We describe a new species of marine flatworm, Notoplana antipatharicola sp. nov., which is associated with a black coral species of the genus Myriopathes Opresko, 2001 from Sugashima Island in Mie Prefecture, Japan. This is the second known example of a polyclad species associated with black corals; the first was Anthoplana antipathellae Bo Betti, 2019 inhabiting Antipathella subpinnata (Ellis Solander, 1786) from the mesophotic Atlantic-Mediterranean Sea. Notoplana antipatharicola sp. nov. can be distinguished from the other known congeners primarily by its short pharynx, which is positioned in the anterior body, and few or no cerebral eyespots. We conducted molecular phylogenetic analyses using two concatenated datasets of (i) partial sequences from four gene markers (18S rRNA, 28S rRNA, 16S rRNA, and cytochrome c oxidase subunit I) and (ii) the whole mitogenome. The four-marker phylogeny inferred the new species to be sister to a clade comprising both free-living and mollusk-associated species within the superfamily Leptoplanoidea. This suggests that the black coral-associated lifestyle may have evolved independently of the symbiotic lifestyle with mollusks in this lineage, but further examination with denser taxon sampling is still required.
This paper evaluates the ichthyoplankton communities in the deep waters of the Southern Gulf of Mexico during summer, focusing on the influence of hydrodynamics on their distribution. High-resolution hydrographic data and zooplankton samples were collected from 63 stations during a multidisciplinary research cruise in June 2015. Ichthyoplankton organisms were isolated from the samples, identified to the species level, and subsequently analyzed in relation to local hydrodynamic features. The data revealed a dynamic environment shaped by a cyclonic eddy that generated strong gradients in temperature, salinity, and density. The ichthyoplankton community comprised 183 species belonging to 67 families and 29 orders. The most abundant species were Notolychnus valdiviae, Bregmaceros cantori, Diogenichthys atlanticus, and Syacium papillosum, with abundances of 109.6, 85.6, 68.1, and 52.0 ind 100 m−3, respectively. Conversely, species such as Neoscopelus macrolepidotus, Zu cristatus, and Heteropriacanthus cruentatus occurred in low numbers (0.4 ind 100 m−3). Circulation patterns significantly influenced the horizontal distribution of the dominant species, resulting in high abundance values near the eddy center and periphery. However, localized processes, such as coastal dynamics, shelf-break interactions, and distinct low-salinity freshwater signatures, also played a critical role in shaping spatial distribution patterns. Furthermore, comparisons of species abundance between day and night revealed notable shifts, suggesting active diel vertical migrations during the sampling period. Ultimately, these findings advance our understanding of ichthyoplankton community dynamics, highlighting the fundamental role of physical-biological coupling in the deep Gulf of Mexico.
Molecular analyses confirmed the identification of rhizocephalan barnacles that infect the coastal crabs of the genus Hemigrapsus (Varunidae) in Peter the Great Bay of the Sea of Japan. Polyascus polygeneus (Lützen Takahashi, 1997) is the common parasite of Hemigrapsus sanguineus (De Haan, 1835). Parasacculina yatsui (Boschma, 1936) apparently occurs less frequently, it was found on two of the 21 infected crabs. These rhizocephalans are very similar in external morphology. Both belong to the family Polyascidae and have globular receptacles located outside the visceral sac, hence they cannot be distinguished by this feature. However, these species differ clearly in the structure of the external cuticle: it is smooth in P. polygeneus, but covered with numerous hyaline spines in P. yatsui. The morphology of their larvae also differs markedly. In Peter the Great Bay, P. polygeneus was also found on the second coastal crab, H. takanoi Asakura Watanabe, 2005. Previously, this parasite was noted on H. longitarsis (Miers, 1879). At present, Peter the Great Bay is probably the most northern area of distribution of P. polygeneus and P. yatsui.
Effective conservation of marine biodiversity requires a strong understanding of how marine systems change over time. Connections between coastal benthic and pelagic systems mean that additional insight may be gained from surveying both habitats alongside each other to investigate if interannual trends are similar. We utilised a multiyear dataset of both seabed and midwater baited remote underwater video systems (BRUVS) deployments from the Shark Bay World Heritage Area to investigate interannual changes in broad metrics of abundance, richness, biomass, and length, as well as composition for neighbouring pelagic and demersal communities. In total, 297 taxa were recorded, 272 from seabed surveys and 47 from midwater surveys. Between four surveys across a 5-year period, patterns in benthic and pelagic habitats differed, but both showed significant shifts in community composition between each survey. Benthic communities were broadly stable in biomass, fork length, and abundance. Pelagic communities increasingly favoured larger abundances of smaller fishes which may be indicative of excessive fishing pressure. Several vulnerable species were recorded including multiple young of the month shortfin mako sharks (Isurus oxyrinchus). The Shark Bay World Heritage Area was found to be an area of high biodiversity undergoing significant interannual change in both its pelagic and demersal communities, which should inform current and future conservation approaches.
A new species of echinoderid kinorhynchs, Echinoderes dimorphus sp. nov. collected from oxidized brown mud in the northwestern part of the Sea of Japan, Northwestern Pacific, is described and illustrated using light (LM) and scanning electron (SEM) microscopy, and DNA sequences from the mitochondrial cytochrome c oxidase subunit 1 (COI) gene. This new representative of the most diverse kinorhynch genus is characterized by its unique arrangement and morphology of spines, tubes, glandular cell outlets and cuticular plate composition, thus being distinguished from other congeners. Glandular cell outlets type 2 are present in subdorsal, laterodorsal, sublateral and ventrolateral positions on trunk segment 2, in subdorsal position on trunk segment 4, in midlateral position on trunk segment 5, and in sublateral position on trunk segment 8. Trunk segment 2 has a midventral fissure; trunk segment 11 with middorsal protuberance and at least partially subdivided tergal plate; tergal extension with long subterminal seta. This species is well recognized by the presence of sexual dimorphism remarkably expressed in the length and shape of lateral terminal spines. Females have very short and stout lateral terminal spines, while males possess very long lateral terminal spines with a thin and flexible distal portion about three times longer than those in females.
