Gymnotus carapo septentrionalis, Albert, 2017

Albert, James S., 2017, Revision of the polytypic electric fish Gymnotus carapo (Gymnotiformes, Teleostei), with descriptions of seven subspecies, Zootaxa 4318 (3), pp. 401-438 : 432

Gymnotus carapo septentrionalis New Subspecies

Figure 3 G, Tables 3 and 4

Holotype: UF 80734, 220 mm, Venezuela, Apure, Río Apure, E. dike in UNELLEZ module (09°55’7.26”N, 068°17’56.82”W).

Paratypes: UF 80734 (46), 165–262 mm, Venezuela, Apure, Río Apure, E. dike in UNELLEZ module (09°55’7.26”N, 068°17’56.82”W).

Non-Types: NRM 27717 (1), 235 mm, Colombia, Meta, Río Meta, Río Ocoa , Laguna Santa Clara , ca. 5 km S Villavicencio (04°09’N, 073°39’W) . UF 26178 (39), 134–239 mm, Colombia, Meta, Río Guatiquia-Meta , Caños Negros, ca. 9 km Villavicencio on road to Puerto Porfia (04°09’N, 073°39’W) . UF 33245 (1), 200 mm, Colombia, Meta, Río Meta, Río Guamal , 7 km E. Río Guayuriba, just N. Guamal (03°52’N, 073°45’W) . UF 35402 (3), 148– 178 mm, Venezuela, Guarico, Río Apure , ca. 50 km N San Fernando de Apure (07°54’N, 067°28’W) . UF 37030 (20), 101–176 mm, Venezuela, Apure, Río Apure, Río Guaritico , Hato El Frío (09°03’N, 068°20’W) . UF 77334 (1), 173 mm, Venezuela Apure, Río Apure , Cano Caicara, ca. 30 km SW La Ye (07°40’N, 072°22’W) . UF 78069 (3), 151–190 mm, Venezuela, Apure, Río Apure , 2. 3 km N San Fernando de Apure (07°54’N, 067°28’W) . UMMZ 169080 (5), 46–71 mm, Trinidad & Tobago, Mayaro, Gunupia, Mt. Plaisance Village (10°16’N, 061°00’W) .

Description: Specimens of G. carapo from the Río Orinoco Basin in the northern Neotropics overlap substantially in morphometric and meristic PC-space with specimens from other localities ( Figures 4 , 5 , and 12). Gymnotus carapo septentrionalis is characterized by the following combination of statistically significant (p <0.01) traits when compared to the rest of the species as a whole (see Principal Components Analyses and t-tests): narrow mouth (MW 32.9%–38.7% HL, mean 35.5% vs. 32.2%–49.0%, mean 40.9% in all other subspecies), long interorbital distance (IO 35.1%–42.5% HL, mean 39.2% vs. 31.9%–44.8%, mean 37.1% in all other subspecies), deep body (BD 81.5%–96.2% HL, mean 90.1% vs. 42.7%–106.6%, mean 83.8% in all other subspecies), deep head (HD 58.0%–67.2% HL, mean 62.2% vs. 44.0%–72.4%, mean 57.9% in all other subspecies) and more pectoral-fin rays (P1R 16–17, mode 16 vs 13–17, mode 16 in all other subspecies).

Distribution: Known from the Orinoco basin of Colombia and Venezuela, and the island of Trinidad ( Figure 2 B).

Etymology: Subspecific epithet derived from the Latin word “ septentrionalis ”, meaning “of the North”.

Figures

FIGURE 2. Geographic distribution of Gymnotus carapo. A. Closed circles show 111 localities of specimens used in morphometric analyses, and open circles show 191 other verified G. carapo localities. B. Collection localities color coded by subspecies. Note G. carapo is absent from the interior of the Brazilian shield and the Atlantic coast of Brazil from Ceará to Rio Grande do Sul.

FIGURE 3. Specimens illustrating variation in body shape and color pattern among seven subspecies of Gymnotus carapo A. G. c. australis, MLP 11222, 289 mm, Argentina, Misiones province, Río Iguazú basin, Arroyo Verde (25 ° 40 ’ 15 ” S, 053 ° 56 ’ 00.8 ” W); B. G. c. caatingaensis, AUM 20624, 225 mm. Brazil, Piauí, Río Gurgueia aff. Río Parnaíba (08 ° 32 ’ 24 ” S, 044 ° 25 ’ 48 ” W); C. G. c. carapo, UMMZ 190414, 146 mm. Suriname, Brokopondo, Marshal Kreek, aff. Suriname River (05 ° 14 ’ 24.9 ” N, 055 ° 05 ’ 58.6 ” W); D. G. c. madeirensis, UMSS 0 6964, 178 mm. Brazil, Amazonas, Río Beni (10 ° 51 ’ 44.302 ” S, 066 ° 04 ’ 50.300 ” W); E. G. c. occidentalis, UF 122820, 279 mm. Peru, Loreto, Iquitos (03 ° 43 ’ 51.73 ” S, 073 ° 15 ’ 3.83 ” W); F. G. c. orientalis, MCZ 45189, 165 mm. Brazil, Para, Parauapebas, Río Arari, Ilha de Marajó (01 ° 01 ’ S, 048 ° 58 ’ W); G. G. c. septentrionalis, ROM 83885, 233 mm. Guyana, Essequibo, Río Mazaruni (04 ° 55 ’ 33.208 ” N, 060 ° 36 ’ 53.784 ” W). Scale bars = 10 mm.

FIGURE 4. Landmarks used for geometric morphometric analyses. Fifteen landmarks were recorded for 88 morphologically mature specimens from seven subspecies of G. carapo Landmarks: 1) tip of snout; 2) tip of maxilla; 3) margin of maxilla; 4) external naris; 5) second pore of the supraorbital laterosensory canal; 6) point directly above midline of eye; 7) supraoccipital crest; 8) base of first anal fin ray; 9) anus; 10) seventh pore of the posterior marginal laterosensory canal; 11) anterior margin of eye; 12) posterior margin of eye; 13) top of preopercle; 14) top of opercle; 15) base of most ventral pectoral fin ray.

FIGURE 5. Principal components analysis of linear measurements for 175 specimens from seven subspecies of G. carapo: G. c. australis (AU, n = 25), G. c. caatingaensis (CT, n = 8), G. c. carapo (CA, n = 31), G. c. madeirensis (MD, n = 13), G. c. occidentalis (OC, n = 65), G. c. orientalis (OR, n = 16) and G. c. septentrionalis (SE, n = 15). Head length, head depth, body width and body depth load heavily on PC 1, while pre- and postorbital (PR and PO, respectively) and preanal (PA) lengths load heavily on PC 2. Note the substantial overlap in PC space between subspecies.