Overlooked for over a century: Ophioderma occultum sp. nov. (Echinodermata), a new species of brittle star from the Eastern Pacific

We describe a new species of ophiodermatid brittle star from the Eastern Pacific: Ophioderma occultum sp. nov. This species has been mistakenly recorded since 1899 as a colour phase of one of its congeners, Ophioderma panamense. However, the integrative use of morphological and molecular data, and comparison with type material of other Eastern Pacific Ophioderma, led to its differentiation as a novel species. Ophioderma occultum sp. nov. is characterised by having radial shields and adoral shields covered with granules, dorsal arm plates divided typically into two pieces, and a particular colour pattern: a dark grey to brown body, and arms with subtle lighter transverse bands and parallel longitudinal white bands over some median and distal segments. Molecular information based on the mitochondrial genes cytochrome oxidase subunit I (COI) and 16S also supported the species’ validity, coinciding with the morphological observations. In particular, the molecular marker 16S had not been used before for species delimitation in this genus and was proven here to be resolutive. In contrast to most species of Ophioderma from the area, Ophioderma occultum sp. nov. shows a restricted distribution to the northern Mexican Pacific (Gulf of California and islas Revillagigedo). This new species is the 10th Ophioderma described from the Eastern Pacific and the 34th worldwide. http://www.zoobank.org/urn:lsid:zoobank.org:pub:A5FFAC55-E5BE-42F6-8371-7B745911F157

本研究记述了东太平洋地区蔓蛇尾科（Ophiodermatidae）海蛇尾的1个新种：隐匿蔓蛇尾（Ophioderma occultum sp. nov.）。自1899年起，该物种便被误鉴定为其同属物种巴拿马蔓蛇尾（Ophioderma panamense）的色型。本研究通过整合形态学与分子生物学数据，并比对东太平洋地区其他蔓蛇尾属（Ophioderma）物种的模式标本，证实该物种为独立新种。

隐匿蔓蛇尾（Ophioderma occultum sp. nov.）的鉴别特征包括：辐板与口侧盾板均被颗粒覆盖；背腕板通常分为两片；具有独特的体色模式：躯体呈深灰至棕褐色，腕部部分中段及末段具浅色细微横带与平行的纵向白色条带。基于线粒体细胞色素氧化酶亚基I（cytochrome oxidase subunit I, COI）和16S基因的分子数据同样验证了该物种的有效性，与形态学观察结果一致。尤为值得注意的是，16S分子标记此前从未被应用于该属的物种界定工作，本研究证实其具备良好的物种分辨能力。

与该区域多数蔓蛇尾属物种不同，隐匿蔓蛇尾（Ophioderma occultum sp. nov.）的分布范围仅局限于墨西哥北太平洋海域，即加利福尼亚湾与雷维利亚希赫多群岛。该新种是东太平洋地区第10个被正式记述的蔓蛇尾属物种，全球范围内则为第34个。
http://www.zoobank.org/urn:lsid:zoobank.org:pub:A5FFAC55-E5BE-42F6-8371-7B745911F157