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Research Article
A new species of Opsariichthys (Teleostei, Cypriniformes, Xenocyprididae) from Southeast China
expand article infoXin Peng‡, Jia-Jun Zhou§|, Hong-Di Gao§, Jin-Quan Yang‡
‡ Shanghai Ocean University, Shanghai, China
§ Zhejiang Forest Resource Monitoring Center, Hangzhou, China
| Zhejiang Forestry Survey Planning and Design Company Limited, Hangzhou, China

Corresponding author: Hong-Di Gao ( ghd1118@163.com )

Corresponding author: Jin-Quan Yang ( jqyang@shou.edu.cn )

Academic editor: Tihomir Stefanov
© 2024 Xin Peng, Jia-Jun Zhou, Hong-Di Gao, Jin-Quan Yang.
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: Peng X, Zhou J-J, Gao H-D, Yang J-Q (2024) A new species of Opsariichthys (Teleostei, Cypriniformes, Xenocyprididae) from Southeast China. ZooKeys 1214: 15-34. https://doi.org/10.3897/zookeys.1214.127532
ZooBank: urn:lsid:zoobank.org:pub:3FD216F8-83BF-448A-A32B-AAB9099D75BD
Open Access

Abstract

Opsariichthys iridescens sp. nov. is described from the Qiantang and Oujiang rivers in Zhejiang Province and a tributary of the Yangtze River adjacent to the Qiantang River. It is distinguished from congeners by the following combination of morphological features: no obvious anterior notch on the tip of the upper lip; 45–52 lateral-line scales; 18–21 pre-dorsal scales; two rows of pharyngeal teeth; a maxillary extending to or slightly beyond the vertical anterior margin of the orbit in adult males; a pectoral fin extending to the pelvic fin in adult males; nuptial tubercles on the cheeks and lower jaw of males, which are usually united basally to form a plate; uniform narrow pale pink cross-bars on trunk and two widening significantly on caudal peduncle. Its validity was also supported by its distinct Cyt b gene sequence divergence from all congeners and its monophyly recovered in a Cyt b gene-based phylogenetic analysis.

Key words

Cytochrome b, morphology, opsariichthine, phylogenetic analysis, principal component analysis (PCA), taxonomy

Introduction

The genus Opsariichthys Bleeker, 1863, are a group of small-sized cyprinid fishes endemic to East Asia that live in fast-flowing rivers or streams (Chen 1982; Chen and Chang 2005; Wang et al. 2019). The type species, Opsariichthys uncirostris (Temminck & Schlegel, 1846), was initially described from Japan and assigned to the genus Leuciscus Cuvier, 1816. Since the genus Opsariichthys was first established, its earliest members, such as Zacco Jordan & Evermann, 1902 and Candidia Jordan & Richardson, 1909, that belonged to the so-called opsariichthine group and have large and elongated anal fins and a series of nuptial tubercles on the jaws as common adult features (Chen 1982), have been placed in this genus, and a total of 27 species have been described over the last one hundred years or more (Fricke et al. 2024). Chen (1982) taxonomically defined the opsariichthine fishes and noted that Opsariichthys included only two species, among which O. uncirostris was distributed in Japan and the other species, O. bidens Günther, 1873, was distributed in East Asia. Chen and Chu (1998) continued to follow this opinion.

Both morphological and molecular studies have shown that Opsariichthys and Zacco are closely related genera (Bǎnǎrescu 1968; Chen 1982; Huang et al. 2017; Wang et al. 2019; Zhang et al. 2023), and the traditional morphological features that distinguishes these two genera are that the former have a conspicuous notch on the tip of their upper lip and undulated jaws, while the latter has no obvious notch on the tip of their upper lip and relatively straight jaws (Jordan and Evermann 1902; Bǎnǎrescu 1968; Chen 1982; Chen and Chu 1998). However, recent molecular studies have revealed distinct genetic differentiation and multiple genetic lineages within O. bidens and Z. platypus (Temminck & Schlegel, 1846), which may correspond to different species based on traditional diagnostic features (Berrebi et al. 2005; Perdices et al. 2004; 2005). Furthermore, the genetic lineages of both species are paraphyletic (Perdices and Coelho 2006). These two species are sympatric in many places and are considered widespread in East Asia (Wang et al. 2019).

Subsequently, based on the results of morphological and phylogenetic studies, Chen et al. (2009) proposed new diagnostic key features of these two genera, suggesting that the nuptial tubercles on the cheeks of male Opsariichthys were separated and that the pale green lateral cross-bars were clear and independent, while the nuptial tubercles on the cheeks of male Zacco were united basally to form a plate and that the lateral pale green cross-bars were fused into fewer large patches. A phylogenetic study based on the mitochondrial genome by Huang et al. (2017) reaffirmed that the lateral cross-bars were a key diagnostic feature in the taxonomy of the opsariichthine group. This view has now been widely accepted. Based on this new classification, the following four new species are described: O. songmaensis Nguyen & Nguyen, 2000; O. dienbienensis Nguyen & Nguyen, 2000; O. kaopingensis Chen & Wu, 2009; and O. duchuunguyeni Huynh & Chen, 2013. Three species, viz., O. acutipinnis (Bleeker, 1871), O. evolans (Jordan & Evermann, 1902), and O. macrolepis (Yang & Hwang, 1964), formerly known as Z. platypus, are reinstated as valid Opsariichthys species. Three species, viz., O. amurensis Berg 1932, O. minutus Nichols, 1926, and O. hainanensis Nichols & Pope, 1927, that were once considered to be synonymous with O. bidens are also revalidated. Two species, O. chengtui (Kimura 1934) and O. pachycephalus (Günther 1868), are transferred from Zacco to Opsariichthys, while the taxonomic status of two other species, O. bea Nguyen 1987 and O. hieni Nguyen 1987, remains uncertain (Fricke et al. 2024). Therefore, Opsariichthys is currently considered to include 14 valid species, eight of which are distributed across mainland China. The valid species in mainland China are O. acutipinnis, O. amurensis, O. bidens, O. chengtui, O. evolans, O. hainanensis, O. macrolepis, and O. minutus, and with the exception of O. bidens, are all regionally distributed species.

While examining Opsariichthys specimens collected from Zhejiang Province and the tributaries of the Yangtze River adjacent to the Qiantang River, we found that some of the specimens did not belong to any described species. Further morphological and molecular analyses of these specimens support that they belong to a new species, which we describe here.

