Research Article |
Jia-Yue Ge‡, Zheng-Quan Nong§, Jian Yang|, Li-Na Du‡, Jia-Jun Zhou¶#
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Corresponding author: Li-Na Du ( dulina@mailbox.gxnu.edu.cn ) Corresponding author: Jia-Jun Zhou ( cnwaters@foxmail.com ) Academic editor: Nicolas Hubert
© 2024 Jia-Yue Ge, Zheng-Quan Nong, Jian Yang, Li-Na Du, Jia-Jun 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:
Ge J-Y, Nong Z-Q, Yang J, Du L-N, Zhou J-J (2024) Taxonomic revision of the cavefish genus Karstsinnectes (Cypriniformes, Nemacheilidae), with a description of a new species from Guangxi Province, China. Zoosystematics and Evolution 100(2): 663-673. https://doi.org/10.3897/zse.100.118061
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Abstract
The blind cavefish genus Karstsinnectes, established in 2023, is the subject of taxonomic revision in the present study. Five valid species are recognized, including one new species, Karstsinnectes longzhouensis sp. nov., described from Guangxi, China, based on a combination of morphological evidence. Karstsinnectes longzhouensis sp. nov. can be distinguished from all other congeners based on the presence of a lateral line, 11–12 branched pectoral fin rays, and five branched pelvic fin rays. Additionally, due to the loss of the type specimens, a neotype is designated for K. parvus. The lateral line of K. hyalinus is revised as lacking in this study. A key to all valid Karstsinnectes species is provided. Blind cavefish serve as a valuable natural framework for investigating convergent and adaptive evolutionary processes. The survival of cavefish is under significant threat due to human activities, climate change, water pollution, and invasive species. Thus, to preserve these valuable species, it is crucial to implement various conservation measures, such as habitat protection, artificial breeding, and fundamental research.
Key Words
Blind cavefish, complete mitochondrial genome, morphology, Taxonomy, Xijiang River
Introduction
Karst caves and subterranean streams represent dominant geomorphological features in the Guangxi, Guizhou, Sichuan, and Yunnan provinces and Chongqing City of China. These regions are renowned for harboring many unique cave-dwelling fish species (
In December 2022, four Karstsinnectes specimens were collected from a cave in Longzhou County, Chongzuo City, Guangxi, China. Morphological characters and molecular analyses indicated that these specimens represented an undescribed species of Karstsinnectes. Additionally, a taxonomic revision of K. acridorsalis and K. hyalinus is provided, and a neotype is designated for K. parvus herein.
Materials and methods
All care and use of experimental animals complied with the relevant laws of the Chinese Laboratory of Animal Welfare and Ethics (GB/T 35892-2018). Specimens of Karstsinnectes longzhouensis sp. nov. were rapidly euthanized by an overdose of anesthetic clove oil. The right-side pectoral fin and pelvic fin were excised and preserved in 99% ethanol. Specimens for morphological study were initially stored in 10% formalin, then transferred to 75% alcohol for long-term preservation at the Kunming Natural History Museum of Zoology, Kunming Institute of Zoology (
Counts and measurements followed
Complete mitochondrial genome sequencing data were submitted to GenBank under Accession No. OR947935. The mitogenome of OR947935 was sequenced on Illumina Novaseq 6000 (Origingene Bio-pharm Technology Co. Ltd., Shanghai, China). The quality of sequencing raw data was evaluated by Fastqc (v.0.11.8) and trimmed using Cutatapt (v.4.8) software (Martin 2011). Obtained Illumina reads were de novo assembled using the NOVOPlasty software (
Results
Karstsinnectes
Karstsinnectes Zhou, Luo, Wang, Zhou & Xiao, 2023, 696 original descriptions.
Type species
Oreonectes anophthalmus Zheng, 1981.
Diagnosis
Base of anterior nostril tube-like and tip not elongated to barbel-like; anterior and posterior nostrils adjacent; lips with furrows; caudal peduncle with adipose crests; bony capsule of swim bladder opens posteriorly.
