Zoological Studies

Vol. 61, 2022

(update: 2022.11.25)

Morphology, Feeding Rate and Larval Settlement Preference of the Corallivorous Nudibranch Phestilla subodiosa (Nudibranchia: Trinchesiidae) from Hong Kong

Sam King Fung Yiu1 and Jian-Wen Qiu1,*

1Department of Biology and Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Hong Kong Baptist University, Hong Kong, China. *Correspondence: E-mail: qiujw@hkbu.edu.hk (Qiu).
E-mail: 20482205@life.hkbu.edu.hk (Yiu)

Received 3 May 2022 / Accepted 11 August 2022
Communicated by Benny K.K. Chan

We studied the morphology, host specificity, feeding rate and larval settlement preference of the corallivorous nudibranch Phestilla subodiosa collected from the field. These specimens collected from the scleractinian coral Monipora peltiformis in Hong Kong waters are morphologically different from the holotype and paratypes collected from an aquarium culture of Montipora spp., as they have diamondshaped swollen bulbs, and brown spots on cerata, as well as bulbs and the body immediately posterior to cerata. In experiments where P. subodiosa individuals were placed on the surface of several species of common scleractinian corals collected from Hong Kong waters, the nudibranchs were found to feed on M. peltformis at a rate of 0.05 cm2 individual-1 d-1; however, they were killed and eaten by other tested coral species (Pavnoa decussata, Porites lutea and Duncanopsammia peltata). When cultured in seawater conditioned with M. peltiformis, the veliger larvae required six days to become competent for settlement, and at day 9 could reach a maximum metamorphic rate of 31.1%. At competence, the veliger larvae could
be induced to settle, indicating the presence of a larval settlement cue released by the host coral. Other coral species or their conditioned seawater did not induce settlement of the P. subodiosa larvae. Overall, our study expands the distribution record of P. subodiosa, adds this species to the list of corallivorous nudibranchs in Hong Kong waters, provides morphological features that were not included in the original
description of this species, reveals the host specificity, and provides the feeding rate of this species. These results contribute to a better understanding of the diversity and potential impact of corallivorous nudibranchs in coral ecosystems.

Key words: Coral health, Corallivory, Montipora, Phestilla, Predation, Subtropical Reef.

Citation: Yiu SKF, Qiu JW. 2022. Morphology, feeding rate and larval settlement preference of the corallivorous nudibranch Phestilla subodiosa (Nudibranchia: Trinchesiidae) from Hong Kong. Zool Stud 61:59. doi:10.6620/ZS.2022.61-59.

Supplementary materials: Table S1 | Table S2 | Table S3 | Table S4 | Table S5 | Table S6