Pairs Of Small Chromosomes Research Articles

Karyotype and molecular genetic differentiation of a 24-chromosomal form of the gray hamster <i>Nothocricetulus migratorius</i> from the Tien Shan

The widespread Palaearctic rodent species gray hamster Nothocricetulus migratorius has a karyotype with a stable number of chromosomes 2n = 22 throughout the entire range of its habitat. We found gray hamsters with diploid number of chromosomes 2n = 24 locally distributed in the Qurama Ridge of the Tyan Shan. A new karyotype and analysis of G- and NORs-bands of differentially stained chromosome sets were described for the first time. The described karyotype differs from the 22-chromosomal karyotype of gray hamsters by the Y-chromosome morphology and the presence of an additional pair of heteromorphic small chromosomes. Molecular genetic analysis revealed genetic divergence of 24- and 22-chromosomal forms of N. migratorius, and the differences between them in mitochondrial markers are comparable, and in nuclear markers exceed the differences between C. barabensis (2n = 20) and C. psevdogriseus (2n = 24). The data obtained give grounds to discuss the taxonomic status of the 24-chromosomal form of gray hamsters from the Qurama Ridge and consider the differentiation of N. migratorius karyomorphs as a stage of chromosomal speciation.

New cytogenetic data on Caryophyllaeus laticeps and Paracaryophyllaeus gotoi, parasites of evolutionary interest.

Caryophyllideans are intestinal parasites of freshwater fishes, occupying a basal position among the ‘true’ tapeworms. We performed detailed cytogenetic analyses of the well-known caryophyllidean species Caryophyllaeus laticeps. For comparison, we also examined for the first time the chromosomes of Paracaryophyllaeus gotoi, a specific parasite of loaches in China. Both species showed a diploid chromosome number of 2n = 20, n = 10m. Chromomycin A3 (CMA3)/diamidino-2-phenylindole (DAPI) staining performed for the first time in the class Cestoda revealed CMA3+/DAPI− bands in the pericentromeric regions of the short arms of chromosome pair no. 7 in the karyotype of C. laticeps. Fluorescence in situ hybridization with the 18S rDNA probe confirmed the presence of a single cluster of major rDNA near the centromere on a pair of small chromosomes in both species. These findings support the hypothesis that the ancestral state in the family Caryophyllaeidae is a single interstitial cluster of major rDNA genes and thus one nucleolar organizer region per haploid genome. Our results, which we presented together with literature data plotted on a phylogenetic tree, show stability of caryophyllidean karyotypes at the genus level, but showed differences between genera without a clear phylogenetic signal. The data allowed us to at least formulate a hypothesis about the ancestral haploid chromosome number of n = 10 for the family Caryophyllaeidae and possibly for the sister family Capingentidae. In addition, we compared two populations of C. laticeps from water bodies with different levels of polychlorinated biphenyl contamination, showing a slightly increased incidence of chromosomal abnormalities at the contaminated site.

Cytogenetics of Four Species of the Green Clade Aplastodiscus Lutz, 1950 (Anura: Cophomantinae): New Insights into the Chromosomal Evolution of the Genus

The tree frog Aplastodiscus is a Neotropical taxon that encompasses 15 species in the Atlantic forest biome, with one isolated species in the Central Brazilian Cerrado. To date, only 8 species have been karyotyped, showing high levels of diploid number variation, which allowed clustering species in chromosome number groups: 2n = 24 (Aplastodiscus perviridis group), 2n = 22 (Aplastodiscus albofrenatus group), 2n = 20, and 2n = 18 (both within Aplastodiscus albosignatus group). This study aims to report karyotypic information on 4 species from the last 2 groups using classical and molecular cytogenetic techniques and hypothesize chromosomal evolutionary trends within the species groups. Aplastodiscus weygoldti showed 2n = 22; Ag-NOR and FISH 18S rDNA signals were located in the interstitial region of the short arms of chromosome pair 6. Aplastodiscus cavicola, Aplastodiscus sp. 4, and Aplastodiscus sp. 6 showed 2n = 18; Ag-NOR and FISH 18S rDNA bands were located in the terminal region of the long arm of chromosome pair 9. Our results support multiple and independent chromosome fusion events within Aplastodiscus, including a new chromosome fission event. Ag-NOR and FISH 18S rDNA patterns were restricted to the small chromosome pairs, similar to the other species within this genus, and confirm overall chromosome morphology conservation among the genera of Cophomantinae.