Materials and methods

Sample collection and morphological analysis

Sixteen specimens were collected from the Qiantang River system in Lin’an District, Hangzhou City, and Suichang County, Lishui City, Zhejiang Province, as well as from the Qiantang River region in She County, Huangshan City, Anhui Province. The right pectoral fins of these freshly collected specimens were preserved in 95% ethanol for molecular biology analyses. Meanwhile, specimens with left fins were fixed in 10% formalin for three days and then transferred to 70% ethanol for long-term preservation and subsequent morphological analyses. The specimens used in the present study were deposited at Shanghai Ocean University, Shanghai, China (SHOU). Two species (O. bidens and O. evolans) were used for deep morphological comparison with the new species because their sympatric distribution (Fig. 1). Data of other similar Opsariichthys species for comparison were cited from literatures (Yang and Huang 1964; Chen et al. 2009; Huynh and Chen 2013; Wang et al. 2019).

Figure 1. 

Map showing sampling sites of O. iridescens sp. nov. and its two sympatric species that were examined in the present study.

The morphometric measurements and meristic counts generally followed those of Chen et al. (2009) and Huynh and Chen (2013). Morphometric characteristics were measured with digital calipers and recorded to the nearest 0.1 mm. Counts and measurements were made on the left side of the specimen. The meristic abbreviations are as follows: D, dorsal fin; A, anal fin; P1, pectoral fin; P2, pelvic fin; LL, lateral-line scales; LLa, scales above the lateral line; LLb, scales below the lateral line; PreD, predorsal scales; and CPS, circum-peduncular scales. All the fish were measured for standard length (SL).

Based on the morphological data, principal component analysis (PCA) was performed on the three Opsariichthys species using R software. From the cumulative contribution of the principal components, the scores of the first principal component (PC1) and the second principal component (PC2) were plotted. Canonical discriminant analysis (CDA) and graphing were performed using SPSS version 23.0.

DNA extraction, PCR amplification, and sequencing

Genomic DNA was extracted using an animal genomic DNA extraction kit from Shanghai Sangon Biotech Co., Ltd. The cytochrome b gene (Cyt b) was amplified using polymerase chain reaction (PCR) with the primers L14724 (5’-GACTTGAAAAACCACCGTTG-3’) and H15915 (5’-CTCCGATCTCCGGATTACAAGAC-3’) (Xiao et al. 2001). Each 25 μL of PCR reaction mixture contained 1 μL of DNA template, 1 μL of each primer, 12.5 μL of Taq PCR Mix (Sangon Biotech Co., Ltd., Shanghai, China), and 9.5 μL of ddH2O. The PCR conditions were as follows: pre-denaturation at 95 °C for 3 min; denaturation at 94 °C for 30 s; annealing at 54 °C for 40 s; extension at 72 °C for 1 min; 35 cycles of extension at 72 °C for 5 min; and heat preservation at 4 °C. After the PCR reaction was completed, the products were detected by agarose (1.5%) electrophoresis and sequenced bidirectionally by Shanghai Sangon Biotech Co., Ltd. The sequencing results for the Cyt b sequences were manually corrected and assembled using SeqMan software from DNASTAR (Burland 2000).

Phylogenetic analysis

A total of 74 sequences were used, 45 of which were newly sequenced and 29 of which were obtained from GenBank. The specific sample information is shown in Table 1. MEGA v. 11.0 (Tamura et al. 2021) was used to align the sequences and calculate the nucleotide composition, variable sites, parsimony informative sites and genetic distances between species. Neighbor joining (NJ) analysis was also performed with MEGA v. 11.0 using the Kimura 2-parameter (K2P) model. Bootstrapping with 1,000 pseudo replicates was used to examine the robustness of the clades in the resulting tree. The best substitution model (TIM2+I+G) was selected for maximum likelihood (ML) analysis and Bayesian inference (BI) analysis using jModeltest v. 2.0 software (Darriba et al. 2012) with the Akaike information criterion (AIC). ML analysis was conducted using IQ-TREE v. 2.0 software (Minh et al. 2020), and node confidence was analyzed by bootstrap analysis with 1,000 repetitive samples. Mrbayes v. 3.2.6 software (Ronquist et al. 2012) was used to conduct the BI analysis, and posterior probability was used to indicate the credibility of each branch. The starting tree was set as a random tree. Four Markov chains were run simultaneously for two million generations, with three hot chains and one cold chain. The system tree was sampled every 100 generations to remove the top 25% of untrustworthy regions, and the process was stopped when the variance of convergence was less than 0.01. All trees were viewed and edited using FigTree v. 1.4.3 software (Rambaut 2016).

Table 1.
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The samples used in this study with their localities, voucher information, and GenBank accession numbers.

