Triplophysa xuanweiensis sp. nov., a new blind loach species from a cave in China (Teleostei: Cypriniformes: Nemacheilidae)

Two new hypogean species of the genus Triplophysa (Osteichthyes, Cypriniformes, Nemacheilidae) from Guizhou Province, Southwest China, with underestimated diversity

Two new species of the genus Triplophysa from southwestern Guizhou Province, China, are described. These are Triplophysaziyunensis Wu, Luo, Xiao & Zhou, sp. nov. and Triplophysayaluwang Lan, Liu, Zhou & Zhou, sp. nov. from Maoying Town, Ziyun County, Guizhou Province, China. Triplophysaziyunensis Wu, Luo, Xiao & Zhou, sp. nov. is distinguished from other hypogean species of the genus Triplophysa by having a combination of the following characteristics: body naked, scaleless, pigmented markings on surface of body, except ventral; eyes reduced, diameter 2.4-4.9% of head length; pelvic-fin tip extending to anus; tip of pectoral fin not reaching pelvic fin origin; anterior and posterior nostrils closely set, with anterior nostril elongated to a barbel-like tip; tip of outrostral barbel extending backward, not reaching anterior margin of the eye; lateral line complete; posterior chamber of air bladder degenerated; and fin differences. Triplophysayaluwang Lan, Liu, Zhou & Zhou, sp. nov. is distinguished from other hypogean species of the genus Triplophysa by having a combination of the following characteristics: body naked, scaleless, with irregular pale and dark brownish brown markings, except ventrally; eyes reduced, diameter 4.6-6.1% of head length; pelvic-fin tip reaching anus; tip of pectoral fin not reaching to pelvic fin origin; anterior and posterior nostrils closely set, with anterior nostril elongated to a barbel-like tip; tip of outrostral barbel extending backward, not reaching to anterior margin of the eye; lateral line complete; posterior chamber of air bladder degenerated; and fin differences. Mitochondrial Cyt b revealed relatively small genetic differences, 1.4-2.0%, between the two new species and close relatives. Nuclear gene RAG1 indicated that the two new species possessed unique haplotypes with multiple linking mutations. This study emphasizes the importance of utilizing nuclear genes to identify new species in rapidly speciation cave species, with small genetic differences due to mitochondrial introgression occurring interspecies.

Age, growth, and energy storage of the subterranean fish Triplophysa rosa (Cypriniformes: Nemacheilidae) from Chongqing, China

BACKGROUND

This study explores the age, growth, and energy storage of Triplophysa rosa, a troglobitic cavefish. A total of 102 wild T. rosa specimens were collected in Wulong County, Chongqing, China, between 2018 and 2022, with otoliths used for age determination.

RESULTS

The earliest mature individuals were determined to be 4.8 years old, while the maximum ages for females and males were estimated at 15.8 years and 12.2 years, respectively. The length (L, cm)-weight (W, g) relationship was found to be the same for both sexes, following the eq. W = 0.0046 L3.03. Von Bertalanffy growth models were applied to the total length-at-age data, resulting in an asymptotic length of 23.4 cm and a K-parameter of 0.060 year-1. The body content of protein, ash, and glycogen did not show a significant correlation with the total length of T. rosa. However, both lipid and energy content exhibited a significant increase with total length. The lipid content ranged from 40.5 to 167.1 mg g-1, while the energy content ranged from 4.50 to 11.39 kJ g-1, indicating high storage features of T. rosa.

CONCLUSIONS

The results affirm that T. rosa exhibits life traits conducive to its population dynamics in cave conditions, characterized by slow growth, small size, and high lipid energy storage.

Triplophysadaryoae, a new nemacheilid loach species (Teleostei, Nemacheilidae) from the Syr Darya River basin, Central Asia

Triplophysadaryoae, new species, is described from the Sokh River, a former tributary of Syr Darya that today fails to reach the river, in the Sokh District, an exclave of Uzbekistan, surrounded by Kyrgyzstan. Triplophysadaryoae is distinguished from other species of Triplophysa in Central Asia by a truncate caudal fin with 13 or 14 branched rays, body without obvious mottling, dorsal-fin origin opposite to pelvic-fin insertion, and absence of the posterior chamber of the air bladder. Molecular data suggest that Triplophysadaryoae is closely related to T.ferganaensis from the Shakhimardan stream, a small tributary of Syr Darya in the Yordon village, another exclave of Uzbekistan in Kyrgyzstan. The two species were separated by a Kimura 2-parameter genetic distance of 2.8% in the mitochondrial DNA cytochrome c oxidase subunit I barcode region; they are also distinguished morphologically. A key to the species of Triplophysa in the Syr Darya basin and adjacent regions is provided.