Rhinogobius lithopolychroma, Li & Li & Shao & Fu & Zhou, 2024

Li, Lingzhen, Li, Chaoyang, Shao, Weihan, Fu, Suxing & Zhou, Chaowei, 2024, Two new species of freshwater goby (Teleostei, Gobiidae) from the Upper Youshui River, Chongqing, China, ZooKeys 1210, pp. 173-195 : 173-195

Rhinogobius lithopolychroma sp. nov.

Table 3 , Figs 8 , 9 , 10 , 11 , 12, 13

Type materials.

Holotype. China • 1 ♂; Chongqing City , Xiushan County; 28 ° 21 ' 21 " N, 108 ° 52 ' 16 " E; 2 July. 2023; Lingzhen Li & Chaoyang Li leg.; RL 20230001 .

Paratypes. China • Chongqing City • 6 ♂♂, 4 ♀♀; Xiushan County; 28 ° 21 ' 21 " N, 108 ° 52 ' 16 " E; 2 July. 2023; Lingzhen Li & Chaoyang Li leg.; RL 20230101 to 20230110 . • 11 ♂♂, 1 ♀; Xiushan County; 28 ° 19 ' 56 " N, 108 ° 52 ' 17 " E; 4 July. 2023 ; Lingzhen Li & Chaoyang Li leg.; RL 20230111 to 20230122 .

Diagnosis.

Rhinogobius lithopolychroma can be distinguished from other species in the Rhinogobius by the following characteristics: It typically possesses 13–15 rays on the pectoral fin. The longitudinal scale series count ranges from 30 to 33, with the predorsal area lacking scales. The total vertebrae count is 30, comprising 12 precaudal and 18 caudal vertebrae. The head and body of this species are light gray, adorned with irregular orange markings on the cheeks and opercle. Morphometrics Reference Table 3 .

Description.

Fins: The fin configuration includes 6 rays on the first dorsal fin ( VI), with a 22 total rays. The second dorsal fin consists of one spine and either 9 or 10 branched rays, totaling 15 rays. The fourth or fifth spine of the first dorsal fin is the longest and non-filamentous. In males, when the first dorsal fin is depressed, the rear tip extends to the base of the second branched ray of the second dorsal fin, while in females it reaches only to the base of the second dorsal fin anteriorly. The anal fin has 1 spine and either 7 or 8 branched rays, totaling 13 rays. The origin of the anal fin is inserted at a vertical line between the first and second branched soft ray of the second dorsal fin. The pectoral fins range from 13 to 15 rays, with 13 rays most common (present in 8 specimens), 14 rays in 13 specimens, and 15 in 1 specimen. The pectoral fins are broad in shape.

Scales: The body covered with ctenoid scales, with enlarged mid-trunk scales. The anterior predorsal area lacks scales, while the posterior part of the occipital region is covered by cycloid scales. The belly is adorned with small cycloid scales. The longitudinal scale series count ranges from 30 to 33, with a mode of 31. The transverse scale series count ranges from 7 to 9, with a mode of 8.

Head canals: pores σ are located parallel to the anterior nares. The anterior interorbital sections of the oculoscapular canal are separated, featuring paired pore λ. There is a single pore κ in the posterior region, with ω present near posterior edge of eyes and a lack of ω 1. The lateral section of anterior oculoscapular canal includes pores α and a terminal pore ρ. The posterior oculoscapular canal possesses two terminal pores θ and τ. Preopercular canals are presented, with pores ε, γ, and δ.

Sensory papillae: The sensory papillae arrangement is as follows: Row a extends to before the middle of the eye. Row b is oblique and reaches forward to the orbit. Rows c and d extend to the posterior margin of the eyes, and Row cp is absent. Row f is paired. In the opercular region, there are rows ot, oi, and os. Rows oi and ot are not connected.

Vertebrae: The total vertebrae count is 12 + 18 = 30 (N = 5) and (P – V) 3 / II II I I 0 / 9 (N = 5).

Coloration of preserved specimens: In males, the head and body are gray with irregular markings on the cheeks and operculum. The ventral side is densely covered with tiny black spots and has six large, sometimes inconspicuous, horizontal black lines. The first dorsal fin is yellowish, While the second dorsal fin is yellowish-brown. The anal fin is yellowish. Females exhibit a gray head and body, with the first dorsal fin being yellowish and displaying blue spots between the 1 st and 2 nd spiny rays. The second dorsal fin is yellowish-brown, and the anal fin is yellowish.

Colour in life: Males display a light gray head and body with irregular orange markings on the cheeks and operculum, along with three smaller orange lines along the eyes. The ventral side is densely covered with tiny orange spots and has six large, sometimes inconspicuous, horizontal black lines. The first dorsal fin shows orange outlines on spines IV – VII with a white outer edge and blue spots between the 1 st and 2 nd spiny rays. The second dorsal fin is orange with irregular blue markings internally and on the outer edge, as well as blue spots on the 1 st and 2 nd spiny rays and a wide white margin. The anal fin is orange at the base, transitioning to black with a wide white margin. Females also exhibit a light gray head and body with irregular orange markings on the cheeks and operculum, and three smaller orange lines along the eyes. The ventral side is densely covered with tiny orange spots and features six large horizontal black lines. The first dorsal fin displays orange outlines on spines IV – VII with a yellow outer edge and blue spots between the 1 st and 2 nd spiny rays. The second dorsal fin is orange, and the anal fin is orange at the base, transitioning to black with a wide white margin.

Distribution and habitat.

Rhinogobius lithopolychroma is restricted to fast-flowing, shallow streams with a cobble substrate in Xiushan, Chongqing. The surveyed streams ranged from 10 to 30 cm in depth. This goby species is characterized by its large eggs (1.5–2.1 mm in size), which it deposits on the bottom surface of the cobblestones.

Etymology.

Rhinogobius lithopolychroma was discovered in a small stream with a colorful cobble substrate. Accordingly, we named this species after its habitat. In Ancient Greek, “ litho ” means “ stone, ” and “ polychroma ” means rich in color. We combined these two words to christen this species. We suggest the Chinese name of this species as “ 彩石吻虾虎鱼 ”.

Figures

Figure 8. Dorsal (A), lateral (B), and ventral (C) views of preserved holotype of R. lithopolychroma sp. nov. (RL 20230001 male) and dorsal (D), lateral (E), and ventral (F) views of preserved paratype of R. lithopolychroma sp. nov. (RL 20230101 female).

Figure 9. The skeletal system of R. lithopolychroma sp. nov. Radiograph graphs of the whole body for paratype RL 20230201, females.

Figure 10. Dorsal (A), lateral (B), and ventral (C) views of the head of the preserved holotype of R. lithopolychroma sp. nov. Red circles indicate sensory canal pores; red dots represent sensory papillae. Abbreviations: AN, anterior nare pore; PN, posterior nare pore.

Figure 11. Photographs of R. lithopolychroma captured underwater in a tank A male and B female. Photographed by Mr Zhi.

Figure 13. Eggs of R. lithopolychroma sp. nov. at the type locality.