Genus Species Location River Voucher number GenBank accession number
Opsariichthys O. iridescens sp. nov. Lin’an, Zhejiang Qiantang River ZJQT01-05 PP639122–PP639123, PP639130–PP639132*
Huangshan, Anhui Qiantang River ZJXA01-03 PP639124–PP639126*
Wuyuan, Jiangxi Yangtze River ZJLA01-03 PP639127–PP639129*
Lishui, Zhejiang Ou River ZJOJ01-03 PP639133–PP639135*
O. bidens Lin’an, Zhejiang Qiantang River MKQT01-02 PP639101–PP639102*
Dongyang, Zhejiang Qiantang River MKQT03 PP639103*
Shengzhou, Zhejiang Cao’e River MKCE PP639097*
Yichun, Jiangxi Gan River MKJJ01-03 PP639098–PP639100*
Fujian Jiulong River OBJLJ1-2 FJ602005–FJ602006
O. evolans Lin’an, Zhejiang Qiantang River CQQT01-02 PP639110–PP639111*
Dongyang, Zhejiang Qiantang River CQQT03-07 PP639112–PP639116*
Quzhou, Zhejiang Qiantang River ZP_QTJ_1-2 MH350437–MH350438
Shangyu, Zhejiang Cao’e River CQCE01 PP639104*
Shengzhou, Zhejiang Cao’e River CQCE02-06 PP639105–PP639109*
Lishui, Zhejiang Ou River CQOJ01-02 PP639117–PP639118*
Taiwan Unknown OETaiW1-2 KR698567–KR698568
O. macrolepis Hejiang, Sichuan Yangtze River ZP_CJU2_1 MH350702
O. hainanensis Hainan Unknown OHAND2 KJ940933
O. chengtui Chengdu, Sichuan Yangtze River – KT725244
O. acutipinnis Huangshan, Anhui Yangtze River ZPQimen4 KM491719
O. duchuunguyeni Baise, Guangxi Pear River ZPPE_You1 KP101024
O. pachycephalus Taiwan Unknown OPTaiW1 KR698649
O. kaopingensis Taiwan Unknown – AY958189
O. minutus Guangxi Pear River OMhap01 KR698540
O. uncirostris Japan Unknown OUJapan1 KR698682
Opsariichthys sp. A Huangshan, Anhui Yangtze River ZPTaiping2 KM491721
Opsariichthys sp. B Fujian Min River OEMinJ1 KR698572
Opsariichthys sp. C Hunan Yangtze River OEXiangJ5 KR698575
Opsariichthys sp. D Jiangxi Yangtze River ZA_FH2 MH350668
Opsariichthys sp. E Hunan Yangtze River OELI1 KR698563
Zacco Z. acanthogenys Shengzhou, Zhejiag Qiantang River JJQT01-03 PP639119–PP639121*
Z. tiaoxiensis Yuhang, Zhejiang Tiaoxi River TX01-03 PP639136–PP639138*
Z. sinensis Fengcheng, Liaoning Yalu River ZHYL01-03 PP639139–PP639141*
Z. platypus Japan Miya River ZPWJ1 LC019793
Parazacco P. spilurus Unknown Unknown PS1 KF971863
P. fasciatus Unknown Unknown PF1 AY958195
Nipponocypris N. temminckii Unknown Unknown NT1 EF452750
N. sieboldii Unknown Unknown NS1 AY958198
Candidia C. barbatus Taiwan Fenggang River CB1 AY958200
C. pingtungensis Taiwan Gaoping River CP1 KT725246
Aphyocypris A. chinensis Japan Unknown – NC008650
A. chinensis China Unknown – AF307452

Note: * Sequenced in this study.

Results

Taxonomic account

Family Xenocyprididae Günther 1868

Genus Opsariichthys Bleeker, 1863

Opsariichthys iridescens Peng, Zhou & Yang, sp. nov.

https://zoobank.org/FADF08EA-9DBC-45A3-9D67-79274C1B3083
Figs 2, 3A, B

Type material

Holotype • SHOU202210001, male, adult, 91.0 mm standard length (SL), collected by Jia-Jun Zhou and Hui Cao in October 2022, in Lin’an District, Hangzhou City, Zhejiang Province (Qiantang River) (30.2368°N, 119.7196°E). Paratypes • SHOU202210002–SHOU202210010, 9 specimens, 79.1–96.0 mm standard length (SL), collected by Jia-Jun Zhou and Hui Cao in October 2022, from the same locality as the holotype; SHOU202106089, SHOU202106090, and SHOU202106125, 3 specimens, 85.7~110.7 mm standard length (SL), collected by Jia-Jun Zhou and Wei Sun in June 2021, in Suichang County, Lishui City, Zhejiang Province (Qiantang River) (28.5956°N, 119.2709°E); SHOU202106001–SHOU202106003, 3 specimens, 84.5~109.4 mm standard length (SL), collected by Yun-Feng Huang in June 2021, in Shexian County, Huangshan City, Anhui Province (Qiantang River) (29.8637°N, 118.4100°E).

Diagnosis

The new species, Opsariichthys iridescens sp. nov. can be clearly distinguished from its two sympatric congeners in the Qiantang River and nearby geographic regions (Tables 3, 4). It can be distinguished from O. evolans by the following features: (1) lateral-line scales 45–52 (vs 42–45); (2) scales above lateral-line nine or ten (vs 8); (3) pre-dorsal scales 18–21 (vs 15–17); (4) two rows of pharyngeal teeth (vs 3 rows); (5) maxillary extending to or slightly beyond the vertical of anterior margin of orbit in adult male (vs never extending to the vertical of anterior margin of orbit); (6) pectoral fin extending to pelvic fin in adult male (vs extending far beyond origin of ventral fin); (7) almost uniform narrow pale cross-bars on trunk and widening significantly on caudal peduncle (vs gradually widened, Fig. 3E, F); (8) lower jaw with one row of large tubercles usually united basally to form a plate in male (vs 1 row of moderate tubercles well separated). The new species can be clearly distinguished from O. bidens by the following features: (1) absence of distinct anterior notch on upper lip (vs presence of conspicuous anterior notch on upper lip); (2) two rows of pharyngeal teeth (vs 3 rows); (3) maxillary extending to or slightly beyond the vertical of anterior margin of orbit in adult male (vs extending to the vertical midpoint of the eye); (4) pectoral fin extending to pelvic fin in adult male (vs never extending); (5) almost uniform narrow pale cross-bars on trunk and widening significantly on caudal peduncle (vs gradually widened, Fig. 3C, D); (6) one row of large tubercles under lower jaw united basally to form a plate in male (vs 3 or 4 rows of moderate tubercles well separated).

Opsariichthys iridescens sp. nov. can be well separated from the congeners: O. uncirostris from Japan and Korea; O. amurensis, O. minutus, and O. hainanensis from mainland China; O. dienbienensis and O. songmaensis from Vietnam, like O. bidens, by the absence of distinct anterior notch on upper lip (vs the presence of distinct anterior deep notch on that). Besides O. evolans, the new species can be distinguished from the remaining congeneric species: O. acutipinnis, O. chengtui, and O. macrolepis from mainland China; O. kaopingensis and O. pachycephalus from Taiwan; O. duchuunguyeni from Vietnam, that have an absence of distinct anterior notch on upper lip as well as by the following combination of morphological features (Table 4): (1) lateral-line scales 45–52; (2) scales above lateral line nine or ten; (3) pre-dorsal scales 18–21; (4) circum-peduncular scales 16 or 17; (5) two rows of pharyngeal teeth; (6) maxillary extending to or slightly beyond vertical of anterior margin of orbit in adult male; (7) pectoral fin extending to pelvic fin in adult male; (8) almost uniform, narrow, pale cross-bars on trunk, widening significantly on caudal peduncle; (9) nuptial tubercles on cheeks and lower jaw united basally to form a plate in adult male.

Description

The morphometric and meristic data are listed in Tables 2, 3. Fig. 2A, B shows lateral views of the male and female fish.

Figure 2. 

