中国枝角类低额溞属一新记录
——密刺低额溞Simocephalus congener (Koch, 1841)

舒树森陈非洲杨君兴陈小勇

(1. 中国科学院昆明动物研究所, 遗传资源与进化国家重点实验室, 昆明 650223; 2. 中国科学院南京地理与湖泊研究所,湖泊与环境国家重点实验室, 南京 210008)

中国枝角类低额溞属一新记录
——密刺低额溞Simocephalus congener (Koch, 1841)

舒树森1陈非洲2杨君兴1陈小勇1

(1. 中国科学院昆明动物研究所, 遗传资源与进化国家重点实验室, 昆明 650223; 2. 中国科学院南京地理与湖泊研究所,湖泊与环境国家重点实验室, 南京 210008)

密刺低额 溞; 枝角类; 中国; 尾爪; 第二胸足

The genus Simocephalus Schoedler 1858, a large, nonpelagic daphniidae, are abundant in the littoral zone, expecially with submerged aquatic vegetation in freshwater bodies all over the world. More than 63 specific and subspecific names have been proposed. But in the recent research, all of them were divided into 4 subgenus and regarded as 20 valid names[1]. More than 12 species of genus Simocephalus were recorded in China[2—5], and most of them need to be re-examined according to modern standards.

The valid of Simocephalus congener was controversial. Most authors suppose S. congener to be a synonym of S. exspinosus or a variety in the last century[1]. Nowadays, S. congener has been regarded as a valid species because there is a morphological hiatus between S. exspinosus and S. congener in the number and size of spines on the postabdominal claw[1], and this view was accepted by more and more researchers[6, 7].

In a survey of the zooplankton diversity in Shangri-la County, Yunnan Province, China, some specimens of S. congener were collected from small ponds in Potatso National Park. The details of morphology including limbs were described here and contributed to the validity of the S. congener, which is also the first record in China.

1 Materials and methods

Fourteen parthenogenetic female were collected from a pond (27°52.136 N 99°56.163 E) in Potatso National Park, 20 August 2011. Altitude 3519 m; water temperature 16.4°C; pH 8.76; conductivity 110 μS/cm; All specimens are deposited in the Kunming Institute of Zoology (KIZ), Chinese Academy of Sciences (CAS).

The sampled specimens were examined and dissected under a Leica S6D stereo microscope and then observed and drawn using a Leica DM2500 compound microscope after mounting on slides. Identifications and morphological terminology follows Orlova-Bienkowskaja[1].

2 Result

Simocephalus congener (Koch, 1841)

Daphnia congener Koch, 1841: 35;

Simocephalus congener: Schoedler, 1858:20; Sramek- Husek et al., 1962:265; Orlova-Bienkowskaja, 1998: 25—26, Fig. 34; Orlova-Bienkowskaja 2001: 78—80, Fig. 51—57, 114—115,P6: Fig. 30; Kotov et al. 2011: 405; Kotov et al. 2012: 58—60, Fig. 6; Sinev & Korovchinsky, 2013: 129, Fig. 2F,2G; S. exspinosus var. congener: Lilljeborg, 1900: 177; S. exspinosus: Sars, 1888; Floessner, 1972: 184.

Type locality.It was not indicated in the original description, but probably in Germany[1].

Localities in China.(1) Yunnan Province: Shangrila County: Potatso National Park.

(2) Heilongjiang Province: Harbin City; Daqing City; Zalong County; Lindian County[3].

Parthenogenetic female.Body length from 1.6 to 2.2 mm (n=14), subovoid (Fig. 1A); Head round, with a small rostrum; ventral margin straight; large compound eye occupies antero-ventral portion of head; ocellus small, of irregular shape. Labrum with setulated distal labral plate, the figures were described by Kotov[6]. Valve convex, with a row of numerous setae submarginally near ventral margin; the anterior and posterior portion of setae shorter and stouter. Posterior margin straight, dorsal margin with a shallow cervical incision, the length of poster-dorsal vavle angle nearly none. Postabdomen (Fig. 1G) with prominent supra-anal angle, covering minute setules; preanal margin undulated, with a series of strongly, single anal teeth, the distal teeth largest and with setules. Abdominal process small. Postabdominal claw long, slightly curved, with about 10 small, thin teeth in proximal, more than 20 thin spines in basal pecten, and numerous fine setules in middle and frontal pecten (Fig. 1H). Antenna I tubular and short, with nine seathetes at end and one proximally implanted antennular sensory papilla. Antenna II short, the ends of the distal segment is not reached the middle of the valves. The antennal formula: setae 0-0-1-3/1-1-3, and a small spine on proximal segment as illustrated by Kotov[6]. Thoracic limb I-V typical of genus Simocephalus , with full complement of setae and spines (Fig. 1B-F). The second and third prominences of limb II with one seta each, and the length of the former is about 4 times than later.

Male:Unknown.

Additional Morphological Characters:The length of the second prominence’s seta is 4 times than the third’s in limb . Ⅱ

3 Remarks

The original description of S. congener was insufficient[1], and it was distinguished from S. exspinosus by the number of basal pectin of the postabdominal claw[8]. The length of seta in the second and third prominences of limb II was regarded as a diagnostic character[9], but the detail description and figures of S. congener are lack, although this species is found in many new locations[6, 7]. We confirmed that the ration of seta in limb II’s second and third prominences is 4 times in S. congener, and the ratio of S. exspinosus is 2 times[1, 10]. It is a useful character to identify S. congener from S. exspinosus.

