Simpsonichthys de Carvalho

Wilson J. E. M. Costa & Gilberto C. Brasil, 2006, Three new species of the seasonal killifish genus Simpsonichthys, subgenus Hypsolebias (Teleostei: Cyprinodontiformes: Rivulidae) from the rio Paracatu drainage, rio São Francisco basin, Brazil., Zootaxa 1244, pp. 41-55 : 53

[[ Simpsonichthys de Carvalho ]]

Discussion

In the most recent phylogenetic study (Costa, 2006), Simpsonichthys was divided into five subgenera: Xenurolebias Costa , Ophthalmolebias Costa , Simpsonichthys de Carvalho , Spectrolebias Costa & Nielsen , and Hypsolebias Costa . Hypsolebias is the most speciose clade of Simpsonichthys , including 24 species divided into four main clades: the S. magnificus species group , the S. notatus species group , the S. flammeus species group , and the S. antenori species group (Costa, 2006).

Simpsonichthys virgulatus possesses the frontal squamation A-patterned (Fig. 8) and a row of small bright blue spots on the distal margin of the dorsal fin in males, which are synapomorphic features for the S. notatus species group (Costa, 2006). This clade includes S. notatus (Costa, Lacerda & Brasil, 1990) , S. radiosus Costa & Brasil, 2004 ; S. similis Costa & Hellner, 1999 ; S. trilineatus , S. auratus , S. stellatus (Costa & Brasil, 1994) , S. rufus Costa & Nielsen, 2001 ; and S. nielseni Costa, 2005 . Among them, S. virgulatus shares, along with S. trilineatus and S. auratus , the presence of flanks bright golden, with rows of black round blotches in males (Costa, 2006). However, another derived feature described by Costa (2006) for the clade including S. trilineatus and S. auratus (i. e., brownish red pigmentation on the pectoral fin in males), is not present in S. virgulatus , suggesting that S. trilineatus is more closely related to S. auratus than to S. virgulatus .

Simpsonichthys fasciatus is a miniature species, only reaching a maximum adult size of about 20 mm SL. Individuals maintained in aquaria by the second author did not exceed this size after 10 months. This species is a member of the clade defined by Costa (2006) as the S. flammeus species group , diagnosed by having spatula-shaped anal fin in females. This clade includes S. flammeus (Costa, 1989) ; S. brunoi Costa, 2003 ; S. multiradiatus (Costa & Brasil, 1994) , S. alternatus and S. delucai . Among them, S. fasciatus is closely related to the clade including S. alternatus and S. delucai , which is diagnosed by the rounded anal fin in males and oblique bars on the dorsal fin in males.

Simpsonichthys gibberatus may be considered a member of the S. notatus species group , since it shares the apomorphic A-patterned frontal squamation with species of this assemblage. This supposed phylogenetic position is reinforced by the presence of a black spot on the anterocentral portion of the flank in some males, a condition also occurring in several species of the S. notatus group (i. e., S. notatus , S. radiosus , S. similis , S. trilineatus , S. auratus , and S. virgulatus ). However, some incongruence to this hypothesis in noted by the absence of a row of small bright blue spots on the distal margin of the dorsal fin in males, a synapomorphy of the S. notatus group (Costa, 2006), and the possession of gray bars on the flank in females, a condition considered plesiomorphic for Simpsonichthys and not occurring in other members of the S. notatus group (Costa, 2006).