Karyological notes on three weevil species from Armenia (Coleoptera, Curculionidae, Cleoninae)

Karyological studies were carried out on three Armenian weevil species from the subfamily Cleoninae. The following chromosome numbers were found in individual species: 2n = 38, n Male = 18 + Xyp in Menecleonus anxius (Gyllenhal, 1824), 2n = 40, n Male = 19 + Xyp in Conorhynchus nigrivittis (Pallas, 1781) and 2n = 44, n Male = 21 + Xyp in Lixus iridis Olivier, 1807. The heterochromosomes of all the examined species form, in the first meiotic metaphase, a typical parachute bivalent.     

Chromosome evolution of the blue sheep/bharal (Pseudois nayaur)

A male dwarf blue sheep was collected 60 km south of Batang east to the Jinsha Jiang river, and a male Subei blue sheep (Greater form) was collected from Gansu, China, representing two geographically separated blue sheep forms. Chromosome preparations were prepared from fibroblast cultures. The dwarf blue sheep has a 2n = 54 and a karyotype with three biarmed formations that resulted from acrocentric chromosome fusions (based on the 2n = 60 Capra autosomal equivalents) 14p/5q, 27p/1q, and 29p/2q from the largest to the smallest biarmed chromosome, respectively. The 14p/5q fusion is metacentric, whereas the 27p/1q and 29p/2q are submetacentric. The Subei blue sheep had a 2n = 56, with only the 27p/1q and 29p/2q biarmed chromosome fusions. The remainder of the chromosomes in both blue sheep are acrocentric; the X is the largest acrocentric chromosome and the Y is a minute biarmed chromosome. Our observation is one evidence showing that chromosome evolution within blue sheep has followed a series of centric fusions resulting in the reduction of chromosome number, which is typical of all extant genera within the tribe Caprini.     

Chromosome numbers and karyotypic evolution of Caraboidea

The chromosome numbers of 136 species of the Spanish caraboid fauna were studied. The most frequent karyotypes are 2n=37 (54 species) and 2n=24 (23 species), and the chromosome number ranges from 2n=21 to 2n=69, of which 2n=69 is the highest diploid number hitherto found among the Coleoptera. It is proposed that 2n=37 is the ancestral karyotype of the division Caraboidea and the suborder Adephaga as opposed to that of the suborder Polyphaga, 2n=20. Karyotypic evolution has led to increases and decreases of this number, both tendencies having taken place in four genera. Species of ten genera show a neo-XY bivalent due to an X-autosome fusion. The thirty-three chromosome numbers of Caraboidea reveal that these Coleoptera have a remarkable karyotypical heterogeneity.     

Chromosome evolution in the genus Mikania (Compositae)

Karyotypic analysis of ten species of the genus Mikania was carried out using Feulgen staining. Species belonging to the following sections were analyzed: Section Thyrsigerae containing M. additicia (2n = 34), M. hemisphaerica, M. lanuginosa, and M. punctata (2n = 36), and Mikania sericea (2n = 42), which adds a new basic chromosome number (x = 21) to the genus and to the tribe Eupatorieae; Section Corymbosae with M. hastato-cordata (2n = 34) and M. involucrata and M. microptera with 2n = 36 chromosomes; Section Spicato-Racemosae with M. sessilifolia, with 2n = 108 chromosomes. One unidentified species with 2n = 34 chromosomes was also analyzed. All the species studied show one large pair of chromosomes with a secondary constriction in the middle region of the long arm. The morphology of this chromosome suggests that it can be considered as a cytological marker for the genus. Because of the distinctive inflorescence types found in the genus Mikania and the high frequency of species with x = 18, a correlation between morphological and chromosomal evolution is discussed. The present study suggests that the basic original chromosome number for the genus is x = 18, from which the others (x = 17, 19, 20, 21) have been derived by aneuploidy to form the observed aneuploid series.     

Identification of mitotic chromosomes of tuberous and non-tuberous solanum species (Solanum tuberosum and Solanum brevidens) by GISH in their interspecific hybrids.

