On an unusual shallow occurrence of the deep-sea brittle star Ophiomyces delata in the Duncan Passage, Andaman Islands (Northern Indian Ocean)

Abstract

The deep-water brittle star Ophiomyces delata Koehler, 1904 is reported from the Duncan Passage, Andaman Islands, for the first time, at a relatively shallow depth of 56 m. A detailed description of the specimens is provided, as the genus Ophiomyces comprises nine nominal species that exhibit morphological plasticity and have considerable overlap in geographic range. The recently resurrected name for the family, Ophiomycetidae Verrill, 1899, is replaced with the senior synonym Ophiohelidae Perrier, 1893, and a key to genera is provided. This family represents a strongly conservative lineage among Ophiuroidea, having originated in the deep-sea and temporarily extended their range to shallow shelf settings around the middle Jurassic, before apparently retreating to bathyal and abyssal depths. The present discovery of Ophiomyces delata represents the first report of this lineage at shallow depths since the mid-Jurassic.

First occurrence of an Ophiohelidae species in the Mediterranean: the high abundances ofOphiomyces grandisfrom the Mallorca Channel seamounts

“…Identification was done according to Lyman (1869, 1879), Mortensen (1927), Ziesenhenne (1940), Paterson (1985), Litvinova (2001) and Parameswaran et al . (2015). The terminology applied for the morphological description follows Stöhr et al .…”

“…The ophiuroid family Ophiohelidae Perrier, 1893, only represented by 19 species, has been recently resurrected by Parameswaran et al . (2015). These authors followed Thuy & Meyer (2013) who conclusively separated the genera Ophiomyces Lyman, 1869, Ophiohelus , Lyman, 1880, Ophiotholia Lyman, 1880 and Ophiothauma H. L. Clark, 1938, from the family Ophiacanthidae Ljungman, 1867 and placed them back into the family Ophiomycetidae Verrill, 1899, considered by Parameswaran et al .…”

“…These authors followed Thuy & Meyer (2013) who conclusively separated the genera Ophiomyces Lyman, 1869, Ophiohelus , Lyman, 1880, Ophiotholia Lyman, 1880 and Ophiothauma H. L. Clark, 1938, from the family Ophiacanthidae Ljungman, 1867 and placed them back into the family Ophiomycetidae Verrill, 1899, considered by Parameswaran et al . (2015) as a junior synonym of Ophiohelidae. More recently, O'Hara et al .…”

“…Due to the presence of this species in the Pacific Ocean overlapping with the distribution range of O. delata and the morphological resemblance of both species, Parameswaran et al . (2015) proposed the possibility that they could be synonymous or that together they represent a multi-species complex. Such taxonomic uncertainties have promoted the application of molecular genetics approaches such as DNA barcoding (Hebert et al ., 2003), a method that has successfully been used for species discrimination or the discovery of cryptic species complexes (e.g.…”

A New Morphological Phylogeny of the Ophiuroidea (Echinodermata) Accords with Molecular Evidence and Renders Microfossils Accessible for Cladistics

“…[ 21 ] and Parameswaran et al . [ 23 ]. Family types are preceded by an asterisk, fossil ones are marked by a cross.…”