Scolelepis (S.) angulata, Zhou, 2014

Zhou, Jin, 2014, A new species of Scolelepis (Polychaeta: Spionidae) from Chinese seas, Raffles Bulletin of Zoology 62, pp. 490-495 : 491-494

Scolelepis (S.) angulata , new species

( Figs. 3–4 )

Type material. Holotype: ECSFRI 100196 (1 c), 32°59.469'N, 120°53.014' E, 9 May 2012, coll. Jin Zhou. Paratypes: ECSFRI 100125 (1 af), 32°59.236' N, 120°53.656' E, 8 November 2011, coll. Jin Zhou ; ECSFRI 100126 (1 af), 32°57.004' N, 120°53.021' E, 4 November 2011, coll. Jin Zhou ; ECSFRI 100127 (1 af+3 f), 32°39.251' N, 120°32.046' E, 16 November 2011, coll. Jin Zhou ; ECSFRI 100146 (2 af+2 f), 32°56.642' N, 120°53.617' E, 24 May 2012, coll. Zengling Ma ; ECSFRI 100149 (1 af), 32°58.405' N, 120°53.756' E, 22 May 2012, coll. Zengling Ma ; ECSFRI 100151 (1 af+12 f), 32°57.988' N, 120°55.228' E, 22 May 2012, coll. Zengling Ma ; ECSFRI 100158 (1 af+3 f), 32°38.037'N, 120°58.112' E, 27 May 2012, coll. Yuange Chen ; ECSFRI 100169 (1 af+1 pf), 32°38.758' N, 120°31.232' E, 27 May 2012, coll. Yuange Chen ; ECSFRI 100131 (1 f), 32°56.588' N, 120°53.672' E, 25 May 2012, coll. Yuange Chen ; ECSFRI 101029 (1 af), 32°38.108' N, 121°04.539' E, 7 August 2012, coll. Jin Zhou ; ECSFRI 101030 (1 af), 32°59.128' N, 120°53.076'E, 8 August 2012, coll. Jin Zhou ; ECSFRI 101031 (1 af), 32°58.472' N, 120°53.169' E, 8 August 2012, coll. Jin Zhou ; ECSFRI 101032 (1 af+2 f), 32°57.964' N, 120°56.004' E, 8 August 2012, coll. Jin Zhou ; ECSFRI 101033 (3 af+6 f+1 pf), 32°57.938' N, 120°55.242' E, 8 August 2012, coll. Jin Zhou ; ECSFRI 101034 (1af), 32°57.966' N, 120°55.119'E, 8 August 2012, coll. Jin Zhou ; ECSFRI 101041 (3 af+2 f), 32°37.232' N, 120°34.102' E, 14 October 2012, coll. Jin Zhou ; ECSFRI 101042 (2 af), 32°37.698' N, 120°33.762' E, 14 October 2012, coll. Jin Zhou ; ECSFRI 101069 (2 af), 20°01.128' N, 107°42.006' E, 4 March 2012, coll. Wei Tian ; ECSFRI 101070 (3 af+4 f), 20°01.962' N, 107°42.539' E, 4 March 2012, coll. Wei Tian ; ECSFRI 101071 (1 af), 20°04.576' N, 107°42.378' E, 7.5 m, sandy mud, 8 March 2012, coll. Wei Tian ; ECSFRI 101093 (2 af+2 f), 20°01.389′ N, 107°42.908' E, 24 October 2012, coll. Wei Tian ; ECSFRI 101096 (3 af), 20°03.567' N, 107°43.855' E, 26 October 2012, coll. Wei Tian ; ECSFRI 102026 (2af), 32°56.117′ N, 120°55.605′ E, 14 October 2013, coll. Jin Zhou ; ECSFRI 102027 (2af), 32°56.135' N, 120°55.680' E, 14 October 2013, coll. Jin Zhou ; ECSFRI 102028 (4af), 32°58.002' N, 120°55.356' E, 14 October 2013, coll. Junxiang Liu.

Description of holotype (ECSFRI 100196). Specimen complete, 0.76 mm wide and 12.0 mm long for 74 setigers. Color in alcohol yellowish. Body wide anteriorly, tapering posteriorly. Prostomium anteriorly inflated, with distinct medial point. A horizontal gap present on prostomium (near anterior margin of setiger 1), leaving posterior caruncle as a triangular structure. Posterior caruncle dark coloured, compared to the anterior region of prostomium. Caruncle extending posteriorly to anterior margin of setiger 2. Occipital tentacle absent. Peristomium long, distinct from setiger 1, forming well-developed lateral wings ( Fig. 3A, B ). Proboscis not observed. Palps missing.

Parapodia of setiger 1 well developed, notopodial postchaetal lamellae triangular and neuropodial postchaetal lamellae rectangular, with capillary chaetae in both rami ( Fig. 3D ). Branchiae present from setiger 2, continuing posteriorly to setiger 46. Branchiae fused with notopodial postchaetal lamellae along about 80% of length; degree of fusion decreasing in posterior setigers. Notopodial postchaetal lamellae long, narrow in anterior setigers ( Fig. 3E, F ), becoming round in posterior setigers ( Fig. 3G ). Neuropodial postchaetal lamellae oval on setigers 2–3, rounded on following setigers; becoming low and round from around setiger 30 to posterior setigers. Notch present from setiger 29, dividing neuropodial lamellae into two lobes from setiger 34. On following setigers lamellae divided into square interramal lobe and small low, rounded ventral lobe ( Fig. 3H ). Neuropodial prechaetal lamellae thick and round, from setiger 2 to posterior setigers; smaller than corresponding neuropodial postchaetal lamellae.