Remarks
In the family Nemacheilidae, the genera Eonemachilus Berg, 1938; Karstsinnectes; Micronemacheilus Rendahl, 1944; Protonemacheilus Yang & Chu, 1990; Traccatichthys Freyhof & Serov, 2001; and Yunnanilus Nichols, 1925, are characterized by a tube-like anterior nostril with tip not elongated to barbel-like structure (
Species included
Karstsinnectes acridorsalis (Lan, 2013), K. anophthalmus (Zheng, 1981), K. hyalinus (Lan, Yang & Chen, 1996), K. longzhouensis sp. nov., and K. parvus (Zhu & Zhu, 2014).
Key to species of Karstsinnectes
| 1 | Caudal fin truncated | K. anophthalmus |
| – | Caudal fin forked | 2 |
| 2 | Body covered by scales | K. hyalinus |
| – | Body scaleless | 3 |
| 3 | Lateral line present | 4 |
| – | Lateral line absent | K. acridorsalis |
| 4 | Pectoral fin with 10 branched rays, five branched pelvic fin rays | K. parvus |
| – | Pectoral fin with 11 or 12 branched rays, six branched pelvic fin rays | Karstsinnectes longzhouensis sp. nov. |
Karstsinnectes acridorsalis
Oreonectes acridorsalis Lan, 2013: 68, fig. 50 (Bamu Town, Tian’e County, Hechi City, Guangxi).
Troglonectes acridorsalis Xiao & Lan, 2023: 33 (Bamu Town, Tian’e County, Hechi City, Guangxi).
Karstsinnectes acridorsalis
Material examined
Paratypes. 2 ex. China; Guangxi, Hechi City, Tian’e County, Bamu Town, 22.8754°N, 107.1947°E, 284 m a.s.l. CLJH 1202001, CLJH 04100607, 37.9–38.1 mm SL, deposited in the Fishery and Animal Husbandry Bureau of Du’an, Guangxi, China.
Diagnosis
Karstsinnectes acridorsalis differs from K. anophthalmus by caudal fin forked (vs. truncated), 14 branched caudal-fin rays (vs. 12), longer and lower head (length 29.9%–32.7% of SL vs. 22.7%–24.6%, height 34.6%–39.6% of head length vs. 41.0%–44.0%), longer pectoral fin (61.6%–67.7% of distance between pectoral-fin origin and pelvic-fin origin vs. 35.9%–48.9%); from K. hyalinus by scaleless (vs. scaled), five branched anal-fin rays (vs. four), 14 branched caudal-fin rays (vs. 11 or 12); from K. parvus and K. longzhouensis sp. nov. by lateral line absent (vs. present), lower body (body depth 13.9%–15.5% of SL vs. 17.1%–18.4% and 16.1%–19.4%, respectively), shorter caudal peduncle (length 15.7%–15.9% of SL vs. 18.4%–22.3% and 17.3%–19.5%, respectively).
Description
Body elongated, head depressed, snout depressed, forehead raised, head height at nostril 46.1%–67.9% of maximum head height. Body trunk compressed, with maximum body depth anterior to dorsal-fin origin, deepest body depth 13.9%–15.5% of SL. Dorsal profile of head and predorsal profile slightly convex, clearly concave from dorsal-fin origin to tip of dorsal fin, and gradually convex from tip of dorsal fin to anterior quarter of caudal fin due to caudal adipose keel on upper edge of caudal peduncle. Ventral profile of head straight, nearly straight from pectoral-fin insertion to anal-fin origin, convex from posterior margin of anal-fin base to anterior quarter of caudal fin due to caudal adipose keel on lower edge of caudal peduncle.
