Baseodiscus mexicanus

Baseodiscus mexicanus

Biological Flags

  • Ecosystem: Marine
Languages: English

Overview

General Description

(from Coe, W. R. (1905).  Nemerteans of the west and northwest coasts of America.. Bull. Mus. comp. Zool. Harv.. 1-318)
This species occurs very abundantly on the west coasts of Panama and Mexico, and at the Galapagos Islands, but has not been found elsewhere. It belongs to that group of the genus having slender bodies which do not contract to any excessive amount when disturbed or killed. The worms reach a considerable size, those one or two meters long and 5-7 mm wide being common. Specimens in collections often measure at least half a meter in length. In shape the body is slender, flattened when strongly contracted, largest just back of head; intestinal region broad and flat; posterior extremity very slender. Snout of moderate size, distinctly marked off from posterior portion of head by conspicuous lateral transverse grooves which form an annular constriction when contracted. Ocelli numerous, situated in an elongated cluster on each lateral border of snout.

Description

External Appearance

(from Coe, W. R. (1905).  Nemerteans of the west and northwest coasts of America.. Bull. Mus. comp. Zool. Harv.. 1-318)
Dark brown, with very numerous fine white rings encircling the body at irregular intervals throughout its whole length. Some of the rings are very much finer than others, and many are more or less broken and incomplete. A large specimen has several hundred of these rings, which remain sharp and conspicuous after the worms have been kept in alcohol for many years. Snout bordered laterally and anteriorly by narrow horizontal white band, which passes through or immediately above terminal proboscis pore and joins the first white ring, which occurs at junction of snout to posterior portion of head. White rings commonly 1 mm or less in breadth, while alternating brown bands arc about 3 mm wide in moderate extension, but are considerably narrower than diameter of body.

Ecology

Habitat

(from Coe, W. R. (1905).  Nemerteans of the west and northwest coasts of America.. Bull. Mus. comp. Zool. Harv.. 1-318)

The species has previously been reported from the west coasts of Panama and Mexico, and from the Galapagos Islands (Buerger, 1893). A number of large specimens were collected by Mr. Alexander Agassiz and by the Hassler expedition on the west coast of Panama. Several large specimens in the Yale Museum were collected in the same region by Mr. Bradley and another lot by Mr. McNeil. It is apparently the largest and most abundant nemertean found in that region.