Revision of the pantropical genus 'Treptopale' (Annelida: Phyllodocida: Chrysopetalidae): Redescription of 'Treptopale rudolphi' Perkins, 1985 and description of two new species including comparison of 'Treptopale' populations in northern Australia

Abstract

The monotypic genus Treptopale, originally described from the Atlantic Ocean, is now extended - with the description of two new species with a broad and almost sympatric distribution - throughout the Indo-Pacific Ocean. The type species, Treptopale rudolphi Perkins, 1985, is redescribed from additional material from the type locality in the Florida Keys, western Atlantic Ocean, and from material examined from the Cape Verde Islands and Cape Town, South Africa. The morphology of the notochaetal lateral paleae group separates the Atlantic Treptopale rudolphi from a cryptic Treptopale species complex that extends from the Seychelles, western Indian Ocean, throughout the western Indo-Pacific to Hawai'i, eastern Pacific Ocean. Morphological analysis of tropical northern Australian populations of the two new Treptopale species, which are typically found among Halimeda algae on coral reefs, revealed two species separated primarily on the shape and insertion point of a transitional lateral palea and a marked difference in the degree of raised ribs of the main paleae: Treptopale homalos sp. nov. is predominantly found along the eastern Queensland coast from Heron Island north to New Guinea; T. paramolos sp. nov. is predominantly found along the Northern Territory coast. The two species occur sympatrically in a number of localities across tropical northern Australia and both are present on offshore and mainland reefs of northern Western Australia. Reproductive and larval states and chaetal patterns within and between species are presented. The two patterns of morphology and diversity present in these taxa, observed also across the Indo-Pacific, are plausibly related to ancient colonisation histories.