Abstract
A putative new species of tantulocaridan is reported parasitizing a species of typhlotanaid (Tanaideacea) from the Gulf of Mexico at depths up to 2767 m. The tantulocaridan belongs to Microdajus Greve, 1965, species of which are all known from tanaid hosts in the superfamily Paratanoidea. Tantulocaridan samples included newly settled tantulus larvae, early stages of trunk development and developing males; parasites were found attached to anterior appendages (antennules and pereopods) or bodies of hosts. This material likely represents a new species but the condition and number of available specimens precludes a formal description. The putative new species is most similar to Microdajus aporosus Grygier and Sieg, 1988 and Microdajus tchesunovi Kolbasov and Savchenko, 2010 in having an endopodal seta on each of the sixth thoracopods (lacking in other species). Microdajus tchesunovi is the only described species of Microdajus with males bearing unsegmented sixth thoracopod protopods; this character is also found on the present specimens. Males of the newly reported tantulocaridan can be distinguished from those of M. tchesunovi based on protopod 1-5 morphology and setation of the pits on the cephalothorax (fewer setae in males of the western Atlantic specimens compared to M. tchesunovi). This is the first species of Microdajus reported from the western Atlantic and the first tantulocaridan known from the Gulf of Mexico or northwestern Atlantic.
Keywords
Gulf of Mexico; Multicrustacea; parasite; tantulus larva; Typhlotanaidae
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