Amphictene alata Zhang, Zhang & Qiu, 2015

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 : 9-12

Amphictene alata Zhang, Zhang & Qiu, 2015

Figs 1–2 ; Figs 1–3 in Zhang et al. (2015)

Material examined. Paratypes: SCSMBC006678, 1 spec. complete, distorted, Daya Bay, northern South China Sea , Guangdong Province, 114°35'19.0"E 22°35'17.0"N, 14.5 m, mud, coll. J. Zhang, May 2013, sta. ZQ002. SCSMBC006680, 1 spec. complete, distorted, Daya Bay , northern South China Sea, Guangdong Province, 114°31'00.0"E 22°34'09.0"N, 9 m, mud, coll. Y. Wang, Oct 2013, sta. S3. SCSMBC006681, 1 spec. posteriorly incomplete, distorted, Daya Bay , northern South China Sea, Guangdong Province, 114°31'07.0"E 22°34'31.1"N, 9 m, mud, coll. J. Zhang, Jan 2014, sta. DS28. SCSMBC006682, 1 spec. damaged, Daya Bay , northern South China Sea, Guangdong Province, 114°40'19.0"E 22°37'29.0"N, 13 m, muddy sand, coll. J. Zhang, Aug 2014, sta. ZQ008 .

Non type material examined. SCSMBC030862, 1 spec. complete, 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. SCSMBC030863, 1 spec. complete, but dried, 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. SCSMBC030864 (tissue sample sequenced), 1 spec. incomplete, Daya Bay , northern South China Sea, Guangdong Province, 114°33'10.8"E 22°35'34.8"N, 11 m, mud, coll. J. Zhang, Y. Gao & K. Chen, Jun 2015, sta. D05. SCSMBC030865 (tissue sample sequenced), 1 spec. incomplete, distorted, Daya Bay , northern South China Sea, Guangdong Province, 114°33'10.8"E 22°35'34.8"N, 11 m, mud, coll. J. Zhang, Y. Gao & K. Chen, Jun 2015, sta. D05. SCSMBC030866 (tissue sample sequenced), 1 spec. complete, Daya Bay northern South China Sea, Guangdong Province, 114°33'10.8"E 22°35'34.8"N, 11 m, mud, coll. J. Zhang, Y. Gao & K. Chen, Jun 2015, sta. D05. SC- SMBC030867 (tissue sample sequenced), 1 spec. complete, distorted, 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. SCSMBC030868, 1 spec. complete, Daya Bay , northern South China Sea , Guangdong Province, 114°33'14.0"E 22°35'28.0"N, 12 m, mud, coll. J. Zhang, Aug 2015, sta. ZQ001. SCSMBC030869, 1 spec. complete, Daya Bay , northern South China Sea , Guangdong Province, 114°41'05.0"E 22°34'34.0"N, 18 m, mud, coll. J. Zhang, Aug 2015, sta. ZQ007 .

Description. Based on all specimens examined. Preserved specimens pale or reddish in colour, conical in shape ( Fig. 2A–B ). Body length 12.2–74.0 mm including paleae and scaphe, width 2.1–8.8 mm at cephalic regions.

Cephalic veil oval, free from operculum, with 13–16 smooth cirri on anterior margin and present on about 2/3 of lateral margins ( Fig. 2E ). Pair of ear-shaped lobes adjacent to both sides of dorsal base of cephalic veil. Buccal tentacles with deep median longitudinal grooves, arising posterior to cephalic veil from buccal cavity, extending over margin of cephalic veil ( Fig. 2E ).

Operculum semicircular; dorsal and lateral margins well developed, with about six pairs of lateral cirri and 8–13 ventral triangular lappets; ventral margin (opercular ridge) with 8–11 pairs of golden paleae, curved dorsally, with extended tips ( Fig. 2C–D ).

Segments 1–2 each with pair of tentacular cirri, annulate, tapering to tip ( Fig. 2D ). Segment 2 without dorsal and lateral lobes ( Fig. 2C ). Segments 3 and 4 each with pair of comb-like branchiae ( Fig. 2C–E ). A large ventral lobe and pair of dorso-lateral lobes (pads) with crenulated margin on segment 3 ( Fig. 2C–D ). Segment 4 with a small mid-ventral lobe and pair of larger ventro-lateral lobes with a large lateral hump adjacent to branchia, without dorso-lateral lobe ( Fig. 2C–E ).

