Corresponding author: Xinzheng Li (
Academic editor: C. Glasby
Sun Y, Li X (2016) A new species of
Polychaetes belonging to the family
Species of the genus
When the authors examined the Marine Biological Museum of Chinese Academy of Sciences Institute of Oceanology, Chinese Academy of Sciences
The specimens were collected during the late 1950s to early 1960s from Beibu Gulf (Tonkin Gulf), northern South China Sea. All specimens are deposited in the
Holotype, MBM010010, Beibu Gulf,
Prostomium globular, posterior margin bilobed, with two pairs of eyes, anterior pair semicircular in shape. Medial caruncle conspicuous, arising from and confluent with posterior prostomial margin, medial lobe projecting above paired lateral lobes. Parapodia biramous, rami widely separated, with single dorsal and single ventral cirrus. Branchiae dendritic, present from chaetiger 3 onwards, with more than 40 pairs.
Holotype (MBM010010) incomplete, lacking posterior part, 17 mm long, 2 mm wide excluding chaeta, with 45 chaetigers. Body elongate, nearly rectangular in cross section, tapering posteriorly. Color in alcohol pale yellow, without color pattern.
Prostomium (Fig.
Caruncle rectangular and conspicuous, medial lobe projecting above paired lateral lobes. Caruncle restrict to chaetiger 1, equal in length to posterior prostomial lobe of prostomium, reaching to anterior margin of chaetiger 2, arising medially and confluently with posterior prostomium (Fig.
All parapodia biramous, with chaetiger 1 greatly reduced, chaetiger 2 forming first dorsally complete ring. Parapodia with slender cirri (Fig.
Branchiae present from chaetiger 3, located on posterior face of each notopodia (Fig.
Notochaetae of three types: stout harpoon chaetae, numbering 13–24 per fascicle (Fig.
All specimens examined are incomplete lacking the posterior part. Specimen size varies from 1.9 to 2.5 mm in maximum width. Branchial chaetiger range varies from 3 to 31–40. The maximum number of branchial filaments varies from 20–29. One female paratype (MBM200143) with eggs in posterior coelomic cavity, ranging in diameter from 71μm to 90 μm.
The species is named after Beibuwan, the Chinese name for the Beibu Gulf (Tonkin Gulf), South China Sea.
Only known from Beibu Gulf, South China Sea.
Caruncle morphology appears to be an essential character which can be used to distinguish the species of
1 | Branchiae present from chaetiger 2 continuing to end of body |
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– | Branchiae present from chaetiger 3 or 4 |
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2 | Branchiae present from chaetiger 3 |
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– | Branchiae present from chaetiger 4 |
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3 | Eyes absent |
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– | Eyes present, one or two pairs |
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4 | Several pairs of branchiae until end of body |
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– | Only six pairs of branchiae |
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5 | First pair of eyes semicircular |
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– | First pair of eyes rounded |
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6 | Posterior margin of prostomium bilobed, more than 40 pairs of branchiae |
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– | Posterior margin of prostomium not bilobed, less than 40 pairs of branchiae |
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7 | Six pairs of branchiae, caruncle absent |
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– | About 23 pairs of branchiae, caruncle present, small and rounded |
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8 | Anterior lobe of prostomium conical, not expanded anteriorly |
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– | Anterior lobe of prostomium rounded, anteriorly expanded |
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9 | One pair eyes |
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– | Two pairs of eyes |
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10 | Caruncle present, cirri of second chaetiger longer than others |
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– | Caruncle absent, cirri of second chaetiger as long as others |
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11 | More than 20 pairs of branchiae present |
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– | Maximally 16 pairs of branchiae present |
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12 | Branchiae present only on anterior chaetigers, eyes indistinct |
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– | Branchiae present in all but first two and last few chaetigers, eyes distinct |
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13 | Caruncle absent, eyes inconspicuous |
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– | Caruncle present, eyes conspicuous |
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14 | 13-16 pairs of branchiae present, caruncle present |
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– | Maximally seven pairs of branchiae present, caruncle absent |
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15 | More than 40 pairs of branchiae present, eyes distinct, caruncle absent |
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– | Less than 10 pairs of branchiae, eyes absent, caruncle present |
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16 | Seven pairs of branchiae present, subdistally inflated (hastate) acicular chaetae absent |
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– | Less than 7 pairs of branchiae present, subdistally inflated (hastate) acicular chaetae present |
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17 | Five or six pairs of branchiae present, dorsal cirri absent in branchial chaetigers, caruncle in deep pocket at posterior margin of prostomium, small and rounded |
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– | Five pairs of branchiae present, dorsal cirri absent in branchial chaetigers, caruncle button-shaped |
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We appreciate the assistance of Dr. Sergio I. Salazar -Vallejo (EI Colegio de la Frontera Sur, Chetumal, Mexico) and Dr. Beatriz Yáñez-Rivera (Ciencias del Mar y Limnología, Universidad Nacional Autónoma de México, Unidad Académica Mazatlán, Mexico) for their kind help with our taxonomic research and for providing us with important references. We are grateful to Dr. Paulo Paiva and Dr. Jerry D. Kudenov for their comments and suggestions improving the manuscript. We are also grateful to the managers of the