Betta midas, Tan, Heok Hui, 2009

Tan, Heok Hui, 2009, Redescription of Betta anabatoides Bleeker, and a new species of Betta from West Kalimantan, Borneo (Teleostei: Osphronemidae), Zootaxa 2165, pp. 59-68 : 64-67

Betta midas , new species

( Figs. 4–8 )

Material examined. Holotype. MZB 3846, 58.0 mm SL; West Kalimantan, Kabupaten Pontianak: small stream draining into Sungai Sepatah, a tributary to Sungai Mandor , 24 km NE of Pontianak (0°07.5’N 109°30’E); T. R. Roberts et al., 10 July 1976.

Paratypes (all from West Kalimantan). ZRC 43711, 8 ex., MZB 9334, 2 ex., CMK 20838, 2 ex., 35.7–51.0 mm SL; Kabupaten Pontianak: Sungai Kepayan, blackwater brook at km 58 Pontianak on Pontianak–Anjungan road, ca. 7 km before Kampung Anjungan (00°18.84’N 109°08.09’E); donated by Patrick Yap, 8 July 1998. — ZRC 46191, 4 ex., 49.0– 61.4 mm SL; Kabupaten Pontianak: Anjungan; donated by F. Yuwono, Oct 1999. — CMK 16320, 7 ex., 36.5–51.5 mm SL; Anjungan; don. P. Yap, May 2000. — ZRC 46190, 12 ex., 45.6–58.5 mm SL; Kabupaten Pontianak: Kapuas basin; donated by P. Yap, 3 Mar 2000. — ZRC 51527, 1 ex., 66.0 mm SL; Kapuas basin, Tayan area; H. H. Tan, Aug 2007.

Non-type material ZRC 43712, 4 ex., 35.0– 43.3 mm SL; West Kalimantan, Kabupaten Pontianak: Sungai Kepayan, blackwater brook at km 58 Pontianak on Pontianak–Anjungan road, ca. 7 km before Kampung Anjungan (00°18.84’N 109°08.09’E); donated by Patrick Yap, 8 July 1998. — ZRC 51526, 1 ex., 61.4 mm SL; Sarawak: Lundu, Batang Kayan basin, Sungei Temelan; M. Lo, 28 Aug 2005.

Diagnosis. Betta midas is unique in having the following combination of characters: relatively thick-set body (body depth 24.3–29.0 % SL); head devoid of pattern except for black stripe that runs from black lower lip, through eye to edge of opercle; opercle with gold iridescent scales when live; belly and body with gold iridescent scales; some median caudal rays projecting beyond fin margin.

Description. General appearance as illustrated in Figs. 4–8 . Meristic and morphometric data listed in Table 1. Head blunt, relatively long (HL 31.9–34.4 % SL); body relatively thick-set (body depth 24.3–29.0 % SL); pectoral fin rounded; pelvic fin filamentous; dorsal fin situated far back (predorsal length 65.5–67.4 % SL); dorsal and anal fins pointed with elongated posterior rays; caudal peduncle deep (caudal peduncle depth 16.8–19.0 % SL); caudal fin lanceolate, with some median rays projecting beyond fin margin.

Coloration in life. Refer to Linke (1991: 49) and Kottelat et al. (1993: cover photo) and Figs. 5 and 7 for colour illustration. There appears to be no discernible external characters to differentiate the sexes. Dorsal of body brown, ventral lighter brown speckled with gold iridescent scales. Dorsal of head brown with blotches of darker brown behind eye, opercle with distinct greenish-gold iridescence. Distinct pre- and postorbital black stripes on head, lower lip black, chin-bar absent. Body sometimes with central, lower central dark brown stripes and caudal peduncle spot. Fins brownish, dorsal fin with 5–8 dark brown dorsal transverse bars, anal fin sometimes with dark distal edge, caudal fin with 10–12 brown transverse bars. Pectoral fin yellowish. Pelvic fin with bright whitish distal tip.

Coloration in preservative. See Figs. 4 , 6 and 8 . Dorsal of body dark brown, ventral lighter brown to whitish. Dorsal of head dark brown, opercle area whitish. Distinct pre- and postorbital black stripes on head, chin-bar absent. Body with faint central, lower central stripes and caudal peduncle spot. Fins brownish, dorsal fin with 5–8 dorsal transverse black bars, caudal fin with 10–12 faint transverse bars. Pectoral fin yellowish. Pelvic fin light brown, with hyaline filamentous second ray.

Distribution. Betta midas is currently known from the lower Kapuas basin near the village of Anjungan, about 60 km away from the town of Pontianak towards Mandor , Mandor area and Tayan area; possibly the Sambas river basin; and the extreme western part of Sarawak, in heathforest streams near the town of Lundu ( Fig. 3 ).

Field notes. The paratype series (ZRC 43711) is from a blackwater river (Sungai Kepayan) running through remnant and intact peat swamp forest, with a pH of 4.1. Depth ranged from 20 cm to more than 2 m. Syntopic species include: Osteochilus spilurus , Puntius rhomboocellatus , Rasbora dorsiocellata , R. gracilis , R. pauciperforata , Sundadanio cf. axelrodi ( Cyprinidae ), Kottelatlimia pristes (Cobitidae) , Neohomaloptera johorensis (Balitoridae) , Nanobagrus fuscus (Bagridae) , Kryptopterus macrocephalus , Ompok weberi , Silurichthys phaiosoma (Siluridae) , Hemirhamphodon phaiosoma [often mis-identified as H. kapuasensis , which has a restricted distribution in middle Kapuas] ( Hemiramphidae ), Nandus nebulosus (Nandidae) , Belontia hasseltii , Betta edithae , Luciocephalus pulcher , Parosphromenus anjunganensis , P. ornaticauda , Sphaerichthys osphromenoides (Osphronemidae) .

Etymology. An allusion to the Greek Midas , a mythical king whose touch turned everything to gold, arising from the iridescent gold opercle and body scales. Applied as a noun in apposition.

Remarks. Roberts’ (1989: 172) material from other than the type locality identified as B. anabatoides is in fact another species belonging to the B. akarensis group: this exhibits a chin-bar and has a slimmer body (e.g., MZB 3848).

Betta midas can be differentiated from B. anabatoides by the following characters: a less thick-set body ( Fig. 2 ; body depth 24.3–29.0% SL, vs. 30.5–33.7); a less deep caudal peduncle (16.8–19.0 % SL, vs. 19.8–22.1); the presence of caudal transverse bars (vs. absence); the presenc of distinct iridescent gold opercle scales (vs. faint); the presence of gold body and belly scales (vs. absence); a blunt lateral head profile (vs. pointed); a slightly lesser predorsal length (65.5–67.4 % SL, vs. 66.8–69.7); slightly smaller anal-fin base length (52.4–57.9 % SL, vs. 55.2–61.1).

Figures

FIGURE 2. Betta anabatoides, not preserved, ca. 35 mm SL, Central Kalimantan.

FIGURE 3. Map showing known distribution of B. anabatoides (circle) and B. midas (square) in Borneo.

FIGURE 4. Betta midas, ZRC 46190, 48.3 mm SL, paratype from Sungai Kepayan, West Kalimantan (right side, laterally inverted).

FIGURE 5. Betta midas, not preserved, ca. 35 mm SL, Sungai Kepayan, West Kalimantan.

FIGURE 6. Betta midas, ZRC 51527, 66.0 mm SL, paratype from Tayan.

FIGURE 7. Betta midas, ZRC 51527, 66.0 mm SL, live paratype from Tayan.

FIGURE 8. Betta midas, ZRC 51526, 61.4 mm SL, Sarawak, Lundu.