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Tiger shovelnose genus split into eight species

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Tiger shovelnose genus split into eight species

Post by Admin on Sun May 25, 2008 6:03 pm

Tiger shovelnose genus split into eight species



Pseudoplatystoma corruscans by Neil Hepworth
A revision of the South American tiger shovelnose catfish genus Pseudoplatystoma recognizes eight valid species.

In the revision, which is published inthe most recent issue of the journal Zootaxa, Uriel Buitrago-Suárez and Brooks Burr recognize eight valid species of Pseudoplatystoma, of which three are described as new: P. corruscans, P. fasciatum, P. magdaleniatum, P. metaense, P. orinocoense, P. punctifer, P. reticulatum, and P. tigrinum.

The authors examined a large number of specimens from throughout South America and revalidated two species (P. punctifer and P. reticulatum) in addition to describing three new species (P. magdaleniatum, P. metaense and P. orinocoense). The eight species are distinguished from each other by colour pattern and differences in bone structure.

The exact number of species out of these eight imported for the aquarium trade is unknown since the large majority of the fish imported for the trade are very young fish that are difficult to identify with certainty. According to the authors: “...slight pattern and shape differences may indicate that more than one species is imported.”

Pseudoplatystoma corruscans
Pseudoplatystoma corruscans is known from the Paraná and São Francisco rivers in Argentina, Brazil, Paraguay and Uruguay.

It is distinguished from congeners in having the sides of the body covered with large spots distributed regularly in six to eight rows and four to thirteen pale vertical bars.

Other distinguishing characters include: adipose fin with 5–10 or no spots, caudal fin with few spots, 44–47 vertebrae and surrounding region of both dorsal and ventral procurrent caudal rays with no spots.

The maximum recorded size of this species is 1140 mm TL.

Pseudoplatystoma fasciatum
Pseudoplatystoma fasciatum is restricted to the Guyana region (Essequibo, Rupununi and Suriname river drainages).

The following combination of characters distinguishes it from congeners: “...42–44 vertebrae versus 37–40 in the most similar species, P. punctifer...vertebral complex supporting Weberian apparatus longer than wide; skull at least 1/6 narrower than in other species; usually 10–11 dark vertical bars, relatively wider than similar species from Amazon River; white vertical bars fewer than black vertical ones; generally, darker dorsally than congeners; pectoral and pelvic fins darker with few or no spots; bars posterior to head and opercle relatively more loop–like than straight; first spinelet of anal fin contacts haemal arch of 24th vertebra; conversely, it contacts haemal arch of 22nd vertebra in P. punctifer from Amazon River; last five vertebral centra shorter than in other species.”

The maximum recorded size of this species is 900 mm TL.


Pseudoplatystoma magdaleniatum
Pseudoplatystoma magdaleniatum is named after the Magdalena River in Colombia, to which this species is endemic.

It is distinguished from congeners in having “...rays on dorsal and ventral lobes of caudal fin with fused branches or not separated as in other species of Pseudoplatystoma; wide, straight, dark vertical bars on sides; no loops on nape and associated areas; dorsal and ventral regions of pectoral fin pale with no spots; dorsal fin with few or no spots (sometimes 5 spots); 43 vertebrae; adipose fin with few large spots (6–7 spots); areas surrounding the procurrent rays of dorsal fin without spots; posterior region of the metapterygoid wider than in other species, forming a depression or notch in the dorsal margin of the suspensorium...”

The maximum recorded size of this species is 1000 mm TL.


Pseudoplatystoma metaense
Pseudoplatystoma metaense is known from the Orinoco River drainage is Colombia and Venezuela.

The species is named after the type locality (the Meta River, a tributary of the Orinoco River) and can be distinguished from congeners in having “...rays on dorsal and ventral lobes of caudal fin with fused branches or not separated as in other species of Pseudoplatystoma; wide, straight, dark vertical bars on sides; no loops on nape and associated areas; dorsal and ventral regions of pectoral fin pale with no spots; dorsal fin with few or no spots (sometimes 5 spots); 43 vertebrae; adipose fin with few large spots (6–7 spots); areas surrounding the procurrent rays of dorsal fin without spots; posterior region of the metapterygoid wider than in other species, forming a depression or notch in the dorsal margin of the suspensorium.”

The maximum recorded size of this species is 528 mm TL.


Pseudoplatystoma orinocoense
Pseudoplatystoma orinocoense is named after the Orinoco River, to which this species is endemic.

The following combination of characters distinguishes it from congeners: “...well defined straight vertical bars along side of body, longer than those of P. fasciatum and P. punctifer; bars connecting to, or extending to, the dorsal region and continuing onto other side of body; vertical bars of anterior region straight and extending below dorsolateral dusky area; usually no spots below lateral line, some individuals with two or three spots; 39–41 vertebrae.”

The maximum recorded size of this species is 490 mm TL.


Pseudoplatystoma punctifer
Pseudoplatystoma punctifer is known from the Amazon River drainage, and is distinguished from congeners in having "...37–40 vertebrae; dark vertical bars straight; vertical bars on one side no connecting across dorsum with bars on the opposite side.

"Free, discrete dark spots present below lateral line; first anal spinelet contacts haemal arch of vertebral centra number 22; adipose fin with fewer spots (6 to Cool than sister species, P. fasciatum (10 to 11)."

The maximum recorded size of this species is 1400 mm TL, and given its distribution and that of P. fasciatum, this is the species most likely misidentified as P. fasciatum in aquarium imports.

Pseudoplatystoma reticulatum
Pseudoplatystoma punctifer is known from the Amazon River drainage and the distinctive colur pattern consisting of loop-like dark bars forming a reticulate pattern easily disnguishes it from congeners.

Other disnguishing characters include: "...42–43 vertebrae; anal fin always with spots; no clear demarcation between dark dorsal and pale ventral regions; lower jaw pointed."

The maximum recorded size of this species is 605 mm TL.

Pseudoplatystoma tigrinum
Pseudoplatystoma tigrinum is yet another species known from the Amazon River drainage.

The colour pattern of loop-like bands on the body extending across the dorsal region, the absence of dark spots on the body and the presence of small spots and some loop-like bands on the adipose fin combine to distinguish this species from congeners.

The maximum recorded size of this species is 1300 mm TL.

The recognition of so much hidden diversity within Pseudoplatystoma has implications for both commercial and ornamental fisheries for the group in South America.

The authors state that "Catch data from the different basins can now be better clarified to include all eight species of Pseudoplatystoma, and will allow for more accurate assessment of fishing impact on all the species."

For more information, see the paper: Buitrago-Suárez, UA and BM Burr (2007) Taxonomy of the catfish genus Pseudoplatystoma Bleeker (Siluriformes: Pimelodidae) with recognition of eight species. Zootaxa 1512, 1–38.

Source: http://www.practicalfishkeeping.co.uk

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