Chromis torquata, A Distinctive New Damselfish From Mauritius

Chromis torquata, from Réunion. Credit: zsispeo

 
With its piercing orange eyes and a bold “collar” behind the head, the newly described Chromis torquata is a relatively easy fish to identify, which makes its a bit surprising that it took so long to get recognized. The species has even been exported into the aquarium trade, but such specimens have invariably been mistaken for its close relative, the Doublebar Chromis (Chromis opercularis). The two species are, however, easily told apart. The eyes of C. torquata have a bright orange iris, while those of C. opercularis (and the closely related C. xanthura and C. anadema) are mostly dark, with only a thin yellow ring surrounding the pupil. The Doublebar Chromis is named for the pair of dark bars edging the operculum and preoperculum, but the preopurcular bar is largely absent in C. torquata, while the opercular bar is dramatically thickened. Juveniles, as is typical for this group, have yellow margins to the posterior fins, contrasting against a bluish body. 

Juvenile Chromis torquata from Mauritius. Credit: DeJong Marinelife

 
This new species is described from Mauritius in the Indian Ocean, but photos also show it to be present at nearby Réunion. Elsewhere in the Indian Ocean, it appears to be replaced by C. opercularis, while C. xanthura and the recently named C. anadema occur in the Pacific. The unusual epithet of this fish derives from the Latin torquatus, meaning “adorned with a necklace or collar”, in obvious reference to the dark bar. 

Chromis torquata, from Réunion. Credit: zsispeo

• Allen, G.R. (2018): Chromis torquata, a new species of damselfish (Pomacentridae) from Mauritius and Réunion. aqua, International Journal of Ichthyology, 24 (1): 15-22.

Joe is classically trained in the zoological arts and sciences, with a particular focus on the esoterica of invertebrate taxonomy and evolution. He’s written for several aquarium publications and for many years lorded over the marinelife at Chicago’s venerable Old Town Aquarium. He currently studies prairie insect ecology at the Field Museum of Natural History and fish phylogenetics at the University of Chicago.