Pterygoplichthys Gill, 1858

Pterygoplichthys anisitsi (formerly Liposarcus), Photo by K.S. Cummings

Pterygoplichthys scrophus

Pterygoplichthys gibbiceps (formerly Glyptoperichthys), Photo by M.H. Sabaj

Pterygoplichthys zuliaensis, Phot by K.S. Cummings

Pterygoplichthys etentaculatus, Photo by K.S. Cummings

TAXA LIST



Pterygoplichthys was considered by Weber (1991, 1992) to consist of three genera, Pterygoplichthys, Liposarcus, and Glyptoperichthys; however, Armbruster (1997; submitted) could find no characteristics to uniquely diagnose all three genera and recognizes only Pterygoplichthys.  The following is an excerpt from Armbruster (1997). Included is a key being prepared by myself and Larry Page.


GENUS SYNONYMY

Liposarcus Günther 1864
Glyptoperichthys Weber 1991



SPECIES


Key to the Species of Pterygoplichthys by J.W. Armbruster and L.M. Page

(partially modified from Weber, 1992)

 

1a.

Supraoccipital forming distinct median crest.

2

1a.

Supraoccipital flat or rounded, not forming median crest.

7

 

 

 

2a.

Dorsal fin without spots or vermiculations. Caudal fin dark with much lighter upper spine. Flap between anterior and posterior nares more than 0.6 diameter of orbit. Body without spots, usually with large dorsal saddles.

P. scrophus (Cope 1874)

2b.

Dorsal fin with light or dark spots or vermiculations. Caudal fin without much lighter upper spine. Flap between anterior and posterior nares less than 0.6 diameter of orbit. Body with dark or light spots.

3

 

 

 

3a.

Venter with uncoalesced spots.

4

3b.

Venter with vermiculations..

6

 

 

 

4a.

Venter with large, dark spots

P. gibbiceps (Kner 1854)

4b.

Venter with light spots

5

 

 

 

5a.

Venter with large light spots. Cheek of adult with no or few hypertrophied odontodes.

P. joselimaianus (Weber 1991)

5b.

Venter with small light spots. Cheek of adult strongly armed with hypertrophied odontodes.

P. xinguensis (Weber 1991)

 

 

 

6a.

Weakly developed hypertrophied odontodes on evertible cheek plates; ratio of eye height to diameter of eye 2.9-3.8.

P. lituratus (Kner 1854)

6b.

Well developed hypertrophied odontodes on evertible cheek plates; ratio of eye height to diameter of eye 3.7-4.1.

P. parnaibae (Weber 1991)

 

 

 

7a.

Buccal papilla divided medially and lobulate (Fig. 1a).

P. punctatus G nthenther 1864

7b.

Buccal papilla single, tongue-shaped structure without lobulae (Fig. 1b and c).

8

 

 

 

8a.

Lateral plates with long odontodes directed nearly perpendicular to body.

Pterygoplichthys new species

8b.

Lateral plates with short odontodes directed posteriorly.

9

 

 

 

9a.

Adult without hypertrophied odontodes on evertible cheek plates. Usually 10 to 11 (occasionally 12) dorsal-fin rays. Occurring in the rio Amazonas, r’o Orinoco, and rio Paran‡ drainages.

10

9b.

Adult with hypertrophied odontodes on evertible cheek plates. Usually 12 to 14 (occasionally 11) dorsal-fin rays. Occurring in the rio São Francisco, r’o Magdalena, and lago Maracaibo drainages.

13

 

 

 

10a.

Light spots on dark background. Ventral surface consisting of light and dark vermiculations; light vermiculations wider than dark vermiculations.

P. anisitsi Eigenmann & Kennedy 1903

10b.

Dark spots on light background. Ventral surface with dark spots on light background or with light and dark vermiculations of same width or light narrower than dark.

11

 

 

 

11a.

Dark spots discrete, never coalescing or forming dark chevrons on posterior half of body.

P. multiradiatus (Hancock 1828)

11b.

Dark spots often coalescing to form vermiculations on abdomen and head and chevrons on caudal peduncle.

12

 

 

 

12a.

Spots on abdomen mostly discrete, usually no more than five spots coalescing to form short vermiculations.

P. pardalis (Castelnau 1855)

12b.

Nearly all spots on abdomen coalescing to form vermiculations.

P. disjunctivus (Weber 1991)

 

 

 

13a.

Ratio of HL to SL 2.7-3.0; ratio of dorsal base length to SL 5.9-8.0. Occurring in the rio São Francisco of eastern Brazil.

P. etentaculatus (Spix and Agassiz 1829)

13b.

