Blenny

Dark spot distally between 1st 2 dorsal spines; (Ref. 4404). Males with about 6 dusky bands on body; females with bands that tend to form vertical rows of dusky spots; dusky spots on dorsal and caudal fins; anal fin uniformly dusky (Ref. 4404).

Oviparous, distinct pairing (Ref. 205).

Dorsal spines (total): 12 - 14; Dorsal soft rays (total): 19 - 24; Analspines: 2; Analsoft rays: 21 - 25

Often found in mangrove areas (Ref. 9962). Inhabits sheltered rocky shorelines and mangroves (Ref. 37816).

Euryhaline. Adults are often found in mangrove areas (Ref. 9962). They inhabit sheltered rocky shorelines and mangroves (Ref. 37816). 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).

fisheries: of no interest

Istiblennius dussumieri (Valenciennes)

Salarias dussumieri Valenciennes in Cuvier and Valenciennes, 1836:310 [Malabar; lectotype, designated in nomenclatural discussion section below, larger of 2 syntypes in MNHN A.1740]).

Salarias forsteri Valenciennes in Cuvier and Valenciennes, 1836:315 [Pacific Ocean; designated in nomenclatural discussion section under Istiblennius edentulus, larger of 2 syntypes in ZMB 1942].

Salarias olivaceus Blyth, 1859:271 [Port Blair, eastern coast of the southern island of Great Andaman; neotype, USNM 242052, designated in nomenclatural discussion section below].

Salarias striatomaculatus Kner and Steindachner, 1866:366 [Mauritius; holotype, apparently lost].

Salarias geminatus Alleyne and Macleay, 1877:336 [Torres Straits; AMS I.16416-001, 2 presumable syntypes].

Salarias auridens Alleyne and Macleay, 1877:338 [Darnley Island; AMS I.16418-001, holotype].

Salarias cristiceps Alleyne and Macleay, 1877:338 [Darnley Island; AMS I.16417-001, holotype].

Salarias doliatus Sauvage, 1880:217 [Océan atlantique; MNHN 2548, holotype].

Salarias cheverti Macleay, 1881:12 [Darnley Island; AMS I.16419-001, presumed syntypes].

Scartichthys stigmatopterus Fowler, 1904:553 [Padang, Sumatra; ANSP 27803, holotype].

Salarias zamboangae Evermann and Seale, 1906:512 [Zamboanga, Mindanao; USNM 55623, holotype].

Salarias barbatus Gilchrist and Thompson, 1908:108 [Bluff, Durban; 2 syntypes, SAM 9891].

Salarias siamensis H.M. Smith, 1934:320 [Koh Tao, Gulf of Siam; holotype apparently lost].

Salarias oortii [not Bleeker), Chapman, 1951:325,328 [misidentification].—Smith-Vaniz and Springer, 1971:58 [misidentification].

DESCRIPTION.—Dorsal fin (Table 34). XII to XIV,19 to 24 = 32 to 37 (XIII in 93% of specimens; 19 in only 5 of over 600 specimens examined for character); mean number of total elements for males from any locality usually higher than that of females from same locality (higher for 17 of 20 localities where means for both sexes are available, statistically significantly higher for 11 of the 17 localities); membrane between spinous and segmented-ray portions notched more than half length of first segmented ray (usually more than two-thirds length); membrane from posteriormost ray attaching to point ranging from on dorsal edge of caudal peduncle anterior to caudal-fin base to point less than 21% caudal-fin length out on dorsal edge of caudal fin (attachment usually on caudal fin in specimens >40 mm SL, usually out on fin <16% fin length).

Anal fin (Tables 34 and 35). II,21 to 25; mean number of segmented rays for males from any locality usually higher than that of females from same locality (higher for 16 of 20 localities where means for both sexes are available, statistically significantly higher for 7 of the 16 localities); posteriormost ray split to base or simple (modal condition varying with population; see section below on geographic variation; posterior element of split ray often difficult to determine externally), not bound by membrane to caudal peduncle in more than 96% of specimens. Mature males with skin covering anal-fin spines and distal half of rays rarely, if ever, expanded, never crinkled along lateral edges.

