A new marine gobiid species of the genus Clariger Jordan & Snyder (Gobiidae, Teleostei) from Taiwan

Abstract A new species of Clariger Jordan & Snyder, 1901 was collected from northern Taiwan. The genus was previously known only from Japanese waters. This discovery is the first formal and southernmost record of these marine gobies from the waters of subtropical Taiwan. The new species, Clariger taiwanensis sp. n., is distinguished from its congeners by a unique combination of features: (1) fin rays: dorsal-fin rays III, I/8; anal-fin rays modally I/8; and pectoral-fin rays modally 19 (2+16+1); (2) longitudinal dermal ridge on head with 6 barbels; and (3) specific coloration pattern: head and trunk dark brown with scattered pale spots and blotches; cheek, ventral portion of head sometimes pale with deep brown spots; pectoral-fin base with a dark brown band; and caudal fin mostly dark brown proximally and with alternating and irregular dark brown and pale bands distally. A diagnostic key to all nominal species from Japan and Taiwan is provided.


Introduction
The generally small body-sized gobiid fishes of the family Gobiidae constitute the most diverse group of marine teleost fishes (Miller 1988;Chen and Kottelat 2005). Within the family, the Luciogobius generic complex includes three related genera: Luciogobius Gill (1859), Astrabe Jordan and Snyder (1901) and Clariger Jordan and Snyder (1901), which share the following features (Akihito et al. 2000;2002): slender to elongate body with 30 or more vertebrae in most species, a longitudinal infraorbital papillae pattern, and first dorsal fin with fewer than 4 spinous rays or first dorsal fin absent. These gobies mainly inhabit coastal waters of Japan (Akihito et al. 2000;2002), but their ranges also extend toward Korea, eastern China, and Taiwan (Chen and Fang 1999;Akihito et al. 2000;2002;Wu et al. 2009). Yamada et al. (2009) investigated the molecular phylogenetics of the Luciogobius generic complex based on the Japanese species and revealed the very close relationship of these three gobiid genera.
Recently, collections of marine gobiid fishes have been made by the National Taiwan Ocean University (NTOU) team in the coastal region of northern Taiwan. An unusual dark goby species taken in one of these surveys appears to be an undescribed species and the first appearance of the Japanese endemic genus Clariger in Taiwan. The aim of this paper is to document the first record of Clariger from Taiwan and to describe this endemic species as new to science. A diagnostic key to all 6 nominal species of Clariger including the undescribed Japanese congener from Japan and Taiwan is also provided.

