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Research Article
Oreonectes damingshanensis (Cypriniformes, Nemacheilidae), a new species of stream fish from Guangxi, Southwest China
expand article infoJing Yu‡, Tao Luo‡, Chang-Ting Lan‡, Jia-Jun Zhou§|, Huai-Qing Deng‡, Ning Xiao, Jiang Zhou‡
‡ Guizhou Normal University, Guiyang, China
§ Zhejiang Forest Resource Monitoring Center, Hangzhou, China
| Zhejiang Forestry Survey Planning and Design Company Limited, Hangzhou, China
¶ Guiyang Healthcare Vocational University, Guiyang, China

Corresponding author: Ning Xiao ( armiger@163.com )

Corresponding author: Jiang Zhou ( zhoujiang@ioz.ac.cn )

Academic editor: Tihomir Stefanov
© 2023 Jing Yu, Tao Luo, Chang-Ting Lan, Jia-Jun Zhou, Huai-Qing Deng, Ning Xiao, Jiang Zhou.
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: Yu J, Luo T, Lan C-T, Zhou J-J, Deng H-Q, Xiao N, Zhou J (2023) Oreonectes damingshanensis (Cypriniformes, Nemacheilidae), a new species of stream fish from Guangxi, Southwest China. ZooKeys 1180: 81-104. https://doi.org/10.3897/zookeys.1180.104645
ZooBank: urn:lsid:zoobank.org:pub:2D24F285-9E96-43F9-86C7-54017FF8E3E0
Open Access

Abstract

In this work, a new species of the genus Oreonectes is described, named Oreonectes damingshanensis Yu, Luo, Lan, Xiao & Zhou, sp. nov., collected from the Damingshan Mountains of the Guangxi Zhuang Autonomous Region, China. Phylogenetic trees constructed based on the mitochondrial Cyt b showed that the new species represents an independent evolutionary lineage, with uncorrected genetic distances (p-distance) from congeners ranging from 6.1% to 8.9%. Morphologically, the new species can be distinguished from five other species of the genus by a combination of characters. The discovery of this new species raises the number of known species of Oreonectes from five to six. Our study suggests that O. platycephalus may be a complex containing multiple species and that previously recorded areas need to be further delimited and reevaluated.

Key words

Morphology, new species, Oreonectes platycephalus complex, phylogeny, taxonomy

Introduction

A globally important biodiversity hotspot, the karst region of southwest China is characterized by extremely high species diversity and endemism (Wang et al. 2018). Rivers and mountains as geographic isolation are potential environmental drivers of species formation and diversification (Antonelli et al. 2018), which is also reflected in freshwater fishes from the karsts of southwest China (Wen et al. 2022). Thus, the unique geomorphological and hydrological conditions of karst may have led to the isolation of different geographical populations of widely distributed species, resulting in speciation (Jiang et al. 2022; Li et al. 2022). The large number of new fish species found in the karst region of southwest China over the past decade (Lan et al. 2013; Zhang et al. 2019) also suggests that the species diversity of its freshwater fishes may have been underestimated. Therefore, researchers are required to carry out detailed field surveys for taxonomic studies to assess the potential biodiversity of the area.

The small loaches of the genus Oreonectes Günther, 1868 (Cypriniformes, Nemacheilidae), typically have a total length of ~80 mm (Zhu 1989; Lan et al. 2013). The genus Oreonectes Günther, 1868 was initially described based on specimens collected from Hong Kong, with the type species Oreonectes platycephalus Günther, 1868 (Günther 1868) (Appendix 2: Fig. A1). However, the classification of the genus Oreonectes remains controversial and unresolved. Recently, Luo et al. (2023) conducted a phylogenetic study, which included a large genetic sample, based on mitogenome and seven nuclear genes, that largely clarified the phylogenetic relationships between species within the genera Oreonectes and Troglonectes Zhang, Zhao & Tang, 2016. Currently, there are five recognized species in the genus Oreonectes distributed in mountain streams in Guangxi, Guangdong, and Hong Kong in China, and in northern Vietnam (Zhu 1989; Lan et al. 2013), namely O. guananensis Yang, Wei, Lan & Yang, 2011, O. guilinensis Huang, Yang, Wu & Zhao, 2020, O. luochengensis Yang, Wu, Wei & Yang, 2011, O. platycephalus Günther, 1868, and O. polystigmus Du, Chen & Yang, 2008 (Du et al. 2008; Günther 1868; Huang et al. 2020; Zheng 1981; Zhu 1989; Yang et al. 2011a, b). The genus Troglonectes, after revision by from Luo et al. (2023), includes only 16 species, T. barbatus, T. canlinensis, T. daqikongensis, T. elongatus, T. furcocaudalis, T. hechiensis, T. huanjiangensis, T. lihuensis, T. lingyunensis, T. longibarbatus, T. macrolepis, T. maolanensis, T. microphthalmus, T. retrodorsalis, T. shuilongensis, and T. translucens (Li et al. 2023).

Between 2020 and 2023, we collected 30 specimens during field surveys of open streams in Nanning City, Guangxi Zhuang Autonomous Region, China (Fig. 1). Through examination of these specimens and molecular sequencing, we observed significant differences in both morphology and mitochondrial cytochrome b gene (Cyt b) in these specimens when compared with their congeners. These differences led us to identify this as a new species of the genus Oreonectes, which we named Oreonectes damingshanensis sp. nov.

Figure 1. 

Sampling collection localities and distribution of Oreonectes damingshanensis sp. nov. and five species of the genus Oreonectes in southern China. For details of ID numbers, please see Table 2. The green rectangular box without an ID is the type locality of O. platycephalus. The base maps are from the Standard Map Service website (http://bzdt.ch.mnr.gov.cn/index.html).

Materials and methods

DNA extraction, PCR, and sequencing

Genomic DNA was extracted from muscle tissue using a DNA extraction kit from Tiangen Biotech (Beijing) Co. Ltd. Two muscle samples of the new species were sequenced for the mitochondrial cytochrome b gene (Cyt b). The forward and reverse primers used for Cyt b were F14724 (5’-GACTTGAAAAACCACCGTTG-3’) and R15915 (5’-CTCCGATCTCCGGATTACAAGAC-3’), respectively, following Xiao et al. (2001). PCR amplifications were performed in a 25 μl reaction volume with the following cycling conditions: an initial denaturing step at 95 °C for five min, 36 cycles of denaturing at 95 °C for 40 s, annealing at 45 °C for 40 s and extending at 72 °C for 1 min, and a final extension at 72 °C for 10 min. The purified products were sequenced with both forward and reverse primers using a BigDye Terminator Cycle Sequencing Kit according to the manufacturer’s instructions. The products were sequenced on an ABI Prism 3730 automated DNA sequencer by Chengdu TSING KE Biological Technology Co. Ltd. (Chengdu, China). All sequences have been deposited in GenBank (Table 2).

Table 1.
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Species list of the genus Oreonectes and comparisons of diagnostic characters of the new species with congeners. Grey shading indicates a clear difference in a character compared to that of Oreonectes damingshanensis sp. nov.

Species Body pigmentation Eyes Scales Dorsal-fin rays Pectoral-fin rays Pelvic-fin rays Anal-fin rays Caudal-fin rays Caudal fin Caudal fin with irregular black markings
Oreonectes damingshanensis sp. nov. Present Normal Present iii, 7 i, 9 i, 7 iii, 5 14 Rounded Yes
O. guananensis Yang, Wei, Lan & Yang, 2011 Present Normal Present iii, 7 i, 10–11 i, 7–8 iii, 5 13–17 Rounded No
O. guilinensis Huang, Yang, Wu & Zhao, 2020 Present Normal Present ii, 6 i, 9–10 i, 6 iii, 5 13–14 Rounded Yes
O. luochengensis Yang, Wu, Wei & Yang, 2011 Absent Normal Present iii, 7 i, 11–12 i, 7 ii, 5 14–16 Truncated No
O. platycephalus Günther, 1868 Present Normal Present iii, 8–9 i, 11 i, 8 ii, 6–7 13–15 Rounded No
O. polystigmus Du, Chen & Yang, 2008 Present Normal Present iii, 6–7 i, 10 i, 6 ii, 5 14–15 Rounded No
Tip of pelvic fin reaching anus Dorsal fin origin Maxillary barbel Reference
Oreonectes damingshanensis sp. nov. No Posterior to the pelvic-fin origin Not reaching to posterior margin of gill cover This study
O. guananensis Yang, Wei, Lan & Yang, 2011 No Opposite to pelvic-fin origin Reaching to the gill cover Yang et al. 2011a; This study
O. guilinensis Huang, Yang, Wu & Zhao, 2020 Yes Slightly posterior to the pelvic-fin origin Reaching to the posterior margin of the eye Huang et al. 20120
O. luochengensis Yang, Wu, Wei & Yang, 2011 No Slightly posterior to the pelvic-fin origin Reaching to the posterior margin of the eye Yang et al. 2011b; This study
O. platycephalus Günther, 1868 No Posterior to the pelvic-fin origin Reaching to the posterior margin of the eye Günther 1868; This study
O. polystigmus Du, Chen & Yang, 2008 Yes Slightly posterior to the pelvic-fin origin Reaching to the pectoral-fin origin Du et al. 2008; This study
Table 2.
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Localities, voucher information, and GenBank numbers for all samples used.

