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1.
BMC Evol Biol ; 19(1): 73, 2019 03 08.
Artigo em Inglês | MEDLINE | ID: mdl-30849933

RESUMO

BACKGROUND: Synbranchidae or swamp eels are fishes belonging to the order Synbranchiformes that occur in both freshwater and occasionally in brackish. They are worldwide distributed in tropical and subtropical rivers of four different continents. A large degree of chromosomal variation has been found in this family, mainly through the use of conventional cytogenetic investigations. Inside this group, a still almost unexplored species under the cytogenetic point of view is the Asian swamp eel Monopterus albus, a widely distributed species throughout Asia. Here, we tested the hypothesis of chromosomal speciation, where a case of sympatric speciation may occur as the primary consequence of chromosomal rearrangements. We performed a comparative chromosomal analysis of M. albus from 22 different localities in Thailand, using distinct staining methods (C-banding, Ag-NO3, and Chromomycin A3), and FISH with repetitive DNA probes (5S rDNA, 18S rDNA, Rex1 element and microsatellite repeats). RESULTS: This approach evidenced two contrasting karyotypes (named karyomorphs A and B) that varied concerning their 2n and repetitive DNAs distribution, where chromosomal fusions and pericentric inversions were involved in such differentiation. While the karyomorph A has 2n = 24 chromosomes, the karyomorph B has only 2n = 18, both with NF = 24. In addition, karyomorph A contains only acrocentric chromosomes, while karyomorph B contains three unique metacentric pairs. These features highlight that M. albus has already gone through a significant genomic divergence, and may include at least two cryptic species. CONCLUSIONS: This marked chromosomal differentiation, likely linked to the lifestyle of these fishes, point to the occurrence of a chromosomal speciation scenario, in which fusions and inversions had a prominent role. This highlights the biodiversity of M. albus and justifies its taxonomic revision, since this nominal species may constitute a species complex.


Assuntos
Evolução Biológica , Cromossomos/genética , Especiação Genética , Variação Genética , Cariótipo , Smegmamorpha/genética , Animais , Bandeamento Cromossômico , Mapeamento Cromossômico , Geografia , Metáfase/genética , Repetições de Microssatélites/genética , Tailândia
2.
Zootaxa ; 4362(2): 294-300, 2017 Dec 05.
Artigo em Inglês | MEDLINE | ID: mdl-29245432

RESUMO

Three new species of Ceraclea (Leptoceridae) from Southeast Asia are described and illustrated: Ceraclea (Athripsodina) trisdikooni n. sp. from Myanmar, C. (A.) thongnooi n. sp. from Thailand and Myanmar and C. (A.) thongpongi n. sp. from Laos. Ceraclea trisdikooni n. sp. is distinguished from other species by its inferior appendages recurved ventrad nearly 180° apically. The apex of the basal segment of each inferior appendage is more pointed. In ventral view, each inferior appendage of the new species has an obvious basoventral lobe with numerous long setae. Ceraclea thongnooi n. sp. is distinguished from those by inferior appendages that are each shaped like a seahorse head both in lateral view and ventral view. Ceraclea thongpongi n. sp. is distinguished from other species by the rectangular preanal appendages. In dorsal view, the apical end of segment X is oval and notched apically; in ventral view, the subapicodorsal lobe of each inferior appendage is rounded and straight.


Assuntos
Insetos , Animais , Laos , Mianmar , Tailândia
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