Leucascus clavatus Dendy, 1892

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 : 280-283

Leucascus clavatus Dendy, 1892

Diagnosis: Presence of club-shaped diactines perpendicular to the sponge surface. Apical actine of tetractines with well developed spines, and a ring at the base.

Synonymies: Leucascus clavatus Dendy 1892: 78 ; Dendy & Row 1913: 731; Brøndsted 1926 (?): 300; Row & Hôzawa 1931: 743; Burton 1963: 241.

Type material: BMNH 1893.6.9.2 and NMV F42333 (Holotypes—two fragments of the same specimen; near Port Phillip Heads, Australia; Wilson collection).

Type locality: Port Phillip Heads, Australia.

Additional analysed material: BMNH 1925.11.1.1727 (Port Phillip Heads, Australia; Dendy collection, R.N. 240), BMNH 1924.2.6.53 (Wilson collection), BMNH 1925.11.1.1726 (near Port Phillip Heads, Australia; R.N. 196), BMNH 1925.11.1.1728 (near Port Phillip Heads, Australia; R.N. 241), WAM Z40143 (Jack Reef, Dongara, Western Australia, 2918.85’S 11454.7’E; coll. J. Fromont, CS Whisson & GI Moore; 15.03.2006; depth: 6.5 m), WAM Z40519 (Jurien Bay, Julia Rocks, Western Australia, 30 09.34’S 114 59.83’E; coll. G. Clapin, R. Babcock & A. Sampey; 03/V/2005; depth: 5.6- 5 m), WAM Z40521 (Jurien Bay, Julia Rocks, Western Australia, 30 09.34’S 114 59.83’E; coll. G. Clapin, R. Babcock & A. Sampey; 03/V/2005; depth: 5.6- 5 m), and NMV F42334 (a fragment of BMNH 1925.11.1.1728).

Description: The colour of this species alive is unknown but after fixation it is beige ( Figure 3 A). The cormus is massive and its consistency is firm but compressible. The cormus is formed by anastomosed tubes covered by a thin and smooth membrane. The WAM specimens have a rounded shape ( Figure 3 A) and their surfaces are a little ridged. The osculum is single, large (ca. 7 mm in diameter in the specimens from WAM) and without ornamentation. The atrial cavity is also surrounded by a thin membrane, which was not observed in the specimen NMV F42333 , probably due to its preservation. Reproductive structures were found in the specimen BMNH 1924.2.6.53.

The skeleton is composed of diactines, triactines, and few tetractines. Diactines are present mainly near the osculum and their abundance varies from rich to rare among the analysed specimens. They lay mainly perpendicular to the surface ( Figure 3 B), but they can also be found below the cortical membrane ( Figure 3 C). These latter are rare and shorter than the protruding diactines. The skeleton of the cortical membrane is also composed of triactines and some rare tetractines ( Figure 3 D). These spicules are also present in the tubes ( Figure 3 E), where the tetractines project their apical actines into the lumen ( Figure 3 F). The atrial skeleton is composed exclusively of triactines ( Figure 4 A).

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

Min Mean SD Max Min Mean SD Max Triactine

BMNH 1893.6.9.2 (H) 97.2 124.7 13.5 162.8 10.9 14.6 1.8 18.2 30 NMV F42333 (= BMNH 1925.11.1.1726) 85.0 117.4 15.3 138.5 9.7 13.3 1.5 15.8 30 NMV F42334 (= BMNH 1925.11.1.1728) 72.9 106.1 15.6 145.8 10.9 14.5 2.3 19.4 30 All specimens 72.9 116.1 7.6 162.8 9.7 14.5 1.0 19.4 – Tetractine Basal

BMNH 1893.6.9.2 (H) 97.2 120.3 11.5 140.9 9.7 13.3 1.4 15.8 30 NMV F42333 (= BMNH 1925.11.1.1726) 72.9 110.2 12.9 133.6 9.7 11.7 1.5 14.6 30 NMV F42334 (= BMNH 1925.11.1.1728) 85.0 107.6 9.6 131.2 9.7 12.5 1.7 14.6 30 All specimens 72.9 112.7 5.5 140.9 9.7 12.5 0.6 15.8 –

Apical

BMNH 1893.6.9.2 (H) 24.3 43.2 7.1 60.7 2.4 4.6 0.9 7.3 30 NMV F42333 (= BMNH 1925.11.1.1726) 36.4 48.1 5.9 60.7 3.6 4.7 0.8 7.3 30 NMV F42334 (= BMNH 1925.11.1.1728) 36.4 43.3 7.0 60.7 3.6 4.4 0.6 4.9 16 All specimens 24.3 44.9 2.3 60.7 2.4 4.6 0.1 7.3 – Diactine

BMNH 1893.6.9.2 (H) – – – – – – – – 0 NMV F42333 (= BMNH 1925.11.1.1726) 500.0 663.6 156.0 850.0 70.0 101.8 14.0 120.0 11 NMV F42334 (= BMNH 1925.11.1.1728) 350.0 614.0 144.0 850.0 50.0 96.7 27.4 140.0 15 All specimens 350.0 638.8 24.8 850.0 50.0 99.2 2.6 140.0 – Spicules ( Table 2):

(i) Diactines ( Figure 4 B): Variable in size. They are club-shaped, with the sharp tip inside the sponge and the rounded one projected outside;

(ii) Triactines ( Figure 4 C): Regular, with conical actines and sharp tips. Some rare triactines have an elevated centre;

(iii) Tetractines ( Figure 4 C): Similar to the triactines, but with an apical actine, which is shorter and thinner than the basal ones. It presents well developed spines, and has a characteristic ring at their base ( Figure 4 D).

Remarks: Spines on the apical actines have never been observed in Leucascus clavatus . Neither has the ring present at the base of the apical actine. The spines of the apical actine showed no special pattern. The ring and the club-shaped diactines are diagnostic characters of L. clavatus . In fact, up to date L. clavatus is the only species of the genus with diactines (the species Leucascus albus sp. nov. has microdiactines). It is possible, however, that there are other Leucascus species with diactines in their skeletons. Brøndsted (1926) identified specimens from New Zealand as L. clavatus based on the presence of diactines where both tips were sharp. These specimens are clearly not L. clavatus , as the diactines were not club-shaped. Brøndsted’s specimens most likely represent a new species of Leucascus . Unfortunately, in the present work these specimens from New Zealand could not be analysed.

Distribution: Indian and Pacific Oceans: Port Phillip Heads (Dendy 1892), Geraldton District (Row & Hôzawa 1931), and Jurien Bay and Dongara—Australia; Halfmoon Bay, Stewart Island—New Zealand (Brøndsted 1926). Spalding et al. (2007) correponding ecoregions are: Bassian, Houtman, and Snares Islands.

Figures

FIGURE 3. Leucascus clavatus. A, Preserved specimens. NMV F 42334 (left) and WAM Z 40143 (right); B, Diactines protruding from the sponge surface of the specimens NMV F 42334 and WAM Z 40143 (in detail). C – F. NMV F 42334. C, Diactine inserted in the choanosome; D, Cortical membrane; E, Spicules in the wall of a choanocyte tube; F, Apical actine projected into the lumen of a choanocyte tube.

FIGURE 4. Leucascus clavatus. A – C. NMV F 42334. A, Atrial membrane; B, Club-shaped diactine; C, Triactine (left) and tetractine (right); D, Apical actine with spines and ring (arrow; SEM) (NMV F 42333).