Johnius javaensis, a new species of croaker (Acanthuriformes, Sciaenidae) from the southern coast of Java, Indonesia

In this study, we describe a newly recognized croaker (Sciaenidae), Johnius javaensis sp. nov. based on five specimens (87–121 mm in standard length) from the southern coast of Java, Indonesia. Specifically, taxonomic reassessment of sciaenids collected from fish markets on the islands of Java, Bali, and Lombok of Indonesia has revealed that specimens previously identified as Johnius heterolepis represent this new species.

Johnius javaensis sp. nov. is characterized by five vesicular mental barbels on the chin, 30–32 dorsal-fin rays, seven or eight scale rows below the lateral line; 11 or 12 lower gill rakers, 11 or 12 swim-bladder appendages, and ventral margin of the sagitta head expanded into a distinct convexity. Historically, four Johnius species (J. amblycephalus, J. fuscolineatus, J. macropterus and J. mannarensis) were reported to have one mental barbel on the chin.

The new species is readily distinguished from all other 33 described Johnius species by possessing five vesicular mental barbels on the chin. A phylogenetic analysis of 21 Johnius species based on the 521 - bp COI gene confirms that the new species is placed as a sister species of J. macropterus, based on an average of dissimilarity 8.16 %.