GISH (genomic in situ hybridization) was applied for the analysis of mitotic chromosome constitutions of somatic hybrids and their derivatives between dihaploid clones of cultivated potato (Solanum tuberosum L.) (2n = 2x = 24, AA genome) and the diploid, non-tuberous, wild species Solanum brevidens Phil. (2n = 2x = 24, EE genome). Of the primary somatic hybrids, both tetraploid (2n = 4x) and hexaploid (2n = 6x) plants were found with the genomic constitutions of AAEE and AAEEEE, respectively. Androgenic haploids (somatohaploids) derived from the tetraploid somatic hybrids had the genomic constitutions of AE (2n = 2x = 24) and haploids originating from the hexaploid hybrids were triploid AEE (2n = 3x = 33 and 2n = 3x = 36). As a result of subsequent somatic hybridization from a fusion between dihaploid S. tuberosum (2n = 2x = 24, genome AA) and a triploid somatohaploid (2n = 3x = 33, genome AEE), second-generation somatic hybrids were obtained. These somatic hybrids were pentaploids (2n = 5x, genome AAAEE), but had variable chromosome numbers. GISH analysis revealed that both primary and second-generation somatic hybrids had lost more chromosomes of S. brevidens than of S. tuberosum.     

Chromosome differentiation of spiny rats of the genus Proechimys (Rodentia, Echimyidae)]

Karyological analysis of spiny rats of the genus Proechimys revealed four chromosome forms: 2n = 30; 2n = 29; 2n = 28; 2n = 24. 30-chromosome spiny rats are characterized by unique karyotype constitution. 27-chromosome spiny rats from the territory near Iquitos differ from the same of Pucalpa (Ucayali Department) by Y-chromosome structure and banding of long arms with two pairs of autosomes. 24-chromosome rats from the regions mentioned above do not differ in G-banded chromosomes. Diploid chromosome set equal to 29, has a family originated from the parents which had 2n = 30 and 2n = 28 under the laboratory conditions. The absence of clear morphological differentiation, similarity of constituent parts of the karyotype and hybridization possibility point to relatively recent origination of the chromosome forms under study.     

Chromosome evolution in the genus Ophioglossum L.

Cytological observations on eleven species of Ophioglossum revealed low gametic ( n ) chromosome numbers of 30, 34 and 60 in populations of O.eliminatum , contrasting with an earlier report of n = 90 in the same species. The rest of the species is based on n =120.Cytologically studied species of Ophioglossum exhibit a range of chromosome numbers from n = 30 in O.eliminatum to n =720 in O.reticulatum. The weighted highest common factor (HGF) from all the reported chromosome numbers in twelve species was found to be 30. This number is proposed as the palaeobasic chromosome number for the genuS. Reported chromosome numbers which are not multiples of 30 were subjected to sequential analysis, yielding three distinct ultimate base numbers, 4, 5 and 6, which can produce n = 30 in seven different ways. The neobasic number, n= 120, appears to have arisen through various combinations and permutations of these, theoretically 2401 routes; only a relatively few of these routes exist today, suggesting that extreme selection has been exerted against the majority, and further suggesting that Ophioglossum represents an evolutionary dead end through repeated cycles of polyploidy and is possibly at the verge of extinction. The stoichiometric model of evolution, which derives the various chromosome numbers possessed by the twelve species from the basic and ultimate basic chromosome numbers, is used to explain chromosomal evolution in the genus.     

Chromosomal evolution in the South American Nymphalidae

We give the chromosome numbers of about 80 species or subspecies of Biblidinae as well as of numbers of neotropical Libytheinae (one species), Cyrestinae (4) Apaturinae (7), Nymphalinae (about 40), Limenitidinae (16) and Heliconiinae (11). Libytheana has about n=32, the Biblidinae, Apaturinae and Nymphalinae have in general n=31, the Limenitidinae have n=30, the few Argynnini n=31 and the few species of Acraeni studied have also mostly n=31. The results agree with earlier data from the Afrotropical species of these taxa. We supplement these data with our earlier observations on Heliconiini, Danainae and the Neotropical Satyroid taxa. The lepidopteran modal n=29-31 represents clearly the ancestral condition among the Nymphalidae, from which taxa with various chromosome numbers have differentiated. The overall results show that Neotropical taxa have a tendency to evolve karyotype instability, which is in stark contrast to the otherwise stable chromosome numbers that characterize both Lepidoptera and Trichoptera.     

