Description, systematics and ecology of a new tanaidacean (Crustacea, Peracarida) species from mediterranean fish farms

P Esquete,V Fernandez-Gonzalez

doi:10.1186/s10152-016-0480-9

Abstract

An undescribed species of tanaidacean belonging to the genus Hexapleomera, tribe Pancolini, Hexapleomera bultidactyla sp. nov. was found in fouling community samples from off-coast fish farms cages in the western Mediterranean Sea. The species can be distinguished from other Hexapleomera species by the presence of a ventral apophysis on the dactylus of the chela in males. Other diagnostic characters (in combination) include a male antennule with five aesthetascs, the female with three, the maxillule palp with four terminal setae and maxilliped basis and coxa each with two setae; the male fixed finger with four ventral setae and proximal apophysis, the female chela fixed finger with a proximal triangular apophysis, an apophysis on the coxa of pereopod 1, a pleopod 3 basis with three outer setae, and an uropod of four segments. Although several substrata were investigated, the species was most abundant where the turf formed by Ceramiaceae algae and the hydroid Aglaophenia sp. was dominant. An updated identification key to all the species of Hexapleomera is provided.

Highlights

Tanaidaceans (Order Tanaidacea Dana, 1846) are a group of peracarid crustaceans that are frequently found in very high densities, accounting for a significant proportion of the benthic community
Ecology and distribution The current numbers and density of fish cages scattered along some of the Mediterranean coasts provide a significant amount of hard substrata in off-coast areas where they are naturally absent, boosting the dispersion of associated species [9]
Macroinvertebrate species associated with fish farms have been shown to assimilate the organic matter derived of uneaten feed pellets and fish faeces [10], and tanaidaceans may take advantage of this new trophic resource

Summary

Introduction

Tanaidaceans (Order Tanaidacea Dana, 1846) are a group of peracarid crustaceans that are frequently found in very high densities, accounting for a significant proportion of the benthic community. They are considered to have a sedentary lifestyle, with limited displacement capacity and no obligate dispersive phase in their life history, which leads to allopatric speciation, niche specificity and high frequency of endemic species [1]. The genus Hexapleomera Dudich, 1931 was described in order to accommodate the species Hexapleomera robusta (Moore, 1984) [2], previously included in the genus Tanais Latreille, 1831. Hexapleomera was long considered monotypic, and the type species H. robusta cosmopolitan [2]. Bamber [4] revised material from various collections

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