Chinese Journal of Oceanology and Limnology   2017, Vol. 35 issue(4): 821-824     PDF       
http://dx.doi.org/10.1007/s00343-017-6140-3
Institute of Oceanology, Chinese Academy of Sciences
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Article Information

SUI Jixing(隋吉星), LI Xinzheng(李新正)
A new species of the genus Amphicteis (Polychaeta: Ampharetidae) from China
Chinese Journal of Oceanology and Limnology, 35(4): 821-824
http://dx.doi.org/10.1007/s00343-017-6140-3

Article History

Received May. 5, 2016
accepted in principle May. 30, 2016
accepted for publication Jun. 21, 2016
A new species of the genus Amphicteis (Polychaeta: Ampharetidae) from China
SUI Jixing(隋吉星), LI Xinzheng(李新正)        
Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China
ABSTRACT: A new species of the ampharetid genus Amphicteis, A. chinensis sp. nov., is described based on material from the East and South China Seas. The new species is distinguished from the other known species of this genus by the presence of a lobebehind the paleae. A key to distinguish all Amphicteis species and the closely related genus Paramphicteis from the Chinese seas is provided.
Key words: new species     Amphicteis     Paramphicteis     Ampharetidae     Polychaeta    
1 INTRODUCTION

The genus Amphicteis Grube, 1850, with 27 valid known species (Parapar et al., 2011; Reuscher et al., 2015), is one of the most widely distributed genera in the family Ampharetidae Malmgren, 1866. Since its creation, the genus has been well characterized (Day, 1964; Fauchald, 1977; Holthe, 1986). Paramphicteis Caullery, 1944 closely resembles the genus Amphicteis, in having glandular ridges on the prostomium, 14 thoracic uncinigerous segments, four pairs of branchiae, and notopodial cirri. It differs from the latter in that the buccal tentacles are papillose and lack paleae (Reuscher et al., 2009). Salazar-Vallejo and Hutchings (2012) also considered ornamentation (smooth, papillose, or pinnate surface) of the buccal tentacles as a generic diagnostic feature in the polychaete family Ampharetidae, Malmgren, 1866. We agree with Reuscher et al. (2015) that Pseudoamphicteis is a junior synonym of Paramphicteis. The distinction between these two genera based only on the absence or presence of the paleae seems unwarranted, because their size is very variable within the Amphicteis genus complex. Jirkov (1994, 2008) also considered the paleae to be highly variable.

Three Amphicteis and two Paramphicteis species have been recorded from Chinese seas: Amphicteis glabra Moore, 1905, A. gunneri ( M. Sars, 1835), A. scaphobranchiata Moore, 1906, Paramphicteis angustifolia (Grube, 1878), and P. sinensis (Liu, 2008; Sui and Li, 2014). According to our examination of all of the specimens deposited in the Marine Biological Museum of the Chinese Academy of Sciences (MBMCAS), the record of Amphicteis mederi Annenkova, 1929 in China (Sun, 1990) is a misidentification of P. sinensis (Sui and Li, 2014).

Recently, two Amphicteis specimens were separated out when we sorted material from the family Ampharetidae deposited in MBMCAS. These specimens represent an undescribed species. The species is described herein and proposed as a new species to science.

2 MATERIAL AND METHOD

The two specimens were collected from the East and South China Seas by the investigation of oil pollution in the East China Sea cruise in 1978 and the National Comprehensive Oceanography Survey cruise in 1959. They were fixed in 10% formalin and preserved in 75% ethanol. The specimens were photographed with Nikon AZ100 and drawn with Nikon SMZ1500. The sampling locations are shown in Fig. 1.

Figure 1 Map showing the sampling stations on the Chinese coast
3 RESULT 3.1 Systematics

Family Ampharetidae Malmgren, 1866

Genus Amphicteis Grube (1850)

Amphicteis chinensis sp. nov. (Figs. 2, 3)

Figure 2 Amphicteis chinensis sp. nov. a. anterior end, dorsal view, 30×; b. anterior end, lateral view, with large, long lobe projecting behind paleae, 30×; c. paleae, 40×; d. notopodia of thoracic chaetigers 5–6, with small conical dorsal lobe, 60×; e. 2–3 abdominal chaetigers, with rudimentary notopodia and dorsal cirrus, 30×; f. posterior region (one anal cirrus lost), ventral view, 20×.
Figure 3 Amphicteis chinensis sp. nov. a. anterior end, lateral view, 40×; b. paleae, 80×; c. branchiae, 60×; d. Last thoracic and first abdominal segments, lateral view, 50×; e. uncini, 400×.

