Resolving the Ophioderma longicauda (Echinodermata: Ophiuroidea) cryptic species complex: five sisters, three of them new

Sabine Stöhr,Anne Chenuil,Alexandra Anh-Thu Weber,Emilie Boissin

doi:10.5852/ejt.2020.600

Abstract

The conspicuous Mediterranean brittle star Ophioderma longicauda (Bruzelius, 1805) has been discovered to represent a cryptic species complex, consisting of six nuclear clusters with contrasting reproductive modes (broadcast spawners and brooders). Here, O. longicauda is re-described. It is distinguished by a dark reddish-brown colouration both dorsally and on the ventral disc, and multiple tumid dorsal arm plates. One eastern Mediterranean brooding cluster is described as O. zibrowii sp. nov., characterized by a dark olive-green colour both dorsally and on the ventral disc, and single dorsal arm plates. Another brooder is described from Tunisia as O. hybrida sp. nov., with a highly variable morphology that reflects its origin by hybridization of O. longicauda and a brooder (possibly O. zibrowii sp. nov.), leaving the third brooding cluster as morphologically indistinguishable at this point and possibly conspecific with one of the others. The West-African O. guineense Greef, 1882 is resurrected as a valid species, differing morphologically from O. longicauda by predominantly single dorsal arm plates and light green or creamy white ventral side. Also from West Africa, O. africana sp. nov. is described, characterized by a dark brown colour, dorsally and ventrally, and single dorsal arm plates.

Highlights

Ophioderma longicauda (Bruzelius, 1805) is a large and conspicuous species of brittle star, reported from the coast of the Mediterranean Sea and in the East Atlantic Ocean from Portugal to West Africa (Stöhr et al 2009)
Another brooder is described from Tunisia as O. hybrida sp. nov., with a highly variable morphology that reflects its origin by hybridization of O. longicauda and a brooder, leaving the third brooding cluster as morphologically indistinguishable at this point and possibly conspecific with one of the others
Two broadcast spawning species are found off West Africa, two brooders are only found in the eastern Mediterranean Sea and may form a single species or two, one species ranges from the Canary Islands across the entire Mediterranean Sea and was identified as O. longicauda s. str., and one brooding species seems to be restricted to Tunisia (Fig. 1)

Summary

Introduction

Ophioderma longicauda (Bruzelius, 1805) is a large and conspicuous species of brittle star, reported from the coast of the Mediterranean Sea and in the East Atlantic Ocean from Portugal to West Africa (Stöhr et al 2009) It has been collected at Madeira and the Canary Islands (Boissin et al 2011). It was discovered that there are individuals in the easternMediterranean populations of Ophioderma Müller & Troschel, 1840, morphologically extremely similar to O. longicauda, but reproducing by brooding eggs and young (Stöhr et al 2009) It was at first unclear if this was a rare case of poecilogony or evidence of a cryptic species complex. This means that at least three species are taxonomically undescribed and unnamed

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Conclusion