GOBIIDAE Bathygobius cyclopterus, 4.1 cm SL (photo by Ukkrit Satapoomin) Bathygobius cyclopterus (Valenciennes, 1837) Spotted Frill Goby D VI + I, 8-9; A I, 8; P1 19-23; LR 36-40; PDS 12-20. Body moderately elongate and compressed. Head subcylindrical; gill opening not extending anteriorly to a vertical through posterior margin of preopercle; mental flap well developed, slightly protruding posterolaterally; a flap-like projection at tip of anterior nostril; anterior margin of tongue notched. Upper part of pectoral fin with filamentous free rays; pelvic fins united medially; frenum present, with a distinct projection at middle of posterior margin. Scales ctenoid posteriorly, cycloid anteriorly; head naked, except for upper part of operculum with cycloid scales. Sensory canals and pores present on head; longitudinal pattern of sensory papillae on cheek; uniserial transverse row of sensory papillae just behind chin. Color: head and body dark gray or gray blown dorsally, pale gray or white ventrally; a series of small black blotches on midlateral body; may be head and anterior part of body with a broad white saddlelike blotch, as well as small white saddle on caudal peduncle. Size: 5.0 cm SL. Distribution: Indo-Pacific. Remarks: found in shallow rocky shores.