Lamontichthys stibaros Isbrücker & Nijssen, 1978

Lamontichthys stibaros Isbrücker & Nijssen, 1978 View in CoL

Fig. 14 View Fig

Lamontichthys stibaros Isbrücker & Nijssen, 1978b: 66-69 View in CoL , figs. 8 and 9, 10d, 14, table Ic, Ii-j, IIIb [original description; type locality: Ecuador, “Prov. Pastaza, rio Amazon system, rio Bobonaza in Chicherota, 02°25’S 76°38’W, altitude aprox. 260-280 m, upper rio Pastaza ”]; Isbrücker, 1980: 92 [listed]; Ortega & Vari, 1986: 17 [literature compilation; Peru]; Burgess, 1989: 426-427 [listed; description]; Barriga, 1991: 66 [literature compilation; Oriental Ecuador]; Ferraris & Vari, 1992: 27 [ type listed]; Eschmeyer, 1998: 1611 [listed]; Isbrücker, 2001: 29 [listed]; Ferraris Jr., 2003: 336 [listed]; Ferraris Jr., 2007:264 [listed]; Sullivan et al., 2006: [Siluriform higher-level relationships; molecular data, specimen not examined].

Diagnosis. Lamontichthys stibaros differs from all other species of the genus, with the exception of L. avacanoeiro and L. parakana , in the lack of plates on the anterior tip of the snout ( vs. anterior portion of snout totally covered with plates or with an inconspicuous naked area), in the teeth with long cusps ( vs. short) ( Fig. 3 View Fig ), and in the lower lip semi-oval shaped ( vs. semicircular) ( Fig. 3 View Fig ).

Lamontichthys stibaros differs from L. avacanoeiro and L. parakana in the longer first branched dorsal-fin ray (29.7- 36.8%, vs. 22.6-31.0% SL), in specimens larger than 70 mm SL. It further differs from L. avacanoeiro in the longer first branched pectoral-fin ray (21.7-25.1%, vs. 19.2-22.0% SL) and from L. parakana in the narrower head (89.1-101.4%, vs. 101.3- 106.1% HL).

The presence of 19 to 20 lateral plates along the mid-ventral series ( vs. 14 to 18) and the longer dentary (18.6-23.2%, vs. 11.5- 17.3% HL) in specimens larger then 70 mm SL also distinguishes L. stibaros from L. filamentosus and L. llanero . Lamontichthys stibaros differs from L. maracaibero in having more than one plate between the base of the last pelvic-fin ray and the anterior border of the anus ( vs. one plate) ( Figs. 1 View Fig and 5 View Fig ) and in the uniform color pattern of the fins ( vs. with brown and gray spots). Morphometric and meristic data are presented in Table 3 View Table 3 .

Geographic distribution. Upper rio Amazonas basin ( Fig. 2 View Fig ). Lamontichthys stibaros occurs in sympatry with L. filamentous in the drainages of río Santiago, río Marañón and río Ucayali, in Peru.

Material examined ( 25 specimens; 27.2-172.8 mm SL): Peru: Amazonas: LACM 39897-1 About LACM , 3, 42.2-89.5, río Santiago ; LACM 39884-3 About LACM , 2, 100.2-120.1, Marañón, río Santiago ; LACM 39647-1 About LACM , 1, 172.6, Marañón, río Cenepa , close to río Tujushiku. Ayacucho: ROM 47093 , 2, 122.6-150.1, near to confluence between río Mantaro and Tambo Apurimac . Ucayali: FMNH 84137 About FMNH , 7, 27.2-58.2, río San Alejandro ; FMNH 84131 About FMNH , 2, 43.8-47.3; FMNH 84112 , 3, 63.3- 86.6, río San Alejandro ; FMNH 84111 About FMNH , 6, 49.3-100.1, 1 cs *, 62.4, río San Alejandro .