Re-validation of Otocinclus arnoldi Regan and reappraisal of Otocinclus phylogeny (Siluriformes: Loricariidae) Author A, Pablo Lehmann Author Mayer, Fernanda Author Reis, Roberto E. text Neotropical Ichthyology 2010 8 1 57 68 journal article 1982-0224 Otocinclus mimulus Axenrot & Kullander, 2003 Fig. 4 Otocinclus mimulus Axenrot & Kullander, 2003: 251 . Type locality: Paraguay : Departamento Caaguazú : río Paraná drainage, small stream (arroyo) at Estancia María Belén , 8 km from Colonel Patricio Colman ; 25°40’13”S 55°5’52”W . Holotype : MNHNP uncatalogued (ex NRM 43480 ), 34.1 mm SL [ Holotype originally cited as MNHNP uncat.]. Diagnosis. Otocinclus mimulus is distinguished from all other Otocinclus species except O . arnoldi , by having five branched rays in the pectoral-fin ( vs . six branched pectoral-fin rays), and except from O . arnoldi and O . xakriaba by having the prootic involved in the contact with the hyomandibular articular condyle ( vs . only compound pterotic contacting the hyomandibular articular condyle). It is distinguished from O . arnoldi by having an elevated patch of enlarged odontodes on the postero-dorsal parieto-supraoccipital tip and typically having 16-17 caudal vertebrae (see Table 2 ; vs . having a not elevated patch of enlarged odontodes on the parietosupraoccipital and having 15 caudal vertebrae). It is further distinguished (except for O . affinis , O . hasemani , O . xakriaba , O . arnoldi , and O . flexilis ) by possessing an iris operculum, and (except for O . affinis and O . xakriaba ) by having an elevated patch of enlarged odontodes on the postero-dorsal parietosupraoccipital tip. It is also distinguished from all remaining Otocinclus species (except for O . xakriaba , O . arnoldi , and O . flexilis ) by having a lateral trunk coloration composed of either a row of 3-6 distinct dark blotches or a distinct dark stripe extending from the compound pterotic to the base of the caudal fin, or a diffuse mixture of those two color patterns ( Fig. 4 ). Fig. 2. Color variation of Otocinclus flexilis . (a) and (b) : MCP 17414, SL = 37.6 and 44.6 mm respectively. (c) and (d) : MCP 18307, SL = 37.2 and 36.8 mm respectively. Distribution. Otocinclus mimulus is only known from the río Mondai in Paraguay , a left-bank tributary of the lower rio Paraná ( Fig. 5 ).