Morphometric and meristic data of the genus Karstsinnectes. Range, mean, and standard deviation (mean ± standard deviation (SD)).
| K. acridorsalis (N = 2) | K. anophthalmus (N = 4) | K. hyalinus (N = 3) | Karstsinnectes longzhouensis sp. nov. (N = 4) | K. parvus (N = 3) | |
|---|---|---|---|---|---|
| Total length (mm) | 44.8–45.9 (45.3 ± 0.8) | 30.5–42.8 (36.4 ± 5.1) | 47.4–47.5 (47.4 ± 0.1) | 57.8–73.3 (64.6 ± 6.8) | 32.3–34.8 (33.4 ± 1.3) |
| Standard length (mm) | 37.9–38.1 (38.0 ± 0.1) | 25.3–36.9 (31.4 ± 4.8) | 38.9–40.2 (39.5 ± 1.0) | 49.4–60.1 (53.6 ± 4.8) | 26.5–28.3 (27.1 ± 1.1) |
| Percentage of standard length (%) | |||||
| Deepest body depth | 13.9–15.5 (14.7 ± 1.1) | 11.0–14.4 (13.2 ± 1.6) | 19.9–23.6 (21.6 ± 1.8) | 16.1–16.4 (17.8 ± 1.4) | 17.1–18.4 (17.9 ± 0.7) |
| Lateral head length | 29.9–32.7 (31.3 ± 2.0) | 22.7–24.6 (23.5 ± 0.8) | 27.1–29.2 (28.0 ± 1.1) | 30.2–34.0 (32.2 ± 1.6) | 32.5–33.0 (32.7 ± 0.2) |
| Prodorsal length | 54.4–55.5 (54.9 ± 0.8) | 59.5–62.6 (60.5 ± 1.4) | 55.9–59.0 (57.7 ± 1.6) | 55.1–57.3 (56.2 ± 1.1) | 52.9–56.3 (54.8 ± 1.8) |
| Prepelvic length | 52.9–54.6 (53.7 ± 1.2) | 57.4–58.3 (57.8 ± 0.5) | 52.2–56.8 (55.1 ± 2.6) | 55.6–58.3 (57.4 ± 1.3) | 53.5–58.1 (56.0 ± 2.3) |
| Preanal length | 74.2–75.1 (74.7 ± 0.6) | 68.0–76.3 (73.7 ± 3.9) | 74.4–79.8 (77.8 ± 2.9) | 74.7–76.0 (75.4 ± 0.6) | 71.8–76.1 (74.6 ± 2.4) |
| Preanus length | 67.5–70.8 (69.1 ± 2.3) | - | 70.6–74.0 (72.5 ± 1.7) | 69.4–71.8 (70.2 ± 1.1) | 61.7–74.1 (69.2 ± 6.6) |
| Caudal peduncle length | 15.7–15.9 (15.8 ± 0.1) | 13.2–17.0 (15.4 ± 1.7) | 15.1–16.2 (15.7 ± 0.5) | 17.3–19.5 (18.1 ± 1.0) | 18.4–22.3 (19.9 ± 2.1) |
| Caudal peduncle depth (containing caudal adipose keels) | 7.3–8.3 (7.8 ± 0.7) | 5.7–8.7 (6.9 ± 1.3) | 13.0–14.7 (13.8 ± 0.9) | 9.2–11.7 (10.5 ± 1.1) | 8.4–9.8 (9.2 ± 0.7) |
| Head width | 11.7–12.3 (12.0 ± 0.4) | 14.1–16.8 (15.3 ± 1.2) | 16.1–17.6 (16.7 ± 0.8) | 17.7–21.5 (19.4 ± 1.6) | 14.9–18.0 (16.8 ± 1.7) |
| Percentage of lateral head length (%) | |||||
| Head depth | 34.6–39.6 (37.1 ± 3.5) | 41.0–44.0 (42.6 ± 1.3) | 45.1–48.5 (46.9 ± 1.7) | 42.3–49.1 (45.4 ± 3.0) | 40.8–44.6 (42.7 ± 1.9) |
| Head width | 37.5–39.2 (38.4 ± 1.2) | 60.0–73.4 (65.5 ± 6.0) | 59.5–60.3 (59.8 ± 0.4) | 52.1–71.1 (60.4 ± 8.2) | 45.8–54.5 (51.3 ± 4.8) |
| Percentage of caudal-peduncle length (%) | |||||
| Caudal peduncle depth (containing caudal adipose keels) | 46.1–51.9 (49.0 ± 4.1) | 33.6–57.2 (45.4 ± 9.9) | 81.3–97.4 (87.8 ± 8.5) | 47.0–66.1 (58.5 ± 8.1) | 37.7–53.1 (46.8 ± 8.1) |
| Percentage of distance from pectoral-fin origin to pelvic-fin origin | |||||
| Pectoral-fin length | 61.6–67.7 (64.6 ± 4.3) | 35.9–48.9 (40.5 ± 6.1) | 66.1–74.8 (70.8 ± 4.4) | 72.4–85.9 (77.9 ± 5.8) | 67.5–76.8 (73.3 ± 5.0) |
| Dorsal-fin rays | 3, 8–9 | 3, 7 | 3, 7 | 3, 9 | 3, 9 |
