PTEROBDELLA OCCIDENTALIS N. SP. (HIRUDINIDA: PISCICOLIDAE) FOR P. ABDITOVESICULATA (MOORE, 1952) FROM THE LONGJAW MUDSUCKER, GILLICHTHYS MIRABILIS, AND STAGHORN SCULPIN, LEPTOCOTTUS ARMATUS, AND OTHER FISHES IN THE EASTERN PACIFIC.

Pterobdella occidentalis n. sp. (Hirudinida: Piscicolidae) is described from the longjaw mudsucker, Gillichthys mirabilis Cooper, 1864, and the staghorn sculpin, Leptocottus armatus Girard, 1854, in the eastern Pacific, and the diagnosis of Pterobdella abditovesiculata (Moore, 1952) from the 'o'opu 'akupa, Eleotris sandwicensis Vaillant and Sauvage, 1875, from Hawaii is amended. The morphology of both species conforms with the genus Pterobdella in possessing a spacious coelom, well-developed nephridial system, and 2 pairs of mycetomes. Originally described as Aestabdella abditovesiculata, P. occidentalis (present along the U.S. Pacific Coast), can be distinguished from most congeners by its metameric pigmentation pattern and diffuse pigmentation on the caudal sucker. Based on mitochondrial gene sequences, including cytochrome c oxidase subunit I (COI) and NADH dehydrogenase subunit I (ND1), P. occidentalis forms a distinct polyphyletic clade with Pterobdella leiostomi from the western Atlantic. Based on COI, ND1, and the 18S rRNA genes, other leech species most closely related to P. occidentalis include Pterobdella arugamensis from Iran, Malaysia, and possibly Borneo, which likely represent distinct species, and Pterobdella abditovesiculata from Hawaii, one of only a few endemic fish parasites in Hawaii. Like P. abditovesiculata, P. arugamensis, and Petrobdella amara, P. occidentalis is often found in estuarine environments, frequently infecting hosts adapted to a wide range of salinity, temperature, and oxygen. The physiological plasticity of P. occidentalis and the longjaw mudsucker host, and the ease of raising P. occidentalis in the lab, make it an excellent candidate for the study of leech physiology, behavior, and possible bacterial symbionts.

Primary Microbial Succession in the Anchialine Ecosystem.

When new land is created, initial microbial colonization lays the foundation for further ecological succession of plant and animal communities. Primary microbial succession of new aquatic habitats formed during volcanic activity has received little attention. The anchialine ecosystem, which includes coastal ponds in young lava flows, offers an opportunity to examine this process. Here, we characterized microbial communities of anchialine habitats in Hawaii that were created during volcanic eruptions in 2018. Benthic samples from three habitats were collected ∼2 years after their formation and at later time points spanning ∼1 year. Sequence profiling (16S and 18S) of prokaryotic and eukaryotic communities was used to test whether communities were similar to those from older, established anchialine habitats, and if community structure changed over time. Results show that microbial communities from the new habitats were unlike any from established anchialine microbial communities, having higher proportions of Planctomycetota and Chloroflexi but lower proportions of green algae. Each new habitat also harbored its own unique community relative to other habitats. While community composition in each habitat underwent statistically significant changes over time, they remained distinctive from established anchialine habitats. New habitats also had highly elevated temperatures compared to other habitats. These results suggest that idiosyncratic microbial consortia form during early succession of Hawaiian anchialine habitats. Future monitoring will reveal whether the early communities described here remain stable after temperatures decline and macro-organisms become more abundant, or if microbial communities will continue to change and eventually resemble those of established habitats. This work is a key first step in examining primary volcanic succession in aquatic habitats and suggests young anchialine habitats may warrant special conservation status.