Mesogobius nonultimus ( Iljin, 1936 )

Zarei, Fatah, Esmaeili, Hamid Reza, Abbasi, Keyvan, Kovačić, Marcelo, Schliewen, Ulrich K. & Stepien, Carol A., 2022, Gobies (Teleostei: Gobiidae) of the oldest and deepest Caspian Sea sub-basin: an evidence-based annotated checklist and a key for species identification, Zootaxa 5190 (2), pp. 151-193 : 173-174

25. Mesogobius nonultimus ( Iljin, 1936) ( Fig. 20 ), Caspian Toad Goby

Gobius nonultimus Iljin, 1936: 337 , fig. p. 325; type locality: 24 miles southwest of Ulsky Bank, Caspian Sea, depth 24 m above a bottom depth of 54 m, Turkmenistan; types: the holotype of this species, an adult female of 107.5 + 19.5 mm appears to be lost.

Etymology: Iljin (1936) did not provide an explanation of the specific name.

Distribution and habitat: Widely distributed in the open sea in all three areas of the Caspian Sea.A relatively deepwater mesohaline species ( Pinchuk & Miller 2004d).

Remarks: Kessler (1877) described Gobius nigronotatus from a single specimen, taken on the border between the North and Middle Caspian Sea areas at Fort Aleksandrovskiy, near Mangyshlak ( Kazakhstan) at 43 m, and the brief definition of this species provided by Berg (1949) corresponded in a number of characters with M. nonultimus (Iljin) , but differed chiefly in the alleged absence of head scales in the former and in the presence of six rather than seven first dorsal rays. However, D.B. Ragimov found just six first dorsal rays in material identified as M. nonultimus and small head scales that may be easily overlooked, as likely was the case before contemporary binocular microscopes and staining techniques. Pinchuk & Miller (2004d) tentatively synonymized those two nominal species. However, in the case that both species truly are conspecific, then M. nigronotatus ( Kessler, 1877) would become the senior synonym for the taxon. A detailed morphological and molecular analysis of samples from the three Caspian Sea areas is warranted.

Material examined: ZM-CBSU S036, 1, off Anzali , Gilan Province, Iran .

IUCN: DD ( Larson 2019b).

Figures

FIGURE 20. Mesogobius nonultimus. ZM-CBSU S036-1, 126 mm SL, off Anzali, Gilan Province, Iran.