Paradoneis heterochaeta, 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 : 470-481

Paradoneis heterochaeta n. sp.

urn:lsid:zoobank.org:act:42661073-8BD9-4DF6-B1A7-28A41CC6F261

Material examined. Holotype, ESFM-POL/2013-1060 , 08 June 2013, station Y15, 40°19’11’’N, 27°33’51’’E, 10 m, sandy mud.

Paratypes. 224 specimens: ESFM-POL/2013-1361 , 07 June 2013, station Y7, 40°24’28’’N, 26°51’24’’E, 25 m, maerl bed, 29 specimens ; ESFM-POL/2013-1078 , 07 June 2013, station Y10, 40°31’28’’N, 26°54’12’’E, 10 m, sand, 28 specimens ; ESFM-POL/2013-1082 , 10 June 2013, station Y13, 40°45’00’’N, 27°20’29’’E, 25 m, muddy sand with shell fragments, 97 specimens ; ESFM-POL/2013-1088 , 11 June 2013, station Y18, 40°58’01’’N, 27°31’26’’E, 10 m, mud with pebble, 70 specimens.

Additional material: 1022 specimens: ESFM-POL/2013-57 , 06 June 2013, station Y2, 40°06’32’’N, 26°22’31’’E, 25 m, mud with pebble, 2 specimens ; ESFM-POL/2013-72 , 06 June 2013, station Y3, 40°12’15’’N, 26°26’12’’E, 25 m, mud, 5 specimens ; ESFM-POL/2013-75 , 06 June 2013, station Y3, 40°13’10’’N, 26°25’45’’E, 50 m, sand, 3 specimens ; ESFM-POL/2013-67 , 06 June 2013, station Y3, 40°12’052’’N, 26°26’350’’E, 10 m, mud with shell fragments, 1 specimen ; ESFM-POL/2013-1062 , 07 June 2013, station Y4, 40°17’36’’N, 26°35’51’’E, 10 m, mud, 1 specimen ; ESFM-POL/2013-83 , 07 June 2013, station Y4, 40°17’49’’N, 26°35’44’’E, 25 m, maerl bed, 11 specimens ; ESFM-POL/2013-1065 , 07 June 2013, station Y4, 40°18’09’’N, 26°35’15’’E, 50 m, sand, 2 specimens ; ESFM-POL/2013-91 , 07 June 2013, station Y5, 40°20’55’’N, 26°40’38’’E, 25 m, mud, 11 specimens ; ESFM-POL/2013-99 , 07 June 2013, station Y6, 40°26’03’’N, 26°41’59’’E, 25 m, mud, 10 specimens ; ESFM- POL/2013-101, 07 June 2013, station Y6, 40°25’23’’N, 26°44’03’’E, 50 m, mud with Amphiura filiformis , 2 specimens ; ESFM-POL/2013-1069 , 07 June 2013, station Y8, 40°25’15’’N, 27°03’49’’E, 10 m, mud, 1 specimen ; ESFM-POL/2013-1363 , 08 June 2013, station Y9, 40°26’20’’N, 27°11’32’’E, 10 m, mud with gravel and shell fragments, 1 specimen ; ESFM-POL/2013-1422 , 08 June 2013, station Y9, 40°26’25’’N, 27°11’29’’E, 25 m, mud, 1 specimen ; ESFM-POL/2013-1365 , 08 June 2013, station Y9, 40°28’09’’N, 27°11’14’’E, 50 m, mud, 2 specimens ; ESFM-POL/2013-1366 , 07 June 2013, station Y10, 40°30’38’’N, 26°54’58’’E, 25 m, maerl bed, 4 specimens ; ESFM-POL/2013-1368 , 08 June 2013, station Y11, 40°36’12’’N, 27°05’20’’E, 10 m, mud, 1 specimen ; ESFM- POL/2013-1369, 08 June 2013, station Y11, 40°35’55’’N, 27°05’25’’E, 25 m, mud with Turritella communis , 1 specimen ; ESFM-POL/2013-1370 , 08 June 2013, station Y11, 40°34’50’’N, 27°05’59’’E, 50 m, mud, 1 specimen ; ESFM-POL/2013-1371 , 08 June 2013, station Y12, 40°40’38’’N, 27°16’25’’E, 10 m, sand, 1 specimen ; ESFM- POL/2013-1372, 08 June 2013, station Y12, 40°40’23’’N, 27°16’31’’E, 25 m, mud, 1 specimen ; ESFM-POL/2013- 1080 , 10 June 2013, station Y13, 40°44’59’’N, 27°20’16’’E, 10 m, muddy sand with shell fragments, 4 specimens ; ESFM-POL/2013-1084 , 08 June 2013, station Y15, 40°19’11’’N, 27°33’51’’E, 10 m, sandy mud, 42 specimens ; ESFM-POL/2013-1373 , 08 June 2013, station Y15, 40°25’41’’N, 27°27’57’’E, 50 m, mud, 1 specimen ; ESFM- POL/2013-1374, 09 June 2013, station Y16, 40°24’13’’N, 27°39’47’’E, 41 m, mud, 1 specimen ; ESFM-POL/2013- 1375 , 09 June 2013, station Y17, 40°39’58’’N, 27°41’08’’E, 50 m, mud, 7 specimens ; ESFM-POL/2013-1378 , 09 June 2013, station Y17, 40°41’03’’N, 27°39’52’’E, 100 m, mud, 1 specimen ; ESFM-POL/2013-1379 , 10 June 2013, station Y18, 40°54’28’’N, 27°33’24’’E, 25 m, maerl bed, 16 specimens ; ESFM-POL/2013-1087 , 12 June 2013, station Y19, 40°59’52’’N, 27°41’59’’E, 10 m, maerl bed, 10 specimens ; ESFM-POL/2013-1091 , 12 June 2013, station Y19, 40°58’36’’N, 27°42’29’’E, 25 m, maerl bed, 125 specimens ; ESFM-POL/2013-1385 , 16 June 2013, station Y22, 40°23’22’’N, 27°59’46’’E, 50 m, mud, 11 specimens ; ESFM-POL/2013-1095 , 13 June 2013, station Y24, 41°03’55’’N, 28°09’12’’E, 10 m, sandy mud with shell fragments, 1 specimen ; ESFM-POL/2013-1386 , 15 June 2013, station Y24, 41°03’08’’N, 28°08’44’’E, 25 m, maerl bed, 154 specimens ; ESFM-POL/2013-1389 , 16 June 2013, station Y24, 41°00’16’’N, 28°07’50’’E, 50 m, muddy sand with shell fragment, 13 specimens ; ESFM- POL/2013-1395, 16 June 2013, station Y25, 40°24’48’’N, 28°20’41’’E, 25 m, sandy mud with Amphiura filiformis , 2 specimens ; ESFM-POL/2013-1397 , 16 June 2013, station Y26, 40°22’36’’N, 28°39’41’’E, 25 m, muddy sand with shell fragments, 20 specimens ; ESFM-POL/2013-1398 , 17 June 2013, station Y28, 40°29’54’’N, 28°51’29’’E, 25 m, mud, 81 specimens ; ESFM-POL/2013-1405 , 17 June 2013, station Y29, 40°34’01’’N, 28°44’45’’E, 200 m, muddy sand with shell fragments, 1 specimen ; ESFM-POL/2013-1400 , 17 June 2013, station Y29, 4032’34’’N, 2846’53’’E, 25 m, maerl bed, 2 specimens ; ESFM-POL/2013-1423 , 17 June 2013, station Y29, 40°32’39’’N, 28°46’42’’E, 50 m, muddy sand, 20 specimens ; ESFM-POL/2013-1402 , 17 June 2013, station Y29, 40°33’32’’N, 28°44’58’’E, 100 m, muddy sand, 29 specimens ; ESFM-POL/2013-1098 , 14 June 2013, station Y31, 40°01’44’’N, 28°26’31’’E, 10 m, sand, 2 specimens ; ESFM-POL/2013-1406 , 14 June 2013, station Y31, 41°01’25’’N, 28°26’23’’E, 25 m, maerl bed, 210 specimens ; ESFM-POL/2013-1409 , 24 June 2013, station Y34, 40°56’58’’N, 28°51’39’’E, 25 m, sandy mud with shell fragments, 56 specimens . ESFM-POL/2013-1412 , 22 June 2013, station Y36, 40°57’57’’N, 29°01’14’’E, 10 m, mud, 1 specimen ; ESFM-POL/2013-1413 , 19 June 2013, station Y38, 40°47’42’’N, 29°18’22’’E, 50 m, muddy sand, 9 specimens ; ESFM-POL/2013-1415 , 19 June 2013, station Y39, 40°39’36’’N, 29°09’18’’E, 10 m, sandy mud, 1 specimen ; ESFM-POL/2013-1416 , 19 June 2013, station Y40, 40°41’22’’N, 29°20’58’’E, 10 m, mudy sand, 61 specimens ; ESFM-POL/2013-1417 , 20 June 2013, station Y41, 40°41’52’’N, 29°25’08’’E, 25 m, mud with shell fragments, 7 specimens ; ESFM-POL/2013-1419 , 20 June 2013, station Y42, 40°45’43’’N, 29°29’39’’E, 50 m, mud, 71 specimens .

