Phenacorhamdia roxoi, Silva, 2020

Silva, Gabriel S. C., 2020, A new species of Phenacorhamdia Dahl 1961 (Siluriformes: Heptapteridae) from the Paranapanema River basin, southeastern Brazil, Zootaxa 4890 (2), pp. 275-282 : 276-280

Phenacorhamdia roxoi , new species

Figs. 1 , 4a,b,c ; Table 1

Phenacorhamdia tenebrosa — Azevedo-Santos, Pelicice & Henry, 2020 [inventory].

Holotype. MZUSP125819 , 63.8 mm SL, São Paulo State, Botucatu Municipality, Córrego Hortelã, Pardo River , Paranapanema River , Upper Paraná River basin, -22.941178º, -48.584397º, 25 May 2019, J. Lima, L. Reia, G.S.C. Silva.

Paratypes. All from Brazil, São Paulo State, Paranapanema River basin, Upper Paraná River basin: LBP 1994, 11, 24.1‾ 83.7 mm SL, (3 c&s, 42.9‾ 83.7 mm SL), Botucatu , Córrego Hortelã , -22.941178º, -48.584397º, 16 Dec 2003, C. Oliveira. LBP 2719, 1, 84.7 mm SL, Botucatu , Ribeirão da Quinta , -23.108528º, -48.505028º, 26 Apr 2005, R. Devidé. LBP 3512, 1, 66.1 mm SL, Botucatu , Córrego Hortelã , -22.941178º, -48.584397º, 17 may 2008, R. Devidé. LBP 3596, 4, 54.4‾ 74.1 mm SL, Botucatu , Córrego Hortelã , -22.941178º, -48.584397º. LBP 5092, 2, 41.2‾ 45.2 mm SL, Itatinga , Córrego dos veados, 25 may 2007, R. Paiva. LBP 8247, 2, 48.0‾ 53.3 mm SL, São Miguel Arcanjo , Ribeirão Guararema , -23.996944º, -48.015833º, 20 Feb 2009, C.H. Zawadzki, C.A.M. Oliveira. LBP 24478, 1, 57.8 mm SL, Botucatu , Riacho da Mata , -22.923333º, -48.544722º, 11 Jul 2016, P.S. Manoel, S.C. Almeida, H.A. Rodrigues. LBP 28707, 4, 41.6‾ 55.8 mm SL, same data as holotype. LBP 29850, 2, 57.7‾ 68.6 mm SL, (1 c&s, 54.6 mm SL), Botucatu , Córrego Hortelã , -22.923333º, -48.544722º, 01 Feb 2020, G.S.C. Silva, F.F. Roxo. LBP 29534, 1, 39.3 mm SL, Angatuba , Rio Itapetininga , -23.544250º, -48.311583º, 18 Aug 2020, V. M. Azevedo-Santos. MZUSP 125820 , 2 , 45.2 ‾ 52.8 mm SL, same data as holotype. NUP 22697, 2, 44.2‾ 56.2 mm SL, Botucatu, Córrego Hortelã, -22.923333º, -48.544722º, 01 Feb 2020, G.S.C. Silva, F.F. Roxo .

Diagnosis. Phenacorhamdia roxoi differs from its congeners, by having of 45‾46 vertebrae (vs. 38‾ 39 in P. nigrolineata ; 39 in P. taphorni ; 41 in P. tenebrosa ; 41‾ 43 in P. anisura , P. boliviana , and P. somnians ; 44 in P. cabocla ; 47‾ 48 in P. provenzani ; 53‾ 55 in P. tenuis ). The new species can be easily distinguished from P. unifasciata by having an entirely dark-brown body (vs. yellowish body, with a wide dark band along the upper side) and eight branched rays in upper lobe of caudal fin (vs. six). Additionally, P. roxoi differs from P. hoehnei , P. macarenensis and P. nigrolineata by the presence of seven branched rays in pectoral fin (vs. 5‾ 6 in P. hoehnei ; six in P. macarenensis and P. nigrolineata ). It is further distinguished by the presence of 8 branched anal-fin rays (vs. six in P. macarenensis and 9‾ 10 in P. provenzanoi ); and by having the first basal radial inserted at the 13th vertebrae (vs. 12th in P. tenebrosa ).

Description. Morphometric and meristic data are summarized in Table 1. Small-sized (maximum 84.7 mm of SL). Head depressed, dorsally covered by skin with small papillae. Snout short and rounded in dorsal view. Dorsal profile of head straight from snout tip to occipital region. Eye not free rim, dorsally, anterior of midpoint of head. Mouth small. Premaxillary teeth arranged in rectangular patch with 11-12 irregular rows of small conical teeth. Lower jaw longer than upper jaw. Dentary teeth arranged in a rectangular patch with small conic and tubular teeth. Maxillary barbel reaching base of third pectoral-fin ray base, when depressed. Mental barbels not reaching pectoralfin base when adpressed.Anterior and posterior nares tubular. Branchiostegal membranes free joined to isthmus only at anterior point, with seven or eight rays. Four to five gill rakers along anterior border of first ceratobranchial.

