Acanthella saladinorum, Sim-Smith & Hickman & Kelly, 2021

Sim-Smith, Carina, Hickman, Cleveland & Kelly, Michelle, 2021, New shallow-water sponges (Porifera) from the Galápagos Islands, Zootaxa 5012 (1), pp. 1-71 : 34-36

Acanthella saladinorum sp. nov.

( Fig. 15 )

Material examined. Holotype — MCCDRS9418, Las Cuevas , Floreana Island, 1.262° S, 90.358° W, 18 m, 7 Feb 2004.

Type locality. Las Cuevas , Floreana Island ; 18 m.

Habitat and distribution. Only known from type locality. Found on rock substrate.

Description. Thinly encrusting base, 1 mm thick, from which arises a thick dome of convoluted, branching lamellae, 10–20 mm high, anastomosing in sections to render the surface honey-combed in some areas ( Fig. 15A ); lamellae are well separated in other areas. The surface of the sponge is covered in a translucent white, glistening membrane that has a velum-like texture ( Fig. 15C ) and is easily detached from the rest of the sponge. No oscules were visible. Texture is soft, compressible and easily torn. Colour in life is dull orange, colour in ethanol is tan.

Skeleton. Choanosomal skeleton contains ascending dendritic tracts of styles that are interwoven with sinuous strongyles. Styles echinate from the primary tracts and are perpendicular to the surface of the sponge, sometimes protruding beyond the surface. Spongin is abundant within or surrounding the primary tracts. No special ectosomal skeleton ( Fig. 15B ).

Spicules. Megascleres— Styles ( Fig. 15D ) with strongly attenuating distal ends in a large size range; 749 (453– 1069) × 25 (17–32) µm (n = 28). Strongyles ( Fig. 15E ), thin and sinuous; 526 (245–872) × 11 (7–16) µm (n = 20).

Etymology. Named for Kenneth and Diane Saladin, who led student study groups to the Galápagos Islands starting in 2002, and who provided major funding for Galápagos conservation, research, and infrastructure projects over many years. Kenneth Saladin was Distinguished Professor of Biology, Emeritus, at Georgia College and regularly taught a class on Natural and Cultural History of the Galápagos Islands.

Remarks. Only one species of Acanthella has been described from the eastern Pacific; A. danerii Costa, Bavestrello, Pansini & Bertolino, 2020 from the Chilean fjords. That species can be differentiated from A. saladinorum sp. nov. by the possession of sinuous oxeas in addition to styles and strongyles.

An unnamed species of Acanthella was described from the Colombian Pacific ( Lizarazo Rodríguez et al. 2020), but that species differs from A. saladinorum sp. nov. in that it is bright orange in colour, dendritic in morphology, and has shorter and much thinner styles (590 (348–813) × 9 (4–15) µm).

Order Tetractinellida Marshall

Figures

FIGURE 15. Acanthella saladinorum sp. nov., holotype MCCDRS9418: A. Holotype, in situ. B. Vertical cross section of the choanosome showing the dendritic, partially spongin-encased ascending tracts of styles and sinuous strongyles (red arrows) and the echinating styles that form conules at the surface (black arrows). C. Holotype, preserved. D. Styles, with strongly attenuating distal ends. E. Sinuous strongyles.