Distocyclus guchereauae, Meunier & Jégu & Keith, 2014

Meunier, François J., Jégu, Michel & Keith, Philippe, 2014, Distocyclus guchereauae a new species of Neotropical electric fish, (Gymnotiformes: Sternopygidae), from French Guiana, Cybium 38 (3), pp. 223-230 : 224

Distocyclus guchereauae , new species

( Figs 1 , 2 , 3 ; Tabs I, II)

Comparative material

Archolaemus blax , French Guiana: MNHN 2013-1199, 1 spm, 198 mm TL, Approuague, Le Bail coll., 3 Apr. 1983.

Distocyclus conirostris , Venezuela: Eight specimens (data from Mago-Leccia, 1978, tables IV, V). USNM 121597 , holotype, photograph and X-ray .

Distocyclus goajira . USNM 121596 , holotype and USNM 121597 , paratype (data from Mago-Leccia F., 1978, tables VI, VII). USNM 121596 , holotype, X-ray.

Eigenmannia virescens , French Guiana: MNHN 2006- 1785, 8 spms, 93-183 mm TL, Litany river (Maroni), Antecume Pata; Fermon et al. coll. 4 Jun. 2001. MNHN 1999- 1362, 4 spms, 113-154 mm TL, Saul, Duranton coll., 1983.

Japigny kirschbaum , French Guiana: Holotype, MNHN 2008-1201, 156 mm TL, Mana River , Saut Fracas, Oct. 1994, Keith et al. coll . Paratypes: MNHN 1999-1301 , 5 spms, 103-176 mm TL, Approuague drainage, Crique Japigny , 17 Nov. 1988, Boujard et al. coll .; MNHN 2000-5914 , 1 spm, 206 mm TL; Maroni drainage, Litany, Oct. 2000, Jégu et al. coll ; MNHN 2000-5911 , 2 spms, 159 and 220 mm TL, Maroni drainage, Tampoc at Saut Pierkuru, Oct. 2000, Keith et al. coll .; MNHN 2000-5915 , 3 spms, 136-174 mm TL, Maroni drainage, Litany, Oct. 2000, Jégu et al. coll .; MNHN 2006-1793 , 4 spms, 105-136 mm TL, Maroni drainage, Litany, Oct. 2000, Jégu et al. coll .; MNHN 1999-1334 , 7 spms, 72-160 mm TL, French Guiana , Mana drainage, Saut Fracas, Oct. 1994, Keith et al. coll .; MNHN 2000-5954 , 2 spms, 99 and 111 mm, Alizarin rot stained specimens, Maroni drainage, Litany, Oct. 2000, Jégu et al. coll .

Rhabdolichops jegui , French Guiana: Holotype, MNHN 1999-1024, 215 mm LT, Litany River (Maroni), Antecume Pata, Oct. 1998, Jégu coll. Paratypes: MNHN 1998-1576, 113 mm LT, Litany River (Maroni), Antecume Pata, Oct. 1998, Jégu coll. ; MNHN 1999-1025 , 198 , 5 mm LT, Litany River (Maroni), Antecume Pata, Oct. 1998, Jégu coll. ; MNHN 1999-1026, 202 mm LT, Litany River (Maroni), Antecume Pata, Oct. 1998, Jégu coll. ; MNHN 1998-2010, 277 mm LT, Mana River , Saut Fracas, Sep. 1994 , Keith et al., coll .

Material examined

Six specimens from French Guiana .

Holotype. - MNHN: 2000-5927, 271 mm TL, French Guiana, Maroni drainage, Tampoc River, Saut Pierkuru (2°49’N; - 53°32’W), Oct. 2000, Jégu et al. coll.

Paratypes. - MNHN 2001-2284 , 1 spm, 271 mm TL, French Guiana, Maroni drainage, Litany River Saut Aliminaemen (3°17’N; - 54°4’W), 5 Apr. 2001, Fermon et al. coll .; MNHN 2003-0014 , 1 spm, 232 mm TL, French Guiana, Maroni drainage, Litany, Antecume Pata, 30 Oct. 2002, Fermon et al. coll .; MNHN 2003-0018 , 2 spms, 322-331 mm TL, French Guiana, Maroni drainage, Litany; 23 Oct. 2000, Fermon et al. coll .; MNHN 2003-0013 , 1 spm, 222 mm TL; Alizarin rot staining ( Taylor and Van Dyke, 1985); French Guiana, Maroni drainage, Litany, Antecume Pata, 24 Oct. 2002, Fermon et al. coll .

Diagnosis

In preserved specimens, the new species is characterized by a grey colour with several longitudinal lightly dark lines, the lowest being regularly striped ( Fig. 1 ); 13-14 precaudal vertebrae; 184-187 anal fin rays in the undamaged specimens (see below “regeneration of the caudal skeleton”); a triangular head with a snout short (less than one third of the head length), a terminal mouth and the anus located straight below the eyes.

Description

Morphometrics are presented in tables I and II. The tail of two specimens, MNHN 2001-2284 and MNHN 2003- 0013 , was cut, so several morphometric and meristic data are lacking .

Anal rays 184 (184-187); pectoral rays ii16 (ii16-19); 13 (13-14) precaudal vertebrae and a total number of 79 (56-84) vertebrae; three or four rib-like bones [sensu Lundberg and Mago-Leccia (1986); = loose hemal spines sensu De La Hoz and Chardon (1984)] ( Fig. 2 ). In paratypes, the variability of total number of anal fin rays and vertebrae results from regenerative peculiarities of the caudal part after accidental or predatory wound (see below). On undamaged specimens, the caudal appendage is flattened. The body is totally covered with cycloid scales.

Mouth terminal and snout short at the tip of a triangular head. Body and tail compressed; head length 6,6-7,2% (H/T) of length to anal fin; greatest body depth 5% (H/G) of length to anal fin and about 7-8.5% (B/G) of total length; head depth at nape 1.3-1.6% (C/S) and at eyes 1.7-2.1% (C/R) of its length; snout length 2.3-3% (C/K), interocular distance 4.5-6% (C/M) and postorbital distance 1.5-1.7% (C/N) of head length; distance from eye to posterior nare 4.8-7.3%(C/P), internarinal distance 8-12.1% (C/O) and distance from tip of snout to posterior nare 4.4-5.6% (C/Q) of head length; eye diameter 6.1-8.7% (C/L) of head length; mouth small, its gape 3.3-6.6% (C/U) of head length; snout short 2.4-3% (C/K) of head length and mouth terminal; anus located straight below the eyes; gill opening 2.4-3.3% (C/V) of head length; origin of anal fin behind pectoral fin base.

Figures

Figure 1. - Distocyclus guchereauae. Holotype MNHN 2000-5927, 271 mm TL, Maroni, French Guiana; A: Photograph (C. Ferrara); B: X-ray.

Figure 2. - Distocyclus guchereauae. Paratypes X-ray. A: MNHN 2003- 0014; B: MNHN 2003-0013. Detail of the posterior abdominal region showing respectively three and four rib-like bones (arrowheads). The arrow points to the first hemal spine. Scale bars = 10 mm.

Figure 3. - Distocyclus guchereauae. Paratypes X-ray (MNHN 2003-0018). Upper specimen normal (331 mm TL); lower specimen regenerated (322 mm TL). In the regenerated tail, an ossified rod developed from the 65th vertebra and replaced caudal vertebrae; the regenerated anal rays stopped at the anterior part of the rod. Arrows point to the end of the anal fin; arrowheads point to the articulation of the bony rod with the last true vertebrae.