Dicephaly (siamesetwins) in neonate Squalus acanthias (Elasmobranchii: Squaliniformes) South Coast of São Paulo – Brazil / Dicefalia em neonatos de Squalus acanthias (Elasmobranchii: Squaliniformes) encontrado no Litoral Sul de São Paulo - Brasil

Edris Queiroz Lopes, Luana Felix de Melo, Carlos Eduardo Malavasi Bruno, Renato Navilli, Alberto Ferreira de Amorim


Dicephalic individuals originate from a dualistic fusion, where the formation of two embryonic bodies occurs by a single blastoderm or by the joining of two distinct blastoderms of the same yolk. The morphometric data are expressed in percentages of total length-TL and were compared with others found in the literature. The dicephalous, newborn dogfish captured, was identified as Squalus acanthias, and was caught by a seabob-shrimp throw net, off the coast of Peruibe City e Itanhaém, São Paulo State, Brazil. The specimen was a male with 23.5 cm (right animal) and 22.8 cm (left animal) TL, and 800 g of total weight. Externally, the animal presented a lateral fusion and concerning the duplication of the head, they were separated until the fifth branchial arch. The exemplar presented: two pairs of first and second dorsal fins with spines; two pairs of pectoral fins; one pair of pelvic fins; one pair of claspers; and one caudal fin, with two superior lobes and one inferior lobe. The internal morphology displayed: two oral cavities; two esophagi; two stomachs (right stomach more developed); two livers (three lobules each); two hearts; one intestine; and one cloaca. The specimen can be considered the first record of dicephaly in S. acanthias.


Abnormal, shark, embryonic, diprosopus, captured dogfish, siamesetwins

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DOI: https://doi.org/10.34188/bjaerv3n3-110


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