ID Genus Species Localities (* type localities) Voucher GenBank
1 Troglonectes Troglonectes elongatus Mulun Town, Huanjiang County, Guangxi, China* GZNU 2020073101 ON116502
2 Troglonectes lihuensis Lihu Town, Nandan County, Guangxi, China* GZNU 2019011211 ON148332
3 Troglonectes daqikongensis Chaoyang Town, Libo County, Guizhou, China* GZNU 2019011207 ON116526
4 Troglonectes hechiensis Tongjin Village, Hechi City, Guangxi, China* D1820 MW495267
5 Troglonectes retrodorsalis Liuzhai Town, Nandan County, Guangxi, China* GZNU 2020073103 ON116511
6 Troglonectes shuilongensis Shuilong Town, Sandu County, Guizhou, China* GZNU 2019011201 ON116522
7 Troglonectes macrolepis Dacai Town, Huanjiang County, Guangxi, China* GZNU 2019122202 ON116498
8 Troglonectes microphthalmus Tianhe Town, Luocheng County, Guangxi, China* GZNU 2020041601 ON116494
9 Troglonectes translucens Xiaao Town, Duan County, Guangxi, China* GZNU 2020082302 ON116510
10 Troglonectes barbatus Lihu Town, Nandan County, Guangxi, China* GZNU 2020011503 ON116501
11 Troglonectes furcocaudalis Yongle Town, Rongshui County, Guangxi, China* GZNU 2020042701 ON116512
12 Paranemachilus Paranemachilus pingguoensis Changping Town, Fusui County, Guangxi, China* GZNU 2019122205 ON116500
13 Paranemachilus zhengbaoshani Duan County, Guangxi, China GZNU20210526001 ON116530
14 Paranemachilus genilepis Guohua Town, Pingguo County, Guangxi, China* GZNU 2019122206 ON116497
15 Yunnanilus (I) Yunnanilus longidorsalis Agang Longtan pool, Luoping County, Yunnan, China N/A NC_062728
16 Yunnanilus niger N/A N/A NC_063106
17 Yunnanilus jiuchiensis Jiuchi County, Penzhou City, Sichuan, China N/A MW532080
18 Karstsinnectes Karstsinnectes parva Ande Town, Jingxi City, Guangxi, China Tissue ID: JTQ02 ON116520
19 Karstsinnectes acridorsalis Bamu Town, Tiane County, Guangxi, China* Tissue ID: GZNU2020 ON116515
20 Karstsinnectes anophthalmus Leiping Town, Daxin County, Guangxi, China* GZNU 2019011310 ON116513
21 Karstsinnectes anophthalmus Leiping Town, Daxin County, Guangxi, China* GZNU 2019011210 ON148333
22 Karstsinnectes anophthalmus Chengxiang Town, Wuming County, Guangxi, China* GZNU 2019122201 ON116506
23 Micronemacheilus Micronemacheilus cruciatus N/A N/A AP012142
24 Micronemacheilus pulcherrimus Duan County, Hechi City, Guangxi, China GZNU20210609004 ON116493
25 Yunnanilus (II) Yunnanilus bailianensis Bailian cave, Liuzhou City, Guangxi, China* GZNU 2020041603 ON116504
26 Yunnanilus longibarbatus Gaoling Town, Duan County, Guangxi, China* GZNU 2020073104 ON116508
27 Oreonectes Oreonectes damingshanensis sp. nov. Leping Village, Guling Town, Mashan County, Guangxi, China* GZNU20230216010 OQ754116
28 Oreonectes damingshanensis sp. nov. Leping Village, Guling Town, Mashan County, Guangxi, China* GZNU20230216011 OQ754117
29 Oreonectes damingshanensis sp. nov. Leping Village, Guling Town, Mashan County, Guangxi, China* GZNU20230216012 OQ754118
30 Oreonectes damingshanensis sp. nov. Damingshan Mountain, Shanglin County, Guangxi, China GZNU 2020112502 ON116496
31 Oreonectes guilinensis Shigumen Village,Xingping Town,Yangshuo County, Guangxi, China* N/A MN239094
32 Oreonectes platycephalus Shenzhen City, Guangdong, China* GZNU 2020112501 ON116528
33 Oreonectes polystigmus Dabu Town, Yanshan District, Guilin, Guangxi, China* GZNU 2020011501 ON116514
34 Oreonectes polystigmus Jianghua County, Yongzhou City, Hunan, China GZNU20210609005 ON116517
35 Oreonectes guananensis Changmei Town, Huanjiang County, Guangxi, China* GZNU 2020073102 ON116507
36 Oreonectes luochengensis Tianhe Town, Luocheng County, Guangxi, China* GZNU 2020011502 ON116495
37 Lefua costata N/A N/A KT943751
38 Lefua nikkonis N/A CBM: ZF 11290 AP011300
39 Lefua echigonia Hino, Shiga, Japan N/A AB054126
40 Outgroup Traccatichthys pulcher Leiping Town, Daxin County, Guangxi, China Tissue ID: GX1 ON116516
41 Triplophysa baotianensis Nanpanjiang River, Panzhou City, Guzihou, China* GZNU20180421005 MT992550

Phylogenetic analyses

A total of 41 Cyt b sequences were used for phylogenetic analysis. In addition to the four new sequences, the remaining 37 sequences were downloaded from GenBank and included five already recognized genera (Table 2) and two outgroup species from the mitogenome provided by Luo et al. (2023).

Mitochondrial Cytb sequences were aligned in MEGA v7.0 (Kumar et al. 2016) by the MUSCLE (Edgar 2004) algorithm with default parameters. Phylogenetic trees were constructed using both maximum likelihood (ML) and Bayesian inference (BI) methods. The ML tree was conducted in IQ-TREE v2.0.4 (Nguyen et al. 2015) with 2000 ultrafast bootstrap (UFB) replicates (Hoang et al. 2018) and was run until a correlation coefficient of at least 0.99 was reached. The BI phylogeny was constructed in MrBayes v3.2.1 (Ronquist et al. 2012). Two independent runs were conducted in the BI analysis, each of which was performed for 2 × 107 generations and sampled every 1000 generations. The first 25% of the samples was discarded as a burn-in, resulting in a potential scale reduction factor of < 0.01. For BI and ML analyses, the best-fit model was obtained based on the Bayesian information criterion computed with PartitionFinder v2.1.1 (Lanfear et al. 2017). In this analysis, the first, second, and third codons of the Cyt b gene were defined.

The results of the model selection suggested that the first, second, and third codons of the best-fit model for the Cyt b gene were K80+I+G, HKY+I+G, and TRN+I+G, respectively. Nodes in the trees were considered well supported when Bayesian posterior probabilities (BPP) were ≥ 0.95 and the ML ultrafast bootstrap value (UBP) was ≥ 9 5%. Uncorrected p-distances (1000 replicates) based on the Cyt b gene were calculated using MEGA 7.0 (Kumar et al. 2016).

Morphological comparisons

Morphometric data were collected from 53 well-preserved specimens of the genus Oreonectes (Appendix 3: Table A1). A total of 33 measurements were recorded to the nearest 0.1 mm with digital calipers following the protocol of Tang et al. (2012). All measurements were taken on the left side of the fish specimens.

Comparative data for the five species of the genus Oreonectes were obtained from the literature and specimen examination (Table 4). Specimens of four species from the type locality were examined, including O. guananensis, O. luochengensis, O. platycephalus, and O. polystigmus (see Appendix 1). Considering the morphological similarity of the new species to O. platycephalus and O. polystigmus, the measurements were also included in the statistical analysis. Principal component analyses (PCAs) of size-corrected measurements and simple bivariate scatterplots were used to explore and characterize the morphometric differences between the new species and O. platycephalus and O. polystigmus. Mann–Whitney U tests were used to determine the significance of differences in morphometric characters between the new species and the above two similar species. All statistical analyses were performed using SPSS 21.0 (SPSS, Inc., Chicago, IL, USA), and differences were considered statistically significant at a p-value < 0.05. PCAs of morphological data were performed after logarithmic transformation and under conditions of no rotation. In addition, as reported by other researchers (Parsons and Jones 2000; Polaszek et al. 2010), canonical discriminant analysis (CDA, George and Paul 2010) was used to classify individuals into different groups, where a priori membership was determined based on specimens belonging to different species. All pre-processing of morphological data was performed in Microsoft Excel (Microsoft Corporation 2016).

X-ray scanning and three-dimensional image reconstructions

In order to obtain information on the skeletons of the new species, X-ray scanning was conducted via nano-computerized tomography. Specimens were scanned using a GE v|tome|x m dual tube 300/180 kv system at the Key Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate Paleontology and Paleoanthropology (IVPP), Chinese Academy of Sciences. Each specimen was scanned with an energy beam of 80 kV and a flux of 80 μA using a 360° rotation, and the data were then reconstructed into a 4096 × 4096 matrix of 1536 slices. The final CT reconstructed skull images were exported with a minimum resolution of 6.099 μm. The skull images were exported from the virtual 3D model and reconstructed by Volume Graphics Studio 3.0.

