Omobranchus fasciolatoceps (Richardson 1846)

Head without cirri. Both sexes with a fleshy blade-like crest on occiput. Lower end of gill opening above posterior fin base. Sensory pores in infraorbital and interorbital canals usually 8 and 2 respectively

Oviparous, distinct pairing (Ref. 205).

Dorsal spines (total): 12; Dorsal soft rays (total): 19 - 22; Analspines: 2; Analsoft rays: 21 - 24

Adults rarely enter brackish water. Attain less than 8 cm TL. 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).

Omobranchus fasciolatoceps (Richardson)

Blennius fasciolatoceps Richardson, 1846:265 [Macao, based on a then-unpublished illustration].

Petroscirtes dispar Günther, 1861:232 [in part; Amoy, China; name restricted under Omobranchus punctatus].

Chasmodes herklotsi Herre, 1935:288 [southern coast of Hong Kong].

Petroscirtes uekii Katayama, 1941:591 [Higashiiwase of Toyama Bay].

DESCRIPTION (see also Table 5).—Dorsal fin XII, 19–22 = 31–34; anal fin II, 22–24; (Katayama and Ikeda, 1973, reported an anal-fin count of II, 21 for a specimen from Yamaguchi Prefecture, Japan); both anal-fin spines of males discernible externally; segmented caudal-fin rays 12–13 (12 in 1 of 21 specimens); dorsal + ventral procurrent caudal-fin rays 11–13; vertebrae 10 + 27–30 = 37–40; epipleural ribs 11–13 (13 in 1 of 20 specimens); prenasal pores present; interorbital pores 2–3 (2 in 18 of 19 specimens); circumorbital pores 7–8 (8 in 17 of 20 specimens); lateral-line tubes 3–8; lateral-line tubes extending posteriorly to below level of dorsal-fin spine 5–10; gill opening restricted to area dorsal to level of dorsalmost pectoral-fin ray; lower-lip flap present; circumorbital bones 5; lower jaw teeth 26–48 (Figure 41); upper jaw teeth 24–35 (Figure 40); fleshy bladelike crest present on top of head of both sexes.

COLOR PATTERN.—Males: Head: Four moderately narrow to broad, pale to dusky bands on head. Anterior band extending from anteroventral margin of orbit across mouth, just anterior to corner of jaws, onto chin. Second band extending ventrally from orbit, angled slightly posteriorly on ventral side of head. Broad, dark dusky continuation of 1st or 2nd band directed dorsally from dorsal margin of orbit to anterodorsal edge of fleshy crest, covering anterior half of crest. Third band encircling head posterior to eye; above level of mouth band broad, extending onto posterior end of fleshy crest; below level of mouth band narrow, slanted posteroventrally; large, dark dusky to dark oval spot present on band posterior to level of eye; spot well defined all but ventrally, with dark anterior and posterior margins continued dorsally and ventrally on band in some specimens. All 3 bands may be confluent ventrally with corresponding bands of opposite side. Fourth band encircling head just anterior to dorsal-fin origin; ventral end of band terminating just dorsal to pelvic-fin origin (illustration by Tomiyama and Abe, 1953, shows band splitting just below level of eye, and posterior arm of band directed onto fleshy pectoral-fin base; our specimens do not exhibit this pattern but they are faded).

Trunk: Pale to pale dusky with approximately 10 evenly spaced, faint, broad, dusky bands. Bands reaching from dorsal to ventral body contour; dorsal half of bands directed slightly dorsoposteriorly, ventral half slightly ventroposteriorly, bands becoming very faint to absent posteriorly; posterior one-fifth of body apparently without bands.

Pectoral Fin: Pale to transparent with dark specks of pigment scattered basally and concentrated in single threadlike lines along dorsal and ventral edges of each ray.

Pelvic Fin: Pale with dark specks of pigment scattered basally.

