Corresponding author: Hongzhu Wang (
Academic editor: R. Blakemore
Three new species of
The existence of unique faunae in ancient lakes of Yunnan Province, Southwest China has been recognized in several studies (
Being the deepest lake on the Yunnan-Guizhou Plateau, the Fuxian Lake (24°17'–37'N, 102°49'–57'E) is located in the eastern part of Yunnan Province, and it discharges into the upper reaches of Nanpanjiang River. The lake covers an area of 211 km2 at its surface water-level of 1721 m ASL, attaining a maximum depth of 155 m and a shoreline development (D
Lake sediment samples were collected with a weighted Petersen grab (1/16 m2) and cleaned with a 250 µm sieve. Large worms were manually sorted in a white porcelain dish and small ones were sorted under a dissecting microscope. Specimens were all preserved in 10% formalin.
Preserved specimens were examined first in temporary glycerine mounts, then stained with borax carmine, dehydrated in an alcohol series, cleared in xylene and mounted in Canada balsam. Measurements of body and chaeta were made from the glycerine mounts. Other observations were made on the permanent mounts. Drawings were made using a camera lucida. Types and other specimens were deposited in Institute of Hydrobiology (IHB), Chinese Academy of Sciences (CAS), Wuhan, China.
Roman numerals = segment number; at = atrium; mu = muscle; pc = penial chaeta; pe = penis; pr = prostate gland; ps = penial sac; sa = spermathecal ampulla; sc = spermathecal chaeta; scs = spermathecal chaeta sac; sd = spermathecal duct; sf = sperm funnel; sz = spermatozeugmata; vd = vas deferens.
Hair chaetae present or absent, dorsal chaetae bifid and always pectinated, or only bifids. Ventral chaetae bifids. No coelomocytes. Vas deferens very short, entering atrium apically; atrium tubular, long. Prostate gland small, attached to proximal part of atrium by a short stalk, or no prostate gland. No ejaculatory duct. Penis with or without cuticular sheath. Spermatozeugmata present. Modified spermathecal chaetae present or absent.
The genus
Principal distinguishing characteristics of the species of
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1 | present | pectinated | present | absent or unmodified | 1:33–35 | present | tripartite | present | Russia |
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2 | present | pectinated | present | unmodified | 1:8–9 | absent | tripartite | present | Holarctic, Australia, New Zealand | ||
3 | present | pectinated | present | unmodified | 1:25–30 | absent | tripartite | present | Europe, North America, China | ||
4 | absent | bifid | absent, or 2–3 bifids | absent or unmodified | 1:22–26 | present | bipartite | present | Russia |
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5 | absent | bifid | absent, or 4–5 bifids | unmodified | 1:28–31 | absent | bipartite | present | Caspian Sea |
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6 | absent | bifid | present | absent or unmodified | 1:15–17 | present | bipartite | present | Russia |
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7 | present | pectinated | present | absent or unmodified | 1:40–45 | present | bipartite | present | Holarctic |
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8 | present | pectinated | present | unmodified | 1:20 | absent | tripartite | present | Europe, Israel | ||
9 | absent | bifid | present | - | - | present | - | present | Europe |
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10 | absent | bifid | present | unmodified | 1:14–17 | absent | bipartite | present | Caspian Sea |
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11 | absent | bifid | absent, or 1–2 bifids | absent or unmodified | 1:22–24 | present | bipartite | present | Russia, Czech | ||
12 | absent | bifid | present | unmodified | 1:20–32 | absent | tripartite | present | Holarctic | ||
13 | present | bifid | absent | unmodified | - | present | - | present | North America, Serbia |
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14 | present | bifid | present | - | - | absent | - | - | North America |
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15 | present | pectinated | absent | - | - | present | homo-geneous | - | Slovenia |
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16 | present | bifid | present | - | - | absent | - | present | Serbia |
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17 | present | bifid | present | - | - | present | - | - | Europe, Russia |
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18 | present | pectinated | present | unmodified | 1:20 | present | tripartite | present | Romania |
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19 | present | pectinated | present | - | 1:34 | absent | homo-geneous | present | Africa |
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20 | present | bifid | present | absent or unmodified | 1:30–33 | present | bipartite | present | Europe, North America |
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“-”Unmentioned in the original descriptions
IHB YAN 20021205b, mature specimen mounted in Canada balsam, and stained with borax carmine.
