Chromosomal evolution in the South American Riodinidae (Lepidoptera: Papilionoidea)

We give the haploid chromosome numbers of 173 species or subspecies of Riodinidae as well as of 17 species or subspecies of neotropical Lycaenidae for comparison. The chromosome numbers of riodinids have thus far been very poorly known. We find that their range of variation extends from n =?9 to n =?110 but numbers above n =?31 are rare. While lepidopterans in general have stable chromosome numbers, or variation is limited at most a subfamily or genus, the entire family Riodinidae shows variation within genera, tribes and subfamilies with no single modal number. In particular, a stepwise pattern with chromosome numbers that are about even multiples is seen in several unrelated genera. We propose that this variation is attributable to the small population sizes, fragmented populations with little migration, and the behavior of these butterflies. Small and isolated riodinid populations would allow for inbreeding to take place. Newly arisen chromosomal variants could become fixed and contribute to reproductive isolation and speciation. In contrast to the riodinids, the neotropical Lycaenidae (Theclinae and Polyommatinae) conform to the modal n =?24 that characterizes the family.     

Chromosomes of sixteen European species ofLongitarsus flea-beetles (Coleoptera,Chrysomelidae)

Sixteen species ofLongitarsus have been chromosomally surveyed, showing a continuous range of even numbers from 2n=26 to 2n=32 chromosomes. Among the total of twenty-three known species, about 40% display a 14+Xy male karyotypic formula, the possible modal and most primitive one for the genus. The current taxonomy of species groupings is in good agreement with the chromosome numbers in some cases, but not in others. Also, there is no interrelationship between chromosome numbers and foodplant selection. The number of large bivalents at metaphase I is generally negatively correlated with the diploid value, suggesting the possible role of centric fusions coupled to shifts in the amount of chromatin as the main chromosomal changes in the evolution ofLongitarsus. The karyotypes of a few studied species are composed of metacentric chromosomes, some of them of rather large size, and a minute y-chromosome. A possible example of polymorphism for the chromosome number inL. nigrofasciatus is reported and briefly discussed.     

X chromosomes of American marsupials contain minimal amounts of euchromatin

The karyotypes of four South American didelphid marsupials, representing diploid numbers of 2n = 14 and 18, have been analyzed by a variety of banding techniques. The 2n = 14 karyotypes display a high degree of homoeology, but there also exist distinct similarities between the 2n = 14 and 2n = 18 karyotypes. The interspecific differences found are due to centric fissions, pericentric inversions, and variations in the amount and composition of the constitutive heterochromatin. Contrary to the evolutionary conservation of the banding patterns in all autosomal arms, there are multiple differences in the number and chromosomal location of the nucleolus organizer regions. In species with X-linked nucleolus organizers, the 18S + 28S ribosomal RNA genes escape inactivation in female cells. Measurements on the X chromosomes of Marmosa fuscata and Micoureus demerarae unexpectedly reveal the lowest quantities of euchromatin so far determined in the X chromosomes of mammals: 1.5% and 1.8%, respectively, of their haploid female genomes. This is significantly less than the amount of euchromatin in the basic X chromosomes of other marsupials (3%) or eutherians (5%).     

Chromosome evolution in Neotropical Danainae and Ithomiinae (Lepidoptera)

Chromosome numbers are given for 1011 populations of 242 species, representing the full range of taxa (49 of the about 52 presently recognized genera) in the Neotropical Nymphalid butterfly subfamily Ithomiinae (prime movers for mimicry rings), including many additional geographical subspecies from 47 regions from Mexico and the Caribbean islands throughout all tropical South American countries to southern Brazil. Twelve Neotropical Danainae (in 3 genera), all but one with n=29-31, and the Australian Tellervo (n=32) served as sister groups for comparison. The numbers range near-continuously from n=5 to n=120 with modal values (33-84 counts) at n=12-18, and only 16 and 26 counts at the usual modal number of all butterfly groups, n=30-31. Superimposition of these changes in karyotype on a cladistic phylogeny of the subfamily indicates possible early halving of the complement to n about 14-15, followed by much variation in each genus and tribe. While at least 17 species in 15 genera show stable karyotypes over much of the Neotropics, at least 40 species show large geographical variation in number of chromosomes, rarely accompanied by any evidence for reduction in fertility or incipient speciation. The evolutionary opportunism of the members of this subfamily probably accompanies their known population biology and community ecology: they are common, shade-loving, highly gregarious (occurring in small multispecies "pockets" in deep forest) and often migratory as a community when the environment becomes unfavorable (too hot or dry).     