Cytogenetics studies in Brazilian species of Pseudophyllinae (Orthoptera: Tettigoniidae): 2n(♂)=35 and fn=35 the probable basic and ancestral karyotype of the family Tettigoniidae

The karyotypes of five species of Brazilian Pseudophyllinae belonging to four tribes were here studied. The data available in the literature altogether with those obtained with species in here studied allowed us to infer that 2n(♂)=35 is the highest chromosome number found in the family Tettigoniidae and that it is present in species belonging to Pseudophyllinae, Zaprochilinae and in one species of Tettigoniinae. In spite of that all five species exhibit secondary karyotypes arisen surely by a mechanism of chromosomal rearrangement of centric fusion, tandem fusion and centric inversion types from those with 2n(♂)=35 and FN=35, they share some common traits. The X chromosome is submetacentric (FN=36), heteropicnotic during the first prophase, the largest of the set but its size is rather variable among the species and the sex chromosomal mechanism is of the XO( ♂ ), XX( ♀ ) type. The chromosomal rearrangements involved in the karyotype evolution of the Pseudophyllinae and its relationship with those of the family Tettigoniidae are discussed and we propose that the basic and the ancestral karyotype of the Tettigoniidae is formed by 2n(♂)=35, FN=35 and not by 2n(♂)=31, FN= 31, as usually accepted.     

角蒿属6个种的核形态学研究

对紫葳科角蒿属（Incarvillea)6种植物（其中两头毛Incarvillen arguta包括红花和白花2个类型）进行了核形态学研究,它们的间期核均为简单染色中心型,前期染色体为中国型,体细胞中期染色体数目均为2n=22,核型公式分别为：（1）两头毛（红花类型）Incanillea ar-guta(Red-flower form)2n=22=14m (2SAT) 8sm(lSAT),着丝点端化值（T.C.%)为62.71%,臂指数（N.F.值）为44;（la)两头毛（白花类型I.arguta(White-flower form)2n=22=16sm(lSAT) 6st,T.C.%值为70.62%,N.F值为38;（2）鸡肉参I.mairei 2n=22=6m 8sm(lSAT) 8st,T.C.%值为70.07%,N.F.值为36;（3）红波罗花I.delavayi 2n=22=10m 6sm 6st,T.C.%值为61.33%,N.F.值为38;（4）单叶波罗花I.forrestii2n=22\4m 8sm 10st(lSAT).T.C.%值为73.10%,N.F.值为34;（5）中甸角蒿I.zhongdianensis2n=22=4m 8sm 10st,T.C.%值为72.31%,N.F.值为34;（6）黄波罗花I.lutea2n=22=4m 8sm(2SAT) 10st,T.C.%值为69.47%,N.F.值为34。上述几种植物中,除两头毛（红花类型）的核型不对称性为2A型外,其余几种的核型不对称性都属于3A型,本文观察的6种植物的核形态结构均为首次报道。     

稀莶属三种植物的核形态学研究

研究了稀莶属３种植物的染色体核形态结构,除稀莶的染色体数目曾有报道外,毛梗稀莶、腺梗稀莶还未有报道,３种植物的核型为首次报道。它们的静止核均属于复杂染色中心微粒型,分裂前期染色体均属于渐变型。中期体细胞染色体数目都为２ｎ＝３０,本属的染色体基数为ｘ＝１５,核型分别为：（１）腺梗稀莶２ｎ＝３０＝２９ｍ＋１ｓｍ,属于１Ｂ型;（２）毛梗稀莶２ｎ＝３０＝２８ｍ＋２ｓｍ,属于１Ｂ型;（３）稀莶２ｎ＝３０＝２     

Observations of Chromosomes of Malus Species in China

Somatic chromosome numbers of 37 forms (representing 22 species) of apples in China were counted using wall-degradation and hypotonic method. Among the species investigated 3 categories of chromosome numbers, i.e. 2n=34, 51 and 68 are confirmed. The chromosome numbers of the following species are here first reported: Malus ombrophila 2n= 34, M. prattii 2n=34, M. melliana 2n=34, Zhaojiaohonghua (M. sp.) 2n=34, and M. asiatica var. 2n=68. Polyploids (including infraspecific polyploids) account for 41% of the total number of the species investigated. 51 is a predominant number. It is suggested that ploidy variation is an important pathway in apple evolution in China, and triploid may be considered as a suitable evolution grade. There are rich apple germplasm resources in China. The systematic studies of this genus are obviously essential.     

