Amphimedon palmata Calcinai & Belfiore, 2020

Calcinai, Barbara, Belfiore, Giuseppe, Pica, Daniela, Torsani, Fabrizio, Palma, Marco & Cerrano, Carlo, 2020, Porifera from Ponta do Ouro (Mozambique), European Journal of Taxonomy 698, pp. 1-56 : 17-19

Amphimedon palmata Calcinai & Belfiore sp. nov.

urn:lsid:zoobank.org:act:3A60B0A0-7705-4C64-96FE-83FF25D1045A

Fig. 10

Diagnosis

This species of Amphimedon is characterized by flattened and rounded branches, and oscules located on the branches’ rims.

Etymology

Named after the sponge growth form, consisting of flat and rounded branches.

Material examined

Holotype

PONTA DO OURO • a branched portion, alcohol preserved, 5cm high; 26°49′50.408″ S, 32°53′45.974″ E; Doodle; 18 m deep; 14 Nov. 2015; Cerrano leg.; MSNG 61504 .

Description

Live sponge arborescent-palmate ( Fig. 10A ), with oscula scattered on the upper margin of the flattened branches ( Fig. 10A ). The color is pinkish in life; ochre for the fragment preserved in alcohol. The surface is uneven, but optically smooth; the consistence is soft and compressible. The examined sample is a short palmate fragment 0.5–1 cm in thickness.

SKELETON. Ectosome ( Fig. 10B ) with multispicular primary fibers (40–60 μm in diameter) that form rounded and irregular meshes, 180–250 μm wide, with paucispicular secondary fibers (15 μm in average diameter). In the best-preserved parts, the sponge is covered by a thin dermal membrane with scattered tangential oxeas ( Fig. 10C ). Choanosomal primary fibres protrude and are pierced by scattered spicules; the ascendants, multispicular primary fibers (35–50 μm in diameter), are linked to plurispicular secondary fibers (20–50 μm in diameter). The meshes are irregular or polygonal (100–300 μm) ( Fig. 10D ).

SPICULES. Curved oxeas ( Fig. 10E ), 90–(103.5, 6.5)–112 μm in length and 2.75–(5.3, 0.9)–6.25 μm wide.

Remarks

This species belongs to the genus Amphimedon that is characterized by an optically smooth surface, and a regular, tangential, ectosomal network with rounded meshes of a single size. Ends of choanosomal, longitudinal, primary fibers are barely protruding. Spongin is abundant ( Desqueyroux-Faúndez & Valentine 2002b).

Out of 57 species of the genus Amphimedon , 30 are recorded in the Indo-Pacific Ocean, 13 of which are from the West Indian Ocean ( Van Soest et al. 2019).

The examined material is close to A. ochracea ( Keller, 1889) in the fiber, mesh and spicule dimensions; Keller (1889), in fact, reported the main fibers with a thickness of 50 μm, and secondary fibers of 10–15 μm. The mesh sizes are between 0.1 and 0.15 mm. Oxeas are straight and pointed, 100 μm long but thinner (1.5 μm in diameter). The main difference is in the shape, color and general morphology of the sponge. Keller’s species is ochraceous and has rounded branches, while the new species is pinkish and has flattened branches; in A. ochracea the large oscules are star-shaped and located along the branches, not on the rims. Amphimedon brevispiculifera ( Dendy, 1905) , as described above, is purple and has a different skeleton structure. The other species of the area, A. chloros Ilan, Gugel & Van Soest, 2004 , A. dinae Helmy & Van Soest, 2005 , A. hamadai Helmy & Van Soest, 2005 , A. hispidula ( Ridley, 1884) , A. jalae Helmy & Van Soest, 2005 , A. navalis Pulitzer-Finali, 1993 , A. rubida Pulitzer-Finali, 1993 , A. rubiginosa Pulitzer-Finali, 1993 and A. spinosa Pulitzer-Finali, 1993 , show a morphology from encrusting to cylindrical, never arborescent or palmate as the specimen here described. Amphimedon delicatula (Dendy, 1889) , recorded from Sri Lanka, has a similar shape (“bushily lamellar”), but presents very stout choanosomal primary fibers, 126 μm in diameter. Amphimedon subcilindrica ( Dendy, 1905) is described as a cylindrical, repent-ramose sponge but with bigger oxeas (140 ×8 μm) and different choanosomal skeleton (stout primary fibers, up to 66 μm, and sub-rectangular meshes). All the other species are different either in spicule size, color or growth form.

Based on the peculiar morphological features of A. palmata sp. nov. and on the morphological differences with all the other species, A. palmata sp. nov. is considered a new species of the genus Amphimedon .

Figures

Fig. 10. Amphimedon palmata Calcinai & Belfiore sp. nov. A. The holotype MSNG 61504 in situ. B. Ectosomal skeleton. C. Ectosomal skeleton covered by a thin dermal membrane with scattered tangential oxeas. D. Choanosomal skeleton. E. Oxea.