Craniella crustocorticata Van, 2017, sp. nov.

Craniella crustocorticata sp. nov.

Figures 67 a–f, 68a–f

Material examined. Holotype RMNH Por. 6296, Guyana, ‘Luymes’ Guyana Shelf Expedition, station 80, 7.9333°N 57.2°W, depth 618 m, Van Veen grab, muddy bottom, 1 September 1970.

Paratypes RMNH Por. 9326, Guyana, ‘Luymes’ Guyana Shelf Expedition, station 48, 7.75°N 57.0167°W, depth 500 m, muddy bottom, 30 August 1970 (3 specimens); RMNH Por. 9353, Guyana, ‘Luymes’ Guyana Shelf Expedition, station 80, 7.9333°N 57.2°W, depth 618 m, Agassiz trawl, muddy bottom, 1 September 1970 (2 specimens); RMNH Por. 9354, Guyana, ‘Luymes’ Guyana Shelf Expedition, station 100, 8.0°N 57.4333°W, depth 500 m, Agassiz trawl, muddy bottom, 4 September 1970 (1 specimen).

Description. (Figs 67 a–c) Globular sponges of 3 cm in diameter (holotype) with the surface provided with evenly spread flat-topped conical elevations, 1–2 mm in height and width, an apical flush oscule (shrunk in the holotype). Conical elevations provided with bundles of protruding megascleres (oxeas and triaenes). Color in alcohol broken white, pinkish, or beige brown. Consistency compressible, bladder-like.

Skeleton. (Figs 67 c–f) At the surface there is a thin densely spiculose multilayered crust of tangential cortical oxeas (Figs 67 d–e) overlying extensive subdermal lacunae. The surface crust is carried by strong pillars of choanosomal bundles (Fig. 67 c,f) consisting long oxeas and triaenes, which convene spirally at the center of the sponge body.

Spicules. (Figs 68 a–f) Oxeas, protriaenes, anatriaenes, sigmaspires.

Oxeas (Figs 68 a–b) in two distinct categories, (1) thinner sharply pointed (Figs 68 a,a1), slightly anisoactine, in a large size range, possibly further divisible in longer and shorter, 480– 2345 –6000 x 4.5– 29.8 –54 µm, and (2) strongly fusiform, fat oxeas (Figs 68 b,b1) of the surface skeleton, also in a large size range, possibly divisible in larger and shorter, 324– 596 – 1092 x 24 – 41.9 –86 µm.

Protriaenes including prodiaene modifications (Figs 68 c–d) in two distinct shapes, (1) with thicker, straight rhabdomes (Figs 68 c,c1) and narrow cladomes, often with straight unequal length cladi (Fig. 68 c1), rhabdomes 2750– 3657 –4200 x 6 – 16.3 –24 µm, cladomes 40– 71.5 –180 µm, (longest-)cladi 202– 267 –348 x 10 – 11.2 –14 µm, and (2) with wispy thin rhabdomes (Figs 68 d,d1) and flaring cladomes (Fig. 68 d1) with thin cladi, rhabdomes 1080– 2100 –3990 x 2 – 4.8 –6 µm, cladomes 60– 144 –200 µm, cladi 66– 244 –360 x 1 – 1.8 –3 µm.

Anatriaenes (Figs 68 e,e1) variable in length and thickness but no diversity in cladome shape (Fig. 68 e1), rhabdomes 1200– 3640 –6000 x 3 – 16.7 –24 µm, cladomes 29– 124 –181 µm, cladi 24– 136 –216 x 5 – 15.3 –21 µm.

Sigmaspires (Figs 68 f), small, predominantly C-shaped, 11– 12.8 –15 µm.

Distribution and ecology. Guyana Shelf, slope, depth 500– 618 m.

Etymology. The name is a composite of crusta (L.) = crust and corticatus (L.) = provided with a cortex, referring to the crust-like cortex of tangential cortical oxeas at the surface.

Remarks. The new species is characterized by a bladder-like consistency and a largely tangential surface skeleton. The former condition is suggested to be possibly related to a seasonal massive reproduction phase (P. Cárdenas, pers. comm.). The latter condition is unlike that of the type species of the genus, and other Craniella species. One could argue that it places the present species outside the genus, but e.g. Craniella azorica (Topsent, 1913) (as Craniellopsis) has its cortical oxeas arranged ‘paratangentially’ (see description and illustration in Cárdenas & Rapp 2015), thus forming a bridge between the new species and the type species Craniella tethyoides Schmidt, 1870. This was re-described by Sollas, 1888 (p. 55) and Van Soest & Rützler (2002) (their p. 92, fig. 6), but remains not well known. Because the sigmaspires are measured as 35 x 6 µm and the cortical oxeas are ‘radially’ arranged, it is unlikely to be conspecific with the new species.

Craniella carteri Sollas, 1886 from NE Brazil has similar shape as the new species, but differs in cortical structure (radial arrangement of cortical oxeas) and the lack of sigmaspires.

Craniella schmidtii Sollas, 1888 from deep water off Culebra, W of Puerto Rico, is described as similar to Craniella cranium, with choanosomal oxeas only up to 1600 x 40 µm and cortical oxeas only up to 414 x 27 µm. Also the triaenes have considerably shorter rhabdomes, while the sigmaspires are given as 19.7 µm. These spicule measurements are sufficiently different to conclude that C. schmidtii is not conspecific with the present specimens.

Two further Caribbean species Craniella insidiosa Schmidt, 1870 and Craniella lens Schmidt, 1870, both from Florida, were not properly described, nor re-described, and thus remain unrecognizable. In a preparation of the type of C. lens, Sollas (1888) (p. 54) could not find any sigmaspires. Also the anatriaenes of this species had rhabdomes up to 45 µm in diameter, twice as thick as in the present new species.

Craniella quirimure Peixinho, Cosme & Hajdu, 2005 from intertidal and shallow-water mangroves in NE Brazil, has a different habitus (lacking the flat-topped papilla-like structures of the new species), and the cortical oxeas are arranged perpendicular to the surface; most triaenes are distinctly thinner than those of the new species.

Trachygellius corticata Boury-Esnault, 1973 was reassigned to Craniella by Muricy et al. 2011, but this is unlikely in view of the small size and rugose condition of the ‘cortical’ oxeas. These appear similar to spined microxeas in Cinachyrella kuekenthali (Uliczka, 1929). Craniella cortical oxeas are smooth and much larger. Possibly, Boury-Esnault’s suggestion for a separate genus for her specimen has merit. T. corticata differs strongly from the present new species, e.g. by lacking triaenes and proper cortical oxeas.