Pectoral-fin rays 13 to 15 (13 only unilaterally; 14 bilaterally in 94%, unilaterally in 5%, of specimens examined for character).

Pelvic-fin segmented rays 3.

Caudal fin (Table 36). Dorsal procurrent rays 5 to 9 (rarely 5 or 9), ventral procurrent rays 5 to 8 (rarely 5), modal combination , , or , depending on population (see section below on geographic variation); segmented rays 12 to 14 (13 in 99% of specimens).

Vertebrae (Table 34). 10 or 11+27 to 32 = 38 to 42 (10 in 92% of specimens examined for character; 27 in only 2 of 420 specimens examined for character); mean number of total vertebrae usually higher for males from any locality than for females from the same locality (higher for 17 of 20 localities where means for both sexes are available, statistically significantly higher for 7 of the 17 localities); posteriormost pleural rib on 10th to 12th from anteriormost centrum (on 11th in 94% of specimens); posteriormost epineural on 14th to 21st from anteriormost centrum (rarely on 14th or 21st).

Cirri (specimens over 40 mm SL). Nape cirri absent. Orbital cirrus highly variable within and among populations, often appearing damaged or malformed; normal appearing cirri branched, usually comprising elongate, transversely placed pennant with usually no more than 5 branches (cirri) on each medial and lateral edge; cirri of males generally longer than those of females, often longer than orbital diameter; female cirrus rarely as long as orbital diameter; pennant of some specimens from New Caledonia with additional branches arising from low, median keel on anterior surface, other branches arising from posterior surface. Nasal cirri short, variable, usually irregularly palmate with less than 7 finger-like branches, variably a simple flap or broad, folded flap with up to at least 16 tiny branches.

Table 34.—Frequency distributions for certain meristic characters in male and female specimens of Istiblennius dussumieri from various localities. Underlining indicates significant differences between means of sexes from same locality (p ≤ .05).

Table 35.—Frequencies for condition of posteriormost anal-fin ray in specimens of Istiblennius dussumieri from various localities (modes underlined; N = anal-fin ray simple; S = anal-fin ray split to base).

Lateral line. Continuous canal anterodorsally with simple pores (no vertical pairs of pores), extending posteriorly to point between verticals from 4th and 10th dorsal-fin spines (between 7th and 9th spines in 93% of specimens examined for character), continuing posteriorly and descending to midside in specimens >30 mm SL, as series of 1 to 11 (3 to 7 in 92% of specimens) short, disconnected, horizontally bi-pored canals (tubes) in skin; posteriormost tube in area between verticals from 9th dorsal-fin spine and 3rd segmented ray (between 9th spine and 1st ray in 95% of specimens).

Mandibular pores 4 to 6 (5 pores bilaterally in 91%, unilaterally in 7% of specimens; 6 pores only unilaterally (in only 4 of 202 specimens examined for character).

Five to 8 sensory pore positions between 1 o'clock and 5 o'clock on postorbital margin (6 in 88% of over 200 specimens examined for character); 0 to 3 positions with paired pores (0 in 32%, 1 in 48%, 2 in 18%, and 3 in only 1 of over 200 specimens examined for character). Posterior canines present or absent (on one or both sides), often tiny, inconspicuous; smallest male (of 196 examined for character) with canines, 26 mm SL (canines barely evident), but canines present in only 19% of 75 males <50 mm SL, and 68% of 121 males >49 mm; smallest female (of 181 examined for character) with canines, 50 mm SL, but canines present in only 9% of 114 females >49 mm SL.

Ventral margin of upper lip and dorsal margin of lower lip entire.

Males with fleshy, blade-like crest dorsally on head; earliest indication of beginning crest a darkly pigmented, longitudinal line mid-dorsally on head; definite ridge or crest variably present in males as small as 23 mm SL, but usually absent at lengths <29 mm SL; crests present in all males >30 mm, except those from South Africa; crests absent in males <38 mm SL from South Africa. Crests absent in all females, but almost unnoticeable mid-dorsal ridge present in few large females.

