Pyura scortea Kott, 1985

Kott, Patricia, 2008, Ascidiacea (Tunicata) from deep waters of the continental shelf of Western Australia, Journal of Natural History 42 (15 - 16), pp. 1103-1217 : 1205

Pyura scortea Kott, 1985

( Figure 15E )

Pyura scortea Kott 1985, p. 324 . Monniot C. 1989, p. 487.

Distribution

Previously recorded (see Kott 1985; Monniot 1993): Western Australia (Cockburn Sound); New Caledonia. New record: Western Australia CSIRO 10/05 (Point Cloates, Stn 140, 355 m, QM G328138).

The newly recorded specimen is only the third record of this species.

Description

The specimen is about 3 cm long and almost as wide, but tough, wrinkled, furrowed and contracted and probably larger and with a smooth outer surface when not so strongly contracted. Both apertures are comspicuous, the branchial aperture terminal and the atrial aperture on a siphon projecting forward from about halfway down the dorsum. Minute (0.02 mm) flat, overlapping scales, convex around their anterior free margin, line both branchial and atrial siphons. The dorsal tubercle is in the short mid-dorsal peritubercular V at the anterior end of the row of dorsal languets along the dorsal midline. Seven well-formed branchial folds are on each side of the body. The gut loop is narrow and gently curved just above the endostyle on the left side of the body. An arborescent liver with crowded lobules branches off the pyloric region of the gut. Gonads are of the usual form for this genus, being divided into a row of connected hermaphrodite blocks. The left gonad is in the loop of the gut and the right one in a corresponding position on the right side of the body. Endocarps are on both the gonads and the gut loop.

Remarks

The present species is distinguished by its tough and usually wrinkled test, by the position of the atrial siphon halfway down the body, and by its rounded siphonal scales, shallow peritubercular V, narrow, only slightly curved gut loop and endocarps on the gut loop. Many species in this genus have a tough leathery test and, having strong body muscular they are particularly contractile. Their external appearance does not give many clues to their identity. Further, many are cryptic and strongly adhere to the substrate and are not often collected.

Like Microcosmus , the genus Pyura has siphonal armature (rounded scales or pointed spines) on the portion of test that turns in to line siphons. Scales similar to the present ones are known in Pyura abradata Kott, 1985 , P. confragosa Kott, 1985 , P. crassacapitata Kott, 1985 , P. elongata Tokioka, 1952 , P. fissa ( Herdman, 1881) , P. irregularis ( Herdman, 1882) , P. molguloides ( Herdman, 1899) and P. navicula Kott, 1985 as well as P. scortea . With the exception of P. molguloides and P. scortea (which have narrow loops in the ventral curve of the body), the gut of each of these species (especially the first three) forms an open D-shaped loop that occupies a great part of the left body wall. Pyura molguloides , P. fissa and P. irregularis are also distinguished by their deep, narrow peritubercular Vs that extend about halfway down the dorsal midline of the branchial sac. Pyura abradata , P. elongata and P. molguloides lack endocarps on the gut. Pyura molguloides is also distinguished by its unusual sandy coat and P. abradata is unique in having nine branchial folds on each side.

Figures

Figure 15. Cnemidocarpa completa (QM G328141): A, external view; B, internal view, right side showing branchial sac cut away to display gonads. Stolonica aluta (QM G328460): C, external view of a single zooid; D, pallial wall showing gut and gonads on left side. Pyura scortea (QM G328138): E, external view. Molgula elva sp.nov. (WAM Z27525): F, detail of branchial infundibula; G, internal view showing body organs and muscualture. Scales: A, E, 0.5 cm; B–D, 0.2 cm; F, 0.5 mm; G, 1 mm.