Abstract:

Aim: Intertidal crabs represent significant ecological groups within the nearshore zoobenthic biota. The northern South China Sea is rich in intertidal crabs, but the research progress varies considerably across different regions. Compared with eastern Guangdong, Beibu Gulf, and Hainan Island, our understanding of the intertidal crab fauna in western Guangdong remains relatively limited. To bridge this knowledge gap, it is crucial to explore the intertidal crab fauna on Donghai Island and Naozhou Island, located on eastern side of the Leizhou Peninsula. These islands play a vital role in unveiling the nearshore zoobenthic biogeography of western Guangdong and the northern South China Sea. In this study, we present the findings of a comprehensive field survey and incorporate previous studies to report on the species diversity and distribution patterns of intertidal crabs from these two islands.

Method: During the period of 2021-2022, intertidal crabs were collected from 22 sampling sites located Donghai Island and Naozhou Island. And the taxon recorded in previous studies were revised by literature review. A comprehensive and current checklist of intertidal crabs in the two islands was conducted, and an analysis was conducted to determine the distribution patterns of each species along the coasts of the China seas.

Results: A total of 91 species of brachyuran crabs were collected, representing 26 families and 62 genera during the field survey. Within this collection, 52 species were previously undocumented in the study area. The updated checklist now encompasses 150 intertidal crab species, originating from 33 families and 91 genera. Out of them, 108 species (72.0%) are characterized as the tropical and/or subtropical, with their distribution spanning from the northern South China Sea to the Taiwan Strait or the East China Sea. The remaining 42 species (28.0%) are considered widespread, with each of them being found across from the northern South China Sea to the Yellow and Bohai seas. The intertidal brachyuran fauna of the study area is tightly related to other areas of the South China Sea. Among these 150 species, 136 species (90.7%) have also been documented on Hainan Island, 124 species (82.7%) in the Beibu Gulf, 123 species (82.0%) on Taiwan Island, and 109 species (72.7%) in Southeast Asia.

Conclusions The results indicate a strong connection between the intertidal crab population on the eastern coast of Leizhou Peninsula and the northern coast of Hainan Island. Both regions fall within the Subtropical Provinces in terms of nearshore zoobenthic biota. Interestingly, it appears that neither the Leizhou Peninsula nor the Qiongzhou Strait significantly hinder the dispersal of intertidal crabs. The results offer fresh perspectives on the biogeographical classification of nearshore zoobenthic biota in China, as well as the sustainable utilization and preservation of marine biological resources.

Key words: macrozoobenthos, crustaceans, updated checklist, Leizhou Peninsula, western Guangdong