A New Species of Predatory Nudibranch (Gastropoda: Trinchesiidae) of the Coral Pavona decussata

Underwater Impact and Intention-Behaviour Gap of Scuba Divers on Coral Communities in Hong Kong SAR, China

Recreational diving, under the continual growth of the scuba diving industry, may escalate coral reef damage as one of the substantial anthropogenic impacts and is of pressing concern. Besides unregulated and excessive diving activities, accidental contact with corals by inexperienced divers can cause recurring physical damage and heighten the pressure on coral communities. Understanding the ecological impacts of underwater contact with marine biota will thus be crucial to develop more sustainable scuba diving practices in Hong Kong. To probe the scuba diving impacts of divers' contact with coral communities, WWF-Hong Kong started a citizen science monitoring programme and invited 52 advanced divers to conduct direct underwater observations. Questionnaires were also developed to examine and address the research gap between the associated attitudes and the perceived contact rate of divers. Results from analysing the underwater behaviours of 102 recreational divers showed inconsistent perceived and actual contact rates. It was revealed that recreational divers might often overlook the ecological effects of their activities underwater on coral communities. The questionnaire findings will be utilised to improve the framework of the dive-training programmes and enhance divers' awareness to minimise their influence on the marine environment.

Three New Species of the Sun Coral Genus Tubastraea (Scleractinia: Dendrophylliidae) from Hong Kong, China

Tubastraea is a genus of azooxanthellate scleractinian corals belonging to the family Dendrophylliidae, which are commonly called sun corals. This genus currently has only seven recognized species. In this paper, we report three new species of Tubastraea, including T. dendroida sp. nov., which has a tree-like colony, T. violacea sp. nov., which has violet polyps, and T. chloromura sp. nov., which has olive green polyps. These species are distinct in their septal structures, as well as their rDNA sequences including the entire ITS1, 5.8S and ITS2, and a segment of the 18S and 28S genes.

An Updated Checklist of Sea Slugs (Gastropoda, Heterobranchia) from Hong Kong Supported by Citizen Science

Research on heterobranch sea slug diversity in Hong Kong was flourishing in the 1980-90s, with the first checklist and guidebook published and many new species and records documented later. This golden era of sea slug research ended abruptly, and no review nor any extensive collection has been done in the past 20+ years. In view of the extensive revision in heterobranch systematics in recent years, the current checklist can be considered out of date in both nomenclature and composition. Therefore, we are dedicated to providing a synthesis of the current state of knowledge on Hong Kong sea slug diversity by reviewing previous records and engagement of citizen science. An integration of previously published and unpublished records revealed the presence of 186 species, of which 107 species were documented by our citizen science programme with a further report of 71 new records. This yields a total of 257 species from 126 genera, 53 families and ten higher taxa, of which seven species have not been reported elsewhere from Hong Kong. While the present study has markedly illuminated our understanding of sea slug diversity in Hong Kong, the true biodiversity may be underestimated given the high proportion of novel records, especially when many previous records were not herein observed. Hong Kong likely harbours a greater sea slug diversity which awaits discovery from more rigorous sampling and a more inclusive citizen science programme.

An updated inventory of sea slugs from Koh Tao, Thailand, with notes on their ecology and a dramatic biodiversity increase for Thai waters

Improved access to field survey infrastructure throughout South-East Asia has allowed for a greater intensity of biodiversity surveys than ever before. The rocky bottoms and coral reef habitats across the region have been shown to support some of the highest sea slug biodiversity on the planet, with ever increasing records. During the past ten years, intensive SCUBA surveys have been carried out at Koh Tao, in the Gulf of Thailand, which have yielded remarkable findings in sea slug biology and ecology. In this work a brief history of sea slug biodiversity research from Thailand is covered and a complete inventory of sea slugs from Koh Tao, Gulf of Thailand is provided. This inventory is based on surveys from 2012 to 2020, with previously unreported findings since 2016. Habitat specificity and species-specific ecology are reported where available with a focused comparison of coral reef habitats and deeper soft-sediment habitats. The findings contribute 90 new species records for Thai waters (92 for the Gulf of Thailand) and report a remarkable consistency in the proportional diversity found to be exclusive to one habitat type or another. Additionally, taxonomic remarks are provided for species documented from Koh Tao that have not been discussed in past literature from Thailand, and a summary of previous records in the Indo-West Pacific is given.

A New Species of Predatory Nudibranch (Gastropoda: Trinchesiidae) of the Scleractinian Coral Goniopora

Members of the nudibranch genus Phestilla are common predators of scleractinian corals, but currently this genus has 10 described species only. Here we describe Phestilla goniophaga sp. nov., the first formally named predatory nudibranch species of the stony corals from the genus Goniopora. The new species can be distinguished from its congeneric species by the large number of long cerata (up to 16 rows and 23 cerata per row), and white rounded hump on the notum. The hump resembles the mouth of the coral poly, while the cerata resemble the coral tentacles. The egg masses of P. goniophaga sp. nov. are unique among Phestilla spp. egg masses in being bright orange in color, and forming a coiled ribbon. Analysis of the COI, 16S rRNA and H3 genes of P. goniophaga sp. nov. also showed that this species is distinct from other congeneric species.