Karyological Data Research Articles

Karyological data of some plant species native to South Italy

Karyological data of some plant species native to South Italy

Divergent Chromosome Evolution in Hypostominae Tribes (Siluriformes: Loricariidae): Correlation of Chromosomal Data with Morphological and Molecular Phylogenies.

Hypostominae is the largest subfamily of Loricariidae, and is widely distributed throughout the Neotropic. In the present article, we analyze three Loricariidae species that were considered part of Hypostominae, from three different tribes, to discuss chromosome evolution in this fish group and to review the existent data for the subfamily. Rhinelepis aspera had 54 chromosomes (20m + 26sm+8st), whereas Pterygoplichthys ambrosettii and Megalancistrus parananus had 52 chromosomes, with 16m+24sm+8st+4a and 18m+24sm+10st, respectively. The karyological data were compared with existent phylogenetic hypotheses, indicating a common ancestor with 2n = 52 chromosomes for the Acanthicus, Hemiancistrus, and Peckoltia clades, as well as for Hypostomini. Shared recurrent characteristics of the tribes are discussed, as well as peculiarities of genera Ancistrus and Hypostomus. We propose that the occurrence of fragile sites demonstrated for Ancistrus facilitated chromosomal rearrangements that decreased the proportion of metacentric/submetacentric chromosomes and the diploid number in many species from this genus. Although Hypostominae is usually considered a subfamily with derived chromosome features, our revision shows that this is valid only for Hypostomini and Ancistrini, which have a divergent chromosome evolution from other tribes that seems to conserve plesiomorphic features.

Brassicales: an update on chromosomal evolution and ancient polyploidy

Brassicales comprise 17 families, c. 400 genera and more than 4600 species. Despite the mustard family (crucifers, Brassicaceae) continuing to be the subject of intensive research, the remaining 16 families are largely under studied. Here I summarize the available data on chromosome number and genome size variation across Brassicales in the context of a robust phylogenetic framework. This analysis has revealed extensive knowledge gaps in karyological data for non-crucifer and species-rich families in particular (i.e., Capparaceae, Cleomaceae, Resedaceae and Tropaeolaceae). A parsimonious interpretation of the combined chromosomal and phylogenetic data set suggests that the ancestral pre-Brassicales genome had 9 or 14 chromosome pairs, later multiplied by the At-β (beta) whole-genome duplication (WGD) to n = 18 or 28. This WGD was followed by post-polyploid diploidization marked by diversification to 12 or 13 families and independent decreases in chromosome numbers. Family-specific WGDs are proposed to precede the diversification of Capparaceae, Resedaceae and Tropaeolaceae.

Phylogeny and biogeography of Phyllomys (Rodentia: Echimyidae) reveal a new species from the Cerrado and suggest Miocene connections of the Amazon and Atlantic Forest

Phyllomys is the most species-rich genus among spiny tree rats of the family Echimyidae and includes members widely distributed throughout the Atlantic Forest of South America. Among recognized species recovered in previous studies, 4 lineages are unnamed and their taxonomic distinctness needs further investigation. Biogeographic analyses recovered an Amazonian ancestor of the basal lineage leading to living Phyllomys, suggesting ancient connections between the 2 largest South American rainforests, and presence of rainforest corridors within the central Brazilian dry biomes. Based on exhaustive taxonomic sampling of Phyllomys, applying multigene phylogenetic methods, and morphological and karyological data, we described a new species of Phyllomys from central Brazil. Geographical records from the center of the Cerrado biome of central Brazil indicate an unexpected location for the distribution of the genus, given the contrast between the physical and biological characteristics of the Cerrado and Atlantic Forest habitats. Contrary to previous studies, the analysis of the ancestral geographic range performed here suggests a Cerrado ancestral distribution for Phyllomys during the late Miocene. This result favors the hypothesis of a past link between the Amazon and Atlantic Forest in central Brazil, through the region occupied today by the dry Cerrado, and that forest expansions and contractions may have occurred in Brazilian dry biomes over the course of the Tertiary.

Tapeworm chromosomes: their value in systematics with instructions for cytogenetic study.

