Grantia asconoides ( Breitfuss, 1896 )

Morozov, Grigori & Strelkova, Natalia, 2024, On some Calcaronea (Porifera: Calcarea) from the Barents Sea and adjacent Polar Basin, Zootaxa 5529 (3), pp. 532-550 : 544-546

Grantia asconoides ( Breitfuss, 1896)

Synonyms and citations: Sycetta asconoides ( Breitfuss 1896, 1898a, 1911; Koltun 1964). Grantia asconoides ( Breitfuss 1932; Burton 1963; Tendal 1970 (?))

Previous records: Barents Sea ( Breitfuss 1896), Volokovaya fjord ( Breitfuss 1911), north and south off Spitsbergen, north off Franz Joseph Land ( Koltun 1964)

Material examined: Barents Sea, “ Andrei Pervozvannyi ” 1899, st. 124 (69.2166N, 33.5333E), 297–313 m, Petersen trawl, 1 specimen, ZISP 10189 ; st. 108 (71.18N, 30.47E), 322 m, otter trawl, 1 specimen, ZISP 13320 . “ Andrei Pervozvannyi ” 1901, st. 631 (69.8666N, 37.9666E), 142 m, otter trawl, 1 specimen, ZISP 13321 . Polar Basin, “ Lena ” 1957, st. 18 (80.00N, 10.00E), 550 m, 1 specimen, ZISP 10191 .

Barents Sea, PINRO trawl survey 2003, st. unknown (69.9968N, 35.9596E), 142 m, temperature 2.98 °C, salinity 34.872 psu, 1 specimen, KFU-LH-2/039 .

Description: Morphology and anatomy. Sponge stipitate, with well-developed peduncle supporting an elongated, spindle-shaped body that terminates above in a single osculum surrounded by a short fringe ( Fig 9A ). The surface appears to be perforated in a sieve-like manner by the incurrent canals that are evenly distributed. Aquiferous system syconoid. Colour light yellowish (in ethanol).

Skeleton ( Fig 9C ). Atrial skeleton comprises tetractines with their basal actines oriented tangentially and the apical actine projecting into the atrium.

Subatrial skeleton composed of sagittal triactines, with their paired actines supporting the atrial wall, and the unpaired one directed towards the cortex.

Articulated tubar skeleton comprises the same kind of triactines as the subatrial one, with long unpaired actine pointing towards the cortex.

Cortical skeleton comprises several rows of subregular to sagittal triactines, with basal actines oriented tangentially and the unpaired actines directed basipetally ( Fig 9B ).

Trichoxeas arranged radially within the walls, but without protruding beyond the surface.

In the peduncle long unpaired actines of large triactines oriented basipetally. Small diactines scattered amongst them, but never protruding beyond the surface.

Spicules from the head. Trichoxeas large, with two unequal ends—one slightly fusiform and the other sharply pointed. Size: around 300 × 1 µm, often broken, similar to the small ones from the peduncle, but often longer ( Fig 9D ).

Subatrial and tubar triactines sagittal with ~ 180° angle between the straight paired actines ( Figs 9E–E 1 ). Size: paired—33–76.7–100 × 3.3–5.2–7.5 µm (n = 50), unpaired—63.8–160.6–217× 4–5.2–6.2 µm (n = 50).

Cortical triactines subregular to sagittal with stout, conical actines ( Figs 9F–F 1 ). Size: paired—47.6–85.9–137 × 5–7.2–10.7 µm (n = 50), unpaired—75.7–158.5–266.8 × 5.5–7.6–10.3 µm (n = 50).

Atrial tetractines subregular with straight, sharply pointed basal actines (fig. 9G) and with the unpaired actine always longer than the paired ones (p value <0.05). Size: paired—76–114.5–136 × 4.2–5.7–7.6 µm (n = 30), unpaired—126–179–229.6 × 5–6.5–9 µm (n = 30), apical—97.5–139.6–197 × 3.9–5.2–8.2 µm (n = 15).