Materials and methods
All type specimens of the new species were collected by hand-net. All counts and measurements were made from specimens stored in 70% ethanol after 10% formalin preservation. Morphometric methods are from Miller (1988), and meristic methods follow Akihito et al. (1984). Terminology of cephalic sensory canals and free neuromast organ (sensory papillae) is from Wongrat and Miller (1991), based on Sanzo (1911). Type specimens are deposited in the collections of National Taiwan Ocean University (NTOUP), Keelung; and National Museum of Marine Science and Technology (NMMST), Keelung.
Abbreviations: A, anal fin; C, caudal fin; D1 and D2, first and second dorsal fins, respectively; P, pectoral fin; V, pelvic fin; and VC, vertebral count. All fish lengths are standard length (SL). Diagnosis. Clariger taiwanensis can be distinguished from other congeners by the following unique combination of features: (1) fin rays: dorsal-fin rays III, I/8; anal-fin rays modally I/8; and pectoral-fin rays modally 19 (2 free +16+1 free); (2) head with longitudinal dermal ridge including 6 barbels; and (3) specific coloration pattern when alive: head and trunk dark brown with scattered pale spots and blotches; cheek, ventral portion of head sometimes pale with deep brown spots; pectoral-fin base with a dark brown band; and caudal fin mostly dark brown proximally and with alternating and irregular dark brown and pale bands distally.
Description. Body rather slender, cylindrical anteriorly and laterally compressed posteriorly (all morphometric data are shown in Table 1). Head flat and depressed. Eye small. Interorbital region wide, bony interorbital width more than twice diameter of eye. Horizontal, infraorbital dermal ridge on upper part of cheek with 6 barbels (Fig. 1).
Snout flat and rather short. A pair of distinct longitudinal dermal folds beside nasal tubes on snout. Anterior nasal opening in forward-facing short tube, and posterior nasal opening round, flat. Mouth rather large, maxilla extending to vertical through rear margin of orbit. Teeth minute, jaws with 3-5 rows of conical teeth, teeth in outer rows largest in both jaws. Tongue margin bilobed anteriorly. Gill opening somewhat restricted, extending only slightly below lower margin of pectoral-fin base. Anus located anterior to vertical through origin of second dorsal fin. VC 14 + 18 = 32 (9 specimens). Trunk and head entirely naked.
Head lateral-line system: Head canals: head lacking sensory canals and head pores (as for genus). Sensory papillae: all infraorbital sensory papillae arranged in longitu-dinal pattern. Row a long and extending forward to below nostrils. Row b extending from anterior region of dermal ridge to posterior region of cheek. Row c long, running below the dermal ridge. Single cp located near row c. Row d located just above upper lip, row d1 well separated from row d. Rows ot and oi well separated. Row p surrounding orbit in interorbital region.
Colouration in fresh and preserved specimens: Head and trunk mostly dark brown with scattered pale spots and blotches when alive. Some individuals with larger pale spots in ventral half of trunk. Cheek, ventral portion of head, and underside of anterior portion of trunk sometimes pale with deep brown spots. First dorsal fin translucent with brown dotted spinous rays. Pectoral and second dorsal fins translucent with small deep brown spots. Pectoral-fin base with a dark brown band. Anal fin translucent with a few dark brown spots mostly on the branched rays. Caudal fin mostly dark brown proximally and with alternating and irregular dark brown and pale bands distally. Long preserved specimens with similar overall dark pattern as described above except disappearance of body pale spots.
Distribution. The new species has only been found from the coastal regions of Taipei County as well as Keelung City, Taiwan. It is highly likely that it represents an endemic marine gobiid species of Taiwan (Fig. 3).
Habitats. Clariger taiwanensis was found in tidal pools with gravel on the rocky substratum of northern coast of Taiwan. The habitat also supports other marine gobies, including several Bathygobius spp. (dominant), Eviota spp, Gobiopsis spp. and Priolepis semidoliata, as well as the Luciogobius spp.
Etymology. The specific name, taiwanensis, is in reference to the type locality from the coastal rocky shores of northern Taiwan. Remarks. Clariger taiwanensis shares a morphological similarity (infraorbital dermal ridge with several distinct cheek barbels) with the following four species: C. cosmurus, C. exilis, C. papillosus, and C. chionomaculatus. Cheek barbels are lacking in C. sirahamaensis. In addition to differences in cheek barbels, the new species can be separated from C. sirahamaensis by the pattern of pigmentation on the caudal-fin: fin dark brown proximally with dark brown and pale bands distally in C. taiwanensis vs. fin uniform grayish black with a pair of white spots on basal regions of both upper and lower lobes in C. sirhamaensis. Clariger taiwanensis can be separated from C. chionomaculatus by the number of free pectoral-fin rays (2 free rays dorsally vs. 1); and coloration (no large white marks on trunk vs. several large, round white marks on upper half of trunk). Clariger taiwanensis can be distinguished from the remaining three nominal species, C. cosmurus, C. exilis, and C. papillosus by the following features: (1) fin-rays counts: second dorsal-fin rays 8 vs. 10-13 in others; anal-fin rays 8 vs. 9-11; and (2) squamation: body entirely naked vs. body scaled at least on caudal peduncle.
So far as is known, C. taiwanensis is the only species of Clariger found outside Japan, now known from the subtropical island of Taiwan. It is very essential to survey more comprehensively the coastal waters of Taiwan as well as southern China to obtain a better understanding of the species diversity, distribution, and evolutionary history of Clariger and other members of the Luciogobius complex.
A diagnostic key to all nominal species of Clariger from Japan and Taiwan (adapted from Shiogaki 1988