Evolutionary insights in Amazonian turtles (Testudines, Podocnemididae): co-location of 5S rDNA and U2 snRNA and wide distribution of Tc1/Mariner.

ABSTRACTEukaryotic genomes exhibit substantial accumulation of repetitive DNA sequences. These sequences can participate in chromosomal reorganization events and undergo molecular cooption to interfere with the function and evolution of genomes. In turtles, repetitive DNA sequences appear to be accumulated at probable break points and may participate in events such as non-homologous recombination and chromosomal rearrangements. In this study, repeated sequences of 5S rDNA, U2 snRNA and Tc1/Mariner transposons were amplified from the genomes of the turtles, Podocnemis expansa and Podocnemis unifilis, and mapped by fluorescence in situ hybridization. Our data confirm the 2n=28 chromosomes for these species (the second lowest 2n in the order Testudines). We observe high conservation of the co-located 5S rDNA and U2 snRNA genes on a small chromosome pair (pair 13), and surmise that this represents the ancestral condition. Our analysis reveals a wide distribution of the Tc1/Mariner transposons and we discuss how the mobility of these transposons can act on karyotypic reorganization events (contributing to the 2n decrease of those species). Our data add new information for the order Testudines and provide important insights into the dynamics and organization of these sequences in the chelonian genomes.

Chromosome studies on freshwater prawn, Macrobrachium lanchesteri (Decapoda, Palaemonidae) from Thailand

The chromosomes of freshwater prawn (Macrobrachium lanchesteri) were characterized by means of conventional Giemsa-, DAPI-, silver-staining and G-banding techniques. The number of diploid chromosome and fundamental number were 2n = 116 and 226, respectively. The karyotype consisted of 54 metacentric, 46 submetacentric, 10 acrocentric and 6 telocentric chromosome pairs. The karyotype formula could be deduced as 2n (116) = L 24 m + L 8 a + M 12 m + M 6 sm + M 2 a + S 18 m + S 40 sm + S 6 t . Heterochromatic regions were located in the centromere and pericentromeric regions of most chromosomes, and NORs were found on two pairs of small chromosomes. G-band karyotype of M. lanchesteri was provided for the first time.

Karyological Investigation of <i>Bufo variabilis</i> (Anura: Bufonidae) Populations from Northwest and Southeast of Iran

The cytogenetic data of Bufo variabilis populations in northwest and southeast of Iran are rare, so, it is highly important to describe the karyotypic details of unexamined populations of variable toads from these regions. In this study, karyotype characteristics of seventeen specimens of B. variabilis were examined. Karyotypes consist of 2 n = 22 chromosomes and could be arranged into two categories; the first group has 6 pairs of large chromosomes and the second one has 5 pairs of small chromosomes. These chromosomes are metacentric or submetacentric. Karyotypes of B. variabilis from northwest of Iran showed that 4 th and 7 th pairs of chromosomes are submetacentric while in variable toads from southeastern 4 th and 9 th pairs of chromosomes are submetacentric. Neither sexual heteromorphism, nor secondary constriction was observed in any pairs of chromosomes.

Chromosome evolution in Cophomantini (Amphibia, Anura, Hylinae).

The hylid tribe Cophomantini is a diverse clade of Neotropical treefrogs composed of the genera Aplastodiscus, Boana, Bokermannohyla, Hyloscirtus, and Myersiohyla. The phylogenetic relationships of Cophomantini have been comprehensively reviewed in the literature, providing a suitable framework for the study of chromosome evolution. Employing different banding techniques, we studied the chromosomes of 25 species of Boana and 3 of Hyloscirtus; thus providing, for the first time, data for Hyloscirtus and for 15 species of Boana. Most species showed karyotypes with 2n = 2x = 24 chromosomes; some species of the B. albopunctata group have 2n = 2x = 22, and H. alytolylax has 2n = 2x = 20. Karyotypes are all bi-armed in most species presented, with the exception of H. larinopygion (FN = 46) and H. alytolylax (FN = 38), with karyotypes that have a single pair of small telocentric chromosomes. In most species of Boana, NORs are observed in a single pair of chromosomes, mostly in the small chromosomes, although in some species of the B. albopunctata, B. pulchella, and B. semilineata groups, this marker occurs on the larger pairs 8, 1, and 7, respectively. In Hyloscirtus, NOR position differs in the three studied species: H. alytolylax (4p), H. palmeri (4q), and H. larinopygion (1p). Heterochromatin is a variable marker that could provide valuable evidence, but it would be necesserary to understand the molecular composition of the C-bands that are observed in different species in order to test its putative homology. In H. alytolylax, a centromeric DAPI+ band was observed on one homologue of chromosome pair 2. The band was present in males but absent in females, providing evidence for an XX/XY sex determining system in this species. We review and discuss the importance of the different chromosome markers (NOR position, C-bands, and DAPI/CMA3 patterns) for their impact on the taxonomy and karyotype evolution in Cophomantini.

