Pectinaria dayaensis, Zhang & Hutchings & Qiu, 2022

Zhang, Jinghuai, Hutchings, Pat & Qiu, Jian-Wen, 2022, Pectinariidae (Annelida, Polychaeta) from the coastal waters of China, with description of new species and new records, Zootaxa 5151 (1), pp. 1-74 : 36-37

Pectinaria dayaensis n. sp.

Figs 17 ; 19–21 .

Material examined. Holotype: SCSMBC030911 (tissue sample sequenced), complete, Daya Bay, northern South China Sea , Guangdong Province, 114°33'13.0"E 22°35'30.0"N, 11 m, mud, coll. J. Zhang, Y. Gao & K. Chen, Jun 2015, sta. D05 . Paratypes: SCSMBC030913, 1 spec. complete, Daya Bay, northern South China Sea , Guangdong Province, 114°45'15.2"E 22°31'59.9"N, 17 m, mud, coll. J. Zhang, Apr 2008, sta. DS23. SCSMBC030915, 1 spec. complete, mounted for SEM, Daya Bay , northern South China Sea, Guangdong Province, 114°33'14.0"E 22°35'29.0"N, 13 m, mud, coll. J. Zhang, Feb 2014, sta. DS00. SCSMBC030912, 1 spec. complete, mounted for SEM, Daya Bay , northern South China Sea, Guangdong Province, 114°33'13.0"E 22°35'30.0"N, 11 m, mud, coll. J. Zhang, Y. Gao & K. Chen, Jun 2015, sta. D05. SCSMBC030916 and SCSMBC030917, 2 specs, both distorted, Daya Bay , northern South China Sea, Guangdong Province, 114°33'10.8"E 22°35'34.8"N, 10 m, muddy sand, coll. J. Zhang, Y. Gao & K. Chen, Mar 2015, sta. D05. SCSMBC030918, 1 spec. complete, Daya Bay , northern South China Sea, Guangdong Province, 114°38'49.2"E 22°31'40.8"N, 20 m, muddy sand, coll. J. Zhang, Y. Gao & K. Chen, Jun 2015, sta. D01. SCSMBC030919, 1 spec. complete, Daya Bay , northern South China Sea, Guangdong Province, 114°39'49.9"E 22°40'04.0"N, 12.2 m, mud, coll. J. Zhang, Aug 2019, sta. ZQ056 .

Non type material examined. SCSMBC030928, 1 spec. complete, distorted, Daya Bay, northern South China Sea , Guangdong Province, 114°31'06.6"E 22°34'31.5"N, 9 m, mud, coll. J. Zhang, Apr 2008, sta. DS28. SCSMBC030923, SCSMBC030924, SCSMBC030925, and SCSMBC030927, 4 specs complete, distorted, Daya Bay , northern South China Sea , Guangdong Province, 114°31'06.6"E 22°34'31.4"N, 8 m, mud, coll. J. Zhang, Aug 2009, sta. DS28. SCSMBC030926, 1 spec. complete, but with distorted body, Daya Bay , northern South China Sea , Guangdong Province, 114°33'14.0"E 22°35'29.0"N, 12 m, mud, coll. J. Zhang, Jan 2014, sta. DS00. SCSMBC030920 and SCSMBC030921, 2 specs complete, both distorted, Daya Bay , northern South China Sea , Guangdong Province, 114°33'10.8"E 22°35'34.8"N, 10 m, muddy sand, coll. J. Zhang, Y. Gao & K. Chen, Mar 2015, sta. D05. SCSMBC030922, 1 spec. complete, but with distorted body, Daya Bay , northern South China Sea , Guangdong Province, 114°39'25.2"E 22°44'49.2"N, 8 m, mud, coll. J. Zhang, Y. Gao & K. Chen, Jun 2015, sta. D14. SCSMBC030914 (tissue sample sequenced), 1 spec. complete, but with distorted body, Daya Bay , northern South China Sea , Guangdong Province, 113°48'58.0"E 22°13'34.0"N, 23.8 m, mud, coll. J. Zhang & X. Lyu, Aug 2020, sta. SZ10. TIO908 SUMST09 H08, 1 spec. complete, distorted, Beibu Gulf, 109°05'54.0"E 17°49'15.0"N, 74 m, coll. Xiamen University, Experiment 2, Aug 2006, sta. H08 .

Description. Preserved specimen pale in colour, conical in shape ( Figs 19A–C ; 20A ). Body length 4.6–28.1 mm (holotype 28.1 mm) including paleae and scaphe, width 0.8–4.3 mm (holotype 4.3 mm) at cephalic regions.

Cephalic veil semicircular, free from operculum, with 10–21 smooth cirri (holotype 21) on anterior and lateral margins ( Figs 19E ; 20B ). Pair of ear-shaped lobes adjacent to both sides of dorsal base of cephalic veil ( Fig. 20B ). Buccal tentacles with long mid-groove, arising from posterior to cephalic veil, extending beyond margin of cephalic veil ( Figs 19E ; 20B, G ).

