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| Acanthaster benziei Wörheide & Kaltenbacher in Wörheide, Kaltenbacher, Cowan & Haszprunar 2022 |
Abstract
A new species of crown-of-thorns sea star (CoTS), Acanthaster benziei sp. nov., is described based on four specimens collected from Saudi Arabia’s Red Sea coast where it inhabits coral reefs. Species delimitation from congeners in the species complex, i.e., Acanthaster planci, Acanthaster mauritiensis and Acanthaster cf. solaris, is primarily based on distinct and diagnostic mitochondrial DNA sequence regions. Species separation of Acanthaster benziei is additionally justified due to diagnostic morphological characters: fewer arms; narrower and thinner spines; fanned spine tips in primary and latero-oral spines; a wider tip or tapering shape in circumoral spines; and rhombus-shaped oral pedicellariae.
Key words: Acanthasteridae, Acanthaster, morphology, taxonomy, Red Sea, coral reefs
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| Acanthaster benziei sp. nov. Ethanol-preserved specimens of the type series. GW4202 (A) is the holotype, all the others (B–D) are paratypes. Note that individual GW4266 is a juvenile specimen. Size of labels 6 × 2 cm. |
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| Typical colouration of Acanthaster benziei sp. nov. (A) GW4081 (Paratype, hiding during the day under a crevice), Al-Lith, Saudi Arabia, (photo credit: Oliver Voigt), (B–D) Thuwal Reefs, Saudi Arabia (photo credit: Gert Wörheide). Approximate diameter of specimens is 25–30 cm. |
Acanthaster benziei sp. nov. Wörheide & Kaltenbacher
in Wörheide, Kaltenbacher, Cowan & Haszprunar 2022
Differential diagnosis. Acanthaster benziei sp. nov. can clearly be distinguished by diagnostic mutations in the partial COI gene sequences analysed, all material examined fall within the deeply divergent monophyletic group of CoTS from the Red Sea (see Fig. 3). There is full agreement with initial results that proposed species distinction of the Red Sea clade based on COI data alone (Vogler et al. 2008), recently corroborated by nuclear genome analyses (Yuasa et al. 2021). The molecular-based species distinction of A. benziei sp. nov. is also substantially supported by diagnostic morphological characters.
Acanthaster benziei has fewer arms than congenericsea stars of comparable size from the other geographic regions/species. Our reported range between 11 and 14 arms in the type series (Tab. 3) is consistent with values previously reported for other individuals from the Red Sea (mean of 13 arms [Campbell and Ormond 1970]; maximum of 13–14 arms [Haszprunar et al. 2017]). By contrast, the number of arms reported for sea stars from India (= A. planci) was 15 (Linnaeus 1758) and for A. mauritiensis 13–16 (de Loriol 1885), with a maximum of 23 arms reported for A. planci, A. mauritiensis and the Pacific species A. cf. solaris (Haszprunar et al. 2017) (see Supp. Tab. 1).
Etymology. The species name pays tribute to Professor John Benzie, who has decisively promoted research on CoTS, with numerous publications and his own collection. He was among the first scientists to genetically analyse Acanthaster spp. and his collection was the basis of the work of Vogler et al. (2008), which represents a milestone in the species identification of these sea stars.
Distribution and habitat. So far known Acanthaster benziei is restricted to the Red Sea, where it inhabits coral reefs, predominantly the outer reef surfaces where it mostly hides in crevices during the day and feeds nocturnally.
Gert Wörheide, Emilie Kaltenbacher, Zara-Louise Cowan and Gerhard Haszprunar. 2022. A New Species of Crown-of-Thorns Sea Star, Acanthaster benziei sp. nov. (Valvatida: Acanthasteridae), from the Red Sea. Zootaxa. 5209(3); 379-393. DOI: 10.11646/zootaxa.5209.3.7
