Geodia hentscheli, CARDENAS ET AL., 2010

Cárdenas, Paco, Rapp, Hans Tore, Klitgaard, Anne Birgitte, Best, Megan, Thollesson, Mikael & Tendal, Ole Secher, 2013, Taxonomy, biogeography and DNA barcodes of Geodia species (Porifera, Demospongiae, Tetractinellida) in the Atlantic boreo-arctic region, Zoological Journal of the Linnean Society 169 (2), pp. 251-311 : 272-278

GEODIA HENTSCHELI CÁRDENAS ET AL., 2010

DEPRESSIOGEODIA P HENTSCHELI (PhyloCode SPECIES NAME)

( FIGS 11–14 , TABLE 3)

Sidonops mesotriaena, Hentschel, 1929: p. 865 (junior homonym by Cárdenas et al., (2010)).

Geodia mesotriaena, Burton, 1934: p. 6 ; Koltun, 1964: p. 147; 1966: p. 52; Barthel & Brandt, 1995: p. 223; Klitgaard & Tendal, 2004: p. 57.

Geodia hentscheli, Cárdenas et al., 2010: p. 89 ; Cárdenas et al., 2011: table S1; Tangen, 2011: p. 47.

Misidentification:

Geodia nodastrella, Burton, 1934: p. 6 .

Type locality and deposition of types: Hentschel (1929) explicitly designated a holotype ( ZMB Por 7549 has an old label saying ‘ Sidonops mesotriaena n. sp. Typ’) from north of Spitsbergen , station 41, 81°20′N, 20°30′E, 1000 m , 11 th of August 1898. Paratypes are ZMB Por 7545–7546, 7548, 7550–7551, 8421, all from st. 41 and st. 40 (81°22′N, 21°21′E, 650–1000 m) .

External morphology and cortex: The body is spherical ( Fig. 11A–D ), up to about 15 cm in diameter. The colour alive is white to light yellow or brownish. With the use of ROVs, we found that this species can be entirely covered with long spicules, making them look very fury ( Fig. 11D ), which may be lost when dredged, and specimens then seem completely smooth ( Fig. 11A–C ). Some specimens are budding ( Fig. 11C ), and buds are usually columnar with sometimes a small peduncle. A preoscule opening, usually narrow (up to 1.8 cm in diameter), occasionally up to three, is found on the top side. This preoscule is even observed in young specimens (8 mm in diameter). These preoscule openings are often surrounded by a narrow elevated ring with a thickened cortex. Sometimes, in large specimens, the preoscule opening ‘sinks’ in the sponge body (one such specimen can be seen in the upper right corner of Fig. 11B ). As in G. barretti , uniporal oscules are concentrated in the preoscule ( Fig. 11E ); the cortex there is without sterrasters, and ridges of microxeas and strongylasters surround oscules. These ridges can be much more developed than in G. barretti . The cribriporal pores are scattered over the sides of the body (total diameter of the sieve: 0.1–0.2 mm) ( Fig. 11F ). The sterraster layer is elastic, 0.25–1.4 mm thick ( Fig. 12 ), with the ectocortex poorly developed (0.1 mm thick, in holotype) ( Fig. 12B ) to well developed (0.3 mm thick) ( Fig. 12C ).

Description of type material: The holotype ZMB Por 7549 is cut into four pieces. For this study, we have examined only a small slice of the paratype ZMB Por 7551. Thick sections of ZMB Por 7551 made during this study ( Fig. 12A ) are now stored at the ZMB. Figure 13 shows SEM pictures of the spicules of the paratype ZMB Por 7551.

Spicules ( Fig. 13 , Table 3): Megascleres: (a) oxeas I, straight or bent, length: 1200–5175 Mm; width: 29–82 Mm. (b) Oxeas II, usually straight (sometimes slightly bent), sometimes slightly centrotylote, length: 142–610 Mm; width: 5–23 Mm. (c) Ortho- to dichotriaenes, rhabdome length: 252–4060 Mm (maximum length was measured by Hentschel, 1929); width: 22–145 Mm; orthotriaene clad length: 196–835 Mm; protoclad length: 60–520 Mm; deuteroclad length: 96–492 Mm. (d) Anatriaenes, rhabdome length: more than 6000 Mm; width: 17–43 Mm; clad length: 90–308 Mm. (e) Meso/protriaenes, rhabdome length: up to 4185 Mm; width: 17–36 Mm; clad length: 87– 224 Mm; central clad length: 98–196 Mm. Microscleres: (f) sterrasters, usually spherical, some are very irregular, 56–102 Mm in diameter; thickness: 55–80 Mm; hilum: 12–20 Mm. Rosettes are made of 3–7 rays, covered with warts. Rosette diameter: 5–6 Mm. (g) Strongylasters to sphero-strongylasters, spiny, 4–22 Mm in diameter. (h) Oxyasters, spiny, with a more or less inflated centrum, with 4–20 rays, diameter: 10–62 Mm.

