Craniella curviclada sp. nov.

(Figs. 13–14; Tab. 4)

Diagnosis. Craniella globular, without a root, with a double-layered cortex; three categories of smooth oxeas, two categories of protriaenes (largest category, slightly anisoclad with bent tips of clads, and smallest category, isoclad and very slender) and one category each of anatriaenes and sigmaspires.

Synonyms. Cinachyra sp. n., Muricy et al. 2006: 115.

Material examined. Holotype. MNRJ 20961, REVIZEE Programme sta. Central 2- F20, Espírito Santo State, Southeastern Brazil (19°17’14” S, 37°57’13” W, slope, Espírito Santo Basin, circa 265 km E off Vitória City), dredging, 500 m depth, coll. N.Oc. Astro-Garoupa team, 22 November 1997 .

Description. The single specimen has been sectioned for study and only half is preserved. Globular sponge without a root (Figs. 13A–D); 17 mm in diameter. In cross section, dense concentration of spicules at the center of the body and near the surface (Fig. 13A). Surface, even, but rough and slightly hispid. Oscules or pores not visible. Color, in vivo not recorded, and light beige in ethanol. Consistency, firm, but compressible.

Skeleton. Radial, with main bundles of oxeas I from the center to the surface, protruding up to 350 µm above the surface (Fig. 13E), up to 250 µm wide and up to 500 µm of distance to each other (Fig. 13F). Oxeas II only in the center of body, as a disorganized mass (Fig. 13F). Cortex with two layers; outer layer with 930 µm thick and sub-dermal cavities up to 500 µm in diameter, and inner layer with an irregular palisade of cortical oxeas III up to 700 µm high (Figs. 13E, G). Protriaenes and anatriaenes in the main spicule bundles; cladomes of protriaenes usually pierce the surface together with the oxeas I (Fig. 13H). Sigmaspires scattered in the ectosome and choanosome, and around canals (Figs. 13I –J). Choanosome, dense with few canals; approximately 500 µm in diameter.

Spicules. Megascleres (Tab. 4):

Oxeas I (Fig. 14A–B) abundant, anisoactinal (anisoxeas), fusiform, straight to curved, smooth. Extremities, very distinct (one with a typically hastate tip and the opposite end filiform): 1600–3841–5000/28–38–53 µm.

Oxeas II (Fig. 14C–D), less abundant than the oxeas I, slightly fusiform, isoactinal, straight or curved, and smooth. Extremities, equal, with hastate to acerate tips: 915–1200–1450/18–26–30 µm.

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Oxeas III (Fig. 14E–F), abundant, exclusively cortical (size widely variable), stout, smooth, fusiform and often slightly curved. Extremities equal, with tips acerate: 450–658–900/29–36–49 µm.

Protriaenes I (Figs. 14G–H), abundant. Rhabdome, thicker near the cladome, thin after 950 µm in opposite direction to the cladoma, then becoming slightly thicker again and very slender and flexuous up to the opposite extremity: 1360– 1193–2725 /14–20–24 µm. Clads, straight to slightly sinuous, with curved extremities and making an angle of 150º–160º with the rhabdome: 122–165–223/ 12–17–22 µm.

Protriaenes II (Fig. 14I –K), less common than the protriaenes I. Rhabdome, straight and becoming thin near the cladome: 301–556–1075/ 7–10–14 µm. Cladome, small, with straight and pointed clads, making an angle of about 135º with the rhabdome: 19–55–115/ 5–7–10 µm.

Anatriaenes (Fig. 14L–M), less common than the protriaenes I and II, exclusively choanosomal. Rhabdome, larger than that of both protriaenes, with variable thickness: 2750–3890–6500/22–32–41 µm. Cladome, with clads making an angle of approximately 60º with the rhabdome: 68–135–140/14–22–29 µm.

Microscleres (Tab. 4):

Sigmaspires (Fig. 14N), very abundant, ‘c’ or ‘s’ shaped and entirely microspined (with a few large spines): 14–15–17/0.5–2.0 µm.

Ecology and bathymetric distribution. No macrosymbionts were observed on this sponge. The only specimen was collected from soft seabed with a mix of mud and carbonate sand, at 500 m depth (Lavrado & Ignacio 2006; Muricy et al. 2006).

Distribution. Known only from the type locality, the continental slope off Espírito Santo State, SE Brazil, SW Atlantic (Fig. 1).

Etymology. The name ‘curviclada’ refers to the curved tips of clads of the larger protriaenes (protriaenes I of this study).

Remarks. Unlike Craniella crustocorticata, Craniella curviclada sp. nov. fits well in the diagnosis of Craniella proposed by Carella et al. (2016), due to its globular shape, absence of porocalices, and presence of a distinct two-layered cortex.

Now forty-three species of Craniella are known worldwide; including Craniella curviclada sp. nov., of which 16 occur in the Atlantic Ocean: eight in the western Atlantic, seven in the eastern Atlantic and one occurring in the North, East and West Atlantic (Tab. 4). The new species is set apart from all species of Craniella from the Atlantic due to either features of habit, surface, spiculation or a combination of these. These differences are described below.

Craniella australis Samaai & Gibbons 2005, Craniella azorica, Craniella carteri, Craniella metaclada (Lendenfeld 1907), Craniella monodi (Burton 1929) and Craniella zetlandica (Carter 1872) lack sigmaspires and Craniella disigma Topsent 1904 has two categories of sigmaspires. Since one category of sigmaspires is present in Craniella curviclada sp. nov., six previous species are set apart from the new species (Tab. 4). Remarkably, protriaenes of Craniella australis have clads with slightly bent tips (Saamai & Gibbons, 2005: 10; Fig.7), which are similar to those of Craniella curviclada sp. nov., but these protriaenes are longer and bear smaller clads and cladome than those of the new species (Figs. 14G–H); viz. Craniella australis (rhabd. 819–4000/9–65; ca. 30 µm of distance between clads) and Craniella curviclada sp. nov. rhabd. 1360–2725 /14–24; ca. 200 µm of distance between clads).

Craniella cranium (Müller 1776), Craniella cranium f. microspira Lévi 1967 and Craniella schmidtii Sollas 1886 have two categories of oxeas instead of three as in the new species. Further, Craniella schmidtii has smaller choanosomal oxeas, up to 1600 µm (vs. up to 5000 µm in Craniella curviclada sp. nov.).

Craniella gravida sensu Pollock 1998, Craniella insidiosa Schmidt 1870, Craniella lens Schmidt 1870, Craniella tethyoides Schmidt 1870 and Craniella zetlandica are poorly described and their re-description is beyond the scope of this study. However, Craniella insidiosa has a papillose habit (vs. globular habit in Craniella curviclada sp. nov.) and Craniella tethyoides has anatriaenes bearing smaller clads, 70–90 µm in length (vs. 68 – 140 µm in length in Craniella curviclada sp. nov.).

Craniella crustocorticata has a root at the base, a strongly conulose surface, oxeas with nearly equal extremities, a single-layered cortex, and sigmaspires with relatively many large spines in comparison to Craniella curviclada sp. nov. . The new species differs from Craniella crustocorticata by the absence of a root at the base, absence of conules on the surface, presence of two-layered cortex in the skeleton, stout anisoactinal oxeas, and sigmaspires with fewer spines (viz., see results of this study).