The Systematic and Ecological Significance of Anatomical Characters of Leaves in the Tribe Thermopsideae (Fabaceae)

Anatomical characters of leaves of Chinese species of the tribe Thermopsideae, including 3 genera and 13 species, were compared. The results show that the differentiation of mesophyll cells, stomatal types, stomatal distribution and density, shape of epidermal cell, trichome shape and density, cuticular membrane and waxy ornamentation have important systematic and ecological significance among the genera of the tribe. With regard to leaf architecture, pollen morphology and external morphology studies, we suggest that Ammopiptanthus represents an isolated and primitive genus in the tribe and Piptanthus is closely related to Thermopsis. Although different vein-endings, stomatal types and trichomes indicate systematic differences, other characters, such as mesophyll type, stomatal distribution, trichome density etc. are the result of ecological adaptation among the genera. Results of the present study confirm our previous conclusion that two evolutionary trends exist in the tribe, the first towards xerophilization and the second towards cold-adaptation They are caused by the desertification of the central Asian area and the heave of intermountainous plateau. Ecological isolation may be a main evolutary motivation among the taxa in the tribe. We have obs'erved that stomatal density and size in the xeromorphic genus, Ammopipianthus, are not simply a result of the general trend in xerophytes to have high stomatal density correlating with the relatively small size. On the contrary, stomata in this genus are larger than those in the mesophytic genus, Piptanthus, and the density on the lower surface is much less than in the latter. However, stomatal density on the upper surface follows the trend in concordance with increasing aridity and altitute.     

Phylogenetic relationships in Peniocereus (Cactaceae) inferred from plastid DNA sequence data

The phylogenetic relationships of Peniocereus (Cactaceae) species were studied using parsimony analyses of DNA sequence data. The plastid rpl16 and trnL-F regions were sequenced for 98 taxa including 17 species of Peniocereus, representatives from all genera of tribe Pachycereeae, four genera of tribe Hylocereeae, as well as from three additional outgroup genera of tribes Calymmantheae, Notocacteae, and Trichocereeae. Phylogenetic analyses support neither the monophyly of Peniocereus as currently circumscribed, nor the monophyly of tribe Pachycereeae since species of Peniocereus subgenus Pseudoacanthocereus are embedded within tribe Hylocereeae. Furthermore, these results show that the eight species of Peniocereus subgenus Peniocereus (Peniocereus sensu stricto) form a well-supported clade within subtribe Pachycereinae; P. serpentinus is also a member of this subtribe, but is sister to Bergerocactus. Moreover, Nyctocereus should be resurrected as a monotypic genus. Species of Peniocereus subgenus Pseudoacanthocereus are positioned among species of Acanthocereus within tribe Hylocereeae, indicating that they may be better classified within that genus. A number of morphological and anatomical characters, especially related to the presence or absence of dimorphic branches, are discussed to support these relationships.     

Molecular phylogeny of the fungus gnat tribe Exechiini (Mycetophilidae, Diptera)

The phylogenetic relationships within the fungus gnat tribe Exechiini have been left unattended for many years. Recent studies have not shed much light on the intergeneric relationship within the tribe. Here the first attempt to resolve the phylogeny of the tribe Exechiini using molecular markers is presented. The nuclear 18S and the mitochondrial 16S, and cytochrome oxidase subunit I (COI) genes were successfully sequenced for 20 species representing 15 Exechiini genera and five outgroup genera. Bayesian, maximum parsimony and maximum likelihood analyses revealed basically congruent tree topologies and the monophyly of Exechiini, including the genus Cordyla , is confirmed. The molecular data corroborate previous morphological studies in several aspects. Cordyla is found in a basal clade together with Brachypeza , Pseudorymosia and Stigmatomeria . The splitting of the genera Allodiopsis s.l. and Brevicornu s.l. as well as the sistergroup relationship of Exechia and Exechiopsis is also supported. The limited phylogenetic information provided by morphological characters is mirrored in the limited resolution of the molecular markers used in this study. Short internal and long-terminal branches obtained may indicate a rapid radiation of the Exechiini genera during a short evolutionary period.     

