Scolanthus mediterraneus, Ocaña & Çinar, 2018

Ocaña, Oscar & Çinar, Melih Ertan, 2018, Descriptions of two new genera, six new species and three new records of Anthozoa (Cnidaria) from the Sea of Marmara, Journal of Natural History 52 (35 - 36), pp. 2243-2282 : 2263-2266

Scolanthus mediterraneus sp. nov.

( Figures 13 and 14 )

Material examined

Holotype, ESFM-CNI/2013-22 , 17 June 2013, Sea of Marmara , Y29, 40°32 ʹ 22 ʺ N, 28° 46 ʹ 59 ʺ E, 10 m, sandy mud with shell fragments, 1 cm long, cross sectioned to study the anatomy and cnidom ; Paratypes, ESFM-CNI/2013-23 , 24 June 2013, Sea of Marmara , Y34, 40°57 ʹ 13 ʺ N, 28°51 ʹ 25 ʺ E, 10 m, sandy mud with Lithothamnion sp ., specimens of 0.6 – 1.3 cm long with the aboral end naked and tentacles expanded, 4 specimens; Paratype, ESFM-CNI /2013-24, 17 June 2013, Sea of Marmara , Y29, 40°32 ʹ 22 ʺ N, 28°46 ʹ 59 ʺ E, 10 m, sandy mud with shell fragments, on specimen of 1 cm long, 4 specimens; Paratype, ESFM-CNI /2013-25,07 June 2013, Sea of Marmara , Y8, 40°25 ʹ 15 ʺ N, 27°03 ʹ 49 ʺ E, 10 m, sandy mud with shell fragments, specimens 0.2 -0.3 cm long, 5 specimens.

Description

Small anemone (5 – 25 mm long); column, with exception of naked scapulus, covered with cuticle including physa-like structure developed at end of body wall ( Figure 13 (a), 13(d)). Sixteen tentacles arranged in two cycles; small rounded tubercles (nemathybomes) arranged in eight cycles. Eight mesenteries; retractor developments present only in six or seven of them. Strong reniform restricted retractors with a maximum of 20 – 25 processes ( Figure 13 (e), 13(f)). Short pharynx concentrated in upper part of column at scapulus level.

Cnidom

A survey of the cnidom is summarized in Table 5. We did not find any category of penicillin ( Figure 14 ).

Remarks

The genus Scolanthus is characterized by the presence of nemathybomes on the scapus (including the aboral zone) and the absence of a real physa. Scolanthus mediterraneus sp. nov. is morphologically similar to S. callimorphus Gosse 1853 ; however, the latter species (up to 140 mm in length and 12 mm diameter) is much larger than the former species (5 – 25 mm long). In addition, the presence of penicilli in the filaments of S. callimorphus and its larger nematocysts (see Carlgren 1931, 24; Schmidt, 1979: 216) distinguish it from Scolanthus mediterraneus sp. nov. Searching for other species merged within the genus we found several species from different locations (see Mc Murrich 1893; Pax 1924; Carlgren 1931) and also new descriptions of two small sized species from California (see Daly and Ljubenkov 2008). These species hardly reach 1 – 4 cm long and show some external resemblances with S. mediterraneus sp. nov. Scolanthus armatus Carlgren 1931 , originally described from Indonesia, is a small sized species and quite different from S. mediterraneus sp. nov., because of the presence of elongated retractors and larger nematocysts in its tentacles and nemathybomes (see Carlgren 1931). The description of S. curacaoensis Pax 1924 from the Caribbean Sea is not complete, but the retractor muscles are very different from those of our specimens (see Pax 1924). Scolanthus intermedia Mc Murrich 1893 , originally described from Tierra del Fuego and Antarctica, shares a similar morphological feature with S. mediterraneus sp. nov. (contracted body shape with the pronounced hollow along the column), but differs from it in having less developed retractor muscles. The retractor muscles of Scolanthus nidarosiensis ( Carlgren 1942) are similar to those of S. mediterraneus sp. nov., but the cnidom features represent some consistent differences in these two species: (1) penicilli is present in S. nidarosiensis , but absent in S. mediterraneus sp. nov.; (2) much longer and thinner nematocysts were found in the nemathybomes and pharynx of S. nidarosiensis . The retractor muscles in Scolanthus scamiti Daly and Ljubenkov 2008 , originally described from California, are greatly enlarged, whereas they are reniform-shaped in S. mediterraneus sp. nov. The Californian specimens also have penicilli (absent in S. mediterraneus sp. nov.) and shorter nematocyst dimensions. The retractor muscles in S. triangulus Daly and Ljubenkov 2008 (also known from California) represent a poor development, whereas S. mediterraneus sp. nov. has rather strong reniform retractors. Both species do not have penicilli, but the lengths of cnidom and their distributions in tissues are quite different between them (see Daly and Ljubenkov 2008).

Habitat

This species was found in sandy mud bottom at 10 m depth.

Etymology

The species name is dedicated to the Mediterranean Sea.

Figures

Figure 13. Scolanthus mediterraneus sp. nov. (a–d) Preserved specimens showing the whole bodies with cuticle, physa, tentacles, scapulus and nemathybomes; (e, f) retractors under the pharynx level. Scale bars: a = 2.4 mm; b, c = 2.2 mm; d = 1 mm, e, f = 1.3 mm.

Figure 14. Scolanthus mediterraneus sp. nov. Cnidom morphology in different parts of the body. (a) Spirocyst; (b) spirulae 1; (c) spirulae 2; (d) spirulae 1; (e) spirulae 2; (f) spirulae 1; (g) spirulae 2; (h) spirulae. Scale bar: 13 µm.