Eubostrichus fertilis sp. n., a new marine nematode (Desmodoridae: Stilbonematinae) with an extraordinary reproductive potential from Belize, Central America

Eubostrichus fertilissp. n. is described from fine subtidal sands in the Belize Barrier Reef system using LM and SEM illustrations and the sequence of the 18S rRNA gene. The new species is one of the smallest (mature specimens ranging from 1.88 to 3.03 mm) and the stoutest (a = 36-80) of all previously describedEubostrichusspecies. The closest relatives areE. parasitiferusandE. hopperi. It differs from the former in the more posterior position of the vulva and the postanal porids, and from the latter in the smaller size of the amphids, the shorter cephalic setae and the shape of the tail. Furthermore, it is remarkable for the prominent extent of the female genital system. Females have up to 18 eggs of similar size in their uteri. The body of the worm is covered by large (up to 45 μm long) crescent-shaped bacteria attached with both poles to the cuticle of the worm in a spiral pattern. The genusEubostrichusis phylogenetically well supported on the basis of the 18S rRNA gene sequence.Eubostrichus gerlachinom. nov. (= E. parasitiferusapudGerlach, 1963necChitwood, 1936) is proposed.