East of Lichang (
“
One complete specimen 7.6 mm long, diameter at XI about 0.8 mm, 27 segments. Prostomium conical. Clitellum inconspicuous.
Dorsal chaetae (
Pharyngeal glands in II–III. Chloragogen cells from VI onwards. No coelomocytes. Male genitalia (
Spermathecae (
Known only from its type locality, Yunnan Province, China; freshwater lake, 113 m depth, water temperature less than 14 °C, fine clay.
According to short vasa deferentia, long tubular atria, each with a small prostate gland, and lack of ejaculatory ducts, the new species fits more closely the definition of
IHB YAN 20020812i, mature specimen mounted in Canada balsam, and stained with borax carmine.
East of Gushan Island (
Named “
Specimen incomplete, length > 4.4 mm, diameter at XI about 0.7 mm, segments > 13. Clitellum inconspicuous.
Chaetae (
Pharyngeal glands in II–III. Chloragogen cells from VI onwards. No coelomocytes. Male genitalia (
Spermathecae ducts (
Known only from its type locality, Yunnan Province, China; freshwater lake, 78 m depth, water temperature less than 16 °C, fine clay.
According to very short vasa deferentia, long tubular atria each with a small prostate gland, and lack of ejaculatory ducts, the new species fits more closely the definition of
This new speciesresembles
The new species is distinguishable from other species from the Yunnan lakes in the characteristics of some somatic chaetae. For instance, hair chaetae and pectinate bifid chaetae are present in
Comparison of six species of
Species | ||||||
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Hair chaetae | forward VII, plumose | forward III or V, plumose | absent | forward V, plumose | forward II, smooth | forward VI, plumose |
Pectinate bifid chaetae | associated with hairs | associated with hairs | absent | associated with hairs | present | associated with hairs |
Ventral chaetae | bifid | bifid | bifid | bifid, lower prong usually secondarily branched | bifid | bifid, lower prong usually secondarily branched |
Spermathecal chaetae | ||||||
Penial chaetae | absent | absent | present | absent | absent | present |
Length ration of vd/at | 1:12-16 | 1:11-20 | 1:30-42 | 1:10-18 | 1:14-30 | 1:3 |
Prostate glands | present | absent | present | present | absent | absent |
Male ducts | homogenous | homogenous | homogenous | homogenous | bipartite | homogenous |
Penial sheath | absent | absent | absent | absent | absent | present |
Habitats | Freshwater lake, 70-110 m depth, <15°C, fine clay | Freshwater lake, 70-120 m depth, <15 °C, fine clay. | Freshwater lake, 78 m depth, <16°C, fine clay | Freshwater lake, 113 m depth, < 14°C, fine clay | Freshwater lake, 5 m depth, 18°C, mud | Freshwater lake, 74 m depth, <15°C, fine clay |
IHB YAN 20021205c, mature specimen mounted in Canada balsam, and stained with borax carmine.
IHB YAN20021205c, East of Lichang (
IHB YAN20021012b, East of Gushan Island (
Named “
Two complete specimen 8.9–19.8 mm long (Holotype: 8.9 mm), with 36–131 segments (Holotype: 36), diameter at XI about 0.8 mm. Prostomium conical. Clitellum inconspicuous.
Dorsal chaetae (
Pharyngeal glands in II. Chloragogen cells from IV or V onwards. No coelomocytes. Male genitalia (
Spermathecae (
Known only from its type locality, Yunnan Province, China; freshwater lake, 70–110 m depth, water temperature less than 15 °C, fine clay.