Karyotypic study of Echinops (Asteraceae) in Fars Province, Iran

A karyotypic study was performed on 19 Echinops species in Fars Province, Iran. The taxa revealed chromosome counts of 2 n = 28, 30, 32 and 34. Somatic chromosome numbers of 18 species are reported for the first time. Using somatic chromosome number as a criterion for section delimitation, the transfer of E. gedrosiacus, E. cyanocephalm and E. sojakii from Sect. Oligolepis to Sect. Ritropsis is suggested. Differences in basic chromosome numbers point towards the possible role played by centric fusion/fission in the karyotypic evolution of the genus. The Karl Pearson coefficient of correlation and principal components analysis indicated the occurrence of structural changes in chromosomes. The species occupied classes 1A, 2A & 2B of Stebbins' karyotype classification, indicating the presence of a primitive symmetrical karyotype in the genus.     

蜘蛛抱蛋属植物的核型不对称性分析

报道了蜘蛛抱蛋属(Aspidistra)两种植物的染色体数目和核型,其中河口蜘蛛抱蛋(A.hekouensi)的染色体数目(2n=38)为首次报道,四川蜘蛛抱蛋(A.sichuanensis)染色体数目也为2n=38,但其核型与以往的报道有差别.使用染色体内不对称系数(A1)和染色体间不对称系数(A2)对该属34种植物核型的不对称性进行了分析,结果表明该属植物的核型似乎并没有向不对称性增强的方向演化.     

Chromosome numbers in some North American species of the genus Cirsium. III. Western United States,Mexico, and Guatemala

New data are presented on chromosome numbers for 36 species, two varieties, and two hybrids ofCirsium (Compositae). These include first reports forC. rhothophilum (2n = 34),C. andrewsii (2n = 32),C. crassicaule (2n = 32),C. quercetorum (2n= 32, 112),C. pascuarense (2n= 32),C. douglasii var.canescens (2n = 30, 34),C. hydrophilum (2n = 32),C. neomexicanum (2n = 30),C. cymosum (2n = 30, 34),C. acantholepis (2n= 34),C. radians (2n = 34), C.grahami (2n = 32),C. nigriceps (2n = 36),C. andersonii (2n= 32, 64),C. anartiolepis (2n = 34), andC. subcoriaceum (2n= 34). The published data on chromosome numbers of Eurasian and AmericanCirsium are summarized. In Eurasia, speciation has taken place primarily at the diploid level but is occasionally reinforced by polyploidy. The ancestral base number of 17 has been preserved in almost all species, and there is little evidence that reduction in chromosome number has played a significant role in speciation. In America speciation has proceeded exclusively at the diploid level, but the ancestral genome of 17 chromosomes has been retained in only about half of the species examined. In the remaining species, restructuring of the genome has occurred resulting in a reduction in number from 17 to 9 in extreme cases. Polyploidy, when seen, is of no significance. It is suggested that all species with greatly reduced numbers may represent products of a single reduction series.     

High allozyme variation in populations of three spiny rat species from Upper Amazonia: association with ecology and evolution]

The allozyme variation in three spiny rat species of the genus Proechimys from Upper Amazonia was studied in relation to their ecology and evolution. The ecological environmental factors and biotopic distribution of species were analyzed. The unusually high allozyme variation was found in P. simonsi and P. sp. (2n = 34) inhabiting native forest biotopes. A relatively low allozyme variation in P. brevicauda was assumed to be associated with eurybiotic properties and the ability of this species to adapt to anthropogenic biotopes. Data on chromosome homeology and reconstruction of chromosome rearrangements in six spiny rat species were correlated with allozyme variation. The results suggested that chromosome rearrangements played the major role in evolution of the spiny rat species, and that the reorganization of the P. brevicauda genome was not random. P. simonsi and P. sp. (2n = 34), which live in native forest biotopes and carry an excessive genomik "informational load", were assumed to be highly susceptible to any novel external factors. These species are potentially able to produce new chromosome forms and are most significantly affected by deforestation.     

