Gymnotus panamensis, James S. Albert & William G. R. Crampton, 2003

James S. Albert & William G. R. Crampton, 2003, Seven new species of the Neotropical electric fish Gymnotus (Teleostei, Gymnotiformes) with a redescription of G. carapo (Linnaeus)., Zootaxa 287, pp. 1-54 : 43-46

Gymnotus panamensis n. sp. Albert and Crampton

(Fig. 11; Tables 2 and 3)

Holotype: CAS 72209, 236 mm, collected 25 February, 1923 in a small creek into the Río Cricamola, nr. Konkitu, Bocas del Toro Province, Panama (08°59'N, 81°55'W) by E. Behre and J. Chambers.

Paratype: CAS 217109, 221 mm, collected with holotype.

Diagnosis: Gymnotus panamensis can be distinguished from all congeners by a unique color pattern in which the dark pigment bands on the anterior 2/3 of body are mottled and blotched with numerous, small (1-2 scales wide), irregularly-formed cream-colored patches, such that the pattern of alternating pale and dark bands is highly obscured. Gymnotus panamensis further differs from other members of the G. pantherinus species-group except G. anguillaris by: 1, restriction of pigment bands to ventral portion of body (rarely extending above lateral line) on anterior half of body; 2, a broader head (mean HW 70% HL vs. mean 53-65%); and 3, a wider mouth (mean MW 46% HL vs. mean 32-43%).

Gymnotus panamensis is most similar to G. anguillaris from which it can be distinguished by: 1, more narrowly set eyes (IO 37-41% HL [mean 39%, n=2] vs. 43-56% [mean 46%, n=8]); 2, a deeper head (HD 68-71% HL [mean 69%,, n=2] vs. 61-68% [mean 64%, n=8]); 3, shorter pre-anal distance (PA 83-89% HL [mean 86%, n=2] vs. 84-122% [mean 99%, n=8]; 4, fewer pored posterior lateral line scales (88-92 [mean 90, n=2] vs. 102-130 [mean 124, n=8]).

Description. Figure 11 illustrates head and body shape and pigment patterns. Morphometric data in Table 2 and meristic data in Table 3. Size up to 236 mm. Size at reproductive maturity and sexual dimorphism unknown. Circular scales present on entire postcranial portion of body from nape to caudal appendage. Gape size in mature specimens large, extending to or beyond posterior nares. Mouth position superior, rictus decurved. Eye position lateral, lower margin of eye dorsal to horizontal with rictus. Anterior narial pore partially or entirely included within gape. Circumorbital series ovoid. Caudal appendage long, more than 0.5 time pectoral-fin length in undamaged and unregenerated specimens. Single hypaxial electric organ, extending along entire ventral margin of body. Electric organ discharge unknown.

Many osteological features not known due to unavailability of specimens for clearing and staining; some character states were determined from radiographs. Dorsoposterior laterosensory ramus of preopercle with single superficial pore. Cranial fontanels closed in juveniles and adults. Anterior margin of frontal straight, continuous with margins of adjacent roofing bones. Frontal postorbital process narrow, less than two times width of supraorbital canal. Frontal broad, its width at fourth infraorbital subequal to that of parietal. Pectoral fin of moderate size, with 14-16 rays. Postcleithrum thin, discoid or sickleshaped. Rib 5 broad, with a large medial triangular shelf. Hemal spines present. Displaced hemal spines absent. Multiple anal-fin ray branching posterior to rays 10-17. Lateral line dorsal rami absent in adults. Length anal-fin pterygiophores equal to or longer than hemal spines.

Color in alcohol. Ground color of body pale brown, with 23 or 24 (n=2) pale-yellow bands on lateral body surface extending from tip of tail to pectoral-fin base. Band appearance obscured by wavy margins and numerous pale patches within dark bands, body surface with a mottled or blotched appearance. Anterior 80% of mid-dorsum without banding. Three bands from either side meet on ventral midline, between anus and anal-fin origin. Two of three bands posterior to last anal-fin ray.

Head not banded, its ground color light brown dorsally grading to pale yellow ventrally, with blotches on cheeks and numerous speckles distributed over branchiostegal membranes and ventral surface of head. Pectoral-fin rays brown or gray, interradial membranes hyaline. Anal-fin rays light brown, anal-fin membrane hyaline.

Distribution. Known only from the type locality in the Río Cricamola on the Atlantic slope of western Panama (Fig. 12). Collected by E. Bermingham and A. Martin in the Río Cricamola in 1993 and 2000 (E.B. pers. comm., specimens not preserved).

Common name. Unknown

Etymology. The specific epithet is named for the country of Panama. An adjective.