Rhinogobius dongfongensis, Chen & Wei, 2024

Rhinogobius dongfongensis n. sp.

(ƍDz吻ṞẊ)

( Figs. 1–3 View FIGURE 1 View FIGURE 2 View FIGURE 3 )

Materials examined

Holotype. —NTOUP-2003-05-321, 42.9 mm SL, coll. I-S. Chen & J.W. Wang, May 12, 2003, Dongfong township, Jian-Ou City, a small tributary of Minjiang River basin, Fujian Province, PRC.

Paratype.—NTOUP-2003-05-322, 36.1 mm SL, collection date and other data same as holotype.

Diagnosis

Rhinogobius dongfongensis n. sp. which collected from northern region of Fujian Province, China can be well distinguished from all other congeners by the unique combination of the following features: (1) fins: second dorsal fin rays I/8–I/9; anal fin rays I/7; pectoral fin rays modally 15; (2) squamation: longitudinal scale series 32–33 (modally 33); perdorsal scales usually 5–6; (3) normal vertebral count 26; (4) rear edge of mouth: merely extending to vertical of anterior margin of pupil in male and (5) specific colouration: side of body light brown to pale brown with about 6–7 clusters of net-like black marks along middle horizontal series; dorsal region of body with 6–7 indistinct gray blotches; cheek and opercle with densely-set rather tiny 160–170 blackish brown spots in male; second dorsal fin translucent as pale brown tone with 6–7 longitudinal rows of tiny blackish brown spots; and pectoral fin basal region with a cluster of small brown spots on upper 2/3 region.

Description

Body proportions in Table 1 View TABLE 1 . Body rather slender, cylindrical anteriorly, compressed posteriorly. Head moderate large, rather depressed anteriorly in male. Eye large, dorsolateral. Snout pointed. Cheek rather fleshy in male. Lips thick. Mouth oblique, rear edge extending beyond vertical of anterior margin of eye in male. Both jaws with 3–4 rows of conical teeth, outer jaws enlarged. Tongue margin rounded. Anterior nostril in short tube and posterior nostril round. Gill opening small and restricted, extending ventrally to vertical midline of opercle. Vertebral count 10 + 16 = 26.

Fins.— D1 VI, D2 I/8–9;A I/7; P 15–16 (modally 15); V I/5+I/5 (distribution frequency in Table 2). D1 rounded, 3 rd and 4 th rays slightly longer, with rear tip while depressed extending beyond D2 origin in male. Origin of A inserted below second branched rays of D2. Rear tips of D2 and A fin rays not extending to procurrent rays of C in male. P moderate moderate large and oblong, rear tip not reaching vertical line through anus in male. V small and rounded, spinous rays with somewhat pointed membrane lobe. C elliptical, rear edge rounded.

Scales.— Body with moderately size ctenoid scales, anterior region of predorsal area naked; posterior dorsal area and belly cycloid. LR 32–33 (modally 33); TR 11; PreD 5–6; and SDP 11–12 (distribution frequency in Table 2). Head and prepelvic region naked. Anterior edge of midpredorsal squamation restricted, not extending to the vertical of midline of opercle.

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

Canals: Nasal extension of anterior oculoscapular canal with terminal pore σ located in between anterior and posterior nostrils. Anterior interorbital sections of oculoscapular canal with paired pore λ. A single pore κ in near rear of interorbital region also with paired pore ω. Lateral section of anterior oculoscapular canal with terminal pore α. Posterior oculoscapular canal with two terminal pores θ and τ.

Sensory papillae: Row a extending forward beyond vertical midline of orbit. Row b length about equal to eye diameter. Rows c, d longer. A single cp papilla. Row f paired. Anterior edge of row oi somewhat connecting to lower region of row ot.

Colouration while fresh.—( Figs. 1 View FIGURE 1 , 3 View FIGURE 3 )

Body yellowish brown to grayish brown. Side of body light brown to pale brown with about 6–7 clusters of net-like black marks along middle horizontal series. Dorsal region of body with 6–7 indistinct gray blotches.

Head yellowish brown to brown. Cheek and opercle with densely-set rather tiny 160–170 blackish brown spots in male. Anterior part of nape to interorbital region with densely-set, rather tiny blackish brown spots in male. Snout on dorsal side with a pair of blackish to pale brown stripe united at snout tip. Snout on lateral side with an infraorbital pale brown stripe turning vertical ventrally terminating half way above upper lip in male.

Lips and dorsal snout pale brown. Branchiostegal membrane gray with some outer short, parallel brown bars separating light spots in male.

First dorsal fin translucent as pale brown tone with grayish fin membrane, and a small black spot in front of its second spine on lower half of fin membrane. Second dorsal fin translucent as pale brown tone with 5–6 longitudinal rows of tiny blackish brown spots and with narrow distal margin. Anal fin pale to grayish white with distal white margin. Caudal fin translucent to pale white with 7–9 vertical rows of blackish brown spots. Its basal region with a middle conspicuous but small deep black spot. Pectoral fin pale brown and its basal region with a cluster of small brown spots on upper 2/3 region. Pelvic fin grayish black in male.

Etyomolgy

The specific name “ dongfongensis ” is referred to the type locality of current species occurring around the area of “Dongfong” township as a small tributary of Minjiang River basin, Fujian Province, PR China.

Distribution

The new species is endemic species in fresh waters of the tributary of Minjiang basin, Fujian Province in mainland China. The distribution range of the species may be very restricted.

Remarks

The new species, Rhinogobius dongfongensis is rather similar to Rhinogobius multimaculatus (Wu & Zheng, 1985) in Zheng & Wu 1985 by cheek as highly spotted pattern with over 100 blackish brown spots than any other congeneric fluvial species around mainland China. However, Rhinogobius dongfongensis can be clearly distinguished from Rhinogobius multimaculatus by the several following features: (1) pectoral fin rays: modally 15 vs. 17; (2) second dorsal fin rays I/8–9 vs. modally I/10; (3) longitudinal scale rows usually 33 vs. 37; and (4) vertebral count 26 vs. 29. In addition, the former species is merely endemic to northern region of the Minjiang River basin, Fujian Province; the later species is only endemic to upper reaches of the Jaoshi River basin, northern region of Zhejiang Province from mainland China.

Furthermore, the unpublished mitogenetic data of current species and all remaining undescribed or related nominal fluvial species of Rhinogobius species is still processing to make a resolution of evolutionary puzzle for them, the molecular phylogenetic analysis for those species may provide the more detail evolutionary history and establishing some hypothesis for speciation pattern in near future (Chen, unpublished data).