Results

Phylogenetic analyses and genetic divergence

BI and ML analyses were performed to construct phylogenetic trees with consistent topologies based on mitochondrial Cyt b sequences with a length of 1140 base pairs (Fig. 2). These phylogenetic trees showed a topology similar to that of Luo et al. (2023), but with lower node support between major clades (Fig. 2). In addition, several new clades were identified, and Yunnanilus was divided into two distant clades named Yunnanilus (I) and Yunnanilus (II). K. anophthalmus, K. parva, and K. acridorsalis were clustered together to form a separate clade. In fact, all five remaining species of the genus Oreonectes, clustered together to form a sister clade of the genus Lefua. Within the genus Oreonectes, the four specimens collected from Mashan and Shanglin counties in Nanning City, Guangxi, China, formed a distinct and highly supported clade with O. platycephalus and O. guilinensis (0.99 in BI and 85% in ML) (Fig. 2).

Figure 2. 

Phylogenetic tree based on mitochondrial Cyt b (1140 bp). In this phylogenetic tree, Bayesian posterior probabilities (BPP) from BI analysis/ultrafast bootstrap supports (UFB) from ML analysis are listed beside nodes. The scale bar represents 0.08 nucleotide substitutions per site. The numbers at the tip of branches correspond to the ID numbers listed in Table 2.

Within the genus Oreonectes, the genetic distances between the new species Oreonectes damingshanensis sp. nov. and the remaining five species range from 6.1% (for O. polystigmus) to 8.9% (for O. guananensis). This level of divergence was similar to those between pairs of other recognized species. For example, the Cyt b p-distance was 4.9% between O. luochengensis and O. guananensis (Table 3).

Table 3.
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Uncorrected p-distances (%) between five species of the genus Oreonectes based on the mitochondrial Cyt b gene.

ID Species 1 2 3 4 5
1 Oreonectes damingshanensis sp. nov.
2 Oreonectes guananensis 8.9
3 Oreonectes guilinensis 7.2 8.8
4 Oreonectes luochengensis 7.7 4.9 8.1
5 Oreonectes polystigmus 6.1 8.6 7.4 7.6
6 Oreonectes platycephalus 6.8 8.8 6.5 8.0 6.5

Morphological analyses

Mann–Whitney U tests showed that the Oreonectes damingshanensis sp. nov. differed from O. luochengensis, O. polystigmus, O. guananensis, and O. platycephalus in several morphological characters (Table 4). These significant differences were mainly observed in the head, fins, and tail regions. The differences were more pronounced in comparisons of the new species with O. platycephalus, with 84.8% of the morphological characters being significantly different (p = 0.00−0.046) (Table 4). Based on PCA of the morphological data, two principal component factors with eigenvalues greater than one were extracted. These accounted for 84.09% of the total variation (Appendix 4: Table A2). The first principal component (PC1) accounted for 77.92% of the variation and was positively correlated with all variables (eigenvalue = 28.91), thus reflecting the morphological differences between Oreonectes damingshanensis sp. nov. and similar species. This axis corresponded to body length, head, fins, nostrils, and barbel length. Thus, based on the statistical analysis of the measurements and the PCA and CDA results, 30 specimens from Oreonectes damingshanensis sp. nov. were clearly distinguished via morphological characters from the four similar species O. luochengensis, O. polystigmus, O. guananensis, and O. platycephalus. The second principal component (PC2) accounted for 6.17% of the variation and was influenced by the length of the distance between posterior nostrils, length of the upper jaw, mouth width, and eye width (eigenvalue = 0.04) (Appendix 4: Table A2). The two-dimensional plots of PC1 and PC2 clearly separated Oreonectes damingshanensis sp. nov. from O. polystigmus and O. platycephalus (Fig. 3A). CDA correctly classified 100% of the individuals in the initial grouping case for the three sample groups (N = 40). Canonical axes (CAN) 1–2 explained 75.8% and 24.2% of the total variation (Fig. 3B; Appendix 4: Table A2).

Table 4.
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Morphological comparisons of Oreonectes damingshanensis sp. nov. (OD), O. luochengensis (OL), O. guananensis (OG), O. platycephalus (OPL), and O. polystigmus (OPO). All units in mm. P-values are at 95% significance.

