Devario myitkyinae, Kullander, Sven O., 2017

Kullander, Sven O., 2017, Devario fangae and Devario myitkyinae, two new species of danionin cyprinids from northern Myanmar (Teleostei: Cyprinidae: Danioninae), Zootaxa 4227 (3), pp. 407-421 : 414-418

Devario myitkyinae , new species

( Figs. 4–5 )

Holotype. NRM 69501, adult male, 65.8 mm SL; Myanmar, Kachin State, Ayeyarewaddy River drainage , Hpa Lap stream ca. 3 km north of Yuzana Myaing (8 km to left from Myitkyina–Myitzon road km 11), 25°32′3″N 97°23′22″E; 1 Apr 1997. F. Fang & A. Roos. (FANG-97-049).

Paratypes. CUMV 46752. 2, 48.8–78.3 mm SL. No locality data. R.W. Harrington.— NRM specimens all from Myanmar, Kachin State, Ayeyarwaddy River drainage: NRM 36362, 2 , 58–65.2 mm SL . Hpa Lap Chaung just south of Yuzana Myaing village (8 km left from Myitkyina–Myitzon road km 11), 25°31′25″N 97°22′19″E. 1 Apr 1997. F. Fang & A. Roos (FANG-97-051). — NRM 36363, 7 , 44.0– 66.3 mm SL. Hpa Lap Chaung ca. 5.6 km north of Yuzana Myaing (8 km to left from Myitkyina–Myitzon road km 11), 25°32′8″N 97°23′20″E. 1 Apr 1997. F. Fang & A. Roos (FANG-97-050). —NRM 36364, 5, 42.8–65.4 mm SL; NRM 37309, 1, 57.4 mm SL. Same data as holotype.— NRM 37290, 1 , 68.7 mm SL. Stream about 24 km on road Myitkyina–Myitzon , 25°33′46″N 97°29′30″E. 3 Apr 1997 . F. Fang & A. Roos (FANG-97-056).— NRM 40917, 2 , 46.1–61.0 mm SL. Naung Sad Chaung, isolated lake close to Ayeyarwaddy River 4 miles south of Myitkyina , 25°20′37″N 97°23′52″E. 26 Mar 1998. S.O. Kullander & R. Britz (SOK-98-020).

Diagnosis. Devario myitkyinae is similar to D. browni and D. kakhienensis in having dark horizontal stripes on side equal in width, narrow, irregular and to some extent curved away from horizontal extension. It differs from D. browni and D. kakhienensis , and also D. fangae in absence of anterior widening of the P stripe. Devario myitkyinae is further similar to species of Devario characterized by three dark stripes (P, P+1, P-1) along the side, but differs from these in having all three stripes irregular and of about equal width vs. P stripe wide and P+1 and P-1 stripes much narrower as in D. aequipinnatus , D. acrostomus , D. deruptotalea , D. fangfangae , D. fraseri , and D. gibber . In D. regina and D. malabaricus the P stripe is split anteriorly by a short light interstripe.

The status and diagnoses of D. assamensis from the Brahmaputra River in southern Assam, and D. ostreographus , without locality, are uncertain, but both were described as extremely deep-bodied, and thus unlikely to be confused with D. myitkyinae . From D. devario , D. myitkyinae can be distinguished by presence vs. absence of infraorbital process and rostral barbel; distinct vs. very shallow danionine notch; 9½–11½ vs. 15½–17½ dorsal-fin rays; 30–33 vs. 42–47 lateral line scales; 12 vs. 16 circumpeduncular scales; presence of distinct dark stripes P, P+1, P+2, P-1 P-2 on side vs. indistinct P stripe, middle and posterior side dark with scattered light spots.