| Pectoral-fin rays | 1, 10 | 1, 10 | 1, 11 | 1, 11–12 | 1, 10 |
| Pelvic-fin rays | 1, 5 | 1, 4 | 1, 5 | 1, 5 | 1, 6 |
| Anal-fin rays | 3, 5 | 3, 5 | 3, 4 | 3, 5 | 3, 5 |
| Caudal-fin branched rays | 14 | 12 | 11–12 | 13–14 | 12–13 |
Anterior and posterior nostrils adjacent, distance less than posterior nostril diameter, base of anterior nostril tube-shaped and tip not elongated to barbel-like. Eyes absent. Mouth inferior, snout rounded, upper and lower lips smooth, lower lip with V-shaped median notch. Three pairs of barbels, inner and outer rostral barbels reaching mouth corner, and maxillary barbel reaching anterior margin of interopercle. Inner gill rakers on first gill arch nine (one specimen).
Dorsal fin with three unbranched and eight branched rays, distal margin straight, origin posterior to pelvic-fin origin, predorsal length 54.3%–55.5% of SL. Pectoral fin with one unbranched and 10 branched rays, pectoral-fin length 61.6%–67.7% of distance between pectoral-fin origin and pelvic-fin origin. Pelvic fin with one unbranched and five branched rays, tip of pelvic fin not reaching anus. Anal fin with two unbranched and five branched rays, distal margin straight. Anus abutting anal-fin base. Caudal fin forked. High caudal adipose keels on upper and lower edges of caudal peduncle, height at most of upper adipose keel nearly 1/2 caudal peduncle depth. Caudal peduncle depth 46.1%–51.9% of its length (containing adipose keels). Lateral line and cephalic sensory pores absent. Body scaleless.
Coloration
Whole body translucent, without color pattern. Fin membrane hyaline.
Distribution and habitat
Only known from the type locality. Karstsinnectes acridorsalis inhabits a subterranean river, 22.8754°N, 107.1947°E, 284 m a.s.l. Co-inhabitants of the stream include Triplophysa tianeensis Chen, Cui & Yang, 2004, Sinocyclocheilus furcodorsalis Chen, Yang & Lan, 1997, and Hongshuia megalophthalmus (Chen, Yang & Cui, 2006).
Remarks
The population of K. acridorsalis is small. Initially described by
Karstsinnectes hyalinus
Heminoemacheilus hyalinus Lan, Yang & Chen, 1996, 109–112 (Bao’an Township, Du’an County, Hechi City, Guangxi).
Karstsinnectes hyalinus
Material examined
3 ex. China; Guangxi, Hechi City, Du’an County, Bao’an Township, 24.0709°N, 107.9027°E, 283 m a.s.l. GXNU 94098009–94098011, 38.9–40.2 mm SL.
Diagnosis
Karstsinnectes hyalinus can be distinguished from other members of Karstsinnectes based on body-scaled (vs. scaleless). It can be further differentiated from K. anophthalmus by caudal fin forked (vs. truncated); from K. acridorsalis, Karstsinnectes longzhouensis sp. nov., and K. parvus by seven branched dorsal-fin rays (vs. eight in K. acridorsalis and nine in Karstsinnectes longzhouensis sp. nov. and K. parvus).
