Review of Butis (Teleostei: Butidae) from Indo-Pacific islands with description of three new species Author Keith, Philippe Author Mennesson, Marion I. text Cybium 2023 47 4 431 466 http://dx.doi.org/10.26028/cybium/2023-034 journal article 10.26028/cybium/2023-034 2101-0315 12713757 Prionobutis wardi Whitley, 1939 Material examined CAS-SU 4995, holotype (unique) of Prionobutis serrifrons, Rutter, 1897 , male ( 58.3 mm SL), China , Swatow [Shantou]. AMS IA.7849, holotype (unique) of Prionobutis wardi , Whitley, 1939 , male ( 38.8 mm SL), Australia , Northern Territory , off Point Charles near Darwin, June 1938 . RMNH 1997, 3 males ( 59-65 mm SL), China , Amoy, Schliegel coll. SMF 1450, male ( 26 mm SL), Indonesia , Moluccas , Kololobo, 21 May 1908 . BMNH 1894.1.19.35, female ( 56 mm SL), Malaysia , Borneo. NSMT-P 70613, 1 spm ( 40.8 mm SL), Vietnam , Nha Trang market, 7 Oct. 2004 , Shibukawa coll. NSMT-P 70655, 2 spms ( 33.6-60.2 mm SL), Vietnam , Nha Trang market, 7 Oct. 2004 , Shibukawa coll. NB : According to Fricke et al . (2022) , syntypes of Eleotris koilomatodon Bleeker, 1849 (Madura Straits near Surabaya and Kammal, Java , Indonesia ) are in RMNH 4818 (some of 11). According to Kottelat (2013) the holotype ? [ 80 mm TL] is part of RMNH 4818. We went twice in RMNH but failed to locate RMNH 4818. It must be actively sought. Diagnosis Interorbital space without scales with IOS 0/0/0 ( Fig. 1a 6 ); jaws reaching back to middle of eye ( Fig. 1b 4 ); no auxiliary scales on the body ( Fig. 1c 4 ); pectoral fin rays 21-22; body depth at anal fin origin is 21-26% SL; interorbital width 6-8% SL; snout length 7-10% SL. Description The scale counts are given in Table III and selected morphometrics in Table IV. The body is oval and higher than it is elongated, short deep; the body depth at anal fin origin is 21-26% SL, at first dorsal fin 21-28% SL, and the caudal peduncle depth is 9-12% SL. Predorsal length 38-44% SL and preanal length 61-64% SL. Strongly serrated bony ridges on the head (20-30 strong spines) and snout (8-9 spines). Size: up to 85 mm SL. Twenty-five vertebrae. The head 32-35% SL is short and deep; snout length 7-10% SL. Mouth terminal, lower jaw prominent, jaws (13- 15% SL) reaching back to middle of eye ( Fig. 1b 4 ). Teeth small, pointed, in 3-6 rows in each jaw. Interorbital width 6-8% SL. Gill opening to below rear edge of eye. Dorsal fins usually VI-I,8. Large males may have an elongate first (and second) segmented ray in the second dorsal fin. First dorsal fin rounded to blunt. Anal fin usually I,8 directly opposite to the second dorsal fin. Pectoral fins usually 21-22 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 26-29, with ctenoid scales on flanks, opercle, cheeks and caudal peduncle. Scales in transverse back series 9-11, in transverse forward 13-14, in predorsal 12-16 and in zigzag usually 6-7. No scales on snout and on the head between orbital ridge and eyes, IOS 0/0/0 ( Fig. 1a 6 ). Pectoral base, belly and breast scales cycloid. Scales on cheek (SCH) 0-5. No auxiliary scales on body ( Fig. 1c 4 ). Head pores present, with usually incomplete sensory canal and pores (A’, B, C, D, E, F, G, H, I, K, L’), J generally missing; 5 preopercular pores (M’, N, O, P, Q’). Males with a rounded/elongated urogenital papilla with distal tip rounded. Females have a rectangular or chalice-shaped bulbous urogenital papilla with crenulated outer edges around distal opening. Colour in preservation Male and female similar ( Fig. 8A ). Head, pectoral base and opercle beige. Back, flanks and belly brownish. Pectoral and pelvic fins translucent; pectoral fin base with a black spot on the lower part and two basal white spots in front to the black one. Anal and second dorsal fins whitish. Caudal fin whitish to yellowish. Figure 8. – A : Butis koilomatodon, BMNH 1894.1.19.35 (female, 56 mm SL), Malaysia (Photo L. Goodayle, BMNH); B : Butis koilomatodon, Timaka River , Papua New Guinea (Photo G. Allen). Colour in life Male and female similar but the coloration can vary according to the substrate ( Fig. 8B ). Body grey to brownish with about 5 to 6 oblique dark bands (bands may be split at mid-body) from opercle to hypural base. Belly and abdomen yellowish. Head light brown mottled with dark brown, and one white bar from eye to mouth opening. Eyes gold. Lips with alternating white and dark bands. Base of caudal fin black with a row of about 5 yellowish spots. Black spot on the pectoral base surrounded by two white or orange spots in the front and a row of yellowish spot at the base of each ray. First dorsal fin blackish with transparent patches at the rear of fin. Second dorsal fin translucent with alternating black and gold spots from base to mid-fin. Anal fin grey with a distal black band. According to Miller et al . (1989) , “ body with general reticulation, with 2-3 longitudinal series of small dark dots involving many scales above lateral midline; broad dark banding from each dorsal fin base obliquely rearwards towards ventral midline, bifurcating on flank into separate bands; … Head with lateral preorbital and cheek dark bars, confluent under eye; behind eye, dark spot and pale horizontal band to rear opercle; snout mottled ”. Ecology This species is a benthic and sedentary fish well adapted to the water temperature variations ranging from 26 to 36°C, and salinities ranging from 3.8‰ to 37‰ ( Miller et al., 1989 ; Dinh et al., 2020 ). It spawns throughout the year. The length at first maturation of males ( 5.1-8.6 cm TL) is higher than that of females ( 4.8-6.7 cm ), and the fecundity ranges from 3,085 to 32,087 eggs/female ( Dinh et al., 2021 ). This species has high commercial and nutritional values in Vietnam ( Dinh et al., 2020 ). Distribution From Thailand , Vietnam , China , Indonesia , Papua New Guinea and northern Australia ( Fig. 3B ). Comparison Butis koilomatodon differs from the other species sequenced in having a significant percentage of divergence in COI gene (6.2-17.6%) (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, snout length 7-10% SL versus 11-16% SL and predorsal scales 12-16 versus 25-46. It differs from B. gymnopomus in having jaws reaching back to one third to middle of eye versus jaws reaching back to below front part of eye, pectoral fin rays 21-22 versus 18, and snout length 7-10% SL versus 12-14% SL. It differs from B. delagoensis in having pectoral fin rays 21-22 versus 20-21, interorbital width 6-8% SL versus 5-6% SL and a distribution in the Pacific Ocean versus only in the Indian Ocean from Mozambique to India .