay and the Caspian Sea.

Benthophilus leptocephalus
Kessler, 1877

A Caspian Sea, deep-water endemic found in the western Middle Caspian south to 39º41'N and the eastern South Caspian south to Hasan Kuli in Turkmenistan. No Iranian record.

Benthophilus leptorhynchus
Kessler, 1877

A Caspian Sea, deep-water endemic known from the western coast of the Middle Caspian and the north of the South Caspian south to Baku. No Iranian record.

Benthophilus macrocephalus
(Pallas, 1788)

Common names

gavmahi-ye vazaghi (= tadpole goby).

[iribas comcaxul in Azerbaijan; Kaspiiskaya pugolovka or Caspian tadpole goby in Russian; bighead goby].

Systematics

Eschmeyer et al. (1996) gave the publication date as 1788 (later 1787), Berg (1948-1948) and Pinchuk and Miller in Miller (2004) as 1787. The original description is dated 15. Mars. 1787 but was probably published in the following year (not verified). The type locality is the Caspian Sea near the mouths of rivers and streams, and in small inlets, although the type of Gobius macrocephalus was probably from the Volga delta. No type specimens are known.

Key characters

Distinguished by having moderate, stellate tubercles, spinous at their apex with usually 22-23 (but see below) in the dorsal row and 19-24 in the abdominal row, numerous granules over the head and body, head wide, width less than to slightly more than length, large snout tubercle, two rows of tubercles from dorsal rows extend onto temporal and occipital areas, no occipital groove, chin barbel present, dermal process behind jaw angle very large (base length 20-26% head length), rounded or scalloped in larger fish, first dorsal fin spines 3-4, no dark annular bands.

Morphology

There are 3-4 neuromasts in row 7 (shared with B. leobergius, usually one in other Benthophilus). The head is very wide , 103-111% head length (only B. leobergius has similar measurements). First dorsal fin with 2-4 spines, usually 3, second dorsal fin with 1-2 spines, usually 1, followed by 6-10 soft rays, mostly 8-9. Anal fin with 1 spine followed by 6-9, usually 7, soft rays. There are no evident gill rakers on the arch but rounded tubercles are present. Total vertebrae number 27-28, with 17-19 caudal vertebrae, usually 18. The head and body are covered with minute granules with larger stellate scutes or tubercles bearing sharp spines on the body and on the dorsal and lateral head surfaces. Granules extend onto the medial half of the eyeball and onto the pectoral fin base. Scutes are few and scattered on top of the head, strongly developed and close together on the side of the head. There are three longitudinal rows of tubercles on the body with 19-27, usually 22-23 (or 23-27, modally 25, authors differ) tubercles in the dorsal row, 8-16, usually 10-13, laterally, and 19-24 abdominally, usually 21-22. The ventro-lateral row is usually absent. The belly is naked. The gut is moderately elongate with several convolutions.

Iranian specimens had the following meristics: first dorsal fin spines 3(3), second dorsal fin with 1 spine and 8 soft rays (4), anal fin with 1 spine and 7 soft rays (4), and pectoral fin with 16(1) or 17(3) branched rays. The extent of tubercle rows is difficult to distinguish since their size gradually decreases posteriorly and their arrangement is irregular anteriorly. Dorsal row tubercles 25(4), lateral row tubercles 9(1), 13(2) or 14(1), and lower row tubercles 21(1), 22(2) or 23(1).

Sexual dimorphism

Mature males lose the granules, scutes and tubercles, their dorsal and anal fins enlarge and their cheeks become more muscular or inflated.

Colour

Overall colour is ash-grey with scattered melanophores on the upper flank and dorsal surface. Melanophores line the pectoral and caudal fin rays being best developed on the more dorsal rays.

Size

Reaches 13 cm.

Distribution

This species is reported from the Caspian Sea including the south from the Anzali Mordab and Gorgan Bay in Iran and between Kultuk and Astara in Azerbaijan (Ragimov, 1965).

Zoogeography

A Caspian Sea endemic.

Habitat

Found mostly in the sea over muddy bottoms but may approach river mouths. Commonly at 0.5-10.0 m, migrating to deeper areas at 20-25 m in winter. De Filipii (1865) reports this species from the Murdab (= Anzali Mordab presumably) in relatively fresh water.

Age and growth

Young fish taken in early June are 2.4-3.5 cm and 0.35-1.00 g and by the end of November they are 7.0-8.0 cm and 10.15 g, the maximum values for the species. By February-March they are nearly mature (Ragimov, 1985a). There are up to 4 age groups (Reshetnikov, 2002) although Pinchuk et al. in Miller (2004) suggest 18 months.

Food

Food includes molluscs (80%) crustaceans, fish, worms and chironomids (Zenkevitch, 1963). Iranian fish contained clams, crustaceans and a polychaete in gut contents.

