Levinsenia tribranchiata, 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 : 2136-2142

Levinsenia tribranchiata sp. nov.

( Figures 11 , 12 )

Material examined

Holotype. ESFM – POL / 2008–84 , 9 August 2008, Sea of Marmara , Erdek, E 3, 40 ◦ 18 ′ 56 ′′ N, 27 ◦ 46 ′ 18 ′′ E, 28 m, sandy mud.

Paratypes. ESFM – POL / 2008–85 , 25 specimens, 9 August 2008, Sea of Marmara , Erdek, E 3, 40 ◦ 18 ′ 56 ′′ N, 27 ◦ 46 ′ 18 ′′ E, 28 m, sandy mud ; ESFM – POL / 2008–58 , one specimen, 9 August 2008, Sea of Marmara , Erdek, E 1, 40 ◦ 18 ′ 42 ′′ N, 27 ◦ 46 ′ 18 ′′ E, 17 m, sandy mud ; ESFM – POL / 2008–66 , one specimen, 9 August 2008, Sea of Marmara , Erdek, E 4, 40 ◦ 19 ′ 01 ′′ N, 27 ◦ 46 ′ 03 ′′ E, 34 m, mud ; ESFM – POL / 2010–56 , two specimens, 15 April 2010, Sea of Marmara , Gelibolu, G 3, 40 ◦ 27 ′ 17 ′′ N, 27 ◦ 04 ′ 06 ′′ E, 66 m, sandy mud .

Additional material examined

Levantine Sea: ESFM – POL / 2005–3247 , two specimens, 6 October 2005, Fethiye Bay , Sta. G 32, 36 ◦ 38 ′ 42 ′′ N, 29 ◦ 03 ′ 18 ′′ E, 100 m, mud .

Description

Holotype complete, 12.9 mm long, 0.19 mm wide, with 70 chaetigers. Colour in alcohol pale brownish. Small specimen, body thin, slender, wider anteriorly, filiform from midbody, gradually tapering to posterior end. Anterior segments short, much wider than long (ca. three times). Prostomium conical, with truncated anterior margin, longer than wide (length: 128 µm, width: 98 µm), ending in a cylindrical sensory organ, sometimes everted; a pair of nuchal organs (deep slits); eyes absent; brownish spots lateral to nuchal organs ( Figure 11A ). Posterior buccal lip with four longitudinal folds, extending to middle part of chaetiger 1 ( Figure 11B ).

First five notopodial postchaetal lobes (prebranchial) short, rounded ca. 15 µm height ( Figure 12A ); in branchial region, from chaetiger 6 to 8, long and finger-like, ca. 25–27.5 µm long ( Figure 12B ); in anterior postbranchial region, long, finger-like, ca. 30 µm long; in posterior postbranchial region (chaetiger 64), longer and finger-like, ca. 35 µm long ( Figure 12C ). Neuropodial postchaetal lobes absent ( Figure 12A–C ). Branchiae always starting from chaetiger 6, three pairs of small branchiae, ca. 65 µm long and 22.5 µm wide (l / w ratio 1.6–2.9); cirriform, with rounded tip, not ciliated ( Figures 11A , 12B ). Chaetigers 1–12 with only brown-coloured capillary chaetae. In chaetiger 4, notopodium with eight capillary chaetae (ca. 116 µm long), neuropodium with seven capillary chaetae (ca. 118 µm long). In chaetiger 12, notopodium with seven capillary chaetae (ca. 115 µm long), neuropodium with six capillary chaetae (ca. 116 µm long). Modified neurochaetae from chaetiger 13 (12 in paratypes) to end of body, up to five per fascicle, arranged in a single row, slightly re-curved, with expanded shaft, unidentate, with a developed hood on convex side of shaft, but not reaching to tip of chaetae ( Figures 11D , 12C ); with one to four fine capillary accompanying chaetae. Notopodium of chaetiger 21 with five capillary chaetae (ca. 120 µm long), neuropodium of chaetiger 21 with four capillary chaetae (ca. 126 µm long) and two modified chaetae (22.5 µm long; length from node to tip). In chaetiger 39, notopodium with four capillary chaetae (ca. 125 µm long), neuropodium with three capillary chaetae (ca. 128 µm long) and two modified chaetae (22.5 µm long). In chaetiger 64, notopodium with three capillary chaetae (ca. 136 µm long), neuropodium with two capillary chaetae (ca. 138 µm long) and five modified chaetae (25 µm long). Pygidium with a mid-dorsal lobe (ca. 55 µm long, 35 µm wide) and two ventro-lateral cirri (ca. 60 µm long, 7.5 µm wide) ( Figure 11C ).

Remarks

Levinsenia tribranchiata sp. nov. is mainly characterized by having three pairs of small branchiae on chaetigers 6–8. A similar branchial morphology was reported in Levinsenia flava ( Strelzov, 1973) from the Sea of New Guinea (Bay of Biscay) at 1750 m depth and in Levinsenia antarctica ( Strelzov, 1973) from the Kemp coast ( Antartica) at 1340 m depth by Strelzov (1973).

Levinsenia tribranchiata is closely related to L. flava in the number of the prebranchial and branchial chaetigers, and the morphology of prostomium, prebranchial and branchial lobes. However, Levinsenia tribranchiata differs from it with respect to some important characters: modified neurochaetae (commencing from chaetigers 12– 13 in L. tribranchiata vs. from chaetiger 15 in L. flava ); the ratio of the length of branchiae (1.6–2.9 in L. tribranchiata vs. 2.8 in L. flava ); the length of notopodial lobes in the branchial region (long, ca. one-half of branchiae in L. tribranchiata vs. short, ca. one-third of branchiae in L. flava ); the length and shape of notopodial lobes in the anterior part of the postbranchial region (long and finger-like in L. tribranchiata vs. short and rounded in L. flava ).

