Levinsenia marmarensis, Çinar & Dagli & Açik, 2011

Çinar, Melih Ertan, Dagli, Ertan & Açik, Sermin, 2011, Annelids (Polychaeta and Oligochaeta) from the Sea of Marmara, with descriptions of five new species, Journal of Natural History 45 (33 - 34), pp. 2105-2143 : 2132-2136

Levinsenia marmarensis sp. nov.

( Figures 9 , 10 )

Material examined

Holotype. ESFM – POL / 2010–51 , 15 April 2010, Sea of Marmara , Gelibolu, G 11, 40 ◦ 19 ′ 59 ′′ N, 27 ◦ 01 ′ 59 ′′ E, 54 m, sandy mud.

Paratypes. ESFM – POL / 2010–52 , five specimens, 15 April 2010, Sea of Marmara , Gelibolu, G 11, 40 ◦ 19 ′ 59 ′′ N, 27 ◦ 01 ′ 59 ′′ E, 54 m, sandy mud ; ESFM – POL / 2010– 53 , two specimens, 15 April 2010, Sea of Marmara , Gelibolu, G 10, 40 ◦ 31 ′ 16 ′′ N, 26 ◦ 58 ′ 46 ′′ E, 48 m, sandy mud ; ESFM – POL / 2008–83 , two specimens, 9 August 2008, Sea of Marmara , Erdek, E 1, 40 ◦ 18 ′ 42 ′′ N, 27 ◦ 46 ′ 18 ′′ E, 17 m, sandy mud ; ESFM – POL / 2008–77 , 13 specimens, 9 August 2008, Sea of Marmara , Erdek, E 6, 40 ◦ 18 ′ 49 ′′ N, 27 ◦ 46 ′ 04 ′′ E, 27 m, sandy mud ; ESFM – POL / 2008–78 , eight specimens, 9 August 2008, Sea of Marmara , Erdek, E 3, 40 ◦ 18 ′ 56 ′′ N, 27 ◦ 46 ′ 18 ′′ E, 28 m, sandy mud .

Description

Holotype incomplete, 14.75 mm long, 0.12 mm wide, with 54 chaetigers. Colour in alcohol opaque white. Body slender, wider anteriorly, filiform from midbody, gradually tapering to posterior end. Anterior segments short, much wider than long (ca. two times). Prostomium conical, with truncated anterior margin, longer than wide (length: 148 µm; width: 103 µm); ending in a cylindrical sensory organ, sometimes everted (length: 12.5 µm); a pair of nuchal organs as deep nuchal slits ( Figure 9A ). Posterior buccal lip with six longitudinal folds, extending to middle part of chaetiger 1 ( Figure 9B ). Eyes absent.

First five notopodial postchaetal lobes (prebranchial) short, rounded ca. 25 µm long ( Figure 10B ); in branchial region, from chaetiger 6 to 13, longer, digitiform; ca. 30–47.5 µm long ( Figure 10A ); in postbranchial region, shorter and thinner than those in branchial and prebranchial regions; ca. 12.5 µm on middle part of body; thinner, fingerlike (ca. 12.5 µm long) on posterior chaetigers ( Figure 10C ). Neuropodial postchaetal lobes absent ( Figure 10B,C ). Branchiae always starting from chaetiger 6, eight pairs (seven or eight pairs in paratypes), ca. 238 µm long, 40 µm wide (l / w mostly between 4.8–6); cirriform, with rounded tip, not ciliated ( Figures 9A , 10A ). Chaetigers 1–18 with only capillary chaetae. In chaetiger 3, notopodium with 13 capillary chaetae (ca. 178 µm long), neuropodium with nine capillary chaetae (ca. 158 µm long). In chaetiger 18 notopodium with seven or eight capillary chaetae (ca. 175 µm long), neuropodium with eight capillary chaetae (ca. 168 µm long). Modified neurochaetae from chaetiger 19 (19–20 in paratypes) to end of body, up to six per fascicle, arranged in a single row; strongly curved, with expanded shaft, unidentate, with a pubescent sheath on convex side of shaft, but not reaching tip of chaetae ( Figures 9C , 10C ); with two or three fine capillary accompanying chaetae. In chaetiger 20, notopodium with six capillary chaetae (ca. 178 µm long), neuropodium with three capillary chaetae (ca. 178 µm long) and one modified chaeta (15 µm long; length from node to tip). In chaetiger 35, notopodium with four capillary chaetae (ca. 181 µm long), neuropodium with two capillary chaetae (ca. 185 µm long) and three modified chaetae (22.5 µm long). In chaetiger 51, notopodium with two capillary chaetae (ca. 188 µm long), neuropodium with two capillary chaetae (ca. 190 µm long) and five modified chaetae (25 µm long). Pygidium missing.

