Gymnotus refugio, Giora, Julia & Malabarba, Luiz Roberto, 2016

Giora, Julia & Malabarba, Luiz Roberto, 2016, Gymnotus refugio, a new and endangered species of electric fish of the Gymnotus pantherinus species-group from southern Brazil (Gymnotiformes: Gymnotidae), Zootaxa 4066 (5), pp. 581-590 : 583-587

Gymnotus refugio , new species

( Fig. 1 )

Gymnotus aff. pantherinus (non Steindachner, 1908). Malabarba et al. 2013: 95 (photo, brief description, distribution map in the rio Tramandaí drainage).

Gymnotus pantherinus (non Steindachner, 1908). Decreto Estadual No 51.797, 9 September 2014 (EN—Endangered species in the list of threatened species of Rio Grande do Sul State, Brazil). Correa et al. 2015: listed for the arroio Chasqueiro).

Holotype. UFRGS 8752, 1 (171.53 mm TL), Brazil, Rio Grande do Sul State, Amaral Ferrador, creek in the former Ferraria farm, laguna dos Patos drainage (30°50'54"S 52°23'19"W), November 2006, J. Anza & R. Hirano.

Paratypes. Brazil, Rio Grande do Sul State. Laguna dos Patos drainage: MCP 20197, 2 (203.06–213.73 mm TL), Viamão, puddle in the swampy forest located at Refúgio da Vida Silvestre Banhado dos Pachecos (30°05'44"S 50°50'59"W), 22 December 2011, J. P. Miranda, B. Calegari, R. Fonseca & C. Alff. MZUSP 8749, 2 (124.87–156.72 mm TL), collected with the holotype. UFRGS 8749, 2 (136.66mm C&S, and 148.55 mm TL), collected with the holotype. UFRGS 13603, 1 (193.93mm TL), UFRGS 13618, 3 (126.42–160.10 mm TL), Amaral Ferrador, creek in the former Ferraria farm (30°50'46"S 52°23'17"W), 3 November 2010, J. Giora, J. Wingert, J. Ferrer & E. Oliveira. UFRGS 13296, 1 (84.14 mm TL), Turuçu, Corrientes creek (31°29'48"S 52°17'42"W), 17 March 2008, L. E. K. Lanes, A. C. Gonçalves & M. V. Volcan. UFRGS 13328, 1 (68.99), UFRGS 20196, 2 (116.15–167.83 mm TL), Pelotas, Carmelitas creek (31°44'53"S 52°13'27"W), 16 May 2006, A. C. Gonçalves, M. V. Volcan & L. E. K. Lanes. UFRGS 13607, 3 (130.02–187.87 mm TL), Pelotas, Laranjal beach, Carmelitas creek near its mouth in laguna dos Patos (31°44'52"S 52°13'22"W), 3 November 2010, J. Giora, J. Wingert, J. Ferrer & E. Oliveira. UFRGS 13813, 3 (81.48-161.13 mm TL), Viamão, puddle in the swampy forest at Refúgio da Vida Silvestre Banhado dos Pachecos (30°05'43"S 50°50'59"W), 9 November 2010, G. Frainer, S. Leonardi, J. Giora & L. R. Malabarba. UFRGS 16371, 3 (151.19–186.49), Viamão, puddle in the swampy forest located at Refúgio da Vida Silvestre Banhado dos Pachecos (30°05'44"S 50°50'59"W), 13 September 2011, C. Mesquita & V. Caorsi. UFRGS 20197, 2 (190.30–213.73 mm TL), Viamão, puddle in the swampy forest located at Refúgio da Vida Silvestre Banhado dos Pachecos (30°05'44"S 50°50'59"W), 22 December 2011, J. P. Miranda, B. Calegari, R. Fonseca & C. Alff. UFRGS 20198, 2 (227.54–229.70 mm TL), Viamão, puddle in the swampy forest located at Refúgio da Vida Silvestre Banhado dos Pachecos (30°05'44"S 50°50'59"W), 17 August 2011, J. P. Miranda, F. A. S. Santos, C. V. Machado & S. Costa. UFRGS 20199, 2 (202.66–207.21 mm TL), Viamão, puddle in the swampy forest located at Refúgio da Vida Silvestre Banhado dos Pachecos (30°05'44"S 50°50'59"W), 15 July 2011, J. P. Miranda, F. A. S. Santos, E. Senna, C. V. Machado & C. S. Prauchner. Rio Tramandaí drainage: MNRJ 9439, 2 (101.20–116.84 mm TL), Torres, Parque Estadual de Itapeva (29°21'23"S 49°45'57"W), 13 September 2005, F. Mello, R. Setubal & M. de Luz. UFRGS 9439, 2 (80.37–116.84 mm TL), Torres, Parque Estadual de Itapeva (29°21'23"S 49°45'57"W), 13 September 2005, F. Mello, R. Setubal & M. de Luz. UFRGS 19595, 3 (101.85– 216.44 mm TL), Maquiné, Barra do Ouro, road to Garapiá waterfall (29°32'14"S 50°14'45"W), 19 September 2014, L. R. Malabarba, P. C. Silva, U. Santo & A. Langoni. Brazil, Santa Catarina State. Rio Mampituba drainage: UFRGS 10829, 2 (68.47–107.66 mm TL), Praia Grande, creek tributary of the rio Mampituba (29°10'36"S 49°58'14"W), 12 September 2008, A. Thomaz, G. Neves, J. Ferrer & J. Wingert. UFRGS 10873, 1 (128.28 mm TL), Praia Grande, flooded area near rio Mampituba (29°15'10"S 50°07'00"W), 14 September 2008, A. Thomaz, G. Neves, J. Ferrer & J. Wingert.

