Research Article |
Corresponding author: Veryl Hasan ( veryl.hasan@fpk.unair.ac.id ) Academic editor: Jan Kotusz
© 2023 Veryl Hasan, Lucas O. Vieira, Josie South, Felipe P. Ottoni.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Hasan V, Vieira LO, South J, Ottoni FP (2023) First record of Mastacembelus notophthalmus (Actinopterygii: Synbranchiformes: Mastacembelidae) for Belitung Island, Indonesia. Acta Ichthyologica et Piscatoria 53: 123-127. https://doi.org/10.3897/aiep.53.105318
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This study was conducted aiming to record for the first time the occurrence of Mastacembelus notophthalmus Roberts, 1989 in Belitung Island (Indonesia), and update the geographic distribution of this species. Although this species is categorized as LC according to the IUCN Red List, it is rarely reported in fish inventories, with few specimens sampled. Moreover, data on the geographic distribution, population size, and other population details of M. notophthalmus are scarce and insufficient to predict possible threats and propose appropriate conservation measures and policies. A single specimen of Mastacembelus was collected using a fish trap on 20 February 2023, in a swamp, located in the middle course of the Lenggang River, Belitung Island, Indonesia. This specimen was identified as M. notophthalmus and this finding constitutes the southernmost record for this species, expanding its geographic range. In addition, the new record site is about 700 km south-east of the nearest locality in Peninsular Malaysia, about 250 km south-east of the nearest locality in Bangka Island, about 600 km south-east of the nearest locality in Sumatra, and about 500 km south-west from the nearest locality in Borneo. Better ecological and biological data concerning distribution, habitat, and stressors is crucial to reassess the conservation status of M. notophthalmus, and possible future conservation measures and policies. Therefore, we emphasize here the urgency for more comprehensive and accurate data to facilitate conservation assessments and management in Indonesia.
distribution extension, freshwaters, life below water, native species, spiny eel
Mastacembelus notophthalmus Roberts, 1989 is a freshwater spiny eel species representing the family Mastacembelidae (see
Mastacembelus notophthalmus is known to occur in the western portion of Peninsular Malaysia (Malaysia) (
This work records for the first time the occurrence of M. notophthalmus in Belitung Island (Indonesia). This record represents the southernmost record for this species, extending its geographical distribution further south, and recording its occurrence on one additional island. In addition, we provide here a detailed and updated map of the geographic distribution of M. notophthalmus.
A single specimen of Mastacembelus notophthalmus (Fig.
The morphological inspection of the specimen followed
Family Mastacembelidae Swainson, 1839
Genus Mastacembelus Scopoli, 1777
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).
The specimen collected in the Lenggang River, Belitung Island (Indonesia), was identified as Mastacembelus notophthalmus (Fig.
Meristic and morphometric characters of Mastacembelus notophthalmus from the Lenggang River, East Belitung District, Belitung Island (presently reported study; AMNH0007), and Malay Peninsula (
Meristic data | Mastacembelus notophthalmus | |
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AMNH0007 |
|
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Dorsal spines | 37 | 37–39 |
Dorsal-fin rays | 81 | 73–86 |
Anal-fin rays | 82 | 69–85 |
Pectoral-fin rays | 26 | 24–26 |
Caudal-fin rays | 18 | 15–18 |
Morphometric data; absolute value | ||
Standard length, (SL) [mm] | 410.5 | 248.0 |
Morphometric data; relative values (in percent of SL) | ||
Head length | 1.48 | — |
Snout length | 0.46 | — |
Predorsal length | 6.69 | — |
Preanal length | 6.57 | — |
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).
The new record of Mastacembelus notophthalmus provided here for Belitung Island, specifically for the Lenggang River, Lenggang Village, Gantung Sub-District, East Belitung District, Belitung Island, Indonesia, is the southernmost record for this species, expanding its geographic distribution. In addition, the new record site is about 700 km south-east of the nearest locality in Peninsular Malaysia, about 250 km south-east of the nearest locality in Bangka Island, about 600 km south-east of the nearest locality in Sumatra, and about 500 km south-west from the nearest locality in Borneo. New records of freshwater fishes are essential contributions to the natural sciences (
It is important to emphasize that, despite being categorized as least concern (LC) according to the IUCN Red List, this species is rarely reported in fish inventories, with few specimens sampled (
Given these needs, and the recent reports documenting a far broader distribution for M. notophthalmus than historically considered (
Data curation: VH. Investigation: VH, LOV, JS, FPO. Methodology: VH, FPO. Resources: VH. Writing – original draft: VH, LOV, JS, FPO. Writing – review and editing: VH, LOV, JS, FPO.
The authors thank Mr Wanda Kusumah, Mr Firman Yusnandar, and Mr Imam Wijaya as our guide, and the Universitas Airlangga, Indonesia, for funding our research (No. 254/UN3/2023). FPO thanks the Conselho Nacional de Desenvolvimento Científico e Tecnológico, Brazil (CNPq; grant 307974/2021–9 to FPO), and the Fundação de Amparo à Pesquisa e ao Desenvolvimento Científico e Tecnológico do Maranhão, Brazil (FAPEMA) for providing the financial and infrastructure support to carry out his scientific research. The authors thank two anonymous reviewers for their useful comments.