Opsariichthys iridescens sp. nov. A holotype, SHOU202210001, preserved male specimen, 91.0 mm SL B paratype, SHOU202308012, preserved female specimen, 85.2 mm SL.

Figure 3. 

Opsariichthys iridescens sp. nov. A live male B live female; Opsariichthys bidens C live male D live female; Opsariichthys evolans E live male F live female.

Table 2.
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Morphometric measurements of Opsariichthys bidens, O. evolans, and O. iridescens sp. nov.

O. bidens O. evolans O. iridescens sp. nov.
Male Female Male Female Holotype Male Male Female
n 2 8 9 8 1 13 2
Standard length (mm) 95.2~100.6 76.1~131.6 71.2~111.6 67.5~84.0 91.0 79.1~110.7 84.5~92.4
% of SL Min Max Mean Min Max Mean Min Max Mean Min Max Mean Min Max Mean Min Max Mean
Body depth 24.6 26.8 25.7 20.1 25.2 22.5 22.1 25.5 24.2 22.0 24.8 23.8 24.0 23.7 28.6 26.0 23.3 24.7 24.0
Head length 30.0 30.1 30.0 29.8 31.1 30.5 23.4 26.5 24.8 24.2 26.6 25.3 27.2 25.8 27.9 27.1 26.5 27.2 26.9
Length of the caudal fin peduncle 17.3 18.2 17.7 14.6 20.0 16.5 16.3 19.3 17.6 16.2 19.5 17.9 18.5 17.1 20.1 18.7 17.6 18.1 17.9
Depth of the caudal fin peduncle 9.0 9.5 9.2 8.2 9.9 8.8 7.7 9.4 8.7 8.2 9.3 8.8 9.2 8.5 10.0 9.3 8.5 8.8 8.7
Dorsal fin length 18.7 18.9 18.8 14.1 17.4 15.8 19.3 26.0 23.3 17.8 24.9 20.9 17.2 17.0 19.8 18.2 16.5 16.8 16.7
Pectoral fin length 19.6 22.0 20.8 12.9 19.8 17.9 24.6 30.9 27.3 19.4 28.5 24.2 23.1 21.1 26.7 23.5 18.4 19.1 18.8
Pelvic fin length 15.3 16.2 15.7 11.7 14.8 13.6 16.8 22.2 19.3 13.9 19.7 17.3 15.5 14.2 17.8 15.5 12.8 14.5 13.7
Anal fin length 25.6 28.5 27.0 18.3 25.1 21.8 33.3 42.4 38.2 22.6 39.7 31.5 29.3 28.0 35.7 32.1 25.7 25.8 25.8
Dorsal fin base length 13.0 13.3 13.2 9.3 11.4 10.6 12.1 15.2 13.5 10.0 14.9 12.1 12.3 11.6 13.4 12.5 10.2 10.7 10.5
Pectoral fin base length 4.5 5.1 4.8 3.3 4.4 3.9 4.6 5.9 5.3 4.0 5.1 4.6 5.1 5.0 6.3 5.8 4.0 4.2 4.1
Pelvic fin base length 3.7 3.8 3.7 3.2 4.0 3.6 3.3 4.5 3.8 3.2 4.6 3.8 4.9 3.8 4.9 4.2 3.6 3.7 3.7
Anal fin base length 15.1 15.4 15.3 10.5 12.0 11.0 15.6 18.9 17.2 13.6 19.1 15.6 17.6 15.2 18.6 16.9 12.6 13.2 12.9
Predorsal length 53.2 53.3 53.2 51.8 56.2 53.8 48.4 50.0 48.9 48.3 50.5 49.2 51.1 49.0 55.2 51.9 51.3 54.0 52.7
Prepectoral length 26.8 27.0 26.9 27.5 29.6 28.9 23.6 25.7 24.5 23.9 27.7 25.0 24.5 24.5 26.8 25.6 26.5 26.8 26.7
Prepelvic length 50.1 52.0 51.1 51.6 54.8 53.0 46.1 49.5 47.3 46.4 50.2 48.3 46.3 46.3 49.9 48.0 49.8 50.0 49.9
Preanal length 68.9 69.3 69.1 71.2 73.9 72.6 46.6 68.6 65.1 66.6 71.5 69.1 63.1 63.1 70.4 66.2 69.4 71.2 70.3
% of HL
Snout length 29.3 32.1 30.7 29.6 33.7 32.1 25.7 33.4 29.0 27.6 31.5 29.3 31.4 28.8 35.6 31.5 29.7 30.8 30.3
Eye diameter 18.2 19.6 18.9 16.0 22.4 19.1 21.9 30.5 27.0 25.5 28.4 27.5 20.4 20.4 29.3 25.4 26.5 27.8 27.2
Interorbital width 31.7 31.9 31.8 28.2 31.4 29.7 29.5 34.7 31.4 26.1 34.4 30.7 34.3 32.0 37.1 34.8 30.9 32.5 31.7
Head depth 64.0 66.2 65.1 56.4 62.6 59.4 69.7 78.7 74.5 64.1 76.5 68.6 69.5 67.2 75.6 70.6 66.2 67.0 66.6
Head width 49.0 54.3 51.6 38.9 49.5 43.9 44.5 52.3 49.5 42.1 54.1 49.0 48.5 45.4 55.8 51.0 49.1 52.9 51.0
Table 3.
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Meristic counts of the three sympatric Opsariichthys species and its congeners that absence of distinct anterior notch on upper lip.

