Review of Ampharete Malmgren, 1866 (Annelida, Ampharetidae) from China*

SUI Jixing , LI Xinzheng , ,

1 Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China

2 Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao 266071, China

3 Laboratory for Marine Biology and Biotechnology, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao 266237, China

4 University of Chinese Academy of Sciences, Beijing 100049, China

Abstract In this paper, the material of the genus Ampharete Malmgren, 1866 from China Seas (Annelida: Ampharetidae) deposited in the collections of the Marine Biological Museum of the Chinese Academy of Sciences (MBMCAS) is reviewed and previous identifi cations reassessed. In total, four species were found among all specimens examined. Material previously attributed to A. acutifrons (Grube, 1860) and A. arctica Malmgren, 1866 had been misidentifi ed and is now confi rmed as belonging to A. lindstroemi Hessle, 1917 and A. fi nmarchica (Sars, 1865), respectively; the presence of A. falcata Eliason, 1955 is also confi rmed; A. orientalis (Annenkova, 1929) is recorded for the fi rst time from China.

Keyword: Ampharete; Polychaeta; taxonomy; China

1 INTRODUCTION

Ampharetids are tubicolous, infaunal species in muds and sands at all water depths, most of the adults are 1-6 cm long (Jumars et al., 2015). Ampharetidae Malmgren, 1866 comprises approximately 230 species distributed among 63 genera, 33 of them monotypic (Read and Fauchald, 2020). Ampharete Malmgren, 1866 is the most speciose genus in the family Ampharetidae. We agree with Imajima et al. (2012) that the genus Asabellides Annenkova, 1929,

Parampharete Hartman, 1978, Pterampharete Augener, 1918 and Sabellides Milne-Edwards in Lamarck, 1838 are the junior synonyms of Ampharete. Consequently, Ampharete would include ampharetids with papillose buccal tentacles, prostomium without glandular ridges, with the middle lobe delimited by a more or less U-shaped incision, four or exceptionally three pairs of branchiae and 11 or 12 thoracic uncinigers.

Three Ampharete species were reported from the coasts of China according to the checklist of Huang (1994) and Liu (2008). They are A. acutifrons (Grube, 1860), A. arctica Malmgren, 1866 and A. reducta Chamberlin, 1920. Afterwards, Sui (2013) fi rstly reported another three species from China, A. fi nmarchica (Sars, 1865), A. lindstroemi Hessle, 1917 and A. falcata Eliason, 1955.

We have checked the Ampharete material deposited in MBMCAS, reassessed previous identifi cations and confi rmed the presence of four species in China Seas: Ampharete fi nmarchica (Sars, 1865), A. lindstroemi Hessle, 1917, A. orientalis (Annenkova, 1929) and A. falcata Eliason, 1955; A. reducta Chamberlin, 1920 is an invalid record in China because it was found in a checklist of an ecological paper fi rstly, lacking of illustrations and descriptions (Sun and Chen, 1988). A. orientalis is reported for the fi rst time from Chinese waters.

2 MATERIAL AND METHOD

All specimens were deposited in the MBMCAS. The specimens of Ampharete orientalis (Annenkova, 1929) were collected using a 1.5-m×0.5-m Agassiz trawl from the northern Yellow Sea by a quarterly sampling to investigate environmental health of Zhangzi Island in 2016. Other specimens were mainly collected from the East and South China Seas by the investigation of oil pollution in the East China Sea cruise in 1975-1976 and the National Comprehensive Oceanography Survey cruise in 1950s. The main distribution area is shown in Fig.1 (by Surfer 11 software). Specimens were fi xed in 10% formalin and then preserved in 75% ethanol. Specimens were prepared by critical point drying and covered with gold in an evaporator, and then examined and photographed with a KYKY-2800B scanning electron microscope (SEM).

3 SYSTEMATIC

Family Ampharetidae Malmgren, 1866

Genus Ampharete Malmgren, 1866

Type species: Amphicteis acutifrons Grube, 1860

Generic diagnosis: Prostomium with middle lobe delimited by incision, anteriorly rounded, without glandular ridges. Buccal tentacles papillose. Usually four pairs of cirriform, or exceptionally pinnate, branchiae. Two nephridial papillae behind branchiae. Paleae absent or present. 11 or 12 thoracic uncinigers. Glandular pads usually present.

3.1 Ampharete falcata Eliason, 1955 (f ig.2)

Ampharete falcata Eliason 1955: 3-6, fi g.1; Holthe 1986: 35-37, fi g.10, map 9; Hartmann-Schröder 1996: 492-493. Imajima et al. 2012: 82-83, fi gs.3A-I, 6C.