In dorsal view, body elongated and compressed at caudal peduncle ( Figure 1b ). Greatest body width at cleithral region, progressively narrowing anteriorly towards snout tip and posteriorly towards caudal fin. In lateral view, body depressed and convex in shape from end of head to dorsal-fin origin; slightly concave from dorsal-fin origin to adipose-fin origin; straight from adipose-fin origin to caudal peduncle. In lateral view, ventral profile straight and descending from snout tip to opercular region; slightly convex from opercular region to pelvic-fin origin; straight from that point to anal-fin origin; slightly concave from that point to lower procurrent caudal-fin ray origin. Precau-dal vertebrae 16(1)‾17(3) (nine supporting pleural ribs), caudal vertebrae 29(1)‾30(3), total vertebrae 45(1)‾46(3). First hemal spine on vertebra 16(1)‾17(3). Hemal spine of vertebrae 26(1)‾27(3) to 30(1)‾32(3) bifid. Neural and hemal spines of posterior vertebrae, nearly parallel to vertebral column, inclined less than 20º.

Pectoral fin with one simple ray and seven branched rays (20). First ray soft and longest. Distal margin of pectoral fin convex. Pelvic fin with i,5 rays. First pelvic ray shortest, second and third branched rays longest. Pelvic-fin origin anterior to dorsal fin origin. Dorsal-fin with i,6 rays. Dorsal-fin margin convex, its second and third branched rays longest. Unbranched dorsal-fin ray slightly convex. First basal radial inserted at neural spine of vertebrae 13thº (4), and last basal radial anterior to neural spine of vertebra 19 (4). Adipose-fin origin at vertical through fifth ray of anal fin. Anal fin with v,8 rays. Anal supported by 10 basal and 11 distal radials. Caudal skeleton with parhypural + hypurals 1 and 2 in ventral caudal plate; dorsal caudal plate with hypurals 3 and 4 fused, hypural 5 free, and a uroneural fused to compound centrum. Caudal fin forked with eleven (2) or twelve (2) dorsal procurrent rays; i,8+8,i principal rays; eleven (2) or twelve (2) ventral procurrent rays. Lower lobe of caudal fin longer (mean 28.2% of SL) than upper lobe (mean 23.4% of SL).

Laterosensory canal of head with simple tubes ending in single pores. Supraorbital sensory canal usually with five branches and pores: s1, s2, s3, s6 and s8. Supraorbital pore 1 medially adjacent to anterior nares. Supraorbital s2 and infraorbital i2 fused (forming complex s2+i2) at midway between anterior and posterior nares, S3 inside posterior nares, at notch of cutaneous membrane. s4 and s5 pore absent. Pore S6 fused at midline of the cranium, opening in a single pore (s6+s6). Pore s6+s6 absent in eleven individuals. The s8 at the posterior surface of the frontal. Infraorbital laterosensory canal with six branches pores: i1, i2, i3, i4, i5 and i6, with i2 fused to s2. Infraorbital pore i1 adjacent to anterior nares, between nares and maxillary barbel; i2+s2 posterior to maxillary barbel base. i3 at vertical through anterior orbit. i4 at vertical through posterior orbit. i5 posterior to eye. The pore i6 located behind the orbit. Preoperculomandibular canal with 12 lateral-line branches and pores: pm 1 in the medial portion of dentary; pm2, pm3 and pm4 aligned anteriorly to inner and outer mental barbel. Pore pm5 above to outer mental barbel base. Pore pm6 just behind to pm5. Pore pm7 and pm8 at vertical through anterior and posterior orbit respectively. Four pores in the preopercle region; pm9, pm10, pm11+po1, and po2.

Color in alcohol. Background color of dorsal and lateral region of head and trunk dark brown. Abdominal portion of body whitish. Ventral portion of head yellowish. Fin rays yellowish, and interradial membranes hyaline. Adipose-fin base dark brown, with distal margin hyaline. Barbels dark brown ( Fig. 1 and 4a,b,c ).

Distribution. Phencorhamdia roxoi is known from tributaries to Paranapanema River basin ( Fig. 2 ). The typelocality is at Córrego Hortelã, other sites are Riacho da Mata, Ribeirão da Quinta, Córrego dos Veados, Rio Itapetininga and Ribeirão Guararema.

Habitat. Phenacorhamdia roxoi was collected in shallow, clear waters and fast-flowing currents, with an underlying substrate of rock. The fishes collected were associated with pebbles ( Fig 3 ). The new species is found in syntopy with Hypostomus strigaticeps ( Regan 1908) , Cambeva diabola (Bockmann, Casatti & de Pinna 2004) , Neoplecostomus cf. botucatu Roxo, Oliveira & Zawadzki 2012 and Piabarchus stramineus ( Eigenmann 1908) .

Etymology. The species name roxoi honors Fábio Fernandes Roxo of Laboratório de Ictiologia de Botucatu, Setor Zoologia, Universidade Estadual Paulista, in recognition by its contributions on the knowledge of Neotropical Ichthyology. Fábio also helped to collect part of type series of the new species.

Figures

FIGURE 1. Phenacorhamdia roxoi, MZUSP 125819, 63.8 mm SL, holotype, from São Paulo State, Botucatu Municipality, Córrego Hortelã, rio Paranapanema, Upper Paraná River basin. (a) dorsal view, (b) lateral view and (c) ventral view.

FIGURE 2. Distribution of Phenacorhamdia roxoi. Red Star = holotype. White circles = paratype localities.

FIGURE 3. Habitat of Phenacorhamdia roxoi, a stream of the Córrego Hortelã, tributary of the Rio Turvo in Paranapanema River basin.

FIGURE 4. Left column Phenacorhamdia roxoi, paratypes: a) LBP 29850, 69.0 mm SL; b) LBP 28707, 50.0 mm SL; c) LBP 28707, 42.6 mm SL. Right column, Penacorhamdia tenebrosa, topotypes, LBP 29845, d) 45.7 mm SL; e) 37.4 mm SL f) 30.5 mm SL.