Devario anomalus

description

Description. General body shape as in Figures 1 and 2. Morphometric and meristic data provided in Tables 1 and 2. Head and body compressed. Body depth greatest at pelvic-fin origin. Dorsal body surface profile slightly more rounded than ventral body surface profile. Snout short, slightly greater in length than eye diameter. Mouth supraterminal. A large, rounded symphysial knob present on lower jaw, fitting into shallow groove on inner margin of upper jaw with mouth closed. Two pairs of barbels. Rostral barbels reaching to or slightly past anterior margin of orbit. Maxillary barbels short, less than half as long as rostral barbels. A large anterior indentation (danionin notch, sensu Roberts, 1986) present along ventromedial edge of dentary. Infraorbital process present on posterior edge of IO 1. Anteroventralmost point of supraorbital entering orbit. Dorsal surface of head with well developed skin grooves along supraorbital shelves. A single row of small, conical tubercles present along upper margin of lower jaw. holotype range mean st. dev. Standard length (mm) 71.6 69.2 – 81.0 Dorsal fin with iii. 11 (2) or iii. 12 (4) rays. Anal fin with iii. 13 (3) or iii. 14 (3) rays. Principal

Devario anomalus, a new species of freshwater fish from Bangladesh (Ostariophysi: Cyprinidae)

diagnosis

Diagnosis. A large species of Devario, distinguished from all other species of the genus by its unique colour pattern, consisting of 5 – 8 dark, irregular, vertical bars, restricted to the anterior half of the body and widely separate from a short, broad P-stripe, originating level with or posterior to the origin of the anal fin. Devario anomalus is easily distinguished from D. aequipinnatus by its shorter P-stripe (P-stripe originating on lateral body surface posterior to dorsal-fin origin, vs. P-stripe originating on lateral body surface anterior to dorsal-fin origin) and by its interrupted P- 1 stripe (P- 1 stripe represented by a series of faint blotches along its entire length, vs. P- 1 stripe continuous or interrupted along anteriormost portion only). Devario anomalus is distinguished from D. devario by the presence (vs. absence) of maxillary barbels, the presence (vs. absence) of an infraorbital process on IO 1, and by its lower number of lateral-line scales (33 – 35 vs. 44 – 46), branched dorsal-fin rays (12 vs. 16 – 17), branched anal-fin rays (14 vs. 16 – 17), and circumpeduncular scale rows (12 vs. 16).

Devario anomalus, a new species of freshwater fish from Bangladesh (Ostariophysi: Cyprinidae)

discussion

Remarks. In her morphological phylogenetic analysis of the interrelationships of danionin cyprinids, Fang (2003) restricted the generic name Danio to those danionins in possession of an “ A ” - stripe (a dark stripe extending along the middle of the anal-fin rays and ending at the distal tip of the last branched anal-fin rays) and two or more stripes on the caudal-fin rays. The remaining species of Danio were referred to the genus Devario, a monophyletic group supported by a suite of characters (Fang, 2003: fig. 1) including the following: (1) maxillary barbels shorter than orbit diameter (Fang’s character 2: state 1), (2) a P-stripe extending onto the caudal-fin base (character 14: 1), and (3) infraorbital 5 not or only slightly reduced (character 18: 1). The new species, Devario anomalus, can be assigned to the genus Devario (sensu Fang, 2003) by the presence of short maxillary barbels (much shorter in length than the diameter of the orbit), a P-stripe extending to the caudal-fin base, and an IO 5 similar in width to that of IO 4 (Fig. 5), an assignment that finds support in the results of our molecular phylogenetic analysis (Fig. 6). Rahman (1989) reported two species of Devario

Devario anomalus, a new species of freshwater fish from Bangladesh (Ostariophysi: Cyprinidae)

distribution

Distribution and habitat. Devario anomalus is known only from the type locality (Fig. 3), a small coastal stream originating in the hill tracts south of Cox’s Bazar, southern Chittagong Division. The new species was collected from a small pool at the base of a waterfall (Fig. 4) and from a short stretch of stream downstream of the waterfall and upstream of the highway crossing. Other fish species collected at the type locality include Puntius ticto and an unidentified species of gerreid.

Devario anomalus, a new species of freshwater fish from Bangladesh (Ostariophysi: Cyprinidae)