Ratio of HL to SL 3.0-3.4; ratio of dorsal base length to SL 4.9-5.8. Occurring west of the Andes in the Río Magdalena and Lago Maracaibo drainages.

14

 

 

 

14a.

Ratio of HL to SL 3.0-3.3; 10 branched dorsal-fin rays. R’o Magdalena drainage.

P. undecimalis (Steindachner 1878)

14b.

Ratio of HL to SL 3.3-3.4; 10 or 11 branched dorsal-fin rays. Lago Maracaibo drainage.

P. zuliaensis Weber 1991


DIAGNOSIS

Pterygoplichthys is not diagnosed by any unique characteristic.  Characteristics considered synapomorphic are: a wide anterohyal, a medially placed interohyal, a diminutive interohyal, a tall ridge laterally on the articulating condyle of the quadrate, 8-11 postdorsal vertebrae, a tall tripus (reversed in the P. gibbiceps group), and an increase in the number of dorsal fin rays from seven to usually 10 or more.



DESCRIPTION

Species of Pterygoplichthys are large loricariids that have large dorsal fins with nine or more (usually 10+) dorsal fin rays.  Color pattern is generally dark brown with either darker spots or lighter spots or vermiculations.  Abdomen almost completely covered in small plates.  Tail forked with the lower lobe longer than the upper.  Five rows of plates on the abdomen.  The P. multiradiatus group (Liposarcus sensu Weber, 1991; 1992) lacks evertible elongated cheek odontodes, but can still evert the cheek plates at a right angle to the head (Regan, 1904).  The P. gibbiceps group (Glyptoperichthys sensu Weber, 1991; 1992, excluding P. punctatus) is easily recognized by having a large supraoccipital crest (taken to the extreme in P. scrophus. P. punctatus has well-developed, sharp odontodes forming keels on the lateral plates.  See Weber (1992) for more details.



COMPARISONS

Differs from all hypostomines except Acanthicus, Chaetostoma, Delturus, and Upsilodus in usually having 10+ dorsal fin rays (rarely 9).  Acanthicus differs from most Pterygoplichthys by having keels of large odontodes on the lateral plates.  Pterygoplichthys differs from Delturus and Upsilodus by lacking a postdorsal ridge formed of three or more median, unpaired plates and by a fully plated (vs. naked) abdomen, and from Chaetostoma by having three (occasionally two) plates between the suprapreopercle and the exposed opercle (vs. one), an exposed nuchal plate (vs. covered by plates), an exposed spinelet (vs. covered by skin), and a fully plated abdomen (vs. naked).



ECOLOGY

Most common in sluggish streams, floodplain lakes, and marshes.  Some Pterygoplichthys can live out of water for 30 hours (Val and Almeida-Val, 1993).  Males excavate tunnels into mud banks where eggs are laid (see Burgess, 1989 for review).



DISTRIBUTION

Known from the Orinoco, Amazon, Magdalena, Maracaibo, Paraná, and São Francisco systems.  The holotype of P. multiradiatus is supposedly from the Essequibo drainage of Guyana although Weber (1992) does not plot any localities in the Essequibo drainage.



LITERATURE CITED

Armbruster, J.W. 1997. Phylogenetic relationships of the sucker-mouth armored catfishes (Loricariidae) with particular emphasis on the Ancistrinae, Hypostominae, and Neoplecostominae. Unpubl. Ph.D. dissertation. University of Illinois, Urbana-Champaign. 409 pp.

Armbruster, J.W. Submitted. Phylogenetic relationships of the suckermouth armored catfishes (Loricariidae) with emphasis on the Hypostominae and the Ancistrinae. Proceedings of Academy of Natural Sciences of Philadelphia.

Burgess, W.E., 1989. An atlas of freshwater and marine catfishes, a preliminary survey of the Siluriformes. T.F.H. Publications, Neptune City, New Jersey. 784 pp.

Regan, C.T., 1904. A monograph of the fishes of the family Loricariidae. Transactions of the Zoological Society of London 17:191?350.

Val, A.L. and V.M.F. de Almeida-Val. 1995. Fishes of the Amazon and their environment.  Zoophysiology Vol. 32.  Springer-Verlag, Berlin. 224 pp.

Weber, C., 1991. Nouveaux taxa dans Pterygoplichthys sensu lato (Pisces, Siluriformes, Loricariidae). Revue Suisse de Zoologie 98: 637?643.

Weber, C., 1992. Révision du genre Pterygoplichthys sensu lato (Pisces, Siluriformes, Loricariidae. Revue Francaise díAquariologie Herpétologie, 19:1?36.


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