Hirschmann Alice; Fagundes Nelson J. R.; Malabarba, Luiz R.

Bryconamericus lethostigmus is the type-species of the monotypic genus Odontostoechus, diagnosed in part based on the presence of a unique tooth series in the premaxilla. Recently a new proposal of classification of the Stevardiinae placed Odontostoechus as a junior synonym of a monophyletic genus Bryconamericus sensu stricto, a genus characterized by the presence of two tooth series. Bryconamericus lethostigmus is redescribed herein and the single tooth series in the premaxilla is demonstrated to originate from merging of the external tooth row with the inner row during ontogeny refuting primary hypothesis of homology between the mouth morphology of B. lethostigmus and the genera Bryconacidnus, Ceratobranchia, Monotocheirodon, Othonocheirodus, Rhinopetitia and Rhinobrycon. A phylogeographic analysis indicated that the pattern described for the sympatric species Diapoma itaimbe is not mirrored by B. lethostigmus. The results also do not support the hypothesis of a new species in the rio Araranguá drainage.

Artigo: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1679-62252017000100212&lng=en&nrm=iso&tlng=en

Fig. 2 Bryconamericus lethostigmus. a. holotype, 48.68 mm SL (UMMZ 143272); b. color in life in a fresh collected specimen, rio Três Forquilhas basin, Itati, Rio Grande do Sul, Brazil, UFRGS 16500. 

Fig. 3 Bryconamericus lethostigmus. a. detail of the mouth of a small specimen, with teeth covered by the lips (UFRGS 16083, 24.5 mm SL); b. detail of the mouth of a large specimen with upper lip atrophied and showing the premaxillary teeth (UFRGS 20660, 54.3 mm SL). 

Fig. 5 Ontogenetic changes in the number of tooth rows of the premaxilla, number of teeth in the maxilla and shape of these bones in Bryconamericus lethostigmus. a. 24.1 mm SL (UFRGS 19488); b. 50.4 mm SL (MCP10774); c. 60.9 mm SL (MCP 19173). 

Tiago P. Carvalho,  Roberto E. Reis,   John P. Friel

A new miniature species of banjo catfish of the genus Hoplomyzon is described from the Lake Maracaibo Basin in Venezuela. The new species is distinguished from all its congeners by the straight anterior margin of the mesethmoid (vs. a medial notch); a smooth and straight ventral surface of the premaxilla (vs. presence of bony knobs on the ventral surface of premaxilla); absence of teeth on dentary (vs. teeth present on dentary); configuration of ventral vertebral processes anterior to anal fin, which are composed of single processes anterior to anal-fin pterygiophore (vs. paired process); presence of several filamentous barbel-like structures on the ventral surface of head of adults (vs. small papillous structures in the ventral surface of head of adults); and 8 anal-fin rays (vs. 6 or 7). An extensive osteological description is made of the holotype using high-resolution x-ray computed microtomography (HRXCT).

Artigo: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1679-62252017000100216&lng=en&nrm=iso&tlng=en

Fig. 1 Hoplomyzon cardosoi, holotype, MCNG 375, 18.5 mm SL, Caño La Raya, Zulia, Venezuela. Dorsal, left side lateral and ventral views.

Fig. 3 HRXCT model of skull and anterior body of Hoplomyzon cardosoi, MCNG 375, holotype, 18.5 mm SL. a. Dorsal view. b. Lateral view of left side. acf: anterior cranial fontanel; ang: anguloarticular; bp: basipterygium; br: branchiostegal rays; cl: cleithrum; cv: complex vertebrae; den: dentary; dfr: dorsal-fin rays; fr: frontal; hyo: hyomandibula; iop: interopercle; let: lateral ethmoid; mes: mesethmoid; met: metapterygoid; mnp: middle nuchal plate; mx: maxilla; na: nasal; pal: autopalatine; pcf: posterior cranial fontanel; pch: posterior ceratohyal; pfr: pectoral fin rays; pll: posterior lateral line plates; pmx: premaxilla; ps: pectoral-fin spine; pto: pterotic; qu: quadrate; sc: postemporo-supracleithrum; soc: parietal-supraoccipital; spo: sphenotic; io1: infraorbitals; iop: interopercle; infraorbital 1; sup: subpreopercle; pv5: parapophysis of vertebra 5; v6: vertebra 6; v9: vertebra 9; v11: vertebra 11; vdp11: vertebral dorsal process of vertebra 11; vfr: pelvic-fin rays. Scale bar = 1 mm. 

