Research Article |
Corresponding author: Hongying Sun ( sunhongying@njnu.edu.cn ) Academic editor: Kay Van Damme
© 2020 Zewei Zhang, Da Pan, Xiyang Hao, Hongying Sun.
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:
Zhang Z, Pan D, Hao X, Sun H (2020) Two new species of freshwater crabs of the genera Eosamon Yeo & Ng, 2007 and Indochinamon Yeo & Ng, 2007 (Crustacea, Brachyura, Potamidae) from southern Yunnan, China. ZooKeys 980: 1-21. https://doi.org/10.3897/zookeys.980.52186
|
Two new species of potamid crabs, Eosamon daiae sp. nov. and Indochinamon malipoense sp. nov. are described from the Sino-Burmese border, southwestern Yunnan and from the Sino-Vietnamese border, southeastern Yunnan, China. The two new species can be distinguished from their closest congeners by several characters, among which is the form of the first gonopod structures. Molecular analyses based on partial mitochondrial 16S rDNA sequences also support the systematic status of these new taxa.
16S rDNA, Eosamon daiae sp. nov., Indochinamon malipoense sp. nov., new species, Potamidae, Potamiscinae, taxonomy
China has the most freshwater crab species in the world and Yunnan is the epicenter of this diversity, with over 60 species in 17 genera (
Specimens were collected from southwestern and southeastern Yunnan (Fig.
Molecular data. Genomic DNA was extracted from gill tissue using the the TreliefTM Animal Genomic DNA kit (Tsingke). 16S rDNA sequence was selected for amplification with polymerase chain reaction (PCR) using the primers 1471 and 1472 (
Species | Accession No. | Voucher No. | Reference |
---|---|---|---|
Amamiku amamensis | AB428457 | – |
|
Aparapotamon grahami | AB428489 | – |
|
Apotamonautes hainanensis | AB428459 | – |
|
Arquatopotamon jizushanense | KY963596 | – |
|
Artopotamon latopeos | MH045061 | – |
|
Beccumon jarujini | AB428479 | – |
|
Candidiopotamon rathbunae | AB208598 | – |
|
Chinapotamon glabrum | AB428451 | – |
|
Demanietta renongensis | AB428475 | – |
|
Diyutamon cereum | LC198519 | – |
|
Eosamon boonyaratae | AB428487 | – |
|
Eosamon daiae sp. nov. | MT887282 |
|
This study |
Eosamon daiae sp. nov. | MT887283 |
|
This study |
MT887280 |
|
This study | |
MT887281 |
|
This study | |
Eosamon lushuiense | MT887284 |
|
This study |
Eosamon smithianum | AB428486 | – |
|
Eosamon tengchongense | MT887285 |
|
This study |
Eosamon yotdomense | AB428485 | – |
|
Esanpotamon namsom | AB428463 | – |
|
Flabellamon sp. | AB428472 | – |
|
Geothelphusa albogilva | AB127366 | – | Shih et al. 2004 |
Geothelphusa fulva | AB428456 | – |
|
Geothelphusa olea | AB428455 | – |
|
Hainanpotamon fuchengense | AB428461 | – |
|
Himalayapotamon atkinsonianum | AB428510 | – |
|
Huananpotamon angulatum | AB428454 | – |
|
Indochinamon malipoense sp. nov. | MT887278 |
|
This study |
MT887279 |
|
This study | |
Indochinamon ou | AB428481 | – |
|
Indochinamon tannanti | AB428482 | – |
|
Johora johorensis | AB290620 | – |
|
Johora murphyi | AB290621 | – |
|
Kanpotamon duangkhaei | AB428471 | – |
|
Kukrimon cucphuongensis | AB428483 | – |
|
Megacephalomon kittikooni | AB428462 | – |
|
Mindoron balssi | AB428464 | – |
|
Minpotamon nasicum | AB428450 | – |
|
Minutomon shanweiense | LC176065 | – |
|
Nanhaipotamon formosanum | AB212867 | – | Shih et al. 2005 |
Nanhaipotamon nanriense | AB212868 | – | Shih et al. 2005 |
Neotiwaripotamon jianfengense | AB428460 | – |
|
Ovitamon artifrons | AB428466 | – |
|
Parapotamon spinescens | AB428467 | – |
|
Pararanguna semilunata | AB428490 | – |
|
Paratelphusula gibbosa | AB428512 | – |
|
Potamiscus loshingense | AB428488 | – |
|
Potamiscus yiwuensis | AB428476 | – |
|
Potamiscus yunnanense | AB290629 | – |
|
Potamon fluviatile | AB428514 | – |
|
Pudaengon sakonnakorn | AB428484 | – |
|
Pupamon nayung | AB428477 | – |
|
Ryukyum yaeyamense | AB428458 | – |
|
Semicirculara lincangense | MH045059 | – |
|
Shanphusa curtobates | AB428478 | – |
|
Sinolapotamon anacoluthon | AB428453 | – |
|
Socotrapotamon nojidense | AB428493 | – |
|
Tenuilapotamon latilum | AB428468 | – |
|
Tenuipotamon huaningense | AB428491 | – |
|
Thaiphusa sp. | AB428474 | – |
|
Tomaculamon pygmaeus | AB428473 | – |
|
Trichopotamon daliense | AB428492 | – |
|
Yarepotamon gracilipa | AB428452 | – |
|
Yuebeipotamon calciatile | LC176064 | – |
|
Phylogenetic analyses. Sequences were aligned using MAFFT 7.310 (
Subfamily Potamiscinae Bott, 1970
Genus Eosamon Yeo & Ng, 2007
Holotype
: China • 1 male, 26.6 × 22.2 mm,
Eosamon tumidum (Wood-Mason, 1871): China • 1 male, 23.2 × 18.7 mm, IZCAS CB11382; Yunnan Province, Sipaishan; 1964; Eosamon tengchongense (Dai & Chen, 1985): China • 1 male, 37.9 × 30.1 mm,
Carapace slightly broader than long, dorsal surface strongly convex, densely pitted (Fig.
