Paraonis lobulata, Çinar & Dağli & Erdoğan-Dereli, 2022

Çinar, Melih Ertan, Dağli, Ertan & Erdoğan-Dereli, Deniz, 2022, The diversity of polychaetes (Annelida: Polychaeta) in a longterm pollution monitoring study from the Levantine coast of Turkey (Eastern Mediterranean), with the descriptions of four species new to science and two species new to the Mediterranean fauna, Journal of Natural History 56 (33 - 36), pp. 1383-1426 : 1407-1413

Paraonis lobulata sp. nov.

( Figures 11–14 )

Type material

Levantine Sea, Turkey, holotype. ESFM-POL/2019-11 , 02 September 2019, ERDSWR, 36.588717°N, 34.321083°E, 37 m, pebbles with mud .

Paratypes. ESFM-POL/2019-12 , 02 September 2019, ERDSWR, 36.588717°N, 34.321083°E, 37 m, pebbles with mud, 12 specimens; ESFM-POL/2019- 15 , 02 September 2019, TASSW1 , 36.265567°N, 33.87875°’E, 37 m, muddy sand with shell fragments, 5 specimens; ESFMPOL/2019-16, 04 September 2019, SAMSWR, 36.04845°N, 35.940767°E, 67 m, maerl bed, 19 specimens; ESFM-POL/2019-17 , 02 September 2019, GRESW2 , 36.27875°N, 34.0498°E, 25 m, mud, 4 specimens .

Non-type material

Levantine Sea, Turkey. ESFM-POL/2017-158 , 01 August 2017, Adrasan Bay , 36.33507°N, 30.52909°E, 81 m, sandy mud with shell fragments, 1 specimen; ESFM-POL/2019-22 , 07 September 2019, off Samandağ, 36.392564°N, 35.8033°E, 67 m, mud with maerl, 9 specimens; ESFM-POL/2019-21 , 25 July 2019, off Taşucu, 36.233553°N, 33.894669°E, 25 m, muddy sand with shell fragments, 2 specimens; ESFM-POL/2019-19 , 27 July 2019, off Göksu River , 36.421086°N, 34.126275°E, 60 m, mud, 5 specimens; ESFM-POL/2019-18 , 06 September 2019, off Göksu River , 36.421086°N, 34.126275°E, 60 m, mud, 21 specimens; ESFM-POL/2019-13 , 09 May 2019, off Erdemli, 36.671833°N, 34.555558°E, 55 m, mud, 6 specimens; ESFM-POL/2019-20 , 06 September 2019, off Erdemli, 36.671833°N, 34.555558° E, 55 m, mud, 16 specimens; ESFM-POL/2019-14 , 26 July 2019, off Samandağ, 36.392564° N, 35.8033°E, 60 m, maerl bed, 2 specimens; Aegean Sea, Turkey . ESFM-POL/2016-199 , 25 November 2016, off Çeşme-Ildırı, 38.408192°N, 26.388078°E, 60 m, mud, 2 specimens; ESFM-POL/2017-157 , 27 July 2017, off Ayvalık, Çıplak Ada Island , 39.30054°N, 26.56244°E, 35 m, sandy mud with Caulerpa cylindracea , 1 specimen; ESFM-POL/2018-124 , 31 August 2018, off Dikili, 39.076483°N, 26.858533°E, 30 m, mud, 1 specimen .

Description

Holotype complete, 0.83 mm long (2.3–9.7 mm long in paratypes), 0.24 mm wide at chaetiger 10 (0.19–0.25 mm wide in paratypes), with 70 chaetigers (25–98 chaetigers in paratypes). Colour of holotype in alcohol yellowish to light brown with brown speckles along body, in most paratypes with distinct brown speckles/spots all around body ( Figure 12 (d,j,k)). Body cylindrical, thin; widths of prebranchial and branchial regions nearly same; getting stout and lobate on posterior chaetigers; getting thinner on pre-anal chaetigers ( Figures 11 (a–c), 12(a,i)). A pair of skin folds, starting at chaetiger 5, present at both dorsolateral sides of chaetigers in branchial region ( Figure 13 (a)). A dense dorsal ciliary band (dcb) present on mid-dorsal transversal line of each prebranchial and branchial chaetigers ( Figure 13 (a)). Ciliary bands absent on ventral side of body.

Prostomium subtriangular; much longer than wide (length/width: 1.05); anterior part rounded; eversible palpode with cilia on anterior margin of prostomium ( Figure 13 (a,d,f)); eyes absent in all specimens. Cheek organ located on lateral sides of prostomium, retractable, without cilia ( Figures 12 (e), 13(b,c)). One complete ciliated band, known as the nuchal associated ciliary band, ventrally connecting one nuchal organ to another, except for a gap in dorsal side. A long, dense transversal ciliary band present on dorsal side of prostomium, more or less in M-shaped ( Figures 12 (d), 13(c–f)). A pair of nuchal organs as narrow, deep, long and slanted slits, placed on dorso-lateral sides of posterior prostomium, more or less convex in shape; with dense internal ciliation; cilia reaching outer margin of slits; associated with ciliary band and nuchal associated ciliary band ( Figure 13 (d–f)); without pigmentation in holotype, brown speckles/spots in some paratypes. Peristomium discernable on dorsal side, partly fused with posterior margin of prostomium ( Figure 13 (a,c,d,f)).

