Research Article |
Corresponding author: Zhao-Liang Guo ( zlguo@fosu.edu.cn ) Academic editor: Ingo S. Wehrtmann
© 2020 Qing-Hua Chen, Wen-Jian Chen, Xiao-Zhuang Zheng, Zhao-Liang Guo.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Chen Q-H, Chen W-J, Zheng X-Z, Guo Z-L (2020) Two freshwater shrimp species of the genus Caridina (Decapoda, Caridea, Atyidae) from Dawanshan Island, Guangdong, China, with the description of a new species. ZooKeys 923: 15-32. https://doi.org/10.3897/zookeys.923.48593
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A faunistic and ecological survey was conducted to document the diversity of freshwater atyid shrimps of Dawanshan Island. Two species of Caridina that occur on this island were documented and discussed. One of these, Caridina tetrazona sp. nov. is described and illustrated as new to science. It can be easily distinguished from its congeners based on a combination of characters, which includes a short rostrum, the shape of the endopod of the male first pleopod, the segmental ratios of antennular peduncle and third maxilliped, the slender scaphocerite, and the absence of a median projection on the posterior margin. Live individuals of the new species display a unique coloration pattern with four dark blue transverse bands on the body, and can be easily recognized in the field. So far, despite considerable surveying efforts made on neighboring islands, this species has only been found from a small stream on Dawanshan Island, which suggests that it may have a very limited range, probably endemic to Dawanshan Island. Molecular characteristics of the mitochondrial cytochrome c oxidase subunit I (COI) demonstrate that this species shows sufficient interspecific divergence from its congeners, including C. serrata Stimpson, 1860, which was found in four streams on Dawanshan Island, and has been previously reported on the neighboring islands of Hong Kong, Dong’ao, Wailingding, and Guishan.
COI, morphology, rice shrimp, systematics, taxonomy
The genus Caridina H. Milne Edwards, 1837, comprising 302 species and mainly present in the Indo-Pacific region, is the most diversified genus of the Atyidae (
The Wanshan Islands are located in the Pearl River Estuary, Zhuhai, Guangdong Province, southern China. Dawanshan Island (21°55'19.69" – 21°57'21.46"N, 113°42'54.30" – 113°45'06.09"E) covers an area of 8175 km2, and is situated in the south of the Wanshan Islands. It is about 29 km northwest from Macau, 33 km from Zhuhai City, and 56 km northeast from Hong Kong (Fig.
With an unspoiled natural landscape and an ideal climate, the island is promising for marine ecotourism development. The increasing exploitation of resources for tourism threatens the species that live there. The new species could be potentially seriously threatened and should be regarded as an endangered species.
Dawanshan Island (21°55'19.69" – 21°57'21.46"N, 113°42'54.30" – 113°45'06.09"E) belongs to the Wanshan Islands. It is a small island, 3.35 km in length, 2.45–3.88 km in width, with a coastline of 14.42 km, and five bays around the island. There are five peaks, with the highest point of Wanshan Peak in the central part of the north, at 432.5 m above sea level. Dawanshan Island has loess sandy soil over a rocky base. There are many cliffs on both sides of the south and west, and huge rocks on both sides of the east and north. The island has a subtropical oceanic monsoon climate, which is warm and humid throughout the year, with an average annual temperature of 22–23 °C, an average annual precipitation of 1800–2000 mm and an average annual relative humidity of 81.0%. Vegetation on Dawanshan Island is of evergreen broad-leaved forest type, with a forest coverage rate of about 60% (
Samples were collected by a hand net with a mesh size of 0.8 mm. All specimens obtained were fixed in 95% ethanol. The ethanol was changed after 24 hours with fresh 75% ethanol. The drawings were made with the aid of a drawing tube mounted on an Olympus BX – 41 compound microscope.