Reproduction

Spawning takes place in April-May and rarely up to mid-June near the shore on silt or silt-sand bottoms with a mixture of shells. The eggs are laid in large, empty mollusc shells. Egg laying occurs in two batches as females carry eggs of two sizes. Fecundity of the larger eggs is up to 3180 and the smaller 1403. Their diameters are 2.0-3.0 mm and 0.3-0.6 mm respectively. Young are caught in early June (Ragimov, 1985a). Males probably die after spawning. An Iranian fish, 77.9 mm standard length, caught on 13 March had minute but developing eggs.

Parasites and predators

None reported from Iran.

Economic importance

None.

Conservation

Numbers in Iranian waters and threats to this species need to be assessed.

Further work

The biology and distribution of this species in Iranian waters needs to be studied.

Sources

Iranian material: CMNFI 1970-0543, CMNFI 1970-0544, mmm standard length, (); CMNFI 4, 55.3-82.8 mm standard length, Gilan, Caspian Sea near Bandar Anzali ().

Benthophilus mahmudbejovi
Ragimov, 1976

Endemic to the Caspian Sea and found on the western coasts of the Middle and South Caspian and the Volga delta region. No Iranian record.

Benthophilus pinchuki
Ragimov, 1982

Common names

None.

[Pugolovka Pinchuka or Pinchuk's tadpole goby in Russian]

Systematics

Originally described as a subspecies of B. ctenolepidus, Pinchuk and Miller in Miller (2004) recognise it provisionally as a distinct species. This taxon was described from "raione Belogo bugra y vostochnogo poberezh'ya Yuzhnogo Kaspiya" (= area of the White Hill (? locality not ascertained further by me) near the eastern coast of the southern Caspian Sea). A specimen listed as a syntype is in the Natural History Museum, London (no number, noted in October 1982). The holotype of pinchuki is in the Caspian Biological Station, Institute of Zoology, Baku, Azerbaijan under CBSIZA 52 (later in ZISP 53569, ex IZA), paratypes are under CBSIZA 304 (24, later 8 fish and ZISP 53660 9ex IZA 304) (6)). Additional material is in the Zoological Institute, St. Petersburg under ZISP 33143 (6) and 44346 (1) (Eschmeyer et al., 1996; on-line version downloaded 22 August 2007).

Key characters

Tubercles are vertically elongated, curved and crest-like, with a spiny fringe on their rear edge, dorsal row tubercles complete and 30-33, ventral row tubercles 23-27, granules are absent postorbitally on the head and on the body, temporal and occipital region without large tubercles, head narrow, the interorbit has a shallow median groove, dermal filaments present or absent, chin barbel usually present, dermal process behind jaw angle narrow (less than eye diameter) and barbel-like, first dorsal fin spines 3-4, and colour without dark bands.

Morphology

The first dorsal fin has 3-4 spines, usually 4, the second dorsal fin 1 spine and 9-11 soft rays, and the anal fin 1 spine and 8-11 soft rays (Ragimov, 1982; note the holotype has a much lower count of anal fin rays than figure in table). Dorsal row tubercles 30-33, usually 31-32 (other species having 30 or less usually except B. ragimovi), ventral row tubercles 23-27, and dorso-lateral row tubercles 10-23. Total vertebrae 30-32 and caudal vertebrae 21-23 (26-31 and and 17-21 in most other Benthophilus). The pelvic fin extends to the anus or beyond. Chin barbel less than half eye diameter. One neuromast in row 7.

Sexual dimorphism

Males may have longer pectoral fins than females and grow larger than females.

Colour

Not described except for the absence of dark bands, blotches and spots. Probably an overall greyish.

Size

Reaches 8.9 cm in males.

Distribution

Found throughout the Caspian Sea.

Zoogeography

Endemic to the Caspian Sea.

Habitat

Known down to 282-294 m, usually 50-100 m but as shallow as 20 m, and a salinity of 12.4-13.2‰.

Age and growth

Life span is probably 18 months with maturity at 1 year.

Food

Unknown.

Reproduction

Spawning probably occurs in spring as fry have been caught in late April.

Parasites and predators

Unknown.

Economic importance

None.

Conservation

Numbers in Iranian waters and threats to this species need to be assessed. Boldyrev and Bogutskaya (2007) call it a rare deepwater species.

Further work

The biology and distribution of this species in Iranian waters needs to be studied.

Sources

No specimens examined, based on Pinchuk and Miller in Miller (2004).

Benthophilus ragimovi
Boldyrev and Bogutskaya, 2004

Endemic to the Caspian Sea from the western coast of the Middle and South Caspian, south to Astara. No Iranian record.

Benthophilus spinosus
Kessler, 1877

Endemic to the Caspian Sea from the eastern and western coast of the Middle Caspian , the southeastern North Caspian and southeastern South Caspian. No Iranian record.

Benthophilus svetovidovi
Pinchuk and Ragimov, 1979

A Caspian Sea endemic found on the eastern coast of the Middle Caspian. No Iranian record.

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