Species delimitation in the Acomys cahirinus-dimidiatus complex (Rodentia, Muridae) inferred from chromosomal and morphological analyses

Our earlier chromosome banding studies of Acomys cahirinus and Acomys dimidiatus (the latter long considered to be a subspecies of the former) revealed that, despite very close diploid numbers (36 vs. 38), these taxa possess sharply different karyotypes and undoubtedly belong to different species. In this context, the taxonomic status and the relationship between the two chromosomal forms in Sinai (2n = 36) and Israel (2n = 38), chromosomally homozygous across a vast range except for a very narrow hybrid zone, remain poorly documented. Neither of these forms have previously been studied by chromosome banding; thus, the exact nature of chromosomal differences as well as the species to which these forms should be assigned remain unknown. Here, we present the data on comparative G-banding analysis and morphometrics of Acomys from Israel, Sinai, and Saudi Arabia, and a hybrid obtained in laboratory crosses between latter two. The analysis revealed that karyotype of Acomys from Israel is identical to that of Acomys from Saudi Arabia and both are different from that of Acomys from Sinai by one Robertsonian fusion. Therefore, karyotypically, all three are very different from A. cahirinus. It follows from the study that Sinai and probably Arabian peninsula and Minor Asia must be excluded from geographical distribution of A. cahirinus, which is limited from West Sahara to Egypt along Nile river (except Sinai). Furthermore, the synthesis of chromosomal and recent molecular data suggests a phylogeographical scenario explaining the modern distribution of Acomys in the Sinai and Arabian peninsulas and permits the update of the taxonomic status of these populations

Species delimitation in the Acomys cahirinus - dimidiatus complex (Rodentia, Muridae) inferred from chromosomal and morphological analyses

Our earlier chromosome banding studies of Acomys cahirinus and A. dimidiatus (the latter long considered to be a subspecies of the former) revealed that despite very close diploid numbers (36 vs. 38), these taxa possess sharply different karyotypes and undoubtedly belong to different species. In this context, the taxonomic status and the relationship between the two chromosomal forms in Sinai (2n=36) and Israel (2n=38), chromosomally homozygous across a vast range except for a very narrow hybrid zone, remain poorly documented. Neither of these forms have previously been studied by chromosome banding, thus the exact nature of chromosomal differences as well as the species to which these forms should be assigned remain unknown. Here we present the data on comparative G-banding analysis and morphometrics of Acomys from Israel, from Sinai, from Saudi Arabia and a hybrid obtained in laboratory crosses between latter two. The analysis revealed that karyotype of Acomys from Israel is identical to that of Acomys from Saudi Arabia and both are different from that of Acomys from Sinai by one Robertsonian fusion. Therefore karyotypically all three are very different from A. c.. It follows from the study that Sinai and probably Arabian peninsula and Minor Asia must be excluded from geographical distribution of A. c., which is limited from West Sahara to Egypt along Nile river (except Sinai). Further, the synthesis of chromosomal and recent molecular data suggests a phylogeographic scenario explaining the modern distribution of Acomys in the Sinai and Arabian peninsulas and permits the update of the taxonomic status of these populations

Morphology and chromosomes of Tatera

In a sample of the genus Tatera Lataste 1882 from West Africa (Benin and Burkina Faso), we analyzed the cranial and dental morphology and the karyotype (G, R, C and NOR banding). The cranial morphology confirms the attribution of this sample to Tatera kempi Wroughton 1906. An analysis of the dental morphology was also performed but it seems not to offer diagnostic traits. The karyotype described in the present work for T. kempi is comparable with that described for T. hopkinsoni Thomas 1911, supporting the synonymy of these two taxa. In contrast, the karyological results clearly discriminate kempi from both guineae and nigrita, the latter currently considered a synonym. In the karyotype of T. kempi, we found a polymorphism of a small chromosome, which occurs in the three situations: metacentric/metacentric, metacentric/acrocentric and acrocentric/ acrocentric. A similar polymorphism was described for hopkinsoni. The banding shows that the variation of the morphology of the X chromosome in Tatera is related to a pericentric inversion. KEY WORDS: Tatera, rodents, chromosomes, taxonomy, West Africa, evolution