Abyssal Triggerfish, Rhinecanthus abyssus Matsuura & Shiobara 1989

Summary:

A pale greyish triggerfish with a yellowish-orange tinge on the dorsal half of the body, narrow black lines in the dark brown band running from the interorbital region to the pectoral-fin base, a large black blotch around the anus, a broad black bar on the caudal peduncle edged anteriorly and posteriorly with a bluish white line, a broad black band from the eye to the pectoral-fin base, three black lines across the interorbital region, a yellow caudal fin with a broad pale outer margin, and a crescent-like orange line in the membrane of the first dorsal fin.

Cite this page as:

Bray, D.J. 2023, Rhinecanthus abyssus in Fishes of Australia, accessed 27 Apr 2024, https://fishesofaustralia.net.au/Home/species/5724

Abyssal Triggerfish, Rhinecanthus abyssus Matsuura & Shiobara 1989

More Info

Distribution	Reefs in the Coral Sea (Jewell Reef and Holmes Reef). Elsewhere the species occurs in the western Pacific: Indonesia (Sulawesi), southern Japan (Ryukyu Islands and Yaeyama Island), and possibly Thailand. Inhabits mesophotic reefs.
Features	Dorsal fin III,22-23 (first two rays in second dorsal fin unbranched); Anal fin 19-20 (first two rays unbranched); Pectoral fin 13-15 (first dorsal-most and ventral-most ray unbranched); Head scale rows 27-29; Body scale rows 40-42. Body relatively elongate, the greatest depth 2.0 in SL; snout long, 3.1 in SL; longest dorsal soft ray 3.4-3.6 in head length (HL) and longest soft anal ray 3.5-3.7 in HL. Caudal peduncle short, tapering toward base of caudal fin, with 4-5 longitudinal rows of small antrorse spines on each side , the inner 2 rows developed, the other rows small and weak.
Colour	Dorsal half of body brownish grey with yellowish-orange tinge, ventral half white; a large elliptical black area around anus; a broad black bar on caudal peduncle, edged with bluish-white anteriorly and posteriorly; a wide dark brown band tapering from interorbital region through eye toward pectoral-fin base; three narrow black lines in this dark brown band originating at the dorsal edge of eye and crossing the interorbital region to the opposite eye; a narrow black line running from postero-ventral edge of eye to ventral part of gill opening, continuing onto pectoral-fin base; a narrow yellow line on proximal part of pectoral fin; first dorsal fin dark brown with a reddish-brown line curving from above the second dorsal-spine base to below the second dorsal-spine tip; basal sheath of second dorsal fin dark brown; second dorsal, anal and pectoral fins pale; caudal fin yellow anteriorly, pale posteriorly (Matsuura & Peristiwady 2011).
Remarks	The Abyssal Triggerfish is the only species in the genus Rhinecanthus known to inhabit deep waters.
Similar Species	Differs from the similar Halfmoon Triggerfish, *Rhinecanthus lunula*, in lacking a semicircular white marking on rear side of body.
Etymology	The specific name is from the Greek abyssos (= deep), "in reference to the depths of 130-150m where it was caught. The other species of Rhinecanthus are well known for their predilection for shallow water."
Species Citation	Rhinecanthus abyssus Matsuura & Shiobara 1989, Japanese Journal of Ichthyology 36(3): 315, Fig. 1. Type locality: Off northeastern coast of Kume-jima Island, Ryukyu Islands, Japan, 26°21.0'N, 126°50.5'E, depth 150 m.
Author	Bray, D.J. 2023
Resources	Atlas of Living Australia Australian Faunal Directory Catalog of Fishes

Abyssal Triggerfish, Rhinecanthus abyssus Matsuura & Shiobara 1989

References

Matsuo, R. & Hibino, Y. 2021. First record of a rare triggerfish, Rhinecanthus abyssus (Tetraodontiformes: Balistidae) from Ishigaki Island, Yaeyama Islands, Japan. Ichthy, Natural History of Fishes of Japan 4: 9-11. https://doi.org/10.34583/ichthy.4.0_9 (in Japanese)

Matsuura, K. 2022. Rhinecanthus abyssus. The IUCN Red List of Threatened Species 2022: e.T193797A2278703. https://dx.doi.org/10.2305/IUCN.UK.2022-2.RLTS.T193797A2278703.en. Accessed on 21 September 2023.

Matsuura, K. & Peristiwady, T. 2011. Second record of the rare triggerfish, Rhinecanthus abyssus Matsuura and Shiobara, 1989 (Actinopterygii, Tetraodontiformes, Balistidae) from Sulawesi, Indonesia. Bulletin of the National Science Museum, Series A, 37: 217–219 See ref online

Matsuura, K. & Shiobara, Y. 1989. A new triggerfish, Rhinecanthus abyssus, from the Ryukyu Islands. Japanese Journal of Ichthyology 36(3): 315-317. https://doi.org/10.11369/jji1950.36.315