Carapace about 1.2 times broader than long (N = 6), subquadrate, dorsal surface strongly convex transversely and longitudinally, punctate, smooth, regions distinctly defined (Fig.
Third maxilliped merus about 1.2 times as broad as long, trapezoidal, with median depression; ischium about 1.2 times as long as broad, rectangular, with distinct median sulcus; exopod reaching proximal 1/3 of merus length with flagellum (Fig.
Chelipeds slightly unequal; merus trigonal in cross section, margins crenulated (Fig.
Ambulatory legs relatively stout, dactylus slender with spine-like setae (Fig.
Male thoracic sternum generally smooth and pitted; sternites 3, 4 fused without median suture (Fig.
Male pleon triangular, third somite widest; sixth somite about 2.2 times broader than long; telson triangular, with about 1.3 times as broad as long; the lateral margin of pleon almost straight (Fig.
G1 stout, tip of terminal segment not reaching pleonal locking mechanism in situ (Fig.
Carapace is usually dark brown, while chelipeds and ambulatory legs are usually light brown in life.
The species is named after the late Prof. Aiyun Dai, who made a huge contribution to freshwater crab studies in China during her lifetime.
Eosamon daiae sp. nov. can be distinguished from other Eosamon species by the combination of male abdomen with straight lateral margins, relatively broad G1 subterminal segment, conical and straight G1 terminal segment, the superior margin of G1 terminal segment curved and the inferior margin of G1 terminal segment comparatively straight.
Eosamon daiae sp. nov. is morphologically and geographically closest to E. tumidum (Wood-Mason, 1871), E. tengchongense (Dai & Chen, 1985) and E. lushuiense (Dai & Chen, 1985). These species are characterized by a male abdomen with straight lateral margins and superficially similar G1 structure (Fig.
Eosamon daiae sp. nov. was found in Bangyang Village (24°18'15"N, 97°47'56"E, 998 m a.s.l.), Longba Town, Longchuan County and Dengga Village (23°55'51"N, 97°47'56"E, 887 m a.s.l.), Nongdao Town, Ruili City, Dehong Prefecture in the frontier of Yunnan, China (Fig.
The new species was found not distant from localities with E. tengchongense. Indochinamon dominates the areas surrounding the new species, with I. edwardsi, I. andersonianum, I. boshanense and I. gengmaense having been recorded.
Morphological differences for Eosamon daiae sp. nov., Eosamon tumidum, Eosamon lushuiense and Eosamon tengchongense.
Character | E. daiae sp. nov. |
E. tumidum (cf. |
E. lushuiense (cf. |
E. tengchongense (cf. |
---|---|---|---|---|
Carapace | Strongly convex (Fig. |
Slightly convex | Slightly convex | Slightly convex |
Margins of G1 terminal segment | superior margin Curved, inferior margin comparatively straight (Fig. |
superior margin comparatively straight, inferior margin slightly curved (Fig. |
superior margin comparatively straight, inferior margin slightly curved (Fig. |
superior margin and inferior margin, comparatively curved (Fig. |
Distal part of G1 subterminal segment | slightly sunken (Fig. |
barely sunken (Fig. |
slightly sunken (Fig. |
obviously sunken (Fig. |
Ratio of G1 subterminal segment to terminal segment | 3–3.3 | 3.2 | 2.9 | 3.1 |
Holotype
: China • 1 male, 53.0 × 42.7 mm,
Indochinamon changpoense Dai, 1995: China • 1 male, 44.1 × 35.6 mm,
Carapace broader than long, dorsal surface glabrous, gently convex; regions indistinctly defined; anterolateral margin lined with obvious granules (Fig.
Carapace about 1.2 – 1.3 times broader than long (N = 4), subtrapezoidal, dorsal surface gently convex, glabrous; anterolateral region lined with granules, border with spinose granulation (Fig.
Ischium of third maxilliped elongate rectangular, about 1.3 times longer than broad, with distinct, longitudinal median sulcus; merus trapezoidal, about 1.1 times broader than long; exopod reaching beyond base of merus slightly, with short flagellum, about half the width of the merus (Fig.
