Grantia kempfi Borojević & Peixinho, 1976

Grantia kempfi Borojević & Peixinho, 1976 View in CoL

( Figs 14 View FIGURE 14 , 15 View FIGURE 15 ; Table 10 View TABLE 10 )

Synonyms: Grantia kempfi, Borojević & Peixinho 1976: 1019 , Muricy et al. 2011: 27, Van Soest 2017: 205.

Material examined: UFRJPOR 8831 , Escalvada Island , 18 m depth, 31.iii.2017, colls. A. Padua and C. Leal. UFRJPOR 8803 , Marine Artificial Reef Vitória 8B , 22 m depth, 30.iii.2017, colls. A. Padua and C. Leal .

Diagnosis: Grantia with syconoid aquiferous system. The cortical skeleton is composed of two categories of diactines, one small and fusiform (rare) and the other large and lanceolated, and triactines. Tubar skeleton composed of triactines and tetractines, the latter being less abundant. Subatrial skeleton composed of triactines and tetractines (very rare). Atrial skeleton composed of few triactines and tetractines.

Description: Vase shaped sponge. Osculum single and apical, with a neck and a crown of trichoxeas ( Fig 14A View FIGURE 14 ). Colour white alive and white to beige after fixation ( Fig 14A View FIGURE 14 ). Consistency friable and fragile. External surface hispid with long diactines protruding through the cortex. Atrium central and hispid due to the apical actines of the atrial tetractines ( Figs 14B, E View FIGURE 14 ). Radial tubes are fully coalescent, long and arranged side by side ( Fig 14B View FIGURE 14 ). Aquiferous system syconoid.

The oscular crown comprises long and smooth trichoxeas and diactines II ( Figs 15A, C View FIGURE 15 ). The oscular neck has a skeleton formed by T-shaped triactines ( Fig 15D View FIGURE 15 ). Cortical skeleton composed of scattered rare small diactines (diactines I), longitudinal large diactines (diactines II) and tangential triactines ( Fig 14C View FIGURE 14 ). The lanceolated tip of the diactines II protrudes through the cortex, while the fusiform tip penetrates the body. Tubar skeleton articulated, composed of rows of triactines and tetractines, the latter being less abundant ( Figs 14B, D View FIGURE 14 ). Subatrial skeleton composed of triactines and very rare tetractines with the unpaired actine pointing to the cortex ( Fig 14E View FIGURE 14 ). Atrial skeleton composed of triactines and abundant tetractines, with a long apical actine projected into the atrial cavity ( Figs 14E, F View FIGURE 14 ).

Spicules ( Figs 15B–J View FIGURE 15 ; Table 10 View TABLE 10 ).

Cortical diactines I: Fusiform with sharp tips ( Fig 15B View FIGURE 15 ). Very rare. Size: 413.5 (± 238.2)/ 14.2 (± 2.8) µm (N = 4).

Cortical diactines II: Fusiform, undulated and slightly curved, one tip sharp and the other lanceolated ( Fig 15C View FIGURE 15 ). Mostly broken due to the huge size. Size: 945/ 4.5 µm (N = 1).

Cortical triactines: Sagittal. Actines conical, straight, with sharp tips. Paired actines slightly undulated and longer than the unpaired one ( Fig 15E View FIGURE 15 ). Unpaired actine straight or bent when surrounding a canal. Size: paired actine—131.6 (± 31.4)/ 11.6 (± 1.5) µm (N = 20); unpaired actine—74.2 (± 23.4)/ 12.4 (± 1.8) µm (N = 20).

Tubar triactines and tetractines: Sagittal. Actines conical, straight, with sharp tips. Paired actines may have different sizes and the shorter one can be curved. Nonetheless, they are always smaller than the unpaired actine ( Figs 15 F, G View FIGURE 15 ). The apical actine of the tetractines is curved, conical, smooth and small, with sharp tips ( Fig 14E View FIGURE 14 ). Size (triactines): paired actine—92.3 (± 12.5)/ 8.1 (± 0.9) µm (N = 20); unpaired actine—121.2 (± 17.6)/ 8.9 (± 1.2) µm (N = 20). Size (tetractines): paired actine—96.1 (± 16.0)/ 7.8 (± 0.8) µm (N = 20); unpaired actine—128.2 (± 20.4)/ 9.2 (± 1.3) µm (N = 20); apical actine—38.5 (± 5.7)/ 7.6 (± 0.9) µm (N = 20).

