Butis gymnopomus ( Bleeker, 1853 )
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publication ID |
https://doi.org/ 10.26028/cybium/2023-034 |
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persistent identifier |
https://treatment.plazi.org/id/03EA87D8-2607-0D0E-FED0-FD2DF1FFFA03 |
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treatment provided by |
Felipe |
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scientific name |
Butis gymnopomus ( Bleeker, 1853 ) |
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Butis gymnopomus ( Bleeker, 1853) View in CoL
( Figs 1-3B View Figure 1 View Figure 2 View Figure 3 , 6 View Figure 6 ; Tables III-IV)
According to Fricke et al. (2022), the holotype from Western Sumatra of this species is “whereabouts unknown”. In the species description Bleeker (1853) wrote “ Mijne verzameling bevat reeds meerdere soorten van Eleotris met spitsen platten kop, langen snuit en groote zijschubben, zooals Eleotris melanostigma Blkr. , Eleotris melanopterus Blkr. , Eleotris wolffii Blkr. , Eleotris prismatica Blkr. , Eleotris humeralis CV en de boven beschrevene, welke zich echter gemakklejik van alle boven genoemde laat onderkennen aan hare onbeschubte wangen en snuit en tusschenoogstreek. ” i.e., “My collection already contains several species of Eleotris with a flat, pointed head, long snout and large lateral scales, such as Eleotris melanostigma Blkr. , Eleotris melanopterus Blkr. , Eleotris wolffii Blkr. , Eleotris prismatica Blkr , Eleotris humeralis CV and the species described above, which can easily be distinguished from all of these species by its cheeks, snout and inter-orbital region without scales”. This description is sufficiently clear and no neotype designation is needed. B. gymnopomus is, indeed, the only species with an interorbital space without scales (with IOS 0/0/0) and with a flat pointed head and a long snout (see species key).
Material examined
SMF 9964 About SMF , female (72 mm SL), Indonesia, Sunda, Kabaena , Oct. 1908, Sunda exp. coll . SMF 9965 About SMF , 1 female and 2 males (49-73 mm SL), Indonesia, Celebes, Rumbia , Oct. 1909, Sunda exp. coll . MNHN 1963-0596 About MNHN , male (50 mm SL), Cambodia, Sihanoukville, 1961-1962, d’Aubenton & Fily coll. MNHN 1985-0991 About MNHN , 1 About MNHN spm, Cambodia, Sihanoukville, 1962, d’Aubenton & Fily coll. NSMT-P 71103 , 6 spm, Myanmar, Rakhaine, Gwa , Dec. 2001, Onishi coll. NSMT-P 71104 , 3 spms, Myanmar, Rakhaine, Gwa , Dec. 2001, Onishi coll. NSMT-P 66100 , Thailand, Libong , 9 Mar. 2003, Shibukawa coll.
Diagnosis
Interorbital space without scales with IOS 0/0/0 ( Fig. 1a 1 View Figure 1 ); jaws reaching back to below front part of eye ( Fig. 1b View Figure 1 2 View Figure 2 ); no auxiliary scales on the body ( Fig. 1c View Figure 1 4 View Figure 4 ); no black spot on the pectoral fin base; predorsal scales 12-15.
Description
The scale counts are given in Table III and selected morphometrics in Table IV. The body is elongated, the body depth at anal fin origin is 14-21% SL, at first dorsal fin 16-21% SL, and the caudal peduncle depth is 8-10% SL. Predorsal length 40-44% SL and preanal length 61-64% SL. Bony ridges on head barely serrated to smooth (12-24 medium spines), usually smooth on snout (4-8 smooth spines). Size: up to 115 mm SL. Twenty-five vertebrae.
The head 33-36% SL is depressed as is the snout; snout length 12-14% SL. Mouth terminal, lower jaw prominent, jaws (14-16% SL) reaching back to below front part of eye ( Fig. 1b View Figure 1 2 View Figure 2 ). Outermost row of teeth in each jaw enlarged and widely spaced with strong caniniform teeth. Interorbital width 6-8% SL. Gill opening below rear edge of eye.
