Luciogobius huatungensis, Chen & Ren & Jiang & Wang & Chang, 2024

Luciogobius huatungensis sp. nov.

(ẼÞṣȇ)

Figures 6–9 View FIGURE 6 View FIGURE 7 View FIGURE 8 View FIGURE 9

Material examined

Holotype. NTOUP-2020-05-205 , 55.2 mm SL, coll. I-S. Chen et al., May 26, 2020, Ji-An Village , Hualien River basin, Hualian County, Taiwan.

Paratypes. NTOUP-2020-05-206 , 7 specimens, 43.3–51.2 mm SL, collection date and locality data same as above .

Diagnosis

Luciogobius huatungensis sp. nov. can be well distinguished from all other congeneric species by the following unique combination of features: (1) second dorsal fin modally I/15 and anal fin I/15; (2) pectoral fin rays modally 14 and with 4 upper, free soft rays and 1 lower free ray; (3) vertebral count: 17 + 22 = 39; and (4) specific coloration: body brown with minute creamy yellow round spots; head and body with small brown spots; belly creamy yellow with fewer brown spots; second dorsal fin with tiny white marks; and pectoral fin with several round melanophores, most membrane with brown marks.

Description

Body slender, cylindrical anteriorly and somewhat compressed posteriorly (all morphometric data is shown in Table 1 View TABLE 1 ).

Head flat and depressed. Cheek slightly fleshy. Eye somewhat small. A horizontal dermal fold with papillae row on upper part of cheek and below orbit.

Snout flat and short. Anterior nasal opening as a protruded, horizontal short tube and posterior nasal opening as a round hole. Interorbital region wide. Mouth oblique and large, maxillary extending beyond middle vertical of orbit. Lower jaw slightly prominent compared to upper jaw. Teeth rather minute, with 4–5 rows of tiny conical teeth where outer rows larger in both jaws. Tongue somewhat pointed, but anterior tip bilobed. Gill opening restricted, extending ventrally slightly below lower margin of pectoral base. Anus located in posterior half of body. Vertebral count 17 + 22 = 39.

Fins. D2 I/14–15 (modally 15), A I/15, P 14–15 (modally 14). D1 absent. D2 with middle one third portion of rays longest. A shape similar to D2. Both first spines in D2 and A relatively short. A origin about equal to D2 origin. Both rear tip of D2 and A is far from procurrent rays of C when depressed. P rounded and its length slightly shorter than postorbital length. P with four free soft rays on upper margin near upper basal and anterior region and one lower free soft ray. C elliptical. V as a round sucking disc with complete frenum and rather small.

Scales. Both body and head entirely naked without any scales.

Head lateral-line system ( Figure 5 View FIGURE 5 )

Head canals: whole head lacking any canal and head pores.

Sensory papillae: a series of infraorbital sensory papillae, typically representing a longitudinal pattern. Row a long and extending to snout which upward to surrounding eye diameter in interorbital region. Row b rather long starting above middle of dermal ridge. Row c mainly below dermal fold and long. A single cp located below rear Row c. Row d somewhat shorter than row c. Row f paired only as two papillae. Opercle with three rows ot, os, and oi. Rows oi and ot well separated. Rows z as single vertical row. Other papillae are shown in detail in Figure 5 View FIGURE 5 .

Coloration when fresh

Body and head light creamy brown to brown background. Body with minute creamy yellow round spots. Head and body with small brown spots. Head lighter on lower half. Belly pale white to creamy yellow with fewer brown spots. Second dorsal fin brown with tiny white marks. Anal fin whitish or yellowish. Pectoral fin with several round melanophores, most of fin membrane translucent with small grayish brown marks. Caudal fin brown with small creamy yellow rounded dots. Pelvic fin creamy white.

Distribution

Till present, this species is only found in both “ Hualien and Taitung ” Counties in eastern Taiwan. It can be seen as either coastal species or an inland-water species on the island. Some field collection records of the species have actually been obtained from river basins in the southern part of Taitung County, Taiwan.

Etymology

The specific name, huatungensis , refers to the type localities found in both “ Hualien and Taitung ” Counties in eastern Taiwan. The abbreviation “Huatung” is commonly used in Mandarin to refer to these two counties collectively.

Remarks

Luciogobius huatungensis sp. nov. is more similar to Luciogobius grandis Arai, 1970 than it is to any other remaining congeneric species.

However, Luciogobius huatungensis sp. nov. can be well distinguished from its closely related species, Luciogobius grandis , by the following features: (1) pectoral fin rays modally 14 vs. modally 15; with one lower free ray vs. two of them; (2) vertebral count: 17 + 22 = 39; and modally 18 + 23 = 41; and (3) specific coloration: belly less spotted vs. belly highly spotted; pectoral fin base with 4–5 large blackish brown spots and upper brownish mark vs. entirely brown background with few white spots.

Luciogobius grandis is only endemic to mainland Japan and South Korea as a template coastal species. However, Luciogobius huatungensis sp. nov. is completely different, being a subtropical species endemic to Taiwan, mainly in the eastern region. The so-called “ Luciogobius grandis ” mentioned in some previous records in Taiwanese fish guide books may have been misidentified and overlooked for this new species.