POLYPLOIDY,DYSPLOIDY, AND CHROMOSOME PAIRING IN ECHEVERIA (CRASSULACEAE) AND ITS HYBRIDS

The 140+ species of Echeveria have more than 50 gametic chromosome numbers, including every number from 12 through 34 and polyploids to n = ca. 260. With related genera, they comprise an immense comparium of 200+ species that have been interconnected in cultivation by hybrids. Some species with as many as 34 gametic chromosomes include none that can pair with each other, indicating that they are effectively diploid, but other species with fewer chromosomes test as tetraploids. Most diploid hybrids form multivalents, indicating that many translocations have rearranged segments of the chromosomes. Small, nonessential chromosomal remnants can be lost, lowering the number and suggesting that higher diploid numbers (n = 30–34) in the long dysploid series are older. These same numbers are basic to most other genera in the comparium (Pachyphytum, Graptopetalum, Sedum section Pachysedum), and many diploid intergeneric hybrids show very substantial chromosome pairing. Most polyploid hybrids here are fertile, even where the parents belong to different genera and have very different chromosome numbers. This seems possible only if corresponding chromosomes from a polyploid parent pair with each other preferentially, strong evidence for autopolyploidy. High diploid numbers here may represent old polyploids that have become diploidized by loss, mutation, or suppression of duplicate genes, but other evidence for this is lacking. Most species occur as small populations in unstable habitats in an area with a history of many rapid climatic and geological changes, presenting a model for rapid evolution.     

Phylogenetic analysis of G-banded karyotypes among the South American subterranean rodents of the genus Ctenomys (Caviomorpha: Octodontidae), with special reference to chromosomal evolution and speciation

The chromosomes of subterranean rodents of the South American genus Ctenomys are highly variable with diploid numbers ranging from 10 to 70. The phylogenetic relationships of this group have been analysed cladistically using G-banded karyotypes as have the chromosomal rearrangements involved in its karyotypic differentiation. One group, called the 'Corrientes group', has very variable chromosomes but low allozymic and morphological differentiation among its members. This group has been analysed with respect to chromosomal speciation. Using a member of another subfamily (Octodontomys gliroides) as an outgroup, the results indicate that karyotypes with low diploid and fundamental numbers are plesiomorphic. The range of diploid numbers studied here is between 22 and 70, while the fundamental numbers are between 40 and 86. It was found that the main chromosomal rearrangement that transforms karyotypes towards higher diploid and fundamental numbers is the acquisition of new chromosomal material via unknown mechanisms, followed by pericentric inversions that generate new chromosomal arms, centric fusions and centric fissions. In spite of their low differentiation regarding allozymic and morphological features, it was found that the karyomorphs of the Corrientes group have enough chromosomal differentiation to consider them as distinct species. Beside the range of diploid and fundamental numbers of this group (42–70 and 80–84 respectively), their pairwise chromosomal differences are high. The most closely related of them differ in one nonhomologous arm, one Robertsonian change and a whole chromosome duplication. The most differentiated taxa differ in 20 arms with lack of homology, 12 Robertsonian changes (one with monobrachial homology), six pericentric inversions and the above mentioned probable arm duplication. For these reasons, it is probable that some kind of chromosomal speciation has occurred in the Corrientes group.     

Chromosome numbers in antlions (Myrmeleontidae) and owlflies (Ascalaphidae) (Insecta,Neuroptera)

A short review of main cytogenetic features of insects belonging to the sister neuropteran families Myrmeleontidae (antlions) and Ascalaphidae (owlflies) is presented, with a particular focus on their chromosome numbers and sex chromosome systems. Diploid male chromosome numbers are listed for 37 species, 21 genera from 9 subfamilies of the antlions as well as for seven species and five genera of the owlfly subfamily Ascalaphinae. The list includes data on five species whose karyotypes were studied in the present work. It is shown here that antlions and owlflies share a simple sex chromosome system XY/XX; a similar range of chromosome numbers, 2n = 14-26 and 2n = 18-22 respectively; and a peculiar distant pairing of sex chromosomes in male meiosis. Usually the karyotype is particularly stable within a genus but there are some exceptions in both families (in the genera Palpares and Libelloides respectively). The Myrmeleontidae and Ascalaphidae differ in their modal chromosome numbers. Most antlions exhibit 2n = 14 and 16, and Palparinae are the only subfamily characterized by higher numbers, 2n = 22, 24, and 26. The higher numbers, 2n = 20 and 22, are also found in owlflies. Since the Palparinae represent a basal phylogenetic lineage of the Myrmeleontidae, it is hypothesized that higher chromosome numbers are ancestral for antlions and were inherited from the common ancestor of Myrmeleontidae + Ascalaphidae. They were preserved in the Palparinae (Myrmeleontidae), but changed via chromosomal fusions toward lower numbers in other subfamilies.     