The history and value of cytogenetic features for addressing questions of the evolution and systematics of tapeworms (Cestoda) are briefly reviewed along with instructions for collecting karyological data. As a supplement to worm morphology, chromosome number and morphology have been helpful in determining the systematic status of some genera in the Diphyllobothriidae and species in the Bothriocephallidea. In addition, many new techniques for chromosome analysis have been recently applied in morphological and molecular studies of invertebrates, including tapeworms. Methods of molecular karyology, fluorescence in situ hybridisation, and chromosomal location of satellite DNA, microsatellites or histone genes may also provide useful data to inference of taxonomic relationships and for revealing trends or general lines of chromosome evolution. However, as karyological data are available only for few tapeworms, they are seldom an integral part of evolutionary and taxonomic studies of cestodes. A primary reason for this lack of karyological data may lie in general difficulties in working with tapeworm chromosomes. To address these problems, herein we present a well-tested, step-by-step illustrated guide on the fixation of tapeworm material and preparation of their chromosomes for cytogenetic studies. The technique requires standard glassware, few reagents and simple equipment such as needles; it can also be used on other neodermatan flatworms.

Phylogeny of the Inula group (Asteraceae: Inuleae): Evidence from nuclear and plastid genomes and a recircumscription of Pentanema

AbstractThe Inula complex (Asteraceae: Inulinae) is a monophyletic group which comprises eight genera distributed in Eurasia and Africa: Amblyocarpum, Carpesium, Chrysophthalmum, Inula, Pentanema, Rhanteriopsis, Telekia, and Varthemia. With the aim to shed light on the circumscription of these genera, phylogenetic analyses were performed with 293 new DNA sequences (ITS region from nrDNA and three plastid spacers from cpDNA: rps16–trnQ, rpl32–trnL, ndhF–rpl32). It is concluded that both Inula and Pentanema are paraphyletic and that generic delimitations within the Inula complex need to be revised. Based on the results of the analyses, together with morphological and karyological data, we argue that the best solution is a new circumscription of the genus Pentanema including an amended description and 24 new combinations of former Inula species. Resurrection of the names Codonocephalum, Monactinocephalus and Vicoa is proposed to preserve the monophyly of the genera included in the Inula complex. Incongruences between nrDNA and cpDNA are documented and discussed.

Cytogenetic Characterization of a Population of Acanthodactylus lineomaculatus Duméril and Bibron, 1839 (Reptilia, Lacertidae), from Southwestern Morocco and Insights into Sex Chromosome Evolution

Acanthodactylus lineomaculatus is now regarded as an ecotype of A. erythrurus with which it has been recently synonymized. Despite the wide range of A. erythrurus, karyological data for this species are scarce and limited to classical cytogenetic studies carried out in individuals from only 2 locations (central Spain and Spanish enclave of Melilla on the northwestern Mediterranean Moroccan coast). Here, for the first time, we cytogenetically characterized individuals of A. lineomaculatus from the southwestern Moroccan Atlantic coast with the aim to increase the karyological knowledge of this wide-ranging species and to assess if any chromosomal changes can be found in this ecotype in comparison to other populations of this species. The diploid number of the individuals investigated is 2n = 38 which is typical of most lacertids. Active NORs were located telomerically in a medium-small pair of chromosomes, and no inactive NORs were detected. C-banding revealed an intensely heterochromatic W chromosome composed of AT-rich (centromere and long arm telomeric region) and GC-rich (most of the long arm) regions, with extended interstitial telomeric sequences. These telomere-like repeats occupy the GC-rich heterochromatin of the W. The DNA composition of the W represents a trait distinguishing A. lineomaculatus (southwestern Morocco) from A. erythrurus from Spain that possess a DAPI-positive (AT-rich) W chromosome. In conclusion, these results add further evidence to the remarkable karyotype conservation in lacertid lizards, although differences in NOR location and in W chromosome structure among populations could suggest an incipient speciation mediated by chromosome changes in this wide-ranging lizard species.