Color pattern (in preservative). Males (Figures 45a, 46a,b). Head dark dusky, without distinct markings. Body dark dusky anteriorly with 1 or 2 slightly darker bands dorsally in area below anterior 8 dorsal-fin spines, followed posteriorly with up to 5+ pairs of dusky bands, posteriormore bands sometimes composed of small, dusky spots on ventral half of body, particularly in small males. Spinous dorsal fin usually with dark spot covering some portion of interradial membranes between first and third spines; several wavy, dusky stripes coursing through spinous dorsal fin, or fin generally dark dusky, except pale basally and distally; segmented-ray portion of dorsal fin with slender, pale distal margin and broad, dusky, submarginal stripe or series of dark dashes forming submarginal stripe or stripes; paler, variably marked area below submarginal stripe, subtended by basal dusky area into which body bands diffusely enter. Anal fin dusky overall, darker distally. Caudal fin variably marked, often with pale, distal, dorsoposterior edge, followed proximally by distinctive, broad, dusky, crescentic margin on remainder of fin; crescentic marking continuous with central, dusky stripe originating basally on fin as vertical pair of dusky spots (this pattern not clearly discernible in our illustrations; Randall et al., 1990:384, top fig.; J.L.B. Smith, 1959, fig. 7; and H.M. Smith, 1934, pl. 14 present reasonable renderings of the male color pattern, particularly the caudal fin); dorsal portion of dusky crescentic marking often broken into several dark spots, which appear to be continuations of dorsal-fin spotting. Fleshy pectoral-fin base often with one or two irregular, diagonal, dusky bands; large, diffusely dusky area basally on central rays often present; sometimes 1 or 2 intensely dark spots also present. Pelvic fins dusky without distinctive markings.

Allen and Steene (1987, pl. 107: fig. 3) provide color photograph of head and anteriormost part of body of living male: head generally pale with brownish markings in interorbital region and posterior to eye; iris of eye with coppery brown marks; fleshy crest, dusky brown with pale central band; 2 brown bands separated by pale area on fleshy pectoral-fin base.

Table. 36—Frequency distributions for numbers of procurrent caudal-fin rays in specimens of Istiblennius dussumieri from various localities.

Female (Figures 45e, 46c,d. Head similar to male, but often with series of broad, alternating, pale and dusky bands on upper lip (beginning with pale corners of lip). Body bands of same number as in males; anterior bands indistinct, others often composed in whole or in part of (or superimposed with) dark spots. Spinous dorsal fin with 3 or 4 rows of dark spots on spines or with wavy, dark stripes; small, dark spot sometimes present on membrane between first 2 spines; segmented-ray portion of dorsal fin spotted or striped. Anal fin faint to dark dusky, paler basally; caudal fin varying from almost unspotted (particularly ventral half of fin in some Indian Ocean females) to having 3 or 4 irregular columns of distinct, dark spots on rays; vertical pair of elongate, dark spots usually present at central base of fin. Pectoral and pelvic fins similar to those of males.

Allen and Steene (1987, pl. 107: fig. 4) present in-habitat color photograph of live or freshly dead female with distinctive pale markings on head, body, and pectoral-fin base, and dark spots on anterior dusky body bands; dusky markings on head and body various shades of brown or gray.

Ophioblennius-stage specimens. Only 1 ophioblennius-stage specimen available (UF 31308, 18.5 mm SL from Flores, tide pools; Figures 4b, 6c): 1 enlarged, laterally recurved canine tooth on each side of lower jaw; immediately anterior to canine tooth on right side (only), 2 pointed, anteriorly directed teeth, about half size of canine; pectoral fins bear dark melanophores near tips of rays and/or between rays; small, round cluster of fainter melanophores near proximal ends of central pectoral-fin rays; other pigment consisting mostly of large, faint, expanded melanophores covering brain area.

The ophioblennius-stage specimen was taken in the same collection with a metamorphosed juvenile 18.9 mm SL (UF 92360) and several other specimens 28.2 to 59.7 mm SL (UF 31299). The ophioblennius-stage specimen is the only specimen smaller than 18.9 mm among our material.

