Virgularia sp.

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 : 2275-2278

Virgularia sp.

( Figure 20 )

Material examined

ESFM-CNI /2013-26, 8 June 2013, Sea of Marmara , Y12, 40°39 ʹ 44 ʺ N, 27°17 ʹ 00 ʺ E, 25 m, sandy mud with Amphiura fi liformis (O. F. Müller 1776), 2 specimens; ESFM-CNI /2013 – 27, 9 June 2013, Sea of Marmara , Y16, 40°18 ʹ 39 ʺ N, 27°45 ʹ 43 ʺ E, 25 m, sandy mud with A. fi liformis, 4 specimens; ESFM-CNI /2013-28, 12 June 2013, Sea of Marmara , Y20, 40° 57 ʹ 09 ʺ N, 27°54 ʹ 46 ʺ E, 50 m, sandy mud with A. fi liformis, 1 specimen; ESFM-CNI /2013- 29, 15 June 2013, Sea of Marmara ,Y21, 40°29 ʹ 54 ʺ N, 27°58 ʹ 28 ʺ E, 25 m, sandy mud with shell fragments, 1 specimen; ESFM-CNI /2013-30, 17 June 2013, Y28, 40°57 ʹ 20 ʺ N, 28° 07 ʹ 21 ʺ E, 25m, sandy mud, 1 specimen; ESFM-CNI /2013-31, 19 June 2013, Sea of Marmara ,Y40, 40°41 ʹ 22 ʺ N, 29°20 ʹ 58 ʺ E, 25 m, sandy mud with shell fragments, 1 specimen; ESFM-CNI /2013-32, 8 June 2013, Sea of Marmara , BT-2, start: 40°20 ʹ 34 ʺ N, 27° 34 ʹ 33 ʺ E, finish: 40°20 ʹ 33 ʺ N, 27°35 ʹ 06 ʺ E, 30 m, 300 specimens, sandy mud.

Description

Colonies elongate, slender, most of them with rachis and peduncule, although tips of all specimens broken; maximum length 46 cm long ( Figure 20 (a), 20(b)). Total number of leaves 170; number of leaves with fully developed polyps 138. Number of polyps per leaf ranging from 2 – 3 (on 10 – 15 cm colonies) to maximally 6, but mainly 5 on colonies of 20 – 46 cm long ( Figure 20 (c), 20(d)). Polyps 1.4 – 2 mm long, 0.5 mm wide (maximum). Colour brownish to salmon in recently collected material. Sclerites absent.

Remarks

The longest specimen (46 cm long) has 5 polyps per leaf and exceptionally 6. Most of the medium and small sized colonies have 2 – 3 polyps per leaf. We first identified the specimens as Scytaliopsis dijiboutiensis Gravier, 1906 , but the inadequate description of this genus forced us to reconsider our argument and eventually we transferred the specimens to the genus Virgularia . Perhaps Scytaliopsis could form a group with other species of Virgularia with low number of polyps per leaf, but, for now, Scytaliposis is an ill-defined genus that could easily be placed within Virgularia . We found enough evidence that our specimens do not belong to Virgularia mirabilis (O.F. Müller 1776) , which is known from the Mediterranean Sea. Williams (1995, 125; 1999, 46) catalogued more than 20 valid species of Virgularia and, according to this author, 56 species were referable to this genus (see Kükenthal 1915, 71 – 80). Thirteen of 14 species included in Kükenthal (1915) were considered as valid species by Williams (1999). Nevertheless Kükenthal (1915) included brief comments about 14 other dubious Virgularia species collected from different habitats and locations. Some of these species were not well defined in the scientific literature (see Kükenthal 1915) or even their validities were rejected by Williams (1999), but some of them were referable to Virgularia species after all. Having a low number of polyps per leaf in Virgularia sp. represents a morphological affinity to Virgularia gracillima Kölliker 1880 (4 polyps per leaf), Virgularia ceylonensis (6 polyps per leaf) and Virgularia studeri (4 – 5 polyps per leaf). According to Kükenthal (1915), most of the Virgularia species can be identified based on the number of polyps, but in the case of Virgularia mirabilis there are two different morphological varieties recognized in the scientific literature (see Tixier- Durivault 1961b, 257) based on the number of polyps per leaf. Therefore, the identifications of Virgularia species and specially those showing similar appearance with V. mirabilis seem to be difficult. Even our colonies from the Sea of Marmara could be V. mirabilis typica with 3 to 10 polyps per leaf described by Tixier-Durivault (1961b). However, the large colonies from the Sea of Marmara (more than 40 cm long) never have more than six polyps per leaf. López-González et al. (2001) observed 6 – 8 polyps per leaf in a fragment of 13 cm of V.mirabilis from Guinea Gulf and polyps were retracted into fleshy calyces. Williams (1990, 1995) found 5 – 12 polyps per leaf in colonies of up to 9.5 cm long collected from South Africa, and Manuel (1981) reported up to 12 polyps per leaf on the British specimens. Virgularia mirabilis usually has more than 6 polyps per leaf, but the largest specimens from the Sea of Marmara had maximally 6 polyps per leaf, but in most of the specimens the leaves possessed 3 to 5 polyps. The polyp leaves of the Sea of Marmara specimens are not situated next to each other, whereas V. mirabilis represents polyp leaves which are placed next to each other as a rule (see Williams 1990, 90, Tixier-Durivault 1961b, 256; Manuel 1981, 54). However, a disagreement in this rule was noted on the specimens studied by Tixier-Durivault (1961b). The polyps not placed next to each other is a common shared character between Virgularia sp. from the Sea of Marmara and Virgularia tuberculata Marshall 1887 (with tubercles on the terminal rim of the calyx sensu Williams 1990), but the absence of the tubercles on the calyx of Virgularia sp. from the Sea of Marmara as well as the distributional pattern ( V.tuberculata is a cold water species, but also found in West Africa coast, see Tixier-Durivault 1961b; López-González et al. 2001) makes significant differences between these species. We think that the specimens from the Sea of Marmara do not belong to Virgularia mirabilis and could possibly be a new species. However, we do not want to increase the problem into the genus and require examination of some more Virgularia mirabilis specimens from different regions, and other similar species from the Indo-Pacific region with a few number of polyps per leaf to reach a reliable conclusion.

Habitat

It is a common species on sandy mud bottom from the Sea of Marmara (depth range, 25 – 50 m).

Figures

Figure 20. Virgularia sp. (a) Specimens of Virgularia sp.; (b) peduncle; (c) rachis with polyp leaves; (d) authozooids and siphonozooids. Scale bar: a = 20 cm; b = 8 mm, c = 5 mm, d = 1.5 mm.