Dorsal fins VI-I,8 with no filamentous rays; first dorsal fin triangular. Anal fin I,7-8 directly opposite to the second dorsal fin. Pectoral fins 18 with the posterior margin slightly rounded. The caudal fin is with 12 branched- rays and its posterior margin is rounded. Pelvic fins separate, I,5.
Lateral scales 25-28, with ctenoid scales on flanks, opercle and caudal peduncle. Cheek usually naked. Scales in transverse back series 8-9, in transverse forward 11-14, in predorsal 12-15 and in zigzag usually 6. Interopercle naked or with few scattered scales; no scales between orbital ridge and eyes, IOS 0/0/0 ( Fig. 1a 1 View Figure 1 ). No scales on cheeks. Scales absent from snout. Pectoral base, breast and belly scales cycloid. No auxiliary scales on body ( Fig. 1c View Figure 1 4 View Figure 4 ). Head pores present, with usually incomplete sensory canal and pores (A’, B, C, (D), (E), F, (G), H, I, J, K, L’); 5 preopercular pores (M’, N, O, P, Q’). The pore numbers are asymmetrical in some individuals, with a pore on one side of the head, which is absent on the other side. D, E, G sometimes missing.
Males with an elongated urogenital papilla with distal tip rounded. Females have an oval or chalice-shaped bulbous urogenital papilla with slightly crenulated outer edges around distal opening.
Colour in preservation
Male and female similar. Head, body and belly grey-beige to brown. Head with a distinct double broad dark brown to blackish band on snout. Seven to eight oblique dark bands from head to caudal fin. Pectoral and pelvic fins beige. Abdomen and gular region beige. First dorsal fin brown to blackish. Anal and second dorsal fins dark with spots aligned on rays. Caudal fin brownish to blackish with greyish margin.
Colour in life
Male and female similar ( Fig. 6 View Figure 6 ). Head, body and belly grey-beige to brown or red, with several lines of white spots framing scale rows or constituting several longitudinal white to pink lines. Head with a double broad dark brown to blackish band from snout tip running through eye, and scattered with numerous white spots on snout, preopercle and opercle. Opercle pinkish. Several specimens with seven to eight light- er oblique bands from head to caudal fin. Sometimes a dark band runs along the body and ends at caudal fin base. Lips plain brown; eyes red. First dorsal fin brown to blackish with a beige blotch at posterior part. Second dorsal fin blackish with whitish spots along rays and sometimes with a red basal part. Anal and pelvic fins mostly red with a black and white margin or yellowish to brown with some black and yellow to whitish spotting posteriorly. No black spots nor red spots on pectoral fin base; pectoral fin translucent with a base mottled with brown and blackish. Caudal fin translucent to blackish with fine whitish spots; lower and upper base reddish, lower margin whitish.
Ecology
This species occurs in many coastal streams in brackish to freshwaters over substrates of mud, gravels, sandy-mud or rocky bottom. It is an ambush hunter, feeding mainly on small fish and crustaceans (shrimps ( Atyidae ), prawns ( Palaemonidae )).
Distribution
Known from India, Sri Lanka, Myanmar, Indonesia, Thailand and Vietnam ( Fig. 3B View Figure 3 ).
Comparison
Butis gymnopomus differs from the other species sequenced in having a significant percentage of divergence in COI gene (15.7-17.6%) (Table II). Moreover, it differs from B. audebertae , B. humeralis , B. huberti , B. prismaticus , B. butis , B. amboinensis and B. abdoui in having 0 scales versus 2-11 between the two orbital ridges and predorsal scales 12-15 versus 25-46. It differs from B. koilomatodon and B. delagoensis in having jaws reaching back to below front part of eye versus jaws reaching back to one third to middle of eye, pectoral fin rays 18 versus 20-22, and snout length 12-14% SL (versus 7-10% SL).
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