Rhyacoglanis paranensis, Shibatta & Vari, 2017

Shibatta, Oscar Akio & Vari, Richard P., 2017, A new genus of Neotropical rheophilic catfishes, with four new species (Teleostei: Siluriformes: Pseudopimelodidae), Neotropical Ichthyology 15 (2), No. e 160132, pp. 1-30 : 11-14

Rhyacoglanis paranensis , new species

urn:lsid:zoobank.org:act:258CF6F3-FB04-4283-8CC9-7986EDEFB2B3

Figs. 7-8; Tab. 3

Microglanis sp. - Castro, 1999:150-151 (comments on miniaturization and heterochrony).

Pseudopimelodus aff. pulcher , and New genus pulcher: Langeani et al., 2007:189 and 196 (occurrence in the upper rio Paraná basin).

Pseudopimelodus pulcher . - Birindelli, Shibatta, 2011:891-894 (description of gas bladder).

Holotype. MZUEL 14119 , 61.9 mm SL, Brazil, São Paulo, rio Piracicaba , 22º43’10”S 47º39’21”W, 25 Sep 2008, L. Giuliano-Caetano.

Paratypes. All from Brazil. Minas Gerais. MZUSP 36770 , 4 , 32.8-38.7 mm SL, Ituiutaba, Salto do Morais, rio Tijuco , 18º56’58”S 49º23’01”W, Oct 1985 - Feb 1986 , A. L. Godinho. Mato Grosso do Sul. MZUEL 14121 , 1 , 89.3 mm SL, Três Lagoas, Córrego Mimoso, tributary of rio Sucuriú , 19º03’8.67”S 52º58’52”W, 7 Jan 2004 , W, L. M. Cordeiro et al. MZUSP 22505 , 39 , 40.9 -16.0 mm SL, Três Lagoas, rio Paraná, in front of Jupiá , 20º15’00”S 51º07’00”W, Sep 1962 , Expedição do Departamento de Zoologia. MZUSP 24448 , 11 , 49.9 - 22.2 mm SL, Três Lagoas, Ilha Solteira , 25- 28 May 1972 , Expedição MZUSP. São Paulo. MCP 14442, 7 , 36.1-67.8 mm SL, rio Cubatão, tributary of rio Pardo, near Cajuru , ca. 21º18’S 47º1’W; 7 Nov 1989 , W, R. M. C. Castro. MZUSP 22931 , 20 , 35.3 - 23.8 mm SL, Pirassununga, rio Mogi Guaçu, Cachoeira de Emas , ca. 21º55’S 47º23’W, Feb 1964 , Expedição do Departamento de Zoologia. MZUEL 12159 , 12 , 33.7 - 27.6 mm SL, Pirassununga, rio Mogi Guaçu , Cachoeira de Emas , 21º55’38”S 47º22’3”W; 4 Aug 1994 , L. Giuliano Caetano. MZUSP 107932 , 14 , 62.5 - 39.4 mm SL, Ipeúna, rio Passa Cinco, tributary of Rio Tietê , 22º25’30”S 47º41’49”W, 1 Jun 2006 , O. Moreira Filho et al. MZUEL 2381 , 1 , 38.3 mm SL, Ourinhos, rio Paranapanema , under railroad bridge, 23º00’36”S 49º54’18”W, 24 Jun 1992 , Duke Energy International. Paraná. MZUEL 6034 , 10 , 44.6 - 38.7 mm SL, Itambaracá, rio Paranapanema , fish ladder at Canoas I Dam, 22º56’24”S 50º31’7”W, 17 Mar 2005 , Equipe de Coleta de Peixes da UEL. NUP 3844 , 2 , 41.8 -44.0 mm SL, Santa Fé, rio Bandeirante do Norte , tributary of Rio Pirapó , 23º00’26”S 51º47’54”W, 13 Sep 2004 , NUPELIA. MZUEL 14120 , 89 , 38.2 - 32.2 mm SL, Cornélio Procópio, rio Laranjinha , 23°17’50”S 50°28’43”W, 21 Jan 2009 , Galindo et al.

Diagnosis. Rhyacoglanis paranensis differs from R. annulatus by possessing a uniformly dark caudal peduncle band (vs. a band with an unpigmented central region), a wide subdorsal band (vs. a narrower band), a lower number of total vertebrae (31-33 vs. 34-35), a greater distance between the pelvic-fin and anus (9.9-17.3 vs. 8.2-9.6% SL), and a shorter distance between the anus and anal fin (6.5-12.7 vs. 15.8-16.2% SL). Rhyacoglanis paranensis is differentiated from R. epiblepsis by the pointed caudal-fin lobes (vs. rounded lobes), presence of only a few dark body spots (vs. many body spots of less intense pigmentation). Rhyacoglanis paranensis differs from R. seminiger by possessing distinctly separated subdorsal and subadipose bands (vs. fused bands), continuity between dark pigmentation on the caudal-fin lobes (vs. separation of the pigmentation on those lobes) and presence of discrete, dark transverse pectoral and pelvic-fin stripes (vs. fins largely uniformly dark). Rhyacoglanis paranensis differs from R. pulcher in the lack of dorsal and ventral confluence between the dark subdorsal and subadipose bands (vs. dorsal and ventral continuity of those bands), in the lack of confluence between subadipose and caudal-peduncle bands (vs. dorsal and ventral continuity of those bands) and possession of lower number of total vertebrae (31-33 vs. 33-35).

