Marine biologists from Hong Kong Baptist University (HKBU) have identified two new soft coral species, Parasphaerasclera dimorpha sp. nov. and Paraminabea inflata sp. nov, from the urban waters of Hong Kong Special Administrative Region and Zhuhai. With these additions, the number of known species in their respective genus, Parasphaerasclera and Paraminabea, has increased to 11, with Parasphaerasclera dimorpha sp. nov. being the first of its kind reported from the China Seas.
New soft corals species: Parasphaerasclera dimorpha sp. nov. Photo source: HKBU
Soft coral taxonomy is challenging because different species can closely resemble one another in appearance, and genetic data are limited. In the China Seas, only four digitate or lobate soft coral species in the genus Paraminabea had been documented before this study.
Click to Gallery
New soft corals species: Parasphaerasclera dimorpha sp. nov. Photo source: HKBU
A colony of Parasphaerasclera dimorpha sp. nov. with extended tentacles. Photo source: HKBU
New soft coral species Paraminabea inflata sp. nov. in the field. Photo source: HKBU
New soft coral species Paraminabea inflata sp. nov. in laboratory. Photo source: HKBU
A research team led by Professor Qiu Jianwen (left), with members including Dr Li Yixuan, Post-doctoral Research Fellow (middle) and Loke Haixin, PhD student (right) of the Department of Biology at HKBU, discovered two new species of soft corals, Parasphaerasclera dimorpha sp. nov. and Paraminabea inflata sp. nov., from the waters of Hong Kong and Zhuhai respectively. Photo source: HKBU
Professor Qiu Jianwen, Professor of the Department of Biology at HKBU, who led the research team, said, “The study expands what we know about soft coral diversity in the Guangdong-Hong Kong-Macao Greater Bay Area. It also shows that even in urbanised waters, significant cryptic biodiversity remains to be documented and protected.”
Since 2023, Professor Qiu’s team has collected eight coral colonies at about 15 to 25 metres depth from the rocky reefs off Hong Kong’s Sung Kong Island and Zhuhai’s Heizhou Island. Among these colonies, they have identified two new species, Parasphaerasclera dimorpha sp. nov. and Paraminabea inflata sp. nov., for the first time worldwide.
Parasphaerasclera dimorpha sp. nov. was discovered in the waters off Hong Kong’s Sung Kong Island. It displays bright orange-red colour and forms colonies that are digitiform in shape with a conspicuous stalk and branches. Usually found scattered on boulders with other coral species, it is characterised by the presence of stalk sclerites including spindle-shaped elements such as rare tuberculated spindles. This marks the first discovery of a Parasphaerasclera species in Hong Kong.
A colony of Parasphaerasclera dimorpha sp. nov. with extended tentacles. Photo source: HKBU
Paraminabea inflata sp. nov. is found in the waters of both Hong Kong and Zhuhai. It is the third Paraminabea species discovered in Hong Kong over the past 15 years. Attached to the rock surfaces in the sea, it forms colonies that are yellow or orange in colour with long polyps. It has unique sclerites including tuberculated spheroids, and was misidentified in the past as another coral species.
New soft coral species Paraminabea inflata sp. nov. in the field. Photo source: HKBU
The HKBU research team identified these two new coral species using integrative taxonomy, an approach that combines morphological and genetic data for species delimitation. They worked out the DNA sequencing of the species and clarified their evolutionary relationships: Parasphaerasclera dimorpha sp. nov. is sister to an Australian coral species while Paraminabea inflata sp. nov. is sister to a Hong Kong local species. Their genetic and morphological distinctions from these sister species justify the recognition of these new species.
New soft coral species Paraminabea inflata sp. nov. in laboratory. Photo source: HKBU
In addition, the team also assembled the mitochondrial genomes (mitochondrion is an essential organelle found in cells which generates chemical energy to support cell activities) of the two new species, as well as another species of digitate soft coral (Paraminabea rubeusa) discovered in Hong Kong, providing genetic data to calculate the genetic distances of soft corals. Professor Qiu said, “Our research highlights the value of integrative taxonomy in identifying soft corals with similar appearance and provides new mitochondrial genomic resources to advance their taxonomy in the Indo-Pacific.”
Led by Professor Qiu, members of the research team include Dr Li Yixuan, Post-doctoral Research Fellow; Loke Haixin, PhD student; Janice Ng Wing-yan, undergraduate student of the Department of Biology at HKBU; and Professor Liu Lan, Professor of the School of Marine Sciences at Sun Yat‑sen University. The research findings have been published in the international journal Ecology and Evolution.
A research team led by Professor Qiu Jianwen (left), with members including Dr Li Yixuan, Post-doctoral Research Fellow (middle) and Loke Haixin, PhD student (right) of the Department of Biology at HKBU, discovered two new species of soft corals, Parasphaerasclera dimorpha sp. nov. and Paraminabea inflata sp. nov., from the waters of Hong Kong and Zhuhai respectively. Photo source: HKBU
Corals are commonly divided into hard corals and soft corals. Hard corals have received more attention because they build reefs, which are essential for marine habitats and are highly sensitive to environmental threats. A total of 90 hard coral species have been recorded in Hong Kong. Soft corals are flexible, do not build reefs, and often thrive in habitats unsuitable for hard corals. Prior surveys found only 29 species in Hong Kong, with limited genetic data available.