Segments 5–20 with notopodia, each bearing two kinds of notochaetae, one winged, bordered with serrations along distal portion, covered progressively with more spines from about middle to front of wing on anterior surface, other side smooth; other stout and straight, tapering to an acute tip, covered with spines from mid-anterior portion to tip on anterior surface, other side smooth.

Segments 8–20 with neuropodia, each with a raised torus with transverse row of uncini, each uncinus with Ushaped anterior peg embedded into torus, several rows of minor teeth, and two longitudinal rows of major teeth, each with about eight teeth ( Fig. 2A–B ; Figs 1D–G & 3F–N in Zhang et al. 2015).

Scaphe ovoid, slightly convex dorsally, with two pairs of lappets on lateral margin, distinctly separated from abdomen ( Fig. 2F–H ). Scaphal hooks 18 to 40 pairs, spear-shaped, with a slightly bent tip ( Fig. 2I ). Anal tongue oval, with smooth margin extending beyond posterior scaphal margin, without anal cirrus ( Fig. 2F–H ).

Methyl Green stained body distinctly green on cephalic veil, dorsal and lateral rims of operculum, ventral lobes of segments 2–6, base of 2 nd pair of tentacular cirri, dorso-lateral pads of segment 3, neuropodia, regions between segment 20 and scaphe, margins of scaphe, and the last half of scaphal ventrum ( Fig. 2A–B ).

Distribution. This species was only collected from the type locality Daya Bay, northern South China Sea ( Fig. 1 ).

Habitat. Collected in mud or muddy sand in shallow water.

Remarks. Amphictene alata Zhang, Zhang & Qiu, 2015 is easily distinguished by a pair of dorso-lateral lobes with crenulated margin (several lobes) on segment 3. This species is characterized by the following characters: a pair of dorso-lateral lobes with a crenulated margin on segment 3, cirri or triangular lappets on opercular lateral and dorsal margin, many pairs (18 to 40) of scaphal hooks, neurochaetae on segments 8–20, capillary notochaetae on segments 5–20. This species is very similar to Amphictene japonica ( Nilsson, 1928) . Amphictene alata differs from A. japonica as it has a pair of dorso-lateral lobes with a crenulated margin on segment 3. The number of paleae, cirri on opercular rim, cirri on cephalic veil, and scaphal hooks increases with body size of A. alata , but only the numbers of scaphal hooks and paleae exhibit a significant positive correlation with body size ( Fig. 3 ). Though the types of A. alata have more pairs of scaphal hooks than A. japonica , the lowest number of pairs of A. alata is within the range of scaphal hooks of A. japonica ( Nishi et al. 2014) . This suggests that the number of pairs of scaphal hooks is not an important character for distinguishing between A. alata and A. japonica .

Figures

FIGURE 1. Map illustrating the distribution of species of Amphictene in the coastal waters of China

FIGURE 2. Amphictene alata Zhang, Zhang & Qiu, 2015 Methyl Green stained body (SCSMBC030866): A. Dorso-lateral view of distorted entire body; B. Ventral view of distorted entire body; C. Dorsal view of anterior end; D. Lateral view of anterior end; E. Ventral view of posterior end; F. Lateral view of posterior end; G. Ventral view of posterior end; H. Dorsal view of posterior end; I. Scaphal hooks. Abbreviations: af, anal flap; br, branchiae; bt, buccal tentacles; cv, cephalic veil; dlp, dorsolateral pads; dls, dorsal lobe of scaphe; nep, neuropodium; noc, notopodial chaetae; op, operculum; or, opercular rim; p, paleae; s, segment; sc, scaphe; sh, scaphal hooks; tc, tentacular cirri; vl, ventral lappet.

FIGURE 3. Relationship between body width and body length, number of pairs of paleae, number of cirri on cephalic veil, number of pairs of scaphal hooks, number of cirri on opercular rim, for Amphictene alata Zhang, Zhang & Qiu, 2015.