Fishes that was previously reported as Mystus Scopoli was redefined by Mo (1991), and as a result, most of the large-sized bagrid catfishes that attain standard lengths of up to 800 mm (Ng et al., 2000) have been transferred to the genus Hemibagrus Bleeker. The genus Hemibagrus has been re-diagnosed by Mo (1991) by having a depressed head with a thin, plate-like metopterygoid. This taxon was established by P. Bleeker in 1862 to include species with depressed heads, rugose (ridged or wrinkled) head shields not covered by skin, slender occipital process, and moderately long adipose fins is known from Southeast Asia, Indo-China and southern China (Mo, 1991).
To date, at least five species of Hemibagrus known to Peninsular Malaysia viz. H. gracilis Ng & Ng, H. hoevenii (Bleeker), H. johorensis (Herre), H. nemurus (Valenciennes) and H. wyckii (Bleeker) (see Ferraris, 2007). Previously, Lim & Tan (2002) listed only four species, i.e. H. bleekeri (Volz), H. gracilis, H. hoevenii and H. wyckii.
Several authors reported the presence of H. bleekeri in Peninsular Malaysia (see Ng & Ng, 1995; Lim & Tan, 2002) but as already been noted by Tan & Ng (2000), the type specimen of the fish, i.e. Macrones bleekeri Volz 1903, however, is a primary junior homonym of Macrones bleekeri Day, 1877, a species belonging to Mystus s. str. Thus, the species previously known as “Hemibagrus bleekeri” in Peninsular Malaysia could be referred to H. johorensis or the more widely known species, H. nemurus.
Hemibagrus johorensis (Herre, 1940)
Type: Mystus johorensis Herre, 1940. Type locality: Sungai Kayu, 16 miles north of Kota Tinggi, Johor, Malaysia. Holotype: SU 33026.
Distribution: Peninsular Malaysia and Sumatra.
Hemibagrus nemurus (Valenciennes, in Cuvier and Valenciennes, 1840)
Type: Bagrus nemurus Valenciennes, in Cuvier & Valenciennes, 1840. Type locality: Java. Holotype: Possibly RMNH 269 (not found) or at MNHN.
Type: Mystus pahangensis Herre, 1940: 14, pl. 9. Type locality: Sungai Garam, near Karak, Pahang, Malaysia. Holotype: SU 33025.
Distribution: Java and likely in river basins of neighbouring regions.
Remarks: Ferraris (2007) noted that the name of “Hemibagrus nemurus” has been applied to populations that have been subsequently determined to belong to distinct species. Dodson et al. (1995) studied the mitochondrial DNA of this species but phylogeographic structure was still unstable. The geographic limits of Hemibagrus nemurus still have not been clearly stated (Ferraris, 2007).
Supplementary. Notes on the genus Mystus Scopoli
Members of the genus Mystus are small- to medium-sized catfishes inhabiting streams, lakes and rivers of southern and southestern Asia, with 32 valid species in the group (Ferraris, 2007). The phylogenetic relationships within the genus also remain poorly understood, although the paraphyly of the group has recently been demonstrated (Hardman, 2005).
Molecular evidence presented by Hardman (2005) indicates that the group is paraphyletic.
Hardman (2005) recovered taxa currently assigned to Mystus in three lineages.
p.s. more to come on Mystus in Peninsular Malaysia
To date, at least five species of Hemibagrus known to Peninsular Malaysia viz. H. gracilis Ng & Ng, H. hoevenii (Bleeker), H. johorensis (Herre), H. nemurus (Valenciennes) and H. wyckii (Bleeker) (see Ferraris, 2007). Previously, Lim & Tan (2002) listed only four species, i.e. H. bleekeri (Volz), H. gracilis, H. hoevenii and H. wyckii.
Several authors reported the presence of H. bleekeri in Peninsular Malaysia (see Ng & Ng, 1995; Lim & Tan, 2002) but as already been noted by Tan & Ng (2000), the type specimen of the fish, i.e. Macrones bleekeri Volz 1903, however, is a primary junior homonym of Macrones bleekeri Day, 1877, a species belonging to Mystus s. str. Thus, the species previously known as “Hemibagrus bleekeri” in Peninsular Malaysia could be referred to H. johorensis or the more widely known species, H. nemurus.
Hemibagrus johorensis (Herre, 1940)
Type: Mystus johorensis Herre, 1940. Type locality: Sungai Kayu, 16 miles north of Kota Tinggi, Johor, Malaysia. Holotype: SU 33026.
Distribution: Peninsular Malaysia and Sumatra.
Hemibagrus nemurus (Valenciennes, in Cuvier and Valenciennes, 1840)
Type: Bagrus nemurus Valenciennes, in Cuvier & Valenciennes, 1840. Type locality: Java. Holotype: Possibly RMNH 269 (not found) or at MNHN.
Type: Mystus pahangensis Herre, 1940: 14, pl. 9. Type locality: Sungai Garam, near Karak, Pahang, Malaysia. Holotype: SU 33025.
Distribution: Java and likely in river basins of neighbouring regions.
Remarks: Ferraris (2007) noted that the name of “Hemibagrus nemurus” has been applied to populations that have been subsequently determined to belong to distinct species. Dodson et al. (1995) studied the mitochondrial DNA of this species but phylogeographic structure was still unstable. The geographic limits of Hemibagrus nemurus still have not been clearly stated (Ferraris, 2007).
Supplementary. Notes on the genus Mystus Scopoli
Members of the genus Mystus are small- to medium-sized catfishes inhabiting streams, lakes and rivers of southern and southestern Asia, with 32 valid species in the group (Ferraris, 2007). The phylogenetic relationships within the genus also remain poorly understood, although the paraphyly of the group has recently been demonstrated (Hardman, 2005).
Molecular evidence presented by Hardman (2005) indicates that the group is paraphyletic.
Hardman (2005) recovered taxa currently assigned to Mystus in three lineages.
p.s. more to come on Mystus in Peninsular Malaysia
p.s.s. I don't have key to ID this fish but you can refer to published materials (some I have!)
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