Leucaltis clathria Haeckel, 1872

Borojevic, Radovan & Klautau, Michelle, 2000, Calcareous sponges from New Caledonia, Zoosystema 22 (2), pp. 187-201 : 190-192

Leucaltis clathria Haeckel, 1872

( Figs 2; 3 )

Heteropegma nodus gordii Poléjaeff, 1883.

MATERIAL EXAMINED. — Several large specimens from localities R-1234 and R-1356.

LOCALITIES. — South coast, Canal Woodin, R-1234, 40 m. – Banc Gail, R-1356, 22 m.

DESCRIPTION

The specimens of L. clathria from New Caledonia are large, composed of ramified firm and friable tubes ending with wide oscula without the perioscular crown. The surface is smooth, shiny and rough, due to large cortical spicules (photo in Lévi 1998: 75).

The organization of the sponge body is typical of the genus. The cortical skeleton which is very thick, is supported by large triactines and the basal system of giant tetractines ( Figs 2; 3 ). The choanosome is composed of rather irregular tubes, which maintain the general radial organi- upper parts, and can reach 4 mm in the basal parts. It surrounds a wide flattened central atrium, whose surface is pierced by large oval exhalant cavities. Inside the sponge wall, each cavity divides into several channels that run perpendicularly to the atrial surface. The surface of exhalant cavities is hispid due to the presence of the long apical actines of tangential tetractines. The surface of the main atrial cavity is smooth or only slightly echinated by short apical actines of atrial tetractines. The choanosome is composed of tubes, radially arranged at the distal part, and somewhat irregular in the proximal one, where they open into the exhalant canals and cavities.

The cortical skeleton is very thin and contains triactines that are barely larger than those of the choanosomal tubes. The skeleton of the tubes is also composed of triactines, some of which have a short and thin apical actine (Fig. 4). The exhalant canals have triactines and tetractines whose long and thin apical actines reach the central part of the lumen. On a transverse section, the choanosome contains a dense regular radial network of choanocyte tubes, intercalated with smooth inhalant and hispid exhalant canals. The canals are all the same size, i.e. larger than the choanocyte tubes, and also maintain an approximately radial organization.

Spicules (Fig. 4)

Cortical triactines, equiangular and equiradiate, measuring 130 (± 27) / 12 (± 2.5) µm; choanosomal triactines, measuring 100 (± 14) / 10 (± 1.5) µm; tetractines with the basal actines of the same size, and the apical actine thinner than the basal ones, with a long thin distal part, often slightly curved.

REMARKS

The classification of large Calcinea that retain the organization of the choanosome as a dense network of tubes corresponding to the ascon tubes is quite complex. We proposed the retention of only the sponges that have a cormus composed of typical asconoid tubes, without a defined cortex or the exhalant aquiferous system devoid of the choanoderm in the family Clathrinidae (Borojevic et al. 1990) . Whilst the sponges of the genus Ascaltis have a cortex and, consequently, an inhalant aquiferous system, their central large tube or cavity that opens to the osculum is still covered by choanocytes, and hence they have no exhalant aquiferous system. Conversely, the genus Leucascus is characterized by the presence of a central exhalant cavity devoid of choanocytes, representing a true exhalant aquiferous system.In sponges that have not been properly preserved, this is not easy to see, and in older descriptions, attention has not always been given to these details. Consequently, Leucascus neocaledonicus is probably close to several of the large calcareous sponges described under the name Leucosolenia in the Indo-Pacific region, such as L. ventricosa Carter, 1886 , L. wilsoni Dendy, 1891 , L. pelliculata Dendy, 1891 and L. protogenes Haeckel, 1872 (sensu Dendy 1891). Leucosolenia ventricosa and L. pelliculata are characterized by large cortical triactines, and L. protogenes and L wilsoni have no tetractines. Leucosolenia grisea Dendy & Frederick, 1924 is quite similar to Leucascus neocaledonicus both in the general organization of the body and the skeleton, and in the preliminary study (in Lévi 1998) we included the sponges here described as L. neocaledonicus in Ascaltis grisea described by Dendy & Frederick (1924). However, these authors stated that in L. grisea the “tubes open into the main exhalant canals, which are also lined by basinucleate collared cells, and open to the exterior by true oscula”, indicating that this sponge belongs to the genus Ascaltis , whilst the specimens described here have a true atrial cavity. The same authors also described Ascoleucetta compressa Dendy & Frederick, 1924 that we now place in the genus Leucascus . This sponge is very similar to L. neocaledonicus and can be distinguished only by the presence of a rather thick cortex composed of two types of tangential triactines, and a particular fringe of trichoxea that guards the inhalant apertures.A comparative study of this species complex will be necessary to identify the possible synonymies and the geographical distribution of each species.

Family LEUCETTIDAE Laubenfels, 1936

Figures

FIG. 3. — Leucaltis clathria Haeckel, 1872. Spicules of the sponge wall. Note the giant tetractine and triactines of the cortex, minute triactines and tetractines present in the choanosomal skeleton and sagittal triactines in the membrane delimiting the central atrial cavity. Scale bar: 80 µm.