Southernmost record of an epibiotic alga Pseudocladophora conchopheria (Sakai) Boedeker & Leliaert (Cladophorales, Ulvophyceae) with insights into the geographical dispersal and host utilization

Abstract

The accumulation of information on the geographical distribution range, genetic structure, and host utilization of the symbiont is important for studying how the symbiont spreads its distribution. Pseudocladophora conchopheria is a green alga that grows on the shells of intertidal gastropods distributed in the Japanese Archipelago, the Ryukyu Archipelago, and the southern part of Korean Peninsula. However, we discovered algae similar to P. conchopheria on the shells of gastropods from Vietnam. Therefore, species identification of the algae and the host gastropods was performed based on morphological observations and molecular genetic methods. As a result, the morphological characteristics of the algae were consistent with those of P. conchopheria, and the morphological characteristics of the host gastropods were consistent with those of Lunella granulata. Molecular genetic methods further supported these results of morphological identification. Interestingly, their algae were more closely related to P. conchopheria attached to L. correensis from the Sea of Japan rather than those attached to L. granulata from the Ryukyu Archipelago. These results suggest that P. conchopheria has expanded its distribution by utilizing multiple hosts and are explained on a wider scale than previous findings.