Operculum semicircular; dorsal and lateral margins well developed, smooth; ventral margin (opercular ridge) with 11–14 pairs of golden paleae (holotype left 13, right 12), curved dorsally, acute with extended tips ( Figs 19D ; 20B–C ).

First pair of tentacular cirri extending beyond paleae, with annuli, arising from connection of opercular margin and paleal ridge ( Figs 19D–E ; 20C ). Pair of small ventro-lateral lappets present behind tentacular cirri, near cephalic veil, on segment 1 ( Figs 19E ; 20B ). Ventral region of segment 1 covered by ventral lobes of segment 2 ( Figs 19E ; 20B ).

Second pair of tentacular cirri almost same size with 1 st pair of tentacular cirri, extending beyond opercular anterior margin, with annuli, on latero-median connecting ridge on segment 2, inserted more dorsally than 1 st pair of tentacular cirri ( Figs 19D–E ; 20C ). Pair of narrow ventro-lateral lobes and pair of broad ventral lobes on segment 2; ventro-lateral lobes connected with 2 nd pair of tentacular cirri, separated from these by shallow groove; ventral lobes smooth about 3x width of ventro-lateral lobes, separated by narrow groove. Dorsal lobe absent on segment 2 ( Figs 19D ; 20C ).

Comb-like branchiae on segments 3–4, consisting of series of dense, flat lamellae. Branchiae on segment 3 larger and inserted more ventrally than those of segment 4 ( Figs 19D–E ; 20C, E–F ). Pair of dorso-lateral glandular pads present adjacent to branchiae on segments 3 and 4 respectively; dorso-lateral glandular pads on segment 3 more developed than those of segment 4 ( Figs 19D ; 20C ).

Distinct ventral glandular lobes present on segments 3–6, becoming progressively more lateral and broader on segments 3–5 ( Figs 19D–E ; 20B–C ). Segment 3 with broad ventral lobe with slightly shallow mid-indentation, about 1/3 width of ventral lobe. Segment 4 with pair of ventro-lateral lobes and a mid-ventral lobe, separated from these by deep groove; each ventro-lateral lobe with a large lateral hump adjacent to branchia and a relatively small and more acute hump off mid ventral lobe; mid-ventral lobe broad rectangular almost equal or much broader than ventro-lateral lobes, with pair of papillae adjacent to corners ( Figs 19F ; 20D–E ). Segment 5 with pair of ventro-lateral lobes and pair of short mid-ventral lobes about 1/3 width of ventro-lateral lobes, separated by shallow grooves. Segment 6 with pair of broad ventro-lateral lobes (distorted), separated by shallow grooves.

Notopodia other than those of segment 1 which bear paleae, on segments 5–20 (16 pairs), each bearing two kinds of notochaetae; one winged from anterior row, bordered with serrations along distal portion, short, covered progressively with more spines from about middle to front of wing, on anterior surface; posterior row with stout, long and straight chaetae, tapering to an acute tip, covered progressively with more spines from mid-anterior portion to tip, on anterior surface ( Fig. 21A–B ). Neuropodia, 13 pairs on segments 8–20, each with raised torus with a transverse row of uncini; each uncinus with U-shaped anterior peg embedded into torus, several rows of minor teeth, 3–4 longitudinal rows of major teeth, each with about seven teeth ( Fig. 21C–H ), with more longitudinal rows of major teeth on ventral uncini of neuropodia than dorsal ones. Segment 21 with pair of broad lateral lobes without chaetae, each lateral lobe with a transverse row of continuous numerous lappets, size of lappets decreases from ventrum to dorsum ( Figs 19G, I ; 20H–I ).

Scaphe long ovoidal (distorted in holotype), flattened dorsally; with five pairs of lobes on lateral-posterior margin including three pairs of narrow anterior lobes, 4 th pair with relatively broad lobes with acute end, and pair of rounded more posterior lobes with continuous cirri on lateral-posterior margins, 1 st cirrus longer than following cirri ( Figs 19G–I ; 20H–K ). Anal flap long tongue-shaped, with numerous cirri on lateral-posterior margin; with long, narrow, mid-dorsal anal cirrus ( Figs 19I, K ; 20J–K ). Scaphal hooks 2–4 pairs (holotype 4 pairs), amber in colour, hooked, distinctly curved dorsally, with acute tip, arranged in a straight row almost perpendicular to dorsal margin of scaphe ( Figs 19K ; 20J ). Dorsal margin of scaphe smooth, slightly arched dorsally.

Tube not collected.

Methyl Green stained body distinctly green on cirri of cephalic veil, ventral-lateral lappets on segment 1, ventral lobes of segments 2–6, base of 2 nd pair of tentacular cirri, dorso-lateral pads of segments 3–4, ventral region of some neuropodia, regions between segment 20 and scaphe, and ventral regions of scaphe ( Fig. 19 ).

Type locality. Daya Bay , northern South China Sea ( Fig. 17 ) . Other specimens were collected in Beibu Gulf , northern South China Sea .

Habitat. Collected in mud or muddy sand sediment from 8–74 m.

