Type species: Tomocichla underwoodi Regan, 1908
Distinctive characters: When Regan described Tomocichla, he just noted that it differs from Herichthys that the pelvic fins originate clearly behind the pectorals. Futher characteristics of Tomocichla include (Bussing, 1976; Stawikowski & Werner, 1998): elongated, laterally compressed body; slightly subterminal mouth; small (30-34) scales along the lateral line; 4-5 rows of scales on the cheeks; low anal fin spine counts (4-5); compressed jaw teeth; dark pigmentation dorsally, abruptly white below, purple coloration on lateral scales and dark stripes across the snout.
Species currently included:
|Tomocichla asfraci||C, A(Aquarium)|
|C=CRC Catalogue, A=Article|
Distribution: Atlantic and pacific versant of Nicaragua, Costa Rica and western Panama.
Behavior/ Ecology: Tomocichla species usually inhabit water with swift current.
Further information: There has been a lot of confusion regarding the correct names of the species in the genus. The main reason for the confusion was that Regan gave the same name to two different species both assigned to Tomocichla: In 1906 he named a cichlid from "Costa Rica" Herichthys underwoodi (now known as T. sieboldii (Kner, 1863) and only two years later in 1908 he named another cichlid from the Rio Iroquois (also Costa Rica) Tomocichla underwoodi (now known as T. tuba (Meek, 1912)). For a complete overview on this topic please refer to Bussing (1975) and a discussion in the Cichlid-L Archive (Part 1, Part2).
Bussing (1975) hypothesized that T. tuba and T. sieboldii derived from a common ancestor during the Pliocene. New data from molecular phylogenies indicate that T. sieboldii and T. tuba are not closely related (e.g. Martin & Bermingham, 1998). This view is also supported by the different characteristics of the fry and juveniles (Heijns, personal communication). Kullander (2003) maintains T. sieboldii in Tomocichla pending a more general revision of heroin cichlids. Further data from molecular phylogenies indicate that there might be more than one species behind what we call T. sieboldii today (Concheiro Perez, personal communication), a southern form from Panama (T. sieboldii s.s.) and a northern form from Costa Rica (T. punctatum or T. frontale, both names were introduced by Meek, 1909). So far, very little is known about the geographic variation of T. sieboldii that could support such a view. The same data also indicate that T. sieboldii might be closely related to Vieja tuyrensis, a species from the same biogeographical area. In fact, Concheiro et al. (2007) suggested to include the two species into a new genus.