Paradoneis longifurcata, Erdoğan-Dereli & Çinar, 2019

Erdoğan-Dereli, Deniz & Çinar, Melih Ertan, 2019, The genus Paradoneis (Annelida: Paraonidae) from the Sea of Marmara, with descriptions of two new species, Zootaxa 4686 (4), pp. 465-496 : 481-495

Paradoneis longifurcata n. sp.

urn:lsid:zoobank.org:act:CEAA1898-85A2-4786-860B-F95778394DDA

Material examined. Holotype, ESFM–POL/2013–1100 , 16 June 2013, station Y24, 41°03’08’’N, 28°08’44’’E, 25 m, maerl bed (muddy sand with Lithothamnion sp.)

Paratypes. 167 specimens: ESFM-POL /2012-497, 21 October 2012, station K18, 40°50’26’’N, 29°07’33’’E 15-30 m, serpulid reef, 1 specimen; ESFM-POL /2013-1364, 08 June 2013, station Y9, 40°28’09’’N, 27°11’14’’E, 50 m, mud, 2 specimens; ESFM-POL /2013-1377, 09 June 2013, station Y17, 40°39’58’’N, 27°41’08’’E, 50 m, mud, 1 specimen; ESFM-POL /2013-1382, 10 June 2013, station Y18, 40°54’28’’N, 27°33’24’’E, 100 m, mud with shell fragments, 2 specimens; ESFM-POL /2013-1383, 12 June 2013, station Y19, 40°56’10’’N, 27°44’16’’E, 100 m, muddy sand, 4 specimens; ESFM-POL /2013-1101, 16 June 2013, station Y22, 40°23’22’’N, 27°59’46’’E, 50 m, mud, 1 specimen; ESFM-POL /2013-1103, 16 June 2013, station Y24, 41°03’08’’N, 28°08’44’’E, 25 m, maerl bed, 17 specimens; ESFM-POL /2013-1391, 16 June 2013, station Y24, 41°00’16’’N, 28°07’50’’E, 50 m, muddy sand with shell fragment, 92 specimens; ESFM-POL /2013-1392, 15 June 2013, station Y24, 40°57’20’’N, 28°07’21’’E, 100 m, muddy sand with shell fragments, 5 specimens; ESFM-POL /2013-1104, 16 June 2013, station Y25, 40°24’48’’N, 28°20’41’’E, 25 m, sandy mud with Amphiura filiformis , 1 specimen; ESFM-POL /2013-1112, 17 June 2013, station Y29, 40°32’39’’N, 28°46’42’’E, 50 m, muddy sand, 1 specimen; ESFM-POL /2013-1113, 17 June 2013, station Y29, 40°33’32’’N, 28°44’58’’E, 100 m, muddy sand, 17 specimens; ESFM-POL /2013-1408, 14 June 2013, station Y31, 40°56’40’’N, 28°25’15’’E, 100 m, sandy mud with shell fragments, 5 specimens; ESFM- POL/2013-1418, 20 June 2013, station Y41, 4043’18’’N, 2924’58’’E, 100 m, mud, 1 specimen; ESFM-POL /2013- 1116, 20 June 2013, station Y42, 40°45’43’’N, 29°29’39’’E, 50 m, mud, 17 specimens.