Variation and Evolution of Karyotype Characters in Palm Subfamily Coryphoideae s.l.

Karyological data are presented for 13 genera of palm subfamily Coryphoideae s.l. Chromosome numbers of 4 species and of genus Guihaia (G. argyrata, 2n = 36) are new. Apart from the prevailing chromosome number of 2n = 36, subfam. Coryphoideae s.l. shows extreme heterogeneity with respect to chromosome size and morphology, organization of constitutive heterochromatin (C-banding, fluorochrome staining), interphase nucleus structures and prophase condensation patterns. Five karyologically differing groups of genera can be distinguished (Coccothrinax-group, Guihaia, Livistona-group incl. Sabal, Phoenix, and Bismarckia). Chromosome evolution probably has gone from medium sized to very small chromosomes with an average length of less than 1.5 μm; hc-distribution from evenly distributed throughout the karyotype to accumulated in few chromosomes; from simple banding patterns to complicated ones (hc-elaboration). Karyotypes with chromosomes of continuously decreasing size, similar morphology, and uniform prophase condensation probably gave rise to almost bimodal karyotypes with non-uniform, heteropycnotic chromosomal structures. Changes in the organization of interphase nuclei are corresponding. Karyotype differentiation is compared to major evolutionary events in floral and vegetative morphology of subfam. Coryphoideae s.l. Karyologically, genera Phoenix and Bismarckia are isolated and the relations to the remaining part of the subfamily are not clear.     

Evolution of chromosome number in mealybugs (Pseudococcidae: Homoptera)

Chromosome numbers of over 90 species of mealybugs are presented (71 for the first time). The diploid chromosome number (2n) ranged from 8 to 64, but over 68% of the species had 2n=10, and 10 is considered to represent the ancestral 2n in this family. Since only 4 species had 2n<10,and 26 had 2n>10, it is concluded that in this family increases in 2n occurred much more often than decreases. The data are compared to those from two other coccid families, the Diaspididae and the Eriococcidae. Unexpectedly, in both the Pseudococcidae and the Diaspididae the frequency of species with the modal 2n is lowest among species from monotypic genera and from genera from which only a single species was examined, and increases with the increase in the number of species examined per genus.(died June 10, 1977)     

Chromosome evolution in the Salmonidae (Pisces): an update

The karyotypes of salmonid fishes including taxa in the three subfamilies Coregoninae, Thymallinae and Salmoninae are described. This review is an update of the (Hartley, 1987) review of the chromosomes of salmonid fishes. As described in the previous review, the karyotypes of salmonid fishes fall into two main categories based on chromosome numbers: the type A karyotypes have diploid numbers close to 80 with approximately 100 chromosome arms (2n = 80, NF = 100), and the type B karyotypes have diploid numbers close to 60 with approximately 100 chromosome arms (2n = 60, NF = 100). In this paper we have proposed additional sub categories based on variation in the number of chromosome arms: the A' type with NF = 110-120, the A" type with NF greater than 140, and the B' type with NF less than 80. Two modes of chromosome evolution are found in the salmonids: in the Coregoninae and the Salmoninae the chromosomes have evolved by centric fusions of the Robertsonian type decreasing chromosome numbers (2n) while retaining chromosome arm numbers (NF) close to that found in the hypothetical tetraploid ancestor so that most extant taxa have either type A or type B karyotypes. In the Thymallinae, the chromosomes have evolved by inversions so that chromosome arm numbers (NF) have increased but chromosome numbers (2n) close to the karyotype of the hypothetical tetraploid ancestor have been retained and all taxa have type A' karyotypes. Most of the taxa with type B karyotypes in the Coregoninae and Salmoninae are members of the genus Oncorhynchus, although at least one example of type B karyotypes is found in all of the other genera. These taxa either have an anadromous life history or are found in specialized lacustrine environments. Selection for increases or decreases in genetic recombination as proposed by Qumsiyeh, 1994 could have been involved in the evolution of chromosome number in salmonid fishes.     