The diversification of South American murid rodents: evidence from mitochondrial DNA sequence data for the akodontine tribe

Phylogenetic relationships based on 801 base pairs (bp) of the mitochondrial cytochrome b gene are examined for eight genera and 28 species of the akodontine tribe of South American murid rodents. The akodontine tribe comprises some 35% of the total diversity of the subfamily Sigmodontinae, but the current taxonomy at virtually all levels is uncertain because of inadequate generic diagnoses and assessments of variation and trends in traditional morphological characters. Monophyly of the tribe cannot be resolved by the sequence data, based on comparisons to outgroup taxa in three other tribes (Oryzomyini, Phyllotini, and Thomasomyini). However, highly corroborated monophyletic units within the group are obtained in a variety of both parsimony and distance analyses. These include a redefined and numerically dominant genus Akodon (with Microxus and Hypsimys as synonyms), Bolomys, Lenoxus, Oxymycterus, and a strongly supported assemblage that includes the central Andean Chroeomys and 'Akodon' andinus and the southern Abrothrix, 'Akodon' olivaceus, and the long-clawed mice of the genera Notiomys, Geoxus, and Chelemys. Sequence divergence within species is typically less than 5%, although levels can reach 10% for some highly polytypic forms. Divergence among genera within the tribe reaches 35% in corrected estimates, a level that is as great as that among representatives of different tribes. Changes in the current classification of akodontines are suggested based on these data, and the timing and place of origin of the tribe and its radiation is discussed.     

Phylogenetic relationships of the Clavelinidae and Pycnoclavellidae (Ascidiacea) inferred from mtDNA data

Abstract. The phylogenetic relationships within the Order Aplousobranchiata (Ascidiacea) are largely unexplored. In this work, we study the phylogenetic status of the genera Clavelina and Pycnoclavella. Traditionally, both genera had been included in the family Clavelinidae, until the new family Pycnoclavellidae was defined, removing the genus Pycnoclavella from Clavelinidae. Not all authors accept the validity of Clavelina and Pycnoclavella as distinct genera, let alone their belonging to different families. In addition, the assignment of species to these genera, as well as to the genus Archidistoma , has been controversial. We analyzed sequences of the mitochondrial gene cytochrome c oxidase subunit I belonging to ten species of Pycnoclavella (including several formerly assigned to Archidistoma and Clavelina ), 11 species of Clavelinidae, and ten species of other aplousobranch genera belonging to seven families, plus two outgroups. Two different tree construction methods (maximum likelihood and Bayesian inference) showed similar results. Pycnoclavella and Clavelina appeared in distinct clades but formed a monophyletic group relative to representatives of the main families of the order Aplousobranchiata. Our phylogenetic results indicate that both genera are valid but should be included within a single family, with the name Clavelinidae having precedence. The monotypic clavelinid genus Nephtheis branches in our trees within the clade of the genus Clavelina. Our results also confirm that some forms assigned to Archidistoma and Clavelina have been misplaced and belong to the genus Pycnoclavella. Pycnoclavella martae n.sp. is described.     

Cladistic analysis of morphological characters in the eulophine tribe Cirrospilini (Hymenoptera: Eulophidae)

A total of 56 morphological characters were analyzed for 53 cirrospiline species that represent all of the 17 described genera of the tribe. The other taxa of the Eulophinae included in the analysis were six species of six representative genera in the tribe Eulophini, a species of Elasmus (the only genus comprising the tribe Elasmini), and a species of Trichospilus (unplaced). Trichospilus and two of the six genera of Eulophini examined were placed within Cirrospilini. Monophyly of Cirrospilini (when these two genera of Eulophini and Trichospilus are included) and of the cirrospiline genera for which more than one species were examined was supported, but the relationships between the genera were poorly resolved. An exception was Cirrospilus, the largest genus in the Cirrospilini, monophyly of which was not supported to any extent.     

Phylogeny of the tribe Abrotrichini (Cricetidae,Sigmodontinae): integrating morphological and molecular evidence into a new classification