O. damingshanensis (OD) O. luochengensis (OL) O. guananensis (OG) O. platycephalus (OPL) O. polystigmus (OPO) P-value from Mann-Whitney U test
Range Mean ± SD Range Mean ± SD Range Mean ± SD Range Mean ± SD Range Mean ± SD OD vs OL OD vs OG OD vs OPL OD vs OPO
Total length 55.7–98.9 73.5 ± 9.5 61.7–80.6 72.1 ± 8.2 50.5–89.0 68.4 ± 18.1 41.0–85.5 56.3 ± 15.1 61.5–66.9 65.3 ± 2.5 0.909 0.536 0.005 0.073
Standard length 46.2–81.8 60.6 ± 8.1 51.7–66.2 59.5 ± 6.2 40.6–73.8 56.7 ± 14.8 33.1–73.6 48.1 ± 13.8 51.2–55.5 54.2 ± 2.0 0.802 0.567 0.012 0.093
Body depth 7.0–14.8 9.4 ± 1.7 6.2–9.3 8.1 ± 1.3 4.5–9.8 7.4 ± 2.2 4.6–12.2 7.0 ± 2.6 6.0–11.4 8.8 ± 2.3 0.128 0.086 0.006 0.699
Body width 4.6–10.2 6.7 ± 1.2 6.3–9.4 7.2 ± 1.3 4.2–6.9 5.6 ± 1.2 2.8–7.6 4.5 ± 1.7 5.5–8.7 7.0 ± 1.4 0.802 0.069 0.005 0.738
Head length 10.2–16.6 13.3 ± 1.7 10.6–13.2 12.1 ± 1.0 5.1–16.8 11.7 ± 4.9 6.6–16.7 10.1 ± 3.5 10.2–12.5 11.6 ± 1.0 0.069 0.536 0.010 0.022
Head depth 5.4–9.5 7.2 ± 1.0 5.6–7.3 6.5 ± 0.6 3.3–6.5 4.7 ± 1.5 2.9–6.5 4.8 ± 1.3 5.7–7.8 6.8 ± 1.0 0.069 0.001 0.000 0.485
Head width 7.7–13.4 9.7 ± 1.3 5.6–7.6 6.7 ± 0.9 4.3–8.6 7.0 ± 1.8 4.5–9.1 6.7 ± 1.5 7.4–8.1 7.7 ± 0.3 0.000 0.002 0.000 0.000
Distance between anterior nostrils 2.8–6.5 3.9 ± 0.7 2.3–3.3 2.9 ± 0.4 1.8–4.0 2.9 ± 1.0 1.7–3.8 2.4 ± 0.8 2.4–2.9 2.7 ± 0.2 0.002 0.043 0.001 0.000
Distance between posterior nostrils 3.4–6.5 4.7 ± 0.7 3.1–4.8 3.9 ± 0.7 2.6–6.6 4.5 ± 1.5 2.3–6.1 4.0 ± 1.3 4.2–5.1 4.5 ± 0.4 0.022 0.697 0.052 0.453
Distance between anterior and posterior nostrils 0.6–1.5 0.9 ± 0.2 1.1–1.4 1.2 ± 0.1 1.2–1.8 1.4 ± 0.2 0.6–1.5 0.9 ± 0.3 1.0–1.2 1.1 ± 0.1 0.001 0.000 0.918 0.015
Snout length 4.2–7.1 5.5 ± 0.8 4.1–7.7 5.3 ± 1.4 3.6–6.8 5.1 ± 1.3 1.9–7.0 4.0 ± 1.7 4.4–10.7 6.1 ± 3.1 0.321 0.448 0.006 0.338
Upper jaw length 2.2–4.1 3.2 ± 0.4 2.3–2.9 2.6 ± 0.3 1.7–3.7 2.6 ± 0.8 1.2–3.5 2.0 ± 0.8 2.1–2.6 2.3 ± 0.2 0.004 0.185 0.003 0.001
Lower jaw length 0.3–3.3 2.4 ± 0.5 1.8–2.5 2.2 ± 0.3 1.5–2.8 2.1 ± 0.5 0.9–2.4 1.5 ± 0.5 1.5–1.9 1.7 ± 0.2 0.116 0.155 0.001 0.001
Mouth width 2.5–6.4 4.7 ± 0.8 3.1–4.0 3.7 ± 0.3 2.0–4.4 3.1 ± 1.0 1.6–4.1 2.8 ± 0.8 2.6–3.6 3.1 ± 0.4 0.003 0.003 0.000 0.001
Eye diameter 0.9–2.0 1.6 ± 0.3 5.5–6.6 6.0 ± 0.5 3.7–7.8 5.8 ± 1.9 0.5–1.9 1.1 ± 0.6 0.8–1.1 0.9 ± 0.2 0.000 0.000 0.046 0.001
Interorbital distance 4.4–7.7 5.6 ± 0.9 1.6–2.2 1.9 ± 0.3 1.1–2.1 1.7 ± 0.4 3.7–8.2 5.2 ± 1.6 5.0–6.8 6.1 ± 0.8 0.000 0.000 0.217 0.218
Predorsal length 27.0–48.7 36.5 ± 5.1 29.8–38.2 34.2 ± 3.6 22.5–42.5 32.4 ± 9.1 19.7–43.1 28.8 ± 7.9 29.6–33.2 31.9 ± 1.7 0.345 0.477 0.016 0.064
Dorsal-fin base length 4.9–9.1 6.2 ± 1.0 4.1–6.2 5.2 ± 1.0 2.5–7.3 5.0 ± 1.8 2.1–6.4 3.9 ± 1.4 4.4–5.9 5.0 ± 0.6 0.069 0.141 0.001 0.008
Dorsal-fin length 8.8–14.7 11.4 ± 1.4 9.4–12.3 10.5 ± 1.2 7.2–14.9 10.9 ± 3.1 4.9–9.9 7.6 ± 1.7 9.0–9.7 9.5 ± 0.3 0.202 0.506 0.000 0.002
Pectoral-fin length 8.1–13.2 10.1 ± 1.3 7.9–11.9 10.1 ± 1.6 5.3–11.5 8.7 ± 2.7 5.1–10.8 7.7 ± 1.9 8.8–9.3 9.1 ± 0.2 0.945 0.421 0.006 0.082
Pectoral-fin base length 1.8–3.5 2.4 ± 0.4 1.6–2.8 2.0 ± 0.5 1.1–2.3 1.8 ± 0.5 1.3–2.7 1.9 ± 0.5 1.6–2.7 2.3 ± 0.5 0.048 0.002 0.014 0.485
Prepectoral length 9.8–17.3 13.2 ± 1.7 11.4–15.1 12.9 ± 1.4 9.6–17.2 13.5 ± 3.3 7.0–17.6 10.6 ± 3.7 11.1–12.8 12.0 ± 0.8 0.598 0.909 0.014 0.117
Pelvic-fin length 6.9–12.3 9.6 ± 1.3 6.6–11.4 8.7 ± 1.8 5.5–10.2 8.0 ± 2.1 5.3–11.1 8.0 ± 1.9 7.1–8.0 7.5 ± 0.4 0.237 0.141 0.052 0.005
Pelvic-fin base length 1.5–3.3 2.3 ± 0.4 1.6–2.0 1.7 ± 0.2 0.8–1.9 1.2 ± 0.5 1.2–2.6 1.7 ± 0.5 1.4–1.7 1.6 ± 0.1 0.001 0.000 0.009 0.001
Prepelvic length 23.8–41.4 31.0 ± 4.3 28.5–36.2 32.2 ± 3.3 22.9–40.4 30.9 ± 8.5 16.8–39.3 24.3 ± 7.9 26.1–30.3 28.8 ± 1.9 0.567 0.631 0.012 0.131
Anal-fin length 8.3–13.6 10.4 ± 1.2 7.5–9.9 8.6 ± 1.0 6.7–12.0 9.0 ± 2.5 4.8–8.7 7.5 ± 1.4 7.6–8.6 8.1 ± 0.4 0.003 0.369 0.000 0.000
Anal-fin base length 4.2–7.2 5.2 ± 0.6 2.0–5.7 3.9 ± 1.4 3.4–5.1 4.2 ± 0.8 2.0–5.2 3.6 ± 1.0 3.9–5.0 4.2 ± 0.6 0.025 0.016 0.001 0.007
Preanal length 34.5–61.3 46.0 ± 6.4 30.7–53.6 42.2 ± 8.2 32.7–57.2 44.3 ± 11.3 24.4–56.0 36.3 ± 10.6 38.1–44.7 42.3 ± 2.9 0.345 0.697 0.012 0.131
Caudal peduncle length 6.4–14.6 9.3 ± 1.6 6.8–8.1 7.4 ± 0.5 7.1–9.0 8.1 ± 0.8 5.6–11.1 7.7 ± 1.9 6.5–9.9 8.8 ± 1.5 0.004 0.048 0.052 0.661
Caudal peduncle depth 4.9–9.5 6.6 ± 1.0 4.7–6.4 5.6 ± 0.7 3.4–8.1 5.7 ± 2.1 3.5–7.6 5.2 ± 1.4 4.4–5.9 5.3 ± 0.7 0.014 0.536 0.018 0.013
Maxillary barbel length 4.4–8.1 5.8 ± 0.9 5.1–6.8 5.8 ± 0.9 3.6–8.9 6.4 ± 2.1 1.8–6.2 3.9 ± 1.6 5.2–6.9 5.9 ± 0.7 0.909 0.421 0.003 0.817
Inrostral barbel length 3.5–5.6 4.5 ± 0.6 3.6–4.7 4.0 ± 0.5 2.2–7.0 4.2 ± 1.8 1.5–5.5 3.3 ± 1.3 4.4–6.1 5.0 ± 0.8 0.105 0.369 0.008 0.239
Outrostral barbel length 5.3–9.7 6.9 ± 1.0 4.5–7.4 5.9 ± 1.2 4.2–9.1 6.8 ± 2.1 3.4–8.1 4.9 ± 1.6 6.0–8.1 7.0 ± 0.9 0.105 0.802 0.005 0.817
Figure 3. 

Plots from the principal component analysis, and canonical discriminant analysis scores of Oreonectes damingshanensis sp. nov., O. polystigmus, and O. platycephalus based on morphological characters.

Taxonomic account

Oreonectes damingshanensis Yu, Luo, Lan, Xiao & Zhou, sp. nov.

https://zoobank.org/FAE4223D-632B-4CE6-8990-6EAD4D410233
Figs 4, 5, 6; Appendix 3: Table A1

Chresonymy

Oreonectes platycephalus (Günther, 1868): Wang 2022 (Guangxi, China); Luo et al. 2023 (Damingshan Mountains, Shanglin County, Guangxi, China).

Material

Holotype. GZNU20230216001, 98.9 mm total length (TL), 81.8 mm standard length (SL), collected by Jing Yu on February 16, 2023, in Waminggu Scenic Area, Leping Village, Guling Town, Mashan County, Guangxi Zhuang Autonomous Region, China (23.60818443°N, 108.29426408°E; ca. 234 m a.s.l.). Paratypes. Twenty-four specimens from the same locality as the holotype: GZNU20230216002–216025, 46.2−70.7 mm SL, collected by Jing Yu and Tao Luo on February 16, 2023. Five specimens from Damingshan Mountains, Shanglin County, Guangxi: GZNU2020011505–011509, 59.2−76.7 mm SL, collected by Yali Wang and Tao Luo on February 16, 2021.

Etymology

The species epithet damingshanensis refers to the type locality, located within the Damingshan Mountains, Guangxi, China. The suggested English name is the Damingshan Mountains loach, and the Chinese name is Dà Míng Shān Lıˇng Qiū (大明山岭鳅).

Diagnosis

Oreonectes damingshanensis sp. nov. is assigned to the genus Oreonectes based on molecular phylogenetic analyses and the following characteristics, which are diagnostic for this genus: (1) anterior and posterior nostrils narrowly separated; (2) lips smooth, with furrows; (3) barbel-like elongation of anterior nostrils longer than depth of nostril tube; and (4) caudal fin rounded, dorsal fin with 6 or 7 branched rays (Du et al. 2023).

Oreonectes damingshanensis sp. nov. can be distinguished from all other congeners by the following combination of characters: (1) body pigmentation present; (2) eyes normal, diameter 6.5–17.1% of head length; (3) caudal fin rounded, with irregular black markings; (4) body completely covered with fine scales except for the head; (5) lateral line incomplete, with 14 or 15 pores, last lateral line pore reaching above the tip of pectoral fin; (6) dorsal-fin rays, iii-7; (7) pectoral-fin rays, i-9; (8) anal-fin rays, iii-5; (9) pelvic-fin rays, i-7; (10) 14 branched caudal-fin rays; (11) tip of ventral fin extended backward, not reaching the anus; (12) dorsal fin origin posterior to the pelvic-fin origin; (13) inrostral barbel extending backward and not reaching the anterior margin of the eye; (14) tip of maxillary barbel not reaching the posterior margin of the gill cover; and (15) vertebrae 4 + 34.

Description

Body elongated and cylindrical, with the insignificant depth decreasing from dorsal-fin origin to caudal-fin base. Head short, length 13.3 mm, slightly depressed and flattened, width greater than depth (head width/head depth = 1.3). Snout round, oblique and flat, length 38.0–45.3% of head length (HL). Mouth inferior, curved, upper and lower lips smooth, lower lip with a V-shaped median notch. Three pairs of barbels are long: inrostral barbel length 25.9–38.3% of HL, extending backward and not reaching the anterior margin of eye; outrostral barbel length 42.4–62.4% of HL, extending backward beyond the posterior margin of the eye. Maxillary barbel length 36.0–56.6% of HL, tip of maxillary barbel not reaching to posterior margin of gill cover. Anterior and posterior nostrils narrowly separated, length 33.5–84.2% of eye diameter. Anterior nostril tube short, with an elongated short barbel-like tip. Eyes present, normal, diameter of 6.5–17.1% HL. Gill opening small; gill rakers not developed, nine inner gill rakers on the first gill arch (n =1) (Fig. 4D).