Diagnosis. Gymnotus refugio differs from other members of the G. pantherinus species-group (except G. capitimaculatus and G. pantherinus ) in possessing a color pattern in life or in alcohol composed of yellow to dark brown ground with thick and/or vermiculated spots near anal-fin base up until the lateral line, some specimens showing very few or absent spots ventral to lateral line, versus body with color pattern composed of light and dark pigments bands ( G. anguillaris , G. capitimaculatus , G. cataniapo , G. coatesi , G. coropinae , G. javari , G. jonasi , G. melanopleura , G. panamensis , G. pantanal , G. pedanopterus , G. stenoleucus ) or broad irregular dark pigment blotches ( G. onca ). The new species further differs from G. pantherinus in possessing a deeper head (55.6–68.1 vs.

48.1–55.05% HL), shorter caudal filament (0.7–3.2 vs. 2.7–5.4% TL) ( Fig. 6 ) and wider mouth gape (31.8–43.9 vs. 27.1–36.1% HL) ( Fig. 7 ) and from G. capitimaculatus in possessing shorter interorbital distance (28.3–38.5 vs. 39.8–43.4% HL), wider mouth gape (31.8–43.9 vs. 26.0–28.3% HL), shorter caudal filament (0.7–3.2 vs. 3.2–5.5% TL), higher number of pectoral-fin rays (16–18 vs. 15), and higher number of pored lateral line scales (80–105 vs. 56–74).