Karyotypic and phylogeographic analyses of Cormura brevirostris (Chiroptera, Emballonuridae)

Cormura brevirostris is a rare and poorly known species of emballonurid bat that occurs in Central America and South America across the Amazonian region. Previous work showed that karyotypes of C. brevirostris from Colombia, Suriname, and the Brazilian Amazon presented 2n = 22 and FN = 40, although small differences in chromosome composition have been observed among these karyotypes. Phylogenetic studies using nuclear and mitochondrial markers also showed differences between Central and South American C. brevirostris individuals. We describe the karyotype of an adult male C. brevirostris from the Brazilian Amazon and compare it to other karyotypes reported for this species. We also investigate phylogenetic relationships within this species using 2 mitochondrial and 1 nuclear gene. Morphological characters and measurements of the Brazilian specimen matched those described for C. brevirostris. The karyotype displayed a C-banding pattern similar to those described for C. brevirostris from other localities. Phylogenetic analyses confirmed the monophyly of Cormura, but each marker showed a different relationship. Karyological data showing more than 1 lineage and deep intraspecific mitochondrial lineages suggest that this taxon could be a species complex, requiring additional taxonomic studies to elucidate species limits and phylogenetic relationships within the genus Cormura.

Recircumscription of Delphinium subg. Delphinium (Ranunculaceae) and implications for its biogeography

AbstractThe monophyly of Delphinium subg. Delphinium remains unresolved, owing to the controversial systematic position of the monotypic, eastern Asian endemic D. sect. Anthriscifolium. The other section of the subgenus, D. sect. Delphinium, is distributed in the Irano‐Turanian (IT) region extending westward to the Mediterranean Basin. Recently, a new genus endemic to Turkey, Pseudodelphinium, was described and considered related with Delphinium (Delphinieae) or Garidella (Nigelleae). In this study, we first conducted a broad phylogenetic analysis within Ranunculaceae using matK sequences and placed Pseudodelphinium in Delphinieae. We then performed a series of analyses using four molecular markers (trnK‐matK, trnS‐G, trnL‐F, ITS) focused on the tribe. The phylogenetic analyses based on the four‐marker dataset indicate that Pseudodelphinium is embedded within sect. Delphinium. The Swofford‐Olsen‐Waddell‐Hillis tests also reject the exclusion of Pseudodelphinium from Delphinium and sect. Delphinium. The monophyly of subg. Delphinium is not recognized because sect. Anthriscifolium unites with D. subg. Delphinastrum and Consolida. Based on molecular, morphological, and karyological data, we raise sect. Anthriscifolium to subgeneric status, whereas sect. Delphinium composed subg. Delphinium s.str. An integration of phylogenetic, molecular dating, and biogeographical methods indicates that the subgenus s.str. originated in East Asia during the latest Oligocene and began to diversify in the IT region at 8.45 Ma. Subsequently, the westward colonization events occurred at 7.06 Ma from the IT region to the Italian and Balkan Peninsulas and at 5.4 Ma from Italy to North Africa. A dispersal from North Africa to the Iberian Peninsula was inferred in the late Pliocene, supporting a hypothesis of trans‐sea dispersal. Within the Mediterranean Basin, climate aridification and eustatic sea‐level changes could have initiated the westward stepwise expansion of Delphinium.

The Taxonomic Status ofOligoryzomys mattogrossae(Allen 1916) (Rodentia: Cricetidae: Sigmodontinae), Reservoir of Anajatuba Hantavirus

Species of the cricetid genus Oligoryzomys are found across most Neotropical biomes, and several of them play important roles as natural reservoirs of hantaviruses and arenaviruses. Here we demonstrate that O. mattogrossae, previously considered a junior synonym of O. microtis, is a valid species, and that it is the oldest available name for specimens previously identified as O. fornesi from Brazil and northern Paraguay. Comparative morphology and phylogenetic analyses based on mitochondrial (cytochrome b) and nuclear (intron 7 of beta-fibrinogen) genes show that O. mattogrossae differs from its sister species O. microtis and from other forms of the genus, corroborating previously published karyological data. Oligoryzomys mattogrossae occurs in Cerrado and Caatinga habitats throughout central and northeastern Brazil and Paraguay, whereas distribution of O. fornesi is apparently restricted to southern Paraguay and northernmost Argentina. Specimens of O. mattogrossae were found to be the natural reservoir of the Anajatuba genotype of hantavirus in northeastern Brazil. Therefore, continuing efforts to delimit Oligoryzomys species and facilitate their identification are important for zoonotic monitoring.