Description. Holotype complete, 15 mm long (5.37–17.16 mm long in paratypes), 0.47 mm wide (0.20–0.55 mm wide in paratypes) with 84 chaetigers (53–100 chaetigers in paratypes). Color in alcohol pale brownish in large specimens (pale yellowish in small ones), with dark brown speckles scattered along body ( Fig. 6 A–D). Body stout, somewhat cylindrical; widths of prebranchial and branchial regions nearly same; body significantly thicker at beginning of postbranchial region; gradually thinner towards posterior end ( Figs 4A ; 5A ; 6A, B ; 7A ). A dense cili- ary band on mid-dorsal transversal line of each prebranchial and branchial chaetigers ( Figs 7A, B ; 10A, B ); ciliary bands absent from ventral side ( Fig. 8A ). Prostomium triangular; longer than wide (length/width: 1.2), anterior part somewhat or distinctly conical, with an eversible palpode without pores ( Figs 5A ; 6B, C ; 7A ; 8B ); eyes present. Lat- eral organs not observed on prostomium and peristomium. 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. 9 A–D). Peristomium highly reduced on dorsal view ( Figs 6B, C ; 8B ; 9A, C ). A pair of nuchal organ as deep, broad slits placed dorso-laterally on posterior part of prostomium; cilia in nuchal organ well extending out of margin of slits; dense brown pigment present on each side of nuchal organ in many paratypes ( Figs 6B, C ; 8B, C ). Mouth with eight buccal lips; two placed anteriorly; six lips placed posterior part, extending to anterior margin of chaetiger 2 ( Figs 8A ; 9B ). Proboscis without lobes, with dense cilia ( Fig. 8A ). Branchiae numbering 12 pairs in holotype, 8 12 pairs in paratypes, beginning on chaetiger 4 in all specimens; flattened, thin, cylindro-conically shaped, with a rounded tip; dense ciliary bands on both side on outer margin of branchiae ( Fig. 7B ); shorter than segment width, first and last pair of branchiae shorter than others ( Figs 4A ; 7A, B ); 164 μm long in anterior region, 231 μm long in middle region, 125 μm long in posterior region. Notopodial postchaetal lobes short, thick, cirriform on chaetigers 1 and 2; longer and much more stouter than others on chaetiger 3 ( Figs 5A ; 10A ); short, digitiform on branchial region ( Figs 5A, B ; 7B ; 10B ); very short, triangular with irregular dense pores on posterior region ( Figs 5C ; 6F ; 10C ; 12A, C ); longer, thin, filiform on pre-anal region ( Figs 4A, F ; 6D ; 10D ). Neuropodial postchaetal lobes absent ( Figs 5B, C ; 8A ). Lateral sense organs located between notopodium and neuropodium, below notopodial postchaetal lobes in each chaetiger ( Figs 9C ; 12 A–C); with flexible cilia distinctly protruding from opening or embedded into pore; one cilia present in each pore ( Fig. 10 C ; 12B, C ), showing its retractable character; lateral sense organs starting from chaetiger 1 to end of body; oval shaped with irregularly clustered pores; with ca. 10 pores in prebranchial region (long axis: ca. 10 μm), with ca. 20–22 pores (long axis: 7–10 μm) in branchial region, with ca. 17–28 pores (long axis: 8 μm) in posterior region. Five types of chaeta present on chaetigers; limbate, capillary and two types of lyrate chaetae. Limbate chaetae hirsute ( Figs 4C , 6E ), present both on notopodia (only on chaetigers 1–13) and neuropodia (pres- ent on chaetigers from 1 to pygidium), 228 μm long in anterior region, 412 μm long in middle region, 333 μm long in posterior region. Notopodial capillary chaetae starting from chaetiger 15 to pygidium; 218 μm long in middle region; 196 μm long in posterior region. Lyrate chaeta with unequal branches, long and short branches; two types based on thickness of branches; thickness of two branches equal (Type I) and thickness of two branches unequal (short branch thicker than long one) (Type II). Type I present from chaetiger 2 to pygidium, those on prebranchial and branchial chaetigers with dense hairs on one side of shaft, numbering 2–4, 68 μm long, long branch 1.5-2 times longer than short branch ( Figs 4B ; 11 A–C); chaetae in postbranchial region numbering 1–2, 40 μm long, long branch 1.5 times longer than short branch, teeth discernible, without hair ( Figs 4D ; 11D ). Type II lyrate chaeta pres- ent from chaetiger 19 to pygidium; numbering 1–3 on posterior chaetigers, 38 μm long; long branch 2–2.5 times longer than short branch; teeth discernible ( Fig. 4E , 11D ). Notopodia of anterior region bearing 2– 4 type I lyrate chaeta and 22–34 limbate chaetae; those of middle region bearing 9–16 capillary chaetae and 2–4 lyrate chaetae (type I and II); those of posterior region bearing 4–7 capillary chaetae and 2–4 lyrate chaetae (type I and II). Neuro- podia of anterior region bearing 20–30 limbate chaeta; neuropodia of middle region bearing 12–24 limbate chaeta; neuropodia of posterior region bearing 11–16 limbate chaetae. Pygidium rounded with three anal cirri; two cirri placed dorso-laterally (thin, digitiform, 45–48 μm long), one cirrus placed mid-ventrally (thick, 47 μm long); anal aperture on dorsal side, with dense cilia ( Figs 4A, F ; 6D ; 10D ).

