Persistent Gaps of Knowledge for Naming and Distinguishing Multiple Species of Crown-of-Thorns-Seastar in the Acanthaster planci Species Complex

Abstract

Nearly a decade ago, DNA barcoding (partial mitochondrial COI gene sequences) showed that there are at least four species in the Indo-Pacific within what was previously conceived to be a single Crown-of-Thorns-Seastar (COTS) species, Acanthaster planci. Two of these species-A. planci Linnaeus, 1758, distributed in the North Indian Ocean, and A. mauritiensis de Loriol, 1885, distributed in the South Indian Ocean-have been already unequivocally named. In contrast, the Pacific COTS (proposed name: A. solaris (Schreber, 1795) and the COTS from the Red Sea (still to be named) require further taxonomic work. COI barcoding sequences and Barcode Identification Numbers (BINs) are available for all four COTS species in the global Barcode of Life Database (BOLD). We recommend depositing voucher specimens or tissue samples suitable for DNA analyses when studying any aspect of COTS, and use BINs to identify species, to ensure that no information is lost on species allocation until unequivocal Linnean names are available for the Pacific and Red Sea species as well. We also review the differences between COTS species with respect to morphology, ecology, and toxicity. Future studies should widen the current biogeographic coverage of the different COTS species by strategically sampling neglected areas, especially at the geographic distribution limits of each species, to enhance our understanding of the diversity of this reef coral predator.

30 Years of Research on Crown-of-thorns Starfish (1986-2016): Scientific Advances and Emerging Opportunities

“…The relatively high (8.8-10.6%) genetic distance among the four-aforementioned species, based on the COI marker used for 'barcoding', suggests that these species diverged 1.95 to 3.65 million years ago (Vogler et al 2008). Within the four nominal species, genetic divergence was greatest for the Pacific population (Haszprunar et al 2017), and other studies have revealed conspicuous genetic structure when comparing among CoTS from different regions across the Pacific (Timmers et al 2012;Vogler et al 2013). Moreover, distinctive phenotypes of Acanthaster spp.…”

“…The third major species (A. mauritiensis) is generally restricted to the south-western Indian Ocean, but does co-occur with A. planci in the Oman Sea (Vogler et al 2008). There is also a fourth distinct species restricted to the Red Sea, which is yet to be formally described and named (Haszprunar et al 2017). The relatively high (8.8-10.6%) genetic distance among the four-aforementioned species, based on the COI marker used for 'barcoding', suggests that these species diverged 1.95 to 3.65 million years ago (Vogler et al 2008).…”

“…Therefore, this review also considers some of the foremost new directions for CoTS research, related to i) systematics and biogeography, ii) genetic and genomic sampling, iii) ecological modelling and iv) projected effects of environmental change. Notably, genetic sequencing of CoTS populations from throughout their geographic range (Red Sea to the eastern Pacific) has resolved that there are several distinct species (Vogler et al 2008;Haszprunar et al 2017); Acanthaster planci, which is restricted to the northern Indian Ocean, is readily distinguishable from the Pacific species (A. cf. solaris) based on color, as well as a general lack of spines along the aboral distal portion of the arms (Fig.…”

“…2). Overall, there are at least four distinct and geographically separated species (Vogler et al 2008;Haszprunar et al 2017), though most of the research and knowledge of CoTS biology and ecology comes from research in the western Pacific on A. cf. solaris.…”

“…from throughout the Indo-Pacific ostensibly look and behave the same way, but devastating impacts of crown-of-thorns starfish appear to be confined to the Pacific, which is the geographical range of A. cf. solaris (Haszprunar and Spies 2014;Haszprunar et al 2017). This warrants explicit comparisons of reproductive and larval ecology, demographic rates, feeding rates and feeding preferences among Acanthaster spp.…”