Melinnacheres M. Sars, 1870

Boxshall, Geoff A., O’Reilly, Myles, Sikorski, Andrey & Summerfield, Rebecca, 2019, Mesoparasitic copepods (Copepoda: Cyclopoida) associated with polychaete worms in European seas, Zootaxa 4579 (1), pp. 1-69 : 34

Genus Melinnacheres M. Sars, 1870

Syn: Saccopsis Levinsen, 1878

Oestrella M’Intosh, 1885

Diagnosis. Adult female typically with unsegmented ovoid to conical body (ectosoma), attached to host via short stalk located anteriorly on ventral surface, leading to short bulla (endosoma) inserted in host. Ectosoma lacking defined cephalothorax but retaining paired antennules, antennae and maxillae located around base of stalk originating in oral region. Trunk often with paired surface depressions or internal cuticular sutures representing traces of segmental organization; lacking any vestiges of post-cephalic limbs. Genital apertures paired, carried on conspicuous swellings located on or near posterior margin. Paired cement glands curved, well developed and visible through body wall. Median anal prominence with anal slit present or absent. Egg sacs paired, multiseriate.

Adult male ovoid, indistinctly divided into anterior cephalothorax and posterior trunk. Cephalothorax bearing paired antennules frontally plus antennae and maxillae located around oral region. Oral region with funnel-like chitinous framework enclosing paired lobate structures possibly representing mandibles. Trunk lacking vestiges of limbs. Caudal rami absent. Antennules indistinctly segmented, setose. Antennae 2-segmented with paired apical pads. Maxillae with robust proximal segment and broad distal segment bearing paired adhesion pads.

Type species: Melinnacheres ergasiloides M. Sars, 1870 , by original monotypy.

Remarks. Melinnacheres is a distinctive genus characterised by its undifferentiated ectosoma bearing three pairs of cephalic appendages located in the oral region around the base of the stalk. The small bulla-like endosoma is also distinctive, differing markedly from the large endosoma of the Bradophilidae , Herpyllobiidae , and Phyllodicolidae . The characteristics of the dwarf adult males were first elucidated in detail by Bresciani & Lützen (1975). Species of this genus have been reported from ampharetid and terebellid hosts.