Reproduction. Some specimens had eggs or sperm packages in their coelomic cavities. Eggs usually appeared from chaetiger 30 onwards; each segment carried 4– 6 eggs. The diameter of eggs varied between 77 and 96 μm. Sperm packages started from chaetiger 31 onwards; each segment carried two sperm packages. The female speci- mens did not have any pigmentation around the nuchal organs, while the male specimens had dense brownish pig- mentation near the nuchal organs ( Fig. 6C ). It seems that this species could be sexually dimorphic.

Remarks. Paradoneis heterochaeta n. sp. is mainly characterized by having dark brownish speckles irregularly scattered along the body; anterior part of prostomium distinctly conical; large-sized body (especially after the bran- chial region); very short notopodial postchaetal lobes (especially getting indistinct in post-branchial region, except for the preanal region) onwards); neuropodial limbate chaetae along the body; and two types of lyrate chaetae based on the thickness of the branches.

The main morphological differences between P. heterochaeta n. sp. and the other Paradoneis species are summarized in Table 1 . Paradoneis heterochaeta n. sp. is most similar to P. ilvana and P. brunnea . However, P. heterochaeta n. sp. differs from them in terms of the following characters: (1) Lyrate chaetae are of two types (type I, thickness of branches equal; type II, thickness of branches unequal) in P. heterochaeta n. sp. and P. ilvana , but P. brunnea only has one type (type I). However, both types of lyrate chaetae (types I and II) are simultaneously present in the postbranchial region of P. heterochaeta , whereas in the postbranchial region of P. ilvana only type II of lyrate chaeta occurs. (2) P. heterochaeta n. sp. has a large body size (especially after the branchial region) and dark brown speckles irregularly scattered along the body. On the other side, P. brunnea has a shorter body size and dark brown pigments densely covering the anterior part of the prostomium, and P. ilvana has longer but thinner body lacking pigmentation. (3) Prostomium triangular, with the anterior end distinctly conical in P. heterochaeta n. sp., but conical in P. brunnea and triangular with the anterior end weakly conical in P. ilvana . (4) The notopodial postchaetal lobes are short and cirriform in the prebranchial region, indistinctly digitiform in the branchial region, short and triangular in the postbranchial region of P. heterochaeta n. sp. In P. brunnea , they are small and oval in the prebranchial region, longer and finger-shaped in the branchial region, and finger-shaped or spindle-shaped in the postbranchial region. In P. ilvana , they are short and rounded in the prebranchial region, rudimentary in the branchial region and long and triangular in the postbranchial region.

Habitat and Distribution. This species was found on maerl beds and sandy-muddy bottoms at 10–200 m depths in the Sea of Marmara.

Etymology. This species name refers to the character of possessing two types of lyrate chaetae.

Figures

FIGURE 4. Paradoneis heterochaeta n.sp. A, line drawing of holotype (ESFM-POL/2013-1060); B, Lyrate chaeta from pre- branchial chaetigers (ESFM-POL/2013-1078); C, Limbate chaeta (ESFM-POL/2013-1082); D, Lyrate chaeta (thickness of branches equal) from posterior chaetigers (ESFM-POL/2013-1084); E, Lyrate chaeta from posterior chaetigers (thickness of branches unequal) (ESFM-POL/2013-1078); F, Pygidium. Scale bars: A, 955 µm; B, 11 µm; C, 30 µm; D, 13 µm; E, 15 µm; F, 92 µm.