Specimens examined: MBM190099, 1 specimen; East China Sea, Station I-5 (the coordinates of latitude and longitude are lost); water depth: 50 m; mud and sand; September 18, 1976. MBM190100, 1 specimen; the Yellow Sea, Station 71 (35°40′03″N, 122°00′00″E); water depth: 80 m; mud and sand; 9 Oct., 1975.

Description: Length 20 mm, thorax width 1 mm without chaetae. Thorax and abdomen well defi ned. Color in alcohol pale yellow.

Prostomium broadly rounded with three lobes, without glandular ridges and eyes (Fig.2a). Buccal tentacles with long papillae. Paleae well developed, with pointed tips, 6-8 on each side. Four pairs of smooth, cirriform branchiae, separated by a wide median gap. First three branchiae in each group in a transverse row, the fourth one just behind the middle one of the three. Three pairs of branchiae of anterior transverse row originating from fused segment II+III and segment IV, posterior pair originating from segment V (Fig.2b).

Fig.1 Map of coastal areas of China, showing the locations of all Ampharete species

Notopodia beginning on segment IV, present in 14 chaetigers. Notopodia well developed, conical, bearing a bundle of winged capillary chaetae. Neuropodial uncini begin on the third chaetiger (segment VI) and continue for 12 thoracic segments. Elevated or modifi ed notopodia absent. 12 abdominal uncinigerous segments, the anteriormost three with rudimentary notopodia (Fig.2c). Uncini in abdominal segments are smaller than those of thorax. All uncini with two rows of teeth, each row with 4-5 teeth (Fig.2d). Pygidium with pair of long, lateral, cirriform anal cirri and a ring of papillae.

Distribution: North Atlantic from Southwest England and the Kattegat to Spitsbergen. Japan and China (the Yellow Sea and East China Sea). The species seems to be restricted to water depths less than 400 m.

3.2 Ampharete fi nmarchica (M. Sars, 1865)

Hartmann-Schröder & Stripp 1968; Hartmann-Schröder 1996: 293; Holthe 1986: 38; Hilbig 2000: 110-112, fi gs. 5.4; Jirkov 2001: 465; Parapar et al. 2012: 335-336, fi gs. 2, 3.

Fig.2 Ampharete falcata Eliason, 1955; MBM190099

Specimens examined: MBM190018, 1 specimen; the Yellow Sea, Station 58 (35°30′00″N, 122°23′36″E); water depth: 52 m; mud; June 25, 1976. MBM190019, 1 specimen; the Yellow Sea, Station 14 (35°20′15″N, 123°40′54″E); water depth: 77 m; mud; June 25, 1976. MBM190020, 1 specimen; the Yellow Sea, Station 61 (35°49′30″N, 122°20′36″E); water depth: 56 m; mud; June 26, 1976. MBM001738, 4 specimens; East China Sea, Station 4112 (31°00′02″N, 123°00′00″E); water depth: 52 m; mud and sand; October 25, 1959.

Diagnosis: Prostomium with middle lobe delimited by incision, without glandular ridges. Buccal tentacles papillose. Paleae long and stout with pointed tips, 12-16 on each side. Four pairs of branchiae in two groups without median gap. First three branchiae of each side in a transverse row, 4thjust behind the middle one of the three. 14 thoracic segments with notopodia and chaetae, posterior 12 also with neuropodia with uncini. 13 abdominal uncinigerous segments with small, rudimentary notopodia. Pygidium with two long cirri and a number of small papillae. All uncini with two rows of teeth, each row with 5-6 teeth.

Distribution: Widely distributed Arctic-boreal species commonly reported in the Atlantic and Pacifi c oceans.

Remarks: The specimens in the MBMCAS were misidentifi ed as Ampharete arctica Malmgren, 1866. The latter species diff ers from A. fi nmarchica in having a large median gap between the two groups of branchiae, about 30 paleae in each side and 12 abdominal uncinigerous segments.

3.3 Ampharete lindstroemi Hessle, 1917

Ampharete lindstroemi Hessle 1917: 98, plate 1, fi g.5—not Malmgren, 1867: 214 (nomen nudum); Holthe 1986: 41-42, fi g.13, map 12; Hartmann-Schröder 1996: 494; Imajima et al. 2012: 83-85, fi gs.4A-I, 6D.

