Aspidosiphon laevis

Aspidosiphon (Paraspidosiphon) laevis De Quatrefages, 1865

Languages: English

Overview

General Description

This species has only compressed unidentate hooks arranged in rings, well defined anal and caudal shields with extensive grooves or furrows, and two retractor muscles united for most of their length. Aspidosiphon laevis is a widespread species, but is usually present in low densities in tropical shallow waters.

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

This species has only compressed unidentate hooks arranged in rings, well defined anal and caudal shields with extensive grooves or furrows, and two retractor muscles united for most of their length Aspidosiphon laevis is a widespread species, but is usually present in low densities in tropical shallow waters.

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

Type

Type Locality

According to Saiz Salinas (1984) the vial containing the type in the Museum of Paris has 3 labels all listing the type locality as Mer des Indes (old French name for Indian Ocean); however, De Quatrefages (1865) in his description of the species reported that those specimens were provided by Mr. Quoy and Mr. Gairmard without any reference to the original collecting place. Saiz Salinas (1984) considers the type locality as unknown.

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

According to Saiz Salinas (1984) the vial containing the type in the Museum of Paris has 3 labels all listing the type locality as Mer des Indes (old French name for Indian Ocean); however, De Quatrefages (1865) in his description of the species reported that those specimens were provided  by Mr. Quoy and Mr. Gairmard without any reference to the original collecting place. Saiz Salinas (1984) considers the type locality as unknown.

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

Type Material

Holotype at Museum National d'Histoire Naturelle, Paris (MNHN): A’ (R) 1868. Nº 427a (Saiz Salinas, 1984). Saiz Salinas (1984) reported one specimen not-previously dissected. 

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

Holotype at Museum National d'Histoire Naturelle, Paris (MNHN): A’ (R) 1868. Nº 427a (Saiz Salinas, 1984). Saiz Salinas (1984) reported one specimen not-previously dissected. 

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

Description

Morphology

(From Cutler 1994, Saiz Salinas 1984)

External anatomy

Introvert commonly approximately as long as the trunk.

Tentacles up to 24 surround the nuchal organ. They are short and fused laterally.

On the distal introvert compressed unidentate, sharply, pointed or blunt hooks are arranged in many rings. The height of the hook (20-80 µm) is correlated with trunk length. Some scattered compressed hooks are present.

The anal shield is solid with 10-15 longitudinal grooves.

The caudal shield is conical and grooved. Saiz Salinas (1984) described 24 radial grooves for the type material.

 

Internal anatomy

The trunk wall has 25-35 longitudinal muscles bands, which often anastomose and usually can be seen through the trunk wall. The circular muscle layer is subdivided in bands, but these are not always distinct.

Intestine attached anteriorly and posteriorly by spindle muscle. A distinctive feature of the latter structure is the bifurcation near its anterior end. The contractile vessel of many specimens has vesicular pouches or swellings along the portion united with the retractors.

Rectal caecum present and can be single or complex with lateral branches.

Nephridia are usually more than half of the trunk length.

A pair of retractor muscles, fused for most of their length, originates in front of the caudal shield about 65-80% of the distance towards the posterior end of the trunk.

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

(From Cutler 1994, Saiz Salinas 1984)

External anatomy

Introvert commonly approximately as long as the trunk.

Tentacles up to 24 surround the nuchal organ. They are short and fused laterally.

On the distal introvert  compressed unidentate, sharply, pointed or blunt hooks are arranged in many rings. The height of the hook (20-80 µm) is correlated with trunk length. Some scattered compressed hooks are present.

The anal shield is solid with 10-15 longitudinal grooves.

The caudal shield is conical and grooved. Saiz Salinas (1984) described 24 radial grooves for the type material.

 

Internal anatomy

The trunk wall has 25-35 longitudinal muscles bands, which often anastomose and  be usually can be seen through the trunk wall. The circular muscle layer is subdivided in bands, but these are not always distinct.

Intestine attached anteriorly and posteriorly by spindle muscle. A distinctive feature of the latter structure is the bifurcation near its anterior end. The contractile vessel of many specimens has vesicular pouches or swellings along the portion united with the retractors.

Rectal caecum present and can be single or complex with lateral branches.

Nephridia are usually more than half of the trunk length.

A pair of retractor muscles, fused for most of their length, originates in front of the caudal shield about 65-80% of the distance towards the posterior end of the trunk.

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

Size

Haldar (1991) reported one worm measuring 138 mm in length by 42 mm width.

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

Haldar (1991) reported one worm measuring 138 mm in length by 42 mm width.

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

Ecology and Distribution

Distribution

(From Cutler, 1994)

Commonly present in low densities in tropical waters, this species is considered to be widespread. There are records in the Indo-West Pacific from Durban to Red Sea, in the Andaman Island, Malaya to southern Japan, Indonesia, the Great Barrier Reef, and islands east to Hawaii. It is also present in the western Atlantic Ocean from the 20ºS to 31ºN, the Caribbean, and in the eastern Atlantic from Canary and Cape Verde islands to the Gulf of Guinea.

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

(From Cutler, 1994)

Commonly present in low densities in tropical waters, this species is considered to be widespread. There are records in the Indo-West Pacific from Durban to Red Sea, in the Andaman Island, Malaya to southern Japan, Indonesia, the Great Barrier Reef, and islands east to Hawaii. It is also present in the western Atlantic Ocean from the 20ºS to 31ºN, the Caribbean, and in the eastern Atlantic from Canary and Cape Verde islands to the Gulf of Guinea.

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

Habitat and Ecology

(From Cutler, 1994)

This species is an inhabitant of coral rubble in shallow waters.

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

This species is an inhabitant of coral rubble in shallow waters.

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.
Haldar, B. P. (1991).  Sipunculans of the Indian coast. Memoirs of the Zoological Survey of India. 17, 1-169.
Saiz Salinas, J. I. (1984).  Los tipos de Sipunculidos de de Quatrefages del Museo de Paris. Bilbao: Universidad del Pais Vasco.