Species D iii A iii P1 i P2 i
7 8 M 8 9 10 M 13 14 15 M 7 8 M
O. iridescens sp. nov. 16 – 7.0 – 16 – 9.0 1 15 – 13.9 2 14 7.9
O. bidens 10 – 7.0 1 9 – 8.9 – 10 – 14.0 – 10 8.0
O. evolans 17 – 7.0 – 16 1 9.1 1 15 1 14.0 3 14 7.8
O. acutipinnis* 9 – 7.0 – 9 – 9.0 – 1 8 14.9 – 9 8.0
O. duchuunguyeni* 5 – 7.0 – 5 – 9.0 – 4 1 14.2 1 4 7.9
O. kaopingensis* 118 – 7.0 3 115 – 9.0 5 147 72 14.3 210 14 8.1
O. macrolepis* 30 – 7.0 – 30 – 9.0 – 30 – 14.0 15 15 7.5
O. pachycephalus* 421 2 7.0 17 398 12 9.0 251 251 38 13.6 251 123 8.3
CPS LLa LLb
16 17 18 19 20 M 8 9 10 11 M 3 4 5 M
O. iridescens sp. nov. 5 11 – – – 16.7 – 7 9 – 9.6 3 13 – 3.8
O. bidens – 2 7 1 – 17.9 – 10 – – 9.0 3 6 1 3.8
O. evolans 10 7 – – – 16.4 17 – – – 8.0 3 14 – 3.8
O. acutipinnis* – – 2 6 1 18.9 2 7 – – 8.8 1 8 – 3.9
O. duchuunguyeni* – 4 1 – – 17.2 5 – – – 8.0 5 – – 3.0
O. kaopingensis* – 1 1 1 1 18.5 – 95 17 – 9.2 104 7 – 3.1
O. macrolepis* – 15 15 – – 17.5 30 – – – 8.0 30 – – 3.0
O. pachycephalus* – 1 4 3 5 18.9 – – 251 38 10.1 251 20 – 3.1
PreD
13 14 15 16 17 18 19 20 21 22 23 M
O. iridescens sp. nov. – – – – – 2 5 7 2 – – 19.6
O. bidens – – – – – – 3 5 2 – – 19.9
O. evolans – – 2 10 5 – – – – – – 16.2
O. acutipinnis* – – 1 5 3 – – – – – – 16.2
O. duchuunguyeni* 1 4 – – – – – – – – – 13.8
O. kaopingensis* – – – – 7 47 60 – – – – 18.6
O. macrolepis* – – – – 12 9 9 – – – – 17.9
O. pachycephalus* – – – – – – – 90 139 89 25 21.1
LL
41 42 43 44 45 46 47 48 49 50 51 52 53 54 M
O. iridescens sp. nov. – – – – 1 2 1 4 4 1 1 2 – – 48.6
O. bidens – – – – 2 6 2 – – – – – – – 46.0
O. evolans – 1 7 3 6 – – – – – – – – – 43.8
O. acutipinnis* – 7 2 – – – – – – – – – – – 42.2
O. duchuunguyeni* 5 – – – – – – – – – – – – – 41.0
O. kaopingensis* – – – 13 84 66 57 2 – – – – – – 45.8
O. macrolepis* – – – – – 15 10 4 1 – – – – – 46.7
O. pachycephalus* – – – – – – – 2 59 121 129 137 120 108 51.7

M: mean of all listed values; *: data cited from the literature.
Table 4.
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Morphological differences among eight Opsariichthys species that absence of distinct anterior notch on upper lip.

Character O. iridescens sp. nov. O. evolans O. acutipinnis* O. chengtui* O. duchuunguyeni* O. kaopingensis* O. macrolepis* O. pachycephalus*
Lateral-line scales 45–52 42–45 42–43 60–67 41 44–48 46–49 48–54
Scales above the lateral line 9–10 8 8–9 11 8 9–10 8 10–11
Predorsal scales 18–21 15–17 15–17 25–26 13–14 17–19 17–19 20–23
Circum-peduncular scales 16–17 16–17 18–20 21–22 17 17–20 17–18 17–20
Pharyngeal teeth 2 rows 3 rows 3 rows 2 rows 3 rows 3 rows 2 rows 3 rows
Whether the maxillary extending the vertical of anterior margin of orbit Extending to or slightly beyond Not reaching to or slightly extending Extending Extending Extending to or slightly beyond Reaching or slightly beyond Not reaching Extending to or beyond the middle vertical of orbit
Whether the pectoral extends to the origin of the pelvic fin Slightly extending Extending far beyond Never reaching Never reaching Not reaching or slightly extending Never reaching Not reaching or slightly extending Never reaching
Features of the bright bars on the flanks Uniform and narrow on the trunk and widening significantly on the caudal peduncle Gradually widened Gradually widened Gradually widened Gradually widened Uniform on the trunk and wider on the caudal peduncle Gradually widened Gradually widened
The number of tubercles on the lower jaw of adult males 1 row, united basally to form a plate in males 1 row, well separated 1 row, well separated 1 row, well separated 2 rows, well separated 1 row, well separated 2 or 3 rows, well separated 1 row, well separated

*: data cited from literature.

Dorsal fin rays iii, 7; anal fin rays iii, 9; pectoral fin rays i,13–14; pelvic fin rays i,7–8; lateral-line scales 45–52; scales above lateral line nine or ten; scales below lateral line three or four; predorsal scales 18–21; circum-peduncular scales 16 or 17; and two rows of pharyngeal teeth.

Body elongated and laterally compressed, belly rounded. Body depth slightly shorter than head length. No maxillary or rostral barbels. Mouth subterminal and oblique, maxillary extending to or slightly beyond the vertical of anterior margin of orbit. Mouth lacking obvious anterior notch and jaws relatively straight. Eyes rather large, upper lateral. Interorbital width approximately equal to or slightly less than snout length. Distinct nuptial tubercles on head and anal fin rays of adult male, one row of 3–6 on each side of lower jaw, one row of three or four on cheek. One row of 4–6 large, rounded tubercles on snout, usually united basally to form a plate. Body with moderately cycloid scales. Lateral line complete, depressed downward above pectoral fin and extending along lower half of body to mid-lateral on caudal peduncle. Tiny scales on belly.

Pectoral fin reaching or extending slightly beyond pelvic fin origin when depressed in adult male, but not reaching the origin in female. Pelvic fin origin vertical or slightly behind dorsal fin origin, extending to anal fin origin when depressed in adult male, but not reaching the origin in female. Anal fin rays rather elongate, especially first to fourth branched rays longer in male, with the rear tip extending beyond vertical line of caudal fin base. Caudal fin forked, lower lobe almost equal to upper one.

Coloration. In life, body brightly colored, males more colorful than females. Ten to thirteen irregular blue-green cross-bars separated by pale cross-bars on the flanks. In adult male, uniform narrow pale pink cross-bars on trunk and two on caudal peduncle widening significantly; upper and lateral sides of head grayish and transitioning to orange-red on ventral side and lower margin of cheek. Dorsal fin rays transparent and membrane black-grey with orange margin. Anal fin and caudal fin rays transparent, membrane pale yellow or colorless. Pectoral fins orange and pelvic fins yellow (Fig. 3A). In females, narrow bright yellow bars on trunk and always absent on caudal peduncle. Dorsal fin black-grey. Pectoral fin orange yellow. Pelvic fin, anal fin and caudal fin transparent and colorless (Fig. 3B). In 10% formalin-fixed specimens, dorsal and flank of head and body grayish brown; ventral surface of head and abdomen white to yellowish. Dorsal and caudal fin dark gray. Pectoral, pelvic and caudal fin grayish white (Fig. 2).

