Hexanematichthys Bleeker, 1858

Marceniuk, Alexandre Pires, Oliveira, Claudio & Ferraris Jr, Carl J., 2024, A new classification of the family Ariidae (Osteichthyes: Ostariophysi: Siluriformes) based on combined analyses of morphological and molecular data, Zoological Journal of the Linnean Society 200 (2), pp. 426-476 : 458-459

Hexanematichthys Bleeker, 1858

( Figs 1–3 , 24D , 32 )

Type species: Bagrus sondaicus Valenciennes, 1840 .

Diagnosis

Posterior branches of mesethmoid moderately long, delimiting between one-fourth and one-half of length of anterior cranial fontanel (8, 0> 1); posterior branch of lateral ethmoid depressed (13, 0> 1); posterior cranial fontanel absent (26, 1> 0); epiphyseal bar indistinct (28, 0> 1); temporal fossa absent (38, 0> 1); accessory tooth plates small, oval to rounded (60, 2> 1); lateral margins of orbitosphenoid progressively diverging anteriorly (63, 0> 1); autopalatine posterior portion conspicuously compressed (106, 0> 1); articulation of autopalatine with lateral ethmoid mesoposteriorly oriented (110, 0> 1); lateral and mesial portions of premaxilla with different sizes (121, 0> 1); anteroventral portion of opercle subtrapezoidal, very long (127, 1> 0); Müllerian ramus distal third markedly curved (208, 1> 2).

Ambiguous optimization: Exoccipital bony crest perpendicular to vertebral column and ventrolaterally directed (92, 1> 0); 15 or more ribs (213, 0> 1); second dorsal cleithral process posteriorly directed and parallel to posterior process (226, 1> 0).

Included species

Hexanematichthys sagor Hamilton, 1822 .

Habitat and distribution: Brackish and marine waters, South and Southeast Asia ( Fig. 24 ).

Remarks

The total-evidence analysis supports the validity of Hexanematichthys , corroborating the result of a previous molecular study (Betancur-R. 2009) that reveals a strong morphological convergence between Hexanematichthys and Sciades (characters 26, 28, 93, 106, and 110), which had resulted in them having previously been treated as synonyms ( Marceniuk et al. 2012).

Figures

Figure 1. MP analysis.Subfamilies (SF) Galeichthyinae (pink), Bagreinae (bright blue), and Ariinae (dark blue). Tribe (T) Ariini (blue), Cathopsini (orange), Genidentini tribe nov. (brown), and Sciadeini tribe nov. (light green).Subtribe (ST) Ariina (light blue) and Doiichthyina (green). Incertae sedis taxa (IS) (red). Numbers over branches correspond to the bootstrap support.

Figure 2. ML analysis. Subfamilies (SF) Galeichthyinae (pink), Bagreinae (bright blue), and Ariinae (dark blue). Tribe (T) Ariini (blue), Cathopsini (orange), Genidentini tribe nov. (brown), and Sciadeini tribe nov. (light green). Subtribe (ST) Ariina (light blue) and Doiichthyina (green). Incertae sedis taxa (IS) (red). Numbers over branches correspond to the bootstrap support.

Figure 3. BI analysis.Subfamilies (SF) Galeichthyinae (pink), Bagreinae (bright blue), and Ariinae (dark blue). Tribe (T) Ariini (blue), Cathopsini (orange), Genidentini tribe nov. (brown), and Sciadeini tribe nov. (light green).Subtribe (ST) Ariina (light blue) and Doiichthyina (green). Incertae sedis taxa (IS) (red). Numbers over branches correspond to the bootstrap support.

Figure 24. Representative skulls, in dorsal view, and distribution of the subtribe Ariina.A, Arius maculatus, AUM 44875. B, Cephalocassis melanochir, CAS 49426. C, Cryptarius truncatus, AUM 50243. D, Hexanematichthys sagor, AUM 50242. E, Kyataphisa nenga, AUM 46280. F, Osteogeneiosus militaris, AUM 44880. G, Pseudosciades sona, AUM 44861. * marine, ** brackish water, *** freshwater.

Figure 32. Hexanematichthys sagor (senior synonym of Bagrus sondaicus), Indo-West Pacific, photograph by Ricardo Betancur-R., type species of the genus.