Figure 4. 

Morphological characteristics of the holotype GZNU20230216001 of Oreonectes damingshanensis sp. nov. in preservative (10% formalin) A lateral view B dorsal view C ventral view D gill raker E enlarged anterior and posterior nostrils.

Dorsal-fin rays iii-7, pectoral-fin rays i-9, pelvic-fin rays i-7, anal-fin rays iii-5, 14 branched caudal fin rays. Dorsal fin short, length 15.8–22.6% of SL, distally margin round, origin posterior to pelvic-fin insertion, situated slightly posterior to two-thirds the distance between snout tip and caudal-fin base. Pectoral fin short, length 15.2–19.5% of SL, tip of pectoral fin extending backward to ~56.7% of the distance between the origin of pectoral and pre-pelvic fins. Pelvic fin length 13.1–17.2% of SL, tips of pelvic fin not reaching anus, distance between tips of pelvic fin and anus 2.0 times the eye diameter. Anal fin long, length 15.3–179.7% of SL, tips of anal fin not reaching caudal-fin base, distance between tips of anal fin and anus 0.64 times the eye diameter. Caudal fin rounded, caudal peduncle length 9.3 mm, without adipose crests along either dorsal or ventral sides. Vertebrae 38 comprising of 4 Weberian + 22 abdominal + 11 caudal + 1 compound centrum (Fig. 5).

Figure 5. 

The three-dimensional reconstructed model of the skeleton of Oreonectes damingshanensis sp. nov. (paratype GZNU20230216021, standard length 57.0 mm) A dorsal view B ventral view, and C latera view. Caudal fin slightly broken.

Except for the head, body completely covered by scales. Lateral line incomplete, exceeding tip of pectoral fin but not reaching base of caudal fin, with 14 or 15 pores, last lateral line pore reaching above the tip of pectoral fin. Cephalic lateral-line system, with eight supraorbital, 5 + 8 infraorbital canal pores, three supratemporal canal pores, with eight preoperculo-mandibular canal pores. Two chambers of air-bladder, posterior chamber developed, filling the body cavity and connected with anterior chamber by a long, slender tube. Lateral wall of the bony capsule of the swim bladder is membranous and closed posteriorly (Fig. 5).

Coloration

In life, body pale yellow-brown overall, dark brown between anterior margin of eyes to outrostral barbel, brown lateral stripe on flank of the body, irregular black spots present on dorsal and lateral surfaces and caudal fin, black at base of caudal fin, pale brown on each fin (Fig. 6). In 10% formalin, the body color was dark brown (Fig. 4).

Figure 6. 

Live paratype of Oreonectes damingshanensis sp. nov.

Comparisons

Comparative data of Oreonectes damingshanensis sp. nov. with the five known species within the genus Oreonectes are given in Table 1.

Oreonectes damingshanensis sp. nov. can be distinguished from O. luochengensis by nine branched pectoral-fin rays (vs 11 or 12), lateral line pores 14 or 15 (vs 6–13), caudal fin rounded, with irregular black markings (vs truncated, without irregular black markings), body covered with scales except for the head (vs degraded, body scales hidden under the skin), and vertebrae 4 + 34 (vs 4 + 32 /35).

Oreonectes damingshanensis sp. nov. can be distinguished from O. guilinensis by dorsal-fin rays (iii, 7 vs ii, 6), seven branched pelvic-fin rays (vs 6), lateral line pores 14 or 15 (vs 4–6), black at base of caudal fin (vs absence), maxillary barbel extending backward, not reaching to the posterior margin of the gill cover (vs reaching to posterior margin of the eye), and tip of pelvic fin not reaching to anus (vs reaching to anus).

Oreonectes damingshanensis sp. nov. can be distinguished from O. guananensis by nine branched pectoral-fin rays (vs 10 or 11), dorsal fin origin posterior to pelvic-fin origin (vs opposite to pelvic-fin origin), maxillary barbel extending backward and not reaching to posterior margin of gill cover (vs reaching to the gill cover), lateral line pores 14 or 15, last lateral line pore reaching above the tip of pectoral fin (vs 7–13, last lateral line pore not reaching above the tip of pectoral fin), caudal fin with irregular black markings (vs without irregular black markings), vertebrae 4 + 34 (vs 4 + 32), relatively small eye diameter (1.6 ± 0.3 mm vs 5.8 ± 1.9 mm, p-value = 0.00, Table 4) and some significant morphological differences (p-values < 0.05), including head depth (4.7 ± 0.8 mm vs 3.1 ± 1.0 mm), head width (9.7 ± 1.3 mm vs 7.0 ± 1.8 mm), mouth width (7.2 ± 1.0 mm vs 4.7 ± 1.5 mm), interorbital distance (5.6 ± 0.9 mm vs 1.7 ± 0.4 mm), pectoral-fin base length (2.4 ± 0.4 mm vs 1.8 ± 0.5 mm), pelvic-fin base length (2.3 ± 0.4 mm vs 1.2 ± 0.5 mm), and anal-fin base length (5.2 ± 0.6 mm vs 4.2 ± 0.8 mm).

Oreonectes damingshanensis sp. nov. differs from O. platycephalus by having seven branched dorsal-fin rays (vs 8 or 9), nine branched pectoral-fin rays (vs 11), seven branched pelvic-fin rays (vs 8), anal-fin rays (iii, 5 vs ii, 6 or 7), nine inner gill rakers on the first gill arch (vs 14 or 15), and maxillary barbel extending backward, not reaching to the posterior margin of the gill cover (vs reaching to the posterior margin of the eye).

Oreonectes damingshanensis sp. nov. can be distinguished from O. polystigmus by having seven branched pelvic-fin rays (vs 6), nine branched pectoral-fin rays (vs 10), seven branched pelvic-fin rays (vs 6), anal-fin rays (iii, 5 vs ii, 5), lateral line pores 14 or 15 (vs 6–8), nine inner gill rakers on first gill arch (vs 13 or 14), tip of pelvic fin not reaching to anus (vs reaching to anus), maxillary barbel extending backward, not reaching the posterior margin of the gill cover (vs reaching the pectoral-fin origin), and vertebrae 4 + 34 (vs 4 + 32) . In addition to differences in each fin, the new species also differed significantly from O. polystigmus in a number of measurable characters. These included larger head length (13.3 ± 1.7 mm vs 11.6 ± 1.0 mm), head width (9.7 ± 1.3 mm vs 7.7 ± 0.3 mm), mouth width (4.7 ± 0.8 mm vs 3.1 ± 0.4 mm), eye diameter (1.6 ± 0.3 mm vs 0.9 ± 0.2 mm), dorsal-fin length (11.4 ± 1.4 mm vs 9.5 ± 0.3 mm), pelvic-fin length (9.6 ± 1.3 mm vs 7.5 ± 0.4 mm), and anal-fin length (10.4 ± 1.2 mm vs 8.1 ± 0.4 mm) (p-value < 0.05; Table 4).

Distribution, habitat, and populations

Based on current field surveys, the new species Oreonectes damingshanensis sp. nov. has only been found in streams in the Damingshan Mountains of Mashan and Shanglin counties in the Guangxi Zhuang Autonomous Region of China belonging to the Hongshuihe River basin of the Pearl River system. The new species is easy to collect in the streams of the Damingshan Mountains area where it has a large population.

Key to species of the gneus Oreonectes

1 Body pigmentation absent, caudal fin truncated O. luochengensis
– Body pigmentation present, caudal fin rounded 2
2 Caudal fin with irregular black markings 3
– Caudal fin without irregular black markings 4
3 Seven branched dorsal-fin rays, tip of pelvic fin not reaching anus O. damingshanensis sp. nov.
– Six branched dorsal-fin rays, tip of pelvic fin reaching anus O. guilinensis
4 Dorsal fin origin opposite to pelvic-fin origin O. guananensis
– Dorsal fin origin posterior to pelvic-fin origin 5
5 Tip of pelvic fin not reaching anus, maxillary barbels reaching posteriorly to the posterior margin of eye O. platycephalus
– Tip of pelvic fin not reaching anus, maxillary barbels reaching posteriorly to the pectoral-fin origin O. polystigmus

Discussion

Both morphological (see comparisons above) and mitochondrial genetic differences, i.e., forming a distinct lineage with an uncorrected p-distance of 6.1% from O. polystigmus, support the validity of Oreonectes damingshanensis sp. nov., a new species found in the mountain streams of the Damingshan Mountains, Nanning City, Guangxi, China (Fig. 1). With the addition of this new species, the true genus Oreonectes now comprises six species, namely Oreonectes damingshanensis sp. nov., O. guananensis, O. guilinensis, O. luochengensis, O. platycephalus, and O. polystigmus. In the phylogenetic tree, the new species Oreonectes damingshanensis sp. nov. from Damingshan Mountains is not fully resolved and supported, although it forms a sister clade with (O. guilinensis + O. platycephalus) (Fig. 2). This may be related to the number and length of molecular markers and the number of species. In the phylogenetic tree reconstructed by Luo et al. (2023) based on the mitochondrial genome and seven nuclear genes, O. platycephalus (No. 27, i.e., Oreonectes damingshanensis sp. nov.) from the Damingshan Mountains was considered to be a sister species of O. polystigmus, which was strongly supported by the BI tree but not fully resolved in the ML tree. This may be related to the absence of O. guilinensis. Therefore, the inclusion of a sufficient number of sampled species and molecular markers in future studies may help to resolve interspecific phylogenetic relationships within the genus Oreonectes.

