Grantia kempfi Borojević & Peixinho, 1976

Pereira, Sara Emilly, Azevedo, Fernanda, Hajdu, Eduardo, Cavalcanti, Fernanda F. & Klautau, Michelle, 2025, Calcareous sponges (Porifera, Calcarea) from São Sebastião, São Paulo: new species and new records in two marine protected areas of Southeastern Brazil Ecoregion, Zootaxa 5688 (1), pp. 1-107 : 41-45

Grantia kempfi Borojević & Peixinho, 1976

( Figs. 20 , 21 ; Table 10)

Synonyms: Grantia kempfi — Borojević & Peixinho 1976: 1019; Muricy et al. 2011: 27; Van Soest 2017: 205; Lopes et al. 2025: 179.

Type locality: off Goiana , Pernambuco State, Brazil .

Material examined: UFRJPOR7009, 9147, Saco da Ponta Grossa , São Sebastião Island, Ilhabela, São Paulo State, Brazil, depth 6 m, coll. F. F. Cavalcanti & V. Padula, 03/XII/2008 . UFRJPOR6935, Sumítica Island , Ilhabela, São Paulo State, Brazil, depth 9 m, coll. F. F. Cavalcanti & V. Padula, 02/XII/2008 . UFRJPOR7030, Serraria Islet , São Sebastião Island, Ilhabela, São Paulo State, Brazil, depth 9 m, coll. F. F. Cavalcanti, 04/XII/2008 . UFRJPOR7034, Saco do Poço , São Sebastião Island, Ilhabela, São Paulo State, Brazil, depth 13 m, coll. F. F. Cavalcanti, V. Padula & L. Kremer, 03/XII/2008 . UFRJPOR7039, 9153, 9156, Parcel da Pedra Lisa , Búzios Island, Ilhabela, São Paulo State, Brazil, depth 7 m, coll. F. F. Cavalcanti, 01/XII/2008 . UFRJPOR7048, 9157, Costa do Aquário , Búzios Island , Ilhabela, São Paulo State, Brazil, depth 12 m, coll. F. F. Cavalcanti, V. Padula & R. Berlinck, 05/XII/2008 . UFRJPOR7051, Coroa, Búzios Island , Ilhabela, São Paulo State, Brazil, depth 15 m, coll. F. F. Cavalcanti, V. Padula & L. Kremer, 05/XII/2008 . UFRJPOR9149, Saquinho da Sumítica , Búzios Island, Ilhabela, São Paulo State, Brazil, depth 9 m, coll. F. F. Cavalcanti, 01/XII/2008 .

Comparative material examined: Holotype of Grantia kempfi — MNHN. LBIM. C1975-4 (= MNRJ037 ) (specimen and slides), Off Goiana , Pernambuco State, Brazil (-7.66722, -34.71722), depth 19–20 m, coll. M. Kempf, 04/III/1969.

Colour: White or pinkish beige in life and beige in ethanol ( Fig. 20A ).

Morphology and anatomy: Grantia with an oval body, the basal region wider than the apical one ( Fig. 20A ). The surface is quite hispid due to the projection of numerous diactines and trichoxeas. The single osculum is apical, ornamented with a dense and long crown of trichoxeas. The atrium is also hispid due to the projection of the apical actines of the atrial tetractines. Aquiferous system syconoid, with elongated and unbranched choanocyte chambers ( Fig. 20B ).

The well-developed crown of trichoxeas is supported by T-shaped triactines, with the unpaired actine much thinner than the paired ones. The cortical skeleton consists of several layers of triactines, many of which project their unpaired actine outwards ( Fig. 20C ). When these triactines are bordering the ostia, the unpaired actine is bent over the inhalant aperture ( Fig. 20C , inset). Transitional forms between these cortical triactines and the tubar ones are observed. Additionally, there are giant diactines, with the distal portion protruding through the cortex, inclined obliquely towards the osculum and penetrating only superficially into the choanosome ( Fig. 20B, C ). Trichoxeas can also be found in this layer, tangentially or perpendicularly positioned. The tubar skeleton is articulate, composed of several rows of tetractines and triactines, the latter being more abundant ( Fig. 20D ). The subatrial skeleton is supported by triactines and very rare tetractines ( Fig. 20E ). The atrial skeleton is also thick, formed mainly by tetractines, in addition to few triactines, pointing their unpaired actine to the base of the sponge ( Fig. 20F ).

Spicules ( Table 10):

Trichoxeas: Very long, slender and cylindrical, with sharp tips ( Fig. 21A ).

Large diactines: Curved, thicker at mid-length, with the distal tip lanceolate, while the proximal tip is sharp ( Fig. 21B, C ). Size: 1,400.0 (±774.0)/25.0 (±0.0) µm.

Small diactines: Curved, smooth, fusiform, with both tips sharp ( Fig. 21D ). Size: 129.3 (±41.8)/3.5 (±0.4) µm.

