First confirmed reports of the rhizostome jellyfish Mastigias (Cnidaria: Rhizostomeae) in the Atlantic basin

Keith Bayha,William Graham

doi:10.3391/ai.2011.6.3.13

Abstract

The rhizostome jellyfish Mastigias (Agassiz, 1862), native to the western and central Indo-Pacific, is recorded from the western Atlantic, in a marine lake in Puerto Rico (Laguna Joyuda) and a working quarry on No Name Key, Florida (USA) in the Florida Keys. The single individual from Laguna Joyuda, collected in 2002, was previously misidentified as Phyllorhiza (Agassiz, 1862) and Mastigias has not since been recorded there, while a large population of Mastigias was observed in No Name Key in 2009 and 2010 and may have been present for decades. Identification as Mastigias for both sampling sites was confirmed by molecular systematic analysis of mitochondrial cytochrome c oxidase I (COI) and ribosomal 16S (16S). Sequences from both molecular markers were identical for all individuals sampled from Puerto Rico and the Florida Keys. Phylogenetic analysis of COI indicated that the introduced Mastigias were most closely related to Mastigias sp. 1 (Dawson, 2005) from Kakaban, Indonesia (Kimura 2-parameter sequence divergence = 1.1%) and distantly related to Mastigias papua (Lesson, 1830) from Palau (6.4-7.2%) and Mastigias sp. 2 (Dawson, 2005) from Papua New Guinea (9.8%). Therefore, the source region may lie somewhere in the central Indo-Malayan region, though determining an exact source region is not possible at this time. While the invasion vector is unclear, possible mechanisms include commercial shipping, mobile oil platforms and live rock transport. These are the first two confirmed records of Mastigias in the Atlantic basin and the second confirmed identification of the genus occurring outside of the native range, after Hawaii.

Highlights

The jellyfish genus Mastigias (Scyphozoa: Rhizostomeae) is native to the western and central Indo-Pacific, from Australia to Japan, and Micronesia to the Indian Ocean (Kramp 1961)
Investigations of Mastigias populations from marine lakes in Palau have revealed important information regarding evolution within the species Mastigias papua, indicating rapid and profound ecological and behavioral adaptation that accompanied their isolation in newly formed marine lakes (Dawson and Hamner 2003; Dawson and Hamner 2005), as well as the formation of multiple subspecies of Mastigias (Dawson 2005a)
Since the use of molecular genetic techniques has been instrumental in determining species boundaries in scyphozoan jellies (Dawson and Jacobs 2001; Holland et al 2004; Dawson 2005b; Bayha and Dawson 2010) as well as correcting morphological misidentifications of gelatinous zooplankton from past publications (Gorokhova et al 2009), we sequenced mitochondrial c oxidase I (COI) and 16S for three individuals from No Name Key and one individual from Laguna Joyuda

Summary

Introduction

The jellyfish genus Mastigias (Scyphozoa: Rhizostomeae) is native to the western and central Indo-Pacific, from Australia to Japan, and Micronesia to the Indian Ocean (Kramp 1961). During a morphology-based study of worldwide populations of Phyllorhiza designed to indicate source region(s) of invaders, Bolton and Graham (2004) examined Phyllorhiza medusae from six worldwide populations, including Laguna Joyuda, Puerto Rico (Figure 1).

Results

Conclusion