Study on the inheritance of the centric fusion in the blue fox,Alopex lagopus

The inheritance of a centric fusion in the blue fox,Alopex lagopus was investigated in 38 litters (258 animals) originated from matings of parents (64 animals) with all possible diploid numbers of chromosomes (2n=50, 49 and 48). In general, the Robertsonian translocation was inherited in accordance with the Mendelian principle. However, in the matings of females with 2n=49 and males with 2n=50 a significantly higher number of animals with 2n=50 was observed in the progeny. Moreover, observations on two litters indicated thede novo occurrence of the centric fusion and fission.     

Karyological and taxonomic notes on Ophrys (Orchidoideae, Orchidaceae) from the Iberian Peninsula

Karyological information on Iberian Ophrys species is very limited. This paper provides the haploid and diploid chromosome numbers of 11 taxa of sect. Pseudophrys and sect. Ophrys , both of which are well represented in the Iberian Peninsula, and two taxa from Tunisia. The first data on chromosome numbers for O. vasconica (2 n  = 72, 74), O. ficalhoana (2 n  = 36), O. picta (2 n  = 36), O. sphegifera ( n  = 18, 2 n  = 36, 38) and O. passionis (2 n  = 36) are also presented, confirming the stability of the chromosome number in Ophrys . In addition, populations of the group O. omegaifera ( O. dyris and O. vasconica ), together with tetraploidy, pentaploidy and the existence of aneuploid phenomena, are reported for the first time in Iberia. The basic diploid number is always 2 n  = 36. The karyotypes of several species were analysed. Evolutionary trends in Ophrys chromosomes are discussed. Taxonomic and phytogeographical details are provided on several species or groups of species from Iberia.  © 2003 The Linnean Society of London, Botanical Journal of the Linnean Society, 2003 , 142 , 395−406.     

CHROMOSOME NUMBERS OF CAMPANULACEAE. III. REVIEW AND INTEGRATION OF DATA FOR SUBFAMILY LOBELIOIDEAE

Chromosome numbers are now known for 153 species in 21 genera of Lobelioideae (Campanulaceae); this represents almost 13% of the species and 70% of the genera in the subfamily. Numbers reported are n = 6, 7, 8, 9, 10, 11, 12, 13, 14, 19, 21, 35, 70. The subfamily as a whole has x = 7; the best documented exception is Downingia and its allies with x = 11. Only four genera show interspecific variation in chromosome number: Downingia (n = 6, 8, 9, 10, 11, 12); Lobelia (n = 6, 7, 9, 12, 13, 14, 19, 21); Pralia (n = 6, 7, 13, 14, 21, 35, 70); and Solenopsis (n = 11, 14). Intraspecific variation occurs in 13 species, with as many as four different cytotypes in one species. The herbaceous members of the subfamily as a group are quite variable, showing the entire range of chromosome numbers, including numerous dysploids, but are predominantly diploid. The woody species, by contrast, are much less variable; nearly all of the species are tetraploid, with only a few diploids and hexaploids and no dysploid numbers known. These data support the hypothesis that woodiness is apomorphic within the subfamily. A general trend of higher chromosome numbers at higher latitudes and higher elevations is evident within the subfamily. The chromosome number of Apetahia raiateensis (n = 14) is reported here for the first time, on the basis of a count made about 30 years ago by Peter Raven.     

A comparative chromosome banding analysis of the Ursidae and their relationship to other carnivores

Trypsin G-banded karyotypes of eight species of Ursidae were prepared from retrovirus-transformed skin fibroblast cultures. The banding patterns of all bears are highly conserved, even though their diploid numbers range from 42 to 72. A comprehensive analysis of the homologous banding patterns within the Ursidae and with a hypothesized ancestral carnivore karyotype permitted the reconstruction of three significant chromosomal reorganization events that occurred during the evolution of the modern ursids. The first was a multichromosomal fissioning away from the biarmed (2n = 44) primitive carnivore karyotype, leading to six species of the Ursinae subfamily (2n = 78). The second was a comprehensive chromosome fusion in the lineage that led to the Ailuropodinae (giant panda) subfamily (2n = 44). The third event was a second, independent, but less extensive, centromeric fusion occurring in the line that led to the Tremarctinae (spectacled bear) subfamily (2n = 52). Ursidae karyotypes are not only highly conserved within the family but also exhibit extensive chromosome banding homology with other carnivore families.     