The widely distributed species O. platycephalus Günther, 1868 may be a complex containing multiple cryptic species. O. platycephalus was originally described from specimens collected from small streams near the top of Hong Kong Mountains, the type locality (Günther 1868), and it has been extensively recorded from various tributary areas of the Pearl River Basin (the Luofu Mountains, the Baiyun Mountains and eastern Guangdong, and Jinxiu, Rong’an, and Zhaoping counties in Guangxi), including areas in northern Vietnam (Fig. 1) (Zhu 1989; Kottelat 2001; Zhang et al. 2016). The wide geographical distribution, morphological similarity, and classification based on morphological characteristics of species from the same basin may lead to different geographical populations of the species being identified as a single species, resulting in an underestimation of species diversity. The combination of mitochondrial differences and morphological characteristics of O. guilinensis supports this hypothesis (Huang et al. 2020). Furthermore, the small-bodied, widely distributed species of Oreonectes may rapidly form new species due to the geographical isolation of water systems, as shown in Fig. 1 and the phylogenetic tree (Fig. 2). Therefore, we recommend that a comprehensive and systematic survey (especially concerning the grey shaded area in Fig. 1) of O. platycephalus be carried out to assess its species diversity.

In the newly described species Oreonectes damingshanensis sp. nov. and the other five species, O. guananensis and O. luochengensis are the most northerly distributed and have adjacent distributions and phylogenies, followed by O. polystigmus and finally O. guilinensis and O. platycephalus. By combining the positions of these species in the phylogenetic tree, we propose the hypotheses of “neighboring and closely related” and “northern Guangxi origin with southward dispersal”, i.e., within the genus Oreonectes, the shorter the distance between species, the more closely related they are in the phylogenetic tree, and the earlier the species formed at the northern tip of their distribution. These “neighboring and closely related”, “microlocalism”, and “north to south” patterns of geographic distribution and phylogeny suggest that Oreonectes is a good candidate for speciation and biogeographic studies in the Pearl River Basin. To test this hypothesis, future studies could focus on population genetics and biogeographic study of the O. platycephalus complex.

Acknowledgments

We thank LetPub (www.letpub.com) for its linguistic assistance during manuscript preparation. We are very grateful to the subject editor, Tihomir Stefanov, and two reviewers for their suggested changes to this manuscript.

Additional information

Conflict of interest

The authors have declared that no competing interests exist.

Ethical statement

No ethical statement was reported.

Funding

This research was supported by the Guizhou Normal University Academic Emerging Talent Fund Project (Qianshi Xin Miao [2021] 20) and the Postgraduate Education Innovation Program of Guizhou Province (No. Qianjiaohe YJSKYJJ [2021] 091).

Author contributions

Jing Yu and Jiang Zhou conceived and designed the research; Tao Luo, Jing Yu, Chang-Ting Lan, Jia-Jun Zhou conducted field surveys and collected samples; Tao Luo, and Chang-Ting Lan performed molecular work; Jing Yu, Tao Luo, and Ning Xiao processed the English language of the manuscript; Jing Yu, Tao Luo, Huai-Qing Deng, and Jiang Zhou wrote and discussed and revised the manuscript. All authors read and approved the final version of the manuscript.

Author ORCIDs

Jing Yu https://orcid.org/0009-0004-3629-3826

Tao Luo https://orcid.org/0000-0003-4186-1192

Chang-Ting Lan https://orcid.org/0009-0007-2381-3601

Jia-Jun Zhou https://orcid.org/0000-0003-1038-1540

Huai-Qing Deng https://orcid.org/0000-0002-6645-2291

Ning Xiao https://orcid.org/0000-0002-7240-6726

Jiang Zhou https://orcid.org/0000-0003-1560-8759

Data availability

All of the data that support the findings of this study are available in the main text or Appendices.

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Appendix 1

Specimens examined in this work.

Oreonectes guananensis (n = 5): China: Guangxi: Huanjiang County: Changmei Town (type locality): GZNU2020050201–050205.

Oreonectes luochengensis (n = 5): China: Guangxi: Luocheng County: Tianhe Town (type locality): GZNU2017001–005.

Oreonectes platycephalus (n = 6): China: Guangdong: Shenzhen City: Wutong Mountain: GZNU2020011510–011515.

Oreonectes polystigmus (n = 4): China: Guangxi: Guilin City: Yanshan District: Dabu Town (type locality): GZNU201908004–908007.

Appendix 2

Figure A1. 

The original description of the Oreonectes platycephalus Zhu, 1989. Provided by J-J Zhou, February 13, 2023.

Appendix 3

Table A1.
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Measurements of the five specimens of Oreonectes damingshanensis sp. nov. and other species. All units in mm. *designates the holotype.

