Calcareous sponges from New Caledonia Author Borojevic, Radovan Departamento de Histologia e Embriologia, Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Caixa Postal 68021, 21941 - 970 Rio de Janeiro (Brazil) radovan @ iq. ufrj. br radovan@iq.ufrj.br Author Klautau, Michelle Federal de Ensino Tecnologico de Quimica, Unidade de Rio de Janeiro, Senador Furtado 121 / 125, Maracana, 20270 - 021 Rio de Janeiro (Brazil) text Zoosystema 2000 22 2 187 201 journal article 10.5281/zenodo.5399987 1638-9387 5399987 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.

zation. They are supported by minute equiangular and equiradiate triactines and tetractines. The radial canals open into the central exhalant cavity or atrium, surrounded by a thin membrane that contains minute parasagittal triactines, which occasionally develop a fourth actine that is perpendicular to the atrial surface and points free into the atrial cavity.
Spicules (Fig. 3) Cortical triactines are equiangular and
equiradiate, with actines measuring 465 (± 160) / 47 (± 18) µm. Cortical tetractines are similar but larger: 890 (± 265) / 72 (± 20) µm. Small choanosomal triactines and the basal system of the tetractines are equiangular and equiradiate, or	FIG. 4. — Leucascus neocaledonicus n. sp. Spicules of the cormus. The arrow indicates the larger triactine of the external surface, the arrow head indicates tetractines of the internal tubes with a thin apical actine. Scale bar: 30 µm.
parasagittal when located in the periatrial	memGenus Leucascus Dendy, 1892
brane, and measure 50 (± 16) / 3.6 (± 1.2) µm.	TYPE SPECIES. — Leucascus simplex Dendy, 1892 by subsequent designation (Dendy & Row 1913).
REMARKS Leucaltis clathria has been reported from all the tropical seas, and the described specimens are morphologically quite homogenous. Recent	stuDIAGNOSIS. — Leucascidae with copiously branched and anastomosed choanocyte tubes. The exhalant aquiferous system is represented by a well-developed atrium delimited by a specific wall with no choanoderm.
dies on genetic characteristics of sponge populations have questioned the taxonomic value of the supposedly cosmopolitan sponge species (Solé-	Leucascus neocaledonicus n. sp. (Fig. 4)
Cava et al. 1991; Boury-Esnault et al. 1999). In contrast to many other Calcarea , L. clathria has a	TYPE MATERIAL. — Holotype MNHN-LBIM-C- 1999-02
very characteristic external morphology, a particular body wall organization, and several well-characterized spicule types. Consequently, L. clathria may be an interesting model to address the question of the cosmopolitanism by an extensive morphological and genetic analysis comparing populations from distant regions.	ETYMOLOGY. — Refers to the type locality, New Caledonia. MATERIAL EXAMINED. — Several large specimens from localities 114 and 1376. TYPE LOCALITY. — Canal Woodin, stn 1376. LOCALITIES. — Banc Gail, stn 114, 35 m. – Canal Woodin, stn 1376, 26-36 m.
Family LEUCASCIDAE Dendy, 1892
DIAGNOSIS. — Clathrinida with a body differentiated into a cortex and a choanosome whose organization is reminiscent of a clathroid body composed of anastomosed tubes. The cortex contains a specific skeleton composed of triactines and/or tetractines. Choanocyte chambers are tubular, often highly ramified and anastomosed. The choanoskeleton is restricted to the walls of the choanocyte chambers, maintaining a distinctly tubular organization.	DESCRIPTION The collection contains several large specimens which can attain a height of up to 8 cm. Their body is hard, lobate, flattened and irregularly folded (photo in Lévi 1998: 76). The external surface is smooth, white, pierced by very small ostia opening into elongate inhalant chambers. The body wall is approximately 2 mm thick in the

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