Two new species of loaches from the Irrawaddy River basin, Chin State, Myanmar (Teleostei: Cypriniformes: Nemacheilidae) Author Chen, Meng-Fang Southeast Asia Biodiversity Research Institute, Chinese Academy of Sciences, Yezin, Nay Pyi Taw 05282, Myanmar Author Myint, Khin Mar Forest Research Institute, Forestry Department, Ministry of Natural Resources and Environment Conservation, Yezin, Nay Pyi Taw 05282, Myanmar Author Chu, Ling Author Chen, Xiao-Yong Southeast Asia Biodiversity Research Institute, Chinese Academy of Sciences, Yezin, Nay Pyi Taw 05282, Myanmar text Zootaxa 2020 2020-12-14 4895 1 86 102 journal article 9300 10.11646/zootaxa.4895.1.4 6e15d95e-e470-45ed-87ac-ade99f113680 1175-5326 4321490 4FBDE3AC-2B4C-43F3-8CFD-222A9C35F44A Schistura altuscauda sp. nov. ( Fig. 10 ) Holotype . KIZ 2018002400 , 64.8 mm SL. Myanmar : Chin State : Mindat Town : Htin stream, 22°21’31”N , 94°4’28”E , 441 m elevation, Paing Zaw , Nay Htet Naing , 27 March 2018 . Paratypes . KIZ 2018002401–2403 , SEABRI 20181223, 26–30, 20181234, 48.4–73.0 mm SL; 10 specimens ; same data as holotype . Diagnosis. Schistura altuscauda sp . nov . can be distinguished from all other species in the area by a combination of the following characters: high caudal peduncle (14.0–20.3% SL), strong processus dentiformis on upper jaw; 7–19 bars on flank of body, bars in front of dorsal fin obviously thinner than those behind, sometimes fused in front of dorsal fin; lateral line complete; males with prominent suborbital flap; and pelvic lobe present. Description. General appearance and morphometric data of holotype and paratypes are shown in Fig. 10 and Table 2 , respectively. Body moderately thick, slightly increasing from nape to dorsal fins, gradually decreasing from dorsal-fin base to caudal-fin base. In lateral view, head short, eyes large, small concavity between head and body. Head with swollen cheeks, snout round, nasal valve triangular in dorsal and lateral view. Caudal peduncle depth 1.1–2.3 times its length. Developed axillary pelvic lobe. Largest known size 73.0 mm. Dorsal fin with 3 simple and 7½–8½ branched rays, distal margin slightly concave, origin anterior to pelvic-fin origin. Pectoral fin with 1 unbranched and 9–10 branched rays, reaching half distance to base of pelvic fin. Pelvic fin with 1 unbranched and 6–7 branched rays, origin between first and second branched dorsal rays, not reaching anus, which lies approximately 1.5 eye diameter in front of anal-fin origin. Anal fin with 3 simple and 5½ branched rays, not reaching caudal-fin base. Caudal fin lunate, with 9+8 branched rays. Body almost completely covered by scales, except on thorax and abdomen. Lateral line complete, 85–92 pores. Cephalic lateral line system with 8 supraorbital, 4+10 infraorbital, 10 preoperculo-mandibular, and 3 supratemporal pores. FIGURE 10. Schistura altuscauda sp. nov. , KIZ 2018002400, holotype, 64.8 mm SL; Myanmar: Irrawaddy River drainage: Htin Stream. FIGURE 11. Schistura altuscauda sp. nov. , ventral view of mouth, KIZ 2018002401, holotype, 64.8 mm SL. FIGURE 12. Schistura altuscauda sp. nov. , SEABRI S20181223, paratype, 61.1 mm SL; digestive tract. Scale bar = 1 mm. FIGURE 13. Schistura altuscauda sp. nov. , lateral view of head showing suborbital flap, KIZ 2018002401, paratype; male, 73.0 mm SL. Anterior nostril pierced on anterior side of pointed flap-like tube, forming tip and low anterior rim. Mouth shallowly arched ( Fig. 11 ). Upper lip with small incision, 11–12 deep furrows on each side. Lower lip with median interruption, 3–4 deep furrows in median area. Processus dentiformis present, wide and strong. Lower jaw exposed, without median notch. Interior rostral barbel reaching half distance to base of maxillary barbel; exterior rostral barbel reaching mouth corner. Maxillary barbel reaching vertical of posterior margin of eye. Intestine with large loop some distance behind stomach ( Fig. 12 ). Gill rakers 15–15 (1). TABLE 2. Morphometric data of holotype and paratypes of Schistura altuscauda sp . nov .