Chromosome count and karyotype of two species of Clematis (Ranunculaceae)

Karyotype morphometric data of two species of the genus Clematis L., a cosmopolitan and diverse genus, were studied. Clematis flammula is a diploid with 2n = 16 chromosomes. It exhibits a gradual decrease in size of chromosomes from 14.83 (±3.6) µm to 7.58 (±3.65) µm. Its karyotype formula (2n = 2x = 16 = 10m + 6sm) differs from those of Clematis orientalis (2n = 4x = 32 = 18m + 8sm + 6st), which is in addition a tetraploid species. The intrachromosomal asymmetry (A1) indicates that C. flammula had the most symmetric karyotype A1 = 0.39 in comparison to C. orientalis (A1 = 0.96). The karyological data available in the literature for the genus have also been discussed against the backdrop of the present analysis. This is the first attempt to present the karyotype morphometric data for the tetraploid cytotype of C. orientalis from India.

A new giant egg-laying onychophoran (Peripatopsidae) reveals evolutionary and biogeographical aspects of Australian velvet worms

Representatives of Ooperipatellus (Peripatopsidae) are among the smallest onychophorans known, commonly varying between 10 and 20 mm in length. Herein, we present a peculiar new species of Ooperipatellus from Tasmania that can exceed twice the length of other representatives of this taxon. Ooperipatellus nickmayeri sp. nov. is comprehensively described based on morphological, molecular, karyological and slime protein profile data. Morphological analyses expose a set of novel features in this species, including a swollen area covered with a modified integument on the posterior border of the male genital pad, modified papillae on the female ovipositor and the presence of pseudoplicae in the dorsal integument. The evolutionary significance of pseudoplicae remains unclear, but similarities between O. nickmayeri sp. nov. and Plicatoperipatus jamaicensis, the only species from which these structures were previously known, suggest they evolved due to functional constraints of the onychophoran integument. Our karyological investigation further revealed that the new species has the largest karyotype known within Peripatopsidae (2n = 50, XY). Finally, the results of our molecular phylogenetic analyses support the recognition of O. nickmayeri sp. nov. and shed light on previously unclear aspects of the biogeographical history of Ooperipatellus in Southern Australia, Tasmania and New Zealand.

Microsatellite loci variation and investigation of gene flow between two karyoforms of Cricetulus barabensis sensu lato (Rodentia, Cricetidae)

We examine the diversity of six microsatellite loci and partial RAG1 exon of “barabensis” and “pseudogriseus” karyoforms in Cricetulus barabensis sensu lato species complex. A total of 435 specimens from 68 localities ranging from Altai to the Far East are investigated. The results of the population structure analysis (factor analysis and NJ tree based on Nei genetic distances) support subdivision into two well-differentiated clusters corresponding to the two karyoforms. These karyoforms are also well differentiated by the level of microsatellite variability. In several “barabensis” specimens, we found microsatellite alleles that are common in “pseudogriseus” populations but are otherwise absent in “barabensis.” Most of these specimens originate from a single population in one of the zones of potential contact between karyoforms, Kharkhorin in Central Mongolia. These molecular results are consistent with previously published karyological data in suggesting that rare hybridization events between the two chromosomal races occur in nature.

Speciation of Eversmann and Mongolian hamsters (Allocricetulus, Cricetinae): Experimental hybridization

Contrary to the pre-existing concepts based on morphological and karyological data on the impossibility of hybridization between hamster species of the genus Allocricetulus (A. curtatus and A. eversmanni), F1 hybrids in both combinations, and backcrosses, were obtained for the first time. Some restrictions of hybridization between females of A. eversmanni and males of A. curtatus were detected. Analysis of the synaptonemal complex in the hybrids produced by crossing a female of A. curtatus with a male of A. eversmanni demonstarted that a significant portion of the cells was subject to arrest and selection at the stage of meiosis prophase I. Nevertheless, some spermatocytes still generate viable spermatozoa. Thus, the possibility of hybridization in the laboratory between two Allocricetulus species with different numbers of chromosomes may testify to a relatively low divergence between them.