The forward and reverse primers of the mitochondrial COI gene in this study were: LCO1490 and HCO2198, respectively (
A total of 26 nucleotide sequences were analyzed. Selected species for the molecular analyses were species similar to the morphology and the color of the new species and the Caridina species that are known to occur on neighbouring islands. All the sequences were aligned with MAFFT v7.313 software using the auto strategy and normal alignment mode (
Specimens of the atyids Caridina and Neocaridina used in the molecular analyses (new sequences), listed by localities, geographical coordinates and GenBank accession numbers.
Species | Locality | Geographical coordinates | Accession no. |
---|---|---|---|
C. cantonensis | Wutong Mountain, Shenzhen | 22°34'49"N, 114°12'44"E | MN701589 |
Wutong Mountain, Shenzhen | 22°34'49"N, 114°12'44"E | MN701590 | |
Baiyun Mountain, Guangzhou | 23°10'05"N, 113°17'36"E | MN701591 | |
Baiyun Mountain, Guangzhou | 23°10'05"N, 113°17'36"E | MN701592 | |
C. huananensis | Yingde, Qingyuan | 23°54'17"N, 113°15'55"E | MN701607 |
Yingde, Qingyuan | 23°54'17"N, 113°15'55"E | MN701608 | |
C. lanceifrons | Dongfang, Hainan | 18°40'06"N, 109°56'32"E | MN701605 |
Dongfang, Hainan | 18°40'06"N, 109°56'32"E | MN701606 | |
C. mariae | Nankun Mountain, Huizhou | 23°39'32"N, 113°54'19"E | MN701601 |
Nankun Mountain, Huizhou | 23°39'32"N, 113°54'19"E | MN701602 | |
C. serrata | Dawanshan Island, Zhuhai | 21°33'41"N, 113°25'59"E | MN701595 |
Dawanshan Island, Zhuhai | 21°33'41"N, 113°25'59"E | MN701596 | |
Dong’ao Island, Zhuhai | 22°00'17"N, 113°25'27"E | MN701599 | |
Dong’ao Island, Zhuhai | 22°00'17"N, 113°25'27"E | MN701600 | |
C. tetrazona sp. nov. | Dawanshan Island, Zhuhai | 21°33'57"N, 113°25'48"E | MN701593 |
Dawanshan Island, Zhuhai | 21°33'57"N, 113°25'48"E | MN701594 | |
C. zhujiangensis | Dong’ao Island, Zhuhai | 22°00'38"N, 113°25'13"E | MN701603 |
Dong’ao Island, Foshan | 22°00'38"N, 113°25'13"E | MN701604 | |
N. palmata | Yangshan, Qingyuan | 24°25'28"N, 112°36'28"E | MN701609 |
Yangshan, Qingyuan | 24°25'28"N, 112°36'28"E | MN701610 | |
N. hofendopoda | Sanxia, Yichang | 30°49'32"N, 111°00'59"E | MN701611 |
Sanxia, Yichang | 30°49'32"N, 111°00'59"E | MN701612 |
The following abbreviations are used throughout the text: al: altitude; cl: carapace length (measured from the postorbital margin to the posterior margin of the carapace); coll: sample collectors; rl: rostral length (measured from the rostral tip to the postorbital margin); stn: sampling station; tl: total length (measured from the rostral tip to the posterior margin of the telson). All measurements are in millimeters.
Specimens were deposited in the Department of Animal Science, School of Life Science and Engineering, Foshan University (FU).
Subfamily Atyinae De Haan, 1849
Genus Caridina H. Milne Edwards, 1837
Caridina serrata Stimpson, 1860: 29 [type locality: Hong Kong, China].
