Molecular and morphological systematics of Bursatella leachii de Blainville, 1817 and Stylocheilus striatus Quoy & Gaimard, 1832 reveal cryptic diversity in pantropically distributed taxa (Mollusca : Gastropoda : Heterobranchia)

The ragged sea hare (Bursatella leachii) and the long-tailed sea hare (Stylocheilus striatus) are two widely distributed species of benthic heterobranch sea slugs. In this paper, integrative taxonomic analyses have been conducted to detect possible cryptic diversity. Our results revealed that both nominal species are actually species complexes, consisting of five genetically distinct taxa. Two of them belong to the genus Bursatella and three to the genus Stylocheilus. The name B. leachii is retained for a widely distributed species, present in the Atlantic, the Mediterranean, and parts of the Indo-Pacific region. The name B. ocelligera is resurrected for the other species, restricted to the Indo-Pacific and co-occurring with B. leachii in that area. With the present data, it is not possible to test whether B. leachii and B. ocelligera have evolved allopatrically in the Atlantic and Indo-Pacific or sympatrically in the latter. Bursatella leachii has been able to maintain gene flow between the Atlantic and the Indo-Pacific Oceans, possibly because of a combined effect of the Agulhas Leakage process and the ability to survive the colder waters of South Africa. On the contrary, the three species of Stylocheilus are allopatric; the name S. striatus is retained for an Indo-Pacific species, while the names S. polyomma and S. rickettsi are resurrected for species inhabiting the Western Atlantic and the Eastern Pacific respectively. Finally, the discovery of a museum specimen mistakenly identified as B. leachii, but bearing a shell in its adult form, led to the resurrection of the genus Phycophila, previously synonymised with Aplysia. Phycophila euchlora, the only species described to date, is distributed in the Central and Western Pacific Ocean.

The effects of sound on the survivorship and embryonic development of a marine gastropod Stylocheilus striatus, (aplysiidae)

How anthropogenic noise pollution affects marine organisms is drawing increasing international concern. There is evidence for anthropogenic noise having negative and harmful effects on the health, development and behavior of many terrestrial species; however, there are few examples of how specific frequencies of sound affect the survivorship and embryonic development of marine invertebrates. This experiment examines the effects of specific frequencies of sound on the survivorship and embryonic development of a marine gastropod, Stylocheilus striatus on the island of Mo’orea, French Polynesia. It was found that high frequency sound treatments caused a delay in the embryonic development of S. striatus embryos by 3 days while decreasing veliger survivorship by 37%. Additionally, high frequency treatments were shown to cause an observed morphological difference in shell morphology as compared to control and low frequency treatment groups. This study can be used to aid in the management and planning of future conservation polices regarding sound pollution and marine invertebrate gastropods as their presence is crucial for reef health and community structure.

The effects of sound on the survivorship and embryonic development of a marine gastropod Stylocheilus striatus, (aplysiidae)

How anthropogenic noise pollution affects marine organisms is drawing increasing international concern. There is evidence for anthropogenic noise having negative and harmful effects on the health, development and behavior of many terrestrial species; however, there are few examples of how specific frequencies of sound affect the survivorship and embryonic development of marine invertebrates. This experiment examines the effects of specific frequencies of sound on the survivorship and embryonic development of a marine gastropod, Stylocheilus striatus on the island of Mo’orea, French Polynesia. It was found that high frequency sound treatments caused a delay in the embryonic development of S. striatus embryos by 3 days while decreasing veliger survivorship by 37%. Additionally, high frequency treatments were shown to cause an observed morphological difference in shell morphology as compared to control and low frequency treatment groups. This study can be used to aid in the management and planning of future conservation polices regarding sound pollution and marine invertebrate gastropods as their presence is crucial for reef health and community structure.