A NEW SPECIES OF CENTAUREA (ASTERACEAE) FROM TURKEY<br />

A new species of Centaurea (Asteraceae) from Turkey is described and illustrated. Centaurea nallihanense Uysal & Hamzaoğlu occurs on stony slopes of corrupted oak openings in the Province of Ankara in Central Anatolia. It seems to be similar to C. sect. Ptosimopappus but related to the Cheirolepis-Pseudoseridia complex. Diagnostic characters of similar taxa are provided and a comprehensive discussion is held on the basis of molecular and karyological data. The geographical distribution of the new species is mapped. The chromosome number of C. nallihanense, 2n = 2x = 18, counted in root tips, is also reported and illustrated. Its karyotype formula is 6m+3sm. The karyotype of C. nallihanense consists of mainly metacentric chromosomes with the length ranging from 1.113 to 1.771 µm, and the total haploid chromosome length of 12.909 µm. Also, the ITS gene region of the new species is amplified and sequenced to compare with the relatives and to identify the taxonomical position of the new species within Centaurea.

Morphological variability, chromosome polymorphism, and problems of identifying individual species of gobies of the group Ponticola (Gobiidae) and assessing taxonomic relations of local populations

In connection with the problems of identification of certain species of the genus Ponticola, and especially their juveniles, morphological and genetic studies of gobies collected in the northwestern part of the Black Sea basin were carried out using literature data and museum collections. Karyological data indicate a distinct species status of western (P. odessicus) and eastern (P. eurycephalus) mushroom gobies; the range of the latter includes not only the Sea of Azov but also waters of the Black Sea coast of the Crimean Peninsula; these conclusions are supported by preliminary molecular genetic studies. Based on the obtained results of intraspecific morphological variability of species, we propose morphological characteristics for identification of adult P. syrman and P. odessicus, as well as a specific set of characteristics to identify juvenile (body length less than 50 mm) P. syrman, P. kessleri, and P. odessicus. We reveal differences in the karyotype structure of P. syrman from populations of the Sasyk Lake and the Don River, which do not differ in terms of external morphological characteristics and variability of cytochrome b haplotypes. The need for further research of phylogeography and morphological and karyological variability of P. syrman sensu lato is assumed.

Cytogenetic data on six leafcutter ants of the genus Acromyrmex Mayr, 1865 (Hymenoptera, Formicidae, Myrmicinae): insights into chromosome evolution and taxonomic implications

Cytogenetic data for the genus Acromyrmex Mayr, 1865 are available, to date, for a few species from Brazil and Uruguay, which have uniform chromosome numbers (2n = 38). The recent cytogenetic data of Acromyrmex striatus (Roger, 1863), including its banding patterns, showed a distinct karyotype (2n = 22), similar to earlier studied Atta Fabricius, 1804 species. Karyological data are still scarce for the leafcutter ants and many gaps are still present for a proper understanding of this group. Therefore, this study aimed at increasing cytogenetic knowledge of the genus through the characterization of other six species: Acromyrmex balzani (Emery, 1890), Acromyrmex coronatus Fabricius, 1804, Acromyrmex disciger (Mayr, 1887), Acromyrmex echinatior (Forel, 1899), Acromyrmex niger (Smith, 1858) and Acromyrmex rugosus (Smith, 1858), all of which were collected in Minas Gerais – Brazil, except for Acromyrmex echinatior which was collected in Barro Colorado – Panama. The number and morphology of the chromosomes were studied and the following banding techniques were applied: C-banding, fluorochromes CMA3 and DAPI, as well as the detection of 45S rDNA using FISH technique. All the six species had the same chromosome number observed for already studied species, i.e. 2n = 38. Acromyrmex balzani had a different karyotype compared with other species mainly due to the first metacentric pair. The heterochromatin distribution also showed interspecific variation. Nevertheless, all the studied species had a pair of bands in the short arm of the first subtelocentric pair. The fluorochrome CMA3 visualized bands in the short arm of the first subtelocentric pair for all the six species, while Acromyrmex rugosus and Acromyrmex niger also demonstrated in the other chromosomes. The AT-rich regions with differential staining using DAPI were not observed. 45S ribosomal genes were identified by FISH in the short arm of the first subtelocentric pair in Acromyrmex coronatus, Acromyrmex disciger and Acromyrmex niger. The uniform chromosome number in the genus Acromyrmex (2n = 38) suggests that Acromyrmex striatus (2n = 22) should be transferred to a new genus. Other aspects of the chromosome evolution in ants are also discussed.

