Threatened fishes of the world: <em>Diptychus maculatus</em> and <em>Aspiorhynchus laticeps</em>

Abstract

In order to deeply analyze the individual biological characteristics of unique fish in China, lay a solid foundation for the effective protection of its germplasm resources, and further enrich and consolidate the basic biological data system of endemic fish in the world. According to the ethical norms and fishing licenses, 5 samples of Diptychus maculatus and 3 samples of Aspiorhynchus laticeps were collected from the Tarim River system in Baicheng County from 2023 to 2024. The morphological characteristics, age identification and anatomical observation of the two fishes were analyzed by classical biological methods. Both fish belong to Cypriniformes, Cyprinidae, Schizothoracinae. D. maculatus has a long body, a conical head, and a lower mouth with a pair of fish whiskers. The mouth is slightly blunt and arcuate, and the lateral line is complete. A. laticeps has a long, slightly flattened body, a round abdomen, and a large head that is flattened at the front. It also has a pair of fish whiskers located at the corners of the mouth. Age identification materials: D. maculatus lapillus 6+, asteriscus 6+, vertebra 6+, anal scales 6+, opercular bone 5+, A. laticeps lapillus 7+, asteriscus 7+, vertebra 7+, anal scales 7+, opercular bone 7+. The peritoneal wall of D. maculatus is black or brown the tooth type was 3·4-4·3; the external behavior of gill rakers was 8-13; and the internal behavior was 12-16. A. laticeps pharynx teeth 3 lines, tooth type is 2·3·5-5·3·2; the external behavior of gill rakers was 11-13; and the internal behavior was 15-18. D. maculatus and A. laticeps are special species distributed in the Tarim River system. Their evolutionary adaptation is closely related to the uplift of the Qinghai-Tibet Plateau. This study provides important data for better understanding the individual biological characteristics of these two endangered fish species and lays the foundation for their germplasm resource conservation.