Remarks

Levinsenia marmarensis sp. nov. is easily distinguished from the other species of the genus in having seven or eight pairs of branchiae starting from chaetiger 6. The other species of Levinsenia have different numbers of branchiae, but none has seven or eight pairs (see comparative characters of all Levinsenia species in table 2 by Aguirrezabalaga and Gil 2009).

Levinsenia gracilis minuta (Hartman-Schröder 1965) and L. oculata ( Hartman 1957) also have 8–11 pairs of branchiae, which have long and acute tips. However, these two species can be distinguished from L. marmarensis sp. nov. by the number of branchiae and the morphological features of the modified chaetae. Levinsenia gracilis minuta , which was originally described from Chile (Gulf of Punta Topocalma) at 150–240 m by Hartman-Schröder (1965), has 8–11 pairs of branchiae starting from chaetiger 6. Levinsenia marmarensis sp. nov. differs from L. gracilis minuta in having modified chaetae strongly curved with a pubescent sheath on the convex side of the shaft (slightly curved without a pubescent sheath in L. gracilis minuta ) and non-ciliated nuchal slits (ciliated nuchal slits in L. gracilis minuta ). Levinsenia gracilis minuta was subsequently described from the coast of Japan by Imajima (1973). However, the morphological features of the Japanese specimens are not congruent with the original description. For example, the Japanese specimens have three or five pairs of short branchiae, whereas the types of L. gracilis minuta have 8–11 pairs of branchiae. Therefore, we think that the Imajima’s specimens might belong to a different species of Levinsenia .

Levinsenia marmarensis sp. nov. is also similar to L. oculata , which was originally described from Southern California at 15 m by Hartman (1957), with regards to the number and shape of branchiae (seven or eight pairs in L. marmarensis sp. nov., 8–11 pairs in L. oculata , all branchiae are long and with acute tip). However, L. marmarensis sp. nov. differs from it in having no pigmentation on prostomium (brownish spots surrounding nuchal organs in L. oculata ), modified neurochaetae commencing from chaetiger 19 (from chaetigers 15–16 in L. oculata ) with small hood (without hood in L. oculata ).

Reproduction

Specimens of Levinsenia marmarensis sp. nov. collected in April have eggs in the coelomic cavities between chaetigers 30 and 48; egg diameter: 37.5–80 µm (mean: 68 µm; SD: ± 21.45, n = 20).

Etymology

This species name, marmarensis refers to the type locality (Sea of Marmara).

Distribution

Sea of Marmara, between 17 and 54 m depth.

Figures

Figure 9. Levinsenia marmarensis sp. nov. (A) Anterior end, dorsal view, holotype (ESFM– POL/2010–51); (B) anterior end, ventral view, paratype (ESFM–POL/2010–52); (C) modified neurochaetae, chaetiger 27, holotype. Scale bars: (A) 200 µm, (B) 73 µm, (C) 18 µm.

Figure 10. Levinsenia marmarensis sp. nov. (A) Right notopodium of chaetiger 10 (fifth branchial segment), anterior view, paratype (ESFM–POL/2010–52); (B) right parapodium of chaetiger 4 (prebranchial region), dorsal view, paratype; (C) right chaetiger of chaetiger 39 (postbranchial region), paratype. Scale bars (A) 100 µm, (B) 108 µm, (C) 48 µm.