Dorsal Fin: Pale with narrow, dark dusky to dark stripes. Two moderately narrow stripes present anteriorly on fin; 3rd stripe appearing distally at about 6th dorsal-fin spine; stripes becoming slightly narrower and turning dorsoposteriorly near last dorsal-fin spine; posterior half of fin with series of narrow, dorsoposteriorly slanted stripes, becoming faint distally. Large, but not prominent, dusky spot present distally between about first 3 segmented dorsal-fin rays in some specimens.

Anal Fin: Dark dusky to dark, tips of rays abruptly pale.

Caudal Fin: Pale with evenly scattered dark specks of pigment; duskier basally.

Females (specimens examined greatly faded): Similar to males except: overall pigment pattern apparently paler, bands fainter; dorsal-fin markings less distinct; dusky spot on dorsal fin apparently absent.

Useful illustrations of O. fasciolatoceps are contained in Tomiyama and Abe (1953, pl. 193) and Whitehead (1969, pl. 25c).

GEOGRAPHIC DISTRIBUTION (Figure 6).—Coast of mainland China from Macao and Hong Kong north to Toyama Bay, Japan. The Macao record is based on the type-locality of Blennius fasciolatoceps. Tomiyama and Abe (1953) described and illustrated a specimen (as O. uekii) from Hamana Lake, Honshu, Japan, which is the northernmost record for the Pacific coast of Japan. Kamohara (1956) reported a specimen (as O. uekii) from the mouth of the Kogami River in Kochi City, Shikoku; we have not recorded this locality on the distribution map because we are unable to verify the identification. Katayama and Ikeda (1973) described and illustrated a specimen (as O. uekii) from the Atsu Higashigawa River in Yamaguchi Prefecture, Japan. We have entered this locality record on the distribution map.

HABITAT.—Tomiyama and Abe (1953) reported O. fasciolatoceps (as O. uekii) from brackish water, and Herre (1934) reported it (as Petroscirtes dispar) from oyster beds.

COMPARISONS.—Omobranchus fasciolatoceps is unique in the Blenniidae in the changes in jaw structure that occur in mature females (see “Sexual Dimorphism” under the generic account). It is otherwise separable from most of the other species of Omobranchus only by a combination of characters. The possession of 2 interorbital pores and a fleshy crest on the head separates O. fasciolatoceps from all the Omobranchus species with which it appears to be broadly sympatric; O. aurosplendidus, elongatus, ferox, germaini, loxozonus, elegans, punctatus. Omobranchus aurosplendidus also has a crest, but it has 3 interorbital pores, more dorsal- and anal-fin elements, more vertebrae, and fewer lateral-line tubes than O. fasciolatoceps (Table 5). The other species have 3, rarely 2 or 4, introrbital pores and no crest.

NOMENCLATURAL

分布於西北太平洋區，包括日本及台灣。台灣產於南部及澎湖等海域。

小型魚類，僅具學術研究價值。

體長橢圓，稍側扁；間鰓蓋骨之腹後側有突起，向後超過上舌骨之後緣。頭頂具冠膜，Springer (1975)描述雌魚的頭頂膜冠與雄魚同高，但兩側較窄；頭上無鬚毛；鰓裂位胸鰭基上方；上下唇平滑，具下唇膜；上下頜具後犬齒。D. XII, 19; A. II, 21; P. 13; V. I, 2。背、臀鰭與尾柄相連。 頭部具4條暗帶，第一與第二條從冠膜至吻及頰部，第三條在冠膜後背中線相接，向下延伸至前鰓蓋，第四條在鰓蓋上；眼後有一卵形大黑點；體側有淺灰黑色帶；背鰭灰色有暗紋；臀鰭黑色；胸鰭基部有黑色紋；尾鰭灰黑色。

主要棲息於河口附近的海水區。

Omobranchus fasciolatoceps is a species of combtooth blenny found in the northwest Pacific ocean, around southern Japan and China.