Omobranchus fasciolatus (Valenciennes 1836)

Body with broad, irregular, dusky bands anteriorly. Males with dusky spot in middle of soft dorsal fin (Ref. 4404).

Oviparous, distinct pairing (Ref. 205).

Dorsal spines (total): 11 - 12; Dorsal soft rays (total): 18 - 19; Analspines: 2; Analsoft rays: 20 - 22

Adults are known from shallow water with rocky bottom, sometimes in tide pools (Ref. 11441). 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 fasciolatus (Valenciennes)

Blennechis fasciolatus Valenciennes in Cuvier and Valenciennes, 1836:287 [based on a then-unpublished figure; neotype designated below].

Petroscirtes striatus Jatzow and Lenz, 1898:512 [junior primary homonym of Petroscirtes striatus Day, 1888, tribe Nemophini, Bawi, Zanzibar].

Petroscirtes vinciguerrae Borsieri, 1904: 211 [Massaua].

Omobranchus cristatus Fraser-Brunner, 1951:214 [tide-pools at Sirah Island, Aden; junior homonym of Petroscrites cristatus Zugmayer, 1913 (= Omobranchus mekranensis)].

DESCRIPTION (see also Tables 5 and 8).—Dorsal fin XI–XII (XII in 95.0% of specimens), 18–19 = 30–31; anal fin II, 20–22; both anal-fin spines of males discernible externally; segmented caudal-fin rays 13; dorsal + ventral procurrent caudal-fin rays 12–15; vertebrae 10 + 26–28 (26 in only 1 of 51 specimens) = 36–38; epipleural ribs 12–16 (16 in only 1 of 53 specimens); prenasal pores present; interorbital pores 2; circumorbital pores 7–9 (8 in 88.9% of specimens); lateral-line tubes 3–8 (5–7 in 90.5% of specimens); lateral-line tubes extending posteriorly to below level of dorsal-fin spine 7–10; gill opening varying from resricted to area dorsal to level of dorsalmost pectoral-fin ray to extending ventrally to opposite 2nd ray (restricted to area dorsal to dorsalmost ray in 95.0% of specimens); lower-lip flap present; circumorbital bones 5; lower jaw teeth 18–26; upper jaw teeth 18–25 (Figure 42); fleshy bladelike crest present on top of head of males over 33 mm SL, present or absent on smaller males, poorly developed or absent on females.

COLOR PATTERN.—Males: Head: Two narrow, dark bands present between anterior margin of orbit and upper lip; row of intense, small, dark spots occasionally present along each band. Three broad, mottled, dark bands on lower half of head; anterior band extending from anteroventral margin of orbit across mouth just anterior to angle of jaws to chin, usually joining corresponding band of opposite side on chin; 2nd band extending ventrally from posteroventral margin of orbit, directed slightly posteriorly at level of anterior preopercular pores; 3rd band extending ventroposteriorly from posterior margin of orbit; cheek portion of 3rd band faint or absent in most specimens; posterior 2 bands usually terminating before reaching ventral midline of head. Underside of head with dusky spots or freckles in spaces between bands and in area posterior to 3rd band, particularly well developed posteriorly; narrow, vertical, dusky streaks or lines of small, dark spots located more dorsally between bands. Large, dusky, oval area directly behind eye, extending from level of upper end of orbit to ventral extent of preopercular pores; intensely dark semicircular spot approximately half size of eye covering dorsal end of oval area; oval area dusky anteriorly and medially, usually paler ventrally and ventroposteriorly; narrow, pale margin along curved dorsal edge of semicircular spot; some specimens with narrow, posteroventrally inclined, pale slash across center of oval area. Operculum generally indistinctly mottled except for narrow, pale slash originating just above pale, dorsal margin of semicircular spot and running diagonally downward across upper portion of operculum; posteroventral portion of operculum sometimes with several tiny, dark spots; posterior opercular membrane pale. Interorbital area occasionally with several broad, dark bands, spots, or blotches continuing dorsally onto fleshy crest.

Trunk: Approximately 17 vertical, broad, dusky to dark bands on body; tips of bands reaching to or near dorsal and ventral body contours, usually becoming fainter ventrally; occasionally 1 or 2 middle bands not reaching as high as adjacent bands: posterior bands often faint and blotchlike; dorsal ends of anterior bands directed slightly anteriorly, posterior bands slightly posteriorly; dorsal ends of bands wavy, giving dorsal one-fourth of body color pattern less regular appearance; some specimens with bands paired, bands in a band pair only slightly closer together than band pairs; pigment along vertical axes of bands slightly intensified; intensification greatest at 3 points, at lateral midline of body, halfway up dorsal half of body, and halfway down ventral half of body, giving appearance of 3 longitudinal rows of dark spots in faded specimens; rows usually not well developed in males; when evident, midlateral row usually best developed.

