Dario tigris and Dario melanogrammus, two new species of miniature chameleon fishes from northern Myanmar (Teleostei: Badidae) Author Britz, Ralf Senckenberg Natural History Collections Dresden, Museum of Zoology, 01109 Dresden, Germany. & Research Associate, The Natural History Museum, London, SW 75 BD, United Kingdom. Author Kullander, Sven Department of Zoology, Swedish Museum of Natural History, SE- 104 05 Stockholm, Sweden. Author Rüber, Lukas Naturhistorisches Museum Bern, 3005 Bern, Switzerland. & Aquatic Ecology and Evolution, Institute of Ecology and Evolution, University of Bern, 3012 Bern, Switzerland. text Zootaxa 2022 2022-05-16 5138 1 1 16 journal article 55520 10.11646/zootaxa.5138.1.1 21c38e6d-f31a-4839-92ca-5fa5df2daaf7 1175-5326 6552095 1C7F0429-1B8C-47AC-8C00-1D6B0999A91A Dario melanogrammus , new species ( Figures 3–6 ) Holotype . BMNH 2019.10 .16.2, male, 20.4 mm SL; Myanmar , Sagaing Region , Homalin , Tarwa Chaung , 24º 52´35″N , 94º 55´56″E , 125 masl .; R Britz et al ., 23 Feb 2013 . Paratypes . BMNH 2019.10.16.3–16, 14, 14.4-22.0 mm SL; same data as holotype . BMNH 2019.10.16.94–97, 4, 16.7–18.6 mm SL; same data as holotype . BMNH 2019.10.16.98–99, 2, 16.6–17.3 mm SL; c&s, same data as holotype . NRM 64927, 13 , 14.5–19.3 mm SL. Myanmar , Sagaing Region , small stream 6 km east of Htamanthi , 25º 20´00″N , 95º 13´55″E , S. Kullander et al ., 1 Dec 2013 . NRM 65161, 22 , 12.8–16.3 mm SL. Myanmar , Sagaing Region , small forest stream, 4 km SW of Homalin , 24º 51´01″N , 94º 52´46″E , S. Kullander et al ., 27 Nov 2013 . NRM 65168, 5 , 13.5–17.4 mm SL; Myanmar , Sagaing Region , small stream across rice fields, 5 km SW of Homalin , 24º 50´42″N , 94º 52´14″E , S. Kullander et al ., 27 Nov 2013 . NRM 65208, 4 , 15.1–19.2 mm SL; Myanmar , Sagaing Region , small stream and adjacent wetland, 2km NW of Homalin , 24º 53´03″N , 94º 54´23″E , S. Kullander et al ., 26 Nov 2013 . NRM 65244, 24 , 12.2 –21.0 mm SL; Myanmar , Sagaing Region , stream outside Htamanthi village , 1 km W of Chindwin River , 25º 20´04″N , 95º 16´39″E , S. Kullander et al ., 1 Dec 2013 . NRM 65253, 29 , 11.5 –19.0 mm SL; Myanmar , Sagaing Region , swamp and small stream 5 km W of Htamanthi village , 25º 19´44″N , 94º 14´26″E , S. Kullander et al ., 1 Dec 2013 . NRM 65311, 2 , 15.2–19.2 mm SL; Myanmar , Sagaing Region , Hkamti , fish market, live purchase, 26º 00´08″N , 95º 41´43″E ; S. Kullander et al ., 30 Nov 2013 . Diagnosis. A small badid species, barely exceeding 20 mm SL, differing from all other species of Dario by its zigzagging bars, which are formed by darkly pigmented posterior scale margins involving usually three scale rows. Among Myanmar species of Dario , it can be further distinguished from D. hysginon and D. tigris by more vertebrae (modally 26 vs. modally 25 in D. hysginon , and modally 24 in D. tigris ) and a genetic divergence of 15.6–19.0 % uncorrected p -distance in the COI gene. FIGURE 3. Dario melanogrammus , BMNH 2019.10.16.2, holotype, male, 20.4 mm SL and BMNH 2019.10.16.3-16, paratype, female, 19.2 mm SL; Myanmar, Chindwin State, Tarwa Chaung near Homalin. Description. For general appearance see Figs 1–2 ; morphometric data are provided in Table 3 and meristic information in Tables 4–5 . Body elongate, moderately compressed laterally. Predorsal and prepelvic lateral profile convex. Eye situated in anterior half of head, snout short. Mouth supraterminal, directed slightly obliquely upwards with lower jaw projecting. Corner of gape situated in front of anterior margin of eye. Angle of jaws situated at vertical through anterior third of eye. Dorsal profile of body convex, ventral profile straight. Caudal peduncle only slightly tapering posteriorly. Intraoral teeth present in a marginal row anteriorly on vomer and in a circular posterior patch on parasphenoid, but absent from palatine, basihyal and hypobranchial 3. Teeth also developed on pharyngobranchials 2 and 3 and upper pharyngeal toothplate 4, as well as on ceratobranchial 5. Pharyngobranchial 1 absent. Branchiostegal rays six. Two slender supraneurals in front of first dorsal fin pterygiophore; first situated between occiput and first neural spine, second between first and second neural spine. TABLE 3. Selected morphometric characters of 10 specimens (5 males, 5 females) of Dario melanogrammus including holotype (BMNH 2019.10.16.2, BMNH 2019.10.16.3-16, values for holotype in parentheses).