Chromosome Evolution in the Free-Living Flatworms: First Evidence of Intrachromosomal Rearrangements in Karyotype Evolution of Macrostomum lignano (Platyhelminthes, Macrostomida).

The free-living flatworm Macrostomum lignano is a hidden tetraploid. Its genome was formed by a recent whole genome duplication followed by chromosome fusions. Its karyotype (2n = 8) consists of a pair of large chromosomes (MLI1), which contain regions of all other chromosomes, and three pairs of small metacentric chromosomes. Comparison of MLI1 with metacentrics was performed by painting with microdissected DNA probes and fluorescent in situ hybridization of unique DNA fragments. Regions of MLI1 homologous to small metacentrics appeared to be contiguous. Besides the loss of DNA repeat clusters (pericentromeric and telomeric repeats and the 5S rDNA cluster) from MLI1, the difference between small metacentrics MLI2 and MLI4 and regions homologous to them in MLI1 were revealed. Abnormal karyotypes found in the inbred DV1/10 subline were analyzed, and structurally rearranged chromosomes were described with the painting technique, suggesting the mechanism of their origin. The revealed chromosomal rearrangements generate additional diversity, opening the way toward massive loss of duplicated genes from a duplicated genome. Our findings suggest that the karyotype of M. lignano is in the early stage of genome diploidization after whole genome duplication, and further studies on M. lignano and closely related species can address many questions about karyotype evolution in animals.

Demonstration of 5-Methylcytosine-Rich DNA Sequences in Chiroptera

5-Methylcytosine-rich heterochromatic regions were demonstrated in metaphase chromosomes of 5 species of Chiroptera by indirect immunofluorescence using a monoclonal anti-5-methylcytosine antibody. These species belong to 4 genera and 2 families and are characterized by divergent karyotypes. One species (Glauconycteris beatrix) has an extremely low diploid chromosome number of 2n = 22 with only meta- to submetacentric elements and remarkably large amounts of constitutive heterochromatin located in the centromeric and pericentromeric regions of all chromosome pairs. Two species (G. beatrix and Neoromicia cf. guineensis) possess X-autosome translocations. In all species, the hypermethylated chromosome segments correspond to constitutive heterochromatin, and the numbers and positions of hypermethylated chromosome segments in the karyotypes are constant and species-specific. In some species (Pipistrellus hesperidus, Neoromicia cf. somalicus), there are several smaller chromosome pairs in which the bright anti-5-methylcytosine antibody labeling is not restricted to constitutively heterochromatic regions but is observed along the whole lengths of these chromosomes. The nature of these additional hypermethylated regions is discussed. The analysis of 5-methylcytosine-rich chromosome regions elucidates valuable data for chiropteran cytogenetics and reflects the high pace of evolution of the repetitive DNA fraction in their genomes.

The karyotype of the great sculpin, Myoxocephalus polyacanthocephalus (Pallas, 1814) (Pisces: Cottidae), from the Russian part of the species range

The karyotype of the great sculpin, Myoxocephalus polyacanthocephalus (Pallas, 1814) (Pisces: Cottidae) from the Sea of Okhotsk and the Sea of Japan has been studied for the first time. The karyotype is stable; it consists of 40 chromosomes (4 metacentric, 2 submeta-subtelocentric, 20 subtelocentric, and 14 acrocentric chromosomes); the number of chromosomal arms is 44 + 2. Nucleolar organizer regions (NOR) are found in the telomeric region of the arm in one homologue of a pair of small metacentric chromosomes, using the Ag-NOR banding technique. A comparative analysis of the karyotype of M. polyacanthocephalus and the karyotypes of other Myoxocephalus species (M. stelleri, M. brandtii, M. jaok, M. ochotensis, and M. scorpius) has been carried out based on the main karyotype characters, as well as on the number and localization of NORs. The identified differences make it possible to differentiate the studied species, whereas the general traits indicate their taxonomic proximity.

Evidence for Karyotype Polymorphism in the Free-Living Flatworm, Macrostomum lignano, a Model Organism for Evolutionary and Developmental Biology.

