Rhinogobius yangminshanensis Chen & Wang & Shao 2022, new species

Rhinogobius yangminshanensis new species

(Figures. 1–5)

Materials examined.

Holotype: NTOUP-2017-06-322, 27.6 mm SL, male, July 12, 2016, coll. I-S. Chen,Yunchuenliao, Nanhuangshi, Beitou, Tanshuei River basin, Taipei City, Taiwan, ROC.

Paratypes: NTOUP-2017-06-323, 8 specimens, 27.1–31.9 mm SL, March 5, 2014, coll. Y.W. Liu, Tsaolanshi, Chitu, Keelung River, Tanshuei River basin, Keelung City, Taiwan, ROC. NTOUP-2017-06-324, 5 specimens, 24.6– 28.3 mm SL, July 12, 2016, coll. I-S. Chen, Yunchenliao, Nanhuangshi, Beitou, Tanshuei River basin, Taipei City, Taiwan, ROC. NTOUP-2017-06-325, 2 specimens, 26.2–27.9 mm SL, Aug 20, 2016, coll. I-S. Chen, Tianshiyuan, Shihlin, Tanshuei River basin, Taipei City, Taiwan, ROC. NTOUP-2017-06-326, 4 specimens, 24.8–29.6 mm SL, June 3, 2017, coll. I-S. Chen, small tributary of Tartunshi basin, Tanshuei, New Taipei City, Taiwan, ROC. NTOUP-2017-06-327, 4 specimens, 28.5–32.0 mm SL, June 4, 2017, coll. I-S. Chen, Chinshueishi, Jinshan, Huangshi basin, New Taipei City, Taiwan, ROC.

Diagnosis.

Rhinogobius yangminshanensis can be well distinguished from all other congeners by the unique combination of the following features: (1) fins: second dorsal fin rays I/9; anal fin rays I/8; pectoral fin rays modally 16; (2) squamation: longitudinal scale series 28–30 (modally 29); perdorsal scales 9–10 (modally 9); (4) vertebral count 27; (5) rear edge of mouth: merely extending to vertical of anterior margin of pupil in male and (6) specific colouration: lateral side of trunk with 6–7 longitudinal rows of bright orange to orange red spots in male which general size about 1/2 of pupil diameter. Snout with two parallel brownish gray stripes (orange one as posterior stripes in male). Cheek and opercle with 24–35 orange spots in male. Branchiostegal membrane with many minute orange spots in male. Caudal fin with distally orange zone in male with about 3 vertical rows of orange or orange red spots. First dorsal fin with broad orange band on distally 1/3 area. A middle black spot in front of the third spine of first dorsal fin in both sexes. Pectoral fin with two rows (totally 7–9 spots) of orange to red orange spots in male.

Description.

Body proportions in Table 1. Body cylindrical anteriorly, compressed posteriorly. Head rather large, somewhat depressed in male. Eye large, dorsolateral. Snout pointed. Cheek somewhat fleshy in male. Lips thick. Mouth oblique, rear edge extending near or just to vertical of anterior margin of eye in male, but not reaching vertical in female. 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, extending ventrally to vertical of rear margin of cheek. Vertebral count 10 + 17 = 27 (examined in 10 larger specimens).

Fins.— D1 VI, D2 I/8–9 (modally I/9); A I/8; P 15–17 (modally 16); 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 extending near or beyond procurrent rays of C in male. P moderate large and oblong, rear tip near 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 large ctenoid scales, anterior region of predorsal area naked; posterior dorsal area and belly cycloid. LR 29–32 (modally 30); TR 10–12 (modally 11); PreD 10–14 (modally 12); and SDP 7–8 (modally 8) (distribution frequency in Table 2). Head and prepelvic region naked. Anterior edge of midpredorsal squamation extending beyond the vertical of midline of opercle.

Head lateral-line system.— (Figure 1)

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 in lacking both with paired pore λ and pore ω. Lateral section of anterior oculoscapular canal with terminal pore α. No posterior oculoscapular canal. No preopercular canal.

Sensory papillae: Row a extending 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 well separated to lower region of row ot.

Colouration while fresh.— (Figures 2–5)

Body creamy yellow to yellowish brown. Side of body without distinct gray or brown blotches or merely with very faint gray blotches; lateral body with 6–7 longitudinal rows of bright orange to orange red spots about 1/2 of pupil diameter in male; orange brown spots less than 1/4 of pupil diameter in female. Dorsal region of body with 5–6 indistinct gray blotches.

Head creamy yellow to yellowish brown. Cheek and opercle with 24–35 orange spots in male, with small brown spots 26–30 in female. Larger cheek spot about 1/3 of pupil diameter. Nape with many orange spots in male, with small brown spots in female. Snout on dorsal side with a pair of red to brown stripe united at snout tip. Snout on lateral side with two parallel brownish gray stripes (orange one as posterior stripes in male) both terminating toward margin of upper jaw; lower one bright orange with shiny narrow blue margin in male, but brownish gray in female. Lips and dorsal snout pale brown. Branchiostegal membrane with many minute orange spots in male, but spotless in female.

First dorsal fin pale brown with broad orange band on distally 1/3 area. A middle black spot in front of third spine of first dorsal fin in both sexes. Basal region of first dorsal fin with 5–7 orange spots in male, 6–8 in female. Second dorsal fin pale with orange band on distal 1/3 region, 2–3 longitudinal rows of orange spots in male; translucent with thin gray band, 3–4 longitudinal blackish brown spots in female. Anal fin orange with distal white to gray margin. Caudal fin surrounding with distally orange zone in male accompanying with 3 somewhat vertical rows of orange or orange red spots; with pale brown zone in female accompanying with 3–4 vertical rows of small brown spots. Pectoral fin with two rows (totally 7–9 spots) of orange to red orange spots which 3–4 larger orange spots on anterior row in male; with two rows (totally 8–12 spots) of smaller brown spots in female. A bluish white band between the two rows of orange spots in male near the basal region of pectoral fin. Pelvic fin pale gray in male, whitish in female.

Etymology.—the specific name, yangminshanensis, is referred to the type locality of holotype which the tributary of Tanshuei River basin originating from the main area of Yangminshan National Park.

Distribtuion.—The new species can be found in several hill-streams of Tanshuei river basin and possibly following streams of small river basins from Gunshitanshi basin eastward along the northern coast to Marsushi basins, Shuanshi basins, in both Taipei, New Taipei cities and Taoyuan city.