Description. Morphometric and meristic data presented in Table 1 . Lateral head profile conical; dorsal portion flattened towards tip of snout. Mouth superior, lower jaw longer than upper. Mouth large, extending nearly posterior naris. Eyes small and lateral; mean interorbital distance 32.2% of HL. Anterior narial pore within mouth gape in large narial fold. Body slender, slightly compressed laterally, and relatively deep. Dorsal profile slightly convex from snout to supraoccipital, nearly straight posteriorly to caudal filament. Ventral profile gently convex from lower jaw to caudal filament. Highest body depth posterior to anal-fin origin. Body depth increasing smoothly from head to body region near 20th anal-fin ray, nearly same depth to 2/3 of TL, and gradually decreasing from that point to caudal filament. Caudal filament short, slender, and laterally compressed. Moderate cycloid scales covering all trunk. Scales smaller on anterior third portion of body; posterior scales at dorsal and medial body regions nearly two to three times larger in diameter than anterior ones; smallest scales covering region of anal-fin pterygiophores. First anterior perforated scale of lateral line above pectoral fin origin; lateral line extending to caudal filament tip with an intermittent distribution. Absence of urogenital papilla. Pectoral fins rounded with perpendicular insertion; pectoral-fin rays i–ii + 14–17 (16–18 total pectoral-fin rays, n = 36, mode = 17). Anal fin long with iii–vi + 205–244 rays (210–247 total anal-fin rays, n = 27, mode = 229). Anal-fin origin posterior to distal tip of pectoral fin. Precaudal vertebrae 45–47 (n = 2).

n Min Max Mean SD Total length (mm) 10 176.8 246.5 212.2 -

Percents of total length

Head length 10 9.9 11.0 10.5 0.4 Body width 9 5.0 6.7 5.6 0.5 Body depth 10 6.9 10.2 8.3 1.1 Pre-anal distance 9 8.9 10.6 9.8 0.5 Snout to anal aperture 10 7.7 9.8 9.0 0.6 Snout to anal-fin origin 10 17.8 20.3 19.0 0.7 Pre-pectoral distance 10 9.5 10.6 10.1 0.4 Anal-fin length 10 72.8 78.3 77.0 1.6 Caudal filament length 9 2.7 5.4 4.0 0.8

Percents of head length

Posorbital length 13 57.7 63.3 61.5 1.7 Preorbital length 13 23.9 32.7 29.9 2.3 Orbital diameter 13 5.8 7.4 6.4 0.5 Nasal aperture distance 13 13.5 18.8 16.8 1.6 Posterior narine to eye 13 9.8 12.5 11.1 0.9 Head depth 13 48.1 55.0 52.2 1.8 Head width at eye 13 39.2 49.1 44.7 2.7 Interorbital distance 13 28.5 35.8 31.2 2.3 Branchial opening 13 30.2 37.3 33.0 2.3 Head width at operculum 13 50.2 63.9 58.3 4.0 Gape width 13 27.1 36.1 32.6 2.5 Pectoral-fin length 11 32.6 40.6 36.4 2.58 Color in life. Ground color solid dark brown dorsal to lateral line. Ground color light brown to yellowish ventral to lateral line; presence of thick and/or vermiculated dark brown spots, between anal-fin base and lateral line is variable, some specimens showing very few or absent brown spots ventral to lateral line ( Fig. 2 ). Specimens with both color patterns can be found in same lot, and this variation in coloration is not related to sexual dimorphism or ontogeny. Anal and pectoral-fin rays dark brown, with pale hyaline inter-radial membranes.

Color in alcohol. The same pattern described for color in life, except that the specimen may appears more opaque due to the fixation of the mucus covering head and body.

Distribution. Gymnotus refugio is known from coastal rivers of laguna dos Patos, rio Tramandaí, rio Maquiné, and rio Mampituba drainages, occurring from southern Rio Grande do Sul to the southern border of Santa Catarina States, Brazil ( Fig. 3 ).

Habitat. Gymnotus refugio inhabits streams, small tributaries, and puddles with shallow and lentic waters, muddy bottom and dense riparian vegetation. It is specially associated to riparian vegetation known as Mata Paludosa (= swampy forest), living under aquatic vegetation roots or in flooded vegetated margins ( Fig. 4 ). At collecting sites throughout Rio Grande do Sul State, the only gymnotiform species occasionally collected along with G. refugio was Brachypopomus draco Giora, Malabarba & Crampton 2008. Gymnotus refugio is usually a rare fish where it has been collected ( Correa et al. 2015 and personal observation), except in conservation areas of the Rio Grande do Sul State where it seems to be abundant associated with preserved dense riparian vegetation.

