Sipunculus (Sipunculus) lomonossovi Murina, 1968
Sipunculus lomonossovi has a transparent body wall and lives in deep cold waters. This species was described based on one specimen and has a questionable status according Cutler and Cutler (1985). It is similar to two other congeneric species S. nudus and S. novergicus but they are separated by differences in internal characteristics such as brain shape and numbers of LMBs and in their differing habitats.
S. nudus has the same number of LMBs but differs in habitat and shape of the brain. S. novergicus differs in the number of LMBs and brain shape, but may occur at similar depths (Cutler 1994).
(From Murina, 1968; Cutler, 1994)
External anatomy
Body wall is transparent.
Glans region (a smooth posterior tip) is indistinctly set off.
Internal anatomy
28-34 longitudinal muscles bands (LMBs) are flat and thin. The LMBs continue as distinct undivided bundles at the glans region, but circular muscles are continuous.
A pair of nephridia with irregular rough surface, partially attached to the trunk wall.
The brain is rounded, single lobed, without elongate digitate processes.
Up to 110 mm long (Cutler, 1994).
Found in cold deep waters (2500-4300 m), from the far South Pacific, eastern Atlantic (20-34º N), and off Brazil (Murina, 1968; Cutler, 1994).
The sediment of the holotype locality was silt and foraminifera ooze (Murina, 1968).