Karstsinnectes parvus ( Zhu & Zhu, 2014 )

Ge, Jia-Yue, Nong, Zheng-Quan, Yang, Jian, Du, Li-Na & Zhou, Jia-Jun, 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), pp. 663-673 : 663-673

Karstsinnectes parvus ( Zhu & Zhu, 2014)

Figs 1 A, C , 5 ; Table 1

Heminoemacheilus parva Zhu & Zhu, 2014: 18–21 (Ande Town, Napo County, Guangxi).

Karstsinnectes parvus Luo et al., 2023 , 696 (Ande Town, Napo County, Guangxi).

Neotype designation.

Both holotype and paratypes were originally deposited at the Guangxi Fisheries and Animal Husbandry School under registration numbers 2011006–2011009 ( Zhu and Zhu 2014) but were broken and lost three years ago (Y. Zhu, pers. comm.). Conforming with Article 75.3 of the Code ( ICZN 1999 ), a neotype from the type locality is herein designated (Fig. 5 ).

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; KIZ 2023000005 (Fig. 5 ), 26.5 mm SL.

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 ( Xiao and Lan 2023). This observation suggests that the unbranched rays of the caudal fin may have been included in the count of branched rays in the original description.

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. 6 ). Additionally, pairwise comparisons of complete mitochondrial genomes revealed that the average uncorrected p distance between species of Karstsinnectes ranged from 3.96 % to 11.38 % (average 9.65 %). The minimum uncorrected p distance is between K. longzhouensis sp. nov. and K. parvus (3.96 %), and the maximum uncorrected p distance is both between K. acridorsalis and K. anophthalmus (11.38 %) and between K. acridorsalis and K. parvus (11.38 %) (Table 3 ). In consideration of both molecular and morphological comparisons, we confidently assign the new species to the genus Karstsinnectes .

Principal component analysis ( PCA)

The first two principal components (PCs) explained 71.1 % of the variance (Table 2 ). The first principal component (PC 1) accounted for 46.7 % of the morphological variation and distinguished variables such as body depth / SL, head lateral length / SL, caudal peduncle depth / SL, pectoral-fin length / SL, and pelvic-fin length / SL. Additionally, it separated pectoral-fin length relative to the distance between pectoral- and pelvic-fin origins and pelvic-fin length relative to the distance between pelvic- and anal-fin origins. Predorsal length / SL demonstrated a positive correlation with PC 1 scores, while predorsal length / SL exhibited a negative correlation, with factor loadings exceeding 0.60. The second factor (PC 2) accounted for 24.4 % of the morphological variation, distinguishing variables such as head width to SL, head depth to head lateral length, and head width to head lateral length, which all showed a positive correlation with PC 2 scores. Conversely, caudal peduncle length to caudal peduncle depth was negatively correlated with PC 2 scores. Scatter plot analysis revealed that species within the genus Karstsinnectes could be differentiated based on their morphometric traits (Fig. 7 ).

Figures

Figure 1. Collection sites (A), K. anophthalmus (red round), K. acridorsalis (green triangle), K. hyalinus (purple rhombus), K. longzhouensis sp. nov. (blue square), K. parvus (black star), and habitat of Karstsinnectes longzhouensis sp. nov. (B) and K. parvus (C).

Figure 5. Lateral, dorsal, ventral views, and living photo of K. parvus, neotype KIZ 2023000005 (photograph from M. Liang). Scale bar: 1 mm.

Figure 6. Bayesian phylogram of Karstsinnectes based on the mitochondrial genomes of 40 nemacheilid and two botiid species (outgroups). The numbers above the branches are Bayesian posterior probabilities (BPP %).

Figure 7. Scatter plots of first and second PCs of pooled morphometric data of Karstsinnectes.