Sipunculus (Sipunculus) longipapillosus Murina, 1968
Elongate papillae in the middle of the trunk distinguish this species from other congeners, but it can be confused with Xenosiphon branchiatus, which has similar elongate papillae in the same trunk region. However, the elongate papillae in S. longipapillosus are arranged in longitudinal rows, whereas those in X. branchiatus are diagonal.
Sipunculus longipapillosus may be confused with Xenosiphon branchiatus because both have elongate papillae in the middle of the trunk region, but S. longipapillosus is distinguished by the longitudinal arrangement of the elongate papillae, the absence of the protractor muscles, the unattached nephridia opening posterior to the anus, and the spindle muscle originating from the trunk wall anterior to the anus. (Cutler, 1994).
(From Cutler and Cutler, 1979; Cutler, 1994)
External anatomy
Elongate papillae in the middle third of the trunk are arranged in longitudinal rows and extend from the coelomic canals between the LMBs. The papillated region ranges from 30-75% of the trunk, covering about 50%.
Internal anatomy
24-30 longitudinal muscles bands (LMBs), usually 27-29 LMBs, double in number in the posterior end of the trunk.
A pair of nephridia unattached to the trunk wall opening posteriorly to the anus.
Spindle muscle originates from the trunk wall anterior to the anus.
Brain is without digitate processes.
This species was recorded from the Red Sea and northwestern Indian Ocean, at 60 – 370 m (Cutler, 1994).