Leptostracans (Crustacea: Phyllocarida) from mud volcanoes at the Gulf of Cadiz (NE Atlantic) with description of a new species of Sarsinebalia Dahl, 1985

Juan Moreira,Patricia Esquete,Marina R Cunha

doi:10.5852/ejt.2021.736.1255

Juan Moreira, Patricia Esquete + Show 1 more

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https://doi.org/10.5852/ejt.2021.736.1255

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Abstract

Three leptostracan species (Crustacea: Phyllocarida) are reported from mud volcanoes at the Moroccan margin of the Gulf of Cadiz (NE Atlantic). Nebalia strausi Risso, 1826 and N. abyssicola Fage, 1929 were found in experimentally deployed organic substrates in Mercator, Meknès and Darwin mud volcanoes; N. abyssicola was also found among bathymodiolin bivalves and is recorded for the first time in the Atlantic Ocean. The third species was collected from the Gemini mud volcanoes and is described herein as Sarsinebalia ledoyeri sp. nov. The new species is characterised by having the eyes provided with ommatidia and lacking pigment, the ventral margin of the eye is concave along distal half, the antennular scale is more than twice as long as wide, the second article of the mandibular palp bears one seta on lateral surface about 0.5 times as long as the article and one subterminal seta longer than the third article, the distal article of the maxilla II endopod is about 1.8 times as long as the proximal article, the maxilla II exopod is clearly longer than the endopod proximal article, the lateral margin of the pleopod I exopod lacks setae and the posterodorsal border of pleonites VI–VII is provided with rounded to pointed denticles.

Highlights

IntroductionThe number of known species of extant leptostracans (Crustacea: Phyllocarida) has been substantially expanded in the last decades, with descriptions of new taxa from many areas around the globe, including North and Central America (Modlin 1991; Escobar-Briones & Villalobos-Hiriart 1995; Martin et al 1996; Vetter 1996b; Haney & Martin 2000, 2004, 2005; Haney et al 2001; Ortiz et al 2011), eastern and southeast Asia (Lee & Bamber 2011; Song et al 2012b, 2013, 2017; Song & Min 2017), southwest Africa (Bochert & Zettler 2012), western Pacific Ocean (Ledoyer 2000) and Australia (Walker-Smith 1998, 2000)
McCormack et al (2016) recently reviewed the characters considered diagnostic for Sarsinebalia and concluded that further work is needed to assess the validity of the genus, including a molecular approach
The new species described here was tentatively included in Sarsinebalia mostly because it has a rostrum with subterminal spine and it lacks a ‘comb-row’ of bi-pectinate setae on the lateral margin of the pleopod I exopod; such setae are present instead in Nebalia, Dahlella Hessler, 1984, Paranebalia and Levinebalia Walker-Smith, 2000 (Haney & Martin 2004)

Summary

Introduction

The number of known species of extant leptostracans (Crustacea: Phyllocarida) has been substantially expanded in the last decades, with descriptions of new taxa from many areas around the globe, including North and Central America (Modlin 1991; Escobar-Briones & Villalobos-Hiriart 1995; Martin et al 1996; Vetter 1996b; Haney & Martin 2000, 2004, 2005; Haney et al 2001; Ortiz et al 2011), eastern and southeast Asia (Lee & Bamber 2011; Song et al 2012b, 2013, 2017; Song & Min 2017), southwest Africa (Bochert & Zettler 2012), western Pacific Ocean (Ledoyer 2000) and Australia (Walker-Smith 1998, 2000). Most of the extant leptostracan species belong to the genus Nebalia Leach, 1814, for a total of 11 species in European latitudes and the Mediterranean Sea (Dahl 1985; Ledoyer 1997; Moreira et al 2009a; Koçak et al 2011; McCormack et al 2016; Latry & Droual 2020). There are three other species described from European temperate latitudes: S. biscayensis Ledoyer, 1998 from deep-sea waters at the Bay of Biscay, and S. cristoboi Moreira et al, 2003 and S. urgorrii Moreira et al, 2003, both from shallow coarse and medium sand at the western Iberian Peninsula (Moreira et al 2003b; Sampaio et al 2016); S. urgorrii has been reported from around the British Isles (McCormack et al 2016) and French Atlantic and Mediterranean waters (Latry & Droual 2020). Species mostly differ in the presence of ommatidia and pigment (both absent in S. typhlops, S. biscayensis and S. pseudotyphlops Petryashov, 2016) and the shape of eye

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