Description
Body elongated, head depressed. Body trunk compressed, dorsal profile of head and predorsal profile gradually convex, with maximum body depth in middle of pectoral-fin origin and pelvic-fin origin. After dorsal-fin base, dorsal profile of caudal peduncle convex due to developed caudal adipose keel on upper edge of caudal peduncle. Ventral profile of head straight, slightly convex from pectoral-fin origin to pelvic-fin origin, straight from pelvic-fin origin to caudal-fin base.
Anterior and posterior nostrils adjacent, distance less than posterior nostril diameter, base of anterior nostril tube-shaped and tip not clearly elongated to barbel-like. Eyes absent. Mouth inferior, snout obtuse, upper and lower lips smooth. Three pairs of barbels, inner rostral barbel reaching mouth corner, outer rostral and maxillary barbels reaching anterior margin of interopercle. One specimen with one outer and 12 inner gill rakers on first gill arch.
Dorsal fin with two branched and seven branched rays, distal margin straight, origin slightly anterior to pelvic-fin origin. Pectoral fin with one unbranched and 11 branched rays, pectoral-fin length 66.1%–74.8% of distance between pectoral-fin origin and pelvic-fin origin. Pelvic fin with one unbranched and five branched rays, tip of pelvic fin reaching anus. Anal fin with two unbranched and four branched rays, distal margin straight. Anus abutting anal-fin base. Caudal fin forked, with 11 or 12 branched rays. High caudal adipose keels on upper and lower edges of caudal peduncle, height at most of upper adipose keel nearly 1/2 caudal peduncle depth. Caudal peduncle length 102.7%–123.1% of its depth (containing adipose keels). Lateral line and cephalic sensory pores absent. Body covered by scales, except head and thorax.
Coloration
Whole body translucent, without color pattern. Fin membrane hyaline.
Distribution and habitat
Known only from the type locality, China; Guangxi, Hechi City, Du’an County, Bao’an, 24.0709°N, 107.9027°E, 283 m a.s.l. The cave water in which this species resides serves as the only source of drinking water for nearby residents. The decline in its population is primarily attributed to habitat alterations resulting from the extraction of cave water for domestic purposes (
Remarks
The population of K. hyalinus is extremely small, with its presence currently known only through type specimens collected in 1994, with no additional specimens gathered since. Although the lateral line of K. hyalinus was mentioned in the original description, a re-examination of all type specimens by R. Min, the administrator of the Fish Collection Room, Kunming Natural History Museum of Zoology, Kunming Institute of Zoology, revealed no obvious lateral line pores. Hence, K. hyalinus is described as lacking a lateral line in this study.
Karstsinnectes longzhouensis , sp. nov.
Type materials
Holotype. China (permanent whole specimen in 75% alcohol); Guangxi, Chongzuo City, Longzhou County, Xiadong Town; 22.4222°N, 106.6385°E, 170 m a.s.l.; collected by Z.Q. Nong and J.J. Zhou, 29 December 2022. Kunming Natural History Museum of Zoology,
Paratypes. China (permanent whole specimens in 75% alcohol); same collection data as for holotype, collected by Z.Q. Nong and J.J. Zhou, 29 December 2022;
Diagnosis
Karstsinnectes longzhouensis sp. nov. can be distinguished from all other members of Karstsinnectes based on the combination characteristics of the lateral line present, 11 or 12 branched pectoral-fin rays, and five branched pelvic-fin rays. It can be further distinguished from K. anophthalmus by caudal fin forked (vs. truncated), five branched pelvic-fin rays (vs. four), nine branched dorsal-fin rays (vs. seven), 13 or 14 branched caudal-fin rays (vs. 12); from K. acridorsalis by nine branched dorsal-fin rays (vs. eight), body depth 16.1%–19.4% of SL (vs. 13.9%–15.5%); from K. hyalinus by body scaleless (vs. scaled), lateral line present (vs. absent), nine branched dorsal-fin rays (vs. seven), five branched anal-fin rays (vs. four); from K. parvus by 11 or 12 branched pectoral-fin rays (vs. 10), five branched pelvic-fin rays (vs. six), and uncorrected p distance is 3.9%.