Size. Largest male, 109 mm SL; males commonly >90 mm; 4 largest females available, 80 to 98 mm SL, all other females <76 mm SL.

GEOGRAPHIC VARIATION.—There is considerable variation in mean numbers of dorsal- and anal-fin ray and vertebral numbers among specimens from different localities (Table 34). In general, means for these counts are highest at localities in the southwest Pacific, intermediate in the western Indian Ocean, and lowest in the central, western Pacific. On the other hand, mean numbers of procurrent caudal-fin rays (Table 36) are generally higher at western Indian Ocean localities, and lower at other localities. There is a tendency for the modal condition for the terminal anal-fin ray (Table 35) to be split in Indian Ocean specimens and simple (unsplit) in Pacific Ocean specimens. See also color pattern description of females.

Four male specimens (MNHN 4771), which were originally cataloged as having been collected by Banaré from “Indes Orientales,” have higher mean numbers of dorsal and anal-fin rays and total vertebrae than do males from other localities. In general, these means agree most closely with those of male specimens from New Caledonia and Fiji, in the southwest Pacific (Table 34), and we believe it probable that they were taken in that area. Considering that, we wrote Dr. M.-L. Bauchot, MNHN, to determine if more data were available that might have bearing on the provenance of the specimens. In response, she wrote us that the specimens were sent by “Armand, Aubin Banaré, né le 1.03.1836 à la Martinique, est embarqué comme lieutenant de vaisseau en 1863 sur ‘la Fine,’ en Novelle-Calédonie. Il sert sur divers bâtiments de 1863 à 1866 dans cette même région et on le retrouve encore en 1867 en Nouvelle-Calédonie où il fait des travaux d'hydrographie.” The specimens were registered 20 Sep 1867. Bauchot feels certain that the originally assigned locality was erroneous and “qu'il n'y a plus de doute sur l'origine [= New Caledonia] de nos poissons envoyés par Banaré.” It is noteworthy that all 4 of the males, which range in size from 52–76 mm SL, have a simple cirrus on each anterior nostril, an unusual condition for such large specimens of I. dussumieri, and not duplicated in our other specimens from New Caledonia.

COMPARISONS AND RELATIONSHIPS.—We have no strong intuitive suggestion as to what the sister group of I. dussumieri might be, although our phylogenetic analysis places it in a polytomous monophyletic clade with I. edentulus, I. meleagris, and I. rivulatus (Figure 60; see Phylogenetic Analysis section). The distinctive color pattern on the caudal-fin of many males (see color-pattern description above) appears to occur otherwise only in males of I. lineatus (see Comparisons and relationships section under Lineatus Species Complex). Other characters of I. dussumieri occur in various combinations in other species of Istiblennius. The combination of: smooth lips, branched orbital cirri, no nape cirri, posteriormost bi-pored lateral-line tube anterior to vertical from 3rd dorsal-fin spine, and modally 5 mandibular pores, 13 dorsal-fin spines, and posterior canine teeth present (occasionally) on the dentaries, distinguishes I. dussumieri from all other species of Istiblennius.

DISTRIBUTION (Figure 70).—Istiblennius dussumieri is distributed throughout much of the Indo-west Pacific, purportedly even entering the southeasternmost Atlantic Ocean marginally at the Cape of Good Hope (based on a specimen reported by Günther, 1861:562; we believe its occurrence at the Cape of Good Hope is rare, probably only as the result of straggling). Well-documented collections of I. dussumieri have been made from southern Africa east to Palau, northwest to northern Taiwan and southeast to Fiji. A single specimen, in poor condition, is available from Lord Howe Island, the southernmost occurrence in the the Pacific Ocean. The species appears to be absent (although not necessarily unreported) from the Red Sea, Persian Gulf, Sri Lanka, and Christmas, Cocos-Keeling (Smith-Vaniz, pers. comm.), Chagos, and Mariana islands, all of Australia except the northern Great Barrier Reef, and all islands on the Pacific plate.

