New species of miniature fish from Marajó Island, Pará, Brazil, with comments on its relationships (Characiformes: Characidae)

Abstract

A new miniature species of the family Characidae from Marajó Island, Pará State, Brazil is described and assigned to the genus Tyttobrycon. The new species can be distinguished from its congeners primarily by having multicuspid teeth on jaws, and additionally by having the combination of 5-7 premaxillary teeth, dorsal fin only with scattered melanophores and the presence of an adipose fin.Uma espécie nova miniatura da família Characidae da Ilha do Marajó, Pará, Brasil, é descrita e atribuída ao gênero Tyttobrycon. A espécie nova pode ser diferenciada dos congêneres principalmente por ter dentes multicuspidados nas maxilas e adicionalmente por ter a combinação de 5-7 dentes no pré maxilar, nadadeira dorsal apenas com pequenos cromatóforos escuros dispersos e presença de nadadeira adiposa.

Osteology of Tucanoichthys tucano Géry and Römer, an enigmatic miniature fish from the Amazon basin, Brazil (Teleostei: Characiformes: Characidae)

“…Further reduction in the infraorbital series is usually restricted to one or two missing infraorbitals of those that appear late in the ontogeny of Salminus (Mattox et al 2014), infraorbital 4 and/or 6 (e.g., Weitzman 1954;Vari 1979Vari , 1989Weitzman and Fink 1983;Weitzman and Malabarba 1999;Zanata and Vari 2005;Langeani and Serra 2010;Mirande 2010Mirande , 2019Mattox and Toledo-Piza 2012). Extreme reduction in the infraorbital series is rare and includes loss of infraorbitals 4-6 as described here and already reported for miniature characids belonging to other genera such as Iotabrycon (Roberts 1973), Paracheirodon Géry (Weitzman and Fink 1983), Spintherobolus Eigenmann (Weitzman and Malabarba 1999), Amazonspinther Bührnheim, Carvalho, Malabarba and Weitzman (Bührnheim et al 2008), Trochilocharax Zarske (Zarske 2010), Tyttobrycon (Marinho et al 2013;Abrahão et al 2019) and Priocharax (Mattox et al 2016). Most species of the latter genus actually lack infraorbitals in their entirety (Weitzman and Vari 1987 The number of postcleithra in Tucanoichthys is also reduced and worth a comment here.…”

Genome Sequencing of the Japanese Eel (Anguilla japonica) for Comparative Genomic Studies on tbx4 and a tbx4 Gene Cluster in Teleost Fishes

“…Members of Siluriformes are armed with spines in the anal, dorsal, caudal, adipose, and paired fins [31,32,33]. Additionally, fin spines are characterized in some members of the Characiformes [34]. Gymnotiformes, although divergent from Siluriformes [35], is an outlier due to its absence of pelvic fins and dorsal fins.…”

On a remarkable sexual dimorphic trait in the Characiformes related to the olfactory organ and description of a new miniature species of Tyttobrycon Géry (Characiformes: Characidae)

“…Marinho et al . [26] redefined the genus to include T . marajoara , a species presenting all characters used by Géry [23] to raise the genus, except the strictly conical teeth in jaws (some multicuspid teeth occur in T .…”

“…Morphometric and meristic data follow Fink & Weitzman [3] and Menezes & Weitzman [27] with modification detailed in Marinho et al . [26]. Standard length (SL) is given in millimeters (mm).…”

“…xeruini Géry (from rio Negro basin), and T . hamatus Géry (from tributaries of upper Rio Amazonas) [26]. Species of this genus are characterized by a combination of putative paedomorphic features accompanied by pronounced sexually dimorphic traits, which are commonly found in other small characids such as: small size, lateral line with few perforated scales, pseudotympanum conspicuous, caudal fin not scaled, anal fin with few rays with base often keeled in the males, presence of bony hooks in the anal fin, fontanels broad, antorbital and infraorbital 3 well developed, infraorbitals 4–6 absent, mouth supero-terminal, snout and maxilla short, no external teeth, ascending process of premaxilla short (Géry 1973), maxilla and premaxilla with conical or tricuspid teeth in one series (Marinho et al, 2013).…”