Small stonefly predators affect microbenthic and meiobenthic communities in stream leaf packs

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Retrotransposon Mys was active during evolution of the Peromyscus leucopus-maniculatus complex

Mys is a retrovirus-like transposable element found throughout the genus Peromyscus. Several mys subfamilies identified on the basis of restriction site variation occur in more than one species. The distribution of these subfamilies is consistent with the accepted species phylogeny, suggesting that mys was present in the ancestor of Peromyscus and has been active through much of the evolution of this genus. Quantitative Southern blot analysis was used to examine the variability of subfamilies in P. leucopus and maniculatus. We found that subfamilies with phylogenetically narrow distributions were more variable in copy number both within and between species than subfamilies with a broader distribution. Taken together, our data suggest that mys has undergone multiple rounds of transposition since the peromyscine radiation, and that five subfamilies have been amplified during the evolution of the leucopus-maniculatus species complex. Correspondence to: H.A. Wichman     

Evolution of the active sequences of the HpaI short interspersed elements

Ninety-nine members of the salmonid HpaI and AvaIII families of short interspersed repetitive elements (SINEs) were aligned and a general consensus sequence was deduced. The presence of 26 correlated changes in nucleotides (diagnostic nucleotides) from those in the consensus sequence allowed us to divide the members of the HpaI family into 12 subfamilies and those of the AvaIII family into two subfamilies. On the basis of the average sequence divergences and the phylogenetic distributions of the subfamilies, the relative antiquity of the subfamilies and the process of sequential changes in the respective source sequences were inferred. Despite the higher mutation rates of CG dinucleotides in individual dispersed members, no hypermutability of CG positions was observed in changes in the source sequences. This result suggests that sequences of SINEs located in a nonmethylated or hypomethylated genomic region could have been selected as source sequences for retroposition and/or that some CG sites are the parts of recognition sequences of retropositional machineries. Correspondence to: N. Okada     

Morphological phylogeny of the variable fly family Stratiomyidae (Insecta,Diptera)

Brammer, C. A. & von Dohlen, C. D. (2010). Morphological phylogeny of the variable fly family Stratiomyidae (Insecta, Diptera). —Zoologica Scripta, 39, 363–377. Stratiomyidae is a dipteran family distributed worldwide and containing 2800 species classified into 12 subfamilies. Previous phylogenetic work on the Stratiomyidae consisted of a 20‐character morphological analysis of the subfamilies [ World Catalog of the Stratiomyidae (Insect: Diptera). Leiden: Backhuys Publishers, 2001 ], and a molecular study using 69 taxa and two gene regions [ Molecular Phylogenetics and Evolution, 43, 2007, 660 ]. In this study, we present an expanded morphological cladistic analysis using 92 characters and 80 taxa, representing 36 of 39 described genera and all 12 Stratiomyidae subfamilies, as well as Xylomyidae and Pantophthalmidae outgroups. Data are analysed under maximum parsimony with all characters unordered and weighted equally; nodal support is assessed with the bootstrap and Bremer index. The strict consensus of all shortest trees is well resolved, and many of the deeper nodes are supported, although the root is ambiguous. Antissinae, Stratiomyinae, Sarginae and the diverse Clitellariinae are not monophyletic. Clitellariinae are positioned across several lineages, with most species grouped into a single, unsupported clade. Many of the well‐supported relationships are consistent with several aspects of the previous studies. The position of Exodontha remains elusive. Character support for subfamilies and other major clades is discussed.     

Phylogenetic relationships of subfamilies and circumscription of tribes in the family Hesperiidae (Lepidoptera: Hesperioidea)

A comprehensive tribal‐level classification for the world’s subfamilies of Hesperiidae, the skipper butterflies, is proposed for the first time. Phylogenetic relationships between tribes and subfamilies are inferred using DNA sequence data from three gene regions (cytochrome oxidase subunit I‐subunit II, elongation factor‐1α and wingless). Monophyly of the family is strongly supported, as are some of the traditionally recognized subfamilies, with the following relationships: (Coeliadinae + (“Pyrginae” + (Heteropterinae + (Trapezitinae + Hesperiinae)))). The subfamily Pyrginae of contemporary authors was recovered as a paraphyletic grade of taxa. The formerly recognized subfamily Pyrrhopyginae, although monophyletic, is downgraded to a tribe of the “Pyrginae”. The former subfamily Megathyminae is an infra‐tribal group of the Hesperiinae. The Australian endemic Euschemon rafflesia is a hesperiid, possibly related to “Pyrginae” (Eudamini). Most of the traditionally recognized groups and subgroups of genera currently employed to partition the subfamilies of the Hesperiidae are not monophyletic. We recognize eight pyrgine and six hesperiine tribes, including the new tribe Moncini. © The Willi Hennig Society 2008.     