Subatrial triactines and tetractines: Sagittal. Paired actines slightly conical, with sharp to blunt tips and curved or straight. The unpaired actine is slightly conical to conical, straight, with sharp tips. It is longer than the paired ones ( Fig 15H View FIGURE 15 ). Apical actine of tetractines curved, conical, smooth and small, with sharp tips. Subatrial tetractines are very rare, only three were observed on the skeleton sections, therefore they were not measured. Size: paired actine—87.1 (± 32.3)/ 6.9 (± 1.3) µm (N = 16); unpaired actine—167.2 (± 31.6)/ 8.6 (± 1.1) µm (N = 16).

Atrial triactines and tetractines: Sagittal. Actines slightly conical to conical with sharp tips ( Fig 15I View FIGURE 15 ). The unpaired actines have variable sizes, usually smaller or the same size of the paired ones. Nonetheless, some longer unpaired actines were also observed ( Figs 15I, J View FIGURE 15 ). Apical actine of tetractines curved, slightly conical to conical, smooth and large, with sharp tips ( Fig 14E View FIGURE 14 ). Size (triactines): paired actine—166.7 (± 25.2)/ 9.2 (± 1.6) µm (N = 12); unpaired actine—188.8 (± 46.0)/ 9.8 (± 2.0) µm (N = 12). Size (tetractines): paired actine—148.0 (± 46.0)/ 9.8 (± 2.0) µm (N = 20); unpaired—180.8 (± 39.3)/ 9.6 (± 1.7) µm (N = 20); apical actine—128.3 (± 22.4)/ 8.5 (± 1.5) µm (N = 20).

Ecology: Specimens from Espírito Santo were attached to other organisms (UFRJPOR 8831 on algae and UFRJPOR 8803 on Carijoa sp. ) in depths of 18 and 22 m. Previously described material was collected on sandy bottoms, from 18 to 71 m depth ( Borojević & Peixinho 1976; Van Soest 2017).

Distribution: Guianan ecoregion— Guyana Shelf ( Van Soest 2017). Amazonia ecoregion—Amapá State ( Borojević & Peixinho 1976). Northeastern Brazil ecoregion— Rio Grande do Norte State; Pernambuco State (type locality); Alagoas State ( Borojević & Peixinho 1976). Eastern Brazil ecoregion— Bahia State ( Borojević & Peixinho 1976); Guarapari, Espírito Santo State (present study).

Taxonomic remarks: Initially described to the Brazilian coast, Grantia kempfi was later found in the Guyana Shelf ( Van Soest 2017). Originally, the subatrial skeleton of G. kempfi was described as having only triactines and only the large lanceolated diactine was mentioned ( Borojević & Peixinho 1976). Reanalysing the slides of the holotype (MNHN.LBIM.C 1975-4 = MNRJ 037), we found three subatrial tetractines and a smaller fusiform diactine. Likewise, in our material the fusiform diactines and the subatrial tetractines were also very rare. These spicules were not described for the Guyana Shelf material; however, we believe that they could have easily been overlooked due to their rarity.

Two differences must be considered comparing ours to the type material: (1) the choanocyte chambers of G. kempfi were described as ramified distally. Nonetheless, the original slides of the holotype were not sectioned properly in a transversal orientation; therefore, we were not able to confirm this feature. In our specimen, the choanocyte chambers do not ramify and run side by side radially to the atrium. (2) Regarding the sizes of the spicules, the specimens from Espírito Santo have larger atrial triactines and tetractines when compared to the holotype ( Table 10 View TABLE 10 ). Nonetheless, the shape is identical. For those reasons, we identify our material as Grantia kempfi .