Ectrepopterus Fowler 1943

Malabarba, Luiz R., Bertaco, Vinicius A., Carvalho, Fernando R. & Litz, Thomas O., 2012, Revalidation of the genus Ectrepopterus Fowler (Teleostei: Characiformes), with the redescription of its type species, E. uruguayensis, Zootaxa 3204, pp. 47-60 : 49-50

Ectrepopterus Fowler 1943

Ectrepopterus Fowler 1943:313 (subgenus of Megalamphodus ; type species by original designation and monotypy: Megalamphodus uruguayensis ). Géry 1972:14 (redescription of the type species; new diagnosis for the subgenus). Géry 1977:586 (synonym of Megalamphodus ). Weitzman and Palmer 1997:234 (synonym of Hyphessobrycon ).

Diagnosis. The following unambiguous apomorphies obtained through equal weighting analysis diagnose Ectrepopterus (ordered according to their consistency indexes). Characters 62, 67, 168, and 310 were also found as unambiguous autapomorphies of Ectrepopterus in the implied weighting analysis.

- ( Ch. 168:2; ci = 0.33) Foramen in posterior region of metapterygoid that serves as passage for the ramus mandibularis of the trigeminus nerve forms an incomplete arch, bordered posteriorly by the hyomandibula ( Fig. 2 ). This foramen is situated entirely within the metapterygoid among characid fishes lacking a supraorbital. The condition found in Ectrepopterus is apomorphic, and a reversal, since the foramen opening posteriorly is found in several basal lineages of the Characidae (e. g. Brycon Müller and Troschel 1844 , Bryconops Kner 1858 , and Iguanodectes Cope 1872 ; see Mirande 2010). This condition was found homoplastically in Bryconamericus scleroparius (Regan 1908) and in Pseudocorynopoma doriae Perugia 1891 .

- ( Ch. 310:1; ci = 0.10) Pectoral-fin rays bearing hooks. Although the presence of hooks in the fin rays is a condition shared by most characid fishes ( Malabarba and Weitzman 2003), its presence in the pectoral fin rays is not usual and was found by parsimony as diagnostic for Ectrepopterus . It was found homoplastic in Astyanax cf. asuncionensis Géry 1972 , A. chico Casciotta and Almirón 2004 , A. lineatus (Perugia 1891) , A. troya Azpelicueta, Casciotta and Almirón 2002 , Bario steindachneri (Eigenmann 1893) , Bryconamericus iheringii (Boulenger 1887) , B. rubropictus (Berg 1901) , B. thomasi Fowler 1940 , Hyphessobrycon luetkenii (Boulenger 1887) , H. socolofi Weitzman 1977 , and Nematocharax venustus Weitzman, Menezes and Britski 1986 ( Mirande 2010) .

- ( Ch. 62:2; ci = 0.06) Posterior margin of second infraorbital posteroventrally oblique and second infraorbital ventrally bordering anterior region of third infraorbital ( Fig. 3 ). This condition is usually associated with a long maxilla, and is found homoplastic in Exodon paradoxus Müller and Troschel 1844 , Hollandichthys multifasciatus (Eigenmann and Norris 1900) , Oligosarcus spp., and several genera of the Characinae .

- ( Ch. 67:0; ci = 0.03) Fourth infraorbital ( Fig. 3 ) more developed longitudinally than dorsoventrally (versus longer dorsoventrally than longitudinally). Although apomorphic for Ectrepopterus , this character is broadly distributed among Characidae .

- ( Ch. 104:1; ci = 0.03) Ascending process of premaxilla reaching just anterior end of nasal (versus reaching at least one-third of length of nasal). Although apomorphic for Ectrepopterus , this character is broadly distributed among Characidae .

- ( Ch. 91:1; ci = 0.02) Lateral line interrupted (versus complete). Although highly variable in Characidae , this character was recovered as one of the autapomorphies for Ectrepopterus .

Figures

FIGURE 2. Ectrepopterus uruguayensis, UFRGS 8578, 37.4 mm SL, male. Lower and upper jaws showing the premaxilla (PMX), maxilla (MAX) and dentary (DEN), and suspensorium showing the foramen in posterior region of metapterygoid (MTP) forming an incomplete arch and bordered posteriorly by the hyomandibula (HYO), left side. Scale bar = 1 mm.

FIGURE 3. Ectrepopterus uruguayensis, UFRGS 8578, 37.4 mm SL, male. Infraorbital series (IO 1 – 6) and antorbital (AOR), left side. Scale bar = 1 mm.