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Clio piatkowskii Van der Spoel, Schalk and Bleeker, 1992

Overview

This species is a extremely broad pyramidal shelled deep-sea snail, 1.4 cm long. Its shell is transparent, the wings are black. The wings are large and thick fleshy, while the posterior footlobe is small. The lateral sides are sharp and not gutter-shaped. Besides growth lines, there is a wavy transverse structure in the shell. It is only recorded from the Weddell Sea, although its distributions is supposed to be the deep-sea of the southern oceans (Clio piatkowskii drawing).

Taxonomic Description

Clio piatkowskii (Clio piatkowskii) has an opaque shell. The lateral sides are sharp, not gutter-shaped, but with small irregularities on the edge due to imbricate protrusions of growth lines. The lateral sides are strongly diverging, the top angle is about 70° which is more than in any of the other species of the genus, except for Clio cuspidata. The posterior part of the lateral sides is concave, the anterior part is convex. Both ventral and dorsal side show strong wave-like transverse striae, which near the apex are smaller and more narrowly spaced. The ventral side is slightly curved and provided with one central longitudinal rib. The curved dorsal side has three such ribs. The transverse section through the shell is narrow, oval, and slightly asymmetrical as the dorsal side is vaulted higher than the ventral side. (Clio piatkowskii dorsal view, Clio piatkowskii lateral view).
The soft parts have all the characters of a deep-sea thecosome: fleshy wings (Clio piatkowskii wings) and posterior footlobe, dark purple footlobe and lips, brown hue over the wings, large dorsal tentacles and the right one has a sheath. The size of the posterior footlobe is, compared to other deep-sea Thecosomata relatively small. The mantle gland consists of two narrow bands of cuboid cells and two very broad bands of zigzag cells. The radula formula is 1-1-1. The dentation on the median plate is strong.
Shell length is 13.5 mm, its width is 16 mm.

Morphology and Structure

In Clio piatkowskii the whole muscle system is strongly developed (Clio piatkowskii wing muscle). The columellar muscle is much larger than in any other Clio species and the thick muscles in the wings suggest that the species is a quick swimmer also the animals seems unable to retract completely in its relatively small shell and the long neck region keeps the wings almost free from the shell aperture. In the neck region at the wing base a well developed cartilaginous-like connective tissue is found giving the area strength. The mantle gland shows 6 bands one of these is very small in the middle (Clio piatkowskii mantle).

Juveniles

The Clio piatkowskii protoconch I is blunt and continuous with protoconch II and teleoconch without any visible border. There are some irregular longitudinal lines on the embryonic shell. The sharp lateral ribs begin directly above the protoconch II.

Reproduction

Clio piatkowskii is a protandric hermaphrodite and ovoviviparous. Eggs are found in different stage of development in different folds of the accessory sexual gland (Clio piatkowskii reproduction). The different developmental stages of eggs and larvae are kept separate in different folds of the accessory sexual gland. The ovoviviparity in this species is well developed. The small gonad contains ripe ova and sperm, consequently self-fertilisation is not impossible. The succession of male and female phase, which are separate stages in most Clio species, may be lost as both male and female products are present in equal quantities.

Ecology

The intestine and gizzard of Clio piatkowskii were found filled with diatoms and a few Foraminifera suggesting that feeding took place near the surface in the upper 100m. The species is an omnivore feeding on diatoms, foraminiferans, radiolarians, and its occurrence is meso- to bathypelagic.

Distribution

Clio piatkowskii shows a vertical distribution; during day time being found near the bottom and at night from 100m to the bottom. A daily migration over about 1000m probably occurs. It is found in the Weddell Sea, see the Clio piatkowskii map.

Types

Clio piatkowskii Van der Spoel, Schalk and Bleeker, 1992: 2, fig. 1.
Holotype (ZMA. 389028) 1 paratype (ZMA. 389029).
Type locality: Epos ANT. VII, 4, St. 262, 10-2-1989, RMT(1+8); 600-1000 m depth, 74°31.1'S 29°20.3'W, bottom depth 1200 m and: Epos ANT. VII, S4, St. 260, 10-2-1989, B.P. Trawl; 5666-690 m depth, 74°39.29'S 29°36.50'W, bottom depth 700 m. Type locality: Weddell Sea.

Clio piatkowskii