Specimens examined: MBM190010, 6 specimens; Jiaozhou Bay, Station K014 (36°03′50″N, 120°19′33″E); mud; water depth: 7 m; June 20, 1981. MBM190113, 6 specimens, 1957. MBM190218, 1 specimen. Other information is lost.

Diagnosis: Prostomium with middle lobe delimited by incision, without glandular ridges, usually with 2-6 eyes. Buccal tentacles with long and slender pinnae. Paleae long and slender with pointed tips, 7-14 on each side. Four pairs of branchiae in two groups with wide median gap. First three branchiae of each side in a transverse row, 4thjust behind the middle one of the three. 14 thoracic segments with notopodia and chaetae, posterior 12 also with neuropodia with uncini. 12 abdominal uncinigerous segments, without rudimentary notopodia, dorsal cirrus papillose. All uncini with 9 teeth in 2 alternating rows over basal prow and rostral tooth. Pygidium with pair of lateral cirri and a number of small papillae.

Distribution: North Atlantic, White Sea, North Pacifi c including the Japanese coast and the Yellow Sea.

Remark: These specimens had been identifi ed incorrectly as Ampharete acutifrons (Grube, 1860). Thus, A. acutifrons can be distinguished from A. lindstroemi by the presence of long ( A. acutifrons) versus short or papillose ( A. lindstroemi) cirri in abdominal neuropodia (Parapar et al., 2012).

3.4 Ampharete orientalis (Annenkova, 1929) (Fig.3)

Asabellides orientalis Annenkova 1929: 494-495, plate XXXVIII, fi gs.50-51, plate XXXIX, fi gs.60-65. Imajima et al. 2012: 85-87, fi gs.5A-H, 6E.

Specimens examined: MBM304672. 1 specimen; the northern Yellow Sea, Station A3 (38°49′09″N, 122°23′31″E); water depth: 42 m; sand; coll. Yan J; July 20, 2016.

MBM304673, 12 specimens, the northern Yellow Sea, Station A3 (39°00′12″N, 122°35′08″E); water depth: 39 m; sand; coll. Sui J; August 21, 2016.

Description: Worm up to 19 mm long, about 1 mm wide without chaetae.

Prostomium with middle lobe delimited by incision, without glandular ridges (Fig.3a). Two eyes, one on each side of the middle lobe. Buccal tentacles with long papillae (Fig.3c). Paleae and postbranchial hooks absent (Fig.3b). Branchiae 4 pairs, cirriform, smooth, without median gap; fi rst 3 pairs arranged in transverse line, 4thpair usually displaced slightly posteriorly; bases of all branchiae fused to a single stem-like membrane. Three pairs of branchiae of anterior transverse row originating from fused segment II+III, and IV, 4thpair originating from segment V. 1 pair of nephridial papillae in segment IV, located behind the 4thpair of branchiae.

Fourteen thoracic segments with normal notopodia with winged capillary chaetae, posterior 12 ones also with neuropodia with uncini. The fi rst 3 notopodia and chaetae increasing gradually in size (Fig.3b). Ventral shields extend to the 8ththoracic unciniger. 21 abdominal uncinigerous segments, with rudimentary notopodia, dorsal cirrus absent (Fig.3d). Abdominal uncini smaller than those of thorax. Thorax and abdominal uncini with two rows of teeth, each row with 4 teeth (Fig.3e & f). Pygidium with pair of long, lateral, cirriform anal cirri and a ring of papillae.

Variation: 11 specimens of MBM304673 are juveniles, range of body length 9-11 mm, with 3 pairs of branchiae and 21 abdominal uncinigerous segments (Fig.3a); adult specimens 19 mm, with 4 pairs of branchiae and 21 abdominal uncinigerous segments. Eyes are found in our specimens, rather than being absent in Japanese specimens (Imajima et al., 2012).

Distribution: Sea of Okhotsk, Japan and the northern Yellow Sea (depth: 39 m).

Remarks: Ampharete orientalis (Annenkova, 1929) belongs to the small group of Ampharete species without paleae, formerly assigned to the genus Asabellides Annenkova, 1929. Imajima et al. (2012) confi rmed that A. orientalis is a valid species that is characterized by having unusual fused branchiae, two long anal cirri and a ring of papillae. This is the fi rst record of this species from China.

4 DATA AVAILABILITY STATEMENT

All data generated and/or analyzed during this study are included in this published article.

5 ACKNOWLEDGMENT

We thanks Dr. KOU Qi and Dr. XU Yong for their help with photography. Special thanks to three reviewers for giving us valuable comments which signifi cantly improved the manuscript.

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