FIGURE 5. Paradoneis heterochaeta n.sp. A, Line drawing of antero-dorsal region of paratype (ESFM-POL/2013-57); B, Cross-section of chaetiger 4 (ESFM-POL/2013-1082); C, Cross-section of chaetiger 40 (ESFM-POL/2013-1082). Scale bars: A, 330 µm; B, 135 µm; C, 154 µm.

FIGURE 6. Paradoneis heterochaeta n.sp. A, Complete paratype (ESFM-POL/2013-57); B, Antero-dorsal view (ESFM- POL/2013-57); C, Dorsal view of prostomium of male and female specimens (ESFM-POL/2013-1084); D, Pygidium (ESFM- POL/2013-57); E, Limbate chaetae from notopodium of a posterior chaetiger (ESFM-POL/2013-1082); F, Lyrate chaetae from a posterior chaetiger (ESFM-POL/2013-1082). Scale bars: A, 600 µm; B, 330 µm; C, 202 µm; D, 62 µm; E, 31 µm; F, 27 µm.

FIGURE 7. Paradoneis heterochaeta n.sp. A, SEM of antero-dorsal region of the body (ESFM-POL/2013-1084); B, Dorsal view of branchial region (ESFM-POL/2013-1084), arrows point to notopodial postchaetal lobes. Scale bars: A, 250 µm; B, 100 µm.

FIGURE 8. Paradoneis heterochaeta n.sp. A, Antero-ventral view of body with proboscis partly everted (ESFM-POL/2013- 1084); B, Dorsal view of prostomium and first chaetiger (ESFM-POL/2013-1084); C, Nuchal organ (ESFM-POL/2013-1084). Abbreviations: ep, eversible palpode; cno, cilia of nuchal organ; pro, prostomium; per, peristomium; prob, proboscis; lso, lateral sense organ. Scale bars: A, 209 µm; B, 119 µm; C, 11 µm.

FIGURE 9. Paradoneis heterochaeta n.sp. A, Dorsal view of prostomium (ESFM-POL/2013-1084) showing nacb from one side; B, Antero-lateral view of prostomium with proboscis (ESFM-POL/2013-1084); C, Lateral view of prostomium (ESFM- POL/2013-1084); D, Nuchal organ.Abbreviations: al, anterior lips; nacb, nuchal associated ciliary band; ntpcl, notopodial post- chaetal lobe; pro, prostomium; per, peristomium; prob, proboscis; lso, lateral sense organ; dcb, dorsal ciliary band; no, nuchal organ. Scale bars: A, 212 µm, B, 217 µm; C, 330 µm; D, 90 µm.

FIGURE 10. Paradoneis heterochaeta n.sp. A, Dorsal view of prostomium and first three chaetigers (ESFM-POL/2013-1084), with notopodial postchaetal lobes; B, Middle of branchial region (ESFM-POL/2013-1084); C, Lobe and lateral sense organ (from posterior chaetigers) (ESFM-POL/2013-1084); D, Preanal chaetigers and pygidium (ESFM-POL/2013-1084). Abbrevia- tions: bran, branchiae; dcb, dorsal ciliary band; ntpcl, notopodial postchaetal lobe; lso, lateral sense organ; aap, anal aperture; pyg, pygidium. Scale bars: A, 86 µm; B, 87 µm; C, 24 µm; D, 110 µm.

FIGURE 11. Paradoneis heterochaeta n.sp. A, Lyrate chaeta (type I) from chaetiger 2 (ESFM-POL/2013-1366); B, Lyrate chaetae (type I) from chaetiger 4 (ESFM-POL/2013-1366); C, Lyrate chaetae (type I) from chaetiger 13 (ESFM-POL/2013- 1366); D, Notopodium with lyrate chaetae (type II and III), postchaetal lobe and lateral sense organ (ESFM-POL/2013-1366). Abbreviation: lso, lateral sense organ. Scale bars: A, 6 µm; B, 9.5 µm; C, 24.5 µm; D, 18 µm.

FIGURE 12. Paradoneis heterochaeta n. sp. A, General view of a parapodium from posterior region (ESFM-POL/2013-1366); B, Lateral sense organ from a posterior chaetiger (ESFM-POL/2013-1366); C, Notopodium from posterior chaetigers with a lat- eral sense organ and notopodial postchaetal lobe (ESFM-POL/2013-1366).Abbreviations: neu, neuropodium; not, notopodium; ntpcl, notopodial postchaetal lobe; lso, lateral sense organ. Scale bars: A, 23 µm; B, 2 µm; C, 6 µm.