Pristiorhynchus palmi n. g., n. sp. (Cestoda: Trypanorhyncha) from sawfishes (Pristidae) off Australia, with redescriptions and new records of six species of the Otobothrioidea Dollfus, 1942

A new genus of trypanorhynch cestodes, Pristiorhynchus n. g. (Otobothrioidea: Otobothriidae), is described from two species of modern sawfishes (Pristidae) from off northern Australia. Pristiorhynchus palmi n. g., n. sp. is characterised by an acraspedote scolex with two bothria, paired bothrial pits on the posterior margins of each bothrium, the absence of gland-cells within the bulbs and prebulbar organs, a retractor muscle inserting at the posterior region of the elongate bulbs, a characteristic basal tentacular armature with dispersed billhooks and a heteroacanthous atypical metabasal armature with five principle and three intercalary hooks. Furthermore, redescriptions are provided for Symbothriorhynchus tigaminacantha Palm, 2004, Parotobothrium balli (Southwell, 1929) and Pseudotobothrium arii (Bilqees & Shaukat, 1976). Observations of adult worms revealed novel information on the segment morphology, which has not been described for these three species. Specimens of Proemotobothrium linstowi (Southwell, 1924), Pr. southwelli Beveridge & Campbell, 2001 and Fossobothrium perplexum Beveridge & Campbell, 2005 collected from elasmobranchs from several sampling localities off Australia revealed additional information on host range and geographical distribution.