Ernstia citrea, 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 : 323-325

Ernstia citrea sp. nov.

( Figs 10 A–G; Table 11)

Synonyms. Clathrina sp., Moraes et al. 2003: 17. Clathrina sp. n. 1, Moraes et al. 2006: 166. Clathrina sp. nov. 1, Klautau et al. 2013: 449. Ernstia sp., Padua & Klautau 2016: 554.

Diagnosis. Ernstia with a spherical yellow cormus formed by regular and tightly anastomosed tubes and large and high (2 mm) apical osculum. Skeleton composed of triactines and tetractines.

Material examined ( Six specimens). Holotype: UFRJPOR 6621, Garoupinha Tide Pool, Rocas Atoll, Rio Grande do Norte State, Brazil, 0.5–1.0 m depth, coll. A. Padua & R. Berlandi, 0 5 July 2011 . Paratypes: UFRJPOR 6649, UFRJPOR 6651, Cemitério Tide Pool , Rocas Atoll, Rio Grande do Norte State, Brazil, 0.5–2.0 m depth, coll. A. Padua & R. Berlandi, 12 July 2011 . Additional material: MNRJ 2130 , MNRJ 2198 , Barreta Falsa , Rocas Atoll, Rio Grande do Norte State, Brazil, 3 m depth, coll. G. Muricy, 0 3 March 1999 ; MNRJ 2925 , Barretinha , Rocas Atoll, Rio Grande do Norte State, Brazil, 2 m depth, coll. E. Villanova, 19 November 1999 .

Etymology. From the Latin citrea (=yellow), for the yellow colour of the cormus.

Colour. Bright yellow to greenish-yellow in life and white or light beige in ethanol.

Morphology. The cormus is massive and spherical, soft and not very compressible. It is formed by thin (3 mm in diameter), regular and tightly anastomosed tubes ( Fig 10 A). water-collecting tubes are present and converge frequently to one or two conspicuous apical oscula (1–2 mm high). After fixation, the oscula collapse.

Anatomy. No cells with granules were observed. The skeleton has no special organization and it is composed of triactines and tetractines ( Fig 10 B). Triactines occur in almost the same proportion as tetractines.

Spicules ( Figure 10 ; Table 11). Triactines: Equiangular and equiradiate. Actines are conical to slightly conical and slightly undulated, with blunt tips ( Figs 10 C, D).

Specimen Spicule Length (µm) Width (µm) N

min Mean sd max min mean sd max

UFRJPOR 6621 (H) Triactine 72.9 81.3 4.3 89.1 9.5 10.4 0.7 12.2 30 Tetractine 70.2 82.4 6.2 99.9 8.1 10.4 1.1 13.5 30 Apical 29.7 56.7 12.7 83.7 4.1 4.6 0.7 5.4 30 UFRJPOR 6649 (P) Triactine 67.5 76.9 4.2 86.4 8.1 10.1 0.8 10.8 30 Tetractine 70.2 80.3 5.3 91.8 8.1 9.9 0.8 10.8 30 Apical 29.7 48.2 8.1 64.8 4.1 5.2 0.5 5.4 30 UFRJPOR 6651 (P) Triactine 70.2 83.1 6.4 99.9 8.1 10.2 0.8 12.2 30 Tetractine 70.2 80.6 5.1 91.8 8.1 10.4 0.8 12.2 30 Apical 32.4 56.4 17.7 108.0 2.7 5.0 0.7 5.4 30 Tetractines: Equiangular and equiradiate. Actines are conical, slightly undulated, with blunt tips ( Figs 10 E, F). The apical actine is thinner than the basal ones. It is smooth, straight or slightly curved at the end and sharp ( Fig 10 G).

Ecology. Ernstia citrea sp. nov. is a common species in Rocas Atoll. It was found from 0.5 to 3 m of depth, always in shaded areas, only partially exposed to sunlight. It occurs usually on vertical walls and on the ceilings of small crevices. No macroscopic organisms were found associated with this species.

Distribution. Rocas Atoll, off NE Brazil.

Remarks. Ten species of Ernstia are currently recognized: E. chrysops Van Soest & De Voogd, 2015 , E. indonesiae Van Soest & De Voogd, 2015 , E. klautauae Van Soest & De Voogd, 2015 , E. laxa ( Kirk, 1896) , E. naturalis Van Soest & De Voogd, 2015 , E. quadriradiata ( Klautau & Borojevic, 2001) , E. sagamiana ( Hôzawa, 1929) , E. septentrionalis ( Rapp et al., 2001) , E. sueziana (transferred to Ernstia in the present paper, see above), and E. tetractina ( Klautau & Borojevic, 2001) . Ernstia citrea sp. nov. is so far the only species of this genus with spherical, yellow cormus, with a conspicuous long osculum.

Figures

FIGURE 10. Ernstia citrea sp. nov. A—Holotype after fixation. B—Section. C, D—Triactines. E, F—Tetractines. G— Tetractine (ap: apical actine).