Formosania immaculata Sun, Zhou & Yang, 2023

Sun, Wei, Zhou, Jia-Jun & Yang, Jin-Quan, 2023, Formosania immaculata, a new species of hillstream loach (Teleostei, Cypriniformes, Gastromyzontidae) from the Ou-Jiang River, Southeast China, ZooKeys 1182, pp. 207-221 : 207

publication ID	https://dx.doi.org/10.3897/zookeys.1182.104240
publication LSID	lsid:zoobank.org:pub:39A9DC67-106B-42E1-B5BA-9F06DDA42CB3
persistent identifier	https://treatment.plazi.org/id/E62FDC2E-148C-45B3-8BC1-2AD18C2B486A
taxon LSID	lsid:zoobank.org:act:E62FDC2E-148C-45B3-8BC1-2AD18C2B486A
treatment provided by	ZooKeys by Pensoft
scientific name	Formosania immaculata Sun, Zhou & Yang
status	sp. nov.

Treatment

Formosania immaculata Sun, Zhou & Yang sp. nov.

Figs 1 View Figure 1 , 2A View Figure 2 , 5 View Figure 5

Type material.

Holotype. SHOU2021060325, 87.9 mm total length (TL), 77.4 mm standard length (SL), adult collected by Jia-Jun Zhou and Wei Sun on June 28, 2021, in Wuyi County, Jinhua City, Zhejiang Province, China (28.7179°N, 119.4939°E; c. 882 m a.s.l.).

Paratypes. Twelve specimens from the same locality as the holotype, SHOU2021060326-060337, 43.2-68.7 mm SL, were collected by Wei Sun and Jia-Jun Zhou on June 28, 2021.

Description.

Morphometric measurements for the specimens examined are given in Table 2 View Table 2 . See Fig. 1A-C View Figure 1 for lateral, dorsal, and ventral views of the body and Fig. 2A View Figure 2 for its mouthpart structures.

Head depressed in lateral view; head width always greater than depth; head width 17.4-19.7% of SL. Snout obtuse in dorsal view and longer than postorbital length; snout length 114.5%-125.0% of postorbital length. Mouth inferior and arched. Lips fleshy, with upper lip wide, without obvious convex particles; lower lip with a pair of papillae and a pair of lobulated papillae (Fig. 2A View Figure 2 ). Upper lip connected to lower lip around the corners of mouth by a papillated flap and one pair of maxillary barbels at the corners of mouth. Upper jaw covered by upper lip. Rostral fold appeared at end of snout, with 13 well-developed rostral barbels in an irregular row, covered with small spots. All rostral barbels connected with rostral fold. Outermost pair of rostral barbels longest and slightly longer than eye diameter, with a length of 112.9%-140.0% of eye diameter. Anterior and posterior nostrils adjacent with a well-developed flap on anterior ones. Eyes normal; diameter 13.7%-16.8% of HL. Gill openings reached ventral surface of head, with its upper extremity reaching the level of upper margin of orbit. Body elongated, the anterior part of body cylindrical and laterally compressed behind dorsal-fin base. The greatest depth of body at dorsal-fin origin and the least depth at caudal-fin base; body depth at dorsal-fin origin 16.1%-21.1% of SL. Body scaled but scales absent on head and before the middle of pectoral-fin base of abdomen. Scales minute, lateral line complete with 92-98 perforated scales. Caudal peduncle compressed laterally; length equal to peduncle depth.

Dorsal fin had three unbranched and eight branched rays; origin slightly in front of pelvic-fin insertion, situated slightly ahead to the midpoint between snout tip and caudal-fin base. Pectoral fin developed, with one unbranched and 13-14 branched rays. Pelvic fins long with one unbranched and eight branched rays, tips of depressed pelvic fins reaching anus when pelvic-fin rays extended backward. Anus in middle of pelvic-fin insertion and anal-fin insertion; anal fin with two unbranched and five branched rays, with the tip of anal fin closing or reaching to caudal-fin base. Caudal fin slightly forked; lower lobe slightly longer than upper lobe.

Coloration. In life, body slightly brown; fins and rostral barbels slightly red; with inconspicuous black blotches on back of head (Fig. 5 View Figure 5 ). In 10% formalin-fixed specimens, dorsal and flank of head and body grayish-brown; ventral surface of head and abdomen white to yellowish with many black spots after pectoral fins; all fins hyaline and light gray, without obvious blotches (Fig. 1 View Figure 1 ).

Diagnosis.

Formosania immaculata sp. nov. resembles the Formosania davidi species group ( F. davidi , F. galericula and F. fasciolata ) in having 13 well-developed rostral barbels arranged in one irregular row (Fig. 2A View Figure 2 ), while other congeners arranged in 2 rows (Fig. 2B View Figure 2 ). It is distinguished from the three species in the Formosania davidi species group by having no obvious blotches or stripes (vs. having blotches or stripes) on the body and snout length longer than (vs. equal to) postorbital length (see Fig. 3 View Figure 3 and Table 3 View Table 3 ). The new species differs from F. davidi in having shorter rostral barbels [outermost pair 112.9%-140.0% (average 122.2) vs. 128.3%-175.4% (average 159.0%) of eye diameter], shorter lower lip papillae [19.9%-24.4% (average 22.8) vs. 47.0%-61.9% (average 53.0%) of eye diameter] and narrower abdominal scaleless area (extending to middle of pectoral-fin base vs. extending slightly behind pectoral-fin axil) (see Table 3 View Table 3 ); from F. fasciolata in having shorter rostral barbels [outermost pair 112.9%-140.0% (average 122.2) vs. 119.8%-167.5% (average 145.6%)] of eye diameter, shorter lower lip papillae [19.9%-24.4% (average 22.8) vs. 40.3%-51.0% (average 47.0%) of eye diameter] and shorter depth of caudal peduncle [91.0%-101.9% (average 97.8%) vs. 107.9%-130.6% (average 118.8%) of caudal peduncle length]; and from F. galericula in having narrower abdominal scaleless area (extending to middle of pectoral-fin base vs. extending slightly behind pectoral-fin axil).

Etymology.

The specific epithet is the Latin form of the word immaculate here referring to the unique body of no blotches or stripes. We propose the Chinese common name Wú Bān Yīng Kǒu Qiū (无斑缨口鳅).

Distribution and habitat.

The new species is known only from the upper reaches of the Xuanping-Xi, a stream tributary to the Ou-Jiang River, in Wuyi County, Zhejiang Province, China (Fig. 4 View Figure 4 ). It inhabits fast-flowing streams with gravelly and pebbly substrates (Fig. 5 View Figure 5 ).