From other species of striped Devario in Myanmar, D. myitkyinae is distinguished from nominal species D. affinis , D. annandalei , D. strigillifer , D. spinosus and D. yuensis by fewer scales in the lateral line (30–33, vs. 35– 53), fewer circumpeduncular scales (12 vs. 14–20), and absence of a supraorbital process; from D. xyrops in having a continuous P stripe vs. P stripe separated into two blotches; and from D. fangae by the colour pattern, characterized by up to five irregular stripes, vs. three dark, straight horizontal stripes on the middle of the side, branched dorsal-fin rays vs. 11½–13½, exceptionally, 10½, vs. 9½–10½, exceptionally 11½, and branched anal-fin rays 12½–13½, exceptionally 11½ or 14½, vs. 9½–11½.

Devario myitkyinae can be distinguished from all remaining species of Devario also by the striped colour pattern, vs. a pattern of large blotches as in D. kysonensis , D. pathirana , or smaller blotches as in D. quangbinhensis ; a very narrow posterior P stripe as in D. chrysotaeniatus , D. laoensis , D. leptos , D. micronema , D.

neilgherriensis ; vertical bars as in barred devarios D. apogon , D. apopyris , D. auropurpureus , D. interruptus , jayarami , D. maetaengensis , D. salmonatus , and D. shanensis ; uniform, with or without a thin dark stripe posteriorly on the side as in D. acuticephala and D. sondhii ; P stripe separated into two blotches as in D. anomalus ; or wide P stripe posteriorly on side, but no other dark stripes as in D. naganensis . From barred devarios, D. fraseri , and D. malabaricus , D. myitkinae can be distinguished further by presence vs. absence of infraorbital process.

Description. Based on NRM specimens. Largest female 66.3 mm SL, largest male 68.7 mm SL. Measurements are summarized in Table 3 . Counts from holotype are marked with an asterisk.

Body laterally compressed, moderately elongate. In specimens over 55 mm SL, females slightly deeper (33.2– 37.9% SL, mean 35.6% SL; N=9, 56.7–66.3 mm SL) than males (31.8–34.5% SL, mean 33.0%; N= 5, 57.4–68.7 mm SL).Predorsal contour straight or slightly curved, ascending, with slight indentation marking position of lateralis canal of temporal commissure; sloping posteriorly from dorsal-fin insertion. Prepelvic contour curved, more so in females; chest slightly compressed below pectoral fin, but not keeled. Snout short, rounded in dorsal aspect, subtriangular in lateral aspect, about as long as or slightly shorter than eye diameter in lateral aspect. Infraorbital process laminar, digitiform, with rounded tip, or broader than high, with truncate or slightly convex distal margin. Danionine notch caudally margined by blunt anteromediad projecting laminar dentary process. Skin cover absent from distal part of infraorbital process, dentary process, and anterior margin of supraorbital. Mouth terminal, obliquely directed upwards. Small knob at dentary symphysis, fitting in depression in upper jaw. Maxilla not reaching to below anterior margin of orbit. Jaws equal anteriorly; lower jaw ending anteriorly at horizontal through middle of eye, posteriorly at vertical through middle of eye. Lower jaw with large conical tubercles in band of 2–3 rows mediodorsally, band tapering to single row posteriorly, tubercles absent or small symphysially; another 1–2 rows of tubercles along medial margin of dentary. Males with strong, densely arranged sharp-tipped conical tubercles in narrow bands on anterior six branched rays of pectoral fin. Rostral barbel short, reaching base of maxillary barbel or shorter; maxillary barbel much shorter, less than half the length of rostral barbel, not reaching below middle of orbit.

Lateral line complete, along 30 (3), 31* (5), 32 (8), 33 (3) scales, and two scales on caudal-fin base; comprising one tubed scale followed by a canal running steeply caudoventrad under about five unperforated scales to slightly posterior to pectoral-fin base, where curved caudad and represented by perforated scales running in a curve parallel to the ventral body outline and ending low on caudal peduncle and caudal-fin base; continued by two scales on caudal-fin base. Median predorsal scales 13 (1), 14* (15), 15 (3). Lateral scale rows passing between dorsal and pelvic fins ½7+1+2½* (19). Circumpeduncular scale rows 12* (19). A row of scales along anal-fin base. About ¼ of caudal-fin length scaled basally.