Chromosome counts in some Chinese ferns

The spore mother cells of six species of Chinese homosporous ferns have been examined, among them the chromosome numbers of five species, Adiantum capillus-junonis Rupr. (n= 30), Ctenitis rhodolepis (Clarke) Ching (n = 41), Cyclogramma flexilis (Christ) Tagawa (n = 68), Leptogramma scallani (Christ) Ching (n = 36) and Vandenboschia auriculata (B1.) Copel. (n=36), from Emei Shan (Omei) Sichuan province are recorded for the first time. The chromosome number n=68 from the species Cyclogramma flexilis suggests that the base number for this genus is 34. Another species, Athyrium brevifrons Nakai from Wuling Shah Beijing (Peking) has a gameticchromosome number n=40, as already reported by K. Mitui and H. Hirabayashi.     

Karyotype differentiation in Chromaphyosemion killifishes (Cyprinodontiformes, Nothobranchiidae). III: extensive karyotypic variability associated with low mitochondrial haplotype differentiation in C. bivittatum

We investigated chromosomal evolution in the African killifish species Chromaphyosemion bivittatum using a combination of cytogenetic and phylogenetic methods. Specimens from five populations were examined by conventional Giemsa staining as well as sequential chromosome banding with 4',6-diamidino-2-phenylindole (DAPI), chromomycin A(3) (CMA(3)), AgNO(3)-staining and C-banding. The cytogenetic analysis revealed variability in 2n ranging from 2n = 29 to 2n = 36 and in NF ranging from NF = 38 to NF = 44. Two populations showed an extensive chromosomal polymorphism (2n = 29-34, NF = 44 and 2n = 32-34, NF = 38-42, respectively). Karyotypic variability within and among populations was mainly due to Robertsonian translocations and heterochromatin additions, and chromosome banding patterns suggested that both types of chromosomal rearrangements were related to the presence of AT-rich heterochromatin. A phylogenetic analysis of the partial mitochondrial (mt) cytochrome b gene, using specimens from eleven populations, revealed a low degree of haplotype differentiation, which suggested a relatively recent divergence of the populations examined. This finding conformed to the low degree of morphological differentiation observed among C. bivittatum populations and might indicate fast chromosomal evolution. The high karyotypic variability may be caused by an elevated chromosomal mutation rate as well as certain aspects of the mating system and population dynamics of C. bivittatum facilitating the fixation of new chromosomal variants.     

Chromosome evolution involving Robertsonian rearrangements in Xyrichthys fish (Labridae, Perciformes)

Three Xyrichthys fish (Labridae, Perciformes), X. pavo, X. dea, and X. twistii, were cytogenetically studied. X. pavo and X. dea had 2n = 44 chromosomes, which were all acrocentric. X. twistii had 2n = 22 chromosomes consisting of eighteen meta- and submetacentric and four acrocentric chromosomes. The cellular DNA contents of X. pavo and X. twistii measured using flow cytometry were nearly equal. These results suggest that the karyotype of X. twistii evolved by decreasing the number of chromosomes by fusion events, probably Robertsonian fusion. Cytogenetic relationships among the three species were surmized on the basis of features on the karyotypes and the NOR locations. A large gap in the chromosome number between 2n = 44 and 2n = 22 is an interesting feature related to the process of chromosome evolution.     

四十五种叶蝉的染色体研究（同翅目：叶蝉总科）

研究观察了45种中国雄性叶蝉的减数分裂,其中44种的核型为首次报道,染色体数目变化在2n=12～26之间,性别决定均为XO型。从叶蝉总科的组型图来看,该科染色体数目变化在2n=8～28之间,峰值为2n=18(16+XO),另外几种类型2n=16,20,22也有较高的出现频率。科内染色体数目的进化不具有明显的方向性,2n=22(20+XO)是该科的原始核型,易位导致的不均等互换可能是染色体数目进化的主要机制。从精子发生来看叶蝉总科与角蝉总科的关系较为密切,两者的共同特点是：①精母细胞体积较大,显著不同于沫蝉和蝉科;②减数分裂行为及精子变态过程相似;③染色体数目较少,染色体体积较大;④减数分裂前期具有典型的花束期,没有弥散期,因而不同于蜡蝉。但是由于叶蝉总科的染色体变异范围明显大于角蝉总科,而角蝉总科的核型相对较为保守,从核型上来说角蝉总科是比叶蝉总科较为原始的类群。