ID Species Voucher number Total length Standard length Body depth Body width Head length Head depth Head width Distance between anterior nostrils Distance between posterior nostrils Distance between anterior and posterior nostrils Snout length Upper jaw length Lower jaw length Mouth width Eye diameter Interorbital distance Predorsal length Dorsal-fin base length Dorsal-fin length Pectoral-fin length Pectoral-fin base length Prepectoral length Pelvic-fin length Pelvic-fin base length Prepelvic length Anal-fin length Anal-fin base length Preanal length Caudal peduncle length Caudal peduncle depth Maxillary barbel length Inrostral barbel length Outrostral barbel length
1 O. damingshanensis sp. nov. GZNU20230216001 98.9 81.8 14.8 10.2 16.6 9.5 13.4 6.5 6.5 1.1 7.1 4 3.3 5.9 1.9 7.4 48.7 8.6 14.7 13 3.5 15.7 12.3 3.3 41.4 13.6 6.5 61.3 14.6 9.5 8.1 5.2 9.7
2 O. damingshanensis sp. nov. GZNU20230216002 77.8 63.5 10.9 7.2 13.6 7.9 9.5 3.6 4.9 1.1 5.4 3.4 2.2 4.7 1.6 5.8 38.6 7.2 13.8 11.5 2.4 13.5 10.9 2.5 31.5 11.5 5.7 47.5 10.3 6.7 4.9 3.9 7.4
3 O. damingshanensis sp. nov. GZNU20230216003 75.3 61.8 9 6.5 12.5 6.9 9.7 3.5 4.7 1 5.1 3.1 2.6 5 1.9 5.3 37.4 6.7 11.9 11.3 2.8 12.7 10.2 2.6 30 10.7 5.5 46.1 9 7 5.7 4.4 6.2
4 O. damingshanensis sp. nov. GZNU20230216004 86.9 70.7 10.5 8.1 16.2 8.8 12.6 5.1 6.1 1.5 7 4.1 3.2 6.4 1.9 6.7 42.4 7.7 13.5 13.2 2.8 16.1 11.8 3 36 11.4 5.6 53.3 11.8 7.5 7 4.2 8.8
5 O. damingshanensis sp. nov. GZNU20230216005 63.7 52.5 7.7 5.8 11.8 6.8 8.6 3.4 4.4 1.3 4.7 2.9 2.1 4.1 1.5 4.9 32.4 5.1 10.3 8.2 2.2 11.6 7.7 2.1 27.4 8.5 4.9 40.3 7.9 5.3 4.9 3.9 6.6
6 O. damingshanensis sp. nov. GZNU20230216006 73 59.9 8.7 6.2 13.3 7.3 9.8 4.3 5 0.9 5.2 3.2 2.8 4.8 1.5 5.6 36.2 6.6 11.7 10.3 2.4 12.9 10 2.2 30.7 10.7 5.2 45.3 9.7 6.4 6.5 5 8.3
7 O. damingshanensis sp. nov. GZNU20230216007 81.3 67.6 10.8 7.8 14.8 7.6 10.8 4.5 5.2 1 6.1 3.9 3.1 5.3 1.9 6.2 42.1 6.2 12.7 10.5 2.6 14.5 10.3 2.5 34.3 11.1 4.9 50.7 9.7 7.2 5.9 5.2 8.2
8 O. damingshanensis sp. nov. GZNU20230216008 75 62.2 8.8 7.2 13.2 7.5 9.5 3.1 4.5 0.9 5 3.1 2.4 5 1.5 4.6 37.6 6.5 10.7 9.8 2.5 13.6 9.1 2 30.7 10.5 5.2 46.9 10.1 6.7 6.7 4.6 7.5
9 O. damingshanensis sp. nov. GZNU20230216009 79.2 66.4 9.8 7.3 14.2 7.2 9.6 4 5 0.9 5.4 3.2 2.6 5.3 2 5.8 39.8 6 11.8 11.1 2.4 13.8 10.2 2.5 34.1 10.9 5.8 50.2 10.2 6.7 5.7 4.7 6.7
10 O. damingshanensis sp. nov. GZNU20230216010 77.2 62.8 10.3 7.4 14.4 8.1 11 4.3 5.1 1.1 6.1 3.8 2.7 5.7 1.7 6 38.6 6.4 11.2 10.7 2.7 14.3 9.8 2.2 32.3 10.6 5.4 48.9 9.3 7.1 5.5 5.2 7.1
11 O. damingshanensis sp. nov. GZNU20230216011 73 59.6 8.9 7 13.1 6.9 9.8 4 4.6 0.8 5.6 3.2 2.4 4.9 1.7 5.3 37.4 5.9 11.1 10 2.4 12.7 10 2.2 30.7 10.2 5.1 45 8 6.7 5.4 4.7 6.9
12 O. damingshanensis sp. nov. GZNU20230216012 74.3 61.3 10.2 7 13.2 7.4 9.8 4.1 4.5 0.8 5.5 3.1 2.6 4.6 1.7 5.7 38.3 5.6 11 10.6 2.7 13 9.4 2.4 31 9.4 4.7 46.8 9.8 6.7 6 4.1 6.4
13 O. damingshanensis sp. nov. GZNU20230216013 73.3 60.8 10.2 6.9 14.2 8.1 11.1 4.2 5.1 0.9 6.1 3.5 2.9 5.4 1.8 6 37.6 6.5 12 10.2 2.6 13.9 9.8 2.5 31.8 10.6 5.7 46.1 9.3 6.7 6.6 4.1 7.4
14 O. damingshanensis sp. nov. GZNU20230216014 64.6 52.9 8.2 5.9 12 6 8.2 3.4 4.1 0.6 4.7 2.9 2.4 4.4 1.6 4.7 31.8 5.3 10.1 10.3 2.3 11.9 8.5 2.1 28.4 9.8 4.5 40.1 8.6 5.7 5.8 4.3 6.3
15 O. damingshanensis sp. nov. GZNU20230216015 63.4 52.8 8 5.7 12.1 6.6 8.1 3.6 4.1 0.8 4.7 3.1 2.6 4.7 1.6 4.8 31 5 8.8 8.3 1.9 11.2 6.9 2.3 26.5 8.9 4.6 39.9 8 5.9 4.6 3.9 5.5
16 O. damingshanensis sp. nov. GZNU20230216016 77.8 64.1 9.7 8 14.1 7.9 10.7 4.5 4.9 0.6 5.8 3.1 2.6 5.2 1.9 6 38.7 6.3 12.5 10.6 2.5 13.7 10 2.6 31.8 10.7 5.5 49.6 9.8 6.9 7 5.4 8
17 O. damingshanensis sp. nov. GZNU20230216017 72.1 60.5 10.3 7.2 13.6 7.3 9.7 4.6 5 1 5.4 3.2 2.6 5.2 1.7 6 36.4 6.1 10.9 9.2 2.3 12.8 9.4 2.6 30.4 9.7 5.1 46.2 9.8 7.2 6.1 4.7 7.3
18 O. damingshanensis sp. nov. GZNU20230216018 72.6 59.5 9.1 6.4 14 7.5 10.7 4.1 4.6 0.7 5.7 3.4 2.4 5 2 5.5 35.9 5.8 10.6 10 2.4 13.7 9.3 2.6 31 10 5.6 45.6 8.1 6.5 5.5 4.2 6.9
19 O. damingshanensis sp. nov. GZNU20230216019 66.6 54.3 7.8 5.8 12.8 6.9 9.7 4.1 4.2 0.7 5.7 3.1 2.6 5 1.6 5.3 32.5 5.9 10.4 9.4 2.4 12.7 8.7 2.1 27.7 10.3 4.9 40.5 8.4 6.3 5.1 3.7 6.6
20 O. damingshanensis sp. nov. GZNU20230216020 78.9 64.1 8.9 6.3 13.7 7.5 10.6 3.5 4.7 1 5.9 3.6 2.8 5.7 1.9 5.4 37.5 6.6 11.9 10.2 2.6 14.4 10 2.4 33.3 10.8 5.6 49.2 10.3 7.3 6.6 4.5 6.6
21 O. damingshanensis sp. nov. GZNU20230216021 69.6 57 9.4 6.6 12.5 7.2 9.7 3.8 4.3 0.8 5.1 3.2 2.5 4.9 1.8 5.4 33.5 6.1 11.4 9.3 2.6 12.2 8.5 2.4 29.1 9.7 4.8 42 9.3 6.8 6.2 4.6 6.7
22 O. damingshanensis sp. nov. GZNU20230216022 59.1 47.8 7.1 5 10.6 5.5 7.7 3 3.6 0.7 4.5 3.1 0.3 3.7 1.4 4.5 27 5.5 10.8 8.3 2 10.1 8.1 1.5 23.8 9.4 4.2 35.2 8.4 4.9 6 3.9 5.4
23 O. damingshanensis sp. nov. GZNU20230216023 59.7 48.4 7.2 5.4 10.5 5.9 8.3 3.2 3.8 0.7 4.2 2.9 2.4 4.1 1.8 4.4 29.4 5.1 10 8.3 1.9 10.9 7.9 2 25.2 9.1 4.4 36.8 6.8 5 4.9 4 5.9
24 O. damingshanensis sp. nov. GZNU20230216024 60.5 48.9 7 5.3 10.8 5.7 8 3.4 4 0.7 4.5 3.1 2.3 4.1 1.7 4.5 27.8 5.6 10.4 8.7 1.9 10.5 7.7 1.9 24.1 9.4 5.2 35.8 6.9 5.2 4.4 4.1 5.6
25 O. damingshanensis sp. nov. GZNU20230216025 55.7 46.2 7 5 10.2 5.4 7.8 2.8 3.4 0.6 4.4 2.5 2.1 3.9 1.6 4.4 27.9 4.9 8.8 8.1 1.8 9.8 7.7 1.5 23.8 8.3 4.4 34.5 6.4 4.9 4.6 3.9 5.8
26 O. damingshanensis sp. nov. GZNU2020011505 91 76.7 12.5 8.3 16.5 8.8 9 3.8 6.1 1.1 6.9 3.6 2.7 4.8 1.3 7.7 45.9 9.1 13.9 12.2 3 17.3 12.2 2.5 40.6 13.3 7.2 57.5 10.5 8 6.6 5.6 7.1
27 O. damingshanensis sp. nov. GZNU2020011506 79 64.2 9.6 8 13.9 7 9.3 3.2 4.8 0.9 5.5 2.2 2.1 3.3 0.9 5.6 37.1 6.8 13 10 2.3 14.4 10 2.1 33.1 10.8 4.9 49.1 11 7.9 5 4.7 7.4
28 O. damingshanensis sp. nov. GZNU2020011507 80.3 67.8 11.5 4.6 15 7.4 9 3.7 5.1 0.8 6.8 2.7 2 4.4 1 6.9 39.3 6.7 10.7 11 2.6 14.5 11 2.6 34.3 10.8 5.5 51.6 9.1 7.1 6.6 5.2 6.9
29 O. damingshanensis sp. nov. GZNU2020011508 71.9 59.2 11 7.1 13.9 7.4 9.9 3.2 4.6 0.9 5.9 2.6 1.8 2.5 1 6.1 39.8 5.8 11.8 9.8 2.2 14.9 9.8 2.4 35.5 10.8 5.4 52.7 9 6.6 5.2 4.6 5.9
30 O. damingshanensis sp. nov. GZNU2020011509 72.8 61.4 7.9 7 12.1 6.1 8.7 3.1 5.2 0.8 5.1 2.8 2.1 3.6 1.7 6.9 36.4 5.1 10.8 9.9 2.6 12.5 9.9 2.4 30.7 10 4.7 46.1 9.2 7 6 3.5 5.3
31 O. platycephalus GZNU2020011510 52.2 51.1 6.3 4.8 10.5 5.8 7.6 2.7 4.5 0.9 3.9 1.7 1.5 2.9 1.7 5.7 31.3 4.1 9 8.6 2 10.9 8.8 1.9 26.1 8.6 4.1 38.2 8.6 6 4.8 3.2 5.1
32 O. platycephalus GZNU2020011511 52.3 41.8 6.4 4.7 9 4.3 6.2 1.9 3.4 0.9 3.3 1.8 1.4 2.4 0.8 4.6 24.9 3.9 7.3 7.8 1.9 9 8.2 1.9 21.5 7.6 3.4 32.1 6.5 4.9 4.3 3.3 4.4
33 O. platycephalus GZNU2020011512 53.5 44.4 6.3 3.6 9 4.6 6.5 2 3.9 0.8 3.8 1.8 1.4 2.9 0.8 4.6 27 3.5 7.3 6.9 1.8 9.5 7.3 1.4 21.1 7.6 3.5 33.5 7.3 4.6 1.8 3 4.3
34 O. platycephalus GZNU2020011513 53.5 44.4 6.3 3.6 9 4.6 6.5 2 3.9 0.8 3.8 1.8 1.4 2.9 1 4.6 27 3.4 7.3 6.9 1.8 9.5 7.3 1.4 21.1 7.6 3.5 33.5 7.3 4.6 3.6 3 4.3
35 O. platycephalus GZNU2020011514 41 33.1 4.6 2.8 6.6 2.9 4.5 1.7 2.3 0.6 1.9 1.2 0.9 1.6 0.5 3.7 19.7 2.1 4.9 5.1 1.3 7 5.3 1.2 16.8 4.8 2 24.4 5.6 3.5 2.7 1.5 3.4
36 O. platycephalus GZNU2020011515 85.5 73.6 12.2 7.6 16.7 6.5 9.1 3.8 6.1 1.5 7 3.5 2.4 4.1 1.9 8.2 43.1 6.4 9.9 10.8 2.7 17.6 11.1 2.6 39.3 8.7 5.2 56 11.1 7.6 6.2 5.5 8.1
37 O. guananensis GZNU2020050201 85.8 70 9 6.7 16 6.2 8.6 3.7 6.6 1.4 6.2 3.7 2.5 4.4 7.7 2 40.9 6.2 13.2 11.5 2.1 16.7 9.7 1.4 39.3 12 5 55.4 8.9 8.1 8.9 4.2 6.4
38 O. guananensis GZNU2020050202 64.3 53.9 7.9 4.6 11.5 3.3 6 2.6 4.3 1.4 4.4 2.5 1.9 2.6 5.3 2.1 31.4 4.7 9.7 5.3 1.8 12.1 6.1 0.8 28.6 7.8 3.5 40.6 7.6 5.5 7.2 4.3 8.8
39 O. guananensis GZNU2020050203 89 73.8 9.8 6.9 16.8 6.5 8.4 4 5.4 1.3 6.8 3.2 2.8 3.8 7.8 1.1 42.5 7.3 14.9 11 2.3 17.2 10.2 1.9 40.4 11.5 5.1 57.2 9 7.6 7.5 7 9.1
40 O. guananensis GZNU2020050204 50.5 40.6 5.7 4.2 8.9 3.5 4.3 1.8 3.7 1.2 3.6 1.7 1.5 2 4.3 1.6 24.8 2.5 7.2 6.6 1.1 9.6 5.5 0.8 22.9 6.7 3.4 32.7 7.1 4 4.9 3.4 5.5
41 O. guananensis GZNU2020050205 52.6 45 4.5 5.8 5.1 4.2 7.9 2.2 2.6 1.8 4.6 2 1.9 2.8 3.7 1.6 22.5 4.5 9.5 9.3 1.8 12.1 8.5 0.9 23.3 7.1 3.8 35.7 8.1 3.4 3.6 2.2 4.2
42 O. anophthalmus GZNU20190810 32 27.2 3.2 2.9 6 2.5 4 0 0 0 - 1.2 1.1 1.9 0 0 17.9 2.5 4.4 4 20.3 4.4 3 0.8 15 3.6 1.9 20.3 4.6 2.4 3.4 2 3.5
43 O. anophthalmus GZNU20190811 26.8 22.1 2.7 1.9 5.2 2 3.1 0 0 0 - 1.5 1.1 0.3 0 0 12.6 2.3 3.1 3.2 0.9 5.5 2.9 0.8 13.2 3.7 1.5 16.8 3.5 1.6 1.7 0.8 2.1
44 O. anophthalmus GZNU20190812 26.4 23.1 2.8 2 5.3 2.3 3.4 0 0 0 - 1.1 1.1 1.8 0 0 14.6 1.8 2.9 3 0.7 5.7 2.3 65 12.7 2.7 1.5 17.3 3 2.1 1.1 0.7 1.7
45 O. polystigmus GZNU201908004 66.4 55.5 9.5 8.7 11.9 7.8 8.1 2.8 5.1 1.1 4.4 2.3 1.9 2.9 0.8 6.3 33 4.4 9.7 9.3 2.4 12.6 8 1.7 30.3 7.6 3.9 44.7 9.9 5.9 6.9 4.4 6
46 O. polystigmus GZNU201908005 61.5 51.2 6 5.5 10.2 5.7 7.4 2.4 4.2 1.2 10.7 2.1 1.5 2.6 0.8 5 29.6 5 9.5 8.8 2.3 11.1 7.1 1.7 26.1 8 3.9 38.1 9 4.4 5.2 5 8.1
47 O. polystigmus GZNU201908006 66.9 54.6 8.3 6.1 11.6 6.3 7.6 2.6 4.3 1.2 4.6 2.2 1.8 3.3 1 6.2 31.8 4.7 9 9 1.6 11.5 7.2 1.4 29.8 8.1 3.9 43.4 9.6 5.1 5.6 4.4 6.7
48 O. polystigmus GZNU201908007 66.4 55.3 11.4 7.5 12.5 7.3 7.6 2.9 4.3 1 4.7 2.6 1.6 3.6 1.1 6.8 33.2 5.9 9.6 9.3 2.7 12.8 7.8 1.6 29.1 8.6 5 43 6.5 5.8 6 6.1 7
49 O. luochengensis GZNU2017001 80.6 65.6 9.3 9.4 13.2 6.5 7.6 3.3 3.1 1.4 5.5 2.5 2.3 4 6.6 2.1 38.2 6.2 11 11.9 2.2 15.1 8.9 1.7 36.2 9.4 4.3 53.6 7.4 6.1 5.2 4.5 7.4
50 O. luochengensis GZNU2017002 80.3 66.2 8.7 7 13 7.3 7.4 3 3.8 1.2 4.5 2.9 2.4 3.8 6.4 2.2 37.5 6.2 12.3 11.4 2.8 13.3 8.9 2 35.1 9.9 5.7 30.7 7.3 6.4 6.7 4.7 6.5
51 O. luochengensis GZNU2017003 61.7 51.7 7.3 6.3 10.6 5.6 6.1 2.3 3.3 1.1 7.7 2.5 1.8 3.1 5.7 1.6 29.8 4.1 9.5 9.2 1.6 11.4 11.4 1.6 28.5 8.4 3 40.7 8.1 5.7 5.1 3.7 5.1
52 O. luochengensis GZNU2017004 69.6 57.7 6.2 6.3 11.9 6.8 7 2.7 4.8 1.2 4.6 2.9 2.5 3.6 5.9 1.7 31.8 5.1 10.5 10 1.8 12.4 7.8 1.7 31.3 7.8 2 43.7 7.2 4.7 6.8 3.6 6.2
53 O. luochengensis GZNU2017005 68.3 56.4 9 6.9 11.9 6.4 5.6 3.2 4.4 1.3 4.1 2.3 2.1 3.8 5.5 1.8 33.9 4.4 9.4 7.9 1.7 12.4 6.6 1.6 29.9 7.5 4.3 42.5 6.8 5.1 5.2 3.6 4.5