Cortical triactines: Sagittal. Actines are conical, with sharp tips. The unpaired actine can be straight or sharply bent (over the ostia) and is shorter than the paired ones, which are almost straight ( Fig. 21E ). Size: paired—85.1 (±13.1)/8.2 (±1.1) µm; unpaired—67.2 (±10.5)/8.8 (±1.4) µm.

Tubar triactines and tetractines: Sagittal, variable in shape. Basal actines are slightly conical, with sharp to blunt tips. The unpaired actine is straight and longer than the paired ones, which are slightly curved and, sometimes, undulated and unequal in length. The apical actine of the tetractines is short, conical, slightly curved and sharp ( Fig. 21F, G ). Triactines size: paired—70.1 (±12.9)/7.0 (±1.2) µm; unpaired—111.8 (±13.4)/7.1 (±1.3) µm. Tetractines size: paired—78.2 (±11.4)/7.3 (±1.3) µm; unpaired—120.8 (±19.8)/7.6 (±1.1) µm; apical—27.0 (±6.6)/5.1 (±0.9) µm.

Subatrial triactines and tetractines: Strongly sagittal and thinner than the tubar ones. Basal actines are cylindrical, with sharp tips. The unpaired actine is straight and much longer than the paired ones, which are inwardly curved. They are thinner than the tubar ones. The apical actine of the tetractines is short, conical, sharp and slightly curved ( Fig. 21H, I ). Triactines size: paired—65.7 (±19.1)/5.7 (±1.6) µm; unpaired—129.1 (±25.4)/5.9 (±1.1) µm. Tetractines size: paired—83.3 (±13.8)/5.8 (±1.4) µm; unpaired—121.7 (±12.8)/6.7 (±0.7) µm; apical—15.0 (±3.5)/4.4 (±0.9) µm.

Atrial triactines and tetractines: Sagittal. Basal actines vary from cylindrical to conical, with blunt tips. The unpaired actine is straight, tapering abruptly near the base, but may sometimes be swollen near the distal end. It is longer than the paired actines, which are nearly straight and often unequal in length. The apical actine of the tetractines is slightly conical, smooth, curved near the tip and sharply pointed ( Fig. 21J, K ). Triactines size: paired— 80.5 (±16.7)/7.0 (±0.9) µm; unpaired—181.5 (±39.8)/7.6 (±1.0) µm. Tetractines size: paired—90.4 (±18.1)/5.5 (±2.0) µm; unpaired—179.5 (±36.0)/7.1 (±1.1) µm; apical—79.7 (±15.0)/5.8 (±0.9) µm.

Ecology: This species is found in cryptic habitats (caves/holes) or exposed to sunlight on rocky substrate, usually associated with algae turfs. Some of the analysed specimens were partially covered with sediment.

Geographic distribution: Guianan ecoregion— Guyana ( Van Soest 2017). Amazonia ecoregion—Amapá State ( Borojević & Peixinho 1976), Brazil. Northeastern Brazil ecoregion— Rio Grande do Norte, Pernambuco and Alagoas states ( Borojević & Peixinho 1976), Brazil. Eastern Brazil ecoregion— Bahia State ( Borojević & Peixinho 1976) and Espírito Santo State ( Lopes et al. 2025), Brazil. Southeastern Brazil ecoregion—São Sebastião, Búzios and Sumítica Islands (Ilhabela), São Paulo State (present study), Brazil.

Remarks: The specimens correspond well to the original description of Grantia kempfi and subsequent descriptions by Van Soest (2017) and Lopes et al. (2025). Regarding the ostiolar triactines mentioned by Borojević & Peixinho (1976), we interpret these spicules in this study as a variety of cortical triactines since, apart from the bent unpaired actine, they are similar in shape and dimensions.

We found the small fusiform diactines described by Lopes et al. (2025) in the spicule preparations of only two of our specimens, UFRJPOR7009 and UFRJPOR6935. This feature likely represents intraspecific variation, as specimen UFRJPOR7009 clustered phylogenetically with two other specimens that lacked these diactines, showing minimal genetic divergence (p-distance: 0–0.3%). Additionally, the fusiform diactines in our specimens are significantly smaller [129.3 (±41.8)/3.5 (±0.4) µm] compared to those of a specimen from Espírito Santo State [413.5 (±238.2)/14.2 (±2.8) µm]. These observations suggest that the abundance (rare or absent) and size of fusiform diactines in G. kempfi may vary considerably.

Figures

FIGURE 20. Grantia kempfi (UFRJPOR7009). A. Preserved specimen. B. Cross section of the body wall. C. Cross section showing the cortical skeleton (ostiolar triactines in the inset). D. Cross section showing the tubar skeleton. E. Subatrial triactines (arrows) and apical actines of the atrial tetractines. F. Tangential section of the atrial skeleton. cx = cortex, at = atrium.

FIGURE 21. Grantia kempfi (UFRJPOR7009). A. Trichoxea. B. Large diactines. C. Lanceolate tip of a large diactine. D. Small diactine. E. Cortical triactines. F. Tubar triactines. G. Tubar tetractine. H. Subatrial triactines (one of the paired actines is broken). I. Subatrial tetractine. J. Atrial triactine. K. Atrial tetractine.