Marmara musculata gen. nov., 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 : 2246-2252

Marmara musculata gen. nov. et sp. nov.

( Figures 2 – 6 )

Material examined

Holotype; ESFM-CNI / 2013-1, 26 June 2013, Sea of Marmara , Y50, 41°12 ʹ 16 ʺ N, 29°07 ʹ 15 ʺ E, 10 m, muddy sand with shell fragments, specimen with visible tentacles, (dimension: 1.3 cm × 0.5 cm); Paratype; ESFM-CNI / 2013-2, 26 June 2013, Sea of Marmara , Y50, 41° 12 ʹ 16 ʺ N, 29°07 ʹ 15 ʺ E, 10 m, muddy sand with shell fragments, specimens with visible tentacles, 1.5 cm × 0.5 cm, 2 specimens; ESFM-CNI / 2013-3, 7 June 2013, Sea of Marmara Y6, 40°25 ʹ 23 ʺ N, 26°44 ʹ 03 ʺ E, 10 m, muddy sand with shell fragments, 2 specimens; ESFM- CNI/ 2013-4, 10 June 2013, Sea of Marmara , Y13, 40°44 ʹ 59 ʺ N, 27°20 ʹ 16 ʺ E, 10 m, muddy sand with shell fragments, 2 specimens; ESFM-CNI / 2013-5, 8 June 2013, Sea of Marmara , Y15, 40°19 ʹ 11 ʺ N, 27°33 ʹ 51 ʺ E, 10 m, muddy sand with shell fragments, 2 specimens; ESFM-CNI / 2013-6, 16 June 2013, Sea of Marmara , Y23, 40°23 ʹ 55 ʺ N, 28°09 ʹ 49 ʺ E, 10 m, muddy sand with shell fragments, 2 specimens; ESFM-CNI / 2013-7, 16 June 2013, Sea of Marmara , Y23, 40°24 ʹ 06 ʺ N, 28°09 ʹ 57 ʺ E, 25 m, muddy sand with shell fragments, 1 specimen; ESFM-CNI / 2013-8, 17 June 2013, Sea of Marmara , Y28, 40°57 ʹ 20 ʺ N, 28°07 ʹ 21 ʺ E, 25 m, muddy sand with shell fragments, 1 specimen; ESFM-CNI / 2013-9, 17 June 2013, Sea of Marmara , Y29, 40°32 ʹ 34 ʺ N, 28°46 ʹ 53 ʺ E, 25 m, muddy sand with shell fragments and Lithothamnion sp. , 5 specimens; ESFM-CNI /2013-10, 17 June 2013, Sea of Marmara , Y30, 40°36 ʹ 37 ʺ N, 28°56 ʹ 19 ʺ E, 25 m, muddy sand with shell fragments, 1 strongly retracted specimen but with the column very elongate, 1.5 – 5 cm × 0.5 – 0.8 cm, 5 specimens; ESFM-CNI /2013-11, 19 June 2013, Sea of Marmara , Y39, 40°39 ʹ 36 ʺ N, 29°09 ʹ 18 ʺ E, 10 m, muddy sand with shell fragments, 6 specimens; ESFM-CNI /2013 – 12, 19 June 2013, Sea of Marmara , Y39, 40°39 ʹ 41 ʺ N, 29°09 ʹ 20 ʺ E, 25 m, muddy sand with shell fragments, 1 specimen; ESFM-CNI /2013-13, 26 June 2013, Sea of Marmara , Y47, 41°04 ʹ 34 ʺ N, 29°02 ʹ 35 ʺ E, 25 m, muddy sand with shell fragments, strongly retracted specimen, cross sectioned for anatomical purposes, 0.6 – 1.7 cm × 0.6 – 0.9 cm, 5 specimens; ESFM-CNI /2013-14, 26 June 2013, Sea of Marmara , Y48, 41°07 ʹ 36 ʺ N, 29°05 ʹ 29 ʺ E, 25 m, muddy sand with shell fragments, 68 specimens; ESFM-CNI / 2013-15, 26 June 2013, Sea of Marmara , Y48, 41°07 ʹ 47 ʺ N, 29°05 ʹ 11 ʺ E, 50 m, muddy sand with shell fragments, 4 specimens; ESFM-CNI /2013-16, 26 June 2013, Sea of Marmara , Y49, 41°09 ʹ 08 ʺ N, 29°02 ʹ 40 ʺ E, 25 m, muddy sand with shell fragments, 14 specimens; ESFM-CNI / 2013-17, 24 June 2013, Sea of Marmara, BT 7, start: 40°58 ʹ 00 ʺ N, 28°46 ʹ 31 ʺ E, finish: 40° 57 ʹ 42 ʺ N, 28°47 ʹ 10 ʺ E, 25 m, muddy sand with shell fragments, 52 specimens.

