Sunday 22 December 2019

Photolateralis polyfenestrus: A new species of Ponyfish from the Gulf of Oman.

Ponyfish, Leiognathidae, are small, silvery, laterally compressed Perciforme Fish found in brackish and marine waters around the Indian and western Pacific oceans. Like many Perciformes they have locking spines on their fins, which serve as a defence against predators; locking these spines may not deter the predator from swallowing a Ponyfish, but stand a significant chance of causing the Ponyfish to lodge in the predator's throat and choking the predator. Ponyfish also possess a second defence not found in other Perch, in the form of light organs on their underside which host bioluminscent Bacteria, helping to camouflage them against the sky when seen from below.

In a paper published in the American Museum Novitates on 19 June 2019, John Sparks of the Department of Ichthyology at the American Museum of Natural History, and Prosanta Chakrabarty of the Museum of Natural Science at Louisiana State University, describe a new species of Ponyfish from the Gulf of Oman.

The new species is placed in the genus Photolateralis, on the basis of a translucent midlateral flank stripe, which is unique to this genus, and given the specific name polyfenestrus, meaning 'many windows', in reference to the translucent midlateral windows, which are rounded and appearing spotlike. The species is known only from a single specimen acquired at Mutrah Fish Market in northeastern Oman. This specimen is male, 66.8 mm in length, with two rows of teeth on both the upper and lower jaws. It is is distinguished from congeners by the presence of a short, composite midlateral stripe comprised of three small, rounded translucent windows that are peppered with chromatophores (colour cells).

Photolateralis polyfenestrus, male, 66.8 mm; Gulf of Oman, Mutrah Fish Market. Specimen has a field tag on posterior flank and anteriormost midlateral window is obscured behind pectoral-fin rays in image. Sparks & Chakrabarty (2019).

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