Despite the advances in phylogenetic systematics of invertebrates, the taxonomic literature continues to be plagued by references to ‘archaic’ taxa, possessing what are thought to be ‘primitive’ features. Such is the case for the palaeonemertean genus Carinina, often referred to as the most archaic nemertean taxon because of the superficial position of its nervous system. Here we describe two new species of Carinina from the north-east Pacific and the Sea of Japan, and present a phylogeny of the class Palaeonemertea based on the sequences of five gene regions, which suggests that Carinina is no more basal than any other genus of palaeonemerteans, and that its basiepithelial nervous system is likely a derived rather than an ancestral state for the phylum.

The genus Telestula includes 12 valid species, which occur in deep waters and are rarely reported. Here we compare colonies of Telestula humilis collected off Spain with type material and morphologically closely related genera. Our phylogenetic analyses based on both complete mitogenomes, and partial mitochondrial and nuclear rRNA genes recovered Telestula humilis sister to Incrustatus and Inconstantia rather than Telestula. This result, together with the morphological observations, supports the taxonomic reassignment of Telestula humilis to Pseudotelestula gen. nov. as Pseudotelestula humilis comb. nov.

Golden corals are conspicuous components in deep-sea gorgonian assemblages. Although common, their taxonomy still conflicts with evolutionary histories. Herein, based on molecular data and morphological examination, we create a new genus, Ramuligorgia, to accommodate Pleurogorgia militaris, redescribing it as Ramuligorgia militaris comb. nov. Additionally, we describe Aurogorgia tasmaniensis gen. nov. et sp. nov., including it and the type species, Pleurogorgia plana, within Pleurogorgiidae fam. nov.

Appearances can deceive; through genetic analysis we can discover that, what was once one species, is rather a complex of cryptic species. The globally introduced species Styela canopus was suspected to be just such an example. We found that, indeed, it is a complex of many cryptic species, often with more than one clade found in sympatry. With several lineages already introduced around the world, we must quickly understand the unique biology of each lineage along with their invasive potential.

This study describes three new species and analyses their relationships within a Neotropical genus of land flatworms. Two of them show distinctive colour patterns, contrasting yellow and black, which is unusual in species of the genus. We discuss some morphological knowledge gaps in Obama, as well as issues regarding analyses based on molecular markers, which should be addressed to clarify relationships within the genus.

Among ~1300 species of world nemerteans, seven species in five genera of lineid heteronemerteans have been known to possess a branched proboscis. In this paper, we describe the eighth branched-proboscis species: Gorgonorhynchus citrinus sp. nov. from Okinawa, Japan. We infer the phylogenetic relationships between the genus and other members of Lineidae along with newly sequenced data of another branched-proboscis heteronemertean, Polydendrorhynchus zhanjiangensis (Yin & Zheng, 1984) from China.