Standard length (SL) in mm	14.6–21.9 (20.4)
In percent of standard length	range	mean ± SD
Head length	30.6–33.5 (32.4)	32.6 ± 0.9
Snout length	4.6–5.6 (4.4)	5.1 ± 0.4
Eye diameter	9.6–11.0 (10.2)	10.2 ± 0.5
Interorbital width	9.8–11.4 (9.8)	10.4 ± 0.5
Upper-jaw length	7.5–9.3 (9.3)	8.6 ± 0.5
Lower-jaw length	11.1–13.0 (12.7)	12.3 ± 0.6
Body depth	31.5–36.3 (35.3)	34.2 ± 1.4
Pelvic-fin length	27.3–47.1 (47.1)	34.6 ±6.9
Pelvic to anal distance	32.0–36.5 (35.8)	33.7 ± 1.8
In percent of head length
Snout length	14.3–17.2 (15.2)	15.7 ± 1.1
Eye diameter	29.5–32.7 (30.3)	31.2 ± 0.8

TABLE 4. Vertebral counts in species of the genus Dario . Modal values in bold. Information for D. tigris based on BMNH 2019.10.16.100, 2019.10.16.101-130 and MTD F-40101 that for D. melanogrammus on BMNH 2019.10.16.2, 2019.10.16.3-16, 2019.10.16.94-97, 2019.10.16.98-99, NRM 65161, 65168, 65208, and information for D. dario , D. hysginon , and D. dayingensis taken from Kullander & Britz (2002) , for D. urops from Britz et al . (2012) , for D. kajal from Britz & Kullander (2013) , D. huli from Britz & Ali (2015) and for D. neela from Britz et al . (2018) .

n=	11/14	12/12	12/13	12/14	13/12	13/13	13/14	14/12	14/13
Dario dario	50	2	2	46
D. kajal	26	3	19	2	1	1
D. hysginon	68	19	28	16	5
D. dayingensis	5	1	3	1
D. melanogrammus	50	9	6	11	24	1	1
D. tigris	37	32	5
Dario urops Dario huli	6 1	1
Dario neela	2	1
continued.
n=	14/14 14/15			24	25	26	27	28	29
Dario dario D. kajal D. hysginon	50 26 68	2 3 16	48 20 44	3 5
D. dayingensis D. melanogrammus	5 50	1 20	3 31	1 1
D. tigris	37	32	5
Dario urops	6	1	5	1	5
Dario huli	1	1
Dario neela	2	1	1	1

TABLE 5. Counts of dorsal-fin spines and rays in species of the genus Dario . Modal values in bold. Information for D. tigris based on BMNH 2019.10.16.100, 2019.10.16.101-130 and MTD F-40101, that for D. melanogrammus on BMNH 2019.10.16.2, 2019.10.16.3-16, 2019.10.16.94-97, 2019.10.16.98-99, NRM 65161, 65168, 65208, and information for D. dario , D. hysginon , and D. dayingensis taken from Kullander & Britz (2002) , for D. urops from Britz et al . (2012) , for D. kajal from Britz & Kullander (2013) , D. huli from Britz & Ali (2015) and for D. neela from Britz et al . (2018) .

n=	12/7	13/6	13/7	13/8	13/9	13/ 10	14/5	14/6	14/7	14/8
Dario dario	40	1	2	22	2	9	4
D. kajal	26	1	2	1	9	3	14
D. hysginon D. dayingensis	73 5	2	4	9
D. melanogrammus	50	1	4	1
D. tigris	37	2	1	1	10	19
Dario urops Dario huli Dario neela	16 4 14	1	3 2	1 2	7
continued.
n=	14/9	14/ 10	15/5	15/6	15/7	15/8	15/9	16/6	16/7	16/8
Dario dario D. kajal D. hysginon	40 26 73	14	4 26	1 11
D. dayingensis	5	1	2	1	1
D. melanogrammus	50	1	8	28	1	2	4
D. tigris	37	2	2
Dario urops Dario huli	16 4	11	3	2
Dario neela	14	2	2

