Coptobrycon bilineatus (Ellis, 1911) (Characiformes: Characidae): redescription and comments on its phylogenetic relationships

Abstract

Coptobrycon bilineatus (Ellis, 1911) is redescribed on the basis of specimens from the District of Paranapiacaba, Municipality of Santo André, upper rio Tietê, and additional ones recently collected in a small coastal river system of Serra do Mar, very near the headwaters of the rio Tietê. The genus was compared to other Characidae lacking a supraorbital, and it seems to be more phylogenetically related to Grundulus based on the possession of various putative apomorphic character states related to: the absence of a rhinosphenoid and fourth, fifth (sometimes) and sixth infraorbitals; nasal pores separated; nares with up to six nasal lamellae; cephalic laterosensory system poorly developed on supraorbital and infraorbital series; and a globose scapula. Furthermore, Coptobrycon and Grundulus are characterized by the absence of the adipose fin, of the supraorbital laterosensory series on the parietal, and of the humeral spot, and by the reduction of lateral musculature in front of the first pleural rib and between the first and second pleural ribs. Biogeographic comments are also provided.Coptobrycon bilineatus (Ellis, 1911) é redescrita com base em exemplares provenientes do Distrito de Paranapiacaba, Município de Santo André, alto rio Tietê, e de um pequeno sistema costeiro da Serra do Mar, muito próximo às cabeceiras do rio Tietê. O gênero foi comparado com outros Characidae sem supraorbital e parece ser mais proximamente relacionado a Grundulus, pela posse de vários estados apomórficos de caracteres: ausência de rinoesfenoide e dos infraorbitais quatro, cinco (eventualmente) e seis; poros nasais separados e não confluentes; narinas com no máximo seis lamelas nasais; sistema látero-sensorial cefálico pouco desenvolvido nas séries supraorbital e infraorbital; e escápula globosa. Adicionalmente, Coptobrycon e Grundulus são também caracterizados pelas: ausências de nadadeira adiposa, da série látero-sensorial cefálica supraorbital e de mácula umeral, e pela redução da musculatura corpórea lateral à frente da primeira costela pleural e entre a primeira e a segunda costelas pleurais. Comentários biogeográficos são também apresentados.

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

“…Some of the missing bones in Tucanoichthys are also lacking in other miniature characiforms, such as the nasal in the alestid Lepidarchus adonis Roberts (Roberts 1966: 210), the characid Hyphessobrycon elachys Weitzman (Mirande 2010: 400), and all members of the characid genus Priocharax (Mattox et al 2016). The nasal is also missing in the small characid Coptobrycon bilineatus (Ellis) (Langeani and Serra 2010), and its widespread absence has been considered previously to be a product of convergent loss in some of the aforementioned genera (Mattox et al 2016). Along similar lines, loss of the extrascapular has likely also occurred independently in multiple lineages of miniature characids, including for example Iotabrycon Roberts (Roberts 1973), Tyttocharax Fowler and Xenurobrycon Myers and Miranda-Ribeiro (Weitzman and Fink 1985), and Priocharax (Mattox et al 2016).…”

“…Many small characiforms have reductions in the infraorbital series, and the lack of the supraorbital has been interpreted either as a synapomorphy of a large clade within the Characidae (e.g., Malabarba and Weitzman 2003) or as a synapomorphy of the Characidae when some taxa traditionally assigned to this family are removed and assigned family-level status (e.g., Oliveira et al 2011). 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).…”

A new Hasemania Ellis from the upper rio Paraná basin, with the redescription of Hasemania crenuchoides Zarske & Géry (Characiformes: Characidae)

“…Furthermore, Hasemania crenuchoides and H. uberaba lack the synapomorphies used to diagnose other characid groups lacking the adipose fin, e.g. a few Cheirodontinae (Malabarba, 1998); a few Xenurobryconini (Weitzman & Fink, 1985); Nematobrycon Eigenmann and Grundulus Valenciennes (Mirande, 2010); and Coptobrycon Géry (Langeani & Serra, 2010 …”

A New Miniature Characid (Ostariophysi: Characiformes: Characidae), with Phylogenetic Position Inferred from Morphological and Molecular Data

“…However, among all the taxa with a single premaxillary tooth row, only Erythrocharax , Coptobrycon , Spintherobolus and the Cheirodontinae (except Prodontocharax ) present multicuspid, largely expanded, distally compressed teeth, whereas all other groups present conical or tricuspid cylindrical teeth. Erythrocharax can be distinguished from Coptobrycon by the absence of a longitudinal stripe onto the anal-fin base, and the presence of maxillary teeth (vs. longitudinal stripe present and maxillary teeth absent [23]), and from Spintherobolus by lacking the anteriormost proximal radial of the anal fin with an anteriorly extended lamina, and short caudal peduncle (vs. anteriormost proximal radial with anteriorly extended lamina and caudal peduncle extremely elongate). Although Erythrocharax has all the synapomorphic features listed by Malabarba [21] defining the Cheirodontinae, it is distinguished from all genera of that group with teeth bearing spatulated crowns by the presence of distinctly separate nostrils (vs. anterior and posterior nostrils overlapping, separated only by a skin fold).…”