DNA Taxonomy of Paranemertes (Nemertea: Hoplonemertea) with Spirally Fluted Stylets

Ribbon worms (phylum Nemertea) from Bodega Bay, California: A largely undescribed diversity

The diversity of nemerteans along the Pacific coast of the United States is regarded as well characterized, but there remain many cryptic, undescribed, and "orphan" species (those known only in their larval form). Recent sampling of nemerteans in Oregon and Washington has begun to fill in these taxonomic gaps, but nemertean diversity in California has received relatively little attention over the past 60 years. During the summers of 2019 and 2020, nemertean specimens were collected from 20 locations in the Bodega Bay region of northern California, USA, including rocky intertidal shores, sandy beaches, mudflats, and other habitats. Based on morphological assessment and DNA sequence analysis (partial Cytochrome Oxidase I and 16S rRNA genes), our surveys identified 34 nemertean species. Only 13 of these (38%) can be confidently assigned to described species. Another 11 represent species that are new to science, including members of the genera Riserius, Nipponnemertes, Poseidonemertes, Zygonemertes, Nemertellina, Oerstedia, and three species of uncertain affiliation. The remaining ten species include undescribed or cryptic species of uncertain status that have been found previously along the Pacific Coast of North America. Our surveys also document extensions of known geographic ranges for multiple species, including the first records in California of Antarctonemertesphyllospadicola, Cephalothrixhermaphroditica, and Maculauraoregonensis. This is the first report of the genus Nemertellina in the northeast Pacific and Riserius in California. Overall, our findings highlight how much remains to be learned about the diversity and distribution of nemerteans in the northeast Pacific.

Kulikovia alborostrata and Kulikovia fulva comb. nov. (Nemertea: Heteronemertea) are Sister Species with Prezygotic Isolating Barriers

The heteronemertean Kulikovia alborostrata (Takakura, 1898) was originally described as Lineus alborostratus based on material from Misaki, Japan. Although this species was regarded as consisting of two color variants, purple and brown-yellow, the identity of these variants has never been examined based on topotypes. In this study, we performed a multi-locus phylogeny reconstruction, species delimitation analyses, and cross-fertilization experiments to examine the species status of Takakura's original taxon concept consisting of these color variants. Our results suggest that the purple type is identical to Lineus alborostratus Takakura, 1898 auct. (currently Kulikovia alborostrata), whereas the brown-yellow type is conspecific with Lineus fulvus Iwata, 1954, originally established from Hokkaido. These two species appear to have a sister-taxon relationship and are reproductively isolated from each other by prezygotic mechanisms involving gamete incompatibility, minimally separated with 2.8% (16S rRNA) and 14.4% (COI) uncorrected p-distances. We propose that the purple type be considered as representing the true identity of the nominal species Lineus alborostratus (currently assigned to the genus Kulikovia) to maintain the common usage of the name. Although Takakura's type material is not extant, we consider that neotypification is unnecessary in this case because no taxonomic/nomenclatural confusion persists. We also propose to transfer Lineus fulvus to yield Kulikovia fulva comb. nov.

Redescription of Emplectonema viride - a ubiquitous intertidal hoplonemertean found along the West Coast of North America

Emplectonema viride Stimpson, 1857, a barnacle predator, is one of the most common and conspicuous intertidal nemerteans found along the West Coast of North America from Alaska to California, but it is currently referred to by the wrong name. Briefly described without designation of type material or illustrations, the species was synonymized with the Atlantic look-alike, Emplectonema gracile (Johnston, 1837) by Coe. Here we present morphological and molecular evidence that E. viride is distinct from E. gracile. The two species exhibit differences in color of live specimens and egg size and are clearly differentiated with species delimitation analyses based on sequences of the partial regions of the 16S rRNA and cytochrome c oxidase subunit I genes. In order to improve nomenclatural stability, we re-describe E. viride based on specimens from the southern coast of Oregon and discuss which species should be the type species of the genus. Emplectonema viride was one of the two species originally included in the genus Emplectonema Stimpson, 1857, but subsequent synonymization of E. viride with E. gracile resulted in acceptance of the Atlantic species, E. gracile, as the type species of the genus. We resurrect E. viride Stimpson, 1857 and following Corrêa's designation, this should be the type species of the genus Emplectonema.

Preliminary Report of a Neurokinin-Like Receptor Gene Sequence for the Nemertean Paranemertes sp

Tachykinins (TKs) are a family of neurotransmitters that function as signaling molecules for such processes as maintaining homeostasis, regulating stress response, and modulating pain. TKs require the expression of at least one of three receptor subtypes: Neurokinin Receptor-1 (NKR-1), Neurokinin Receptor-2 (NKR-2), or Neurokinin Receptor-3 (NKR-3). We have isolated and cloned a portion of a gene coding for a tachykinin-like receptor from the nemertean Paranemertes sp. This 488-bp portion contains a short 101-bp segment that shares 85% similarity to the mouse substance-K receptor in Mus musculus and 83% similarity to the moth neuropeptide receptor A24 in Bombyx mori. Translated homology analysis aligning the coding sequence with the initial cytoplasmic carboxyl terminus of numerous G-protein coupled neuropeptide receptors also revealed 73% similarity to B. mori neuropeptide receptor A24. Our finding is the first report of a sequence amplified from Paranemertes sp. that may code for a small portion of a G-protein-coupled neuropeptide receptor with significant similarity to the TKR family, particularly the NKR-3 receptor isoform. This novel finding may open new avenues into exploring the role of tachykinin and its receptor in nemertean neurophysiology.