Ovarian structure and oogenesis of the oviparous goodeids Crenichthys baileyi (Gilbert, 1893) and Empetrichthys latos Miller, 1948 (teleostei,Cyprinodontiformes)

The cyprinodontiform family Goodeidae comprises two biogeographically disjunct subfamilies: the viviparous Goodeinae endemic to the Mexican Plateau, and the oviparous Empetrichthyinae, known only from relict taxa in Nevada and California. Ovarian characteristics of two oviparous species of goodeid, Crenichthys baileyi and Empetrichthys latos, studied using museum collections, are compared with those of viviparous species of goodeids. Both subfamilies have a single, cystovarian ovary. The ovary in the viviparous Goodeinae has an internal septum that divides the ovarian lumen into two compartments, and it may possess oogonia. There is no ovarian septum in the oviparous C. baileyi and E. latos. Oogenesis is similar in both subfamilies with regard to the proliferation of oogonia, initiation of meiosis, primary growth and development of an oocyte during secondary growth in which fluid yolk progressively fuses into a single globule. Notably, eggs of C. baileyi and E. latos are approximately double the size of those of the viviparous Goodeinae in which embryos develop inside the ovarian lumen and are nourished, in part, by nutrients transferred from the maternal tissues, a mode of embryo development called matrotrophy. Egg envelopes of the two subfamilies differ in that those of C. baileyi and E. latos have a relatively thick zona pellucida, attachment fibrils or filaments that develop between the follicle cells during oogenesis, and a micropyle observed only in E. latos. In contrast, viviparous goodeid eggs have a relatively thin zona pellucida, but lack adhesive fibrils, and a micropyle was not observed. These reproductive characters are compared with those of species of the eastern North American Fundulus, a representative oviparous cyprinodontiform. One newlyrecognized shared, derived character, a single, median ovoid ovary with no obvious external evidence of fusion, supports monophyly of the Goodeidae. Differences among the goodeid subfamilies and Fundulus are interpreted relative to the oviparous versus viviparous modes of reproduction. J. Morphol., 2012. © 2011 Wiley Periodicals, Inc.     

Molecular phylogeny of Pamphagidae (Acridoidea,Orthoptera) from China based on mitochondrial cytochrome oxidase II sequences

Abstract Phylogenetic relationships of Pamphagidae were examined using cytochrome oxidase subunit II (COII) mtDNA sequences (684 bp). Twenty‐seven species of Acridoidea from 20 genera were sequenced to obtain mtDNA data, along with four species from the GenBank nucleotide database. The purpose of this study was analyzing the phylogenetic relationships among subfamilies within Pamphagidae and interpreting the phylogenetic position of this family within the Acridoidea superfamily. Phylogenetic trees were reconstructed using neighbor‐joining (NJ), maximum parsimony (MP) and Bayesian inference (BI) methods. The 684 bp analyzed fragment included 126 parsimony informative sites. Sequences diverged 1.0%–11.1% between genera within subfamilies, and 8.8%–12.3% between subfamilies. Amino acid sequence diverged 0–6.1% between genera within subfamilies, and 0.4%–7.5% between subfamilies. Our phylogenetic trees revealed the monophyly of Pamphagidae and three distinct major groups within this family. Moreover, several well supported and stable clades were found in Pamphagidae. The global clustering results were similar to that obtained through classical morphological classification: Prionotropisinae, Thrinchinae and Pamphaginae were monophyletic groups. However, the current genus Filchnerella (Prionotropisinae) was not a monophyletic group and the genus Asiotmethis (Prionotropisinae) was a sister group of the genus Thrinchus (Thrinchinae). Further molecular and morphological studies are required to clarify the phylogenetic relationships of the genera Filchnerella and Asiotmethis.     

