Palp morphology in two species of Prionospio (Polychaeta: Spionidae)

The palp morphology of Prionospio fallax Söderström, 1920 from Sweden and Prionospio cf. saldanha Day, 1961 from Thailand was examined with a scanning electron microscope. Prionospio fallax was also studied in vivo using light-microscopy. Both species have grooved feeding palps, adorned with up to five ciliary characters: frontal cilia, transverse ciliary bands (or bandlets), latero-frontal cirri, lateral cilia and randomly distributed non-motile cirri. All, except the frontal cilia and non-motile cirri, are asymmetrically arranged relative to the long axis of the palps. Prionospio fallax possesses transverse bandlets and the other four groups, while P. cf. saldanha has transverse bands (consisting of several contiguous bandlets), frontal cilia and some randomly scattered cirri. Asymmetrical palp ciliation was previously only known in Marenzelleria viridis (Verril, 1873) and the genus Scolelepis Blainville, 1828. The newly recognised transverse ciliary bands and bandlets are considered to be homologous with the transverse ciliary rows found basally on the palps of Paraprionospio pinnata (Ehlers, 1901). This multistate character (named transverse cilia) may prove useful in elucidating the phylogeny of the Prionospio-complex of genera.     

Prionospio atrovitta (Annelida: Spionidae), a new species from Andaman and Nicobar archipelago,northern Indian Ocean

ABSTRACT

A new species of polychaete, Prionospio atrovitta, is described from the sandy sediments of the Andaman and Nicobar insular margin. The major feature distinguishing P. atrovitta from other species of the genus Prionospio is the presence of well-marked black pigmented band near the anterior dorsal margin of the prostomium and pigmentation on the caruncle in the adults.