Caridina serrata
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13 females, cl 3.5–6.8 mm, 2 ovigerous cl 3.7–5.6 mm, 5 males cl 3.0–5.8 mm, a small pool (21°56'48.6"N, 113°42'55.5"E, al. 5.4 m, stn 2), 27 June 2017, coll. Z. L. Guo, W. J. Chen; 17 females, cl 3.4–6.6 mm, 2 ovigerous females, cl 4.1–5.6 mm, 15 males, cl 2.9–5.5 mm, a small stream (21°56'43.6"N, 113°42'51.4"E, al. 27.2 m, stn 3), 27 June 2017, coll. Z. L. Guo, W. J. Chen; 5 females, cl 3.1–6.9 mm, 3 ovigerous, cl 3.5–5.8 mm, 3 males, cl 3.0–5.2 mm, a small stream (21°56'15.6"N, 113°43'33.4"E, al. 186.6 m, stn 4), 28 June 2017, coll. Z. L. Guo, W. J. Chen; 7 females, cl 3.4–6.9 mm, 4 males, cl 3.5–5.7 mm, a small stream (21°56'02.8"N, 113°43'29.0"E, al. 122.8 m, stn 5), 28 June 2017, coll. Z. L. Guo, W. J. Chen.
The present specimens are in agreement with the description and illustrations of
Caridina serrata is commonly found in pools, streams, and artificial ditches on the island. Sometimes, the stream connects with the sea. Sediment at the site comprised sand, pebbles and gravel patches between large boulders. Hill streams are within secondary forests and are covered with aquatic plant (Fig.
The live shrimp show light-red coloration and are translucent (Fig.
Holotype : male (FU, 2017-06-27-01), cl 3.9 mm, tl 14.4 mm, rl 1.3 mm, a stream near Longtangzui Dawanshan Island, Zhuhai City, Guangdong, China (21°56'59.2"N, 113°43'00"E, al. 8 m, stn 1), 9 June 2017. Paratypes: male (FU, 2017-06-27-02), cl 4.3 mm, 4 males (FU, 2017-06-27-03), cl 3.8–4.3 mm, 33 females, 4 ovigerous (FU, 2017-06-27-04), cl 3.8–5.4 mm, same collection data as for holotype, coll. Z. L. Guo, W. J. Chen.
Caridina serrata Stimpson, 1860 (see material under Caridina serrata). Caridina cantonensis Yu, 1938; 8 males, cl 3.5–6.3 mm, 5 females, 2 ovigerous, cl 4.1–6.3 mm, a stream at Mangzixia, Yingde, Qingyuan City, Guangdong, China (24°3'20"N, 113°19'6"E, al. 20 m), 4 June 2018, coll. Z. L. GUO, W. J. Chen, X. Z. Zheng.
Rostrum short, straight or slightly sloping downwards, nearly reaching to or slightly reaching beyond end of 1st segment of antennular peduncle, rostral formula 3–8 (usually 5–7) + 4–6/1–2. 1st pereiopod carpus 0.63–0.70 × as long as chela, 1.6–1.7 × as long as high; chela 1.8–2.0 × as long as broad; fingers 0.92–1.1 × as long as palm. 2nd pereiopod carpus 1.1–1.3 × as long as chela, 4.9–5.3 × as long as high; chela 2.7–2.9 × as long as broad; fingers 1.7–1.8 × as long as palm. 3rd pereiopod propodus 3.9–4.5× as long as dactylus, with 8–11 thin spines on the posterior and lateral margins. 5th pereiopod propodus 4.9–5.1 × as long as dactylus, with 8–11 thin spines on the posterior and lateral margins, dactylus terminating in one claw, with 27–31 spinules on flexor margin. Endopod of male 1st pleopod extending to 0.56 × exopod length, wider proximally, subrectangular, 2.5–2.6 × as long as wide, appendix interna well developed, arising from distal 1/3 of endopod, reaching beyond end of endopod. Appendix masculina of male 2nd pleopod rod-shaped, reaching to 0.7 length of endopod, appendix interna reaching to 0.7 length of appendix masculina. Uropodal diaeresis with 18–20 movable spinules. Eggs 0.51–0.65 × 0.84–0.97 mm in diameter.
Body: small, slender and sub-cylindrical, males up to 14.8 mm tl, females up to 20.4 mm tl.
Rostrum (Fig.
Eyes (Fig.
Carapace (Fig.