Chelipeds unequal (Fig.
Ambulatory legs relatively slender, dactylus slender, with spine-like setae (Fig.
Thoracic sternum glabrous, sternites 1, 2 completely fused to form triangular structure; suture between sternites 2, 3 distinct (Fig.
G1 stout, bent; tip of terminal segment not reaching pleonal locking mechanism in situ (Fig.
. The crabs usually have two colors: brownish-red (Fig.
This species is named after the type locality, Malipo County, Yunnan Province, China.
Based on the morphology of G1,
All Indochinamon species have a well-developed flagellum on the exopod of the third maxilliped. The length of the flagellum varies among species. In some species, the flagellum does not exceed the width of the merus, e.g., I. tannanti, I. changpoense, I. gengmaense (Dai, 1995), I. guttus (Yeo & Ng, 1998), I. hispidum (Wood-Mason, 1871), I. jinpingense, I. mieni (Dang, 1967) and I. yunlongense. In I. malipoense sp. nov., the flagellum is about half the width of the merus, which is shorter than that in other species.
The G1 of I. malipoense sp. nov. is very similar to I. tannanti, I. changpoense, I. ahkense, and I. daweishanense. They are also geographically close. But I. malipoense sp. nov. can be distinguished from the similar I. tannanti and I. changpoense by several characters (Table
In I. khinpyae, the carapace and G1 show considerable variations (
Morphological differences for Indochinamon malipoense sp. nov., Indochinamon tannanti and Indochinamon changpoense.
Character | I. malipoense sp. nov. |
I. tannanti (cf. |
I. changpoense (cf. |
---|---|---|---|
carapace | gently convex, regions indistinctly defined (Fig. |
flat, regions distinctly defined | gently convex, regions distinctly defined |
G1 terminal segment | obviously curved, unciform (Fig. |
slightly curved, conical, with short, conspicious setae,tip tapering (Fig. |
slightly curved, conical, with few very short setae, dorsal lobe of pleopod opening visible (Fig. |
base of G1 terminal segment | slightly inflated (Fig. |
nearly straight (Fig. |
nearly straight (Fig. |
Ratio of G1 subterminal segment to terminal segment | 2.8–3.2 | 2.7 | 2.9 |
Indochinamon malipoense sp. nov. was collected from Tianbao Town (22°58'53"N, 104°50'27"E, 1075 m a.s.l.; 22°56'58"N, 104°49'48"E, 223 m a.s.l.; 23°00'07"N, 104°47'42"E, 979 m a.s.l.) and Babu Town (23°13'29"N, 104°54'04"E, 550 m a.s.l.) located in the frontier between China and Vietnam, Malipo County, Wenshan Prefecture in Yunnan, China. They were found under rocks in mountain streams with altitudes of 200–1100 m.
Indochinamon ahkense, I. changpoense, I. daweishanense, I. jinpingense, I. tannanti and Somanniathelphusa brevipodum Tai, Song, He, Cao, Xu & Zhong, 1975, have been recorded near the distribution areas of I. malipoense sp. nov..
In the present phylogenetic analyses, 60 species from 48 genera were included (Table
Phylogenetic tree reconstructed based on partial mitochondrial 16S rDNA sequences. The two new species are colored gray. Values at the nodes represent bootstrap (BS) values and posterior probability (BPP) values for ML and BI, respectively. Support values over 70/0.7 (BS/BPP) are provided.
The two new species cluster with several congeneric taxa (but not all), which tentatively supports recognition of the two genera, Eosamon and Indochinamon, following the systematic revision of
Eosamon daiae sp. nov. and Indochinamon malipoense sp. nov. are not threatened by human activity. Eosamon daiae sp. nov. is distributed in the vicinity of the Tongbiguan Nature Reserve and Indochinamon malipoense sp. nov. is distributed in the vicinity of the Laoshan Nature Reserve. In these areas, large-scale developments are strictly regulated.
Yunnan is a global biodiversity hotspot (
We thank subject editor Dr Kay Van Damme and reviewer Dr Peter K. L. Ng for their constructive criticisms, which greatly improved the manuscript. We also thank Dr Jun Chen and Mr Kaibayier Meng (National Zoological Museum of China, Institute of Zoology, Chinese Academy of Sciences) for permission of comparison of the type specimen with congeners deposited in IZCAS; We thank Zhan Zhang (College of Life Sciences, Nanjing Normal University) for assistance with collecting specimens; Yangqi Lv (College of Life Sciences, Nanjing Normal University) for help with lab work and molecular analyses; Boyang Shi (College of Life Sciences, Nanjing Normal University) for valuable comments on manuscript.
This work was supported by the National Natural Science Foundation of China (No. 31772427) and Ocean Park Conservation Foundation, Hong Kong (No. OT02.1920) to SHY. This work was also supported by Biodiversity Survey Observation and Assessment Program (2019–2023) of the Ministry of Ecology and Environment of China.