Pectoral Fin: Fin and fleshy base pale with even spread of dark specks of pigment. Some specimens with about 4 tiny, dark spots evenly spaced along basal edge of fin.

Pelvic Fin: Pale with even spread of dark specks of pigment.

Dorsal Fin: Mostly dusky proximally; membrane pale to transparent distally, usually with slightly dusky edge; spinous portion occasionally with dusky mottling or several dorsoanteriorly slanted, broad, dusky bands proximally, otherwise evenly dusky, except more transparent proximally. Large, intensely dark, oval spot usually present somewhat distally between 9th and 14th segmented rays.

Anal Fin: Pale dusky proximally, dusky to dark distally, tips of rays abruptly pale.

Caudal Fin: Pale with even spread of dark specks of pigment. Vertically oriented pair of diffuse, dusky blotches at base of fin giving rise to 2 diffuse, dusky stripes; stripes may converge into 1 posteriorly.

Females: Similar to males except: body bands largely reduced or fainter; intensifications of pigment in bands usually forming 3 rather distinct rows of dark spots and often a 4th row above anterior portion of dorsal row; other spots often present along vertical axes of bands and dorsally; dorsal and anal fins weakly pigmented, dorsal fin uniformly very pale dusky proximally, transparent distally, dark oval spot in dorsal fin absent.

GEOGRAPHIC VARIATION.—There are slight shifts in the averages for meristic characters in the various populations of O. fasciolatus that may prove to be descriptive of the populations when more specimens are available (Table 8).

GEOGRAPHIC DISTRIBUTION (Figure 4).—Bitter Lakes of the Suez Canal south to Bazaruto Island, Mozambique, and east from Persian Gulf to northwest India; Madagascar. Smith (1959) reported O. fasciolatus (as O. mekranensis) from Malindi and Shimoni, Kenya, Zanzibar (based on Jatzow and Lenz, 1898), and Ibo and Bazaruto Island, Mozambique. We have not seen Smith’s specimens, but based on his description and illustration of a specimen from Ibo, we accept his records and have recorded them on the distribution map.

HABITAT.—Shallow coastal waters and tidepools in rocky areas and under nonestuarine conditions. In the “Material Examined” section, the specimen recorded as having come from Kabret, which is in the Bitter Lakes, is of interest. The specimen was collected by the Cambridge Suez Canal Expedition of 1924, at which time the salinity of the Bitter Lakes was 48.5–53.5 o/oo (Fox, 1926, tables 5 and 11). In view of the ability of O. fasciolatus to exist in this high salinity barrier, it is conceivable that it might penetrate to, and become established in, the Mediterranean Sea.

COMPARISONS.—Omobranchus fasciolatus is separable from most of the other species of Omobranchus only by a combination of characters. It is most easily confused with O. mekranensis, with which it is sympatric (both species have been taken in the same collection). It differs from O. mekranensis most obviously in having 30–31 total dorsal-fin elements (versus 32–33), 10 + 26–28 = 36–38 vertebrae (versus 11 + 28–29 = 39–40), and both anal-fin spines of males discernible externally (versus one or both spines not discernible). Male O. fasciolatus may have a dark spot, which O. mekranensis lacks, near the center of the segmented dorsal-fin rays.

Omobranchus fasciolatus may be most easily separated from the other Omobranchus species (banditus, elongatus, ferox, punctatus, and woodi) with which it appears to be broadly sympatric as follows: from all in having typically 2 interorbital pores (rarely fewer than 3 pores in the other species); from O. banditus in having a lower-lip flap and in lacking prominent, discrete dark bands on the body; from O. elongatus in frequently having a fleshy crest, 12 dorsal-fin spines (usually more than 12 in O. elongatus), the gill opening usually restricted to the area dorsal to the level of the dorsalmost pectoral-fin ray (versus usually extending ventrally to or below 2nd from dorsalmost ray in O. elongatus), and in never having filamentous caudal-fin rays in males; from O. ferox in having 30–31 total dorsal-fin elements (versus 32–35) and in having the gill opening restricted dorsal to the level of the 3rd pectoral-fin ray (versus extending ventral to the second ray in O. ferox), and in frequently having a fleshy crest; from O. punctatus in frequently having a fleshy crest, both anal-fin spines of males discernible externally, 12–16 epipleural ribs (versus 15–25, rarely less than 18 in O. punctatus), and 10 precaudal vertebrae (versus 10–12, rarely 10); from O. woodi in having 10 precaudal vertebrae (versus 11–12), and usually fewer total dorsal-fin elements and vertebrae (Tables 5 and 8).

NOMENCLATURAL

Omobranchus fasciolatus, the Arab blenny or barred Arab blenny, is a species of combtooth blenny found in the western Indian ocean.