Description
Morphometric data of the type specimens of Karstsinnectes longzhouensis sp. nov. are given in Table
Anterior and posterior nostrils adjacent, distance less than posterior nostril diameter, base of anterior nostril tube-shaped and tip not elongated to barbel-like. Eyes absent. Mouth inferior, snout rounded, upper and lower lips smooth, lower lip with V-shaped median notch. Three pairs of barbels, inner rostral barbel reaching anterior nostril, outer rostral barbel reaching posterior margin of posterior nostril, and maxillary barbel reaching anterior margin of interopercle. Two specimens with 11–12 inner gill rakers on first gill arch.
Dorsal fin with three unbranched and nine branched rays, distal margin of dorsal fin straight, origin anterior to pelvic-fin origin, predorsal length 55.1%–57.3% of SL. Pectoral fin with one unbranched and 10 branched rays, pectoral-fin length 72.4%–85.9% of distance between pectoral-fin origin and pelvic-fin origin. One unbranched and five branched pelvic-fin rays, tip of pelvic fin reaching, but not exceeding anus. Anus abutting anal-fin base. Caudal fin forked, with 13 or 14 branched caudal-fin rays. High caudal adipose keels on upper and lower edges of caudal peduncle, height at most of upper adipose keel less than 1/2 caudal peduncle depth. Caudal peduncle length 151.2%–212.9% of its depth (containing adipose keels). Lateral line and head sensory pores absent. Body scaleless.
Coloration
Dorsal and trunk of body yellowish, abdomen gray and translucent, stomach and intestine visible from outside. Without color pattern. Fin membrane hyaline.
Distribution and habitat
Karstsinnectes longzhouensis sp. nov. inhabits karst caves located in the Guangxi Qinglongshan provincial natural reserve, specifically in Xiadong Town, Longzhou County, Chongzuo City, Guangxi, China (22.4222°N, 106.6385°E, 171 m a.s.l.). The species was observed in a subterranean pool accessed through an oval cave entrance and a narrow passage. The pool water depth exceeded 1 m and was characterized by a substratum of mud and cobblestones.
Etymology
The specific name “longzhouensis” is derived from the Chinese name of the type locality in Longzhou County. Therefore, the Chinese and English common names for this new species are “龙州中华喀鳅” and “Longzhou Chinese Karst Loach,” respectively.
Remarks
On 29 December 2022, Z.Q. Nong collected type specimens within a karst cave. By May 2023, the cave showed significant signs of drying. In another cave located 300 m away, J.J. Zhou collected a deteriorated specimen. Decreased precipitation and the removal of domestic water from the cave appear to have negatively influenced the viability of cavefish during the dry season.
Karstsinnectes parvus
Heminoemacheilus parva Zhu & Zhu, 2014: 18–21 (Ande Town, Napo County, Guangxi).
Karstsinnectes parvus
Neotype designation
Both holotype and paratypes were originally deposited at the Guangxi Fisheries and Animal Husbandry School under registration numbers 2011006–2011009 (
Neotype. China; Guangxi, Baise City, Napo County, Nongma Village, 23.1803°N, 106.0020°E, 934 m a.s.l., collected by J.J. Zhou, J.Q. Luo, X.M. Luo, and Z.X. Qin on 1 May 2023;
Non-type material
2 ex. China; same collected with neotype, collected by J.J. Zhou, J.Q. Luo, X.M. Luo, and Z.X. Qin on 1 May 2023; GXNU 20230501001, GXNU 20230501003, 26.5–28.3 mm SL.