Conservation Status. Gymnotus refugio was recently evaluated as EN (Endangered) according to the IUCN criteria in the list of threatened species of fauna of Rio Grande do Sul State, Brazil, but it is named therein as Gymnotus pantherinus (Decreto Estadual No 51.797, 9 setembro de 2014). The classification was based on the low and drastically fragmented distribution of the species associated with its high habitat specificity, and the high susceptibility of this habitat to anthropic alteration.

Etymology. The name “ refugio ”, from the Portuguese meaning “sanctuary”, is in reference to the distribution of the species that was found abundant only in two conservation areas of the Rio Grande do Sul State: “ Refúgio da Vida Silvestre Banhado dos Pachecos (where it was collected monthly for ecological studies)” and “Parque Estadual de Itapeva”.

Figures

FIGURE 1. Gymnotus refugio, holotype (UFRGS 8752, 171.53 mm TL), laguna dos Patos drainage, Amaral Ferrador, Rio Grande do Sul State, Brazil.

FIGURE 2. Color pattern variation in Gymnotus refugio, paratypes, UFRGS 16371 (above, 176.29 mm TL, below, 151.19 mm TL), Refúgio da Vida Silvestre Banhado dos Pachecos, Viamão, Rio Grande do Sul State, Brazil. Photos taken just after fixation in formalin.

FIGURE 3. Distribution of Gymnotus refugio in southern Brazil. Circles represent paratype localities; empty circle represents the type locality.

FIGURE 4. Typical habitat of Gymnotus refugio. Carmelitas creek covered by dense aquatic vegetation near its mouth in laguna dos Patos, Laranjal beach, Pelotas, Rio Grande do Sul State, Brazil.

FIGURE 6. Comparison between linear regressions of caudal filament length versus total length (TL) for Gymnotus pantherinus and G. refugio.

FIGURE 7. Comparison between linear regressions of gape width versus head length (HL) for Gymnotus pantherinus and G. refugio.

Tables

TABLE 1. Morphometric data of the holotype and paratypes of Gymnotus refugio.

	Holotype n	Min	Max	Mean	SD
Total length (mm)	171.5 30	80.4	234.4	157.4	-
Percents of total length
Head length	9.5 30	9.3	12.1	10.5	0.8
Body width	5.6 30	4.6	6.4	5.6	0.5
Body depth	8.2 28	7.4	9.8	8.6	0.5
Pre-anal distance	10.9 29	8.3	11.5	10.0	0.8
Snout to anal aperture	9.0 29	8.7	12.2	10.1	1.0
Snout to anal-fin origin	20.5 30	18.2	23.5	20.7	1.5
Pre-pectoral distance	9.5 30	9.1	12.6	10.4	1.0
Anal-fin length	77.9 30	74.6	79.6	77.2	1.5
Caudal filament length	1.8 25	0.7	3.2	2.1	0.8
Percents of head length
Postorbital length	62.0 40	52.3	63.1	59.4	2.4
Preorbital length	29.1 40	27.5	34.4	30.5	1.7
Orbital diameter	8.0 38	5.9	10.1	7.4	0.7
Nasal aperture distance	19.7 39	15.5	22.9	18.4	1.7
Posterior nare to eye	12.0 38	8.7	12.6	11.0	1.0
Head depth	62.1 39	55.6	68.1	59.4	2.6
Head width at eye	50.9 39	39.5	55.7	47.7	3.8
Interorbital distance	32.9 40	28.3	38.5	32.3	2.3
Branchial opening	39.3 40	30.2	46.0	35.9	3.0
Head width at operculum	65.8 40	55.5	65.9	60.0	2.5
Gape width	42.1 40	31.8	43.9	37.0	3.2
Pectoral-fin length	41.2 40	30.4	46.6	38.4	3.2