Oreonectes Günther, 1868

Du, Li-Na, Chen, Xiao-Yong & Yang, Jun-Xing, 2008, A review of the Nemacheilinae genus Oreonectes Günther with descriptions of two new species (Teleostei: Balitoridae), Zootaxa 1729, pp. 23-36 : 25-27

Genus Oreonectes Günther, 1868

Oreonectes Günther, 1868 : original description; type species Oreonectes platycephalus Günther, 1868 ; type locality: small stream near the top of the Hong Kong Mountains.

Diagnosis: Oreonectes is easily distinguished from other nemacheilines by its widely separated nostrils, tubular flap of the anterior nostril elongated into a barbel-like structure, and the head and caudal-peduncle compressed while the anterior portion of the body is rounded.

Percentage of caudal-peduncle length

Dorsal-fin origin Behind pelvic-fin origin In advance of pelvic-fin Behind pelvic-fin origin

origin

Caudal fin Rounded Forked Forked Eyes Absent Degenerate Degenerate

continued.

Percentage of caudal-peduncle length

The first number in parentheses is mean; second is standard deviation; - = no data.

Body elongate; head compressed; caudal-peduncle compressed; anterior portion from snout to dorsal-fin origin rounded; interorbital space broad and flat; snout depressed, shorter than the postorbital portion of the head; three pairs of barbels; anterior and posterior nostrils separated by a short distance, and tubular flap of anterior nostril elongated into barbel-like structure; mouth inferior or subterminal; lips thin and smooth; processus dentiformis absent; lower lip with median notch and completely interrupted by longitudinal groove; eyes normal, degenerate or absent; adipose crests on caudal peduncle present.

Air bladder has two chambers, anterior one within bony capsules, posterior one large and free in body cavity (except for O. platycephalus in which posterior air-bladder is reduced); intestine straight; branched anal-fin rays 5–6; branched pectoral-fin rays 10–12; branched pelvic-fin rays 6–7, or 4 in O. anophthalmus ; branched caudal-fin rays 15–16, or 12 in O. anophthalmus ; caudal fin forked, rounded or emarginate; scales rudimentary or embedded; lateral line incomplete or absent; cephalic lateral-line system present or absent, if present, with 7 preoperculomandibular, 2+2 supratemporal pores; color pattern variable: body with many spots in different shapes in O. polystigmus ; body usually plain, as in O. furcocaudalis and O. microphthalmus , or with brown basicaudal bar in O. platycephalus and O. retrodorsalis ; body transparent in O. anophthalmus and O. translucens .

Six species of Oreonectes are recognized as valid, including two new species, O. polystigmus from Dabu Village, Guilin City, and O. microphthalmus from Du’an County, Guangxi Zhuang Autonomous Region China. All morphometric and meristic characters of Oreonectes species are given in Table 1 .

Tables

TABLE 1. Morphometric and meristic characters of Oreonectes species.

Total length (mm)	O. anophthalmus , n=4 30.5–42.8(36.5+5.2)	O. furcocaudalis , n=4 52.9–72.2(56.4+16.2)	O. microphthalmus , n=6 37.9–57.7(44.7+7.3)
Standard length (mm)	25.3–36.9(31.4+4.8)	42.4–58.7(45.8+14.0)	30.8–46.9(36.4+5.9)
Dorsal-fin rays Anal-fin rays	ii, 7 ii, 5	iii, 9 iii, 6	iii,10 ii,7
Pectoral-fin rays	i, 10	i, 12	i, 10
Pelvic-fin rays Caudal fin branched rays	i,4 12	i,6 15–16	i,7 15
Percentage of SL
Body depth Head length	11.0–14.4(13.2+1.6) 22.7–24.6(23.5+0.8)	19.3–22.6(20.6+1.4) 25.7–30.2(27.4+1.8)	11.2–14.8(13.7+1.4) 28.9–30.6(29.8+0.6)
Predorsal length	59.5–62.6(60.5+1.4)	52.7–58.3(56.0+2.3)	54.7–57.9(56.1+1.2)
Caudal-peduncle length Caudal-peduncle depth	13.2–17.0(15.4+1.6) 5.7–8.7(6.9+1.3)	9.4–13.6(11.3+1.8) 5.4–7.3(6.6+0.8)	10.7–13.2(12.0+1.0) 6.3–7.5(6.7+0.4)
Percentage of HL
Snout length Eye diameter	- -	40.2–42.8(40.8+1.1) 7.1–9.9 (8.3+1.1)	37.3–39.4(38.5+0.8) 3.0–6.5(4.7+1.2)
Interorbital width	-	23.1–28.9(25.3+2.3)	18.0–23.3(21.0+1.7)
Inner rostral barbel length Outer rostral barbel length	15.0–21.5(17.6+3.0) 27.4–40.7(35.9+5.9)	17.1–25.6(21.4+3.4) 32.4–38.2(35.0+2.4)	10.6–18.8(14.2+3.0) 15.5–26.2(21.2+4.5)
Maxillary barbel length	31.1–40.8(34.8+4.4)	33.9–39.0(35.8+1.9)	11.6–30.3(20.5+6.1)
Mouth width	35.7–38.2(37.4+1.2)	25.8–29.8(28.4+1.7)	21.9–27.4(25.4+1.9)