Callyspongia (Cladochalina) alcoladoi, Busutil & García-Hernández & Díaz & Pomponi, 2018

Busutil, Linnet, García-Hernández, María R., Díaz, M. Cristina & Pomponi, Shirley A., 2018, Mesophotic sponges of the genus Callyspongia (Demospongiae, Haplosclerida) from Cuba, with the description of two new species, Zootaxa 4466 (1) : -

Callyspongia (Cladochalina) alcoladoi sp. nov.

( Figs. 3a–e , 4a–d )

Material examined. Holotype: ANC 0 2.035, Cuba, Joint Cuba – U.S. Expedition R/V F.G. Walton Smith, site C– 53B, Punta del Fraile (NW Punta Maisí, Eastern tip of Cuba), 20.323166° N 74.232412° W, depth 51.5 m, mesophotic coral reef, 5 June 2017, Collectors: M.C. Díaz & L. Busutil.

Description. External morphology: Delicate, smooth ropey and cylindrical branches (3–8 mm in diameter, 20– 30 cm long), profusely branching and anastomosing, with a few spiny projections (2–4 mm wide, 2–4 cm long) that occasionally arise from the branches. The diameter is variable along the length of the branches, sharply decreasing at the tips, ending always in pointed ends ( Fig. 3a–e ). No distinct base, but specimens fixed to the substrate in two or three points. Oscules (1–2 mm in diameter) round and slightly sunken in relation to the surface ( Fig. 3d–e ), located in rows on one side of the branch, at variable positions (0.2–2 cm apart). Color gray-pinkish externally, tan internally. Tan in alcohol. Very smooth surface, visually and to the touch. Firm but compressible in consistency. No sand or foreign material on the surface. Abundant subdermal round cavities (0.25–0.8 mm) throughout the sponge are visible to the naked eye ( Fig. 3d ).

Spicules: Oxeas ( Fig. 4d ), mostly mucronate, few fusiform, 67.6– 73.3 – 85 x 1.5– 2.3 –3 µm.

Skeleton: Ectosome well–developed primary, secondary and tertiary tangential reticulation ( Fig. 4 a–c ). Primary fibers (30–150 µm in diameter), secondary fibers (15–30 µm) and tertiary fibers (8–16 µm), with primary meshes (80–250 µm), secondary meshes (70–210 µm) and tertiary meshes (30–70 µm). In the choanosome, a longitudinal section of the branch shows primary fibers (30–110 µm in diameter) that run longitudinally along the branches and are connected by secondary fibers (8–25 µm). Primaries occasionally anastomose forming wide, large meshes (60–500 µm), while secondary or smaller, more abundant meshes (40–200 µm) occur within them. Meshes are angular with various shapes ranging from triangular, to square or polygonal. Only primary and secondary fibers are cored, primaries with 1–6 spicules, and secondaries with 1–2 spicules ( Fig. 4c ). The pronounced development of a tertiary reticulation in the ectosome suggests the inclusion of this species in the subgenus Cladochalina Carter, 1885 , despite the smooth surface of this species.

Distribution and ecology. East wall of Bahía de Cochinos (S coast of Cuba) and Punta del Fraile (NW Punta Maisí, Eastern tip of Cuba)( Table 2), mesophotic coral reef, depth range: 51.5–73.4 m. A larger specimen (approx. 1 m long) highly ramified and yellowish in color ( Fig. 3b ) was observed but not collected.

Remarks. Callyspongia (C.) alcoladoi sp. nov. does not represent the typical Cladochalina , which is characterized, by having the primaries forming bundles or fibrofascicles, and usually have species with spinose surface projections (i.e. mention here a couple of common Cladochalina species with spiny projections). However, the highly developed tertiary reticulation in the ectosome (typical among Cladochalina species), and the lack of a peripheral condensation in the reticle typical of the subgenus Callyspongia support the closer similarity of Callyspongia (C.) alcoladoi sp. nov. to this subgenus. The occasional spinose projections observed in Callyspongia (C.) alcoladoi sp. nov. may represent certain similarity to the spinose projections found in Cladochalina species. A comparative molecular study is necessary to validate the phylogenetic value of the current subgenera classification and the evolutionary relationships within the Callyspongia genus.

Callyspongia (C.) pedroi sp. nov., Callyspongia (C.) alcoladoi sp. nov. and Callyspongia (C.) strongylophora Hartman, 1955 have similar characteristics, such as lack of a distinct base, and branches with oscules arranged in rows. However, Callyspongia (C.) strongylophora forms a tangled mass of irregularly anastomosing and dividing branches, with strongylote spicules, while the other two species are branching, rarely anastomosing, and have oxeas as spicules ( Tables 3, 4).

Callyspongia (C.) alcoladoi sp. nov. and Callyspongia (C.) scutica Van Soest, 2017 are close in morphology, due to their smooth surface and pointed ends of the branches, but Callyspongia (C.) scutica branches are often somewhat flattened, with a tendency to have the branches in one plane, while Callyspongia (C.) alcoladoi sp. nov. has cylindrical branches, and branches in multiple planes. Furthermore, the primaries of Callyspongia (C.) alcoladoi sp. nov. in the ectosome are much thicker than those ones of Callyspongia (C.) scutica , and the fusiform oxeas are much larger in Callyspongia (C.) scutica ( Tables 3, 4).

Etymology. Both species are dedicated to Dr. Pedro M. Alcolado, who dedicated his life to the study of marine sponges and made important contributions to the knowledge of Caribbean sponge taxonomy and ecology.

Figures

FIGURE 3. Callyspongia (C.) alcoladoi sp. nov. a) Holotype in live habit b) Other specimen in live habit, but not collected c- d) Holotype on deck e) Very smooth surface and round osculum, slightly sunken.

FIGURE 4. Callyspongia (C.) alcoladoi sp. nov. a) Tangential section of ectosome (4X) b) Longitudinal section shows primary, secondary, and tertiary fibers (4X) c) Fibers discretely cored (20X) d) Mucronate oxea (400X).