Description

Two colour patterns were observed: (a) pinky or orange-like colour with white stripes along column (more conspicuous in some specimens); white stripes more obvious from capitulum till base; upper part of column and capitulum with lines of orange or reddish colour; (b) brownish colour with same stripe and line patterns described above ( Figures 2 and 3 ). Ectoderm robust, near capitulum ( Figure 4 ). In expanded condition, body with two differentiated areas: upper part with tentacles and pharynx concentrated in a budlike structure; rest of column till base constituting a thin cord-like structure; in strongly retracted specimens, pedal disc enlarged and attached to stones or shell fragments (see Figures 2 and 3 ). Conspicuous muscular belts of endodermic musculature present along column and capitulum ( Figure 4 ). No scapulus, but difficult to determine it in retracted specimens. Tentacles retracted in many specimens; 135 tentacles present, arranged in six cycles 6 + 6 + 12 + 24 + 48 + 96; last one being incomplete. Four or five mesentery cycles maximally with 68 pairs; last cycle being incomplete ( Figures 4 and 5 ). Two pairs of directive mesenteries and two syphonoglyphs. Two or three first cycles of perfect mesenteries with two pairs of directives; third or fourth cycle of imperfect microneme mesenteries with small retractor developments; incomplete fourth or fifth cycle of micronemes without retractor development: 6 + 6 + 12 + 24 + 48. Short pharynx; cynclides located near capitulum, also present in pedal disc. Sphincter mesogloeal, located in upper part of column; in thicker part of sphincter, width of mesogloea reaching up to 100 μm. Strong and restricted reniform retractors, occupying almost whole or half of mesentery ( Figure 4 ). Parietobasilar distinct, but not well developed.

Cnidom

The types of nematocysts along the body of Marmara musculata sp. nov. are shown in Table 1 and Figure 6 . Several capsules of larger acontiae spirulae (26 – 32 µm × 3 µm) were found sporadically in the filaments of this new species. Spirula 2 from tentacles ( Figure 6 (d)) may be more common, but small capsules might have been overlooked among the tissue. In this species, almost all capsules are common or very common.

Remarks

Marmara musculata sp. nov. has a reduced base and elongated retractor muscles. Such characters were also reported in Sagartianthus indosinensis Carlgren 1843 , but its morphology is quite different from Marmara musculata sp. nov. and it does not have any conspicuous muscular bands along the column (see Fautin 2013). The

et sp. nov. Frequency: vc: very common; c: common; rc: rather common; uc: uncommon; r: rare.

cnidome of S. indosinensis is somewhat similar to that of M. musculata sp. nov. (see Carlgren 1943), but there are some consistent differences regarding the categories in each tissue; there are more categories in the body wall of M. musculata sp. nov. Anthothoe a ffi nis ( Johnson 1861) has a morphological adaptation to live on mollusc shells and presents a very special cnidome (see Ocaña 1994). Other genera living on shells occupied by decapods are Carcinactis ( Uchida 1960) and Verrillactis ( England 1971) (see Uchida 1960; England 1987). All of them represent important morphological differences and also have three nematocyst categories (two spirulae and one penicilli in the case of Carcinactis and Verrillactis ) in the acontia, whereas in the new genus there are two nematocyst categories (one spirulae and one penicilli) in the acontia. The species belonging to genus Actinothoe are typical to rocky bottoms (see Ocaña 1994; Ocaña et al. 2015) and also have quite different biometrical features of the cnidome (which is longer and wider). Gymnophellia hutchingsae England 1992 , which was originally described from southern China Sea (1992), was placed into the family Isophelliidae , but according to the anatomical and cnidom characteristics of the species, it should be placed into the family Sagartiidae . The anatomy of G. hutchingsae greatly differs from that of M. musculata sp. nov.; moreover the former species has more cnidom categories in several tissues (among others: one spirulae more in the acontiae; one penicilli more in the filaments) than those in the latter species. There is no other species belonging to Sagartiidae in the Mediterranean that is morphologically similar to M. musculata sp. nov.

Habitat

This species was found living on sandy mud bottoms with the base attached to stones or shell fragments from 10 m to 50 m depths.

Etymology

The species name comes from the highly developed musculature present in the species.

Figures

Figure 2. Marmara musculata sp. nov. (a–d) Retracted and protruded fixed specimens showing characteristic colour pattern and external morphology. Scale bar: 5 mm.

Figure 3. Marmara musculata sp. nov. (a–c) Live specimens showing different colour patterns and morphology. Scale bar: 5 mm.

Figure 4. Marmara musculata sp. nov. (a) Transversal section of pharynx showing strong retractors, thick mesogloea and a very poor ectodermal development. (b) Longitudinal section of body showing the placement of the sphincter concentrated in the upper part of the column. Scale bar: a = 0.8 mm, b = 1.2 mm. Abbreviations: s: sphincter; si: syphonoglyphs; ph: pharynx; m: mesogloea; ec: ectoderm; en: endoderm: fi: filaments; t: tentacles; mi: microcnemes; ma: macrocnemes; r: retractors; d: directives.

Figure 5. Marmara musculata sp. nov. (a, b) Retractors below the pharynx level; (c, d) pharynx level with retractors and gonads; (e) details of retractors and gonads. Scale bar: a, b = 1 mm, c = 2 mm, d = 1.6 mm, e = 0.8 mm.

Figure 6. Marmara musculata sp. nov. Cnidom morphology in different parts of the body. (a) Spirocyst; (b) penicilli B; (c) spirulae 1; (d) spirulae 2; (e) penicilli A; (f) spirulae 1; (g) spirulae 2; (h) penicilli A; (i) penicilli B; (j) spirulae; (k) penicilli B; (l) spirulae 1; (m) spirulae 2; (n) penicilli B; (o) spirulae. Scale bar: 13 µm.