Pseudoplatystoma Bleeker, 1862

Uriel Angel Buitrago-Suárez & Brooks M. Burr, 2007, Taxonomy of the catfish genus Pseudoplatystoma Bleeker (Siluriformes: Pimelodidae) with recognition of eight species., Zootaxa 1512, pp. 1-38 : 3-8

Pseudoplatystoma Bleeker, 1862

Pseudoplatystoma Bleeker, 1862 :10. Type species: Silurus fasciatus Linnaeus, 1766 . Type by original designation. Gender: neuter. Lundberg and Littmann (2003) stated that Pseudoplatystoma is a valid name by first reviser action of Eigenmann and Eigenmann (1888).

Hemiplatystoma Bleeker, 1862 :10. Type species: Platystoma tigrinum Valenciennes, 1840 . Type by original designation. Gender: neuter.

The etymology of Pseudoplatystoma is as follows: pseudes, (Greek) for false, platys (Greek), flat and stoma (Greek), mouth.

Bleeker used a combination of characters to diagnose his new genus as follows (words in parentheses are ours)

"Snout strongly depressed. Superior maxilla non -prominent. Intermaxillary (premaxillary) teeth minute, vomero -palatine teeth in four patches. Eyes in dorsal position. Nares anterior and tubulated. Long barbels. Spine (pectoral?) serrated, dorsal (spine?) slender. Anal fin short”.

Other features noted in the literature (e.g., Ringuelet et al., 1967; Dahl, 1971; Mees, 1974) include: flat head with occipital region covered by thin skin; posterior occipital process contacting predorsal plate; fontanel of skull extends from middle of snout to posterior line of eyes, at this point it becomes a groove that reaches the occipital; pectoral fins have one spine and 8 rays; anal fin has one spine and 9 rays; caudal fin is forked with branched rays; branchiostegal rays 14-15. We reevaluated these features.

We found six unique characters to support the monophyly of Pseudoplatystoma : foramen formed by the epioccipital process and pterotic (Fig. 2); the articular has a flange or platform on its proximal lateral side (Fig. 3C); the articular presents a large fossa where a novel muscle originates (see Buitrago - Suárez, 2006 and Fig. 3A); the entopterygoid forms a straight angle (Figs. 4A and B); presence of a foramen between the parhypural and hypural at the joint with the compound centrum (Fig. 5); swim bladder expanded anteriorly with one appendicle departing from the anterolateral region on each side (Fig. 6A -C); spotted caudal fin (Figs. 13 and 14).

As recognized here, the genus contains at least 8 species: P. fasciatum restricted to the Guyana region; P. punctifer (formerly recognized as P. fasciatum from the Amazon River); P. orinocoense , n. sp., (formerly P. fasciatum from the Orinoco basin); P. magdaleniatum , n. sp., (formerly P. fasciatum from the Magdalena River); P. reticulatum (formerly P. fasciatum from the Amazon and Paraná rivers); P. corruscans (from the Paraná and São Francisco rivers), P. tigrinum , restricted to the Amazon basin, and P. metaense , n. sp. (formerly P. tigrinum from the Orinoco River).

Additionally, we recognize two clades of Pseudoplatystoma (see Buitrago-Suárez, 2005), both supported by anatomical characters. In the P. fasciatum clade ( P. fasciatum , P. punctifer , P. orinocoense , P. magdaleniatum , P. reticulatum , and P. corruscans ) the anterior fontanel is almost entirely surrounded by the mesethmoid and frontals. The fontanel is surrounded by the mesethmoid, frontal, and supraoccipital in the P. tigrinum clade ( P. metaense and P. tigrinum only) (Figs. 7 and 8). A tooth patch covers the dorsal surface of ceratobranchial5 and extends beyond 1/3 of the ventral region in the P. fasciatum clade. The tooth patch on ceratobranchial5 covers only the dorsal surface in the P. tigrinum clade (Fig. 9). In the P. tigrinum clade, the lateral ethmoid bears a small process anteriorly (Fig. 8). The process develops from a ventral elevation that serves as the site for a connection of a bundle of ligaments coming from the entopterygoid. The P. fasciatum clade lacks this process.

The presence of a median crest in the posterior process of the supraoccipital is uncommon in pimelodines. This feature does not distinguish unambiguously between the two clades, but is present in P. tigrinum , P. metaense and P. magdaleniatum (Fig. 7).