Lissoclinum calycis Monniot, 1992

Kott, Patricia, 2005, New and little-known species of Didemnidae (Ascidiacea, Tunicata) from Australia (Part 3), Journal of Natural History 39 (26), pp. 2409-2479 : 2461

Lissoclinum calycis Monniot, 1992

( Figure 21E )

Lissoclinum calycis Monniot 1992, p 568 ; Kott 2001, p 301; 2004c, p 40.

Distribution

Previously recorded (see Kott 2001): Queensland (Heron I.); New Caledonia. New record: Northern Territory (QM G308749).

Description

In life, the colony is a thin, delicate, transparent sheet closely adhering to the rubble that it is growing over and that is embedded in the test. Clumps of small zooids are embedded in the test. Spherical larvae with four almost spherical, stalked epidermal ampullae, each with a terminal cap of columnar cells, are along each side of the antero-median adhesive organs, which also have unusually long stalks. A patch of three-dimensional tetrahedral spicules made up of many fine crowded needle- or rod-like rays are in a patch between the ventral flexure of the abdomen and the ventral border of the thorax. The crowded needle-like rays progressively increase in length but simultaneously become fewer along each of the arms to form the terminal points.

Remarks

With the exception of the absence of a complete capsule of spicules around the abdomen, the specimen agrees with previous accounts of the species. It appears that the extent to which this capsule is complete may vary within the species. Similarly, though both the western Pacific Lissoclinum ravarava C. and F. Monniot, 1987 (see Kott 2001, p 295) and L. limosum Kott, 2001 are known to have a group of spicules between the abdomen and the ventral border of the thorax they are distinct species with significant differences in spicules, colonies, and larvae. Significant differences also exist between L. abdominale: Monniot, 1992 and the nominal species from Guadaloupe, which Monniot (1992) thought were conspecific on the basis of their similar clumps of spicules. The temperate species L. tasmanense Kott, 2001 (distinguished from the tropical species referred to above by the spicule shape and a distinctive larva) also has similar clumps of spicules. There appears not to be any phylogenetic significance attached to these clumps, intraspecific variation in spicule distribution around the abdomen in certain species sometimes resulting in an abdominal capsule of spicules.

That the present species is seldom recorded probably is the result of its inconspicuous appearance and delicacy of the colony.

Figures

Figure 21. In situ images of: (A) Trididemnum amiculum (SAM E3263); (B) Trididemnum nobile (SAM E3262); (C) Trididemnum pigmentatum (QM G308714); (D) Trididemnum savignii (QM G308721); (E) Lissoclinum calycis (QM G308749); (F) Lissoclinum clavatum (SAM E3260, holotype); (G) Lissoclinum concavum (SAM E3242); (H) Lissoclinum levitum (SAM E3254).