Yunnanilus polylepis, Qin & Shao & Du & Wang, 2024

Qin, Zhi-Xian, Shao, Wei-han, Du, Li-Na & Wang, Zhen-Xing, 2024, A new species of Yunnanilus (Cypriniformes, Nemacheilidae) from Yunnan, southwest China, Zoosystematics and Evolution 100 (2), pp. 747-754 : 747-754

Yunnanilus polylepis sp. nov.

Type materials.

Holotype. KIZ 2023000009 (Kunming Natural History Museum of Zoology, KIZ, CAS), female, 43.7 mm standard length (SL), Qixitan Park , Panxi Town, Huaning County, Yuxi City, Yunnan, P. R China; Nanpanjiang River; 24.2434 ° N, 103.1221 ° E, C. S. Yang collected in November 2023 .

Paratypes. Seven specimens. KIZ 2023000010 –14, female, 31.9–37.1 mm SL, KIZ 2023000039 –40, male, 30.3–31.8 mm SL; same as holotype .

Other materials.

DLN 20230180–184, preserved in 99 % ethanol for molecular study, same as type specimens.

Etymology.

The specific name polylepis is derived from the characteristic of being entirely covered by scales Gender: Masculine. We suggest the Chinese and English common names as “ 多鳞云南鳅 ” and “ densely scaled Yunnan loach, ” respectively.

Diagnosis.

The new species is distinguished from all other members of the genus based on the following characters: whole trunk covered by scales; processus dentiformis absent; eye diameter smaller than interorbital width; nine branched dorsal-fin rays; 10 or 11 branched pectoral-fin rays; six branched pelvic-fin rays; outer gill raker absent and 10 inner gill rakers on first gill arch.

Description.

Morphometric and meristic data are given in Table 1 . Whole trunk covered with small and dense tubercles. Greatest body depth anterior to dorsal-fin origin, posterior portion gradually compressed from dorsal-fin to caudal-fin base. Head length longer than depth and deeper than width. Snout slightly blunt, shorter than postorbital length of head. Eye diameter smaller than interorbital width, posterior nostril closer to anterior margin of eye than to tip of snout; anterior and posterior nostrils separated, distance greater than diameter of posterior nostril, base of anterior nostril tube-shaped, not elongated to barbel-like (Fig. 1 I ).

Body densely scaled except for head and thorax; pectoral-fin origin to pelvic-fin origin covered by smaller and sparse scales. Upper jaw processus dentiformis absent. Three pairs of barbels, two rostral pairs and one maxillary pair; inner rostral barbel reaching posterior nostril; outer rostral barbel reaching anterior margin of eye; maxillary barbel reaching posterior margin of eye.

Dorsal fin with four unbranched and nine branched rays; origin nearer to snout tip than to base of caudal fin; pectoral fin with one unbranched and 10 or 11 branched rays (mostly 10), inserted immediately anterior to vertical through posteriormost point of operculum; pelvic fin with one unbranded and six branched rays, tips of pelvic fin not reaching anus; anal fin with three unbranched and five branched rays, origin closer to anus; caudal fin emarginate, with 15 or 16 branched rays (mostly 15). Ten inner gill rakers, without outer gill rakers on the first gill arch; lateral line incomplete, with 15–20 lateral line pores, reaching between tip of pectoral-fin and dorsal-fin origin; cephalic lateral system with 13–14 + 3 infraorbital canal pores, 7–9 supraorbital canal pores, 6–8 supratemporal canal pores, and 9–10 preoperculomandibular canal pores.

Stomach U-shaped, intestine long and straight (Fig. 2 B ). Swim bladder divided into two chambers, anterior chamber covered by dumbbell-shaped bony capsule, posterior chamber developed, connected with anterior chamber by slender tube, tube length about half of posterior chamber length (Fig. 2 A ).

Coloration.

In life, both sexes, head and trunk with grayish background color. Lower margin of eye to dorsal head surface dark brown, dorsal head with heart-shaped dark brown pattern, ventral head surface without color pattern. Predorsal trunk with five or six dark brown blotches, larger width than interspace. Four or five dark brown blotches after dorsal fin. Two elliptical, dark brown spots at base of dorsal fin, two dark brown spots at base of caudal fin. Fin rays with dark pigments, fin membrane hyaline. In females, upper line of flank with 12–14 dark brown large spots (Fig. 1 G ). In males, body with black longitudinal stripe on both sides (Fig. 1 H ). In formalin-fixed specimens, lateral stripe and blotches somewhat faded, body generally light yellow.

Distribution and habitat.

Yunnanilus polylepis sp. nov. is currently only known from Qixitan Park, Panxi Town, Huaning County, Yuxi City, Yunnan, China; Nanpanjiang River (24.2434 ° N, 103.1221 ° E). This species inhabits a deep pool with water depths ranging from 3 to 8 m, characterized by a rich presence of macrophytes (Fig. 3 ). Other fish species present in the pool include Discogobio brachyphysallidos and Sinocyclocheilus sp. Despite its confined distribution, the population of Yunnanilus polylepis sp. nov. remains stable, largely due to the enforcement of a fishing ban within the park.

Genetic comparisons.

Of the 1737 bp in combined alignment, Y. polylepis sp. nov. and Y. pleurotaenia were amplified in this study. These sequences were used for molecular phylogenetic analysis together with 34 complete mitochondrial genomes and six cyt b sequences from GenBank. Parabotia fasciata Dabry de Thiersant, 1872 and Leptobotia elongata (Bleeker, 1870) , two botiid species, were used as outgroups. Given that BI and ML analyses produced overall identical topologies, only the BI tree with Bayesian posterior probabilities (BPP) and bootstrap support (BS) values are presented here (Fig. 4 ). The phylogenetic tree strongly supports samples of Yunnanilus polylepis sp. nov. to group into Yunnanilus . Furthermore, Yunnanilus polylepis sp. nov. was identified as a sister to the clade containing Y. analis , Y. chuanheensis , Y. jiuchiensis , and Y. pleurotaenia (BPP = 1; BS = 100). However, the molecular phylogenies do not support the monophyly of Yunnanilus . Yunnanilus yangi was weakly supported to be a sister group to Eonemachilus (BPP = 59; BS = 61), and then claded together with those specimens of Yunnanilus (Fig. 4 ).

Figures

Figure 1. Morphometric characters of Yunnanilus polylepis sp. nov. A – C. Lateral, dorsal, and ventral views of female, holotype KIZ 2023000009; D – F. Lateral, dorsal, and ventral views of male, paratype KIZ 2023000041; G – H. Living photo of female and male; I. Location of anterior and posterior nostrils.

Figure 2. The air baldde (A), stomach and intestine (B), KIZ 2023000010, and tubercles on the trunk (C), KIZ 2023000011 of Yunnanilus polylepis sp. nov.

Figure 3. Type locality of Yunnanilus polylepis sp. nov. A. Distribution map; B. Habitat photo of the type locality at the time of collection.

Figure 4. Bayesian phylogram of Yunnanilus based on a concatenated dataset of mitochondrial cytochrome c oxidase subunit I (COI) and cytochrome b (cyt b) sequences. The numbers on the branches represent BPPs from BI and bootstrap supports from ML.