Pectinaria plurihamus ( Choi, Jung & Yoon, 2017 )

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 : 56-62

publication ID	https://doi.org/ 10.11646/zootaxa.5151.1.1
publication LSID	lsid:zoobank.org:pub:135CC8D7-CAFA-4B23-9006-AB8613E982A0
persistent identifier	https://treatment.plazi.org/id/039E87CF-FFC6-FFCD-C39A-F970BD1BFC7C
treatment provided by	Plazi
scientific name	Pectinaria plurihamus ( Choi, Jung & Yoon, 2017 )
status

Treatment

Pectinaria plurihamus ( Choi, Jung & Yoon, 2017)

Type locality. South Korea

Figs 36–39 View FIGURE 36 View FIGURE 37 View FIGURE 38 View FIGURE 39

Lagis plurihamus Choi, Jung & Yoon, 2017: 279–286 View in CoL , Figs 1–2 View FIGURE 1 View FIGURE 2 in Choi et al. 2017.

Material Examined. SCSMBC030940, SCSMBC030934, SCSMBC030935, SCSMBC030936, SCSMBC030937 (mounted for SEM), SCSMBC030938 , and SCSMBC030939, 7 specs, complete, First Beach , Qingdao, Yellow Sea, Shandong Province, China, 120°20'22.9"E 36°02'58.6"N, intertidal, sand, coll. D. Yang, X. Wu & D. Yang, Jul 2020. TIO908 AUTST02 GoogleMaps C701, 1 spec. complete, northern Yellow Sea , Liaoning Province, 122°06'29.5"E 38°58'05.3"N, 27 m, mud, coll. study group of benthos, Ocean University of China, Oct 2007, sta. C701. TIO908 SPRST02 GoogleMaps C801,

1 spec. complete, the northern Yellow Sea , Liaoning Province, 122°13'20.2"E 39°08'09.4"N, 15 m, silt, coll. study group of benthos, Ocean University of China, Apr 2007, sta. C801. TIO908 SPRST02 GoogleMaps C902, 1 spec. complete, mounted for SEM , the northern Yellow Sea , Liaoning Province, 122°30'16.5"E 39°11'10.5"N, 18 m, muddy sand, coll. study group of benthos, Ocean University of China, Apr 2007, sta. C902. Type material was not available for examination GoogleMaps .

Description. Preserved specimen pale in colour, conical in shape ( Figs 37A–B View FIGURE 37 ; 38A View FIGURE 38 ). Body length 4.4–19.5 mm including paleae and scaphe, width 0.7–3.6 mm at cephalic regions.

Cephalic oval, free from operculum, with 8–12 smooth cirri on anterior and lateral margins ( Figs 37C View FIGURE 37 ; 38B View FIGURE 38 ). Pair of ear-shaped lobes adjacent to both sides of dorsal base of cephalic veil between cephalic veil and segment 1. Buccal tentacles short with wide mid-groove; arising from lateral and anterior margins of buccal cavity, posterior to cephalic veil; extending to margin of cephalic veil ( Figs 37C–D View FIGURE 37 ; 38B–C, J View FIGURE 38 ).

Operculum semicircular; dorsal and lateral margins well developed, smooth; ventral margin (opercular ridge) with 10–17 pairs of golden paleae, curved dorsally, acute, with extended tips ( Figs 37D–E View FIGURE 37 ; 38C View FIGURE 38 ) and with a lappet in between rows of paleae ( Fig. 38D View FIGURE 38 ).

First pair of tentacular cirri extending slightly beyond paleae, with annuli, arising from connection of opercular margin and paleal ridge ( Figs 37A–B View FIGURE 37 ; 38A–C View FIGURE 38 ). Pair of small ventral-lateral lappets present behind tentacular cirri, near cephalic veil, on segment 1 ( Figs 37C View FIGURE 37 ; 38B View FIGURE 38 ). Ventral region of segment 1 covered by buccal tentacles and ventral lobes of segment 2 ( Figs 37A–B View FIGURE 37 ; 38B View FIGURE 38 ).

Second pair of tentacular cirri almost same size with 1 st pair, extending beyond opercular anterior margin, with annuli, on latero-median connecting ridge of segment 2, inserted more dorsally than 1 st pair ( Figs 37C View FIGURE 37 ; 38B–C View FIGURE 38 ). Pair of broad ventro-lateral lobes and narrow mid-ventral lobe with papillae about 1/4 width of ventro-lateral lobes; ventro-lateral lobes connected to 2 nd pair of tentacular cirri, separated from these by shallow groove ( Figs 37C View FIGURE 37 ; 38B View FIGURE 38 ). Dorsal lobe absent on segment 2 ( Figs 37D–E View FIGURE 37 ; 38C View FIGURE 38 ).

Comb-like branchiae on segments 3–4, consisting of a series of dense, flat lamellae. Branchiae on segment 3 larger and inserted more ventrally than those of segment 4 ( Figs 37C–D View FIGURE 37 ; 38C, E–F View FIGURE 38 ). Pair of small 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 37D–E View FIGURE 37 ; 38C View FIGURE 38 ).

