Two new species of Oreias Sauvage, 1874 discovered in Son La city, Vietnam

Abstract

Oreias sonlaensis Nguyen T. H, Nguyen V. H et Hoang T. T sp.nov.

Holotype: SL.08.11.001, L = 64 mm, Lo = 57 mm collected at the lake Bom Hau, Chieng Xom commune, Son La City, at the basin of Da River.

Paratype: SL.08.11.002, L = 55 mm, Lo = 47 mm; SL.08.11.003, L = 53 mm, Lo = 45 mm; SL.08.11.004, L = 56 mm, Lo = 48 mm.

Diagnostic classification: D = 2.7; A = 2.5; P = 1.10; V = 1.5; C = 19+2. The comb is 15-16, isosceles triangle shaped. Vertebra of the whole body is 31. Lo = 5.17H = 4.19T = 8.35lcd = 9.94ccd; T = 2.86Ot = 7.73O = 2.89OO.

The body is long, quite flat narrow. Caudal edge is relatively flat and the ventral border is slightly curved. Head is medium-sized and the snout is quite pointed. Eyes are small and round with the wide and flat distance. On the head, there are two parallel and symmetrical rows of small holes from the snout end through nose, around eyes and running straight to neck. The lower snout is small. The upper lip is seamless and the lower lip is semi-concave in the middle. The upper jaw has small teeth shaped hooks. The lower jaw is spoon-shaped. There are three pairs of quite long barbels: two pair of snout barbels and a pair of jaw barbels. Dorsal fin does not have hard spines, starting the front start point of ventral fins, located among the caudal fin base and eyes. Pectoral fins of the final end is of the sharp tip. Ventral fins are small and short. The anal fin starts in the middle of the caudal fin base and the base behind the the ventral fin. The body is bare and the lateral line is complete. The ventral fin base has the isosceles triangle-shaped developed, 1/2 of the length of the fins. The swimming-bladder has two compartments: the front comparment is shaped round tube and the later is smaller and covered in the involcurum. There is no esophageal tube. Stomach is large and curved the Z shape, 1/3 of the intestine length. The intestine is 0.8 of the body length.

Color: Body is light yellowish. Along the back and the body, there are 24 dark stripes. In the middle body, there is a stripe from the rear gill cover to the tail, which is light in front and there are crossing horizontal stripes.

Distribution: Bom Hau Lake, Chieng Xom Commune, Son La City, at the basin of Da River.

Habits: Both of the species live in caves and it is rare met. In flood season, the fish will follow water to natural lakes such as Bom Hau Lake, Pu Luong Lake (Chieng Xom) and Noong Luong Lake (Chieng Den), Son La city and grow. Fish swim in soal, eating larvae, insects, pests and ants. The fish is very fat, of white fat, tasty meat, soft bones, and hardly fishy. The fish only appears in July to October; when water becomes shallow, the fish will follow water receding into caves, beds of drying lakes.

Etymology: Oreias sonlaensis was named after the place where the species was found for the first time.

Oreias trilineatus Nguyen T. H, Nguyen V. H et Hoang T. T sp.nov.

Holotype: SL. 08.11.011, L = 38 mm, Lo = 32 mm collected at Bom Hau Lake, Chieng Xom Commune, Son La City, at the basin of Da River on 09 November 2008.

Paratype: SL.08.11.012, L = 35 mm, Lo = 30 mm; SL.08.11.013, L = 38 mm, Lo = 30 mm; SL.08.11.014, L = 37 mm, Lo = 31 mm; SL.08.11.015, L = 33 mm, Lo = 27 mm; SL.08.11.016, L = 32 mm, Lo = 26 mm; SL.08.11.017, L = 34 mm, Lo = 29 mm; SL.08.11.018, L = 35 mm, Lo = 30 mm; SL.08.11.019, L = 37 mm, Lo = 31 mm; SL.08.11.020, L = 36 mm, Lo = 31 mm.

Diagnostic classification: D = 2,7; A = 1,5; P = 1,9-10; V = 1,5; C = 19+2. ctenoid with the curve I: 13-15 pieces, stick-shaped. The vertebra of the whole body is of 33-34 pieces. Lo = 4.84 H=3.16T = 8.29lcd = 9.06ccd; T = 3.17OT = 9.13O = 3.28OO.

The body has the medium length with the front flat portion and the rear flat side part. Caudal edge is bent, slightly humpbacked in the front and the ventral border is straight. Head is relatively large, length greater than height. The snout is pointed and short. Eyes are small and projected with the covering membrane. The distance between the two eyes is large. Cheek is slightly swollen. On the head, there are two parallel and symmetrical rows of small holes from the snout end through nose, around eyes and running straight to neck, round eyes and run straight through the neck. The lower mouth is small. The upper jaw has teeth-shaped physical defects. The lower jaw functions as a spoon. The upper lip is seamless and the lower lip is semi-concave in the middle. There are three pairs of quite long barbels: two pair of snout barbels and a pair of jaw barbels. Dorsal fin does not have hard spines, starting the front start point of ventral fins, nearer the caudal fin base than the snout end. Pectoral fins of the final end is slightly rounded. Ventral fins are small and short. The distance from the anal fin to the caudal fin base is larger than the distance from the anal fin to the start point of the ventral fin. The caudal fin is concave and shallow. Complete lateral line, ventral fin base have small flesh underdeveloped fin wings, 1/4 of the length of the fins. The swimming-bladder is slightly small, covered by the involcurum, two equivalent compartments. Esophageal tube length is 3/4 of the stomach. Stomach is large and curved the Z shape. Intestine is short, only 2 times longer than the stomach and equal to 0.3 of the body length.

Color: Body is pale yellowish. Along the back and the body, there are dark stripes from the back head to the tail fin base. Caudal fins have black horizontal stripes and two black bordered lobes.

Compared with other species in the Oreias: The two species are different from others in the Oreias in the fact that on their head, there are two parallel and symmetrical rows of small holes from the mouth end through nose, around eyes and running straight to neck. O. Sonlaensis sp.nov. has the straight dorsal edge, shallow ventral lines and there are horizontal stripes along back and body; the distance starting from the anal fins to the start point of the ventral fins is equal to that from the anal fins to the tail fin base; Lo = 5.17H = 4.19T; T = 2.86Ot == 7.73O = 2.89OO. Ctenoid in the curve I: 15-16 pieces, triangle-shaped and the whole-body vertebra is of 31 pieces. O. Trilineatus sp.nov. has the curved dorsal fringes, is quite humpbacked in front of back and has vertical stripes from the back head till the tail fin base; the distance from the anal fins to the start point of the ventral fins is smaller than the distance from anal fins to the tail fin base: Lo = 4.84H = 3.16T; T = 3.17Ot = 9.13O = 3.28OO; ctenoid in the curve I: 13-15 pieces, stick-shaped and vertebra in the whole body is of 33-34 pieces.

Distribution: Bom Hau Lake, Chieng Xom Commune, Son La City, at the basin of Da River.

Habits: Both of the species live in caves and it is rare met. In flood season, the fish will follow water to natural lakes such as Bom Hau Lake, Pu Luong Lake (Chieng Xom) and Noong Luong Lake (Chieng Den), Son La city and grow. Fish swim in soal, eating larvae, insects, pests and ants. The fish is very fat, of white fat, tasty meat, soft bones, and hardly fishy. The fish only appears in July to October; when water becomes shallow, the fish will follow water receding into caves, beds of drying lakes.

Etymology: Oreias trilineatus was named acording to characteristics with a line olong the back and a line in each side.