We report the presence of the coral-killing sponge species Chalinula nematifera (de Laubenfels, 1954) in southern Japan via photographic records and specimens. The species appears to be a substrate generalist on scleractinians and occasionally octocorals, and is found across a wide variety of depths (0 to 24 m), as has been recently reported for this species from Indonesia. From our information, the species is found in southern Japan across the southern and central Ryukyu Islands, with a northern limit of Amami-Oshima Island, although future work will likely expand the range. As our records stretch back more than 20 years, we do not believe Chalinula nematifera is a recent arrival to the region. Due to the potential for this species to harm coral reefs, we suggest field surveys are needed to establish a baseline distribution and abundance database to aid in future monitoring.
We present the complete genome sequences of 13 species of the zoantharian suborder Brachycnemina (Haddon, and Shackleton, 1891; Poliseno et al., 2020). Genome sequencing was performed on genetic material from single wild-collected individuals. For each species the sequence reads were assembled using a de novo method followed by a finishing step. The raw and assembled data are publicly available via GenBank.
Species of the genus Peronia Fleming, 1822, are air-breathing onchidiid sea slugs that inhabit intertidal reef flats of temperate to tropical zones. In the Ryukyu Islands of southern subtropical Japan, Peronia species are a traditional food source for local people. To date, there have been three species recorded around Okinawajima Island; P. verruculata and P. peronii, along with recently described P. okinawensis, which was described as possibly endemic to Okinawajima Island. This study aimed to map the distribution ranges of these three Peronia species within the Ryukyu Islands using molecular analyses in order to understand the specific distribution of each species. Since Peronia species are generally indistinguishable by gross external morphology, a DNA barcoding approach was employed to identify specimens. The molecular data showed that there are four species present in the Ryukyu Islands. P. verruculata (unit #1 sensu Dayrat et al., 2020) was dominant at almost all locations, while P. peronii was present in much lower numbers than P. verruculata, but found across a relatively wide range in the Ryukyu Islands. We newly record P. okinawensis and P. setoensis from Amami Oshima Island and from several places around Okinawajima Island, and also identified high levels of genetic variation within P. setoensis. Peronia okinawensis and P. setoensis have been thought to be endemic to Okinawajima Island and to Honshu, mainland Japan, respectively. However, as both species were observed around Okinawajima and Amami Oshima islands, other islands of the Ryukyus are also likely to harbor these species, and their distribution ranges are wider than previously thought. Based on the results from molecular analyses, we provide general descriptions of each species. Sizes of specimens were consistently smaller for P. setoensis and relatively larger for P. peronii specimens. On the other hand, P. verruculata and P. okinawensis had similar size ranges, but P. okinawensis had comparatively much more distinct papillae. This study revealed that the Ryukyu Islands are the only region currently known with four sympatric Peronia species, and this work provides a basis for future research on these Peronia species throughout the northwest Pacific Ocean, representing the first step in more effective management of the local Peronia fisheries in the Ryukyu Islands.
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