Belobranchus belobranchus

Belobranchus belobranchus (Valenciennes, 1837) Figs 1, 2, 3 A – D, 5 A, 6, Tables 1, 2 English name: Throat-spine Gudgeon Eleotris belobrancha Valenciennes in Cuvier and Valenciennes 1837: 243 (type locality: Manado Island, Sulawesi, Indonesia) Belobranchus quoyi Bleeker, 1856: 300 (type locality: Manado Island, Sulawesi, Indonesia) Belobranchus taeniopterus Bleeker, 1856: 301 (type locality: Boleling, Bali, Indonesia) Material examined. Non-type specimens. 94 specimens, all specimens from Indonesia. Java: • MZB.16307, 84.6 mm SL, male, Cibareno, Pasir Baru, Cisolok, Sukabumi, Jawa Barat, S. Sauri et al., 23 Jun. 2002 • MZB.16328, 63.1 mm SL, female, Cilumajan, Pasir Baru, Cisolok, Sukabumi, Jawa Barat, S. Sauri et al., 24 May 2002 • MZB.26872 [ex BIF.01651], 71.7 mm SL, male, Cibareno, Lebak, Banten, 6°57'48.0"S, 105°23'42.0"E, N. Hubert et al., 10 Dec. 2013 • MZB.26873 [ex BIF.1696], 77.5, female, MZB.26906 [ex BIF 01694], 58.7 mm SL, male, Citiis, Sukabumi, Jawa Barat, 6°56'46.0"S, 106°26'45.6"E, N. Hubert et al., 11 Dec. 2013 • MZB.23934, 33.9 mm SL, male, Purworejo, Jawa Tengah, R. Hadiaty, 10 Sep. 2017. Bali: • MZB.26874 [ex BIF.2385], 74.8 mm SL, male, MZB.26907 [ex BIF.2384], 65.0 mm SL, female, Nbang, Jembrana, Bali, 8°22'01.2"S, 114°45'07.2"E, N. Hubert et al., 15 Apr. 2014. Sulawesi: • MZB.4795, 67.4–106.9 mm SL, 2 specimens, male and female, Watu Songu, Ulubongka, Poso, Sulawesi Tengah, Suyanto, 10 Nov. 1982 • MZB.11665, 70.1–108.6 mm SL, 3, 1 male, 2 females, MZB.11676, Lambuno, Wana Mukti, Mountong, Donggala, Sulawesi Tengah, Agus, 3 May 2002 • MZB.11715, 45.4–52.1 mm SL, 6 specimens, 2 males, 4 females, Haryono and A. Munim, 8 Aug. 2001 • MZB.11731, 66.1–100.2 mm SL, 8 specimens, 2 males, 6 females, Wapo river, Lombongo, Suwawa, Gorontalo, Haryono and A. Munim, 7 Aug. 2001 • MZB.11735, 57.3–65.2 mm SL, 4 specimens, 3 males, 1 female, Tolumolu, Kota Selatan, Sulawesi Utara, 8 Aug. 2001 • MZB.11964, 109.5 mm SL, female, MZB.11975, 113.0 mm SL, female, MZB.12048, 62.3 mm SL, female, Bolaang Mongondow, Sulawesi Utara, Haryono and Hesron, 21–26 May 2002 • MZB.20004, 58.6–77.1 mm SL, 3 specimens, 1 male, 2 females, Masembo, Mekongga, Tinukari, Wawo, Kolaka Utara, Sulawesi Tenggara, Jumaring, 30 Nov. 2010 • MZB.20352, 36.4–115.4 mm SL, 17 specimens, 11 males, 6 females, MZB.20381, 52.9–96.2 mm SL, 9 specimens, 5 males, 4 females, MZB.20391, 78.9 mm SL, female, MZB.20398, 107.0– 129.5 mm SL, 3 specimens, 2 males, 1 female, MZB.20406, 58.5–63.8 mm SL, 3 specimens, 1 male, 2 females, MZB.20415, 51.0– 100.3 mm SL, 3 males, Tinukari, Wawo, Kolaka Utara, Sulawesi Tenggara, R. Hadiaty et al., 28 Jun. – 3 Jul. 2011 • MZB.22703, 84.1 mm SL, male, Bonepuso, Bulagi Selatan, Banggai Kepulauan, S. Sauri, 20 Sep. 2014 • MZB.24579, 101.4 mm SL, male, Marinding, Luwu, Sulawesi Selatan, 3°21'43.5"S, 120°15'54.3"E, seine net, D. Lumbantobing, 12 Aug. 2016. Alor: • MZB.5346, 115.3 mm SL, male, Alor, Nusa Tenggara Timur, Sudarmanu, Apr. 1984. Halmahera: • MZB.18812, 85.3 mm SL, male, MZB.18830, 61.3–79.7 mm SL, 3 males, MZB.21174, 32.8 mm SL, male, MZB.21184, 93.4 mm SL, female, MZB.21209, 71.8–98.4 mm SL, 5 specimens, 1 male, 4 females, MZB.21219, 58.2 mm SL, female, MZB.26661 [ex MZB.18747], 63.3–130.7 mm SL, 7 specimens, 1 male, 6 females, MZB.26662 [ex MZB.18820], 71.8 mm SL, female, Ake Jira, Weda Tengah, R. Hadiaty et al., 4 Feb. 2010 – 16 Jul. 2011. Papua: • MZB.15631, 95.2 mm SL, female, Waigeo, Raja Ampat, Papua, R. Hadiaty et al., 4 Jun. 2007 • MZB.17098, 65.3–97.6 mm SL, 2 males, MZB.17118, 59.7–61.0 mm SL, male and female, MZB.17140, 91.9 mm SL, male, Batanta, Raja Ampat, Papua Barat, R. Hadiaty et al., 30 July – 5 May 2008. Diagnosis. A species of Belobranchus with the following combination of characters: head relatively depressed; interorbital width 4.8–8.0 % (mean 6.0 %) of SL; jaw length 10.3–16.7 % (14.1 %) of SL; caudal-peduncle depth 11.9–15.0 % (13.6 %) of SL; body with 3 dark-brown bands seaparated by pale bands, with many dark horizontal lines (one per scale row) along lateral surface; dorsal and lateral surfaces of head with many small whitish spots; 1 or 2 distinct oblique brown lines extending from eye to posterior edge of operculum (not always visible); first dorsal fin typically uniformly mottled dark brown or with thin yellowish distal edge; largest recorded specimen 130.7 mm SL. Distribution and habitat. Belobranchus belobranchus has been recorded from the South China Sea (Randall and Lim 2000), Indonesia: Java, Bali, Lombok, Flores, Alor, Timor, Buton, Sulawesi, and Halmahera islands, and West Papua (Roberts 1993; Tjakrawidjaja 2002; Larson and Pidgeon 2004; Larson et al. 2007; Keith et al. 2012; Tweedley et al. 2013; Dahruddin et al. 2016; Miesen et al. 2016; this study); the Philippines (Jamandre 2023); Japan (Sakai et al. 2001; Nakabo 2002); Papua New Guinea (Fricke et al. 2014; Amick and Toko 2021) (Fig. 6). Belobranchus belobranchus is an amphidromous species, characterized by migration between freshwater and coastal environments (Keith et al. 2012; Sahami et al. 2019); its habitat predominantly encompasses the lower regions of rivers, typically at altitudes to 5 m, and it has been observed in muddy to clear river systems featuring sandy to rocky or gravel bottoms (Parenti 2021). Like most eleotrids, this fish is carnivorous (Kiruba-Sankar et al. 2018).