Two new species of Aricidea (Aricidea) (Annelida: Paraonidae) from the Andaman coast and the Gulf of Thailand

Abstract

Two new species of Paraonidae, Aricidea (Aricidea) pacharaphoni sp. nov., and A. (A.) sathingpra sp. nov., are described from the Southwestern Pacific. Aricidea (A.) pacharaphoni sp. nov., collected in the Andaman Coast and the Gulf of Thailand, is clearly distinguished from other species of Aricidea (Aricidea) by having an elongate, faintly annulated median antenna extending to chaetigers 3–7; chaetiger 3 with distinctive globose notopodial postchaetal lobes with long digitiform terminal tips; two types of branchiae, strap-like and foliaceous; and two types of modified neurochaetae, pseudocompound and stout acicular. Aricidea (A.) sathingpra sp. nov., was collected in the Gulf of Thailand and belongs to the articulated antenna group, being separated from all other species of this subgenus by having a triarticulated antenna; pair of distinctive round furrow protuberances on the prostomium; and 6–7 pairs of wide foliaceous branchiae. We suggested that the modification and shape of the notopodial postchaetal lobes in chaetiger 3 are an important morphological character to differentiate the species of this subgenus. Molecular phylogenetic and genetic distance analyses, based on cytochrome oxidase subunit I (COI) gene sequences support the recognition of Aricidea (A.) pacharaphoni sp. nov., as a distinct species. A taxonomic key for all world species of Aricidea (Aricidea) is included.