Barred Tail Rockskipper

Oviparous, distinct pairing (Ref. 205).

Dorsal spines (total): 13; Dorsal soft rays (total): 14 - 16; Analspines: 2; Analsoft rays: 15 - 17

Found along rocky intertidal shorelines, benches, outer reef flats, and reef margins subject to some degree of wave action.

Adults are found along rocky intertidal shorelines, benches, outer reef flats, and reef margins subject to some degree of wave action. Feeds on filamentous algae (Ref. 89972). 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).

Entomacrodus caudofasciatus (Regan)

In my 1967 (pp. 134–135) revision I described five different color pattern types for this species. Each of the color pattern types, except number 4, was found to be restricted to a particular geographic area. No two color pattern types were found to occur sympatrically. Additional specimens of pattern number 3 (Waigeo, New Britain, New Georgia) are now available from New Guinea (USNM 206385, Trobriand Islands, 11 specimens 21.2–37.2 mm SL; USNM 206386, Madang, 7 specimens, 34.8–50.0 mm SL) and the New Hebrides (AMS 1.14308, 2 specimens, ca. 41–45.8 mm SL). The New Hebrides specimens extend the number 3 pattern type considerably southward. In my description of the number 3 pattern I mentioned that there were no stripes on the upper lip. Several of the new specimens show traces of such stripes.

Several specimens with color pattern number 4 (South China Sea, McKean, Swains, Tutuila, Tau, and Tongatapu islands) from Taiwan represent a slightly northern range extension for this color pattern type (USNM 206384, 3 specimens, 42.8–43.9 mm SL; USNM 206387, 11 specimens, 35.6–58.4 mm SL; USNM 206398, 7 specimens, 44.5–61.4 mm SL).

Recent collections of E. caudofasciatus from Ducie Island (BPBM uncataloged, 2: 31.5–35.1 mm SL) and Pitcairn Island (BPBM uncataloged, 9: 40.5–55.0 mm SL) represent a westward range extension for color pattern number 5, formerly reported only for Tahiti, Makatea, Rarotonga and Raroia.

Entomacrodus thalassinus (Jordan and Seale)

The following specimens are range extensions for the subspecies of E. thalassinus:

E. t. thalassinus: Ceylon, USNM 206399 (12 specimens, 19.0–36.6 mm SL); One Tree Island, Great Barrier Reef, USNM 201366 (30.8 mm SL); Trobriand Islands, New Guinea, USNM 206406 (23.6 mm SL).

E. t. longicirrus Springer: Southwest tip of Taiwan, USNM 206393, 206395, 206396 (6 specimens 28.6–34.8 mm SL).

E. t. thalassinus and E. t. longicirrus were differentiated by me on the basis of relative supraorbital cirrus lengths. E. t. longicirrus was reported only from Thailand, Viet Nam, and Hong Kong. All specimens from outside these South China Sea localities belonged to the nominal subspecies. The specimens here reported from Taiwan, a locality somewhat intermediate between the South China Sea and the other areas, are of interest because they are also somewhat intermediate on the basis of relative supraorbital cirrus lengths: four of the specimens fall at the lower end of the range of E. t. longicirrus for relative cirrus lengths and two fall within the range of E. t. thalassinus.

分布於印度-太平洋區，由安達曼至杜夕群島，北至日本，南至拉帕。台灣分布於南部、東部、小琉球、蘭嶼及綠島等海域。

小型魚類，僅具學術研究價值。

體延長形，稍側扁，似圓柱狀；頭鈍短。頭頂無冠膜；頸部無葉片狀皮瓣，僅有一低皮褶，單一不分支；鼻鬚掌狀分支；眼上鬚1-8。上唇僅兩側具鋸齒緣，中間平滑；下唇平滑。齒骨具一犬齒。D. XIII-XIV, 14-15；A. II, 16-17； P. 14；V. I, 4。背鰭具深缺刻，最後一棘小，背鰭與尾柄相連，臀鰭不與尾柄相連，雄魚臀鰭各棘及第二與第三軟條頂端膨大；尾鰭鰭條分叉。頭部具不規則圖案，頭部下方有鑲白邊之Λ形深紋，胸鰭後上方有大黑斑，腋下黑色；體側具成對淺色帶以及5列成對黑點；背鰭硬棘部和臀鰭灰黑色，鰭緣黑褐色；背鰭軟條色淡具斜紋，鰭緣黑色，尾鰭有4條黑色點帶。

主要棲息於沿岸潮間帶礁石潮池區，深度3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。