n = 11	Holotype	Range	Mean	SD
Standard length (mm)	64.8	48.4–73.0	58.2	7.7
Percentage of standard length
Total length	119.0	117.4–126.2	121.1	3.1
Dorsal head length	25.0	22.9–26.5	24.3	1.0
Lateral head length	24.3	22.0–25.9	23.4	1.0
Predorsal length	49.2	45.6–54.7	49.1	2.8
Prepelvic length	52.8	50.7–60.4	54.5	3.3
Preanal length	79.8	72.8–86.4	79.4	3.5
Head depth at eye	11.9	11.1–13.0	12.3	0.5
Head depth at nape	14.4	13.7–15.0	14.2	0.4
Body depth	22.9	18.0–25.6	22.0	2.0
Caudal-peduncle depth	16.7	14.0–20.3	16.8	1.7
Caudal-peduncle length	11.3	8.2–13.4	11.3	1.6
Snout length	12.7	10.4–12.5	11.5	0.8
Head width at nares	15.8	12.6–14.3	13.4	0.6
Head width, maximum	17.6	9.8–18.0	16.0	2.2
Body width at dorsal-fin origin	18.5	14.3–20.3	17.8	1.8
Body width at anal-fin origin	8.4	7.3–9.5	8.4	0.6
Eye diameter	4.4	3.9–4.9	4.5	0.4
Interorbital width	7.0	5.8–7.4	6.7	0.5
Dorsal-fin length	23.5	24.1–27.0	25.1	0.9
Upper caudal-lobe length	19.9	17.0–21.9	19.3	1.5
Lower caudal-lobe length	16.7	15.4–23.3	19.4	2.6
Median caudal-ray length	12.7	8.6–14.9	11.6	1.9
Anal-fin length	14.8	13.6–17.0	15.4	1.2
Pelvic-fin length	16.4	12.9–18.8	17.4	1.7
Pectoral-fin length	20.5	11.9–21.5	19.3	2.7
Percentage of dorsal head length
Snout length	50.7	41.2–51.1	47.5	3.3
Eye diameter	17.4	16.3–20.6	18.4	1.9
Interorbital width	27.9	6.5–30.6	25.5	6.6
Percentage of lateral head length
Snout length	52.3	44.6–52.6	49.2	2.7
Eye diameter	17.9	16.9–21.5	19.1	2.1
Interorbital width	28.8	26.2–31.5	28.4	1.8

Sexual dimorphism. Males possess large triangular downward suborbital flap ( Fig. 13 ). Coloration (preserved in formalin). Ground color in preserved specimens pale yellowish gray. Head with vermicular pattern on top, snout, suborbital area, and opercle. Irregular bar pattern from nape to dorsal-fin origin. 7–19 black brown bars on body, bars in front of dorsal fin obviously thinner than those behind, sometimes fused together in front of dorsal fin and wider than interspaces. 3–4 saddles from dorsal-fin base to caudal fin-base. Bars from dorsal fin-base to caudal peduncle-base meet on other side of body. Dorsal fin hyaline, with three rows of black spots. 3 black spots at dorsal midline, located at base of first unbranched ray and branched ray, third branched ray, and 4 th– 6 th branched rays, respectively. Caudal fin hyaline, with 4 rows of black spots; in paratypes , without black spots ( Fig. 14 ). Others fins hyaline. FIGURE 14. Schistura altuscauda sp. nov. , KIZ 2018002401, paratype, 73.0 mm SL; Myanmar: Irrawaddy River drainage: Htin Stream. Distribution. Schistura altuscauda sp . nov . is presently only known from the type locality, Irrawaddy River basin in Htin stream, Mindat Town, Chin State , Myanmar ( Fig. 8 ). Etymology. The name is from the Latin altus (= high) and cauda (= caudal), referring to the presence of a high caudal peduncle.