Monday, February 13, 2023

[Ichthyology • 2023] Coradion calendula • A New Butterflyfish (Teleostei: Chaetodontidae) from Australia


Coradion calendula Matsunuma, Motomura & Seah, 2023

Coradion chrysozonus Cuvier 
(ex. Kuhl & Van Hasselt) in Cuvier & Valenciennes, 1831 

in Matsunuma, Matsumoto, Motomura, Seah & Jaafar, 2023. 

The new butterflyfish, Coradion calendula, is described on the basis of 44 specimens collected off Western Australia, the Northern Territory, and north Queensland, Australia. The new species is most similar to Coradion chrysozonus, with which it shares IX dorsal-fin spines, a single ocellated spot on the soft-rayed portion of the dorsal-fin, and a single dark band on the frontal surface of the thorax. The new species is distinguished from C. chrysozonus by slightly higher ranges of dorsal-fin soft rays 28–32, mode 29 (vs. 27–30, mode 28) and anal-fin soft rays 20–22, mode 21 (vs. 18–21, mode 20); an orange band on the caudal peduncle in fresh specimens (lost after preservation) with a saddle-like blackish dorsal streak (vs. a broad brown -to-black circumpeduncular band in both fresh and preserved specimens); a sharply pointed pelvic fin with an almost straight posterior contour when spread (vs. a rounded pelvic fin with an expanded posterior contour); and a dark band on each interopercle joining on the ventral midline, with their anterior margins forming a sharply pointed “V” in ventral view (vs. separated by a relatively wide interspace). Despite well-defined morphological and coloration differences, the mtDNA difference between the two species was relatively low, 0.8–1.9% (mean 1.3%) and 2.9–7.5% (mean 4.8%) pairwise sequence difference in COI and control region genes, respectively. Morphological and colorpattern characters and mtDNA lineage were not concordant in some specimens from northern Australia, where the two species overlap, suggesting that the two species hybridize at their common biogeographic borders. 

Key words: taxonomy, ichthyology, morphology, coral-reef fishes, mtDNA, biogeography, western Pacific Ocean.

Underwater or aquarium photographs of Coradion chrysozonus (A–E) and Coradion calendula sp. nov. (F).
A: Wagmag Bay, Raja Ampat, Indonesia, by Lesley Clements,; B: Bitung, Sulawesi Utara, Indonesia, by Mark Rosenstein, modified from; C, D: Great Barrier Reef, Australia, by Yi-Kai Tea; E: KAUM-I. 167700, 79.8 mm SL, Arthur Paches, Great Barrier Reef, Australia, by Fenton Walsh;
F: Exmouth, WA, Australia, by Kristin Anderson,

Coradion calendula, sp. nov. Matsunuma, Motomura & Seah 
Orange-tailed Coralfish

Diagnosis. A species of Coradion distinguished from all congeners by a combination of dorsal-fin rays IX, 28–32 (mode 29); anal-fin rays III, 20–22 (mode 21); a single ocellated spot on soft-rayed portion of dorsal fin; no ocellated spot on anal fin; band on caudal peduncle usually orange when fresh (obscured in preserved specimens) with a short, saddle-like, blackish dorsal streak; a sharply pointed pelvic fin with an almost straight posterior contour when spread (most obviously in large specimens >10 cm SL); and a dark band on each interopercle joining on ventral midline with anterior margins forming a sharply pointed “V” in ventral view.

Etymology. The specific name calendula is treated as a noun in apposition, being the generic name of plants in the daisy family Asteraceae (often known as marigolds), alluding to the characteristic orange band on the caudal peduncle of the new species.
Coradion calendula sp. nov. collected by bottom trawl off WA, Australia (specimens not retained). A: vicinity of Bigge Island, Kimberly; B: off Karratha, North West Shelf. ©Chris Dowling.

Photographs of fresh specimens of Coradion calendula sp. nov. (A–C) and C. chrysozonus (D–F).
 A: CSIRO H8224-20, holotype, 87.8 mm SL, Western Australia; B: CSIRO CA3049, paratype, 81.2 mm SL, Western Australia; C: NSMT-P 121516, paratype, 155.9 mm SL, Western Australia;
D: KAUM-I. 56030, 86.9 mm SL, Philippines; E: KAUM-I. 132465, 95.0 mm SL, Singapore; F: KAUM-I. 79809, 110.3 mm SL, Malaysia.
Photos by John Pogonoski (CSIRO) (A), CSIRO (B) and Far Seas Fisheries Research Laboratory, Japan (C).

 M. Matsunuma, T. Matsumoto, H. Motomura, Y.G. Seah and T.N.A.M. Jaafar. 2023. Coradion calendula, A New Butterflyfish from Australia (Teleostei: Chaetodontidae).  Journal of the Ocean Science Foundation. 40,