es, Posadas). IBIGEO-I (Instituto de Bio y Geociencias del NOA- Ictiología, Salta, Argentina)
The electronic edition of this work follows with the requirements of the International Code of Zoological Nomenclature, and hence the new names contained herein are available under that Code from the electronic edition of this article. This published work and the nomenclatural acts it contains have been registered in ZooBank, the online registration system for the ICZN. The ZooBank LSIDs (Life Science Identifiers) can be resolved and the associated information viewed through any standard web browser by appending the LSID to the prefix “http://zoobank.org/”. The LSID for this publication is: urn:lsid:zoobank.org:act:D4B81E7D-0D04-4907-852B-A36931736CBE
Trichomycterus ytororo, new species
Argentina, Misiones, Jardín América, Tabay stream, Paraná River basin.
Paratype c&s specimen, CI–FML 7241, 67.3 mm SL. Abbreviations: DPR: dorsal procurrent caudal-fin rays, PH+H1+2 = lower caudal plate comprised by co-ossification of parhypural and hypurals 1 and 2; H4+5 = plate comprised by co-ossification of hypurals 4 and 5; pu1 + u1 = preural centrum 1 and ural centrum 1, pu2 = preural centrum 2; PS: pleurostile, VPR: ventral procurrent caudal-fin rays.
CI–FML 7240 (rd), 94.2 mm SL, Argentina, Misiones, Jardín America, Tabay Waterfalls, Paraná River basin, 27°00’00”S 55°10’44”W, November 2016, G. E. Terán, M. Benitez, F. Alonso, G. Aguilera & J. M. Mirande.
All collected with holotype. CI–FML 7241, 67.3–103.8 mm SL, (8 rd, 1 c&s). LGEP 542, 4, 64.6–107.3 mm SL, (2 rd, 1 c&s, 1ms). IBIGEO-I 354, 3, 60.9–79.2 mm SL, (3 rd).
Trichomycterus ytororo is distinguishable from all congeners by the presence of 31–35 dorsal caudal procurrent rays (Fig 3; vs. 29 or less). In addition, Trichomycterus ytororo exhibits two characters shared only by three congeners (Table 1; T. crassicaudatus, T. igobi, and T. stawiarski): the procurrent caudal-fin rays thickly ossified and rigid with a slender distal tip and the dorsal procurrent caudal-fin rays extending along the tips of 10–13 neural spines (Fig 3; vs. procurrent caudal-fin rays thin and flexible with the dorsal ones extending for less than eight neural spines tips). Trichomycterus ytororo can be further distinguished from T. crassicaudatus, T. igobi, and T. stawiarski by the number of branchiostegal rays (9 vs. 10–11). Trichomycterus ytororo can be further distinguished from T. igobi by the smaller head length (19.7–22.5% vs. 23.8–26.8% of SL), longest caudal peduncle (20.3–23.4% vs. 15.4–19.7% of SL) and 4–7 pores in the trunk canal of the laterosensory system (vs. two pores); from T. crassicaudatus by the caudal-fin distal margin rounded in adults (vs. forked), higher number of vertebrae (37–38 vs. 35–36), lower number of ventral procurrent caudal-fin rays (13 vs. 17–18), and the dorsal procurrent caudal-fin rays extending over the tips of 13 neural spines (vs. dorsal procurrent caudal-fin rays extending over the tips of 12 neural spines); and from T. stawiarski by the lower number of ventral procurrent caudal-fin rays (13 vs. 17), the higher number of pectoral-fin rays (i,7 vs. i,6), and lower number of vertebrae (37–38 vs. 39).
In addition to the above mentioned characters, Trichomycterus ytororo is distinguishable from congeners inhabiting the Paraná-Paraguay system by: 1) the number of pectoral-fin rays (i,7 vs. i,5 in T. mboycy Wosiacki & Garavello, T. naipi Wosiacki & Garavello, T. piratymbara Katz, Barbosa & Costa, T. taroba Wosiacki & Garavello; i,5–6 in T. davisi (Haseman), T. perkos Datovo, Carvalho & Ferrer; i,6 in T. castroi de Pinna, T. maracaya Bockmann & Sazima, T. paolence (Eigenmann), T. papilliferus Wosiacki & Garavello, T. pauciradiatus Alencar & Costa, T. pirabitira Barbosa & Azevedo-Santos, T. septemradiatus Katz, Barbosa & Costa; and i,8 in T. boylei (Nichols), T. dali Rizzato, Costa, Trajano & Bichuette, T. therma Fernández & Miranda). 2) First pectoral-fin ray not prolonged as filament (vs. first pectoral-fin ray prolonged as a long filament beyond the distal margin of the fin 