DNA barcodes: GenBank accession nos. HM 592671 , EU442197 (Folmer COI): we have sequenced COI from specimens from northern Iceland (1), the Schultz Massive Seamount in the Greenland Sea (4), and the Davis strait (1): the Folmer COI is identical in all these specimens. No. EU552083 (28S, C1-D2 domains): we have sequenced 28S from two specimens from the Schultz Massive Seamount in the Greenland Sea, and no variation was observed. No. KC481226 (18S), obtained from UPSZMC 78042 (Schultz Massive Seamount) .

Distribution ( Fig. 14 ): Geodia hentscheli is an Arctic species. The species has been recorded at depths of 130–2000 m, at temperatures of –1.76 (eastern Greenland) to 4.5 °C (west of Iceland and Reykjanes Ridge). The shallowest records (less than 200 m deep) come from the Canadian Ice Island at 81°N ( Wagoner et al., 1989) and eastern Greenland ( Burton, 1934; Koltun, 1964), the deepest records being off eastern Greenland, at temperatures of –1.76 to 0.4 °C. This species has not been found off Newfoundland.

Biology: Budding seems to be fairly common in this species ( Fig. 11C ). The isopod Caecognathia robusta (G. O. Sars, 1879) is a common epibiont living in the preoscule of this species ( Barthel & Brandt, 1995). We have observed very few sponges living on the fur of G. hentscheli (e.g. Calcarea spp.).

Distinctive characters: External morphology: the almost spherical form with one narrow preoscular cavity on top. Also, usually there is a thickening of the cortex just around the oscule, and there might be more or less high ridges between the small oscules (inside the preoscule). Spicules: on average, small size and ‘bumpiness’ of the sterrasters, some sterrasters are very irregular, short and thick microxeas, large and sometimes irregular strongylasters. But one or all of these characters may be absent.

Remarks: We examined specimen B331 ( ZMO) from East Greenland (137 m depth), identified as G. nodastrella by Burton (1934). A misidentification was suspected as G. nodastrella is a typical Lusitanian deep-sea species, never formerly described from arctic waters. B331 ( ZMO) is a small spherical specimen (8 mm in diameter) with two bundles of long spicules (mainly mesoprotriaenes) sticking out from it and a 0.5-cm-thick cortex. The presence of one very small preoscule opening already suggests that this is not G. nodastrella (which has cribriporal pores and oscules, no preoscules). Furthermore, the spicules clearly match those of G. hentscheli . Burton (1934) was probably misled by the strongylasters which, in Greenland and Icelandic specimens, can become large sphero-strongylasters (up to 22 Mm in diameter in this specimen, larger than those measured in Table 3). We also examined the larger specimen B330 ( ZMO) from the same catch and identified by Burton (1934) as G. mesotriaena (now hentscheli ); this identification is correct.

In Table 3, the maximum size of oxyasters measured is 38 Mm. But we also examined more specimens and we found that oxyasters could reach sizes of 48 Mm ( ZMBN 85205 , Iceland, 604 m depth), 55 Mm ( UPSZMC 78266 , Davis Strait , 847 m depth) or even 62 Mm (PC18, Iceland, 800 m depth). These large sizes of oxyasters are not mentioned by Koltun (1966). We also noted that the NEA specimens have oxyasters with fairly thin actines (2 Mm thick) whereas the three specimens from Davis Strait (PA2010-set 155) we examined have oxyasters with less numerous, thicker actines (up to 5 Mm thick). There is also quite Means are in bold; other values are ranges; N = 30 unless stated otherwise in parentheses, or unless measurements come from other studies. A dash indicates that this measurement is not given in the literature. n.f., not found; n.o., present but not observed in the sample in our possession, or broken .

a lot of variation of the strongylasters (more so than in G. barretti ). As we noted earlier, they can be fairly large and fairly irregular, and their actines can also be so small that they look like irregular spheres. We also noted that some specimens from Davis Strait (e.g. UPSZMC 78266) have particularly large spicules overall and a much thicker cortex (1–1.4 mm) than other specimens we examined ( Table 3), probably because they are larger specimens (> 10 cm). The smaller specimen UPSZMC 78267 ( Fig. 11A ), c. 3 cm in diameter, from the same station has a cortex of 0.55 mm. So cortex thickness may increase with size of specimens.

