It is an autosomal dominant genetic disorderknown as a branchial arch syndrome affect first branchial arch
mainly affecting maxilla and mandible.
BAPX1 expression in the first branchial arch
marks a potential deleterious mechanism that can lead to oculo-auriculo-vertebral spectrum (25).
Other noteworthy features that further distinguish the new species from most Melanotaenia include the combination of 15-16 circumpeduncular scales and 18-20 total gill rakers on the first branchial arch
, both values that are relatively high for the genus compared to counts of 11-14 and 1318 respectively for most other species.
Arrest in the development of the first branchial arch
due to an insult to the neural crest cells has been suggested to be the cause of this malformation, which may be induced by chromosomal mutation or teratogens (4).
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 slightly deeper than wide, jaws slightly elongated, snout pointed, tip of anal fin slightly pointed in male, caudal fin rounded in male, pelvic-fin tip reaching anterior portion of anal-fin base in male, dorsal-fin origin on vertical between base of penultimate and last anal-fin ray, dorsal-fin rays 7-9, anal-fin rays 13-15, frontal squamation E or D-patterned, frontal scales arranged circularly, canal preopercular short and opened, contact organs on flank scales in male, longitudinal series of scales 40-45, gill rakers of first branchial arch
2 + 10, pink stripes on flank, jaws not distinctively pigmented, and round black spot on dorsal portion of caudal fin in female.
It results from failure of fusion of mandibular and maxillary processes of the first branchial arch
(1) and so Tessier cleft 7 is also associated with anomalies of the structures arising from first and second branchial arches.
(4-6) After fusion of the maxillary and mandibular processes, which are both derived from the first branchial arch
, the parotid duct takes its normal position inside the mouth at the level of the superior second molar.
Summary of soft anal rays, pectoral rays, and total gill rakers on the first branchial arch
for three species of Amphiprion.
Gill rakers small, the longest on first branchial arch
less than half length of longest gill filaments.
During the post-flexion stage, eight branchial spines are observed in the lower branch of the first branchial arch
, increasing during pre-juvenile development until 14 at the beginning of the juvenile stage.
7) eye; gill opening extending forward to below posterior margin of preopercle; caudal fin with two enlarged black spots, one each at upper and lower caudal fin base; tongue tip pointed or slightly rounded; pectoral rays 16-17; six short and stubby gill rakers on outer face of lower part of first branchial arch
; pelvic rays branched; third and fourth dorsal spines longer than other spines lb.