Bronstein O and Loya Y (2013), The taxonomy and phylogeny of Echinometra (Cama...

ECB-ART-43073

PLoS One 2013 Jan 01;810:e77374. doi: 10.1371/journal.pone.0077374.

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The taxonomy and phylogeny of Echinometra (Camarodonta: Echinometridae) from the red sea and western Indian Ocean.

Bronstein O , Loya Y .

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The number of valid species in the genus Echinometra (Echinodermata, Echinoidea) and their associated identification keys have been debated in the scientific literature for more than 180 years. As the phylogeny and dispersal patterns of these species have been widely used as a prominent model for marine speciation, new insights into their taxonomy have the potential to deepen our understanding of marine speciation processes. In this study we examine Echinometra taxonomy, combining morphology and molecular tools. We present the taxonomy and phylogeny of Red Sea and western Indian Ocean Echinometra. The currently available morphological keys were found to be limited in their ability to delineate all species within this genus. Nonetheless, morphological similarities between the Red Sea and western Indian Ocean populations were high, and delimited them from the other species. These latter populations together formed a monophyletic clade, genetically distant from any of the other Echinometra species by more than 3%. Combining both traditional taxonomy and molecular evidence, we found that these populations were neither Echinometra mathaei nor E. oblonga, as previously considered. The morphological discrepancies of these populations, and their genetic divergence from the other Echinometra species, suggest that they should be considered as a new Echinometra species.

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Genes referenced: isl1 LOC100887844

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	Figure 1. Collection sites of Echinometra specimens.(A) Map of the Indian Ocean and Eastern Pacific. Dots mark the three sampling sites: Okinawa, Zanzibar and Eilat. Detailed view of study sites: (B) Sesoko Isl., Okinawa, (C) Zanzibar, Western Indian Ocean, and (D) Eilat, Gulf of Aqaba/Eilat. Dots mark collection sites, scale bars indicate 1 km. Ca, Ba, Cu, Ki, Ja, Po, Mn, and Nu denote Changuu, Bawe, Chumbe, Kizimkazi, Jambiani, Pongwe, Mnemba and Nungwi, respectively. Ei and Ok denote Eilat and Okinawa, respectively.
	Figure 2. Spicule types of Echinometra.(A) Needle spicules in gonads of E. sp. EE. (B) Triradiate and 'figure-eight' shaped spicules in gonads of E. sp. C. (C) Triradiate spicules in tube feet of E. oblonga. (D) Bihamate spicules in tube feet of EE. Scale bars indicate 100 µm.
	Figure 3. Pore-pairs ratios of Echinometra from Eilat, Zanzibar, Okinawa and Mauritius.Mean proportion ± SE (%) of pore-pairs in Echinometra species from Eilat [Ei], Zanzibar [Zn], Okinawa [Ok], and Mauritius [Ma]. Figures in parentheses represent sample sizes. Raw data on Okinawan and Mauritian Echinometra courtesy of Yuji Arakaki.
	Figure 4. Sperm morphologies of Red Sea, Western Indian Ocean and Indo-West Pacific Echinometra.
	Figure 5. Echinometra Bayesian inference phylogenetic reconstruction tree.Consensus tree of 170,000 trees (after burn-in) generated by MCMC analysis of 20 million generations. 544 bp long COI fragments of 189 Echinometra specimens were used in the analysis. 181 sequences were generated in the current study corresponding to five Echinometra species, and a novel Echinometra mitochondrial lineage. Sequences downloaded from GenBank represent the eight known species of Echinometra and are denoted E. sp. A, E. mathaei, E. sp. C and E. oblonga, E. insularis, E. lucunter, E. viridis and E. vanbrunti (accession numbers: AY262861, AY262940, AY262932, AY262886, AY262906; AF255471, AF255530 and AF255526, from Landry et al. [4] and McCartney et al. [7], respectively). Heliocidaris crassispina (Echinodermata, Echinoidea) (GenBank accession number: JN716400) was used as outgroup. The supporting > 50% values of 1,000 bootstrap replications of the ML analysis and the posterior probabilities of the BI analysis are shown above nodes respectively. Clades A-H are discussed in the text.

References [+] :

Arakaki, Comparative studies of the genus echinometra from okinawa and mauritius. 1998, Pubmed, Echinobase