Carpological and receptacular morpho-anatomical characters of Inula, Dittrichia, Limbarda and Pulicaria species (Compositae, Inuleae): Taxonomic implications

Genus Inula L. is paraphyletic and heterogeneous with respect to several diverse characters, which makes delimiting taxa difficult. Dittrichia Greuter, Limbarda Adans. and Pulicaria Gaertn. were previously located in different sections within Inula, and subsequently segregated into separate genera. According to the latest molecular phylogenetic analyses based on plastid and nuclear DNA sequence data, supported by morphological and karyological data, it is suggested that type species of genus, Inula helenium L., should be separated from the remaining species to form a separate genus. The goals of this research are to (1) perform comparative micro-morphological and anatomical analysis of fruit and receptacle of species belonging to Inula, Pulicaria, Dittrichia and Limbarda genera in order to estimate their systematic value; (2) define further characters that would be useful in taxonomic delimitation of species that are often misidentified due to their morphological similarities; (3) investigate whether all these characters support the segregation of I. helenium into a separate genus. Using stereoscopic, light and scanning electron microscope, micro-morphological and anatomical characters of cypsela and receptacle were revealed. Cross sections of mature fruit were obtained using cryotechnic procedure. This study pertains to the evaluation of examined characters using correspondence analysis. The species’ characters, as well as those specific to the genera are identified and described. The findings reveal that the organisation of sclerenchyma tissue in a fruit and receptacle characteristics are features that tend to be diagnostic for genera. The results yielded by this study provide valuable criteria for delimitation of taxa belonging to Compositae tribe Inuleae, which are often misidentified due to their morphological similarities. Our results, based on anatomical and micro-morphological characteristics of the fruit and receptacle, also revealed that I. helenium can be distinguished as a separate taxon with equally small percentage of statistical support as Dittrichia, Limabarda and Pulicaria had.

Cryptic species of Ponto-Caspian bighead goby of the genus Ponticola (Gobiidae)

Based on karyological data, the validity of the species Ponticola iljini is re-established; its distribution is limited to the coast of the Mangyshlak Peninsula. The morphological characteristics and the basic color pattern of P. iljini are very similar to P. kessleri from the Black Sea basin and P. gorlap which inhabits the northern, western, and southern Caspian Sea. These three allopatric species have ctenoid scales to varying degrees on the crown and nape (100% presence in P. kessleri and complete absence in P. iljini), and there are small differences in the shape of the head, the thickness of the caudal peduncle, and in the form of otoliths; at the same time, they are clearly differentiated by the number of chromosomes and the presence of marker submetacentric chromosomes in P. iljini. In the phylogenetic tree based on the variation of the mitochondrial cytochrome b gene in the main species of Ponto-Caspian gobies, P. iljini, P. gorlap, and P. kessleri form independent phyletic lineages within a clade of the genus Ponticola. Redescription of the species P. iljini is provided; the possible causes of the identified intraspecific variation in the shape of the otoliths and temporal bounderies of the beginning of divergence of the considered three cryptic species, as well as isolating barriers that led to allopatric speciation, are discussed.

Karyotypes of four species of Xenodontini snakes (Serpentes) and implications for taxonomy

The karyotypes of four Xenodontini snake species, Lygophis dilepis, L. meridionalis, L. flavifrenatus and L. anomalus, are here described for the first time. We studied specimens from northeastern Argentina using conventional and silver (Ag-NOR) staining. While the typical ophidian karyotype is 2n = 36, we found that the karyotype of the studied species is 2n = 34, with metacentric and submetacentric chromosome pairs. The 4th NOR staining revealed that nucleolar organizer regions (NORs) are located on one pair of microchromosomes. In L. dilepis and L. anomalus the 4th chromosome pair is heteromorphic, and we suggest that it might be considered as the ZW sex chromosome pair. The optimization of available karyological data on a molecular phylogenetic tree of the tribe Xenodontini shows that the diploid numbers 2n = 28, 30 and 34 represent putative synapomorphy for Erythrolamprus, Xenodon and Lygophis, respectively. Our results provide new insights which fill gaps in our knowledge on the cytology in the genus Lygophis and identified a possible diagnostic character for the genus.