Cryptocentrus shigensis Kuroda, 1956

Fujiwara, Kyoji, Psomadakis, Peter N., Swe, Thet Yu Yu & Motomura, Hiroyuki, 2022, First records of the two gobies, Cryptocentrus shigensis and Priolepis profunda (Actinopterygii: Gobiiformes: Gobiidae), from the Andaman Sea, Acta Ichthyologica et Piscatoria 52 (1), pp. 21-27 : 21

Cryptocentrus shigensis Kuroda, 1956

[English name: Shige shrimp goby] Fig. 1

Material examined.

SAIAB 208619, 41.1 mm SL, station 47 (14°41′27″N, 94°05′49″E), northeast of Coco Islands , Myanmar, Andaman Sea, Indian Ocean, 84 m depth, R/ V. Dr. Fridtjof Nansen (P. N. Psomadakis), bottom trawl, 2 Sep 2018 .

Description.

Counts and measurements are given in Table 1 and general appearance in Fig. 1 . Head and body slender, strongly compressed, width much less than depth. Anus located posteriorly, slightly separated from anal-fin origin. Snout short (much shorter than eye diameter), rounded; lateral profile steep, forming angle of ca. 60° with body axis. Eyes large, located dorsolaterally. Interorbital region very narrow (width much narrower than pupil diameter), flattened. Anterior and posterior nostrils close to each other; former located just before snout tip, with membranous tube; latter located posterodorsally of anterior nostril, small, circular. Mouth terminal, inclined anterodorsally, forming angle of ca. 50° with body axis. Lower jaw subequal to upper jaw, its posterior tip reaching vertical through posterior margin of pupil. Upper-jaw tip behind vertical through lower-jaw tip. Both jaws with irregular rows of small, pointed conical teeth, with tip of each slightly incurved posteriorly; teeth on outermost row on jaws spaced, distinctly larger than teeth on inner rows; 2 or 3 somewhat large canine-like teeth present on both sides of jaws; vomerine and palatine teeth absent. Gill membranes attached anteriorly to isthmus. Gill opening relatively narrow, anteroventral point extending slightly forward to vertical level of preopercle margin.

Cephalic sensory system. A detailed pattern of cephalic sensory system given in Fig. 1B . Head sensory canals pores well developed; anterior oculoscapular canal with pores B’, C (single), D (single), E, F, G, and H’; posterior oculoscapular canal with pores K’ and L’; preopercular canal with pores M’ and O’. Head sensory papillae damaged, but following conditions confirmed: 4 transverse papillae rows extending from lower eye margin to upper jaw (anterior 2 rows) and cheek (posterior 2 rows); 2 longitudinal papillae rows present on cheek; single transverse papillae row present between longitudinal papillae rows.

Scales. Body covered with deciduous (almost all scales lost due to abrasion) cycloid scales, small anteriorly, becoming larger posteriorly. Pre-dorsal- and pelvic-fin regions covered with small cycloid scales, anterior scaled margins reaching vertical through between eye and preopercle and just behind anteroventral point of gill opening, respectively; lower margin of pre-dorsal scaled area not reaching horizontal level of upper end of opercle. Entire head region (except for lateral surface of nape) naked.

Fins. All dorsal- and anal-fin spines slender, flexible. First dorsal fin triangular, all spines with very long filamentous tips, 2nd and 3rd spines longest (much longer than 1st dorsal-fin base) (Fig. 1C ); dorsal-fin origin posterior to vertical through pectoral-fin base. Second dorsal and anal fins relatively long, origin of latter slightly posterior to vertical through 2nd dorsal-fin origin, posteriormost rays of both fins well separated from caudal-fin base. Pectoral fin moderately long, pointed, middle rays longest, tips extending posteriorly to a vertical line drawn between dorsal fins. Pelvic fins fused medially with connecting membrane (between innermost rays) and well developed frenum (between spines); posterior tips located vertically level with pectoral-fin tip; pelvic-fin origin just below ventral end of pectoral-fin base; posterior margin of pelvic frenum smooth, slightly emarginated; all segmented pelvic-fin rays branched. Caudal fin very long (subequal to predorsal length), lanceolate.

Coloration.

Based on preserved specimen (Figs 1A , D , and E ). Head and body pale brown. Most pigmentation patterns lost, but three poorly defined brown blotches retained on right side of body, anteriormost blotch just behind opercle, middle blotch below 2nd dorsal-fin origin, posteriormost blotch on caudal-fin base (Fig. 1D ). Dorsal, anal and pelvic fins blackish-brown; pectoral and caudal fins light gray.

Identification.

Morphometric and meristic characters of the Andaman specimen (SAIAB 208619) agreed closely with the holotype of C. shigensis (Table 1 ) and the detailed description of the species provided by Akihito et al. (2013). In addition, the presently reported specimen conformed to other diagnostic characters for C. shigensis (e.g., pre-dorsal squamation and first dorsal- and caudal-fin shape; Figs 1A, C, and E ; see Remarks). Although head sensory papillae and body pigmentation patterns could not be completely determined due to damage, some characters [e.g., 4 transverse papillae rows extending from lower eye margin to upper jaw (anterior 2 rows) and cheek (posterior 2 rows) and position of three brown blotches on body; Figs 1B and D ] also matched those given by Akihito et al. (2013: 1591) and Kuroda (1956: fig. 1).

Distribution.

Cryptocentrus shigensis was originally described on the basis of a single specimen collected from Shizuoka Prefecture, Japan ( Kuroda 1956). Subsequently, Myers (1999) recorded the species from Palau [based on an unpublished photograph(s)], which remains the only record outside of southern Japan to date ( Akihito et al. 2013). Accordingly, the presently reported specimen, collected from the Andaman Sea, represents the first Indian Ocean record of the species.

Remarks.

Count of the longitudinal scale rows of the presently reported specimen (ca. 55) was much fewer than those given by the original description of C. shigensis (ca. 101; Kuroda 1956). However, re-examination of the holotype of the species revealed that its count was actually ca. 60 on the left side of the body (poor condition) and 58 on the right side (Table 1 ).

Currently, the generic position of C. shigensis is equivocal, the species being closer to Myersina Herre, 1934 rather than Cryptocentrus (the long filamentous tips on the 1st dorsal fin matching the former), according to Hoese and Lubbock (1982) and Winterbottom (2002). However, the pre-dorsal region covered with cycloid scales differs from the diagnosis of Myersina provided by Winterbottom (2002) (completely naked). In addition to the above-mentioned characters, C. shigensis can be easily recognized by the lanceolate caudal fin and four brown blotches on the body [3rd blotch (located under middle of 2nd dorsal fin; Kuroda 1956) of the presently reported specimen could not be determined] ( Kuroda 1956; Allen and Erdmann 2012; Akihito et al. 2013; this study).

Figures

Figure 1. Preserved specimen of Cryptocentrus shigensis (SAIAB 208619, 41.1 mm SL). (A, E) and (D), left and right sides of body, respectively; (B), close-up of head, showing cephalic sensory system; (C): close-up of 1 st dorsal fin (right side). Yellow dots and red circles indicate sensory papillae rows and brown blotches, respectively. AN and PN indicate anterior and posterior nostrils, respectively. Arrow head indicates anteroventral end of gill opening.