Diagnosis
Karstsinnectes parvus can be distinguished from K. acridorsalis by lateral line present (vs. absent), nine branched dorsal-fin rays (vs. eight), six branched pelvic-fin rays (vs. five), 12 or 13 branched caudal-fin rays (vs. 14); from K. anophthalmus by caudal fin forked (vs. truncated), lateral line present (vs. absent), nine branched dorsal-fin rays (vs. seven), six branched pelvic-fin rays (vs. four); from K. hyalinus by body scaleless (vs. scaled), lateral line present (vs. absent), nine branched dorsal-fin rays (vs. seven), five branched anal-fin rays (vs. four); from Karstsinnectes longzhouensis sp. nov. by 10 branched pectoral-fin rays (vs. 11 or 12), six branched pelvic-fin rays (vs. five).
Description
Body elongated, slightly flattened in front, strongly compressed in back. Maximum body depth anterior to dorsal-fin origin, deepest body depth 17.1%–18.4% of SL. Head depressed and flattened, maximum width greater than maximum depth. Anterior and posterior nostrils adjacent, distance less than posterior nostril diameter, base of anterior nostril tube-shaped and tip not elongated to barbel-like. Eyes absent. Mouth inferior, snout rounded, upper and lower lips smooth, lower lip with V-shaped median notch. Three pairs of barbels, inner rostral barbel reaching anterior nostril, outer rostral barbel reaching posterior margin of posterior nostril, and maxillary barbel reaching anterior margin of interopercle. One specimen with 11 inner gill rakers on first gill arch.
Dorsal fin with three unbranched and nine branched rays, distal margin of dorsal fin straight, origin anterior to pelvic-fin origin, predorsal length 52.9%–56.3% of SL. Pectoral fin with one unbranched and 10 branched rays, pectoral-fin length 67.5%–76.8% of distance between pectoral-fin origin and pelvic-fin origin. Pelvic fin with one unbranched and six branched rays, tip of pelvic fin exceeding anus. Anal fin with three unbranched and five branched rays, distal margin straight. Anus abutting anal-fin base. Caudal fin forked, with 12 or 13 branched rays. High caudal adipose keels on upper and lower edges of caudal peduncle, height at most of upper adipose keel less than 1/2 caudal peduncle depth. Caudal peduncle length 188.4%–265.6% of its depth (containing adipose keels). Lateral line present. Body scaleless.
Coloration
Dorsal and trunk of body gray and translucent, stomach and intestine visible from outside. Without color pattern. Fin membrane hyaline.
Distribution and habitat
Karstsinnectes parvus inhabits a karst cave in Nongma Village, Napo County, Baise City, Guangxi, China; 23.1803°N, 106.0020°E, 934 m a.s.l., in a small and shallow river (approximately 300 m long, depths of less than 20 cm), characterized by substrata composed of mud and cobblestones. Five to six specimens were caught in each survey in 2021.
Remarks
Given the loss of the type specimens three years ago (Y. Zhu, pers. comm.), three specimens of K. parvus were newly collected from the type locality. These specimens conformed to the original description in all aspects except for the caudal fin count. The caudal fin of the holotype was damaged in the original account, preventing verification of the fin ray count from the holotype photograph in the initial description. Lan et al. collected this species from the type locality in 2021 and noted 13 branched rays of the caudal fin (
Genetic comparisons
Based on BI analyses, molecular phylogenies demonstrated that species of Karstsinnectes constituted a monophyletic group with robust support (100% bootstraps). Furthermore, they were sister to the clade comprised of Oreonectes, Micronemacheilus, and Guinemachilus species. Karstsinnectes longzhouensis sp. nov. was determined to be a sister group to K. parvus and further sister to K. anophthalmus and K. acridorsalis (Fig.
