Gymnotus carapo orientalis, 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 : 430-431

Gymnotus carapo orientalis New Subspecies

Figure 3 F, Tables 3 and 4

Holotype: MZUSP 30025 237 mm, Brazil Pará, Río Tocantins, Río Itacaiuna , Serra Norte, Serra dos Carajás (05°05’S, 050°22’W).

Paratypes: MZUSP 30025 (6), 165–235 mm, Brazil Pará, Río Tocantins, Río Itacaiuna , Serra Norte, Serra dos Carajás (05°05’S, 050°22’W).

Non-Types: MCZ 45189 (19), 133–210 mm, Brazil Pará, Parauapebas, Ilha de Marajó , Río Tocantins, Río Arari , Cachoeira do Arari (01°01’S, 048°58’W) . MZUSP 30008 (8), 173–253 mm, Brazil Pará, Río Trombetas, Río Itacaiunas, Caldeirão, Igarapé do Pojuca (approx. 00°45’S, 056°13’W) . MZUSP 30025 (7), 165–237 mm, Brazil, Pará, Río Tocantins, Río Itacaiuna , Serra Norte, Serra dos Carajás (05°05’S, 050°22’W) .

Description: Specimens of G. carapo from the eastern Amazon overlap substantially in morphometric and meristic PC-space with specimens from other localities ( Figures 4 , 5 , and 12). Gymnotus carapo orientalis 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): slender body (BD 67.9%–88.4% HL, mean 78.4% vs. 42.7%–106%, mean 85.0% in all other subspecies), slender head (HD 50.8%–60.9% HL, mean 55.2% vs. 44.0%–72.4%, mean 58.7% in all other subspecies), narrow head (HW 53.3%–64.4% HL, mean 56.3% vs. 49.1%–67.7%, mean 59.9% in all other subspecies) and short anal-fin length (AF 69.4%–86.6% TL, mean 75.9% vs. 70.9%–88.0%, mean 80.2% in all other subspecies).

Distribution: Known from the eastern Amazon basin in the Brazilian Pará state of Pará, in Amazon river near Belém and Santarém, and the Tocantins and Trombetas basins ( Figure 2 B).

Etymology: Subspecific epithet derived from the Latin “ orientalis ” meaning “of the East”.

G. carapo G. carapo G. carapo G. carapo G. carapo G. carapo G. carapo

Character australis caatingaensis carapo madeirensis occidentalis orientalis septentrionalis

MLP 11222 AUM 20624 UMMZ 190414 MUSM 12949 UMMZ 230734 MZUSP 30025 UF 80734 Morphom.

341 225.0 260.0 227.0 210.0 237.0 220.0

45.0 27.1 31.5 25.9 27.8 31.7 26.0 % 13.2 12.0 12.1 11.4 13.2 13.4 11.8 % 34.4 37.6 36.1 37.8 33.1 35.0 34.3 % 41.1 43.9 42.8 39.0 36.0 43.7 35.5 % 56.9 65.7 61.9 60.6 61.2 60.9 63.7 % 37.6 37.6 41.7 39.8 36.0 35.6 38.4 % 88.9 84.5 96.9 90.0 86.3 74.1 93.2 % 67.1 64.2 68.8 64.1 61.2 54.3 70.3 /BD 82.7 76.0 71.0 71.2 70.8 73.2 75.4 % 57.8 58.3 61.8 57.1 57.9 52.1 62.9 % 66.2 61.3 63.0 59.5 61.9 53.3 61.3 % 28.7 33.2 32.0 37.9 34.5 36.5 38.8 % 63.6 83.8 88.0 74.9 82.7 89.0 80.0 % 40.0 46.9 12.7 43.4 40.3 44.2 45.2 % 82.7 75.6 86.0 74.9 81.0 79.3 81.8 Meristics

23 23 21 16 21 23 21

269 220 235 220 170 220 245 R 15 16 16 13 16 13 17

10 6 6 6 7 6 7

3 4 4 4 4 3 4

8 8 8 8 9 8 8

36 45 40 49 46 46 53

88 76 95 92 88 75 112

10 19 24 18 20 21 23

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.