Vol. 63, 2024
Morphology and Phylogenetic
Position of Sargassum Nudibranch Scyllaea
fulva Quoy & Gaimard, 1824 (Nudibranchia: Scyllaediae):
First Record in Hong Kong
Sam
King Fung Yiu1,2,*, Thomas Ka Tung Leung2, Gabriel Yeung Lee2, and Meng Yan2,*
doi:10.6620/ZS.2024.63-04
1School
of Biological Science, The University of Hong Kong, Hong Kong, China.
*Correspondence: E-mail: cyclesamyiu@hotmail.com (Yiu)
2State Key Laboratory of Marine Pollution, City
University of Hong Kong, Hong Kong, China. *Correspondence: E-mail:
mengyan@cityu.edu.hk (Yan)
E-mail: thomas1126199716@gmail.com (Leung);
auytfff1357924680@gmail.com (Lee)
(Received 13 July 2023 /
Accepted 27 December 2023 / Published -- 2024)
Communicated by James D. Reimer
Scyllaeidae is a small group of
nudibranchs comprising three genera (Scyllaea,
Notobryon, and Crosslandia) with striking
morphological similarities, making their identification challenging
based on external features alone. Previous studies have highlighted the
significance of central radular teeth in distinguishing Notobryon from Scyllaea and Crosslandia. The genus Scyllaea, commonly known as the
sargassum nudibranch, currently consists of only two valid species, Scyllaea pelagica and Scyllaea fulva. These species inhabit seaweed Sargassum spp., feeding on hydroids. During a biodiversity survey conducted in April 2023, seven sargassum nudibranch individuals were collected from the seaweed Sargassum spp. at a depth of 2 meters in Tai She Wan through SCUBA diving. Initially, the
specimens were misidentified based on their resemblance to Notobryon
wardi and previous local records. However, thorough morphological and
molecular examinations confirmed them to be Scyllaea fulva, representing the
first record of this species in Hong Kong. Notably, our specimens
lacked the blue spots observed in specimens from Thailand and the West
Pacific Ocean, as reported in previous studies. Internally, a
pineapple-like structure formed a honeycomb pattern on the surface of
the masticatory edge of the jaw flap, with the presence of central
radular teeth. A Maximum Likelihood tree analysis revealed Crosslandia to be the sister group
of Scyllaea. Comparative
analysis of intra-specific distances between individuals from the
Philippines, French Polynesia, and Hong Kong indicated a close
relationship between the Hong Kong specimens and those from the
Philippines. Furthermore, we provide a detailed description of the
external and internal morphology of Scyllaea
fulva in this paper, integrating valuable morphological
information for future species identification purposes.
Key words: Scyllaeidae, Sea slug, Mollusc,
Subtropical reef, South China Sea
Citation: Yiu SKF, Leung TKT, Lee GY, Yan
M. 2024. Morphology and phylogenetic position of sargassum Nudibranch Scyllaea fulva Quoy & Gaimard,
1824 (Nudibranchia: Scyllaediae): first record in Hong Kong. Zool Stud 63:04. doi:10.6620/ZS.2024.63-04.
Supplementary
materials: Table S1丨Table S2丨Table S3丨Table S4
|