Characterization of four mitochondrial genomes of Crambidae (Lepidoptera,Pyraloidea) and phylogenetic implications

Loxostege turbidalis, Loxostege aeruginalis, Pyrausta despicata, and Crambus perlellus belong to Crambidae, Pyraloidea. Their mitochondrial genomes (mitogenomes) were successfully sequenced. The mitogenomes of L. turbidalis, L. aeruginalis, P. despicata, and C. perlellus are 15 240 bp, 15 339 bp, 15 389 bp, and 15 440 bp. The four mitogenomes all have a typical insect mitochondrial gene order, including 13 protein-coding genes (PCGs), 22 transfer RNA (tRNA) genes, two ribosomal RNA (rRNA) genes, and one A + T rich region (control region). The PCGs are initiated by the typical ATN codons, except CGA for the cox1 gene. Most PCGs terminate with common codon TAA or TAG, the incomplete codon T is found as the stop codon for cox2, nad4, and nad5. Most tRNA genes exhibit typical cloverleaf structure, except trnS1 (AGN) lacking the dihydrouridine (DHU) arm. The secondary structure of rRNA of four mitogenomes were predicted. Poly-T structure and micro-satellite regions are conserved in control regions. The phylogenetic analyses based on 13 PCGs showed the relationships of subfamilies in Pyraloidea. Pyralidae, and Crambidae are monophyletic, respectively. Pyralidae comprises four subfamilies, which form the following topology with high support values: (Galleriinae + ((Pyralinae + Epipaschiinae)+ Phycitinae)). Crambidae includes seven subfamilies and is divided into two lineages. Pyraustinae and Spilomelinae are sister groups of each other, and form the “PS clade.” Other five subfamilies (Crambinae, Acentropinae, Scopariinae, Schoenobiinae, and Glaphyriinae) form the “non-PS clade” in the Bayesian inference tree. However, Schoenobiinae is not grouped with the other four subfamilies and located at the base of Crambidae in two maximum likelihood trees.     

Amplification and Phylogenetic Relationships of a Subfamily of blood, a Retrotransposable Element of Drosophila

To get a better understanding of the effect of interelement selection on the variation of long terminal repeat retrotransposon families, we have investigated the evolutionary history of blood in the Drosophila melanogaster species complex. We carried out a PCR approach to amplify the 5′ untranslated region from blood in the four species of the complex. This procedure revealed two main classes of size variants. Phylogenetic analyses of nucleotide sequences from these variants and blood elements from the Drosophila Genome Projects database show that elements are grouped according to their size, so that they probably correspond to two subfamilies. These two subfamilies arose prior to the split of the complex, and several facts indicate that the expansion of one of them is leading to the competitive exclusion of the other, at least from the euchromatic regions of the genome. Received: 17 August 2000 / Accepted: 20 November 2000     

Multiple subfamilies of mariner transposable elements are present in stalk-eyed flies (Diptera: Diopsidae)

The Diopsid stalk-eyed flies are an increasingly well-studied group. Presented here is evidence of the first known transposable elements discovered in these flies. The vertumnana mariner subfamily was identified in the Diopsini tribe, but could not be amplified in species of the Sphyracephalini tribe. PCR screening with degenerate primers revealed that multiple mariner subfamilies are present within the Diopsidae. Most of the sequenced elements appear to be pseudogenes; however two subfamilies are shown to be evolving under purifying selection, raising the possibility that mariner is active in some Diopsid species. Evidence is presented of a possible horizontal transfer event involving an unknown Teleopsis species and the Tephritid fly Bactrocera neohumeralis. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

A new model estimating stonefly species production in the West Carpathian torrents

Samples of stoneflies were collected from 15 streams of Slovakia during 1976–2000. The model of growth rate is based on 219 data of 50 stonefly species. The non-linear relationship among growth rate (G) of stoneflies and monthly mean water temperature (T) and body mass (W) is described by equation: G = 0.014W ^−0.19 T ^0.25. The model estimates the species production of the families Taeniopterygidae, Nemouridae, Capniidae, Leuctridae and Perlodidae. This model is combined with Morin’s & Dumont’s (1994) model for Perlidae and Chloroperlidae. There is positive evidence that the total stonefly production of mountain and submountain streams increases with discharge. On the other hand, increasing altitude has a negative influence on production.     

