Istiblennius muelleri (Klunzinger, 1879)
Mueller's rockskipper
photo by The Fish Database of Taiwan

Family:  Blenniidae (Combtooth blennies), subfamily: Salariinae
Max. size:  7 cm SL (male/unsexed); 5.5 cm SL (female)
Environment:  demersal; marine; depth range 0 - 1 m
Distribution:  Western Pacific: Hsiao-liu-chiu Island, off southwestern Taiwan; south to Kur Island, Indonesia.
Diagnosis:  Dorsal spines (total): 12-14; Dorsal soft rays (total): 19-21; Anal spines: 2; Anal soft rays: 21-23. Dorsal fin XII-XIV, 19-21; membrane between spinous and segmented-ray portions notched deeper than half length of first segmented ray; membrane from posteriormost ray beginning from between dorsal edge of caudal peduncle at caudal-fin base (rarely) to dorsal edge of caudal fin up to 18% caudal-fin length in specimens ? 3 cm SL; anal fin II, 21-23 (23 only in males); pectoral-fin rays 13-14; vertebrae 10+27 to 30 = 37 to 40 (rarely 40); lacking nape cirrus; orbital cirrus simple, rarely a single branch or a few short, fine filaments at tip, typically shorter than orbital diameter; nasal cirrus simple, relatively long (typically half orbital diameter); lateral line canal continuous anterodorsally with simple pores (no vertical pairs), extending posteriorly to between verticals from bases of 6th and 9th dorsal-fin spines (usually to between verticals from 7th and 8th spines), then continuing posteriorly and posteroventrally as series of 1-6 (rarely 1 or 6) short, disconnected, horizontally bi-pored canals/tubes in skin; posteriormost tube area below and between verticals from bases of 7th spine and second segmented dorsal-fin ray (rarely posterior to vertical from 12th spine); mandibular pores 3-5; lacking posterior canines; ventral margin of upper lip and dorsal margin of lower lip entire; both sexes from ?3 cm SL with well-developed, fleshy, blade-like crest on dorsal part of head; crest of females comparatively smaller than males’; spinous portion of dorsal fin dusky, crossed by several diagonal, paler-dusky stripes with dark margins; segmented ray portion faint dusky with numerous dark pinstripes coursing length of fin, stripes coalescing into reticular pattern posteriorly. Male max. size ca 7 cm SL; female max. size ca 5.5 cm.
Biology:  Adults occur in tide pools and close to edge of rocky shores at low tide. Oviparous. Eggs are demersal and adhesive (Ref. 205), and are attached to the substrate via a filamentous, adhesive pad or pedestal (Ref. 94114). Larvae are planktonic, often found in shallow, coastal waters (Ref. 94114).
IUCN Red List Status: Least Concern (LC); Date assessed: 27 March 2009 Ref. (130435)
Threat to humans:  harmless
Country info:  Museum: Homonhon I., USNM 123361. Simaluc I., USNM 122435. Negros, Dumaguete, CAS 46498; Ciagba Bay, CAS 66856. Mindoro, Calapan, CAS-SU 32304, Iba I., CAS-SU 32305. Tataan, Tawi-Tawi Group, USNM 122436(Ref. 9962). Also Ref. 90102.


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