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 : 324-326

Betta rubra Perugia, 1893

( Figs. 1A–D , 2A–C , 3A,B , 4 )

Betta rubra Perugia, 1893: 242 ; Volz, 1905: 127 (part), 1907: 127 (part); Regan, 1910: 781, pl. 77, Fig. 1 ; Witte & Schmidt, 1992: 325; Kottelat et al., 1993: 163, pl. 76; Tan & Ng, 2005a: 58; Tan & Ng, 2005b: 119, Fig. 1a,b (part); Tan, 2008: 5 (part)

Material examined. — West Sumatra Province – MSNG 13019 a, 1 ex., lectotype, 28.6 mm SL ; MSNG 13019 , 4 ex., paralectotypes, 26.9–31.4 mm SL; Siboga; E. Modigliani, 1886 . North Sumatra Province – BMNH 1893.5.29:1, 1 ex., paralectotype, 33.3 mm SL; Lake Toba ; E. Modigliani . Aceh Province – ZRC 53989, 40 ex., 26.5–42.1 mm SL; CMK 23280, 4 ex., 31.8–35.6 mm SL ; Sumatra:

Aceh: Kabupaten Aceh Singkil: remnant peat swamp forest near Gosong Telaga, along road Singkil-Subulussalam , outskirts of Singkil town (12 m asl, pH 5.5); T. Sim et al., 19 Apr.2009 . ZRC 54000, 1 ex., 34.0 mm SL ; Sumatra: southern Aceh, trade material; Ishizu , Feb.2008 .

Diagnosis. — Betta rubra can be distinguished from B. dennisyongi by the following suite of characters: an interrupted black postorbital stripe from posterior of eye to mid-opercle, with a large black bar-like marking on posterior half of opercle not extending to opercle edge (vs. a continuous stripe), leaving a clear cream edge over entire opercle margin (vs. not entire opercel margin); less broad suborbital stripe below eye forming a triangular black mark (2–3 scale rows wide, vs. 4–5); more intense body colouration with smaller interspaces between the black body bars; a greater number of anal-fin rays (mode 27, vs. 25); fewer subdorsal scales (5–5½, vs. 6–7); fewer lateral scales (mode 30, vs. 31); fewer vertebrae (mode 29, vs. 30); shorter dorsal-fin base length (11.0–13.4, vs. 13.0–18.4% SL); and larger maximum size (42.1, vs. 35.4 mm SL).

Description. — General appearance as illustrated in Figs. 3A,B , 4 ; meristic and morphometric data of B. rubra are listed in Table 1. Body relatively slender (body depth 25.0– 28.1% SL), head relatively short (head length 30.4–35.7% SL). Dorsal and anal fins pointed, caudal fin rounded with extended median rays and interradial membrane; dorsal fin placed relatively far back (predorsal length 65.4–73.2% SL); anal-fin base length about half of standard length (52.2–58.3% SL); pelvic fin falcate with first ray long and filamentous (30.7–48.9% SL); pectoral fin rounded. Vertebral count: 9–10 + 18–20 = 27–29 (mode = 29, n = 15). Maximum size: 42.1 mm SL.

Preserved colouration. — See Figs. 2A–C , 3A,B for general appearance. Dorsum of body dark brown to black, lateral reddish, ventrum lighter brown to cream. Dorsum of head brown with black spots sometimes indistinct. Lower lip black. Distinct pre- and postorbital dark-brown to black stripes on head, an interrupted postorbital black stripe from posterior of eye to mid-opercle, with a large black almost bar-like marking on posterior half of opercle not extending to opercle edge, leaving a clear cream edge over entire opercular margin. Broad dark brown to black chin-bar/ suborbital stripe present, forming a triangular dark brown to black mark below eye, up to eye diameter in width. Opercle region basal colour brownish to reddish (depending on period of preservation). Male body with irregularly spaced blackish vertical 4–7 bars, restricted to lower half of body; bars prominent on anterior two-thirds of body. Female body dark brownish red, with reddish patches on ventral region. Caudal peduncle spot faint. Fins brownish, sometimes reddish. Dorsal, caudal and anal fins without transverse bars on interradial membrane; with hyaline edge. Pectoral fin hyaline; base black. Pelvic fin reddish.

Live colouration. — See Fig. 4 for general appearance. Basal body colour reddish to brownish. Dorsum darker than ventrum. Dorsum of head with dark brown to black spots.

Mouth with lower lip black. Lower half of iris of eye bright bluish-green. Head and opercle pattern as above; bar-like marking on posterior half of opercle with gold iridescence; opercle edge bright red; rest of opercle region reddish. Body with 4–7 irregularly spaced blackish bars, restricted to lower half of body. Fins reddish. Dorsal, caudal and anal fins with bright bluish-green edge; base of fins with greenish iridescence. Pectoral fin base with an iridescent bluish-green spot. Pelvic fin reddish with greenish flush and green tip.

Field notes. — Betta rubra has not been collected since its original description and no authoritative details of its habitat have ever been published in the scientific literature. The present series of fresh material of this species was obtained from a highly disturbed and fragmented environment. The surrounding peat swamp habitat in the Singkil area had already been cleared, apparently for the planting of oil palm. The surrounding peatlands had been drained by ditches and was hot and dry at the time of the visit in 2009 ( Fig. 5 ). The remnant population of B. rubra was obtained from a pool of stagnant black water next to an uprooted tree. The pool had no other fish in it. The surface was tepid but the deeper portions cool. Other smaller and shallower water pools were sampled but did not contain any fish. A river nearby was also sampled but did not yield any B. rubra .

Distribution. — Betta rubra is currently known definitively

from the peat swamps in the Singkil area in Aceh; possibly Lake Toba (though possibly erroneous; see earlier Introduction) area near Medan in Sumatra Utara; and Sibolga in northern part of Sumatra Barat ( Fig. 6 ).

Remarks. — See discussion in Tan & Ng (2005a, 2005b) for details of a 1982 series (incorrectly referred to as B. rubra ) from MZB which belongs to the new species described herein; and the apparent reddish tinge of the original type series. This species has been recorded to be a paternal oralbrooder by aquarist reports and personal observations.

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.

Fig. 2. Betta rubra: A, MSNG 13019a, lectotype, 28.6 mm SL, left side; B, lectotype, right side, Sibolga; C, BMNH 1893.5.29:1, paralectotype, 33.3 mm SL, Lake Toba.

Fig. 3. Betta rubra: A, ZRC 53989, 34.0 mm SL male; B, ZRC 53989, 37.9 mm SL female; freshly collected specimens from southern Aceh.

Fig. 4. Betta rubra live male specimen from southern Aceh (from same series as ZRC 53989, not preserved).

Fig. 5. Fragmented peat swamp locality in Singkil where a remnant population of B. rubra was collected (2009).

Fig. 6. Map of Sumatra showing distribution of Betta rubra (round symbols) and B. dennisyongi (square symbols).