S. congener was regarded as a synonym of S. exspinosus or a variety in the last century, and S. exspinosus was recorded in China and described as the basal spectin of the postabdominal claw is about 12[2], which ensures the species recorded in China is S. exspinosus. So this is the first record of S. congener in China.

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Fig. 1 Simocephalus congener (Koch, 1841), parthenogenetic femaleA. lateral view; B-F. limb I-V; G. postabdomen; H. postabdominal claw. Scale bars: 0.1 mm

S. himalayensis microdu Chen, Shi & Shi was reported in Heilongjiang Province, China, the original description is briefly, the characters that used by Chen et al.[3]to define S. himalayensis microdu are all included in the variability of S. exspinosus[1], it indicate the species of S. himalayensis microdu is very similar with S. exspinosus. But in the original description of S. himalayensis microdu, the spines of basal pecten in postabdominal claw is 9—20 in female and about 20 in male, this character cross the boundaries from S. exspinosus to S. congener. We therefore conclude that S. himalayensis microdu is a complex species of S. exspinosus and S. congener.

S. congener occurs with certainty in Central and Easter Europe and Siberia[1,10]. In recent years, this species was recorded in Korea[6]and South Vietnam[7], and now it is also recorded in China. The distribution of this species is enlarged and needed to be redefined after more research.

Acknowledgements:

We are grateful to Dr. Wangsheng Jiang and Yapeng Zhao for assistance with collecting the material.

References:

[1] Orlova-Bienkowskaja M Y. Daphniidae: genus Simocephalus. Guides to the identification of the microinvertebrates of the continental waters of the World, Vol. 17, Leiden: Backhuys publishers. 2001, 1—130

[2] Jiang S C, Du N S. Fauna Sinica: Crustacean – Freshwater Cladocera [M]. Beijing: Science Press. 1979, 124—130 [蒋燮治, 堵南山. 中国动物志: 节肢动物门–甲壳纲–淡水枝角类. 北京: 科学出版社. 1979, 124—130]

[3] Chen S Z, Shi X L, Shi X B. Description of a new subspecies of Simocephalus himalayensis Chiang et Chien, 1974 [J]. Natural Sciences Journal of Harbin Normal University, 1992, 8(1): 91—95 [陈受忠, 施心路, 史新柏. 喜马拉雅低额溞一新亚种(甲壳纲: 双甲目). 哈尔滨师范大学自然科学学报, 1992, 8(1): 91—95]

[4] Shi X L, Shi X B. On two new species and two new records of Simocephalus from China (Crustacea: Diaplostraca: Daphniidae) [J]. Acta Zootaxonomica Sinica, 1994, 19(4): 403—411 [施心路, 史新柏. 中国低额溞 属二新种及二新记录(甲壳纲: 双甲目: 溞属). 动物分类学报, 1994, 19(4): 403—411]

[5] Xu Y Q, Chen Y S, Lin G, et al. A new subspecies of Simocephalus latirostris [J]. Journal of Fujian Teachers University (Natural Science), 2002, 18(3): 66—68 [许友勤, 陈寅山, 林岗, 等. 宽吻低额溞 一新亚种. 福建师范大学学报, 2002, 18(3): 66—68]

[6] Kotov A A, Jeong H G, Lee W. Cladocera (Crustacea: Branchiopoda) of the south-east of the Korean Peninsula, with twenty new records for Korea [J]. Zootaxa, 2012, 3368: 50—90

[7] Sinev A Y, Korovchinsky N M. Cladocera (Crustacea: Branchiopoda) of Cat Tien National Park, South Vietnam [J]. Journal of Limnology, 2013, 72(s2): 125—141

[8] Lilljeborg W. Cladocera sueciae [J]. Nova Acta regiae Society Scientiarum Upsalensis, 1900, 19: 1—701

[9] Smirnov N N. Morpho-functional grounds of mode of life of Cladocera. V. Morphology and adaptive modifications of trunk limbs of Anomopoda [J]. Hydrabiologia, 1971, 37: 317—345

[10] Orlova-Bienkowskaja M Y. A revision of the cladoceran genus Simocephalus (Crustacea, Daphniidae) [J]. Bulletin of the Natural History Museum of London, Zoology, 1998, 64: 1—62

THE FIRST RECORD OF SIMOCEPHALUS CONGENER (KOCH, 1841) IN CHINA (CRUSTACEAN, DIPLOSTRACA, DAPHNIIDAE)

SHU Shu-Sen1, CHEN Fei-Zhou2, YANG Jun-Xing1and CHEN Xiao-Yong1
(1. State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming 650223, China; 2. State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China)

Simocephalus congener; Cladocera; China; Postabdominal claw; Limb Ⅱ

Yang Jun-Xing, E-mail: yangjx@mail.kiz.ac.cn; Chen Xiao-Yong, E-mail: chenxy@mail.kiz.ac.cn

Q959.22

A

1000-3207(2015)04-0850-03

10.7541/2015.112

Received date: 2014-08-07; Accepted date: 2015-01-24

Foundation item: Yunnan Provincial Science and Technology Program (2014FB178); National Key Technology R & D Program of

China (2008BAC39B03)

Brief introduction of author: Shu Shu-sen, male, Master; Engaged in freshwater crustacean taxonomy and ecology research. E-mail:

shuss@mail.kiz.ac.cn