New geographical record of the lined rockskipper , Istiblennius lineatus ( Valenciennes , 1836 ) from the Iranian coast of the Makran Sea ( Teleostei , Blenniidae )

The lined rockskipper, Istiblennius lineatus, is a species of combtooth blenny fish distributed from the Laccadive and Maldive islands, central Indian Ocean, east to Mangareva and Gambier Islands in the Pacific Ocean. It occurs as far north as Toyohama, Japan, and now it is recorded from the coastal area of the Makran Sea, Iran. Six specimens of I. lineatus were collected from 3 localities in the Iranian coast of the Makran Sea during a fish survey in November 2015. These specimens represent the first record of the species from Iranian waters as well as an extension of its known geographical range within the Indian Ocean. The morphological features of these specimens are herein described and discussed.


Introduction
The family Blenniidae (combtooth blennies) comprises 58 genera and 397 species (Nelson et al. 2016) of small benthic fishes.They are distributed worldwide, with most species occurring in shallow, coastal, tropical and temperate marine waters, along with a few species known from fresh and/or brackish water where they occur in a variety of habitats: rocky intertidal, coral reefs, mangroves, oyster beds, and in the lower reaches of most rivers (see Patzner et al. 2009, Lin andHastings 2013).Combtooth blennies share several unique features including incisiform teeth in a single comb-like row on the dentaries and premaxil-laries.While the family is easily distinguished from other blennies, the classification within the Blenniidae has a long and complicated history (Lin and Hastings 2013).
The genus Istiblennius Whitley, 1943, in the tribe Salariini, comprises 14 valid species (Froese and Pauly 2017) that extend over the entire tropical Indo-west and central Pacific (Springer and Williams 1994) including the Persian Gulf and Makran Sea.To date, 3 species of the genus Istiblennius have been reported from the Persian Gulf and Makran Sea (Gulf of Oman): I. edentulus (Forster and Schneider, 1801), I. pox Springer andWilliams, 1994, andI. spilotus Springer andWilliams, 1994.We herein report the first record of occurrence of I.  1) were taken to the nearest 0.1 mm using digital calipers.A stereomicroscope was used for the meristic characters.Morphometric characters were expressed as a percentage of standard length (SL) or a percentage of head length (HL) as appropriate.Morphometric methods followed Alp and Kara (2007); meristic methods followed Springer and Williams (1994).

Results
We primarily used the key of Springer and Williams (1994) for the identification of the species of the genus Istiblennius and subsequently identified the collected individuals as I. lineatus (Figs 2,3,5,6) by analyzing the following morphological characters: Dorsal rays XIII, 21-22; anal rays II, 22-23; pectoral rays 14; pelvic rays I, 3; teeth in jaws numerous and incisiform; no canine tooth posteriorly on lower jaw; edge of upper lip crenulate, of lower lip smooth; supraorbital tentacle branched; no cirri on nape; males have a bladelike uniformly pigmented fleshy crest on head (Fig. 5); females lack crest; dorsal fin deeply incised before soft  Istiblennius lineatus is distinguished from its close relative, I. pox (Fig. 4) by more or less uniformly dusky or banded crest on head of males (vs spotted crest on head of males).Istiblennius lineatus is distinguished from I. spilotus by margin of upper lip crenulated (vs.margins of both lips crenulated).Istiblennius lineatus is distinguished from I. edentulus by margin of upper lip crenulated (vs margins of both lips smooth).
Istiblennius lineatus is distributed from the Laccadive (Jones and Kumaran 1980) and Maldive islands, central Indian Ocean, east to Mangareva, Gambier Islands, Pacific Ocean.It occurs as far north as Toyohama, Japan.
It is now recorded from the coastal area of the Makran Sea, Iran (Figs 7, 8).

Discussion
The lined rockskipper, I. lineatus, has a wide distribution range and it is found in the Indo-Pacific and Western Central Pacific oceans (Kami 1971).They inhabit the intertidal zone of rocky shores and rocky reef flats (Lieske and Myers 1994), and are found in the rock pools, har-

Figure 1 .
Figure 1.Sampling sites of Istiblennius lineatus (red circles) from the Iranian coast of the Makran Sea.
bors, and mangrove zones(Kuiter and Tonozuka 2001), where they graze on algae present on the rocks.The present record represents a new addition to the marine fish species list for Iran, showing high biodiversity for the region.The record of the lined rockskipper in Iranian waters indicates that a suitable habitat for this species occurs along the Iranian coast of the Makran Sea.

Figure 8 .
Figure 8. World distribution map of Istiblennius lineatus including new record in the coastal sides of the Makran Sea (red circles) and previous records (black circles).
lineatus(Valenciennes, 1836)from the Iranian coast of Persian Gulf and Makran Sea and provide a morphological description of the specimens supporting such record.

Table 1 .
Morphometric characters of 5 specimens of I. lineatus collected from the Iranian coast of the Makran Sea.TL and SL in mm.