Etymology. The species is named after the type locality from Daya Bay, northern South China Sea.

Remarks. The new species Pectinaria dayaensis n. sp. can be identified by the following characters: cephalic veil free from operculum, dorsal and lateral margins of semicircular operculum smooth, branchiae present on segments 3–4, mid-ventral lobe of segment 4 broad rectangular almost equal or much broader than ventro-lateral lobe and with pair of papillae adjacent to corners, capillary notochaetae on segments 5–20, neurochaetae (uncini) on segments 8–20, with 3–4 longitudinal rows of major teeth on uncinus. Pectinaria dayaensis n. sp. is very similar to P. xiukaii n. sp. and P. lizhei n. sp. with regards to the scaphal characters with continuous cirri on lateral-posterior margins on the last lobe of scaphe and numerous lappets or cirri on anal flap. They can be distinguished by the mid-ventral lobe on segment 4, specimen of P. dayaensis n. sp. has a broad mid-ventral lobe almost equal or much broader than ventro-lateral lobe; whereas segment 4 of P. xiukaii n. sp. has a narrow mid-ventral lobe about 1/2 width of ventro-lateral lobes. Segment 4 of P. lizhei n. sp. also has a broad mid-ventral lobe, almost same width with ventro-lateral lobe, but has 5–6 continuous triangular lappets on the mid-ventral lobe. Pectinaria dayaensis n. sp. only has a pair of papillae at the corners of mid-ventral lobe. Pectinaria lizhei n. sp. can be easily distinguished from other similar species which are recorded from Chinese waters. Pectinaria torquata Zhang & Qiu, 2017 has a distinct complete dorsal lobe on segment 2, whereas P. dayaensis n. sp. lacks a dorsal lobe on segment 2. Pectinaria antipoda Schmarda, 1861 and P. papillosa Caullery, 1944 have capillary notochaetae on segments 5–21, whereas P. dayaensis n. sp. has capillary notochaetae on segments 5–20. The number of pairs of paleae, and number of scaphal hooks of P. dayaensis n. sp. are significantly correlated with increasing body size ( Fig. 22 ). The number of cirri on cephalic veil of P. dayaensis n. sp. also increases with body size, but not significantly ( Fig. 22 ).

Figures

FIGURE 17. Map illustrating the distribution of Pectinaria torquata Zhang & Qiu, 2017, P. dayaensis n. sp., P. lizhei n. sp. and P. xiukaii n. sp. in the coastal waters of China

FIGURE 19. Pectinaria dayaensis n. sp. Methyl Green stained body of Holotype (SCSMBC030911): A. Dorso-lateral view of entire body; B. Ventral view of entire body; C. Dorsal view of entire body; D. Dorso-lateral view of anterior end; E. Ventral view of anterior end; F. Ventral view of segment 4. G. Lateral view of posterior end; H. Ventral view of posterior end; I. Dorsal view of posterior end; J. Scaphal hooks; L. Anal flap. Abbreviations: ac, anal cirrus; af, anal flap; br, branchiae; bt, buccal tentacles; cv, cephalic veil; dlp, dorso-lateral pad; lh, lateral hump; nep, neuropodium; op, operculum; or, opercular rim; p, paleae; s, segment; sc, scaphe; sh, scaphal hooks; tc, tentacular cirri; vl, ventral lappet.

FIGURE 20. Pectinaria dayaensis n. sp. Paratype (SCSMBC030912), under the SEM: A. Lateral view of entire body; B. Ventral view of anterior end; C. Dorso-lateral view of anterior end; D. Ventral view of segment 4; E. Branchiae; F. Close up of lobe on branchia; G. Close up of buccal tentacle; H. Ventro-lateral view of posterior end; I. Dorso-lateral view of posterior end; J. Dorsal view of anal flap; K. Posterior view of scaphe; L. Scaphal hooks. Abbreviations: ac, anal cirrus; af, anal flap; br, branchiae; bt, buccal tentacles; cv, cephalic veil; dlp, dorso-lateral pads; lel, lateral ear-shaped lobe; lh, lateral hump; ll, lateral lobe; mvl, mid-ventral lobe; nep, neuropodium; op, operculum; or, opercular rim; p, paleae; s, segment; sc, scaphe; sh, scaphal hooks; tc, tentacular cirri; vl, ventral lappet; vll, ventro-lateral lobe.

FIGURE 21. Pectinaria dayaensis n. sp. chaetae of Paratype (SCSMBC030912), under the SEM: A–B. Close ups of notochaetae on segment 8; C. Dorsal uncini of neuropodia on segment 8; D. Median uncini of neuropodia on segment 8; E. Ventral uncini of neuropodia on segment 8; F. Mid-dorsal uncini of neuropodia on segment 20; G. Median uncini of neuropodia on segment 20; H. Ventral uncini of neuropodia on segment 20.

FIGURE 22. Relationship between body width and body length, number of cirri on cephalic veil, number of pairs of paleae, number of pairs of scaphal hooks, for Pectinaria dayaensis n. sp.