Combined evidence indicates that Perna indica Kuriakose and Nair 1976 is Perna perna (Linnaeus, 1758) from the Oman region introduced into southern India more than 100 years ago

Abstract

The specific status of the brown mussel, Perna indica, in southern India and northern Sri Lanka has long been questioned. Its limited geographical distribution within the extensive range of the Asian green mussel, P. viridis, and its morphometric similarity to the African brown mussel, P. perna, have led several authorities to suggest that P. indica is not a distinct species but is in fact introduced P. perna. Analysis of DNA sequences for nuclear ITS and mitochondrial COI sequence data from newly collected mussels from southern India examined in the context of data from GenBank for mussels of the genus Perna reveals that P. indica is indeed P. perna from the Oman region. A literature review indicates that P. indica (now P. perna) has been established in southern India for at least 100 years. Reports of ecological interactions between the native P. viridis and the introduced P. perna reveal that P. perna grows to a larger size than P. viridis and outcompetes the native mussel. P. perna forms high density populations that have long been fished by local coastal communities and recently the fishery for P. perna has expanded to markets beyond the coastal area. Eradication of the introduced P. perna is not feasible and is not desirable given its important role as a source of protein and revenue for the local community. Because no monitoring of the range of P. perna in southern India occurs it is not possible to know if this species is increasing its area of distribution, but a qualitative assessment of ongoing range expansion is made based on limited evidence from published reports. The possibility exists for inter-specific hybridisation between P. viridis and P. perna and we recommend that testing commence to check for this. This research highlights the value of a detailed understanding of the genetic structure (four different clades) of the genus Perna, without which the status of P. indica as P. perna from Oman in southern India could not have been made.