GOBIIDAE Istigobius diadema, 8.0 cm SL (photo by Koichi Shibukawa) Istigobius diadema (Steindachner, 1876) Black-lined Lagoon Goby D VI+I, 11; A I, 9; P1 19; LR 31-33; PDS 18. Body moderately elongate and compressed. Head slightly depressed; snout rounded, slightly projecting beyond upper jaw; lower jaw not projecting beyond upper jaw; gill opening not extending anteriorly to a vertical through preopercular margin. Pelvic fins united medially; frenum present. Scales ctenoid, excepting operculum, occipital region, breast and pectoralfin base with cycloid; other part of head naked. Sensory canals and pores present on head; longitudinal pattern of sensory-papillae rows on cheek; aggregation of sensory papillae just behind chin. Color: head and body pale grayish brown, with a distinct horizontal black band behind eye. Size: 10.0 cm SL. Distribution: eastern Indian Ocean, Andaman Sea and Indonesia. Remarks: Found in mangrove areas and bays with sandy or muddy bottoms.