Over the past decade, the free-living flatworm Macrostomum lignano has been successfully used in many areas of biology, including embryology, stem cells, sexual selection, bioadhesion and aging. The increased use of this powerful laboratory model, including the establishment of genomic resources and tools, makes it essential to have a detailed description of the chromosome organization of this species, previously suggested to have a karyotype with 2n = 8 and one pair of large and three pairs of small metacentric chromosomes. We performed cytogenetic analyses for chromosomes of one commonly used inbred line of M. lignano (called DV1) and uncovered unexpected chromosome number variation in the form of aneuploidies of the largest chromosomes. These results prompted us to perform karyotypic studies in individual specimens of this and other lines of M. lignano reared under laboratory conditions, as well as in freshly field-collected specimens from different natural populations. Our analyses revealed a high frequency of aneuploids and in some cases other numerical and structural chromosome abnormalities in laboratory-reared lines of M. lignano, and some cases of aneuploidy were also found in freshly field-collected specimens. Moreover, karyological analyses were performed in specimens of three further species: Macrostomum sp. 8 (a close relative of M. lignano), M. spirale and M. hystrix. Macrostomum sp. 8 showed a karyotype that was similar to that of M. lignano, with tetrasomy for its largest chromosome being the most common karyotype, while the other two species showed a simpler karyotype that is more typical of the genus Macrostomum. These findings suggest that M. lignano and Macrostomum sp. 8 can be used as new models for studying processes of partial genome duplication in genome evolution.

Karyological characteristics of the Koh Tao caecilian, Ichthyophis kohtaoensis (Amphibia: Gymnophiona: Ichthyophiidae) by conventional staining and Ag-NOR banding techniques

The karyotypic analysis of the Koh Tao caecilian, Ichthyophis kohtaoensis Taylor, on 1960 from Surin Province, Thailand was obtained from the present study. Mitotic chromosome was prepared directly from the small intestine of specimens after in vivo colchicine treatment. The metaphase spreads were performed on microscopic slides and air-dried. Conventional staining, and Ag-NOR banding techniques were applied to stain the chromosome with Giemsa’s solution. Results showed that the number of diploid chromosome was 2n = 42, while the fundamental number (NF) was 64 in both males and females. The type of chromosomes included 6 large metacentric, 2 large submetacentric, 12 small metacentric, 2 small submetacentric, and 20 small telocentric chromosomes. We found that nucleolar organizer regions/NORs (the representative of chromosome marker) were located on the small telocentric chromosome pair 19. No cytologically distinguishable sex chromosome was observed. The karyotype formula is as follows: 2n (42) = L 6 m + L 2 sm + S 12 m + S 2 sm + S 20 t .

Cytotaxonomy of unionid freshwater mussels (Unionoida, Unionidae) from northeastern Thailand with description of a new species.

Morphological and chromosomal characteristics of a number of unionid freshwater mussels were studied from northeastern Thailand. Karyotypes of eight species from seven genera (Chamberlainia, Ensidens, Hyriopsis, Physunio, Pseudodon, Scabies and Trapezoideus) were examined. Six species possess 2n = 38 karyotypes, whereas Scabies crispata and an unidentified Scabies sp. lack three small chromosome pairs, giving a diploid number of 32. Moreover, the karyotypes of the unidentified Scabies differ from Scabies crispata as it exhibits a telocentric chromosome pair (6m + 7sm + 2st + 1t). Most of the conchological characters also differ between the two species – adult size, colour pattern, muscle scars, pseudocardinal and lateral teeth. The name Scabies songkramensis sp. n. is proposed for the unidentified species, and its description is included in this paper. Interestingly, seven species contain mostly bi-armed chromosomes, but only the mud-dweller in stagnant water, Ensidens ingallsianus, contains predominantly five telocentric pairs. In addition, the marker chromosome characteristics of an unbalanced long arm, twisted centromere, a wider angle 180° arrangement, a twisted arm and telomeric end union reported in this study are described for the first time for unionid mussels.