Proboscis unlobed with dense cilia. Mouth with five buccal lips, two placed anteriorly, two placed laterally and one placed posteriorly; posterior one large, bilobed, extending to anterior margin of chaetiger 1 ( Figure 12 (b,g)).

Branchiae numbering 11 pairs in holotype, 11–15 pairs in paratypes, beginning on chaetiger 4 in all specimens; flattened, more or less lanceolate with a rounded tip; a dense ciliary band on both sides of branchiae; branchial length usually shorter than segment width, getting longer posteriorly, not elongated ( Figures 11 (a,b), 12(a,k)); 184 μm long in anterior region, 200 μm long in middle region, 148 μm long in posterior region; branchial length/width ratio between 3.1 and 4.6.

Interramal lobes absent. Ventral lobes present between chaetigers 3 and 14, as a rudimentary ridge; getting large, bulbous, bilobed on both sides of chaetiger after chaetiger 14 ( Figure 12 (b,c)). Notopodial papilla present between chaetigers 8 and 14 (7–17 in paratypes), small, ovoid ( Figures 12 (h,k), 14(a)). Notopodial postchaetal lobes present; short, cirriform in first chaetiger; short, digitiform in second chaetiger; stout, long, finger-like, digitiform with suddenly tapering pointed tip after chaetiger 3 along branchial region; stout, long, finger-like with elongated pointed tip in posterior region ( Figures 11 (a, b), 12(i–k), 13(a), 14(a,b,f)). Neuropodial postchaetal lobes absent.

Lateral sense organs present between notopodia and neuropodia on all chaetigers, placed just posterior to notopodial postchaetal lobes; with flexible ciliae distinctly protruding from opening or embedded into pore. Irregular, elliptical clustered sensory pores present along dorsal and ventral surfaces of body ( Figure 14 (c–e)); with ca. 13–15 pores (long axis of organ: ca. 6.8–7 μm) in prebranchial region, with ca. 10–12 pores (long axis of organ: 5.7–6 μm) in branchial region, with ca. 8–9 pores (long axis of organ: 2.5–3 μm) in posterior region.

Two types of chaetae present on chaetigers; capillary and modified neurochaetae. Capillary chaetae beginning on noto- and neuropodia of chaetiger 1, present on noto-and neuropodia of all subsequent chaetigers. Capillary chaetae numbering 12–20 in each anterior notopodium, arranged in three rows, ca. 180 μm long; numbering 8–16 in each anterior neuropodium, arranged in three rows, ca. 185 μm long; numbering 5–8 in each middle notopodium, arranged in one row, ca. 230 μm long; numbering 5–8 in each middle neuropodium, arranged in one row, ca. 280 μm long; numbering 3–4 in each posterior notopodium, arranged in one row, ca. 270 μm long; numbering 5–7 in each posterior neuropodium, arranged in one row, ca. 340 μm long.

Modified neuropodial chaetae of Strelzovia type, with two forms (long and short), starting from chaetiger 37 (25–40 in paratypes) to posterior end, numbering two (both type) in each neuropodium until pre-anal region, numbering one (only type 1) in pre-anal region accompanied by capillary chaetae, brownish colour in most specimens; superior ones longer; first form of Strelzovia-type chaeta, very long (average length: 136 μm), becoming gradually thinner but not hirsute on convex side; second form of Strelzoviatype chaeta, short (average length: 87 μm), more or less sigmoid in shape, getting abruptly thinner without fibrils on convex side ( Figures 11 (c), 12(f), 14(f,g)).

Pygidium rounded with three anal cirri; two cirri very long, filiform, placed on laterodorsal side; one cirrus dull, long and located mid-ventrally; anal aperture on dorsal side ( Figure 14 (b)).

Remarks

Paraonis lobulata sp. nov. is mainly characterised by having long and clavate notopodial postchaetal lobes, cirriform notopodial papillae and bilobed posterior lip. The species most morphologically similar to Paraonis bilobulata sp. nov. are P. pygoenigmatica Jones, 1968 , P. fulgens (Levinsen, 1884) , P. paucibranchiata Cerruti, 1909 and P. strelzovi Hartmann-Schröder, 1980 . However, P. lobulata sp. nov. differs from these species in terms of the following characters: (1) the morphology of the notopodial postchaetal lobes in the branchial region (large, digitiform, with abruptly tapering tip, almost half the length of branchiae in P. lobulata sp. nov. vs cirriform and 5.5 times shorter than branchiae in P. pygoenigmatica ; digitiform, long and thin, with weakly asymmetrical enlargement on the base, 3 times shorter than branchiae in P.fulgens ; stout, 4 times shorter than branchiae in P. paucibranchiata ; long, finger-like, 2–2.5 times shorter than branchiae in P. strelzovi ); (2) the presence of the notopodial papillae (present in P. lobulota sp. nov. vs absent in P. fulgens and P. pygoenigmatica ; unknown/not documented in P. paucibranchiata and P. strelzovi ); (3) the number of branchiae (11–15 pairs in P. lobulata sp. nov. vs 25 pairs in P. fulgens , 15–19 pairs in P. pygoenigmatica , four pairs in P. paucibranchiata and three pairs in P. strelzovi ); (4) the morphology of the modified neurochaeta [long and tapering gradually (the Strelzovia type) in P. lobulata sp. nov. vs short and curved, with a strong hood (the Acmira type) in P. fulgens , P. paucibranchiata and P. strelzovi ; the toothed type in P. pygoenigmatica ].