Dorsal-fin rays iii.10 ½ (1), iii.11 ½* (9), iii.12 ½ (8), iii.13 ½ (1). Anal-fin rays iii.11 ½ (1), iii-12 ½* (8), iii.13 ½ (9), iii.14 ½ (1). Pectoral-fin rays i.10 (2), i.11 * (14), i.12 (3). Pelvic-fin rays i.7 * (19). Dorsal fin inserted at highest point of dorsum, slightly posterior to middle of body; distal margin straight, rays increasing in length to first branched ray, posterior rays gradually slightly shorter, last ray about 4/5 length of first branched ray, not reaching to middle of caudal peduncle. Anal fin inserted below anterior rays of dorsal fin; distal margin about straight, except last unbranched and first branched rays forming short extended tip; rays increasing in length to first branched ray, posterior rays gradually slightly shorter, last ray almost as long as first branched ray, reaching to middle of caudal peduncle. Pectoral-fin insertion at about vertical through posterior margin of osseous opercle; pectoral fin not extending to pelvic-fin insertion. Pectoral-fin axial lobe well developed. Pelvic fin inserted slightly anterior to midbody, not reaching to anal-fin origin. Pelvic axillary scale present. Caudal fin forked, lobes of about equal length.

Vertebrae 17+17=34 (6), 17+18= 35 (4), 18+16=34 (1), 18+17=35 (1). Pharyngeal teeth 1,3,5/5,3,2 (NRM 40917, 46.1 mm SL).

Colouration in preservative. Dorsum pale brown, sides pale yellowish white, abdomen white. Opercle pale brownish. Sides of head sparsely pigmented. Narrow dark brown middorsal stripe from occiput to end of caudal peduncle. Dark brown or black cleithral spot covering part of first lateral-line scale and scale above. Horizontal stripes brown. P stripe about one scale or less wide slightly increasing in width or equal in width from caudal to rostral end; extending from caudal fin-base rostrad, straight or irregular, to about vertical from pelvic fin insertion or tip of adpressed pectoral fin; anteriorly broken up, anastomosing with other stripes or continued as several short branches; posteriorly narrower than or equal in width to interstripe I. P+1 stripe slightly narrower or equal in width to P stripe, paralleling P stripe and equally long, narrower caudally, ending diffusely posteriorly on caudal peduncle. P+2 stripe short, not extending posterior to vertical from end of dorsal-fin base, narrower than P stripe; narrower than or equal in width to interstripe I+2. P-1 stripe parallel with P stripe, straigth or irregular, length and width equal to P stripe or narrower; narrower than interstripe I. P-2 stripe indistinct, short, on abdominal side not extending past anal fin base; narrower than or equal in width to interstripe I-1. P, P+1, P+2, P-1, and P-2 and interstripes all ending anteriorly at same vertical from pelvic fin insertion or tip of adpressed pectoral fin; colouration anterior to stripes consisting of scattered blotches and/or several narrow irregular short vertical bars. Diffuse pigmentation lighter than stripes and darker than interstripes. Dorsal and anal fins lightly pigmented, markings indistinct or absent; dorsal fin with white on tips of anterior rays; anterior caudal fin basally pale grey along middle rays, most of fin hyaline. Pectoral and pelvic fins hyaline. Young specimens less than 50 mm SL similar to adults but horizontal stripes regular, without anastomoses or disruptions.