Spicules from the peduncle. Trichoxeas small, similar to larger ones from the head. Size: 74–111.8–145.7 × 1–1.7–2.2 µm (n = 20). Triactines sagittal, with very short and stout paired actines, and long unpaired actine (fig. 9H). Size: paired—64.5–97.9–124.3 × 5.8–9.7–13.6 µm (n = 40), unpaired—210–366.8–485.9 × 6.7–9.7–13.75 µm (n = 40).

Remarks: Dendy and Row (1913) re-examined the type slides of S. asconoides and noted that Breitfuss had overlooked cortical triactines in his material. In specimens examined in this study, including the type specimen slides, we also found tangentially placed cortical triactines, whose occurrence, together with well-defined incurrent canals ( Rapp 2015), places the species in the genus Grantia .

There is much confusion surrounding Grantia phillipsi Lambe, 1900 , reported from around Greenland, and G. asconoides ( Breitfuss, 1896) , originally described from the north off Norway and later reported by Koltun (1964) from Svalbard and from the east off Greenland. The history of these confusions has recently been reviewed by Rapp (2015). As the author noted, “ the only clear difference [between these sponges] is the presence of slender trichoxea in G. phillipsi , especially in the peduncle ”, and “[Breitfuss] did not examine the composition of spicules in the peduncle, and he might have missed the trichoxea of the head ”, and the “ presence of trichoxeas in G. asconoides would indicate that the species are synonymous, with G. phillipsi being a junior synonym of G. asconoides ”.

We re-examined Breitfuss’s type specimen slides of G. asconoides in the Zoological Institute , St. Petersburg. Unfortunately , spicules appear to have dissolved over time in the spicule slide, but the histological sections of the head have remained and, as far as the skeleton architecture and overall complement of spicules are concerned, the type specimen is very similar to our specimens collected close to the type locality, Murman Coast ( Fig 10 ). All individuals analysed in this study proved to have trichoxeas both in the head and peduncle. The same was true for the re-examined Koltun’s specimen collected north off Svalbard, ZISP 10191 .

However, it remains extremely doubtful whether Grantia phillipsi and G. asconoides are synonyms. For Greenlandic and Icelandic specimens of Grantia phillipsi, Rapp (2015) reported tripodic atrial tetractines, with all basal rays having the same length. In specimens analysed in this study, both from Svalbard and the Murman coast, tetractines are distinctively subregular ( Fig 9G ), with the unpaired actine on average 1.5 times longer than the paired ones (p -value <0.05). Unfortunately, we could not obtain Rapp’s specimens for examination. Until this is done, the name G. phillipsi should be retained.

If the records of Grantia phillipsi and G. asconoides are considered together, the geographic distribution of these two sponges is almost continuous in the Atlantic boreo-arctic region ( Fig 10 ): from Franz Josef Land and Svalbard it extends to Kola Peninsula, and further along the shores of Norway to the west across Greenland-Iceland-Faroe ridge to Greenland, skirting eastern and northern shores of the latter. Also, if G. phillipsi and G. asconoides are not synonyms, they are sympatric species, whose distribution is overlapped along the Greenland-Iceland-Faroe ridge.

Figures

FIGURE 1. Map of sampling locations in the Barents Sea and adjacent areas.

FIGURE 9. Grantia asconoides, specimen KFU-LH-2/039. A. Habitus. B. Detail of the outer surface with cortical triactines visible, both in the head and peduncle. C. Cross-section thru the main body. D. Trichoxea. E–E1. Subatrial and tubar triactines. F–F1. Cortical triactines. G. Tetractine. H. Triactine from peduncle. Abbreviations: atr = apical actines of trtractines pointing into the atrium; cch = tubar triactines arranged radially, with long unpaired actine pointing towards the cortex.; cx = cortex.

FIGURE 10. Distribution of Grantia phillipsi and G. asconoides in the North Atlantic and Arctic. Abbreviations: purple color = specimens of G. phillipsi analysed by Rapp (2015); orange color = specimens of G. asconoides analysed in this study; star = type locality; question mark = inaccurate findings of G. asconoides.