Sequence homogenization and chromosomal localization of VicTR-B satellites differ between closely related Vicia species

Satellite sequences of the VicTR-B family are specific for the genus Vicia (Leguminosae), but their abundance varies among the species, being the highest in Vicia sativa and Vicia grandiflora. In this study, we have sequenced multiple randomly cloned VicTR-B fragments from these two species and analyzed their sequence variability, periodicity, and chromosomal localization. We have found that V. sativa VicTR-B sequences are homogeneous with respect to their nucleotide sequences and periodicity (monomers of 38 bp), whereas V. grandiflora repeats are considerably more variable, occurring in at least four distinct sequence subfamilies. Although the periodicity of 38 bp was conserved in most of the V. grandiflora sequences, one of the subfamilies was composed of higher-order repeats of 186 bp, which originated from a pentamer of the basic repeated unit. Individual VicTR-B subfamilies were preferentially located in either intercalary or subtelomeric regions of chromosomes. Interestingly, two V. grandiflora subfamilies with the highest similarity to V. sativa VicTR-B sequences were located in intercalary heterochromatic bands, showing similar chromosomal distribution as the majority of VicTR-B repeats in V. sativa. The other two V. grandiflora subfamilies showing a considerable divergence from V. sativa sequences were found to be accumulated at subtelomeric regions of V. grandiflora chromosomes.Electronic Supplementary Material Supplementary material is available for this article at and is accessible for authorized users.Communicated by I. Schubert     

Phylogeny of thrips (Insecta: Thysanoptera) based on five molecular loci

The order Thysanoptera (Paraneoptera), commonly known as thrips, displays a wide range of behaviours, and includes several pest species. The classification and suggested relationships among these insects remain morphologically based, and have never been evaluated formally with a comprehensive molecular phylogenetic analysis. We tested the monophyly of the suborders, included families and the recognized subfamilies, and investigated their relationships. Phylogenies were reconstructed based upon 5299 bp from five genetic loci: 18S ribosomal DNA, 28S ribosomal DNA, Histone 3, Tubulin‐alpha I and cytochrome oxidase c subunit I. Ninety‐nine thrips species from seven of the nine families, all six subfamilies and 70 genera were sequenced. Maximum parsimony, maximum likelihood and Bayesian analyses all strongly support a monophyletic Tubulifera and Terebrantia. The families Phlaeothripidae, Aeolothripidae, Melanthripidae and Thripidae are recovered as monophyletic. The relationship of Aeolothripidae and Merothripidae to the rest of Terebrantia is equivocal. Molecular data support previous suggestions that Aeolothripidae or Merothripidae could be a sister to the rest of Terebrantia. Four of the six subfamilies are recovered as monophyletic. The two largest subfamilies, Phlaeothripinae and Thripinae, are paraphyletic and require further study to understand their internal relationships.     

Molecular phylogenetics of Erebidae (Lepidoptera,Noctuoidea)

As a step towards understanding the higher‐level phylogeny and evolutionary affinities of quadrifid noctuoid moths, we have undertaken the first large‐scale molecular phylogenetic analysis of the moth family Erebidae, including almost all subfamilies, as well as most tribes and subtribes. DNA sequence data for one mitochondrial gene (COI) and seven nuclear genes (EF‐1α, wingless, RpS5, IDH, MDH, GAPDH and CAD) were analysed for a total of 237 taxa, principally type genera of higher taxa. Data matrices (6407 bp in total) were analysed by parsimony with equal weighting and model‐based evolutionary methods (maximum likelihood), which revealed a well‐resolved skeleton phylogenetic hypothesis with 18 major lineages, which we treat here as subfamilies of Erebidae. We thus present a new phylogeny for Erebidae consisting of 18 moderate to strongly supported subfamilies: Scoliopteryginae, Rivulinae, Anobinae, Hypeninae, Lymantriinae, Pangraptinae, Herminiinae, Aganainae, Arctiinae, Calpinae, Hypocalinae, Eulepidotinae, Toxocampinae, Tinoliinae, Scolecocampinae, Hypenodinae, Boletobiinae and Erebinae. Where possible, each monophyletic lineage is diagnosed by autapomorphic morphological character states, and within each subfamily, monophyletic tribes and subtribes can be circumscribed, most of which can also be diagnosed by morphological apomorphies. All additional taxa sampled fell within one of the four previously recognized quadrifid families (mostly into Erebidae), which are now found to include two unusual monobasic taxa from New Guinea: Cocytiinae (now in Erebidae: Erebinae) and Eucocytiinae (now in Noctuidae: Pantheinae).     