Distribution

The new species is only found in Qiantang and Oujiang River systems in Zhejiang Province and the tributaries of the lower Yangtze River adjacent to the Qiantang River.

Habitat

The new species lives in the headwaters of streams with moderate flow velocities and clear water with small to medium-sized pebbles and boulders in the substrate (Fig. 4).

Figure 4. 

Image of the habitat of Opsariichthys iridescens sp. nov., near riverbed with stones.

Etymology

Iridescens is the Latin form of the word iridescent. Here, it refers to the unique body color, which is brighter than that of any known species in the genus. In this study, we propose the Chinese common name Hóng Cǎi Mǎ Kǒu Yú (虹彩马口鱼).

Morphological analysis

PCA was performed on three Opsariichthys species based on the morphological data. Fig. 5 shows the principal component score plot. The cumulative contribution of PC1 and PC2 was 79.28%, which represents most of the information in the original data. The contribution rate of PC1 was 58.63%, and the eigenvalue was 23.34, which was the highest contribution to the model. The contribution rate of PC2 was 20.65%, and the eigenvalue was 4.09. In the principal component score plot, O. evolans was mainly clustered on the negative side of the origin of the PC1 axis, whereas the new species and O. bidens were mainly distributed on the origin of the PC1 axis and on the positive side, so that the three species could be clearly distinguished from each other.

Figure 5. 

PCA score plots for PC1 and PC2.

Through typical discriminant analysis, a table of coefficients of typical discriminant functions related to the morphological data was obtained, and two typical discriminant functions were established. The eigenvalues of the two typical discriminant functions were 23.343 and 4.085, and their variance contribution rates were 85.1% and 14.9%, respectively. According to the two discriminant functions, the scores of different Opsariichthys species were calculated, and scatter plots of the scores of different Opsariichthys species were obtained by using these two discriminant functions as horizontal and vertical coordinates, respectively (Fig. 6). As shown in the scatter plot, none of the three species overlapped, suggesting that they are different species.

Figure 6. 

Canonical discriminant score plot for the three species of Opsariichthys.

Molecular phylogenetic analysis

In this study, a total of 72 Cyt b gene sequences from 27 species of the opsariichthine group were used, and two additional Cyt b sequences from Aphyocypris chinensis were used as outgroups. Based on the length heterogeneity of the sequences from GenBank, four sequences were compared to obtain a sequence length of 913 bp for Z. platypus, Opsariichthys sp. A, O. acutipinnis, and O. duchuunguyeni, and the remaining 68 opsariichthine group sequences were 1140 bp in length. The base frequencies (excluding outgroups) were A = 25.6%, C = 28.1%, G = 16.2%, and T = 30.1%. The content of A+T (55.7%) was significantly greater than that of G+C (44.3%), which was basically consistent with the characteristics of the mitochondrial genes of fish that have high A and T contents and low G and C contents. There were 672 conserved sites, accounting for 58.9% of the total number of sites; 468 mutated sites, accounting for 41.1% of the total number of sites; 74 single mutated sites, accounting for 6.5% of the total number of sites; and 394 parsimony informative sites, accounting for 34.6% of the total number of sites. The conversion ratio of the sequence was 3.03.

The phylogenetic tree of the opsariichthine group was reconstructed based on the NJ, BI, and ML analyses, and all three trees had a consistent topology despite the differences in support at some branches. Here, we only show the topology of the NJ tree while adding the self-expanding support of the BI and ML trees at the nodes. The topology of the NJ tree (Fig. 7) shows that Opsariichthys and Zacco form a monophyletic group and are sister groups to each other. The new monophyly species clustered in the Opsariichthys group, was located at the base of the genus, and formed a sister group with other Opsariichthys species with the support of 82/96/0.97 (NJ/ML/BI).

Figure 7. 

Phylogenetic relationships of opsariichthine derived from the NJ tree based on the Cyt b gene sequences; the values at the nodes correspond to the support values for the NJ/ML/BI methods. ‘-’ indicates that the value is less than 50%.

The genetic distances among the species of the opsariichthine group were calculated based on a K2P model. The genetic distances among the new species and the congeneric species and lineages ranged from 0.143 to 0.186, and those among the inter-genus species ranged from 0.144 to 0.193. Among them, the smallest genetic distance from the new species was observed for Opsariichthys sp. D, with a value of 0.143, while the greatest genetic distance from the new species was observed for Parazacco spilurus, with a value of 0.193 (Table 5).