Description. Holotype complete, 6.56 mm long (4.9–13.6 mm long in complete paratypes), 0.20 mm wide at chaetiger 10 (0.16-0.29 mm wide in paratypes), with 60 chaetigers (40–90 chaetigers in complete paratypes). Color of holotype in alcohol light yellowish (yellowish and dull white in paratypes) ( Fig. 15A ). Body thin, cylindrical; prebranchial, branchial and postbranchial regions similar in width, gradually thinner towards posterior region ( Figs 13A , 14A ; 15A ). Antero-dorsal side of body slightly swollen from chaetiger 1 to chaetiger 5 ( Figs 13A ; 15A ). A dense ciliary band on mid-dorsal transversal line of each prebranchial and branchial chaetigers ( Fig. 16A ; 18A ); ciliary bands absent on ventral side ( Figs 16B ; 18B ). Prostomium triangular; slightly longer than wide (length/ width: 1.08); anterior part rounded. A semicircular eversible palpode placed on anterior end of prostomium, bear- ing irregularly arranged pores with flexible cilia ( Figs 14A ; 18A, B ); eyes present on prostomium. An oval lateral organ present on lateral sides of prostomium and peristomuim, with about 60 irregular pores ( Figs 17 A–C; 18A, C). One complete ciliated band, termed as nuchal associated ciliary band (nacb), connecting ventrally one nuchal organ to another and leaving a gap between them in dorsal side ( Fig. 18C ). Peristomium fused with prostomium; starting point posterior to nuchal organs; highly reduced on dorsal view but much more developed on ventral side ( Fig. 18 A–C). A short additional transversal ciliary band existing on dorsal side of prostomium, just anterior to nu- chal organs ( Fig. 18C ). A pair of nuchal organs as deep slits placed dorso-laterally on posterior end of prostomium; cilia in nuchal organ well extending out of slits ( Figs 16C ; 17C ; 18C ); without pigmentation in holotype, but with two brownish spots on posterior part in most paratypes ( Figs 14A ; 15C ). Mouth with eight buccal lips; two lips on anterior part, six lips on posterior part, extending to anterior margin of chaetiger 2 ( Fig. 18B ). Proboscis without lobes, with dense ciliation ( Figs 15B ; 16B ). Lateral sense organs as an oval ridge located on ventral side of noto- podial postchaetal lobes in each chaetigers ( Figs 18A ; 19C ; 20A ; 21 A–C); with flexible cilia distinctly protruding from opening or embedded into pore ( Fig. 20A ), showing its retractable character; lateral sense organs starting from chaetiger 1 to end of body; oval shaped with irregularly clustered pores; with ca. 8–9 pores (long axis: ca. 4 μm) in prebranchial region, with ca. 16–18 pores (long axis: 4–5 μm) in branchial region, with ca. 14–18 pores (long axis: 6–10 μm) in posterior region. Branchiae eight pairs in holotype, 6–11 pairs in paratypes (beginning on chaetiger 4). Branchiae cylindro-conical with a rounded tip; dense ciliary bands present on middle line ( Figs 16A ; 19B, C ); shorter than segment width, first pair slightly shorter than second one, last pair of branchiae shorter than the others ( Figs 13A ; 15A ; 16A ); 159 μm long in anterior region, 177 μm long in middle region, 139 μm long in posterior region. Notopodial postchaetal lobes from chaetiger 1, short, cirriform, increasing in length to chaetiger 3 in pre- branchial region ( Figs 13A, B ; 14A ; 15C ); longer and finger-like in branchial region, but shorter, with an enlarged base and weakly jointed on last 2–3 branchial ( Figs 13A ; 14 A–C; 15D, E); short, triangular and weakly jointed in postbranchial region ( Figs 13C ; 14A, D, E ; 15 F–J); becoming longer and filiform, with weakly jointed base in preanal region ( Figs 14G ; 15 K–L). Neuropodial postchaetal lobes absent. Three types of chaetae: limbate, capillary and lyrate. Limbate chaetae hirsute, present on both notopodia of chaetigers 1–14 (chaetal length: 169-234 μm) and neuropodia (length: 167–270 μm). Notopodial and neuropodial capillary chaetae from chaetiger 15 to pygidium; 223–327 μm long in middle region; 225–278 μm long in posterior region. Lyrate chaetae from chaetiger 2 to end of branchial region, all of them of a single type (type I), with unequal branch lengths and equal branch thickness; num- bering 2–4 on anterior chaetigers, 41–54 μm long, bearing dense hairs on shaft and at conjunction between branches ( Figs 13B ; 19 A–C; 20A, B), long branch 2.5–3.5 times longer than short one, inner teeth discernible; numbering 1 in posterior chaetigers, 60–81 μm long, shaft without hairs long branch 4–4.5 times longer than short branch, inner teeth discernible ( Figs 13C ; 15G ; 20A, B, D ).

