Danio htamanthinus

description

Comparative morphometry. Proportional measurements of D. htamanthinus are similar to those of D. choprae, and they differ in the same way from D. flagrans in anal-fin base length and caudal peduncle length, but D. choprae stands out with shorter barbels than D. htamanthinus and D. flagrans (Table 1). Size variation within species samples is small, and significant allometries could not be detected. Although the examined specimens of D. htamanthinus are smaller than those of D. flagrans and D. choprae, allometries may thus not influence the ratios significantly, and comparison of ratios may be useful for identification. The Principal Component Analysis (Fig. 4; Table 2) also shows separation mainly on barbel length, but also detects the short anal fin and long caudal peduncle in D. flagrans, compared with the other two species. Phylogenetic relationships. The close relationship of D. choprae, D. flagrans, D. margaritatus and D. erythromicron has already been indicated (Collins et al., 2012; Fang et al. 2009; McCluskey et al., 2015; Tang et al., 2010), although we here present the first analysis of all species together. A Bayesian analysis of relationships based on the mitochondrial C

Danio htamanthinus (Teleostei: Cyprinidae), a new species of miniature cyprinid fish from the Chindwin River in Myanmar

description

Description. General body features and pigmentation are illustrated in Figures 1 a – c. Proportional measurements are summarized in Table 1. Counts from up to 12 specimens (NRM l 1997, NRM 11998, NRM 69502). Holotype count marked with asterisk. Body compressed, elongate (body depth 26.5 – 32.0 % SL), sexes isomorphic, except for males with tubercles on pectoral fin; two specimens dissected, 16.6 and 17.9 mm SL, are females with large ovaries with ripening ova. Head laterally compressed, slightly deeper than wide. Snout short, obtuse, shorter than eye diameter. Mouth terminal, oblique in profile, jaws about equal in anterior extension. Small projection at dentary symphysis fitting into depression in upper jaw. Maxilla reaching to slightly beyond vertical from anterior margin of orbit. Lower jaw ending anteriorly slightly below middle of eye. Dentary with anterior lateral lobe with pointed tubercles; laterally a distinct band of 2 – 3 dense rows of pointed tubercles; sparse pointed tubercles medially on dentary. Holotype with row of minute tubercles in single row on adocular margin of interorbitals 2 and 3. Rostral barbel long, reaching to posterior margin of orbit or slightly beyond

Danio htamanthinus (Teleostei: Cyprinidae), a new species of miniature cyprinid fish from the Chindwin River in Myanmar

diagnosis

Diagnosis. Similar to Danio choprae and D. flagrans in general colour pattern with several vertical bars on side of abdomen; red interstripe below P + 2 stripe in life, and presence of well-developed tubercles on infraorbital ossicles. Distinguished from D. choprae and D. flagrans by absence of P + 1 stripe (vs. presence) and P stripe expressed as row of spots posteriorly on side and caudal peduncle (vs. P stripe entire). Distinguished also from D. flagrans by deeper body (26.5 % SL vs. 22.5 – 26.6 % SL), shorter caudal peduncle (17.1 – 20.5 % SL vs. 20.5 – 24.7 % SL), and longer anal-fin base (19.0 – 21.8 % SL vs. 14.2 – 18.3 % SL); from D. choprae by longer maxillary barbel (16.6 – 23.0 % SL, vs. 9.3 % SL, reaching to below pectoral-fin base adults vs. not reaching pectoral-fin base. Distinguished from all other species of Danio by characters in combination: rostral barbel present (absent in D. erythromicron, D. margaritatus, D. nigrofasciatus, D. tinwini, variable in D. rerio); mandibular barbel present (absent in D. erythromicron and D. margaritatus); lateral line absent (complete in D. absconditus, D. annulosus, D. assamila, D. catenatus, D. concatenatus, D. dangila, D. feegra

Danio htamanthinus (Teleostei: Cyprinidae), a new species of miniature cyprinid fish from the Chindwin River in Myanmar

etymology

Etymology. The specific name htamanthinus is an adjective formed on the name of the village near which the type series was collected. Geographical distribution and habitat. Danio htamanthinus is so far only known from two small streams near Htamanthi on the right bank of the Chindwin River (Fig. 2) and probably also in Shin Bway Yang further upstream in the Chindwin river basin. The type locality (Fig. 3) was a small, shallow stream with clear water, margined by low vegetation, coming out of the forest and crossing a dirt road under a bridge. Associated species were Paracanthocobitis cf. rubidipinnis (Nemacheilidae), Channa gachua (Channidae), Pethia meingangbii and P. thelys (Cyprinidae), and undetermined species of Badis and Dario (Badidae), Danio and Esomus (Cyprinidae). A second locality near Htamanthi was a flooded cleared area with stagnant clear water over grasses and a small trickle of stream feeding it (Fig. 4). Associated species here were Danio cf. quagga, Puntius chola, Pethia meingangbii, Rasbora ornata (Cyprinidae), and undetermined species of Amblyceps (Amblycipitidae) and Dario.

Danio htamanthinus (Teleostei: Cyprinidae), a new species of miniature cyprinid fish from the Chindwin River in Myanmar