Antennule (Fig.
Antenna (Fig.
Mandible (Fig.
Maxillula (Fig.
Maxilla (Fig.
First maxilliped (Fig.
Second maxilliped (Fig.
Branchial formula typical for genus. Epipod on first four pereiopods.
Third maxilliped (Fig.
First pereiopod (Fig.
Second pereiopod (Fig.
Third pereiopod (Fig.
Fourth pereiopod: Reaches middle of 2nd segment of antennular peduncle; dactylus 3.0–4.2 × as long as wide, ending in prominent claw-like spine surrounded by simple setae, flexor margin bearing 4–6 spines; propodus 4.2–5.1 × as long as dactylus, bearing 9–13 spinules on posterior and lateral margin, 8.5–10.5 × as long as wide; carpus 0.66–0.81 × as long as propodus; merus 1.6–1.8× as long as carpus, with about 3–4 strong spines on the posterior margin.
Fifth pereiopod (Fig.
First pleopod (Fig.
Second pleopod (Fig.
Telson (Fig.
Eggs 0.51–0.65 × 0.84–0.97 mm in diameter.
Coloration: Body semi-translucent, four dark blue bands transverse on the tergum of the 1st, 3rd, 5th, and 6th abdominal segments, appendages mostly translucent (Fig.
Caridina tetrazona is a combination of two Latin words, tetra, four, and zona, band, alluding to its four-banded color pattern.
Caridina tetrazona sp. nov. is most similar to C. serrata Stimpson, 1860 (which also occurs on the same island) in the short rostrum, the shape of the endopod of the male first pleopod, and the similar-sized eggs. It can be easily distinguished from C. serrata by the length of the basal segment of the antennular peduncle which is as long as the combined length of 2nd and 3rd segments (versus length of basal segment distinctly longer than the combined length of 2nd and 3rd segments in C. serrata); length of penultimate segment of 3rd maxilliped as long as basal segment; the distal segment is distinctly shorter than the penultimate segment (versus penultimate segment distinct shorter than basal segment and distal segment as long as penultimate segment in C. serrata); the absence of a projection on the posterior margin of telson (versus with a projection in C. serrata), and the slender scaphocerite (3.6–3.7 times as long as wide versus 3.0–3.2 times in C. serrata). In addition, the four dark blue bands on the body of live shrimps allow an easy identification in the field. Caridina tetrazona sp. nov. also shows close similarity with C. cantonensis Yu, 1938 regarding the ratios of various segments of the 1st and 2nd pereiopods. Beside its peculiar coloration, C. tetrazona sp. nov. differs from C. cantonensis in the short rostrum, which only reaches the end of 1st segment of the antennular peduncle (versus distinctly reaches beyond the end of the 2nd segment in C. cantonensis); the endopod of the male first pleopod slender (2.6–2.7 times as long as wide versus 2.1–2.4 times in C. cantonensis) and distal part not dilated (versus distally distinctively dilated in C. cantonensis); palp of 1st maxilliped ending in a finger-like tip (versus broadly rounded in C. cantonensis); and absence of a projection on the posterior telsonic margin (versus with a projection in C. cantonensis). Caridina tetrazona sp. nov. closely resembles C. trifasciata Yam & Cai, 2003, in having similar dark blue bands on their abdomen, and in having the shape of the endopod of the male 1st pleopod and appendix masculina of the male 2nd pleopod similar. Caridina tetrazona sp. nov. differs from C. trifasciata in its proportionately shorter rostrum (only reaches the end of the 1st segment of the antennular peduncle versus reaches beyond the end of the 2nd segment in C. trifasciata); palp of the 1st maxilliped ending in a finger-like tip (versus broadly rounded in C. trifasciata); and the slender scaphocerite (3.6–3.7 times as long as wide versus 2.8 times in C. trifasciata).
The type specimens were collected from a small stream at an elevation of 8 m, stn 1, near Longtangzui, Dawanshan Island, Zhuhai City, Guangdong, China (21°56'59.2"N, 113°43'00"E) (Fig.
only known from Guangdong Province, southern China.
