A new Tatia ( Ostariophysi : Siluriformes : Auchenipteridae ) from the rio Iguaçu basin , Paraná State , Brazil

A new species of Tatia is described from the lower rio Iguaçu basin, Paraná State, Brazil. The new species is distinguishable from congeners by having large, irregular pale blotches over dark brown base coloration, absent longitudinal stripe, caudal fin with round to striate dark brown spots over light base in adults or entirely dark in juveniles, and by having a long humeral process. Sexual dimorphism of the new species is marked by differences among genital and urinary apertures, size proportions between upper and lower lobe of caudal fin, and size, width and presence of antrorse and retrorse spines on anal-fin rays.


Introduction
The genus Tatia was proposed by Miranda-Ribeiro (1911) who included two species: T. intermedia (Steindachner) and T. aulopygia (Kner).Recently Sarmento-Soares & Martins-Pinheiro (2008) diagnosed Tatia among the Centromochlinae by having the hyomandibula anterodorsally elongated, not contacting the narrow metapterygoid and, instead, connected to the trapezoidal quadrate, reduced anal-fin base in adult males, and compressed and deep caudal peduncle, with a middorsal keel posterior to adipose fin.Those authors also recognized 12 valid species widespread in cis-Andean South American basins.
Previous inventories in the rio Iguaçu basin (e.g.Garavello et al., 1997;Ingenito et al., 2004;Baumgartner et al., 2006) have recorded only two species of Centromochlinae, Glanidium ribeiroi Haseman, and a new species of Tatia.Many Tatia specimens also have been collected during frequent samples in the lower rio Iguaçu basin over the last few decades by the Núcleo de Pesquisas em Limnologia, Ictiologia e Aqüicultura (Nupélia), of the Universidade Estadual de Maringá.Tatia neivai has been recorded from the whole Paraná-Paraguay system, except the Iguaçu basin, where occurs a different and undescribed species referable to the genus Tatia (sensu Sarmento-Soares & Martins-Pinheiro, 2008).This species exhibits a unique color pattern among congeners and it is described herein as a new Tatia.Soares-Porto (1995) and measurements Sarmento-Soares & Buckup (2005) with the latter made on the left side of the specimens whenever possible, with calipers to the nearest 0.1 mm.Measurements of the subunits of the head are presented as percent of head length (HL) and those related to the body, including HL and subunits of the body as percent of standard length (SL).Meristic data included vertebrae, caudal-fin and procurrent rays which were taken from six male and six female specimens cleared and stained (c&s) according to procedures of Taylor & Van Dyke (1985).Five males and two females were also radiographed for helping osteological analyses.Vertebrae counts follow Sarmento-Soares & Martins-Pinheiro (2008).Counts from the holotype are indicated by an asterisk.Material is listed informing, in parentheses, the number of specimens in the lot from which counts and measurements were taken if that number is less than the total number of specimens in the lot, and their range of SL. aulopygia, T. dunni and T. intermedia) and 9 or 10 ribs (vs.7 in T. galaxias).Some specimens of T. jaracatia have brown caudal-fin dots arranged as stripes, which might be confused with pale striae to roundish dots on caudal fins of some T. neivai.However, T. jaracatia has three to five (mode = 4, n = 11) hemal spines with thicker distal portion, while T. neivai has two or three (mode = 2, n = 3), in addition to different color pattern of body above mentioned.Tatia jaracatia can be diagnosed from T. intermedia by presenting caudal fin uniformly dark brown or with several dark brown chromatophores irregularly widespread, forming roundish blotches, and rarely forming stripes, and the humeral process long, reaching or surpassing the vertical line through origin of dorsal fin (vs.caudal fin with the same color pattern of the body, and humeral process shorter, not reaching that line).

Counts follow
Description.Morphometric data are presented in Table 1.Body elongated and head slightly depressed.Dorsal profile of body slightly convex from snout tip to adipose fin and Color in alcohol.Base color of dorsal and lateral surfaces of head and trunk ranging from light to dark brown; base color of ventral region of head and trunk white, lacking dark chromatophores.Lateral surface of body having pattern of pale blotches ranging from large to small, round to oval, and arranged longitudinally, transversally, or non-uniformly (Fig. 1).Dorsal fin generally hyaline, with scattered dark chromatophores on central or distal portion of first and second branched rays.Pectoral fin hyaline.Pelvic and anal fins hyaline, darkly colored only close to the base.Caudal fin ranging from uniformly dark brown, chiefly in juveniles (Fig. 1c), to having brown asymmetrical or oval blotches, or also with diffuse dark chromatophores irregularly arranged, occasionally forming stripes.
Sexual dimorphism.Adult females of Tatia jaracatia have genital and urinary apertures separate, but very close together; and proximal radials of anal fin not fused.Adult males have genital and urinary openings separate as well, but the former is close to the first anal-fin ray origin, and the latter is at vertical line through pelvic-fin tip; upper lobe of caudal fin longer than inferior; three to five* hemal spines above proximal radials distally thicker; first unbranched anal-fin ray reaching about a half length of the second, third unbranched anal-fin ray longer and thicker than second and with two or three* antrorse spines along anterior edge of distal segments, Table 1.Morphometric data of the holotype (male) and paratypes of Tatia jaracatia, from the lower rio Iguaçu basin (n = 43, including holotype).SD: standard deviation.and first branched anal-fin ray with two retrorse spines along anterior portion of median segments (Fig. 2).Proportions between branched and unbranched fin rays differ among sexes as well, as mentioned above.
Distribution.The new species is known from the lower rio Iguaçu basin, upstream from the Iguaçu falls, Southern Brazil (Fig. 3).
Etymology.The species name, jaracatia, refers to the typelocality, rio Jaracatiá, lower rio Iguaçu basin.Jaracatiá is an indigenous name given to a fructiferous tree common in the region.A noun in apposition.

Discussion
Tatia jaracatia fits all given characters for the genus stated by Sarmento-Soares & Martins-Pinheiro ( 2008), but exhibits a peculiar trunk color pattern composed of conspicuous, irregular, pale blotches over a dark background.
Most species of Tatia (sensu Sarmento-Soares & Martins-Pinheiro, 2008) are distributed across the Amazon, Tocantins, and Orinoco rivers, and coastal drainages of the Guiana Shield.The only two more southerly distributed species are T. boemia and T. neivai from the Uruguay and Paraná rivers, respectively.These last two species share with T. jaracatia the absence of ribs on vertebra preceding the last rib-bearing vertebrae (Soares-Porto, 1998).This putative osteological synapomorphy suggests that all three Tatia species in the La Plata basin are monophyletic.
Given its apparent absence from the entire rio Paraná basin below Iguaçu Falls, T. jaracatia appears to be endemic to the rio Iguaçu above the falls.The rio Iguaçu above Iguaçu Falls has been described by several authors as relatively depauperate in overall fish diversity, but high in fish endemism, presumably due to isolating effects of the falls (Garavello et al., 1997;Júlio Jr. et al., 1997;Baumgartner et al., 2006).Several other new species putatively endemic to the region above the falls are currently in press or in preparation by us and other researchers, and we predict that further collecting effort in the headwaters of rio Iguaçu will likely yield additional new, endemic taxa.

Fig. 3 .
Fig. 3. Map of southeastern Brazil and adjoining regions, showing the type-locality of Tatia jaracatia (circle), rio Jaracatiá, and the geographical distribution of the species (dots), lower rio Iguaçu basin.Both symbols represent more than one lot and/or locality.