Family HOLOGNATHIDAE Thomson, 1904

Cleantioides striata

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Family HOLOGNATHIDAE Thomson, 1904

Holognathidae Thomson, G.M. 1904. A new family of Crustacea Isopoda. Annals and Magazine of Natural History 7 14: 66-69 [67].

Introduction

The family Holognathidae was erected for a single species Holognathus stewarti (Filhol, 1885) possessing a mandibular palp, the only valviferan to have one. Other species are now included in the family. All possess a cylindrical shape and pereopod 4 shorter than other pereopods. Holognathids are an unusual group of idoteid-like valviferans, many of which are tubicolous in the hollow stems of seagrasses (Issel 1912; Hale 1929). A revision by Poore & Lew Ton (1990) and more recent discoveries have expanded the family diagnosis to include 27 species in five genera from most seas.

Diagnosis

Body more or less flattened or semicylindrical, coxae with expanded coxal dorsal plates, pleonites with expanded epimera, straight, without flexion, parallel-sided over most of length. Head and pereonite 1 free. Head more or less semi-cylindrical. Pereopod 1 gnathopod-like; pereopods 2–7 ambulatory, similar, with marginal short robust setae, pereopod 4 shorter and more spinose than pereopods 3 and 5; with prominent dactyli, unguis short. Uropodal exopod (smaller ramus) ovate, fringed with setae (if present). Pleopod 1 peduncle shorter than or as long as rami (similar to other pleopods); exopod of male laminar.