Phascolion convestitum

Phascolion (Isomya) convestitum Sluiter, 1902

Languages: English

Overview

General Description

In this species the anus is at the anterior end of the trunk and holdfast papillae are usually variable. Hooks are broad-based, recurved and pointed. Dorsal retractor muscle is slightly larger than the ventral muscle.

Author(s): Kawauchi, Gisele Y.
Rights holder(s): Kawauchi, Gisele Y.

Type

Type Locality

Malaya, Siboga station 105, 275 m (Stephen and Edmonds, 1972).

Author(s): Kawauchi, Gisele Y.
Rights holder(s): Kawauchi, Gisele Y.

Type Material

Zoologisch Museum, Universiteit van Amsterdam, Amsterdam, ZMUA, Sluiter’s type-material, V.SI 48-2, 48-3.

Author(s): Kawauchi, Gisele Y.
Rights holder(s): Kawauchi, Gisele Y.

Description

Morphology

(From Cutler and Cutler, 1985; Cutler, 1994)

 

External anatomy

Hooks with broad base, recurved and pointed (50-100 µm tall).

Holdfast papillae from large and bulbous to small and compact. Some have granular material around the border as a distinct unit, others are without hardened material, others have a smooth and slightly darker border.

Tentacular crown consists of 20-25 normal tentacles.

Anus at the anterior end of the trunk.

 

Internal anatomy

Dorsal retractor slightly larger than ventral .

Dorsal retractor with single origin.

Ventral muscle with two origins, which straddle the ventral nerve cord near its posterior end.

Esophagus may be connected to the dorsal retractor muscle.

Intestine in loops with few loose coils.

Short and strong fixing muscle at the posterior end of the coil, attaching it to the trunk wall between the roots of the ventral retractor muscle (this is not a spindle muscle).

Author(s): Kawauchi, Gisele Y.
Rights holder(s): Kawauchi, Gisele Y.

Similar Species

According to Cutler and Cutler (1985) P. convestitum is similar to P. tuberculosum in many ways. They suggested that the former species may only deserve subspecific rank, but they did not propose any change for P. convestitum.

Author(s): Kawauchi, Gisele Y.
Rights holder(s): Kawauchi, Gisele Y.

Ecology and Distribution

Distribution

Mediterranean, Red Sea, Gulf of Aden and Indonesia (Cutler, 1994).

Author(s): Kawauchi, Gisele Y.
Rights holder(s): Kawauchi, Gisele Y.

Habitat and Ecology

From 25-275 m (Cutler, 1994).

Author(s): Kawauchi, Gisele Y.
Rights holder(s): Kawauchi, Gisele Y.

References

Cutler, E. B. (1994).  The Sipuncula. Their systematics, biology and evolution. 453 pp. Ithaca, N.Y.: Cornell University Press.
Cutler, E. B., & Cutler N. J. (1985).  A revision of the genera Phascolion Theel and Onchnesoma Koren and Danielssen (Sipuncula). Proceedings of the Biological Society of Washington. 98, 809-850.