Notopodia of anterior region bearing 3–4 lyrate chaeta and 10–16 limbate chaetae; those of middle region bear- ing 4–10 capillary chaetae and 1–2 lyrate chaetae; those of posterior region bearing 6–8 capillary chaetae and one lyrate chaetae. Neuropodia of anterior region bearing 12–18 limbate chaetae; those of middle region bearing capil- lary 4-9 capillary chaetae; those of posterior region bearing 6–9 capillary chaetae. Pygidium rounded with three anal cirri; two dorso-lateral cirri (thin, digitiform, 35–38 μm long) and one mid-ventral cirrus (thick, 20 μm long); anal aperture on dorsal side, with dense cilia ( Figs 14G ; 15A , K–L; 16D).

Reproduction. Some specimens have eggs or sperm packages in their coelomic cavities. Eggs usually present from chaetiger 24 onwards; each segment carries 4– 5 eggs. The diameter of eggs varies between 32 and 140 μm. Sperm packages as white masses, from chaetiger 15 onwards. No specific coloration exists on or around the nuchal organs of the male and female individuals of the species.

Remarks. Paradoneis longifurcata n. sp. is mainly characterized by having long notopodial postchaetal lobes in the post-branchial region that are enlarged and weakly jointed basally; and a high ratio between the lengths of long and short branches of the lyrate chaetae.

The main morphological differences between P. longifurcata n. sp. and the other Paradoneis species are summarized in Table 1 . The morphology of Paradoneis longifurcata n.sp. coincides to some extent with those of P. lyra and P. forticirrata , but differs from them in the following characters. (1) The number of the prebranchial chaetigers is always three in P. longifurcata n. sp. and P. lyra , but 3–4 in P. forticirrata ; (2) The number of branchial pairs is lower (7–11 pairs) in P. longifurcata n. sp. in comparison with P. lyra (8–14 pairs) or with P. forticirrata (15–17 pairs); (3) Notopodial postchaetal lobes are finger-shaped with an enlarged, jointed base in P. longifurcata n.sp., but without an enlarged, jointed base in P. lyra and P. forticirrata ; (4) The maximum ratio between long and short TABLE 1 . List of all described Paradoneis species with selected diagnostic features. branches of lyrate chaetae is up to 4.5 in P. longifurcata n. sp. and up to 2–3 in P. lyra ; there is no information about P. forticirrata .

Habitat and Distribution. This species was found in soft substrata and in serpulid reefs at depths ranging from 15 to 100 m in the Sea of Marmara.

Etymology. This species name refers to the morphology of the lyrate chaeta that has one branch that is 4–4.5 times longer than the other one.

Figures

FIGURE 13. Paradoneis longifurcata n.sp. A, Line drawing of the holotype (ESFM-POL/2013-1100); B, Lyrate chaetae with hairs and postchaetal lobe from chaetiger 2 (ESFM-POL/2013-1391); C: Lyrate chaeta from a posterior chaetiger and weakly jointed lobe (ESFM-POL/2013-1391). Scale bars: A, 382 µm; B, 31 µm; C, 18 µm.

FIGURE 14. Paradoneis longifurcata n.sp. A, Antero-dorsal view of paratype (ESFM-POL/2013-1391); B, Cross-section from chaetiger 5 (ESFM-POL/2013-1391); C, Cross section from chaetiger 8 (ESFM-POL/2013-1391); D, Cross-section from chae- tiger 11 (ESFM-POL/2013-1391); E, Cross-section from chaetiger 26 (ESFM-POL/2013-1391); F, Cross-section of chaetiger 37 (ESFM-POL/2013-1391); G, Dorsal view of preanal chaetigers and pygidium (ESFM-POL/2013-1391). Scale bars: A, 164 µm; B, 122 µm; C, 131 µm; D, 203 µm; E, 112 µm; F, 141 µm; G, 145 µm.

