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Orthoporidra compacta

Geographic Distribution

Antarctic Convergence illustration Antarctic convergence

Bathymetric Specimen Dispersal

55 individual specimens found for Orthoporidra compacta.

Orthoporidra compacta   Species


Original Description
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Original Description
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"Orthopora compacta sp. nov.

(Pl. V, figs. 4a-i)

This is allied to Turritigera, in having the ovicell situated proximally to the oral aperture, which is the most distinguishing character of T. stellata B., although it was not appreciated when first described, for the « tumid prominence » referred to by Busk is the ovicell. The zoarium is erect branching, cylindrical. The zooecia are porcellanous, inflated; and above the oral aperture there is a long process bearing an avicularium, with a triangular mandible. The calcareous tube leading from the avicularium is very distinctly seen when the avicularian process is broken away. In many Celleporae the avicularian tubes are in the wall of the zooecia or peristome, but here they form a projection into the peristome, and the same structure is seen in Turritigera stellata B.

The operculum is straight below, and the muscular attachments are quite at the distal end (fig. 4b) so that from the position of the muscular attachments it could be distinguished from all other species, with which I am acquainted. There are occasionally on the surface of the zooecium one or two small triangular avicularia, also sometimes two similar ones on the ovicell, and they may occur on the oral avicularian process. There are a few vicarious avicularia with spatulate mandibles. Sections show a marked peculiarity in the tentacular sheath, which in most species is quite thin, showing a few nuclei at intervals, as figured by CALVET, LEVINSEN, and others but in O. compacta it is three or four times the usual thickness, and shows the darkly stained longitudinal muscular band. The parenchym, with nucleated cells is found on each side of the sheath. The sheath of Cellepora bispinata B. is also very thick.

There are 24 tentacles and no oral glands were found. In Lagenipora granum Hincks there are 12 tentacles ; in Cellepora umicosa B. 15-20 ; in C. caminata Waters 16; in C. sardonica Waters 13; in C. verruculata Sm. 14; in C. incrassata Sm. 17; in C. ventricosa Lorenz 21; in Osthimosa evexa Jull. there are 10 (fide JULLIEN); in Lagenipora Costazii Aud. 12; in Cellepora bispinata B. there are 16; in Osthimosia clavata nov. 18; C. horneroides nov. 18-20. The O. compacta is very similar to Cellepora solida Busk, and at first was thought to be identical, but upon an examination of the British Museum CHALLENGER specimen, the operculum was found to have a different shape (see Pl. V, fig. 5). BUSK calls the operculum suborbicular, and figures it as Pl. XXIX, fig. 12a, but nothing of the kind is found in Busk's preparation, whereas there are several opercula as given in my figure 5. Some mistake has been made in the « Challenger Report » which I have not fathomed.

From the Cape Horn Expedition, Dredge, No 32, Lat. 53° 13' S.- Long. 68° 3i' W., 97 met., +6°.6 C., there are specimens of Cellepora growing from a very small base, which gradually becomes wider, making the colony club-shaped. The growth and appearance is so similar to that of Orthopora compacta, that I had no doubt as to its being the same, until I made preparations, and then the operculum showed, that in the aperture there was a wide round sinus, further the mandible is characteristic, having a very narrow, elongate lucida. The lower edge of the aperture frequently appears straight, which is difficult to understand, as the lower edge of the operculum always has the round projection, but the sinus of the aperture must be concealed by calcareous growth in front of it. Sections show that there are only 13 to 14 tentacles in the Cellepora under consideration, whereas 0. compacta has 24. The Cape Horn specimen will probably be called C. petiolata nov.

HABITAT. - Exp. Antarct. Belge.

No 343, Tangles IV. Lat. 71º 18' S.- Long. 88º 02' W.;435 met.; —0.3 C.

No 428, Tangles VI. Lat. 71º 19' S.- Long. 87º 37' W. ;436 met.; -0.2 C.

No 613, Tangles VIII. Lat. 70º 00' S.- Long. 80º 48' W.; 500 ? met.; +0.9 C." (Waters, 1904: 75-6)

Geographic Distribution

Exp. Antarct. Belge. Tangles IV, VI, VIII


Displaying 10 of 55 Specimens

Type Status Catalog No. Date Collected Location Coordinates Depth (m) Vessel
  17505 3/15/1964 Antarctic Ocean 62.7° S , 54.7° W 265 Eltanin R/V
  17506 1/28/1972 Antarctic Ocean 64.8° S , 64.12° W 100 Hero R/V
  17507 2/23/1972 Antarctic Ocean 64.79° S , 64.11° W 73 – 128 Hero R/V
  17508 2/23/1981 Antarctic Ocean 64.79° S , 64.11° W 100 – 110 Hero R/V
  17509 2/16/1976 Scotia Sea 60.47° S , 46.45° W 115 – 132 Islas Orcadas R/V
  17510 2/17/1976 Scotia Sea 60.5° S , 46.71° W 128 – 130 Islas Orcadas R/V
  17523 5/31/1975 Scotia Sea 56.74° S , 27.05° W 137 – 155 Islas Orcadas R/V
  17524 2/10/1969 Antarctic Ocean 64.9° S , 62.2° W 119 – 124 Hero R/V
  17525 2/10/1974 Antarctic Ocean 66.9° S , 163.3° E 55 – 146  
  17526 12/13/1961 Antarctic Ocean 66.37° S , 110.5° E 293 – 329 Wilkes Station R/V

Displaying 10 of 55 Specimens

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