A New Freshwater Ariid (Otophysi: Siluriformes) from the Río Usumacinta Basin

Potamarius usumacintae, new species, is described based on specimens collected in the Río Usumacinta basin in Guatemala and México. The species is diagnosed from other freshwater ariids distributed in Mesoamerica by the following combination of features: lateral gill rakers on first gill arch 17–20 (mode 19); mesial gill rakers on first two gill arches well developed; accessory tooth patches on palate present; premaxillary tooth band length 2.4–2.9 in its width; snout length 1.4–1.8 in postorbital length; maxillary barbel not extending behind gill membrane; dorsomedian fleshy groove on head absent. A key to identify nine Atlantic slope ariid species from North and Central America is provided.

Resumen

Se describe Potamarius usumacintae, nueva especie, con base en especímenes colectados en la cuenca del río Usumacinta en Guatemala y México. La especie se diagnostica de otros ariidos distribuidos en Mesoamérica por la siguiente combinación de caracteres: 17–20 (moda 19) branquiespinas laterales en el primer arco branquial; branquiespinas mesiales en los dos primeros arcos branquiales bien desarrolladas; placas dentarias accesorias presentes en el paladar; longitud de la banda de premaxilar de dientes 2.4–2.9 en su anchura; longitud del rostro 1.4–1.8 en la longitud postorbital; barbillón maxilar no extendiéndose por detrás de la membrana branquial; surco carnoso dorsomedial en la cabeza ausente. Se provee una clave para la identificación de nueve especies de ariidos distribuidas en la plataforma del Atlántico de Norte y Centro América.

Figure 1

Measurements used for morphometric analysis, as shown on a generalized ariid. See Table 1 for abbreviation definitions.

Figure 2

Tooth patches in roof of mouth of (A–C) Potamarius usumacintae (UMMZ 190074, 473 mm SL; UMMZ 198716, 465 mm SL; AMNH 25241, 324 mm SL; respectively), (D) Ariopsis assimilis (UMMZ 196479, 253 mm SL), (E) A. felis (AUM 7414, 214 mm SL), (F) P. izabalensis (after Hubbs and Miller, 1960), (G) P. nelsoni (USNM 50001, 336 mm SL), (H) Cathorops sp. (FMNH 77783, 222 mm SL), (I) C. aguadulce (AUM 32198, 163 mm SL), and (J) C. melanopus (ANSP 64630, 181 mm SL, photograph by M. H. Sabaj). PM, premaxillary bands; AP, accessory tooth patches; V, vomerine patches.

Figure 3

Potamarius usumacintae, UMMZ 248165, holotype, Guatemala, Petén, Río Usumacinta basin, Río San Pedro (Photograph by H. H. Ng).

Figure 4

Known distribution of Potamarius usumacintae in southern México and northern Guatemala. Holotype and three paratypes (star), other paratypes (filled circle).

Figure 5

Dorsal view of skulls of (A) Potamarius usumacintae (UMMZ 198716, paratype, 465 mm SL) and (B) P. nelsoni (UMMZ 198713, 480 mm SL). F, frontal; LCLE, lateral cornu of lateral ethmoid; LF, lateral fenestra; MNP, middle nuchal plate; PDF, posterior dorsomedian fontanelle; SP, supraoccipital; TF, temporal fossa.

Figure 6

Lateral view of second gill arches of (A) Cathorops melanopus (UMMZ 197336, 188 mm SL) and (B) C. aguadulce (UMMZ 186482, 190 mm SL). GR, gill rakers; FP, fleshy papillae.

Contributor Notes

Section editor: C. J. Ferraris.

(RBR) AUBURN UNIVERSITY, 331 FUNCHESS HALL, AUBURN, ALABAMA 36849; AND (PWW) FISH DIVISION, THE FIELD MUSEUM, 1400 SOUTH LAKE SHORE DRIVE, CHICAGO, ILLINOIS 60605. E-mail: (RBR) betanri@auburn.edu; and (PWW) pwillink@fieldmuseum.org. Send reprint requests to RBR.

Received: 11 Jul 2006

Accepted: 21 May 2007