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

Luciogobius chaojinensis sp. nov.

(AE境ṣȇ)

Figures 1–3 View FIGURE 1 View FIGURE 2 View FIGURE 3

Material examined

Holotype. NTOUP-2006-05-321 , 30.2 mm SL, May 16, 2006, coll. I-S. Chen et al., Chaojin Park, Keelung City, Taiwan.

Paratypes. NTOUP-2006-05-322 , 2 specimens, 24.1–27.0 mm SL, collection date and locality data same as above .

Diagnosis

Luciogobius chaojinensis sp. nov. can be well distinguished from the other congeneric species by the following unique combination of features: (1) second dorsal fin rays: I/10 and anal fin rays I/11; (2) pectoral fin rays modally 13 and with one upper, short free soft ray; (3) vertebral count: 20 + 21 = 41; and (4) specific coloration: head and body with small tiny blackish brown spots. Head with densely-set small blackish brown spots in male; second dorsal fin brown and darker on lower half; pectoral fin base on upper 1/2 region with round melanophores; and pectoral fin membrane mostly spotless.

Description

Body very slender, cylindrical anteriorly and somewhat compressed posteriorly (all morphometric data is shown in Table 1 View TABLE 1 ). Head flat and depressed. Cheek rather fleshy in male. Eye very 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 very oblique and rather large, maxillary extending beyond rear vertical of orbit in male. Lower jaw rather 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 rather restricted, extending merely slightly below lower margin of pectoral base. Anus located in posterior half of body. Vertebral count 20 + 21 = 41.

Fins. D2 I/10, A I/11, P 12–13 (modally 13). 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 in front of D2 origin. D2 origin inserted vertically between 3rd and 4th branched rays of A. Both rear tip of D2 and A far from procurrent rays of C when depressed. P rounded and its length much shorter than postorbital length. P with one free soft ray on upper margin near upper basal region. C elliptical. V as a very reduced, round sucking disc with complete frenum.

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

Head lateral-line system ( Figure 2 View FIGURE 2 )

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 slightly behind middle vertical of eye, its length about two times eye diameter. Row c mainly below dermal fold and long. A single cp located below rear Row c. Row d 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 2 View FIGURE 2 .

Coloration when fresh

Body and head light yellowish to deep brown background. Head and body with small tiny blackish brown spots. Entire head with densely-set small blackish brown spots in male. Belly yellowish or pale white; golden ovary seen in female. Second dorsal fin brown and darker on lower half. Anal fin whitish or pale yellowish. Pectoral fin base on upper 1/2 region with several small round melanophores in male and mostly pectoral fin membrane translucent and spotless. Caudal fin entirely brown to blackish brown and lacking any light rounded spot. Pelvic fin translucent and pale white.

Distribution

Till present, this new species is endemic to the Chaojin Park, Keelung City in northern Taiwan. It is a coastal species of Taiwan. However, it is still quite possible to find it in other localities in northern Taiwan, even though it may be largely confined to Taiwanese waters.

Etymology

The specific name, chaojinensis , refers to the type locality from the “Chaojin Park”, a famous marine conservation zone in Keelung City in northern Taiwan.

Remarks

Luciogobius chaojinensis sp. nov. is more similar to Luciogobius opisthoproctus Chen & Liao, 2024 than it is to any other congeneric species.

However, Luciogobius chaojinensis sp. nov. can be well distinguished from the closely related species, Luciogobius opisthoproctus , by the following features: (1) anal fin rays I/11 vs. I/12; pectoral fin rays 13 vs. modally 11; (2) pectoral fin with one upper free rays vs. none of them; (3) vertebral count: 41 vs. modally 43; and (4) specific coloration: head in lateral side with densely-set of small brown spots superficially (around 60–95, higher count in male) vs. with very few brown to black spots (8–10); pectoral fin base: in having several brownish black spots vs. entirely spotless.

It is quite possible that we will see more undescribed species with a slender form in the cryptic habitats of Taiwanese waters in the near future.