Geographical distribution. Known only from localities close to Myitkyina on the upper Ayeyarwaddy River in Myanmar ( Fig 4 ). The 1997 other localities were small streams, up to 10 m wide, in bamboo forest with 60–80% shadow. The water was swift-flowing, clear with brown tint. The bottom consisted of mud with small stones and/or leaf litter. Associated species were identified as Danio kyathit , Oreichthys sp., Pethia didi , P. erythromycter , P. macrogramma , P. thelys , Puntius chola , Puntius sophore , Rasbora ornata , R. rasbora , Tor sp. ( Cyprinidae ), Acanthocobitis sp. ( Nemacheilidae ), Badis kyar (Badidae) , Macrognathus obscurus (Mastacembelidae) , Leiodon cutcutia (Tetraodontidae) , Mystus pulcher (Bagridae) , Notopterus notopterus (Notopteridae) , Parambassis robertsi (Ambassidae) , and Xenentodon cancila (Belonidae) . The Naung San Chaung locality was a large stagnant, shallow portion in a levee depression on the bank of the Ayeyarwaddy, with muddy bottom and surrounded by grass fields. Associated species were identified as Badis corycaeus (Badidae) , Parambassis robertsi (Ambassidae) , and Acanthocobitis mandalayensis (Nemacheilidae) .

Prashad & Mukerji (1929) reported a specimen of D. aequipinnatus from near Kamaing, which may be D. myitkyinae .

Etymology. Named for the type locality area, where this species appears to be the only representative of the genus; a noun in the genitive case.

Figures

FIGURE 4. Map of Myanmar showing collection sites of Devario fangae, D. kakhienensis and D. myitkyinae.

FIGURE 5. Devario myitkyinae. (a) holotype, NRM 69501, male, 65.8 mm SL; (b) paratype, NRM 36363, male, 61.8 mm SL; (c) paratype, NRM 36364, female, 56.7 mm SL. All from Myanmar: Kachin State, Ayeyarwaddy River drainage, Hpa Lap Chaung near Myitkyina.

Tables

TABLE 3. Morphometry of Devario myitkyinae (NRM 36362 – 36364, 37290, 40917). Measurements are in percent of standard length (SL), except for standard length, in mm. Correlation (Pearson’s r), and linear regression parameters (y = a + b * SL) were calculated from original measurements in mm, and are given only where r ḵ 0.9; SD = standard deviation. HT = holotype.

	HT	n	min	max	mean	SD	a	b	r
SL (mm)	65.8	19	42.8	68.7	58.1	7.7
Body depth	33.7	19	31.8	37.9	34.7	1.9	2.836	0.297	0.95
Head length	25.2	19	23.7	27.1	25.4	1.0	3.029	0.201	0.99
Snout length	7.3	19	6.7	8.5	7.4	0.4	0.548	0.064	0.98
Head depth	19.8	19	14.4	21.4	18.6	1.5	1.851	0.154	0.96
Head width	13.2	19	12.4	14.6	13.3	0.7	1.243	0.112	0.99
Upper jaw length	9.1	19	8.4	11.5	9.8	0.8	2.151	0.060	0.96
Lower jaw length	12.2	19	11.0	14.3	12.5	1.0	3.083	0.071	0.97
Orbit diameter	8.4	19	7.8	10.2	8.8	0.6	2.160	0.050	0.95
Interorbital width	11.7	19	10.5	12.3	11.3	0.5	1.395	0.089	0.98
Caudal-peduncle length	17.6	19	14.8	18.8	16.8	1.1	-0.930	0.184	0.93
Caudal-peduncle depth	14.0	19	12.1	14.1	13.1	0.6	-0.461	0.139	0.99
Dorsal-fin base length	22.3	19	19.1	22.3	20.8	0.9	-0.194	0.211	0.91
Aanal-fin base length	20.7	19	18.2	22.9	20.1	1.1	-0.295	0.206	0.96
Predorsal length	57.6	19	57.6	62.5	59.7	1.1	2.368	0.555	0.99
Preanal length	67.3	19	66.1	71.8	68.8	1.6	3.926	0.619	0.99
Prepelvic length	47.3	19	46.0	52.7	49.6	1.8	4.305	0.421	0.99
Pectoral-fin length	21.7	19	20.1	25.2	23.0	1.6	5.430	0.135	0.95
Pelvic-fin length	16.1	19	14.0	16.8	15.7	0.7	1.960	0.122	0.95
Rostral barbel length	4.7	19	3.5	5.6	4.7	0.5
Maxillary barbel length	1.8	19	1.2	2.3	1.7	0.3