Melanotaenia iris, a New Freshwater Rainbowfish (Melanotaeniidae) from Papua New Guinea with Notes on the Fish Fauna in Head Waters

Abstract

A new melanotaeniid rainbowfish, Melanotaenia iris, is described from mountain tributaries of the Strickland River in west-central Papua New Guinea. It is most closely related to M. goldiei of southern New Guinea, but differs in colour pattern, a distinctive high number of scales on the suborbital-preopercle bones, and a greater number of soft dorsal fin rays. Notes are also included on the poorly developed fish fauna of head waters in the Fly-Strickland and Sepik river systems. Most streams thus far investigated have less than 4 species. The plotosid catfish Tandanus equinus appears to be the most successful colonizer of fast-flowing highland streams in the Fly-Strickland system and is sometimes the only species present.