According to short vasa deferentia, long tubular atria and lack of ejaculatory ducts, the new species fits more closely the definition of
The new speciesresembles
The new species are distinguishable from other species from Yunnan Lakes in that of the position of their reproductive organs and the characteristic of some somatic chaetae. For instance, the reproductive organs are move to VIII–X in
The principal distinguishable characteristics of the species of
In the genus of
In addition, the presence of pectinate bifid chaetae accompanied with hair chaetae in the Yunnan lake species could be a special feature, but their position is variable. For instance, the hairs and pectinate bifids begin from segments V, VI, VII, III or V, respectively in
As for habitat and distribution, the five species of
Lastly, according to some specific features, such as hair and pectinate bifid chaetae, spermathecal pore position, atrium histological structure, and their habitat, the species from Yunnan lakes maybe one new taxonomical group, the systematic placement of which needs further confirmation from more work.
1 | Prostate glands present | 2 |
– | Prostate glands absent | 15 |
2 | Hair chaetae present | 3 |
– | Hair chaetae absent | 11 |
3 | With plumose hair chaetae | 4 |
– | Without plumose hair chaetae | 5 |
4 | Prostate glands small, proximally attached to atria | |
– | Prostate glands small, proximally attached to atria and far from vasa deferentia | |
5 | Dorsal bifid chaetae pectinated | 6 |
– | Dorsal chaetae bifid | 9 |
6 | Spermathecal chaetae present | 7 |
– | Spermathecal chaetae absent | |
7 | Histological atria tripartite | 8 |
– | Histological atria bipartite | |
8 | Length ratio of vasa deferentia to atria about 1:33–35 | |
– | Length ratio of vasa deferentia to atria about 1:20 | |
9 | Spermathecal chaetae present and modified | 10 |
– | Spermathecal chaetae absent or 1–2 bifid chaetae | |
10 | Upper tooth of ventral chaetae just shorter or equal the lower | |
– | Upper tooth of ventral chaetae reduced | |
11 | Spermathecal chaetae present and modified | 12 |
– | Spermathecal chaetae absent or 1–3 bifid chaetae | 14 |
12 | Penes present | 13 |
– | Penes absent | |
13 | Ventral chaetae 5–6 per bundle | |
– | Ventral chaetae 8–10 per bundle | |
14 | Upper tooth of bifid chaetae longer and thinner than the lower | |
– | Upper tooth of bifid chaetae equal the lower | |
15 | Hair chaetae present | 16 |
– | Hair chaetae absent | 23 |
16 | With plumose hair chaetae | 17 |
– | Without plumose hair chaetae | 18 |
17 | Male genitalia in X–XI, with penial sheath | |
– | Male genitalia in VIII–IX, without penial sheath | |
18 | Dorsal bifid chaetae pectinated | 20 |
– | Dorsal chaetae bifid | 9 |
19 | Upper tooth of ventral chaetae slightly longer and thinner than the lower | |
– | Tooth of ventral chaetae equal in length | |
20 | Histological atria homogeneous | |
– | Histological atria bipartite | |
– | Histological atria tripartite | 21 |
21 | Male genitalia in X–XI | 22 |
– | Male genitalia in VIII–IX | |
22 | Length ratio of vasa deferentia to atria about 1:20 | |
– | Length ratio of vasa deferentia to atria about 1:8–9 | |
23 | Spermathecal chaetae present and modified | 24 |
– | Spermathecal chaetae absent or 4–5 bifid chaetae | |
24 | Histological atria bipartite | |
– | Histological atria tripartite |
We are indebted to Dr. Xueqin Liu, Dr. Jianhui Qin and Dr. Sixin Li (Institute of Hydrobiology, Chinese Academy of Sciences) for their kind assistance in the field work. We also want to especially thank Prof. Yanling Liang (Institute of Hydrobiology, Chinese Academy of Sciences), Prof. Tarmo Timm (Centre for Limnology, Tartumaa, Estonia), Dr. Patrick Martin (Royal Belgian Institute of Natural Sciences) and Dr. Mark J. Wetzel (Illinois Natural History Survey) for their inspiring comments on the manuscript. The financial support was provided by the National Natural Science Foundation of China (No. 30470205) and the Knowledge Innovation Program of the Chinese Academy of Sciences.