Material examined. Holotype, complete. MBM190204, East China Sea, Station. 6 (32°09′12″N, 126°04′24″E), 105 m, sand and mud, 2nd July, 1978; Paratype, complete. MBM001700, South China Sea, Station. 6161 (18°15′00″N, 110°30′00″E), 125 m, sand and mud, 24th Nov., 1959.

Description. Holotype (MBM190204). Length 22 mm, width 3.1 mm without chaetae. Thorax and abdomen well defined; thorax approximately 1.5× width of abdomen. Tube unknown. Color in alcohol pale yellow.

Prostomium with a pair of dorsal longitudinal glandular ridges, separated by a distinct groove. Paired nuchal ridges arranged at a V-form angle (Fig. 2a). Eyes absent. Buccal tentacles smooth (Fig. 2b). First segment achaetous. Golden-yellow paleae on second segment with slender, slightly curved tip, 14–16 on each side (Figs. 2c, 3b). Pair of large, long lobes projecting behind the paleae (Figs. 2b, 3a). Four pairs of cirriform branchiae, arranged in three rows (2+1+1) (Figs. 2a, 3a and c), the first three pairs stout, disposed into two crowded groups in the third and fourth segments, separated by a median gap. Fourth pair thinner than the former, set far back from the first three in the fifth segment (third chaetigerous segment).

Notopodia begin on segment Ⅲ, continue for 17 segments, notochaetae smooth, pointed. Notopodia conical, with a small conical dorsal lobe (Figs. 2d, 3d). Notopodia and capillaries of the third to fifth segments increasing gradually in size. Neuropodial uncini begin on the fourth chaetiger (segment Ⅵ) and continue for 14 thoracic segments. Continuous ventral shields conspicuous to thoracic unciniger 10. Sixteen abdominal uncinigerous segments, with rudimentary notopodia and uncini, pinnules with tuberculate dorsal cirrus (Figs. 2e, 3d). Thoracic torus 0.5 mm long, with approximately 45 uncini. Abdominal torus 0.3 mm long, with approximately 40 uncini. All uncini similar, with a single row of three teeth (Fig. 3e). Pygidium with a pair of long cirri (Fig. 2f).

Variation. Length of paratype 26 mm, width not including chaetae 3.3 mm. Paratype only has one branchia on the fourth pair, other branchiae are lost.

Etymology. The species is named because it was found on the coast of China.

Remarks. The new species differs from the other known species of Amphicteis by the presence of a large lobe projecting behind the paleae. The new species is most similar to A. posterobranchiata Fauvel, 1932, which inhabits the seas surrounding the Arabian Peninsula. Both species share the same pattern of branchial arrangement. A. chinensis sp. nov. differs from A. posterobranchiata by having 14– 16 paleae on each side and 16 abdominal uncinigerous segments, while the latter has 20–25 paleae and 13 abdominal uncinigerous segments.

Three species of Amphicteis, A. glabra Moore, 1905, A.gunneri(Sars, 1835), and A. scaphobranchiata Moore, 1906, have been recorded from Chinese seas, according to the checklist (Huang, 1994; Liu, 2008). These species resemble the new species in having glandular ridges on the prostomium, well-developed paleae, 14 thoracic uncinigerous segments, and four pairs of branchiae. The new species differs from these species by having a large lobe projecting behind the paleae and the branchiae arranged in three rows (2+1+1), while these species have no lobe and the branchiae are arranged in two rows of two pairs (2+2). A key to all Amphicteis and Paramphicteis species from Chinese seas is provided.

Distribution. East China Sea and South China Sea (105–125 m).

Key to Amphicteis and Paramphicteis species from Chinese seas

1. Buccal tentacles papillose……………………2

Buccal tentacles smooth…………………………3

2. Paleae present…………Paramphicteis sinensis

Paleae absent………Paramphicteis angustifolia

3. A large lobe present behind the paleae on the third segment………Amphicteis chinensis sp. nov.

Lobe absent……………………4

4. One pair branchiae foliaceous………………Amphicteis scaphobranchiata

All branchiae cylindrical………………………5

5. Paleae well developed, up to 20 on each side…………………Amphicteis gunneri

Paleae slender and curved, 8–10 on each side…………………………………Amphicteis glabra

4 ACKNOWLEDGEMENT

We thank Dr. Michael Reuscher (Harte Research Institute, Texas A & M University) for providing us with important references. Many thanks to Mr. ZHANG Pengchi and Dr. GAN Zhibin (IOCAS) for their help with photography. We are also grateful to the managers of the MBMCAS for their help with specimen sorting. Many thanks to Dr. Pat Hutchings for her help in improving this manuscript. Three anonymous reviewers are thanked for their suggestions that improved the manuscript.

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