Description. Body proportions in Tab. 3. Body depressed from snout tip to dorsal-fin origin; progressively more compressed from that point to caudal-fin base. Dorsal profile of head and anterodorsal portion of body nearly straight from snout tip to dorsal-fin origin but slightly concave along occipital region. Dorsal-fin base nearly straight with slight posteroventral incline. Body profile nearly straight from end of dorsal-fin base to adipose-fin origin. Ventral profile of head and body convex from lower jaw margin to end of anal-fin base, almost straight from anus to anal-fin origin. Caudal peduncle profile concave dorsally and ventrally.

Head depressed; wider than long. Anterior outline of head convex in dorsal view. Head with undeveloped unculiferous tubercles laterally and dorsally. Mouth terminal, wide; width greater than one-half HL. Upper jaw slightly longer than, or same length as, lower jaw. Lips thick, well developed mainly close to rictus. Premaxillary tooth plate posterolaterally pointed. Anterior nostril located immediately posterior to vertical through rictus. Eye small, superior, covered by skin, slightly posterior to anterior one-third of HL. Opercular membrane well developed; margin reaching pectoral-fin origin. Maxillary-barbel base enlarged. Tip of adpresssed barbel reaching pectoral-fin origin. Adpressed inner mental barbel extending posteriorly slightly beyond outer mental-barbel base but falling short of barbel tip. Tip of adpressed outer mental barbel reaching margin of opercular membrane but falling short of pectoralfin origin.

Dorsal fin trapezoidal with distal margin rounded and longest ray equal to dorsal-fin base. Dorsal-fin origin immediately posterior to anterior one-third of body, but anterior to one-half of SL. Tip of adpressed dorsal fin falling short of midpoint between dorsal-fin insertion and adipose-fin origin. First dorsal-fin ray (spinelet) small, rigid, and forming dorsal-fin spine-locking mechanism. Second dorsal-fin ray spinous; smooth anteriorly and with retrorse serrations posteriorly. Dorsal-fin rays I,6*(29). Adipose fin long; base length similar to that of dorsal fin; posterior extremity free and angular. Pectoral-fin profile triangular overall; posterior margin semi-circular. Tip of adpressed pectoral fin falling short of pelvic-fin origin. First pectoral-fin ray a strong, rigid spine with retrorse serrations along entirety of anterior and posterior margins. Posterior serrations somewhat larger than anterior serrations. Tip of pectoral-fin spine notched ( Fig. 3c). Pectoral-fin rays i,6*(27). Pelvic fin almost triangular with posterior margin rounded. Pelvic-fin origin at vertical through base of penultimate dorsal-fin ray. Tip of adpressed pelvic-fin reaching adipose-fin origin. Pelvic-fin rays i,5*(31). Analfin margin rounded posteriorly. Anal-fin base shorter than adipose-fin base. Anal-fin rays iii,5*(2), iii,6(6), iii,7(1), iv,5(2), iv,6(16), or iv,7(2). Caudal fin forked with lobes pointed; ventral lobe slightly longer than dorsal lobe. Principal caudal-fin rays i,6,7,i(1), i,6,7,ii(2), or i,6,8,i*(29). Dorsal procurrent rays 12(2), 13(10), 14(5), 15(8), 16*(2), 17(2), or 18(2); ventral procurrent rays 9(3), 10(5), 11(16), 12(3), or 13*(3).

Posterior cleithral process well developed, pointed, reaching vertical anterior of dorsal-fin origin. Axillary pore present. Lateral line complete. Total vertebrae 31(1), 32*(15), or 33(16). Ribs 8*(26), or 9(6). Gill rakers 0,1,4(1), 1,1,3*(4), 1,1,4(12), 1,1,5(13), 1,1,6(3), 2,1,3(2), 2,1,4(2), 2,1,5(4), or 2,1,7(1).

Color in alcohol and in life. Ground color light brown in alcohol; light orange in life ( Fig. 8). Head with dark spots on dorsal surface, opercle, and region ventral to orbit. Region

over adductor mandibulae muscle lightly colored. Iris dark in alcohol; light gray in life. Dark subdorsal band with irregular anterior and posterior margins; extending to ventral region of body but not contacting contralateral counterpart. Subadipose band with irregular anterior and nearly straight posterior margins. Lightly colored region between subdorsal and subadipose bands with scattered dark spots. Anterior margin of caudal-peduncle band nearly straight and posterior margin in shape of shallow, posteriorly open sideways V. Dorsal fin with dark pigmentation covering fin other than for distal one-fifth. Adipose fin with dark blotch centrally. Anal fin with dark basal spot and dark stripe on midsection; two regions conjoined posteriorly. Caudal fin hyaline basally with broad dark band across each lobe and lobe tips largely hyaline. Pectoral and pelvic fins hyaline except for transverse dark stripe on each.

Geographical distribution. Rhyacoglanis paranensis is only known from the upper rio Paraná basin in Brazil ( Fig. 4).

Etymology. The specific name, paranensis , is an adjective in reference to the occurrence of the species in the upper rio Paraná basin.

Conservation status. Several specimens of R. paranensis were obtained from collections, suggesting that the species is not rare. Furthermore, the geographic distribution of R. paranensis in the upper rio Paraná basin must be wide, as the localities cover a broad geographic region of approximately 500,000 km 2. The construction of several hydroelectric power plants along the upper rio Paraná will likely fragment the species distribution by destroying the preferred habitat in rapids, and represents a potential threat to R. paranensis . However, in light of the extent of occurrence exceeding 20,000 km 2, and lack of evidence indicating population decline or fluctuation, we recommend assigning R. paranensis an IUCN (2016) conservation status of Least Concern (LC).