Rhinolekos, Martins & Langeani, 2011

Martins, Fernanda de Oliveira & Langeani, Francisco, 2011, Rhinolekos, a new genus with three new species of Hypoptopomatinae (Siluriformes: Loricariidae) from upper rio Paraná, Neotropical Ichthyology 9 (1), pp. 65-78 : 66

publication ID

https://doi.org/10.1590/S1679-62252011000100005

persistent identifier

https://treatment.plazi.org/id/5F4887C1-FFC5-CB4A-150A-57CEFA423128

treatment provided by

Carolina

scientific name

Rhinolekos
status

gen. nov.

Rhinolekos View in CoL View at ENA , new genus

Type species. Rhinolekos britskii View in CoL , new species.

Diagnosis. Rhinolekos differs from all other Hypoptopomatinae ( sensu Schaefer, 1998) (except Microlepidogaster Eigenmann & Eigenmann ) by having the anterior portion of the compound supraneural-first dorsalfin proximal radial contacting the neural spine of the 9 th or 10 th vertebrae ( Fig. 1 View Fig ) ( vs. 8 th in Epactionotus Reis & Schaefer and 7 th in all other hypoptopomatines). Also, Rhinolekos can be readily distinguished from the remaining Hypoptopomatinae (except Gymnotocinclus anosteos Carvalho, Lehmann & Reis and Acestridium Haseman ) by the presence of the lateronasal plate, a large plate between the second infraorbital plate and the nasal opening, anteriorly projected, surrounding the nostril ( Fig. 2 View Fig ). Rhinolekos differs from Gymnotocinclus anosteos by having: dermal plates covering most of the body ( vs. extreme reduction of body dermal plates); lateral connecting bone fused to the lateral body plates ( vs. absence of lateral connecting bone); bifid hemal spines on caudal vertebrae posterior to first anal-fin proximal radial present ( vs. bifid hemal spines absent); all lateral body dermal plates with odontodes posteriorly curved, including the last ones on the caudal peduncle ( vs. odontodes on last dermal plates dorsally or anteriorly curved); maxillary barbel reduced, free from lower lip ( vs. adnate to lower lip). Furthermore, Rhinolekos differs from Acestridium by having: preopercle emergent to skin surface and visible externally ( vs. preopercle not emergent and not visible externally in all Hypoptopomatini taxa, including Acestridium ); head and body relatively wide, not depressed ( vs. head and body very slender, depressed); anterior margin of snout markedly rounded, without projection ( vs. snout with a conspicuous spatulate projection); dorsal-fin insertion slightly posterior to pelvic-fin base ( vs. dorsal fin placed well posterior to pelvic fin and just anterior to anal-fin origin).

Rhinolekos is similar to Microlepidogaster and Pseudotocinclus Nichols , concerning general body shape and may be phylogenetically related with these genera. However, Rhinolekos differs from Microlepidogaster by having ventral surface of pectoral girdle exposed only laterally ( vs. totally exposed); arrector fossae partially enclosed, with opening relatively large, extending laterally halfway towards pectoral-fin base ( vs. opening reduced). Additionally, Rhinolekos differs from M. perforatus by the absence of the median rostral plate ( vs. presence); by presenting the pectoral-fin axillary slit only in juvenile specimens ( vs. pectoral-fin axillary slit present, even in adult specimens); paired anterior process of the compound supraneural-first dorsal-fin proximal radial bone absent ( vs. present, linking the supraneural with the supraoccipital via ligament); median plate series continuous to the caudal-fin origin ( vs. median plate series truncated, ending before the caudal-fin base), and iris operculum present ( vs. absent). Finally, Rhinolekos differs from Pseudotocinclus by having the caudal peduncle roughly rounded in cross section ( vs. caudal peduncle distinctly square in cross section); longitudinal crests in supraoccipital absent ( vs. present); fourth infraorbital expanded ventrally ( vs. not expanded).

Distribution. Rhinolekos is restricted to streams of the rio Paranaíba drainage, Goiás State, central Brazil ( Fig. 3 View Fig ).

Etymology. The generic name is a combination of the greek, rhinos = nose, nostril and lekos = plate, in reference to presence of the lateronasal plate. Gender masculine.

Key to species of Rhinolekos View in CoL

1. Premaxillary and dentary accessory teeth present; caudal peduncle shallow (7.7-8.7% of SL); 18-20 (mode 19) middorsal plates........................................ Rhinolekos schaeferi View in CoL

1’. Premaxillary and dentary accessory teeth absent; caudalpeduncle deep (greater than 9.0% of SL); 21-27 (mode 22 in R. britskii View in CoL and 24 or 25 in R. garavelloi View in CoL ) mid-dorsal plates........................................................................................2

2. Transverse dark band in pectoral, pelvic and anal-fin rays present; thoracic length 14.7-18.0% SL; 24-28 dorsal plates....................................................... Rhinolekos britskii View in CoL

2’. Transverse dark band in pectoral, pelvic and anal-fin rays absent; thoracic length 18.1-20.8% SL; 30-35 dorsal plates................................................ Rhinolekos garavelloi View in CoL

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