In the most paraonids, the posterior buccal lip on the mouth consists of rounded longitudinal folds, extending back to the anterior margin of the chaetiger 1 or 2 (ErdoğanDereli and Çinar 2019, 2020a, 2020b, 2021). However, the posterior buccal lip of Paraonis lobulata sp. nov. is enlarged and distinctly bilobed ( Figure 12 (b,g)). This kind of posterior lip has not been reported in paraonids before.

Reproduction

Some specimens of Paraonis lobulata sp. nov. collected in May had sperm (as white masses) within chaetigers from 40–59 to the end of the body.

Distribution

This species was found in soft substrata between 25 and 81 m depths in the Levantine and Aegean Seas, Turkey, eastern Mediterranean.

Etymology

The epithet lobulata was selected due to morphological shape of the segments and the posterior buccal lip.

Figures

Figure 11. Paraonis lobulata sp. nov. holotype (ESFM-POL/2019-11): (a) general view of body, dorsal view; (b) antero-dorsal view of body; (c) modified neurochaetae on chaetigers 49 and 50. Scale bar: a = 193 µm; b = 180 µm; c = 51 µm.

Figure 12. Paraonis lobulata sp. nov. holotype, paratype and non-type specimens: (a) antero-dorsal view of body, arrows pointing to lobated shapes of segments, paratype (ESFM-POL/2019-12); (b) antero-ventral view of body (ESFM-POL/2019-12); (c) ventral view of body, branchial region (ESFM- POL/2019-12); (d) dorsal view of prostomium (ESFM-POL/2018-124); (e) lateral margin of prostomium, dorsal side (ESFM-POL/2018-124); (f) modified neurochaetae on chaetiger 63 (ESFM-POL/2019-11); (g) bilobated posterior lip (ESFM-POL/2019-12); (h) notopodial papilla on chaetiger 12 (ESFM-POL/2017- 157); (i) lateral view of branchial region, unlabeled arrow pointing to lobe-shaped segment (ESFM- POL/2019-12); (j) posterior body region, unlabeled arrow pointing to lobe-shaped segment (ESFM- POL/2019-11); (k) dorsal view of chaetiger 12, with branchia and notopodial papilla (ESFM-POL/2017- 157). Scale bar: a = 121 µm; b = 96 µm; c = 155 µm; d = 71 µm; e = 71 µm; f = 44 µm; g = 74 µm; h = 16 µm; i = 30 µm; j = 255 µm; k = 130 µm. Abbreviations. bran: branchia; cb: ciliary band; co: cheek organ; no: nuchal organ; np: notopodial papilla; ntpcl: notopodial postchaetal lobe; per: peristomium; vl: ventral lobe.

Figure 13. Paraonis lobulata sp. nov. paratype and non-type specimens:(a) antero-dorsal view of body (ESFM-POL/2018-124); (b) cheek organ (ESFM-POL/2018-124); (c) dorso-lateral view of prostomium and peristomium (ESFM-POL/2018-124); (d) Lateral view of prostomium and peristomium (ESFM-POL/ 2019-14); (e) dorso-lateral view of prostomium (ESFM-POL/2017-157); (f) dorsal view of prostomium (ESFM-POL/2017-157). Scale bar: a = 154 µm; b = 9 µm; c = 62 µm; d = 46 µm; e = 34 µm; f = 81 µm. Abbreviations. bran: branchia; cb: ciliary band; co: cheek organ; dcb: dorsal ciliary band; lso: lateral sense organ; nacb: nuchal organ associated ciliary band; no: nuchal organ; np: notopodial papilla; ntpcl: notopodial postchaetal lobe; per: peristomium; sf: skin fold.

Figure 14. Paraonis lobulata sp. nov. paratype and non-type specimens: (a) dorsal view of notopodia, branchial region (ESFM-POL/2018-124); (b) posterior end with pygidium, dorsal side (ESFM-POL/2017- 157); (c) lateral sense organ, branchial region (ESFM-POL/2017-157); (d) lateral sense organ, postbranchial region (ESFM-POL/2017-157); (e) lateral sense organ, posterior region (ESFM-POL/2019-14); (f) notopodium, posterior region (ESFM-POL/2019-14); (g) parapodium with modifed neurochaetae, posterior region. Scale bar: a = 44 µm; b = 82 µm; c = 11 µm; d = 6 µm; e = 0.2 µm; f = 20 µm. Abbreviations. ac: anal cirri; lso: lateral sense organ; mneu: modified neurochaeta; np: notopodial papilla; ntpcl: notopodial postchaetal lobe.