Table 5.
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Nucleotide distances between the opsariichthine group species based on the K2P model.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27
O. iridescens sp. nov.
O. bidens 0.146
O. evolans 0.144 0.138
O. acutipinnis 0.146 0.126 0.055
O. chengtui 0.150 0.158 0.098 0.110
O. duchuunguyeni 0.186 0.155 0.128 0.128 0.117
O. hainanensis 0.152 0.144 0.089 0.109 0.106 0.141
O. kaopingensis 0.149 0.133 0.092 0.095 0.099 0.144 0.101
O. macrolepis 0.147 0.135 0.072 0.074 0.093 0.119 0.099 0.087
O. minutus 0.162 0.154 0.099 0.114 0.109 0.143 0.082 0.105 0.107
O. pachycephalus 0.144 0.148 0.099 0.115 0.101 0.144 0.106 0.051 0.101 0.094
O. uncirostris 0.170 0.074 0.156 0.144 0.163 0.184 0.152 0.145 0.148 0.159 0.155
Opsariichthys sp. A 0.155 0.136 0.046 0.060 0.117 0.131 0.100 0.089 0.079 0.110 0.106 0.159
Opsariichthys sp. B 0.147 0.142 0.062 0.061 0.088 0.120 0.097 0.100 0.069 0.100 0.098 0.158 0.068
Opsariichthys sp. C 0.150 0.147 0.077 0.087 0.095 0.121 0.104 0.095 0.059 0.096 0.097 0.159 0.091 0.074
Opsariichthys sp. D 0.143 0.147 0.076 0.091 0.100 0.115 0.097 0.096 0.053 0.103 0.105 0.165 0.092 0.072 0.052
Opsariichthys sp. E 0.153 0.138 0.077 0.088 0.095 0.117 0.102 0.102 0.041 0.104 0.105 0.152 0.094 0.071 0.065 0.070
Z. acanthogenys 0.147 0.164 0.164 0.171 0.164 0.188 0.167 0.160 0.157 0.183 0.162 0.178 0.173 0.166 0.162 0.164 0.170
Z. platypus 0.146 0.154 0.157 0.150 0.156 0.173 0.172 0.155 0.155 0.176 0.166 0.167 0.162 0.165 0.164 0.170 0.172 0.085
Z. sinensis 0.149 0.154 0.156 0.148 0.154 0.173 0.160 0.158 0.143 0.172 0.160 0.169 0.164 0.163 0.167 0.167 0.164 0.076 0.043
Z. tiaoxiensis 0.144 0.164 0.165 0.165 0.163 0.184 0.171 0.152 0.153 0.187 0.162 0.177 0.164 0.170 0.162 0.170 0.168 0.046 0.081 0.080
P. fasciatus 0.192 0.209 0.194 0.202 0.194 0.240 0.183 0.189 0.202 0.216 0.206 0.216 0.195 0.193 0.214 0.195 0.200 0.206 0.198 0.205 0.197
P. spilurus 0.193 0.202 0.204 0.212 0.209 0.254 0.189 0.214 0.198 0.214 0.211 0.221 0.203 0.190 0.212 0.200 0.207 0.196 0.198 0.196 0.195 0.107
N. sieboldii 0.182 0.184 0.192 0.194 0.187 0.221 0.174 0.181 0.188 0.205 0.188 0.192 0.184 0.190 0.192 0.186 0.190 0.168 0.171 0.187 0.172 0.165 0.163
N. temminckii 0.171 0.180 0.186 0.185 0.185 0.207 0.184 0.181 0.191 0.200 0.194 0.190 0.179 0.191 0.192 0.181 0.197 0.161 0.163 0.169 0.161 0.176 0.165 0.126
C. barbatus 0.172 0.196 0.182 0.186 0.181 0.213 0.185 0.194 0.188 0.195 0.198 0.213 0.185 0.166 0.182 0.173 0.193 0.166 0.164 0.171 0.169 0.168 0.163 0.141 0.130
C. pingtungensis 0.187 0.207 0.198 0.204 0.209 0.229 0.209 0.202 0.196 0.218 0.209 0.210 0.200 0.196 0.199 0.183 0.200 0.180 0.172 0.190 0.180 0.178 0.183 0.159 0.154 0.097

Diagnostic key to Opsariichthys species

1 Absence of distinct anterior notches on the upper lip; lateral jaws relatively straight 2
– Presence of a distinct anterior notch on the upper lip; lateral jaws undulated 9
2 2 rows of pharyngeal teeth 3
− 3 rows of pharyngeal teeth 5
3 Fewer than 60 lateral-line scales 4
− More than 60 lateral-line scales O. chengtui (the upper Yangtze River)
4 2 or 3 rows with 15–21 rather small, rounded tubercles in total that are well separated on the lower jaw in males; body with 11–13 greenish blue stripes of almost equal width in males O. macrolepis (the upper Yangtze River)
− Single row of 3–6 rather large, rounded tubercles on the lower jaw of males, united basally to form a plate; 10–13 pale pink strips on the body of males, uniform and narrow on the trunk and widening significantly on the caudal peduncle O. iridescens sp. nov. (southeast China)
5 Fewer than 42 lateral–line scales; 13 or 14 predorsal scales; 3 scales below the lateral line; very narrow body width; 2 rows with 12–15 rather large and rounded tubercles on the lower jaw in adult males O. duchuunguyeni (northern Vietnam)
− More than 42 lateral-line scales; 15–17 predorsal scales; 4 scales below the lateral line modally; a rather narrow to thick body width; a series of 4–7 rounded tubercles on lower jaw in adult males 6
6 42–45 lateral-line scales; 15–17 predorsal scales; a rather narrow body width; maxillary that does not extend to or slightly reaches the vertical anterior margin of the orbit; pectoral fin reaching or extending far beyond the origin of the ventral fin 7
− More than 45 lateral-line scales; 18–23 predorsal scales; rather thick body width; maxillary that extends to or far beyond the vertical anterior margin of the orbit; pectoral fin that does not extend beyond the origin of the ventral fin 8
7 18–20 circum-peduncular scales; 15 pectoral fin rays modally; maxillary that extends to the vertical anterior margin of the orbit; a pectoral fin that does not extend to the origin of the ventral fin; 9 scales above the lateral line modally O. acutipinnis (southern China)
− 16 or 17 circum-peduncular scales; 14 pectoral fin rays modally; maxillary that does not extend to the vertical anterior margin of the orbit; pectoral fin that extends far beyond the origin of the ventral fin; 8 scales above the lateral line modally O. evolans (northern Taiwan Island, eastern mainland China)
8 More than 48 lateral-line scales (mode 50–54); 20–23 predorsal scales; 40 or 41 vertebrae; maxillary that extends to or beyond the vertical midline of the orbit in females; opercle and ventral side of head orange-red to pink-red in adult males O. pachycephalus (northern, middle and western Taiwan Island)
− 40–45 lateral-line scales (mode 45–47); 18 or 19 predorsal scales; 39 vertebrae; maxillary that extends to or slightly beyond the vertical anterior margin of orbit in females; opercle and ventral side of head bright yellow in adult males O. kaopingensis (southern Taiwan Island)
9 Fewer than 50 lateral-line scales; 8–10 scales above the lateral line 10
− More than 50 lateral-line scales; 10–12 scales above the lateral line O. uncirostris (Japan and Korea)
10 45–50 lateral-line scales; rounded tubercles on lower jaw rather small and arranged in 3 rows in males 11
− 40–43 lateral-line scales; rounded tubercles on lower jaw rather large and arranged in 2 or 3 rows in males 13
11 45–47 lateral-line scales; 8 or 9 scales above lateral line; 17–19 circum-peduncular scales; 40–42 vertebrae 12
− 46–50 lateral-line scales; 9 or 10 scales above lateral line; 19 or 20 circum-peduncular scales; 38 or 39 vertebrae O. amurensis (Amur River)
12 19–21 predorsal scales; 9 scales above lateral line; 41 or 42 vertebrae O. bidens (northern and east China)
− 16–18 predorsal scales; 8 scales above lateral line modally; 40 or 41 vertebrae O. minutus (southern China)
13 41–43 lateral-line scales (mode 42); 15 or 16 predorsal scales modally; rounded tubercles large or small arranged in 2 or 3 rows; rather small head; body strongly laterally compressed at position of anal fin origin 14
− 40 or 41 lateral-line scales (mode 41); 17 predorsal scales modally; rounded tubercles on lower jaw rather large and arranged in 2 rows; rather large head; body rather wide at anal fin origin O. hainanensis (Hainan Island)
14 13–15 pectoral fin rays (mode 14); 16–19 caudal peduncle scales (mode 17); 15–18 predorsal scales (mode 16); 14–16 anterior scales before pelvic origin (mode 15); rounded tubercles on lower jaw rather large and arranged in 3 rows in males; body with 14 greenish blue cross-bars in males; maxillary that extends to vertical midline of orbit in females; snout length of approximately 32–33% in males; interorbital width of approximately 30% in males O. dienbienensis (northern Vietnam)
− 13 or 14 pectoral fin rays (mode 13); 18 caudal peduncle scales modally; 15–18 predorsal scales (mode 15); 13–15 anterior scales before the pelvic origin (mode 14); rounded tubercles on lower jaw rather small and arranged in 2 or 3 rows in males; body with 13 greenish blue cross-bars in males; maxillary does not extend to vertical midline of orbit in females; snout length of approximately 30% in males; interorbital width of approximately 27–28% in males O. songmaensis (Ma River of Vietnam)

