15/06/2014

Loài cá mới ở sông Kỳ Cùng Opsariichthys duchuunguyeni

Loài cá Opsariichthys duchuunguyeni (Ảnh Journal of Marine Science and Technology, Vol. 21, Suppl., pp. 135-145 (2013) 135. DOI: 10.6119/JMST-013-1219-12)
Description
Body proportions listed in Table 1. Body elongated and compressed laterally, body depth slightly longer than head length. Body width rather narrow. No maxillary barbels. Mouth oblique, maxillary extending to or slightly beyond ver- tical of anterior margin of orbit. Eyes rather large. Upper lip slightly concave but not notched. Breeding tubercles distinct on head and anal rays of adult male, the area below lower jaw with two rows of totally 12-15 rounded tubercles, cheek with 3 longitudinal rows of tubercles which has the lower row 
separated and located at below of cheek while the rest with two rows positioned just below margin of orbit and the upper row of tubercles interrupted. Gill rakers 2+6 (5 specimens). Pharyngeal teeth arranged into two to three rows: 5-4-1; 1-4-4 or 4-4-1; 1-4-4 or 5-4; 4-4. Vertebrae count 4+16+20-4+ 16+21 (40-41). 
Fins 
Dorsal fin rays iii,7; anal fin rays iii,9; pectoral fin rays i,14-15; pelvic fin rays i,7-8. Pelvic fin origin vertical dorsal fin origin. Pectoral fin almost reaching pelvic fin in adult male, shorter in juvenile male and female. Pelvic fin margin roundish and extending to anal fin origin in adult male. Anal fin with first four elongated branched rays. Caudal fin forked, lower lobe slightly longer than upper one. Frequency distribution of meristic counts is provided in Table 2. 
Scales 
Body with moderately cycloid scales. Lateral-line complete, depressed downward above pectoral fin and extending along lower half of body to mid-lateral on caudal peduncle. Lateral- line scales 41 (5 specimens); scale series above lateral-line 8; scale series below lateral-line scale 3; pre-dorsal scales 13-14; anterior scales to pelvic fin 13-14; and scales surrounding caudal peduncle 17. Belly with tiny scales. 
Etymology 
The specific name, duchuunguyeni, honors ichthyologist, Prof. Nguyen Huu Duc, who has contributed for Vietnamese freshwater fishes research. 
Distribution 
The new species was found from the streams running to Bang Giang river (Cao Bang province) and Ky Cung river (Lang Son province) themselves are tributaries of Pearl river. 
Habitat 
This species lives in upper reach of stream with moderate velocity of clear water on the benthic substratum of small and medium pebbles and boulders
Theo Journal of Marine Science and Technology
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