Journal of the Ocean Science Foundation
Info
Chromis sahulensis is currently known only from northwestern Australia, the documented range extends from near Evans Shoals off Melville Island in the Northern Territory southward to the Shark Bay region in Western Australia,
a linear distance of about 2,650 km!
.
Preferred habitat of damselfish is the outer slope of coral reefs and the gradually sloping or shallow bottom of trawling areas, probably near rocks, sponges, and sea fans.
Adult Chromis are generally yellowish brown on the back, dorsal head, and nape, turning gray, often with a silvery sheen with a silvery sheen.
A conspicuous white spot (size about half the pupil) is clearly visible near the base of the last dorsal fin rays as a saddle-shaped spot extending to the upper caudal peduncle.
The iris of the eye is predominantly golden yellow, the dorsal fin pale brown, translucent at the rearmost rays with a yellowish submarginal band and a narrow whitish to pale gray outer margin.
The anal fin is dark gray, translucent at the posterior region with a narrow blue anterior margin; the caudal fin is translucent with distinct brown bands and narrow blue-white margins at the upper and lower margins.
Both pelvic fins are translucent whitish with a narrow white anterior margin; pectoral fins are also translucent with a black spot covering the outer part (fin side) of the fin axis and slightly overlapping the dorsal margin of the fin base.
Juveniles are very similar to adults, but slightly paler overall.
Remarks.
Similar to Chromis norfolkensis, this species was previously identified as a population of Chromis fumea.
However, it differs from Chromis fumea in having more gill ruffles on the first astial arch, and there are also notable differences in coloration:
While both species have conspicuous dark bands on the caudal fin, these are brownish in Chromis sahulensis, while they are black in Chromis fumea.
Unlike C. fumea, C. sahulensis is yellowish on the upper head and dorsum. and C. fumea is often yellowish on the lower half of the body, while C. sahulensis is uniformly gray.
Judging from the underwater photographs, the white spot near the base of the last dorsal fin rays is rather saddle-shaped and extends further out onto the caudal fin peduncle in Chromis sahulensis,
while in Chromis fumea it is more rounded and barely extends onto the peduncle.
There is also a significant size difference between the two species, with Chromis sahulensis reaching only about 60 mm SL, while Chromis fumea reaches at least 95 mm SL in Chromis fumea.
Etymology. This species is named for its geographic range, which is restricted to the Sahul Shelf, the portion of the continental shelf off the northwestern coast of Australia.
Scientific source:
Allen, Gerald R., & Allen, Mark G. (2021).
Two new species of Chromis (Teleostei: Pomacentridae) from northwestern Australia and the southwestern Pacific Ocean, previously part of C. fumea (Tanaka, 1917).
Journal of the Ocean Science Foundation, 38, 78–103. https://doi.org/10.5281/zenodo.5601971
a linear distance of about 2,650 km!
.
Preferred habitat of damselfish is the outer slope of coral reefs and the gradually sloping or shallow bottom of trawling areas, probably near rocks, sponges, and sea fans.
Adult Chromis are generally yellowish brown on the back, dorsal head, and nape, turning gray, often with a silvery sheen with a silvery sheen.
A conspicuous white spot (size about half the pupil) is clearly visible near the base of the last dorsal fin rays as a saddle-shaped spot extending to the upper caudal peduncle.
The iris of the eye is predominantly golden yellow, the dorsal fin pale brown, translucent at the rearmost rays with a yellowish submarginal band and a narrow whitish to pale gray outer margin.
The anal fin is dark gray, translucent at the posterior region with a narrow blue anterior margin; the caudal fin is translucent with distinct brown bands and narrow blue-white margins at the upper and lower margins.
Both pelvic fins are translucent whitish with a narrow white anterior margin; pectoral fins are also translucent with a black spot covering the outer part (fin side) of the fin axis and slightly overlapping the dorsal margin of the fin base.
Juveniles are very similar to adults, but slightly paler overall.
Remarks.
Similar to Chromis norfolkensis, this species was previously identified as a population of Chromis fumea.
However, it differs from Chromis fumea in having more gill ruffles on the first astial arch, and there are also notable differences in coloration:
While both species have conspicuous dark bands on the caudal fin, these are brownish in Chromis sahulensis, while they are black in Chromis fumea.
Unlike C. fumea, C. sahulensis is yellowish on the upper head and dorsum. and C. fumea is often yellowish on the lower half of the body, while C. sahulensis is uniformly gray.
Judging from the underwater photographs, the white spot near the base of the last dorsal fin rays is rather saddle-shaped and extends further out onto the caudal fin peduncle in Chromis sahulensis,
while in Chromis fumea it is more rounded and barely extends onto the peduncle.
There is also a significant size difference between the two species, with Chromis sahulensis reaching only about 60 mm SL, while Chromis fumea reaches at least 95 mm SL in Chromis fumea.
Etymology. This species is named for its geographic range, which is restricted to the Sahul Shelf, the portion of the continental shelf off the northwestern coast of Australia.
Scientific source:
Allen, Gerald R., & Allen, Mark G. (2021).
Two new species of Chromis (Teleostei: Pomacentridae) from northwestern Australia and the southwestern Pacific Ocean, previously part of C. fumea (Tanaka, 1917).
Journal of the Ocean Science Foundation, 38, 78–103. https://doi.org/10.5281/zenodo.5601971
