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Abstract
Grania tasmaniae sp. n. and G. dolichura sp. n. are described from sediments collected at high‐ and low‐water mark in estuarine localities around Tasmania. They are the first named records of Grania from the southeastern corner of Australia, and the only members of the genus in Pacific waters known to possess the head organ. Grania tasmaniae has unusual spindle‐shaped coelomocytes and large, round spermathecal ampullae deeply penetrated by the ectal ducts. Grania dolichura is a relatively thin, elongate worm with trumpet‐shaped penial stylets but otherwise simple reproductive structures. Its somatic traits, however, are startling: the segment number is very high (up to 108) and the dorsal vessel exceptionally long (commencing as far back as segment LXXVIII), these two features being significantly correlated. We suggest that the increased length of body and unique vascular arrangement may enable G. dolichura to exploit deeper food sources, with the tail performing the respiratory exchange being positioned in a shallower, more oxidised layer. Grania dolichura tolerates a salinity range of 1 l‐35‰.