Named Haliotis pirimoana, the newly-identified gastropod species is only found at Manawatāwhi Three Kings Islands, off New Zealand’s North Island.
Shells of Haliotis pirimoana from Manawatāwhi Three Kings Islands (A-D) and Haliotis virginea (E-G). Scale bar – 5 mm in (A-C) and 0.5 mm in (D-G). Image credit: Jean-Claude Stahl.
Abalones (family Haliotidae) are herbivorous marine gastropods that occupy hard substrates in shallow non-polar regions worldwide.
Several haliotids are the basis of wild-caught and/or aquaculture fisheries.
Additionally, their shells are often prized for art, cultural practices, jewellery, and by shell collectors.
Presently, almost 70 species and many subspecies and forms are scientifically recognized, all in the genus Haliotis.
Haliotis pirimoana lives at 5-47 m depth under rocks and in rock crevices at Manawatāwhi Three Kings Islands.
This new species differs subtly but consistently in having finer and more numerous spiral threads than the endemic New Zealand abalone Haliotis virginea at an equivalent stage of growth.
“Haliotis pirimoana superficially resembles specimens from North Island (except near Wellington) populations of Haliotis virginea in shell morphology, but, at an equivalent stage of growth differs considerably in having consistently finer spiral threads on the dorsal surface that are more evenly spaced, with narrower interspaces, and a more tightly coiled columella,” said Dr. Kerry Walton, a researcher at the University of Otago and Museum of New Zealand Te Papa Tongarewa, and colleagues.
“These differences are particularly evident when shells from the far north of the North Island, closest to the Three Kings Islands, are compared with Haliotis pirimoana: the former have a distinctly coarser sculpture.”
“Haliotis pirimoana differs further from mainland populations of Haliotis virginea in average shell shape: generally having a lower profile, especially abapically, a more angular abapical margin, and a flatter, broader, and more sharply delimited umbilical margin.”
According to the study authors, whether Haliotis pirimoana has a relictual distribution at Three Kings Islands or diverged there from Haliotis virginea following a period of isolation is unknown.
“The shallow sublittoral fauna at the Three Kings Islands has extremely high regional endemism,” they said.
“The drivers of high, localised levels of endemism at the Three Kings Islands remain unclear, but this phenomenon is no doubt influenced by successive periods of connectivity and isolation during glacial cycles since the Miocene epoch.”
“The strong upwelling may result in more stable water conditions during glacial cycles.”
“Given the small size of the Three Kings region, its accessibility from mainland New Zealand, its proximity to major shipping routes, and the extreme degree of regional endemism, the region could benefit from addition of greater marine protection.”
The discovery of Haliotis pirimoana is reported in a paper in the journal Molluscan Research.
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Kerry Walton et al. Haliotis virginea Gmelin, 1791 and a new abalone from Aotearoa New Zealand (Mollusca: Gastropoda: Haliotidae). Molluscan Research, published online August 30, 2024; doi: 10.1080/13235818.2024.2390476
Source : Breaking Science News