Borodin (1932) reported I. dussumieri, as Salarias dussumieri, from Apia, Samoa, and Huahine, Society Islands, both on the Pacific Plate. We have examined these 2 specimens, which are housed in the Vanderbilt Marine Museum, and find them both to be Entomacrodus striatus. Fowler (1938) reported I. dussumieri, also as S. dussumieri, from Palmyra, Line Islands, on the Pacific plate. Fowler's record is based on 2 small specimens in poor condition (ANSP 82162, ~ 22.6 and 25.5 mm SL). These specimens are referable to Istiblennius, but we are unable to identify the species. We believe it highly unlikely that they represent I. dussumieri.

Istiblennius dussumieri is a shallow-dwelling species, often taken intertidally and at depths less than 1 m in rocky areas. It may occur together with I. edentulus.

NOMENCLATURAL VARIATION.—Modal counts for position of the terminal pleural rib and numbers of procurrent caudal-fin rays of specimens from Laysan, westernmost island in the distribution of I. zebra, are at the lower ends of the ranges for these elements compared with modes for the same characters for other, more eastern, islands (Table 37).

COMPARISONS AND RELATIONSHIPS.—Istiblennius zebra subjectively appears to us to be most closely related to the allopatric I. bellus, with which it falls into a weakly supported polytomous clade, which also includes I. muelleri, in our phylogenetic anyalysis (Figure 60, see Phylogenetic Analysis section). The highly variable and irregularly formed nasal cirrus (difficult to describe precisely), often consisting only of a simple flap (always simple in muelleri), is a character shared by these 2 species. The 2 species differ most noticeably in the strikingly different color patterns of the females as well as in the presence of a fleshy head crest in females of I. zebra and its absence in I. bellus. Additionally, in I. zebra the upper lip crenulae are absent or scarcely noticeable (in contrast to well developed in I. bellus) and the orbital cirrus is relatively longer, the dorsal fin connected relatively farther out on the caudal fin, and means for numbers of dorsal- and anal-fin elements and total vertebrae are much higher than in I. bellus.

DISTRIBUTION (Figure 66).—Known only from the Hawaiian Islands, from Hawaii northwestward only to Laysan. Generally restricted to supra- or inter-tidal pools on rocky shores; rarely taken from submerged reefs (Strasburg, 1956:254; Phillips, 1977:1–2); standing out of water on spray-wetted rocks at night (Phillips, 1977:21).

NOMENCLATURAL

分布於印度-西太平洋區，由非洲東岸至斐濟，北至台灣，南至若福克島等。台灣分布於南部、東北部、北部、小琉球及澎湖等海域。

小型魚類，僅具學術研究價值。

體長橢圓形，稍側扁；頭鈍短。雄魚頭頂具冠膜，雌魚無。鼻鬚及眼上鬚掌狀分支；無頸鬚。上下唇平滑；無犬齒。D. XII-XIV, 19-20； A. II, 22-24； P. 14；V. I, 3背鰭具缺刻，最後一棘小，背鰭與尾柄相連，臀鰭不與尾柄相連，除了成熟大雄魚外，臀鰭棘很小且埋入皮內。 雄魚體側的橫帶不規則；背鰭第一與第二棘間有一黑斑；背鰭軟條部和尾鰭上半部為灰白色，活魚時為橙黃色斑紋或斑點，而背鰭軟條部有白色斜紋。雌魚體側橫帶較清晰；背鰭第一與第二棘間無黑斑；背、臀及尾鰭上有許多列黑色斑點。

主要棲息於沿岸潮間帶礁石潮池區，深度5公尺內，常藏身於洞穴或縫隙內，受驚嚇時可見其用一前一後的方式跳躍於潮池與空氣間。以藻類、碎屑和小型無脊椎動物為食。

Istiblennius dussumieri, the streaky rockskipper, is a species of combtooth blenny found in coral reefs in the western Pacific and Indian Oceans. It is also commonly known as the Dussumier's rockskipper, streaky dussumier, or the Dussumier's blenny.

Euryhaline. Sometimes found in mangrove areas and brackish water (Ref. 4342).