Based on their morphology, G. barretti and G. hentscheli have previously been considered sister species ( Koltun, 1966): their spicule and external morphologies are very similar so that they can be easily confused. But spicule measurements suggest that, on average, G. hentscheli has smaller sterrasters, thicker and shorter oxeas II, and larger somewhat more irregular strongylasters than G. barretti , but their ranges overlap so that these characters are not sufficient. Orthotriaenes are more common in G. hentscheli than in G. barretti . At all depths, G. hentscheli sterrasters are usually spherical whereas G. barretti sterrasters tend to become elongated in the NEA below 1000 m depth (but not in the NWA). Also, G. hentscheli sterrasters may have a bumpier surface than in G. barretti , due to slightly larger rosettes with more spines, but again, this character is not always present or easy to distinguish for a non-specialist. On the other hand, G. hentscheli sterrasters can often be irregularly developed ( Fig. 13F ), and this is never observed in G. barretti . As for external morphology, confusion is still possible because G. barretti can sometimes have a subspherical shape with a narrow preoscule as well ( Fig. 7A ). Genetically G. barretti and G. hentscheli are clearly different: 6–7 bp difference in the COI Folmer fragment, 8 bp difference in the 28S (C1-D2) fragment, and even 1 bp difference with 18S.

Figures

Figure 7. External morphology of Geodia barretti Bowerbank, 1858. A, specimen PC10 (fixed in ethanol) from Korsfjord, Norway; specimen is 10 cm large. B, specimen ZMBN 89716 just after dredging from north of Spitsbergen, 215 m depth; specimen is 30 cm long. C, specimen cut in half just after dredging from the Polarstern ARK-XXII/1a, 2007, field# 40-4(3); specimen is 14 cm large. D, specimen PC72 just after dredging from Korsfjord, Norway, at 200–400 m depth; specimen is 30 cm long. E, specimen in situ at Traenadjupet, northern Norway, 66°58′N, 11°7′E, 292 m depth, later collected under field# 27-1(11) (picture taken by J. Schauer, Polarstern ARK-XXII/1a, 2007). F, specimen PC359 just after dredging at 1818 m depth off western Ireland; specimen is 16 cm large. G, uniporal oscules inside the preoscule of ZMBN 89722 (from Spitsbergen); each oscule has a separate sphincter. Scale bar: 1 mm. H, cribriporal pores of ZMBN 89715 (from Spitsbergen). Scale bar: 1 mm.

Figure 11. External morphology of Geodia hentscheli Cárdenas et al., 2010. A, specimen UPSZMC 78266 (fixed in ethanol) from Davis Strait, 847 m depth. B, specimens just dredged in the Davis Strait at 847 m depth (photo courtesy of DFO Canada Central and Arctic Region). C, specimen from Ingolf Exp., st. 78, south of Iceland, 1462 m depth (fixed in ethanol). The arrows point at the buds. D, specimen PC221 (fixed in ethanol) from the Schultz Massif, 1262 m depth. E, cross-section in the preoscule of specimen UPSZMC 78266 (Davis Strait, 847 m). Note the massive and irregular ridges between the oscules. F, cribriporal pores of PC16 (northern Iceland, 604 m). Scale bars: A: 5 mm; C, E: 1 cm; F: 0.2 mm.

Figure 12. Thick sections of Geodia hentscheli Cárdenas et al., 2010. A, paratype ZMB Por 7551. B and C, Ingolf Exp., st. 78, south of Iceland, 1462 m depth. D, ZMBN 77925, lower slope of the Schultz Massive Seamount, 1997 m. Scale bars: A, B and D: 500 Mm; C: 300 Mm.

Figure 13. Spicules of the paratype ZMB Por 7551 of Geodia hentscheli Cárdenas et al., 2010. A, microxeas. Arrow points at centrotylote portion. B, oxyasters. C, strongylasters. D, sterrasters and oxyaster. E, close-up on the hilum of a sterraster. Notice the warty rosettes. Scale bar: 2 Mm. F, irregular sterraster.

Figure 14. Distribution of Geodia hentscheli Cárdenas et al., 2010 (map made with GeoMapApp, http://www.geomapapp.org). T, type locality.