Betta rubra, Perugia, 1893

Hui, Tan Heok, 2013, The Identity Of Betta Rubra (Teleostei: Osphronemidae) Revisited, With Description Of A New Species From Sumatra, Indonesia, Raffles Bulletin of Zoology 61 (1), pp. 323-330 : 324

Betta rubra species group

Witte & Schmidt (1992) distinguished B. rubra as having a triangular mark below the eye; found in the lowlands of northwestern Sumatra; and size up to 38 mm SL. From the present study, it is clear that B. rubra is not allied to the B. foerschi group; it deserves its own species group (based on morphology, and molecular data, Rüber, pers. comm.). Betta rubra does not have the twin bars on the opercle as observed in living specimens and fresh material (which is one of the characters for B. foerschi group). Instead, the opercular pattern consist of an interrupted or continuous black postorbital stripe to the edge or near the edge of opercle with the posterior part of the postorbital stripe enlarging to a bar-like marking ( Fig. 1A–D ). Betta rubra is also sexually dimorphic when mature; males being more colourful and having black bars on the body, whereas females are paler or uniform in colour pattern, with a black stripe on the body and with a distinct white roundish genital papilla.

The Betta rubra group can be further defined by the following characters: suborbital stripe below eye always present and broad (2–5 scale rows; equivalent to a triangular mark; Fig. 1 ); anal fin II–IV, 22–25 (total = 25–27); lateral scales 29–32; both males and females with pointed dorsal and anal fins, rounded caudal fin with extended median rays; mature males with 4–8 broad black lateral bars; females and juveniles with longitudinal black lateral stripe; found in lowland habitats of northwestern Sumatra; and size up to 42 mm SL.

Figures

Fig. 1. Comparison of lateral head and opercle pattern, left side with photograph, right side with schematic drawing. A, B, Betta rubra, MSNG 13019, lectotype, 28.6 mm SL; C, D, Betta rubra, ZRC 53989, 34.0 mm SL male; E, F, Betta dennisyongi, MZB 17207, holotype, 27.4 mm SL male.