Diagnosis: Astyanax minor is distinguished from Iguacu Astyanax by combination of following characters: infraorbital 3 deep but not in contact with preopercle, leaving a narrow naked area between its border and preopercle; premaxillary external series with 4-6, usually 5 or 6 pentacuspid or heptacuspid teeth; first branchial arch
9-12, usually 10 rakers in upper branch and 13-16, usually 14 or 15 rakers in lower branch; a narrow and elongated vertical humeral bar.
Five new species of genus Astyanax Baird & Girard, 1854 from Rio Iguacu, Parana, Brazil (Ostariophysi, Characiformes, Characidae)/ Cinco novas especies do genero Astyanax Baird & Girard, 1854 do Rio Iguacu, Parana, Brasil (Ostariophysi, Characiformes, Characidae)
Distinguished from all other congeners by the combination of the following features: anterior portion of trunk wider than deep, jaws short, snout blunt, tip of anal fin rounded in male, caudal fin elliptical to acuminate in male, pelvic-fin tip not reaching to urogenital papilla in male, dorsal-fin origin posterior to anal-fin base, dorsal-fin rays 5-6, anal-fin rays 8-10, frontal squamation S-patterned, frontal scales arranged circularly, canal preopercular short and opened, contact organs absent, longitudinal series of scales 32-34, gill rakers of first branchial arch
1 + 7, dark brown oblique bars on flank, transverse black bar through the chin, and no black spot on dorsal portion of caudal fin.
Similarly, there is an apparent modal difference in the total number of gill rakers on the first branchial arch
and by the branchial spines in the inferior branch of the first branchial arch
(13 to 14 for D.
The embryologic migration pattern of the second branchial arch
tract originates in the tonsillar fossa, travels over third arch structures, and terminates in the middle to lower two-thirds of the lateral portion of the neck.
The orientation of teeth changes along these gill-raker tubercles, being curved towards the middle of the pharyngeal cavity in the upper part of the crown and directed at right angles to the surface of the branchial arch
closer to the base.
Mouth longer, upper jaw 2 reaching to below pupil; gill opening broader, extending forward to below middle or posterior part of pupil; caudal fin without enlarged black spots; tongue tip bilobed; pectoral rays 13-15; pelvic rays unbranched; second dorsal spine longest; 13-18 elongate and pointed gill rakers on outer face of lower part of first branchial arch
In the first branchial arch
the neural crest cells migrate towards the mandible, followed by their migration to the maxilla and lastly to the nasofrontal region.
Of these diverse anomalies, second branchial cleft lesions are the most common, accounting for approximately 95% of all branchial arch
Based on imaging and the clinical history a diagnosis of branchial fistula of fourth branchial arch
1) It occurs as the result of a developmental anomaly of the first branchial arch
, and it may be associated with other branchial cleft abnormalities.
It develops from 3rd branchial arch
and also receives contribution from the neural crest.