Principal component analysis (PCA)
The first two principal components (PCs) explained 71.1% of the variance (Table
Loadings of the first three PCs for the morphometric characters of Karstsinnectes. * loadings > 60%.
| Character | PC1 | PC2 | PC3 |
|---|---|---|---|
| Body depth/SL | 0.871* | 0.271 | -0.126 |
| Head lateral length/SL | 0.798* | -0.445 | 0.221 |
| Prodorsal length/SL | -0.704* | 0.592 | 0.099 |
| Propelvic length/SL | -0.314 | 0.387 | 0.577 |
| Preanal/SL | 0.392 | 0.343 | -0.310 |
| CPL/SL | 0.489 | -0.415 | 0.690* |
| CPD/SL | 0.830* | 0.455 | -0.242 |
| Head width/SL | 0.462 | 0.662* | 0.498 |
| Pectoral-fin length/SL | 0.912* | 0.157 | 0.146 |
| Pelvic-fin length/SL | 0.883* | -0.195 | -0.247 |
| Head depth/head lateral length | 0.404 | 0.779* | 0.248 |
| Head width/head lateral length | -0.206 | 0.896* | 0.257 |
| Pectoral-fin length/distance between pectoral-fin and pelvic-fin origin | 0.912* | -0.193 | 0.083 |
| Pelvic-fin length/distance between pelvic-fin and anal-fin origin | 0.858* | -0.274 | 0.075 |
| CPL/CPD | -0.579 | -0.607* | 0.522 |
| Prp. Tot1 | 46.70% | 24.40% | 11.90% |
Discussion
While
In morphology, K. anophthalmus possesses distinct characteristics from other congeneric species, including an obtuse snout, shorter pectoral and pelvic fins, a pectoral-fin length less than half the distance from its origin to the pelvic-fin origin, and a pelvic fin tip that does not reach the anus. Scatter plots of the first and second PCs of pooled morphometric data of Karstsinnectes also indicated the morphological difference of K. anophthalmus. The morphological difference could indicate that K. anophthalmus represents a new genus. However, the molecular analysis is inconsistent with the morphological evidence. In the phylogenetic tree, K. longzhouensis sp. nov. was determined to be a sister group to K. parvus and further sister to K. anophthalmus and K. acridorsalis. According to
Blind cavefish represent a powerful natural model for studying adaptations in extreme environments. Cave habitats, characterized by limited food resources, low oxygen levels, and perpetual darkness (
The survival of cavefish is significantly threatened by human activities, climate change, water pollution, and invasive species. As of 2021, the Red List of Biodiversity in China includes 13 cavefish species from the Nemacheilidae family (
Conclusions
In this paper, a new blind species is described from Guangxi, China. The phylogenetic tree indicated that the new species belongs to the genus Karstsinnectes. Additionally, the genus diagnosis is redefined, a neotype for K. parvus is designated due to the type specimens lost, and the morphology character of K. hyalinus is revised. The population of these species is quite small and sensitive to human activity. The protection of cave fish is often neglected due to the difficulty of cave exploration. The findings of this study improve our understanding of the species diversity of the genus Karstsinnectes and provide the basis for cavefish protection.
Competing interests
The authors declare that they have no competing interests.
Authors’ contributions
J.Y.G. and L.N.D. measured the specimens, analyzed the data, and prepared the manuscript. L.N.D. and J.Y. conceived and designed the study, analyzed the molecular data, constructed the phylogenetic tree, and provided funding for complete mitochondrial genomes and field surveys. Z.Q.N. and J.J.Z. conducted the field survey. All authors read and approved the final version of the manuscript.
Acknowledgments
This study was funded by the Guangxi Natural Science Foundation Project (2022GXNSFAA035563), Key Laboratory of Ecology of Rare and Endangered Species and Environmental Protection (Guangxi Normal University), Ministry of Education, China (ERESEP2022Z05), Survey and Assessment of Priority Areas for Terrestrial Biodiversity Conservation in Guangxi (2022–2023), and Guangxi Zhuang Autonomous Region Project of Undergraduate on Innovation and Entrepreneurship (S202310602180). We are grateful to J.H. Lan for providing photographs of K. acridorsalis, R. Min for providing photographs of K. anophthalmus and K. hyalinus, and M. Liang for taking photographs of K. parvus. We thank H. Zhou, B.M. Wang, X.M. Luo, J.Q. Luo, and Z.X. Qin for collecting specimens of Karstsinnectes.
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