Leucascus neocaledonicus Borojevic & Klautau, 2000

Cavalcanti, Fernanda F., Rapp, Hans Tore & Klautau, Michelle, 2013, Taxonomic revision of Leucascus Dendy, 1892 (Porifera: Calcarea) with revalidation of Ascoleucetta Dendy & Frederick, 1924 and description of three new species, Zootaxa 3619 (3), pp. 275-314 : 287-289

Leucascus neocaledonicus Borojevic & Klautau, 2000

Diagnosis: Cortical membrane with mainly triactines. Skeleton of the choanocyte tubes with the same proportion of triactines and tetractines. Atrial skeleton composed mainly of triactines. Tubes are mainly hispid.

Synonymies: Ascaltis grisea : Lévi 1998: 76; Leucascus neocaledonicus: Borojevic & Klautau 2000: 191 ; Ascaltis sp. 2: Wörheide et al. 2004: 819; Leucascus sp.: Dohrmann et al. 2006: 832.

Type material: MNHN-LBIM-C-1999-02 and UFRJPOR 5033 (Holotypes—two fragments of the same specimen—Canal Woodin, station 1376, New Caledonia; depth: between 26 and 36 m).

Type locality: Canal Woodin, New Caledonia.

Additional analysed material: UFRJPOR 5026 (Banc Gail, station 114, New Caledonia; depth: 35 m); UFRJPOR 5027 (Station 374, New Caledonia); UFRJPOR 5028 (Station 1216, New Caledonia); and QM G316051 (Great Barrier Reef, Australia).

Description: The colour of this sponge is white alive (Lévi 1998), becoming beige after fixation. The holotype consists of one fragment measuring 2.5 x 1.5 x 1.3 cm (MNHN-LBIM-C-1999-02) and several smaller fragments, measuring about 2.0 x 1.0 x 0.5 cm (UFRJPOR 5033). The body is massive, lobate ( Figure 7 A), and its consistency is firm. Oscula are localised at the top of elevations and have no ornamentation. The tubes are tightly anastomosed ( Figure 7 B).

The cortical membrane is thin and composed mainly of triactines, but some tetractines are also present ( Figure 7 C). In this region, the triactines are variable in size (both length and thickness). Inside, the skeleton of the tubes is formed by triactines and tetractines, apparently in the same proportion. The tetractines point their apical actine into the lumen of these tubes ( Figure 7 D). The atrial skeleton is composed of triactines and tetractines, where the triactines are more abundant than the tetractines ( Figure 7 E).

Spicules/ Specimens Actine Length (µm) Width (µm)

Min Mean SD Max Min Mean SD Max N

Triactine

MNHN-LBIM-C-1999-02 (H) 44.2 102.9 21.4 137.8 9.1 14.2 3.1 18.2 30

UFRJPOR 5026 80.6 106.7 14.8 132.6 9.1 12.7 2.4 16.9 30

UFRJPOR 5027 101.4 128.2 15.5 187.2 15.0 18.3 1.8 23.4 30

UFRJPOR 5028 98.8 131.2 19.6 169.0 11.7 15.2 2.4 19.5 30

All specimens 44.2 117.2 12.6 187.2 9.1 15.1 2.1 23.4 –

Tetractine Basal

MNHN-LBIM-C-1999-02 (H) 70.2 103.2 12.6 124.8 6.5 14.1 2.1 18.2 30

UFRJPOR 5026 80.6 102.1 8.1 114.4 10.4 12.1 1.0 14.3 30

UFRJPOR 5027 75.4 93.8 9.1 114.4 10.4 11.8 1.1 13.0 30

UFRJPOR 5028 83.2 108.0 9.5 122.2 9.1 12.8 1.4 16.9 30

All specimens 70.2 101.8 5.1 124.8 6.5 12.7 0.9 18.2 –

Apical

MNHN-LBIM-C-1999-02 (H) 41.6 45.2 3.0 49.4 3.9 4.4 0.1 5.2 0 5

UFRJPOR 5026 36.4 62.3 22.6 156.0 2.6 4.8 1.0 6.5 30

UFRJPOR 5027 39.0 71.0 29.1 140.4 3.9 5.8 1.4 9.1 30

UFRJPOR 5028 31.2 73.7 29.0 156.0 2.6 5.1 1.6 9.1 30

All specimens 31.2 63.1 11.1 156.0 2.6 5.0 0.5 9.1 – Spicules ( Table 5):

(i) Triactines ( Figures 7 F, 8A): Regular. Actines are conical, straight, with blunt tips. Their size is variable in the cortical membrane;

(ii) Tetractines ( Figures 8 A): Similar to the triactines. The apical actine is thinner and shorter than the basal ones, although sometimes it has the same length of them. It is ornamented with spines organized in rows ( Figure 8 B).

Remarks: Differently of the original description, we decided to consider only one category of triactines occurring in the choanosome and in the cortical and atrial membranes. In fact, the size of the triactines is variable in the cortical membrane, but is more uniform in the choanocyte tubes and in the atrial skeleton. The spines of the apical actine of the tetractines were not mentioned in the original description. They were more abundant in the specimen UFRJPOR 5027, but in all analysed specimens they were present, always organized in rows.

In addition to L. neocaledonicus three other species also have only one category of triactines and one of tetractines: L. roseus , L. simplex , and L. albus sp. nov. Despite this similarity there are important differences between them. Leucascus neocaledonicus differs from L. roseus by the colour, white in the former and pink in the latter, and also by the presence of tetractines as the main spicule type in the atrial skeleton of L. roseus . The most similar species to L. neocaledonicus is L. simplex . However, they can be distinguished by the higher abundance of tetractines in L. neocaledonicus . Leucascus neocaledonicus can be separated from L. albus sp. nov. mainly because of the presence of microdiactines in L. albus sp. nov.

Distribution: West Pacific Ocean: Canal Woodin and Banc Gail—New Caledonia (Borojevic & Klautau 2000); Great Barrier Reef—Australia (Wörheide et al. 2004; Dohrmann et al. 2006). Spalding et al. (2007) corresponding ecoregions: New Caledonia, Torres Strait Northern Great Barrier Reef, and Central and Southern Great Barrier Reef.

Figures

FIGURE 7. Leucascus neocaledonicus (MNHN-LBIM-C- 1999 - 02, holotype). A, Preserved specimen; B, Transverse section showing the cortex (ct), choanocyte tubes, and atrium (at); C, Cortical membrane; D, Apical actines projected into the lumen of a tube; E, Atrial membrane; F, Triactine.

FIGURE 8. Leucascus neocaledonicus (MNHN-LBIM-C- 1999 - 02, holotype). A, Triactine (left) and tetractine (right); B, Apical actine of a tetractine (SEM).