Lateral-line canal pores present on head, absent from body. Head canal pores comprise: anguloarticular pores (aa1-aa2), preopercular pores (p1–p6), nasal pores (n1–n2), supraorbital pores (f1–f5), extrascapular pores (ex1– ex3), posttemporal pores (po1–po2), coronalis pore (cor), lachrymal pores (l1, l3); no dentary or infraorbital pores developed. Scales ctenoid on sides, cycloid on top of head. Tubed lateral-line scales absent. Scales in longitudinal row 26. Scales in transverse row 8. Circumpeduncular scales 16. Dorsal-fin lappets slightly prolonged extending slightly above spine tips, in males more so than in females; soft dorsal fin rounded, extending slightly beyond caudal-fin base in females, but to anterior third in males. Soft anal fin rounded, just reaching to caudal-fin base in females, but extending beyond caudal-fin base in males. Caudal fin subtruncate. Pectoral fin rounded with 13–14 rays, extending to third bar. Pelvic fin pointed, with medial branch of first soft ray and lateral branch of second soft ray longest. Pelvic-fin length sexually dimorphic, longest rays greatly elongated in males reaching to base of first or second anal-fin spine in males, but stopping short of vent in females. Vertebrae 12+13=25 (9), 12+14=26 (6), 13+12=25 (11), 13+13=26 (24), 13+14=27(1), 14+12=26(1). Dorsalfin spines + rays XIV+6 (1), XIV+7 (4), XIV+8 (1), XIV+9 (1), XV+6 (8), XV+7 (28), XV+8 (1), XVI+6 (2), XVI+7 (1). Anal-fin spines + rays III+7 (11), III+8 (38), and III+9 (3). Caudal-fin with 12–14 principal and 1–5 dorsal and 3–5 ventral procurrent rays: 4+6+6+3 (3), 4+6+6+4 (4), 1+7+7+3 (1), 3+7+7+3 (32), 3+7+7+4 (2), 4+7+7+3 (4), 4+7+7+4 (1), 3+7+6+4 (3), 5+8+6+5(1). FIGURE 4. Dario melanogrammus , BMNH 2019.10.16.3-16, paratype, male (A) and female (B), showing live colouration; Myanmar, Chindwin State, Tarwa Chaung near Homalin. FIGURE 5. Comparison of melanophore pattern in bars of Dario tigris , BMNH 2019.10.16.100, holotype, male, 16.7 mm SL, and D. melanogrammus , BMNH 2019.10.16.2, male, 20.4 mm SL. Note light, almost melanophore-free area at base of scales in D. melanogrammus resulting in zigzag pattern. FIGURE 6. Type locality of Dario melanogrammus , Tarwa Chaung near Homalin, Sagaing Region. Colouration in preservative. Background colour on head and body beige. Preorbital and postorbital stripes well developed, black. Dark stripe at anterior dorsal margin of opercle. A series of six vertical bars originating from base of dorsal fin and extending ventrally for up to six scale rows in abdominal area, but further ventrally to anal-fin base or ventral midline in caudal area. Another bar on caudal peduncle and an indistinct fragmented bar on caudalfin base. Dorsal, anal and pelvic fins, and base of caudal fin with dusky interradial membranes. Spinous dorsal fin, leading edges of pelvic and anal fins and ventral edge of caudal fin with whitish rim. Pectoral fin translucent. Colouration in life. Overall pattern of colour markings in specimens observed immediately after capture similar to that of preserved specimens ( Fig. 2 ) but bars less contrasted. Margin of pelvic, dorsal, anal and caudal fins bluish white in adult males. Etymology . The specific name is an adjective latinized from the Greek word μελανόγραμμος, meaning blacklined, in reference to the black zigzag lines typical of this species. Distribution and habitat. Dario melanogrammus has been collected from several localities along the Chindwin in the vicinity of Homalin, Htamanthi and Hkamti. At the type locality, Tarwa Chaung near Homalin, the water had a temperature of 24 C, a pH of 6.7 and a conductivity of 20 µS on 23 Feb 2013 . There was no aquatic vegetation and the bottom was muddy with sand and gravel. Fish species co-occuring with Dario melanogrammus include: Acanthocobitis rubidipinnis , Amblyceps sp. , Badis ferrarisi , B. kyar , Channa sp. , Danio htamanthinus , Danio sp. , Devario annandalei , Esomus sp. , Laubuka khujairokensis , Lepidocephalichthys berdmorei , Mystus pulcher , Ompok sp. , Olyra sp. , Opsarius sp. , Pethia thelys , P. meinganbii , Puntius chola , Rasbora ornata , R. daniconius , Schistura sp. , Trichogaster labiosa . Molecular data and phylogenetic analysis. The final alignment of 27 sequences of Dario ( Table 1 ) plus one outgroup was 654 bp long and the resulting ML tree is shown in Figure 8. A summary of the intra- and interspecific p-distances is provided in Table 6 . The intraspecific uncorrected p -distances ranged from 0.0–3.8%. The greatest intraspecific genetic divergence of 3.4-3.8% was encountered in Dario hysginon between the northern population from the type locality and additional locations in Kachin State , and the southern population in the Ayeyarwaddy delta with an aerial distance between them of almost 1000 km . Even the populations from the type locality and that of Lake Indawgyi showed a divergence of around 2%. Interspecific distances among the species of Dario ranged from 14.1–19.0%.