Molecular phylogeny of the family Coccidae (Hemiptera,Coccomorpha), with a discussion of their waxy ovisacs

Coccidae is one of the major families of scale insects, with many species considered to be serious agricultural or horticultural pests. However, the phylogenetic relationships among coccid subfamilies, tribes and genera are poorly understood because existing hypotheses are based on morphological characters and cladistic analyses. Here, we present the first molecular phylogeny of the family Coccidae based on DNA fragments of a mitochondrial gene (COI), nuclear ribosomal RNA genes (18S and 28S), and elongation factor-1α (EF-1α). We found that some genera (Coccus Linnaeus and Pulvinaria Targioni Tozzetti), tribes (Coccini, Paralecaniini, Pulvinariini and Saissetiini) and subfamilies (Coccinae and Filippiinae) within the family are nonmonophyletic. Formation of a waxy ovisac and the distribution and structures of ventral tubular ducts have been used to define the tribe Pulvinariini morphologically; however, these were found to be homoplastic traits based on ancestral state reconstruction. Accordingly, we propose a new classification of certain groups as follows: (i) the Paralecaniini is raised to subfamily rank, Paralecaniinae stat.n. , except that Neosaissetia Tao, Wong & Chang is retained as a member of Coccinae; (ii) Megapulvinaria Yang and Pulvinarisca Borchsenius are transferred from Coccinae to Pulvinariscinae stat.n. ; and (iii) Metaceronema Takahashi is transferred from Filippiinae to Pulvinariscinae stat.n. We provide amended diagnoses for the newly proposed subfamilies.     

A revised subfamily classification of Tenebrionidae (Coleoptera)

Existing classifications of Tenebrionidae are reviewed briefly. The inclusion of the families Alleculidae, Lagriidae, and Nilionidae in Tenebrionidae is confirmed. The splitting off from this complex of a family, Tentyriidae, by Doyen is discussed and rejected. Various taxa which had been included in Tenebrionidae are excluded, amongst which Syrphetodes, Brouniphylax, Exohadrus, Arthopus, Cotulades, Docalis, and Latometus (=Elascus) have not previously been formally excluded. A new family, Archeocrypticidae, is established and defined briefly for Archeocrypticus, Sivacrypticus, and Enneboeus.

Data from matrices based on adult and larval characters comparing Tenebrionidae with most other families of Tenebrionoidea (=Heteromera) are presented for derived characters in common, and for overall similarity. The families most closely related to Tenebrionidae according to these data are Zopheridae, Chalcodryidae, Merycidae, Archeocrypticidae, Synchroidae, Colydiidae, and Monommatidae; none is very close to Tenebrionidae, which has had a long independent history.

Characters of the subfamilies recognised are tabulated, and interpreted in a phylo‐genetic dendrogram. Phylogeny is discussed in relation to adaptive changes in the biology of the various subfamilies, which are Zolodininae new subfamily, Pimeliinae new sense (including Tentyriinae), Toxicinae new sense, Phrenapatinae new sense (including Archeoglenini new tribe), Diaperinae new sense, Gnathidiinae, Tenebrioninae new sense, Alleculinae, Nilioninae, Lagriinae new sense, Cossyphinae, and Cossyphodinae new status.

Biology, economic importance, copulation, orientation of the aedeagus, and distribution are discussed briefly.

Definitions of the family and subfamilies and a key to subfamilies are given, and keys to tribes are included for the smaller subfamilies. The previously unknown larvae of the genera Zolodinus, Menimus, Archeoglenes, Lepispilus, and Nyctoporis are described in detail. Pupae of Zolodinus and Nyctoporis are described. Keys to larvae include many other genera which were hitherto unknown or poorly known.     

Centromeric retrotransposon lineages predate the maize/rice divergence and differ in abundance and activity