All anterior chaetae sheathed capillaries, arranged in two rows on both rami; anterior row thick, granulated, with obvious sheaths, posterior row thin with narrow sheaths ( Fig. 3I, J ). Neuropodial hooded hooks from setiger 48, bidentate, with open hoods ( Fig. 3K, L ), 6–12 in a series, accompanied by capillaries. Notopodial hooded hooks absent.

Pygidium cushion-like, without lateral anal cirri ( Fig. 3M ).

Variability. Paratypes 6.7–12.9 mm long (mean length: 10.2±1.8, n=29) and 0.4–0.9 mm wide. Prostomium anteriorly

inflated, with clear medial point in all examined materials ( Fig. 4A ). Part of proboscis observed in some paratypes ( Fig. 3C ). Palps observed in some paratypes, usually reaching no farther than setiger 3. Palps slender, with basal sheath, cilia not observed at bases of sheaths ( Fig. 4B, C ). Eyes absent. Branchiae fused with notopodial postchaetal lamellae along about 80% of length in anterior and middle regions of body ( Fig. 4D ). Number of branchiae 42–50. All specimens with neuropodial lamellae rounded on anterior setigers, developing notch around setigers 29–36 ( Fig. 4E ). Notch becoming deeper, dividing lamellae into separate lobes around setigers 35–38. Neuropodial hooded hooks present from setigers 32–48, numbering 5–14 in a series ( Fig. 4F ). Notopodial hooded hooks absent in all type specimens. All specimens have only bidentate hooded hooks.

Etymology. From the Latin word angulus, referring to the prostomium with short lateral angles.

Remarks. Scolelepis (S.) angulata , new species, differs from its allied species in the presence of short lateral angles of prostomium, notochaetae on setiger 1, and bidentate hooded hooks. In the genus Scolelepis , only S. (S.) occipitalis Blake & Kudenov, 1978 is known to have a similar kind of prostomium. However, the new species differs from the latter species by lacking the posteriorly flattened, irregularly shaped occipital process, by having notochaetae on setiger 1, and the presence of bidentate hooded hooks rather than quadridentate hooded hooks. Neuropodial hooded hooks begin to occur from setigers 32–48.

Williams (2007) suggested that palp ciliation patterns, which can be classified into four morphological types, are of taxonomic importance within this genus. To date, a total of nine Scolelepis species were described with taxonomic information of palp ciliation patterns using SEM observations. Cilia are commonly located on the ventral surface from the middle part of the palp to the sheath. However, cilia were not found in Scolelepis (S.) angulata , new species, in this study, suggesting that not all Scolelepis species have cilia on the surface of the palps or that palp ciliation patterns in this new species need to be re-evaluated. The overall morphology of the palp of the new species also differs from the four Scolelepis species recorded in Williams (2007), the muscles of the palp in the new species were generally in horizontal arrangement ( Fig. 4B, C ) while those in the latter were longitudinally aligned.

Scolelepis (S.) angulata , new species, was found in the South China Sea and the Yellow Sea , China and therefore could be considered as a subtropical or warm temperate species. However , it was not found in the tidal flats or shallow subtidal waters in the East China Sea (located between the South China Sea and the Yellow Sea , China). This was probably due to the critical selection of sediment types by this species. The new species inhabits intertidal zones and shallow subtidal waters characterised by sandy mud (approximate mean grain size: 0.4 mm), while most sediments in the East China Sea were mud (most of intertidal flats in the Zhejiang Province) or coarse sand (most of intertidal flats in the southern Fujian Province) .

Distribution. Intertidal flats and shallow subtidal waters in the South China Sea and the Yellow Sea, China on sandy mud bottoms.

Figures

Fig. 3. Scolelepis (S.) angulata, new species, Paratype, ECSFRI 100196: A, anterior end, dorsal view; B, anterior end, lateral view; C, anterior end, lateral view; ECSFRI 100169: D, parapodia of setiger 1, anterior view; E, parapodia of setiger 2, anterior view; F, parapodia of setiger 3, anterior view; G, parapodia of setiger 4, anterior view; H, parapodia of setiger 49, anterior view; I, notopodial seta from anterior row of setiger 4; J, notopodial seta from posterior row of setiger 4; K, neuropodial hooded hook from setiger 48, lateral view; L, neuropodial hooded hook from setiger 48, anterior lateral view; M, pygidium, dorsal view. Scale bars: A, B = 600 μm; C, M = 120 μm; D–H = 250 μm; I, J: 60 μm; K, L = 100 μm.

Fig. 4. Scolelepis (S.) angulata, new species.A, anterior end, dorsal view (Paratype, ECSFRI 100126), arrow indicates short lateral angles; B, overall view of palp, ventral-lateral view, arrow indicates sheath of palp (Paratype, ECSFRI 102026); C, basal part of palp, ventral-lateral view (Paratype, ECSFRI 102026); D, branchiae in middle region of body, dorsal view, arrow indicates sheath of palp (Paratype, ECSFRI 100126); E, parapodia of setigers 45–47, lateral view (Paratype, ECSFRI 100126); F, hooded hooks of setiger 55, lateral view (Paratype, ECSFRI 100126). Scale bars: A = 200 μm; B, =150μm; C = 15 μm; D = 800 μm; E = 400 μm; F = 15 μm.