Discussion

For a long time, the genus Opsariichthys was thought to include only one species, O. bidens, which was widely distributed in East Asia (Chen 1982; Chen and Chu 1998). With the help of modern molecular techniques, the nuptial tubercles on the cheeks of males and the lateral cross-bars on the body, which were first identified by Chen et al. (2009) and later confirmed by Huang et al. (2017), were found to be the key diagnostic features distinguishing this genus from its sister genus Zacco. Thus, the taxonomy of the two genera gradually became clearer. Therefore, based on the stripe features and phylogeny of this study, we ascribe O. iridescens sp. nov. to the genus Opsariichthys. In addition, based on geographic distribution, the results of morphological and PCA analyses also indicated the validity of the new species. With many independent rivers and diverse habitats, southeast mainland China is rich in freshwater fish species, and some species have a common distribution with northern Taiwan, including O. evolans, which was used for the comparison in this study. According to our investigations, in addition to the new species, only O. bidens and O. evolans are found in Zhejiang Province, north of the Wuyi Mountains, and are distinct from the other congeners. Based on our observations, all Opsariichthys species can be divided into two types: one with a large mouth, a conspicuous anterior notch on the upper lip, and undulated jaws; and another with a small mouth, no distinct anterior notch on the upper lip, and relatively straight jaws. These two types are morphological adaptations to feeding habits, carnivores and omnivores, respectively. The new species belongs to the latter; however, the phylogenetic analysis in this study shows that the two types do not form monophyletic groups, indicating that mouth shape may be a derived evolutionary trait. In addition to the difference in scale numbers (Table 3), the new species also has several obvious morphological features that distinguish it from other species in the same group: 1) the nuptial tubercles on the cheeks and lower jaw of the adult males were united basally to form a plate, similar to the species of Zacco; 2) two rows of pharyngeal teeth; and 3) the narrow, pale, lateral cross-bars that are almost uniform in width on the trunk and widening significantly on the caudal peduncle (Table 4). In the diagnostic key for Opsariichthys species presented above the data for all but three species was obtained from published sources (Yang and Huang 1964; Chen et al. 2009; Huynh and Chen 2013; Wang et al. 2019).

Wang et al. (2019) used a 3% Cyt b gene genetic distance to delimit the opsariichthine fish species, identified 20 haplogroups of Opsariichthys, and reported that the species diversity of this genus was underestimated. The new species reported herein does not belong to any of the haplogroups in Wang et al. (2019), and its genetic distance from both congeneric and intergeneric species exceeds 14%, which is much greater than their 3% limit (see Table 5). Our phylogenetic results are consistent with the results of previous studies (Huang et al. 2017; Wang et al. 2019; Zhang et al. 2023) (Fig. 7). Opsariichthys and Zacco, which both have lateral cross-bars, are both monophyletic and form separate clades, which supports the use of stripes as key diagnostic features for distinguishing them. Moreover, O. iridescens sp. nov., as a monophyletic group, is located at the base of all Opsariichthys species. In conclusion, the genetic distance and phylogenetic analyses support morphological distinctiveness and the validity of the new species.

Comparative materials

O. evolans: SHOU2021060004-006, 3 specimens, 67.5–112.0 mm SL, She County, Qiantang River System, Anhui Province, China; SHOU2021060091, 1 specimen, 103.3 mm SL, Suichang County, Qiantang River System, Zhejiang Province, China; SHOU2021060145, 1 specimen, 83.5 mm SL, Qingyuan County, Ou River System, Zhejiang Province, China; SHOU202208005-006, 2 specimens, 71.4–77.5 mm SL, Shangyu District, Cao’e River System, Zhejiang Province, China; SHOU202208031-040, 10 specimens, 71.2–84.0 mm SL, Shengzhou City, Cao’e River System, Zhejiang Province, China.

O. bidens: SHOU202209008-012, 5 specimens, 76.1–100.6 mm SL, Qingyuan County, Ou River System, Zhejiang Province, China; SHOU202111001-005, 5 specimens, 99.6–131.6 mm SL, Shengzhou City, Cao’e River System, Zhejiang Province, China.

Acknowledgments

We are grateful to the reviewers for dedicating their time and expertise to enhance our work; to Zhuo-cheng Zhou, Wei Sun, Yun-feng Huang, Zhi Chen, Hui Cao, and Xiang Han for assistance in the field survey.

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 funded by a grant from the National Natural Science Foundation of China (No. 31872207).

Author contributions

Conceptualization: HDG. Data curation: XP. Funding acquisition: JQY. Investigation: JJZ. Resources: JJZ. Visualization: HDG. Writing – original draft: XP. Writing – review and editing: JQY.

Author ORCIDs

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

Hong-Di Gao https://orcid.org/0009-0004-6891-3209

Jin-Quan Yang https://orcid.org/0000-0003-0387-1824

Data availability

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

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1Xin Peng and Jia-Jun Zhou contributed equally to this work.
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