Cytotaxonomy of the apocynaceae

At present there is karyological information on ca 10% of the species and ca 30% of the genera of the Apocynaceae. Basic numbers of x = 6, 8, 9, 10, 11, 12, 16, 18, 20, 21 and 23 have been assessed. Of these x = 11 is primitive, occurring in ca 60% of the genera. Those of x = 6, 8, 9 and 10 have evolved by reduction, and x = 12 by increase from x = 11. In the subtribe Secondatiinae however, x = 12 is most likely the result of doubling x = 6. The numbers x = 16, 18 and 20 are likewise doubles of x = 8, 9 and 10 respectively. Those of x = 21, 23, and in one case, x = 20 are probably aneuploid products of doubles of x = 11. The two larger subfamilies, Plumerioideae and Apocynoideae have the basic numbers x = 8, 9, 10 and 11 in common and are not separable on the basis of chromosomal evidence. The third small subfamily Cerberoideae is more homogeneous according to basic number, i.e. x = 10 and 20. Most genera are characterized by a constant basic number, but some have two basic numbers; these clearly are cases of infrageneric aneuploidy. Based on records in the literature two closely related generaApocynum andTrachomitum appear to be characterized by a basic number of x = 8 as well as x = 11. This conflicting situation should be clarified by further karyological research. From the level of subtribe onwards some taxa have one basic number, but others are characterized by two or more numbers. The occurrence of similar basic numbers in different phylads of the family is considered to be the result of similar chromosomal evolution mechanisms. Approximately 22% of the investigated species are polyploid. Intrageneric polyploidy occurs with a frequency of about 12.5% and infraspecific polyploidy with less than 4%. The karyotypes observed are symmetrical: the chromosomes within a karyotype are similar in length with primary constrictions usually in a median position. In the Tabernaemontaneae however, it was observed that the karyotypes comprise one pair of distinctly heterobrachial chromosomes in addition to the metacentric ones. This tribe is also characterized by chromosomes which are relatively long. Most genera of the African continent, which are well known regarding their chromosome number, are characterized by x = 11. Exceptions areStrophantus (x = 9) with a mainly tropical African distribution. Two other genera with derived numbers, i.e.Gonioma with x = 10 andPachypodium with x = 9, occur in southern Africa and Madagascar. The genera with a non-African distribution are less known for their chromosome number. However, the available evidence suggests that evolution of derived numbers has occurred more frequently outside Africa than on this continent.     

中国云南果蝇属暗果蝇种组的核型分化

观察了新近发现于我国云南的果蝇属暗果蝇种组(Drosophila obscura species group)种类D．luguensis、D．dianensis和D．limingi的有丝分裂中期核型,并将3个种的核型与各自的近缘种类进行了比较。D．luguensis具2n=12条染色体,包括3对中央着丝粒(V形)染色体、2对近端着丝粒(棒状)染色体以及1对微小(点状)染色体。其中X和Y染色体均为中央着丝粒染色体。D．dianensis和D．limingi具2n=10条染色体,包括1对大的V形常染色体,1对小的V形常染色体,2对J形(亚中着丝粒型)常染色体和1对点状染色体。其中X染色体为J形,Y染色体为短棒状。基于核型比较的结果以及D．sinobscura亚组地理分布的资料,结合种间系统发育关系研究结果,认为D．luguensis可能保留了该亚组祖先种类的核型。D．sinobscum的核型(2n=12：2V,1J,2R,1D)可能由一个pre-“sinobscura-hubeiensis”谱系的一个分支通过臂间倒位演化而来,而D．hubeiensis的核型(2n=10：4V,1D)可能由该谱系的另一分支通过着丝粒融合(2对近端着丝粒常染色体的融合)而形成。推测在D．dianensis和近缘欧洲种D．subsilvestris(2n=12：3V,2R,1D)间、D．limingi和东亚近缘种D．tsukubaensis(2n=12：3V,2R,1D)间的物种分化过程中,可能有相似的染色体变异类型发生。     

Chromosome numbers of Panamanian Lecythidaceae and their use in subfamilial classification