Appendix 4

Table A2.
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Results and percentage of variance explained by principal component and discriminant function analyses.

Morphometric characters PC 1 PC 2 CAN1 CAN2
Total length 0.98 0.09 2.16 1.52
Standard length 0.98 0.13 -1.32 2.51
Body depth 0.91 0.16 0.66 3.09
Body width 0.89 0.10 -1.12 0.33
Head length 0.98 0.04 22.67 -4.69
Head depth 0.95 -0.03 -1.73 2.03
Head width 0.93 -0.23 0.06 -1.33
Distance between anterior nostrils 0.89 -0.33 0.83 0.33
Distance between posterior nostrils 0.93 0.23 2.20 0.78
Distance between anterior and posterior nostrils 0.48 0.62 0.11 1.50
Snout length 0.81 0.13 -1.95 0.66
Upper jaw length 0.87 -0.36 -3.74 -1.86
Lower jaw length 0.64 -0.19 2.36 -0.33
Mouth width 0.80 -0.50 -4.36 -1.40
Eye diameter 0.66 -0.61 5.74 3.13
Interorbital distance 0.78 0.48 -5.59 -0.07
Predorsal length 0.97 0.12 0.90 -7.80
Dorsal-fin base length 0.95 -0.11 7.66 -2.70
Dorsal-fin length 0.93 -0.13 -1.88 -3.96
Pectoral-fin length 0.96 0.02 -10.35 -0.52
Pectoral-fin base length 0.91 0.05 4.64 0.35
Prepectoral length 0.96 0.17 -7.18 5.32
Pelvic-fin length 0.91 0.05 9.18 2.90
Pelvic-fin base length 0.87 -0.19 1.26 -0.68
Prepelvic length 0.96 0.20 -4.10 -1.20
Anal-fin length 0.90 -0.21 2.49 2.53
Anal-fin base length 0.92 -0.19 -5.68 -0.58
Preanal length 0.97 0.19 -1.43 -0.16
Caudal peduncle length 0.83 0.26 3.97 0.70
Caudal peduncle depth 0.93 0.02 -8.64 -0.11
Maxillary barbel length 0.80 -0.02 -1.94 -0.86
Inrostral barbel length 0.81 0.09 -5.46 1.74
Outrostral barbel length 0.88 0.03 / /
Eigenvalues 28.91 0.04 71.51 22.45
Percentage of total variance 77.92 6.17 75.80 24.20
Cumulative percentage 77.92 84.09 75.80 100.00
Positive correlation / / 0.99 0.98
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