Ernstia rocasensis, Klautau, 2017

Klautau, Michelle, 2017, Taxonomy and phylogeny of calcareous sponges (Porifera: Calcarea: Calcinea) from Brazilian mid-shelf and oceanic islands, Zootaxa 4311 (3), pp. 301-344 : 327-328

Ernstia rocasensis sp. nov.

( Figs 12 A–H; Table 13)

Synonyms. Clathrina sp. nov. 2, Klautau et al. 2013: 449.

Diagnosis. Ernstia with yellow to lemon green cormus formed by irregular and loosely anastomosed tubes. watercollecting tubes are present. Triactines and tetractines occur in approximately the same proportion and they can be distinguished in two categories each: normal and deformed.

Material examined (Five specimens). Holotype: UFRJPOR 6664, Cemitério Tide Pool , Rocas Atoll , Rio Grande do Norte State, 0.5–2 m depth, coll. A. Padua and R. Berlandi, 12 July 2011 . Paratypes: UFRJPOR 6617, Garoupinha Tide Pool, Rocas Atoll , Rio Grande do Norte State, 0.5–1 m depth, coll. A. Padua and R. Berlandi, 0 5 July 2011 . UFRJPOR 6693, Barreta Falsa, Rocas Atoll , Rio Grande do Norte State, 0.5–3 m depth, coll. A. Padua and R. Berlandi, 22 July 2011 . Additional material: MNRJ 2130 , Barreta Falsa, Rocas Atoll , Rio Grande do Norte State, 1 m depth, coll. G. Muricy, 0 3 March 1999 ; MNRJ 2137 , Barreta Falsa, Rocas Atoll , Rio Grande do Norte State, 1 m depth, coll. G. Muricy, 0 3 March 1999 .

Etymology. From the type locality, Rocas Atoll.

Colour. Bright yellow, sometimes lemon green in life, and white or light beige in ethanol.

Morphology. This sponge is friable and thick incrusting, usually spread on the substrate. The cormus is composed of loosely and irregularly anastomosed tubes ( Fig 12 A). Large water-collecting tubes are present and form few apical oscula (2 x 2 mm).

Anatomy. Cells with granules were not present. The skeleton has no special organization and it is composed of triactines and tetractines in approximately the same proportion ( Fig 12 B). There are two categories of triactines and two of tetractines. The first category has a common shape, while the second one resembles deformed spicules. The deformed spicules frequently have actines with different sizes and their tips are strongly rounded, ending abruptly or bending like a handlebar. Sometimes their actines are stout in the middle, and one or more tips are telescopic. These spicules are not very abundant, but they were found in all five analysed specimens, mainly in UFRJPOR 6617. Trichoxeas were found only in one specimen (UFRJPOR 6664).

Spicules ( Figure 12 ; Table 13). Trichoxeas. Very thin, straight and long (figure not shown).

Specimen Spicule Length (µm) Width (µm) n

min mean sd max min mean sd max

UFRJPOR 6664 (H) Triactine I 75.0 90.1 5.8 100.0 5.0 7.4 0.8 10.0 30 Triactine II 37.8 56.6 12.2 81.0 6.8 8.0 0.6 9.5 20 Tetractine I 85.0 92.1 4.8 105.0 6.3 7.5 0.2 7.5 30 Apical 45.0 96.6 32.7 155.0 5.0 5.1 0.5 7.5 30 Tetractine II 37.8 53.5 10.7 75.6 6.8 8.0 0.3 8.1 20

UFRJPOR 6617 (P) Triactine I 80.0 90.8 6.1 102.5 5.0 7.3 1.2 12.5 30 Triactine II 24.3 46.8 13.1 64.8 6.8 7.6 0.7 8.1 20 Tetractine I 77.5 88.7 6.7 107.5 6.3 7.3 0.5 7.5 30 Apical 52.5 79.8 23.7 142.5 5.0 5.0 0.2 6.3 30 Tetractine II 32.4 53.1 11.7 72.9 5.4 7.1 1.1 8.1 20

UFRJPOR 6693 (P) Triactine I 75.0 89.4 6.7 105.0 5.0 6.9 0.9 7.5 30 Triactine II 35.0 48.4 8.8 65.0 7.5 8.4 0.9 10.0 20 Tetractine I 72.5 87.8 6.2 100.0 5.0 7.0 0.8 7.5 30 Apical 30.0 58.8 13.5 87.5 3.8 5.0 0.2 5.0 30 Tetractine II 20.0 47.5 12.1 70.0 7.5 9.3 0.9 10.0 15 Triactines I: Equiangular and equiradiate. Actines are slightly conical and slightly undulated near the tip, which is blunt ( Fig 12 C).

Triactines II (deformed): Equiangular and equiradiate or with one, two, or three actines with different lenghts. Actines are cylindrical with rounded tips that end abruptly or bend like a handlebar. Sometimes one of the actines is thicker in the middle. There are also actines that seem to have been incompletely synthesised and their tips end telescopically ( Fig 12 D).

Tetractines I: Equiangular and equiradiate but sagittal spicules are also present. Actines are slightly conical and slightly undulated near the tip, which is blunt ( Fig 12 E). The apical actine is shorter and thinner than the basal ones, smooth, sharp and needle-like or conical ( Figs 12 F, G).

Tetractines II (deformed): Same description of the deformed triactines ( Fig 12 H). The apical actine is similar to that of the common tetractines.

Ecology. Specimens of this species were found from 0.5 to 3 m of depth, in shaded sites only partially exposed to sunlight, usually on vertical walls and inside small crevices. Algae were found associated with Ernstia rocasensis sp. nov.

Distribution. Rocas Atoll, off NE Brazil.

Remarks. Ernstia rocasensis sp. nov. is the only species of Ernstia with a category of deformed spicules. As these spicules were present in the five analysed specimens, we are considering them as diagnostic characters. These spicules are enough to differentiate the new species from all the other species of Ernstia .

Figures

FIGURE 12. Ernstia rocasensis sp. nov. A—Holotype after fixation. B—Section. C—Triactine. D—Triactine (deformed). E—Tetractine. F, G—Tetractines (ap: apical actine). H—Tetractine (deformed).