Nine species of Lecythidaceae subfamily Lecythidoideae in four genera whose chromosome numbers were previously unknown, have 17 as their basic chromosome number:Eschweilera pittieri, three other unidentified species ofEschweilera, Grias cauliflora, Gustavia dubia, G. superba, Lecythis minor, andL. tuyrana. All are diploid exceptGustavia superba, which is tetraploid.Couroupita guianensis, which was previously—and probably incorrectly—reported to have a gametic chromosome number of 18, also hasn = 17. The known chromosome numbers support recognizing at least three of Niedenzu’s subfamilies: Planchonioideae withx = 13, Napoleonaeoideae withx = 16, and Lecythidoideae withx = 17. His fourth subfamily, Foetidioideae, with one genus of five species, has not been counted. Cytological data have been and probably will be useful in indicating to what subfamily problematic genera belong and in showing interesting phytogeographic patterns within the family. On the other hand, cytological data provide no recognizable clues relating the Lecythidaceae to other families.     

Cytogenetic studies in Pentatomidae (Heteroptera): A review

The suborder Heteroptera constitutes one of the most important insect groups because most species are plants feeders and cause damage on many plants of economic importance. One of the most important cytogenetic characteristics of Heteroptera is the holokinetic nature of the chromosomes. One particular feature of some species of Pentatomidae is the regular presence of an abnormal meiosis in one testicular lobe (harlequin lobe). From the 28 species cytogenetically analysed from Argentine material, 21 present the diploid number 2 n  = 14, four species present a reduced number (2 n  = 12) and another three species possess an increased diploid number (2 n  = 16); among all these only three present an harlequin lobe. In the present work, a bibliographic review of the chromosome number and sex determining system of 294 species and subspecies belonging to 121 genera within the subfamilies Asopinae, Discocephalinae, Edessinae, Pentatominae, Phyllocephalinae and Podopinae is presented. The male diploid numbers range from six to 27 with a mode in 14 chromosomes; this last diploid number is present in 85% of the species. The sex chromosome determining system is XY/XX except in three species: Macropygium reticulare (Fabricius, 1803), Rhytidolomia senilis (Say, 1832) and Thyanta calceata (Say, 1832) which present derived sex chromosome systems. Furthermore, the cytogenetic relationships with the other families of Pentatomoidea are discussed.     

安徽黄山木本植物区系中一些种的细胞学研究（Ⅰ）

报道了黄山地区１８种木本植物的染色体数,分属于１５个科中的１８个属,其中１４种和２个属为首次报道;同时对Ａｐｈａｎａｎｔｈｅ,Ｆｏｒｔｕｎｅａｒｉａ,Ｌｏｒｏｐｅｔａｌｕｍ,Ｈｏｌｂｏｅｌｌｉａ,Ｐｌａｔｙｃａｒｙａ属的染色体数及其在分类上的意义作了简单讨论。     

Comparative cytogenetics of six Indo‐Pacific moray eels (Anguilliformes: Muraenidae) by chromosomal banding and fluorescence in situ hybridization

A comparative cytogenetic analysis, using both conventional staining techniques and fluorescence in situ hybridization, of six Indo‐Pacific moray eels from three different genera (Gymnothorax fimbriatus, Gymnothorax flavimarginatus, Gymnothorax javanicus, Gymnothorax undulatus, Echidna nebulosa and Gymnomuraena zebra), was carried out to investigate the chromosomal differentiation in the family Muraenidae. Four species displayed a diploid chromosome number 2n = 42, which is common among the Muraenidae. Two other species, G. javanicus and G. flavimarginatus, were characterized by different chromosome numbers (2n = 40 and 2n = 36). For most species, a large amount of constitutive heterochromatin was detected in the chromosomes, with species‐specific C‐banding patterns that enabled pairing of the homologous chromosomes. In all species, the major ribosomal genes were localized in the guanine‐cytosine‐rich region of one chromosome pair, but in different chromosomal locations. The (TTAGGG)_n telomeric sequences were mapped onto chromosomal ends in all muraenid species studied. The comparison of the results derived from this study with those available in the literature confirms a substantial conservation of the diploid chromosome number in the Muraenidae and supports the hypothesis that rearrangements have occurred that have diversified their karyotypes. Furthermore, the finding of two species with different diploid chromosome numbers suggests that additional chromosomal rearrangements, such as Robertsonian fusions, have occurred in the karyotype evolution of the Muraenidae.