Comparative Cytogenetic Study in Four Alopiinae Door Snails (Gastropoda, Clausiliidae)

A cytogenetic study was carried out by means of standard and NOR-FISH staining methods on the chromosomes of four Alopiinae door snails, two species of the Delimini tribe (Siciliaria paestana and Papillifera bidens) and two species of Medorini tribe (Leucostigma candidescens and Medora sp.). The two Delimini species and Medora sp. showed similar karyotypes, concerning the number of chromosomes, 2n = 62, and the first metacentric pair of chromosomes clearly bigger than the other pairs, but differed in the number of the telocentric pairs: none in P. bidens, four in S. paestana and, even, 21 in Medora sp. Leucostigma candidescens had 2n = 48, all biarmed chromosomes. Loci of NORs were on a single medium small chromosome pair in all the four studied species. The obtained results evidence a relevant degree of intergeneric karyotypic diversity in Alopiinae, concerning both chromosome number and/or shape. The data allow us to make a hypothesis on the evolutionary chromosome trends for this door snail subfamily.

Systematics of the freshwater leech genus Hirudinaria Whitman, 1886 (Arhynchobdellida, Hirudinidae) from northeastern Thailand.

In total, 435 specimens of the Southeast Asian freshwater leech species within the Hirudinidae family were collected from 17 locations of various types of aquatic habitats in northeastern Thailand. They were all morphologically placed within the genus Hirudinaria Whitman, 1886 and there were three distinct species: the common Hirudinaria manillensis, 78.2% of all collected specimens and at all 17 locations, Hirudinaria javanica at 20.3% of collected samples and from five locations and a rarer unidentified morphospecies (Hirudinaria sp.) with six samples from only two locations. The karyotypes of these three species were examined across their range in this study area for 38, 11 and 6 adult specimens of Hirudinaria manillensis, Hirudinaria javanica and Hirudinaria sp., respectively. This revealed different chromosome numbers among all three species, with Hirudinaria javanica having n = 13, 2n = 26, Hirudinaria manillensis lacked one small chromosome pair with n = 12, 2n = 24, and the unknown Hirudinaria sp. differed from any known Hirudinaria karyotypes in exhibiting a higher chromosome number (n = 14, 2n = 28) and a gradual change in size from large to small chromosomes. This suggests that the unknown Hirudinaria sp. is a new biological species. However, phylogenetic analysis based upon a 658 bp fragment of the cytochrome oxidase subunit I gene placed this unknown morphospecies within the Hirudinaria manillensis clade, perhaps then suggesting a recent sympatric speciation, although this requires further confirmation. Regardless, the chromosomes of all three species were asymmetric, most with telocentric elements. A distinct bi-armed chromosome marker was present on the first chromosome pair in Hirudinaria javanica, whilst it was on pairs 1, 2, 3 and 5 in Hirudinaria manillensis, and on pairs 3 and 5 for the unknown Hirudinaria sp.

A cytogenetic, molecular genetic and morphological study of Patagonian chinchilla mice Euneomys (Rodentia, Cricetidae) in the Southern Central Andes

Euneomys is a genus of sigmodontine rodent endemic to South America, distributed along the Andes of Argentina and Chile and in adjoining Patagonian steppe. Here, we studied specimens of Euneomys from different localities in the Central Andes, Mendoza Province, Argentina. Karyotypic analyses confirm the presence of a new karyomorph of Euneomys chinchilloides, the form 2n = 34, FN = 62–64. This new karyomorph differs from the form E. chinchilloides with 2n = 36, FN = 64–66. The chromosome complement with 2n = 36 has an extra pair of small acro-telocentric chromosomes that is not present in individuals with 2n = 34. We also found small differences in molecular analyses with the mitochondrial COI gene. We recovered two monophyletic clades, one with specimens with 2n = 34 and the other one with specimens with 2n = 36, which are separated by a range of 0.7 to 1.2 % sequence divergence. Individuals from the two clades also show some morphological differences. Significant difference in the length of ear was found between the specimens with 2n = 34 and 36, and qualitative differences in the shape of the incisive foramen, the palate, and the palatine fossa were observed. The modification on fundamental and diploid number that we found between the two karyomorphs of E. chinchilloides can be the result of tandem chromosome fusion; such rearrangements are strongly negatively heterotic and lead to reproductive isolation between differentiated populations. Thus, the integrated cytogenetic, molecular, and morphologic analyses show concordant differentiation between the two karyomorph types of the uncommon E. chinchilloides from the Southern Central Andes of Argentina. The evidence presented here might reflect a recent and/or incipient allopatric speciation event. Further investigations are needed to elucidate the taxonomic and distributional status of species of Euneomys.