The primers used in this study are located at the 5’ end of the COI gene, and the new sequencing results are corrected for 624~bp for subsequent analysis. As can be seen from Table
Pairwise genetic distance among eight Caridina species (Atyidae) based on the COI gene. The range of genetic distances between different species is in parentheses.
Species | 1 | 2 | 3 | 4 | 5 | 6 | 7 |
---|---|---|---|---|---|---|---|
1. C. cantonensis | |||||||
2. C. huananensis | 0.189 (0.171–0.207) | ||||||
3. C. lanceifrons | 0.234 (0.221–0.246) | 0.246 (0.245–0.246) | |||||
4. C. mariae | 0.110 (0.100–0.119) | 0.216 (0.215–0.216) | 0.277 (0.277–0.277) | ||||
5. C. serrata | 0.149 (0.139–0.159) | 0.240 (0.224–0.255) | 0.260 (0.252–0.268) | 0.144 (0.137–0.150) | |||
6. C. tetrazona sp. nov. | 0.128 (0.118–0.138) | 0.203 (0.199–0.206) | 0.227 (0.227–0.227) | 0.137 (0.137–0.137) | 0.067 (0.033–0.101) | ||
7. C. trifasciata | 0.112 (0.105–0.118) | 0.214 (0.206–0.221) | 0.256 (0.252–0.260) | 0.147 (0.144–0.150) | 0.117 (0.100–0.134) | 0.091 (0.088–0.094) | |
8. C. zhujiangensis | 0.237 (0.229–0.244) | 0.325 (0.321–0.329) | 0.265 (0.265–0.265) | 0.281 (0.281–0.281) | 0.291 (0.279–0.303) | 0.263 (0.263–0.263) | 0.241 (0.237–0.245) |
The faunistic and ecological results of the present survey illustrate that the freshwater atyid shrimps are not very diverse along the habitats of the coastline of Dawansha Island; only two species of Caridina occur on this island. Caridina tetrazona is a new species, while Caridina serrata Stimpson, 1860 is known from a wide area and can be commonly found in streams from this island. In addition, it also occurs on neighboring islands, i.e., Hong Kong, Dong’ao Island, Wailingding Island, and Guishan Island (
According to the COI sequence, the range of interspecific genetic divergence (K2P) between Caridina tetrazona sp. nov. and the other seven species of Caridina was 6.7–32.5%. This result is in accordance with the minimum interspecific genetic distance of 2% recommended by
As these isolated and vicariant atyid shrimps occur in tightly constrained coastal locations, they may be particularly vulnerable to anthropogenic changes. The island has high potential for ecotourism due to its unspoilt natural landscape and ideal climate. The increase in tourism poses a threat to the survival of this species. Moreover, Caridina tetrazona sp. nov. displays a striking coloration pattern, which will certainly receive particular attention among aquarists, so the possible threat by over-harvesting is also present. A program should be developed to guide and control ecological tourism on the island. Monitoring changes in wild populations according to local legislation should also be intensified, and campaigns that promote environmental education and raising tourists’ awareness of the importance of biodiversity should be encouraged.
This study was supported by the Special Fund for Central Public Welfare Research Institutes (Grant No. PM-zx097-201904-134), the Running Cost for Key Laboratory of Utilization and Breeding of Aquatic Resources in Tropical and Subtropical Areas, Ministry of Agriculture and Rural Affairs (Grant No. 9020190008) and the Investigation on Crustaceans in Priority Area of Mangrove Diversity Protection in Guangxi Zhuang Autonomous Region (Grant No. kh19051). We thank Dr. Chao Huang (University of New South Wales) for modifying the manuscript. Thanks are also due to subject editor Ingo Wehrtmann, copy editor Christopher Glasby and two reviewers (Yixiong Cai and Charles Fransen) for providing their valuable suggestions, which greatly improved the manuscript.