R. A. Silveira, J. Ferrer , F. G. Becker and S. M. Hartz

Biological invasion by species that are not naturally present in a native assemblage (nonnative species) is a multi-stage process (Blackburn et al., 2011). However, perception of an invasive process is difficult in early stages of the process, when abundance is very low and distribution is very limited. Understanding biological invasions and, eventually, taking management measures to prevent them, depends on early detection of the invasion process (Kolar and Lodge 2001). The presence of nonnative fish species has been reported in the Tramandaí river basin (Schifino et al., 2004; Artioli and Maia 2010; Artioli et al., 2013), but their introduction pathway in the Tramandaí river basin is unknown. A plausible possibility points to the artificial water channels in the wetlands and rice fields at the watershed divide between the Laguna dos Patos basin and the Tramandaí river basin. The aim of this paper is to report the occurrence of Pseudobunocephalus iheringii (Boulenger 1891) in an artificial channel in the watershed divide between the Laguna dos Patos basin and the Tramandaí river basin, in southern Brazil. This report represents the first record of an additional nonnative species in the Tramandaí basin, documents the early stage of a potential invasion process in this system, and represents the first evidence for the role of artificial water channels as invasion pathways for nonnative fish species into the Tramandaí basin, affecting two aquatic ecoregions (Laguna dos Patos and Tramandaí-Mampituba; Abell et al., 2008).

We argue that the absence of previous records in the Tramandaí river basin and the current establishment of artificial channels connecting the Laguna dos Patos and Tramandaí basin corroborate the hypothesis that this area may be the invasion pathway not only for P. iheringii, but probably for other previously recorded invasive species (Schifino et al., 2004; Artioli and Maia, 2010; Artioli et al., 2013). This inter-basin connection has been facilitated by local landscape characteristics, such as low terrain and large wetland areas, which allowed the development of rice fields and their associated network of artificial water channels (Becker et al., 2007), increasing the connectivity between two aquatic ecoregions (the Laguna dos Patos and Tramandaí-Mampituba).

Article: http://www.scielo.br/pdf/bjb/2017nahead/1519-6984-bjb-1519-698401716.pdf

Figure 1. (A) Map showing the sample unit where the three specimens of Pseudobunocephalus iheringii were collected; (B) The dorsal and ventral views of one individual of P. iheringii (UFRGS 20672, SL =30.94 mm).

Tiago P. Carvalho, Roberto E. Reis and Mark H. Sabaj

Xyliphius sofiae, new species, is described based on a unique specimen exhibiting four autapomorphies: eyes absent vs. present (though reduced); color pale, lacking pigment vs. head and body darkly pigmented; branchiostegal rays five vs. four; and unculiferous tubercles on posterior body distributed evenly vs. enlarged unculiferous tubercles typically arranged in five distinct rows above pelvic-fin base to posterior end of caudal peduncle. In addition, the pectoral fin of X. sofiae, new species, has one ossified proximal radial vs. two in congeners (except X. magdalenae, not examined). Xyliphius sofiae, new species, differs from all congeners except X. lepturus by snout tip elongated and narrowly rounded vs. short and broadly rounded, often with small median notch; fifth ceratobranchial relatively narrow with elongate acicular teeth vs. broadly expanded, leaf-shaped, with shorter and broader, conical teeth; anterior limits of branchial apertures separated by distance less than length of aperture vs. greater than length of aperture; anal-fin rays modally nine vs. seven; and lateral line extending onto base of caudal-fin rays vs. finishing in hypural region. Based on the single specimen collected in the main channel of the Río Amazonas near Iquitos, Peru, we describe the osteology of X. sofiae, new species, using a non-invasive technique: high-resolution X-ray computed tomography (HRXCT). We consider Xyliphius lombarderoi Risso and Risso, 1964, a species based on a unique holotype that is now lost, to be a subjective junior synonym of X. barbatus Alonso de Arámburu and Arámburu, 1962. Variable characteristics are summarized for the seven species of Xyliphius treated here as valid, and their distributions are plotted based on a comprehensive review of museum specimens.

Article: http://www.asihcopeiaonline.org/doi/abs/10.1643/CI-16-456

Holotype of Xyliphius sofiae, ANSP 182322, 44.1 mm SL, Rio Amazonas in vicinity of Iquitos, Loreto, Peru. (A–C) Alcohol preserved (scale bar =5 mm). (D) Live. Photos by M. Sabaj.