Distinct ventral glandular lobes present on segments 3–6, and becoming progressively more lateral and broader ( Figs 37C–D View FIGURE 37 ; 38B–C View FIGURE 38 ). Segment 3 with pair of broad ventro-lateral lobes and narrow mid-ventral lobe about 1/2 width of ventro-lateral lobes, separated by deep groove; mid-ventral lobe slightly globular dorsally. Segment 4 with pair of ventro-lateral lobes and a mid-ventral lobe about 1/3 width of ventro-lateral lobes, separated from these by deep groove; each ventro-lateral lobe smooth without hump adjacent to branchia. Segment 5 with pair of ventrolateral lobes, separated by shallow broad mid-groove. Segment 6 with pair of broad ventro-lateral lobes, separated by shallow and broad mid-groove.

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 acute tip, covered progressively with more spines from mid-anterior portion to tip, on anterior surface ( Fig. 39A–F View FIGURE 39 ). Neuropodia, 12 pairs on segments 8–19, 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, 4–5 longitudinal rows of major teeth, each with about seven teeth ( Fig. 39A, G–H View FIGURE 39 ), with more rows of major teeth on ventral uncini than dorsal ones within an individual row. Pair of broad lateral lobes adjacent to notochaetae on segment 20, smaller than neuropodia on segment 19. Segment 21 with pair of broad achaetous lateral lobes ( Figs 37F–H View FIGURE 37 ; 38G View FIGURE 38 ).

Scaphe long ovoidal, flattened dorsally; with six pairs of lobes on lateral-posterior margin including three pairs of narrow anterior lobes with rounded ends, following two pairs of relatively broad lobes with rounded margin, and the last pair of lobes with bluntly serrated (appearing as continuous rounded lobes) posterior margins ( Figs 37F–H View FIGURE 37 ; 38G–I View FIGURE 38 ). Anal flap short tongue-shaped, with numerous cirri or lappets on lateral-posterior margin, with enlarged mid to posterior dorsally anal cirrus ( Figs 37G–H View FIGURE 37 ; 38H–I View FIGURE 38 ). Scaphal hooks 5–12 pairs, amber in colour, slightly hooked, curved dorsally, with acute tip, arranged in a pair of rows on dorsal margin from first pair of dorso-lateral lobes of scaphe to mid dorsal lobe of scaphe, outer hooks larger than inner ones ( Figs 37F View FIGURE 37 ; 38K–L View FIGURE 38 ). Mid-dorsal margin of scaphe smooth with distinctly bulged narrow lobe, folded back onto dorsum of scaphe ( Fig. 38K View FIGURE 38 ).

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, lateral regions between segment 20 and scaphe, and ventral regions of scaphe ( Fig. 37 View FIGURE 37 ).

Distribution. Korean waters, northern Yellow Sea ( Fig. 36 View FIGURE 36 ).

Habitat. Collected in mud or muddy sand sediment from intertidal to shallow water.

Remarks. These specimens can be identified to Pectinaria plurihamus ( Choi, Jung & Yoon, 2017) by the following characters: cephalic veil free from operculum, dorsal and lateral margins of semicircular operculum smooth, branchiae present on segments 3–4, capillary notochaetae on segments 5–20, neurochaetae (uncini) on segments 8–19, 4–5 longitudinal rows of major teeth on uncini, the last lobe with bluntly crenulated posterior margins on on scaphe, anal flap with numerous cirri or lappets on lateral-posterior margin, anal cirrus enlarged. We confirm that cephalic veil of P. plurihamus is free from operculum and a pair of ear-shaped lobes present adjacent to both sides of dorsal base of cephalic veil between cephalic veil and segment 1. Choi et al. (2017) placed the species in the genus Lagis based on their observation of the cephalic veil being partially fused to operculum following the prior description ( Fauvel 1932; Sun & Qiu 2012). However, they did not describe in detail the fusion between the cephalic veil and the operculum. The pair of ear-shaped lobes adjacent to both sides of dorsal base of cephalic veil between cephalic veil and segment 1 could be interpreted as a connection between the cephalic veil and the operculum, whereas the pair of ear-shaped lobes of Lagis are between the buccal cavity and segment 1 ( Fig. 13B, D View FIGURE 13 & Fig. 3C View FIGURE 3 in Zhang & Hutchings 2019). Based on the cephalic veil being free from operculum, we have transferred this species to Pectinaria . Pectinaria plurihamus can not be distinguished from Pectinaria dimai Zachs, 1933 from North Japan Sea as the original description of P. dimai is brief. So as of now P. dimai can be only identified to genus based on the available characters ( Zachs, 1933), and it is necessary to obtain additional material from the type locality or locate the type material to confirm its correct identity. The species Pectinaria plurihamus has been accepted, and we identify the specimens from the northern Yellow Sea, China as this species and this represents a new record for Chinese waters. Pectinaria plurihamus can be distinguished from other recorded species of pectinariids from Chinese waters by the enlarged anal cirrus and neurochaetae (uncini) on segments 8–19. Pectinaria plurihamus is similar to Lagis crenulatus Sun & Qiu, 2012 from Hong Kong as they both have capillary notochaetae on segments 5–20, neurochaetae (uncini) on segments 8–19, but L. crenulatus lacks any branchiae on segments 3–4.