Centromeric retrotransposons (CR) are located almost exclusively at the centromeres of plant chromosomes. Analysis of the emerging Zea mays inbred B73 genome sequence revealed two novel subfamilies of CR elements of maize (CRM), bringing the total number of known CRM subfamilies to four. Orthologous subfamilies of each of these CRM subfamilies were discovered in the rice lineage, and the orthologous relationships were demonstrated with extensive phylogenetic analyses. The much higher number of CRs in maize versus Oryza sativa is due primarily to the recent expansion of the CRM1 subfamily in maize. At least one incomplete copy of a CRM1 homolog was found in O. sativa ssp. indica and O. officinalis, but no member of this subfamily could be detected in the finished O. sativa ssp. japonica genome, implying loss of this prolific subfamily in that subspecies. CRM2 and CRM3, as well as the corresponding rice subfamilies, have been recently active but are present in low numbers. CRM3 is a full-length element related to the non-autonomous CentA, which is the first described CRM. The oldest subfamily (CRM4), as well as its rice counterpart, appears to contain only inactive members that are not located in currently active centromeres. The abundance of active CR elements is correlated with chromosome size in the three plant genomes for which high quality genomic sequence is available, and the emerging picture of CR elements is one in which different subfamilies are active at different evolutionary times. We propose a model by which CR elements might influence chromosome and genome size. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Phylogenetic classification of the family Heteroderidae (Nematoda: Tylenchida)

Summary The family Heteroderidae is revised. On the basis of shared, derived characters sister groups are established and arranged in a phylogenetic tree. A hypothetical, primitive ancestor for the family is defined. The genus Verutus has a large equatorial vulval slit and is considered to be the most primitive form. The genus Meloidodera developed by a reduction in vulval size. Genera which developed later exhibit a subterminally located vulval slit and progressively lost the annulation of the female cuticle. In this process four evolutionary lines emerge: (i) a posterior shift of the vulva and the formation of more or less distinct vulval lips gave rise to the genera Zelandodera and Cryphodera; (ii) changes in the lip configuration of the second-stage juvenile gave rise to the genera Hylonema, Afrodera n.g., Heterodera and Bidera; (iii) changes in the composition of the female cuticle resulted in the genera Thecavermiculatus, Atalodera, Sherodera, Sarisodera and Bellodera n.g. and; (iv) a reduction in vulval slit size led to the development of the genera Dolichodera, Globodera, Cactodera and Punctodera. The genera Ephippiodera and Rhizonema are synonymized with Bidera and Sarisodera respectively. Verutus and Meloidodera are recognized as subfamilies Verutinae and Meloidoderinae and the genera in the four evolutionary lines are recognized as subfamilies Cryphoderinae, Heteroderinae, Ataloderinae and Punctoderinae respectively.Two new genera, Afrodera and Bellodera, are erected for species originally described in Sarisodera and Cryphodera. Both new genera are characterized by a depressed vulval slit and the anus located on the dorsal side of the vulval cone. Differences in lip configuration of the infective juvenile and a postulated difference in female cuticle justifies their placement in different subfamilies. The lip configuration of the infective juveniles in the subfamilies Verutinae, Meloidoderinae, Cryphoderinae, Ataloderinae and Punctoderinae remains basically unchanged. The possible development of this character in the subfamily Heteroderinae is discussed and illustrated. The family Heteroderidae, its six subfamilies and 17 genera are defined or redefined, and for each of the genera the nominal species and their synonyms are listed. New synonyms introduced are: Heterodera rumicis and H. scleranthi of H. trifolii, H. ustinova of Bidera avenae and H. mali of Globodera chaubattia. Cactodera acnidae (Schuster & Brezina, 1979) n. comb. and Dolichodera andinus (Golden, Franco, Jatala & Astogaza, 1983) n. comb. are transferred from Heterodera and Thecavermiculatus respectively. Keys are provided for all taxa for which no suitable keys are available in the literature. Species inquirendae are listed. ac]19840606     

Evolution of karyotypes in snakes

Karyotype analysis and morphometric measurement of the chromosomes of 17 species of snakes have been done. Chromosomes of different species so far worked out in each family have been compared using quantitative methods to derive chromosomal affinities between species of different taxonomic categories. The following conclusions have been drawn: (i) It is suggested that the retention of Xenopeltidae as a separate family is unnecessary and the only species Xenopeltis unicolor referred to in that group should be included in the family Boidae. (ii) The subfamilies, Boinae and Pythoninae cannot be distinguished chromosomally. (iii) On the basis of chromosomal similarities, the cytologically known species of Colubridae. have been put into 13 different groupings which do not always correspond to the views of the present day colubrid taxonomists. (iv) In Hydrophiidae, speciation seems to have occurred through changes in the 4th pair of autosomes and sex chromosomes in general and the W chromosome in particular. Evidences are presented to show that fission and inversion have played an important role in bringing about the structural rearrangements in this group. (v) Family Viperidae according to taxonomists is divided into two subfamilies. Both the subfamilies are chromosomally very similar.