Mastacembelus notophthalmus Roberts, 1989

Hasan, Veryl, Vieira, Lucas O., South, Josie & Ottoni, Felipe P., 2023, First record of Mastacembelus notophthalmus (Actinopterygii: Synbranchiformes: Mastacembelidae) for Belitung Island, Indonesia, Acta Ichthyologica et Piscatoria 53, pp. 123-127 : 123

Mastacembelus notophthalmus Roberts, 1989

(Fig. 1

New records.

Belitung Island, East Belitung District, Indonesia; middle course of the Lenggang River; 02°57′14″S, 108°09′21″E; 20 February 2023; W. Kusumah leg.; caught with a fish trap; 1 ♂ (ANMH0007).

Identification.

The specimen collected in the Lenggang River, Belitung Island (Indonesia), was identified as Mastacembelus notophthalmus (Fig. 1 ) based on characters proposed by Roberts (1989). The diagnostic features exhibited by the specimen include: (1) a dark vertical bar below eye; (2) dorsal region mostly dark brown with some yellowish irregular vermiculated marks; (3) ventral region yellowish with incomplete and inconspicuous dark brown horizontal stripe; and (4) caudal, dorsal, and anal fins yellowish with vertical dark brown bars (see Fig. 1 ). Meristic and morphometric characters of the M. notophthalmus specimen from Belitung Island are presented in Table 1 . These meristic features also support the identification of the species as M. notophthalmus .

The specimen identified in the presently reported study as M. notophthalmus differs from other species of the genus Mastacembelus occurring in Indonesia and surroundings by the following features: the presence of a dark vertical bar below the eye (vs. absence in Mastacembelus unicolor Cuvier, 1832; Mastacembelus erythrotaenia Bleeker, 1850; and Mastacembelus favus Hora, 1923); number of dorsal spines (37) (vs. 34-35 in M. unicolor , 33-34 in M. erythrotaenia , and 33-35 in M. favus ); number of dorsal-fin rays (81) (vs. 68-70 in M. erythrotaenia ); number of anal-fin rays 82 (vs. 68-69 in M. erythrotaenia ); number of pectoral-fin rays 26 (vs. 24-25 in M. erythrotaenia ); and number of caudal-fin rays (18) (vs. 19-22 in M. unicolor , 14-15 in M. erythrotaenia , and 12-15 in M. favus ).

Figures

Figure 1. Live specimen of Mastacembelus notophthalmus from the Lenggang River, East Belitung District, Belitung Island, Indonesia, 410.5 mm SL (AMNH 0007) (photograph: W. Kusumah).