Seven new species of the Neotropical electric fish Gymnotus (Teleostei, Gymnotiformes) with a redescription of G. carapo (Linnaeus).
Author
James S. Albert
Author
William G. R. Crampton
text
Zootaxa
2003
287
1
54
http://www.zoobank.org/urn:lsid:zoobank.org:pub:19CA5B52-4CA5-45CC-A4C7-B234596A8470
journal article
z00287p001
Monophyly and Species-Groups of
Gymnotus
Gymnotus
is unique among gymnotiform fishes in possessing a superior mouth with a prognathous lower jaw; a thick and fleshy pad of tuberous electroreceptor organs and insulating support tissues overlying the tip of the snout and oral jaws; a pair of dorsally oriented pipe-shaped anterior nares partially or entirely included within the gape; a ventrally curved rictus; a lateral position of the eye on the head, about horizontal with the anterior oral margin; numerous long rami of the posterior lateral line extending ventrally on the caudal portion of the body; and a very long body cavity, with 31-51 precaudal vertebrae (Albert 2001; Albert & Crampton 2001).
Albert & Miller (1995) and Albert (2001) recognize three species-groups within the genus based on color pattern and body proportions, the
G. cylindricus
,
G. pantherinus
, and
G. carapo
species-groups. The species composition and geographical range of these groups are summarized in Table 1. The
G. cylindricus
species-group is represented by two species endemic to the Atlantic and Pacific drainages of Middle America. The
G. pantherinus
species-group is represented by 12 species including those described herein, with distributions from Panama to Paraguay. Members of the
G. pantherinus
species-group can be distinguished from those in the other two species-groups by the possession of: a slender body (adult modal BD 6.1-9.0% TL [except
G. melanopleura
] vs. 9.1-11.7% in all other
Gymnotus
species except
G. henni
n. sp.
and
G. esmeraldas
n. sp.
); proximal portion of fifth rib with broad triangular ridge, more than three times width of sixth rib (vs. narrow ridge, less than three times width of sixth rib); dentary hook at mental symphysis composed of paired ventroposterior oriented processes. The
G. carapo
species-group is endemic to South America and is represented by 12 species, including those described herein, with distributions from the Pacific slope of Colombia to the Pampas of Argentina. Members of the
G. carapo
species-group can be distinguished from those in the other two species-groups by the possession of: a clear or pale patch near the caudal end of the anal fin, most visible in juveniles and subadults (60-150 mm); two (vs. one) laterosensory pores in the dorso-posterior portion of preopercle, in the preopercular-mandibular canal. The classification of
Gymnotus
into three species groups is used as a basis for diagnosing the new species described herein.