Physical mapping of 5S and 18S ribosomal DNA in three species of Agave (Asparagales, Asparagaceae)

Agave Linnaeus, 1753 is endemic of America and is considered one of the most important crops in Mexico due to its key role in the country’s economy. Cytogenetic analysis was carried out in Agave tequilana Weber, 1902 ‘Azul’, Agave cupreata Trelease et Berger, 1915 and Agave angustifolia Haworth, 1812. The analysis showed that in all species the diploid chromosome number was 2n = 60, with bimodal karyotypes composed of five pairs of large chromosomes and 25 pairs of small chromosomes. Furthermore, different karyotypical formulae as well as a secondary constriction in a large chromosome pair were found in all species. Fluorescent in situ hybridization (FISH) was used for physical mapping of 5S and 18S ribosomal DNA (rDNA). All species analyzed showed that 5S rDNA was located in both arms of a small chromosome pair, while 18S rDNA was associated with the secondary constriction of a large chromosome pair. Data of FISH analysis provides new information about the position and number of rDNA loci and helps for detection of hybrids in breeding programs as well as evolutionary studies.

Chromosomal Rearrangements Occurred Repeatedly and Independently during Species Diversification in Malagasy Geckos, GenusParoedura

We conducted a phylogenetic study through karyological data, by standard staining and Ag-NOR banding, and molecular analysis (by 12S and 16S mitochondrial rRNA genes and nuclear gene C-mos) on 11 species of Malagasy geckos, genus Paroedura, and two relatives (Ebenavia inunguis and Uroplatus phantasticus). Ebenavia inunguis and 17. phantasticus had 2n = 36 telocentric elements, NORs on the first chromosome pair in E. inunguis, and on the third chromosome pair in U. phantasticus. All examined Paroedura showed NORs on the smallest chromosome pair; moreover, six of the eleven examined species show a 2n = 36 karyotype, with a pair of metacentrics and 17 telocentric pair. The remaining species exhibited karyotypes with a diploid chromosome number ranging from 2n = 31 to 2n = 38. We assume that these karyotype assemblages derived from the 2n = 36 karyotype by cryptic and/or simple rearrangements, such as inversions, fissions and fusions. Furthermore, molecular and/or chromosomal data indicate that Paroedura is a monophyletic genus, in which chromosome rearrangements occurred repeatedly and independently during the specific diversification. Moreover both P. bastardi and P. gracilis in current definitions are paraphyletic assemblages of several related species, since their population proves more closely related to P. ibityensis or P. oviceps than co-specific populations. Key words: chromosome, Gekkonidae, Madagascar, Paroedura, molecular phylogeny.

Chromosomal rearrangements occurred repeatedly and independently during species diversification in Malagasy geckos, genus Paroedura

We conducted a phylogenetic study through karyological data, by standard staining and Ag-NOR banding, and molecular analysis (by 12S and 16S mitochondrial rRNA genes and nuclear gene C-mos) on 11 species of Malagasy geckos, genus Paroedura, and two relatives (Ebenavia inunguis and Uroplatus phantasticus). Ebenavia inunguis and U. phantasticus had 2n = 36 telocentric elements, NORs on the first chromosome pair in E. inunguis, and on the third chromosome pair in U. phantasticus. All examined Paroedura showed NORs on the smallest chromosome pair; moreover, six of the eleven examined species show a 2n = 36 karyotype, with a pair of metacentrics and 17 telocentric pair. The remaining species exhibited karyotypes with a diploid chromosome number ranging from 2n = 31 to 2n = 38. We assume that these karyotype assemblages derived from the 2n=36 karyotype by cryptic and/or simple rearrangements, such as inversions, fissions and fusions. Furthermore, molecular and/or chromosomal data indicate that Paroedura is a monophyletic genus, in which chromosome rearrangements occurred repeatedly and independently during the specific diversification. Moreover both P. bastardi and P. gracilis in current definitions are paraphyletic assemblages of several related species, since their population proves more closely related to P. ibityensis or P. oviceps than co-specific populations.

Karyological analysis of the shrimp Palaemon serratus (Decapoda: Palaemonidae)

Analysis of metaphases of Palaemon serratus (Pennant, 1777) revealed a diploid number of 2n=56 chromosomes with a karyotype composed of two large metacentric pairs, six subtelocentric pairs and twenty telocentric pairs. Four Ag-NORs and 45S rDNA signals were observed at the telomeres of two small telocentric chromosome pairs. Chromomycin A3 fluorochrome staining revealed GC-rich regions associated with Ag-NORs, and DAPI showed positive bright bands on centromeric or intercalary positions of subtelocentric and telocentric chromosomes.