FIGURE 15. Paradoneis longifurcata n.sp. A, Overview of holotype with tube (ESFM-POL/2013-1100); B, Detail of probos- cis (ESFM-POL/2013-1391); C, Antero-dorsal view of prostomium and first three chaetigers with notopodial postchaetal lobes (ESFM-POL/2013-1391); D, Lobes from chaetigers 8 and 9 (ESFM-POL/2013-1100); E, Last two chaetigers of branchial region with lobes (ESFM-POL/2013-1100); F, Weakly jointed lobe from posterior chaetigers with lyrate chaeta (ESFM-POL/2013- 1100); G, Lyrate chaeta from posterior chaetiger with weakly jointed lobe (ESFM-POL/2013-1100); H, Weakly jointed lobe from posterior chaetiger (ESFM-POL/2013-1100); I, Weakly jointed lobe from posterior chaetiger (ESFM-POL/2013-1100); J, Weakly jointed lobe from posterior chaetiger (ESFM-POL/2013-1100); K, Ventral view of pygidium (ESFM-POL/2013-1391); L, Latero-dorsal view of pygidium (ESFM-POL/2013-1100). Scale bars: A, 605 µm; B, 84 µm; C, 98 µm; D, 55 µm; E, 38 µm; F, 41 µm; G, 23 µm; H, 39 µm; I, 42 µm; J, 42 µm; K, 206 µm; L, 142 µm.

FIGURE 16. Paradoneis longifurcata n.sp. A, SEM of anterior region in lateral view (ESFM-POL/2013-1391); B, Detail of proboscis (ESFM-POL/2013-1391); C, Nuchal organ (ESFM-POL/2013-1391); D: Preanal region and pygidium in dorsal view (ESFM-POL/2013-1391). Scale bars: A, 228 µm; B, 78 µm; C, 5 µm; D, 102 µm.

FIGURE 17. Paradoneis longifurcata n.sp. A, Lateral view of prostomium (ESFM-POL/2013-1391); B, Lateral organ on peristomium (Enlargement from C); C: Nuchal and lateral organs.Abbreviations: lo, lateral organ; no, nuchal organ. Scale bars: A, 43 µm; B, 3 µm; C, 9 µm.

FIGURE 18. Paradoneis longifurcata n.sp. A, Dorsal view of prostomium (ESFM-POL/2013-1391); B, Ventral view of pro- stomium (ESFM-POL/2013-1391); C, Lateral view of prostomium (ESFM-POL/2013-1391). Abbreviations: dcb, dorsal ciliary band; ep, eversible palpode; lo, lateral organ; lso, lateral sense organ; nacb, nuchal associated ciliary band; no, nuchal organ; ntpcl, notopodial postchaetal lobe; tcb, transversal ciliary band. Scale bars: A, 72 µm; B, 114 µm; C, 28 µm.

FIGURE 19. Paradoneis longifurcata n.sp. A, Lyrate chaeta with hirsute shaft from chaetiger 2 (ESFM-POL/2013-1391); B, Lyrate chaetae with hirsute shaft from chaetiger 6 (ESFM-POL/2013-1391); C, Lyrate chaeta with hirsute shaft from chaetiger 10 (ESFM-POL/2013-1391). Abbreviations: bran, branchiae; lso, lateral sense organ; ntpcl, notopodial postchaetal lobe. Scale bars: A, 18 µm; B, 16 µm; C, 15 µm.

FIGURE 20. Paradoneis longifurcata n.sp. A, Notopodial postchaetal lobe with lyrate chaeta and lateral sense organ from pos- terior chaetigers (ESFM-POL/2013-1391); B, Notopodial postchaetal lobe with lyrate chaeta from posterior chaetigers (ESFM- POL/2013-1391); C, Notopodial postchaetal lobe (ESFM-POL/2013-1391); D, Notopodial postchaetal lobe with lyrate chaeta from posterior chaetigers (ESFM-POL/2013-1391). Abbreviations: lso, lateral sense organ; ntpcl, notopodial postchaetal lobe. Scale bars: A, 28 µm; B, 24 µm; C, 13 µm; D, 26 µm.

FIGURE 21. Paradoneis longifurcata n.sp. A, Parapodium on chaetiger 1 (ESFM-POL/2013-1391); B, Parapodium from posterior branchial region (ESFM-POL/2013-1391); C, Parapodium from posterior region (ESFM-POL/2013-1391).Abbrevia- tions: lso, lateral sense organ; neu, neuropodium; not, notopodium; ntpcl, notopodial postchaetal lobe. Scale bars: A, 16 µm; B, 18 µm; C, 25 µm.