Levinsenia tribranchiata mainly differs from L. antarctica in having five prebranchial chaetigers (seven chaetigers in L. antarctica ); modified neurochaetae starting from chaetiger 12–13 (19 in L. antarctica ); a prostomium with a cylindrical sensory organ and two brownish spots (no sensorial organ and spots in L. antarctica ). Furthermore, Levinsenia tribranchiata is a shallow-water species, whereas L. antarctica is a deep-water species.

Reproduction

Specimens of Levinsenia tribranchiata sp. nov. collected in April have eggs in the coelomic cavities between chaetigers 16 and 37; egg diameter: 45–95 µm (mean 61.4 µm; SD: ± 25.03, n = 20).

Etymology

The species name tribranchiata refers to the number of branchiae (three pairs).

Distribution

Sea of Marmara and Mediterranean Sea (Levantine Sea), between 17 and 100 m depth.

Key to species of Levinsenia

1. Branchiae absent........................................................ 2

Branchiae present....................................................... 4

2. Notopodial lobes absent........ L. hawaiiensis Giere, Ebbe and Erséus, 2008

Notopodial lobes present................................................ 3

3. Modified chaetae bidentate, slightly curved................................................................ L. canariensis (Brito and Núňez, 2002)

Modified chaetae unidentate, strongly curved... L. uncinata (Hartman, 1965)

4. Three pairs of branchiae................................................. 5

More than three pairs of branchiae....................................... 7

5. Prebranchial region with five chaetigers; pigment around nuchal slits...... 6

Prebranchial region with seven chaetigers; no pigment around nuchal slits................................................ L. antarctica ( Strelzov, 1973)

6. Modified chaetae from chaetigers 12–13; long and finger-like notopodial lobes in anterior part of postbrachial region; shallow water species................................................................ L. tribranchiata sp. nov.

Modified chaetae from chaetiger 15; short and rounded notopodial lobes in anterior part of postbrachial region; deep-water species................................................................... L. flava ( Strelzov, 1973)

7. Prebranchial region with three chaetigers.................................................................... L. duodecimbranchiata Cantone, 1994

Prebranchial region with more than three chaetigers....................... 8

8. More than 17 pairs of branchiae..........................................9

Fewer than 17 pairs of branchiae........................................ 11

9. Prebranchial region with five chaetigers.................................. ...................................... L. multibranchiata ( Hartman, 1957)

Prebranchial region with eight chaetigers................................ 10

10. Two types of modified chaetae........... L. gracilis japonica ( Imajima, 1973)

One type of modified chaetae........................... L. kosswigi sp. nov.

11. Five or six pairs of branchiae........................................... 12

More than six pairs of branchiae........................................ 14

12. Prebranchial region with seven chaetigers...................................................................... L. brevibranchiata ( Strelzov, 1973)

Prebranchial region with five chaetigers.................................. 13

13. Modified chaetae strongly curved, with thin hood on convex side, not extending to chaetal tip.................................. L. demirii sp. nov.

Modified chaetae slightly curved, with thickened hood on convex side, extending to chaetal tip..................................................................... Levinsenia kantauriensis Aguirrezabalaga and Gil, 2009

14. Modified chaetae arranged in double row in posteriors chaetigers........ ...... .. ............................................... L. kirbyae Lovell, 2002

Modified chaetae arranged in single row in posteriors chaetigers.......... 15

15. Modified chaetae without hood................. L. oculata ( Hartman, 1957)

Modified chaetae with hood........................................... 16

16. Notopodial lobes on posterior chaetigers of branchial region and postbranchial chaetigers strongly reduced or not visible......................................................... L. oligobranchiata ( Strelzov, 1973)

Notopodial lobes on posterior chaetigers of branchial region and postbranchial chaetigers distinct and visible. ................................ 17

17. Prebranchial region with five chaetigers.................................. 18

Prebranchial region with more than five chaetigers....................... 20

18. Maximally eight pairs of branchiae................. L. marmarensis sp. nov.

Maximally 11–15 pairs of branchiae..................................... 19

19. Body 25 mm long; modified chaetae strongly curved with a pubescent sheath................................................... L. gracilis (Tauber, 1879)

Body 5.5 mm long; modified chaetae acicular without a pubescent sheath.................................. L. gracilis minuta ( Hartmann-Schröder, 1965)

20. Notopodial lobe tuberculate in branchial region; modified chaetae from chaetigers 27–31.. .............................. L. reducta (Hartman, 1965)

Notopodial lobe cirriform in branchial region; modified chaetae from chaetiger 21............................. L. acutibranchiata ( Strelzov, 1973)

Figures

Figure 11. Levinsenia tribranchiata sp. nov. (A) Anterior end, dorsal view, holotype (ESFM– POL/2008–84); (B) anterior end, ventral view, holotype; (C) posterior end, dorsal view, holotype; (D) modified neurochaetae, chaetiger 42, paratype (ESFM–POL/2008–85). Scale bars: (A) 200 µm, (B) 206 µm, (C) 106 µm, (D) 34 µm.

Figure 12. Levinsenia tribranchiata sp. nov. (A) Right parapodium of chaetiger 4 (prebranchial region), dorsal view, paratype (ESFM–POL/2008–85); (B) right parapodium of chaetiger 7 with branchia (second branchial segment), anterior view, paratype; (C) right parapodium of chaetiger 34 (postbranchial region), paratype. Scale bars: (A) 50 µm, (B) 46 µm, (C) 42 µm.