The tribe Abrotrichini (five genera and 14 living species) is a small clade within the speciose subfamily Sigmodontinae (Rodentia, Cricetidae), representing one of the extant successful radiations of mammals at southern high latitudes of the Neotropics. Its distribution is mostly Andean, reaching its greatest diversity in southern Argentina and Chile. We evaluate the phylogenetic relationships within this tribe through parsimony and Bayesian approaches based on 99 morphological characters (including 19 integumental characters, 38 skull characters, 31 dental characters, three postcranial skeletal characters, seven from the male accessory glands and phallus and one from the digestive system) and six molecular markers (one mitochondrial and five nuclear). We include representatives of all, except one, of the currently recognized species of living Abrotrichini plus one fossil form. Based on total evidence, we recovered a primary division between the genus Abrothrix and a group including the long‐clawed Abrotrichini, Chelemys, Geoxus, Notiomys and Pearsonomys. Both clades are recognized and named here as subtribes. The large degree of morphological variation observed within Abrothrix suggests that species in the genus fall into four groups, which we recognize as subgenera. In addition, the two known species of Chelemys do not form a monophyletic group, and Geoxus was recovered as paraphyletic with respect to Pearsonomys. To reconcile classification and phylogenetics, we describe a new genus for Chelemys macronyx and include Pearsonomys as a junior synonym of Geoxus. Our results highlight the importance of both morphology and molecules in resolving the phylogenetic relationships within this tribe. Based on biogeographical analyses, we hypothesize that Abrotrichini originated in south‐western South America by vicariance and then diversified mostly by successive dispersal events.     

First phylogeny of predatory flower flies (Diptera, Syrphidae, Syrphinae) using mitochondrial COI and nuclear 28S rRNA genes: conflict and congruence with the current tribal classification

The family Syrphidae (Diptera) is traditionally divided into three subfamilies. The aim of this study was to address the monophyly of the tribes within the subfamily Syrphinae (virtually all with predaceous habits), as well as the phylogenetic placement of particular genera using molecular characters. Sequence data from the mitochondrial protein-coding gene cytochrome c oxidase subunit I ( COI ) and the nuclear 28S ribosomal RNA gene of 98 Syrphinae taxa were analyzed using optimization alignment to explore phylogenetic relationships among included taxa. Volucella pellucens was used as outgroup, and representatives of the tribe Pipizini (Eristalinae), with similar larval feeding mode, were also included. Congruence of our results with current tribal classification of Syrphinae is discussed. Our results include the tribe Toxomerini resolved as monophyletic but placed in a clade with genera Ocyptamus and Eosalpingogaster . Some genera traditionally placed into Syrphini were resolved outside of this tribe, as the sister groups to other tribes or genera. The tribe Bacchini was resolved into several different clades. We recovered Paragini as a monophyletic group, and sister group of the genus Allobaccha . The present results highlight the need of a reclassification of Syrphinae.
© The Willi Hennig Society 2008.     

A phylogeny of four mitochondrial gene regions suggests a revised taxonomy for Asian pitvipers (Trimeresurus and Ovophis)

We present a phylogeny of the Asian pitvipers, based on 2403 bp of four mitochondrial gene regions. All but six known species of Trimeresurus sensu stricto (s.s.) as currently defined, as well as multiple populations of widespread species, which may yet be described as full species, and representatives of all other Asian pitviper genera, are included. Both the greater sampling and larger dataset provide improved resolution over previous studies and support the existence of distinct species groups within Trimeresurus s.s. Although all but two species currently referred to this genus form a monophyletic group, morphological and molecular analyses identify four subgroups that warrant recognition at the generic level. We propose a new generic arrangement to reflect these findings. We also highlight the non-monophyly of Ovophis, and propose a new genus to accommodate a species formerly assigned to Ovophis.     

Tibial combs in the Cydnidae (Hemiptera: Heteroptera) and their functional, taxonomic and phylogenetic significance

Tibial combs in representatives of the family Cydnidae are described in detail for the first time. The structure was studied in 98 species of 58 genera representing all the subfamilies, among them 16 species were investigated using scanning electron microscopic (SEM) techniques. In addition, Parastrachia japonensis (Scott, 1880) of the family Parastrachiidae, and two species of Dismegistus Amyot and Serville, 1843 (a genus of uncertain systematic position within Pentatomoidea) have also been studied. Morphological terminology is proposed for all the structures connected with tibial combs and the term 'the tibial comb complex' is suggested; its functional, taxonomic and phylogenetic significance is also discussed. The genera of Cydnidae can be classified into two groups depending on differences in the tibial comb complex, when it is present; moreover, its absence in the tribe Scaptocorini (Cephalocteinae) is demonstrated for the first time and is regarded as an autapomorphy of this tribe. Data on the occurrence of tibial combs in other families of true bugs (Hemiptera: Heteroptera) are also briefly reviewed, and an anagenetic trend in their evolution in terrestrial Heteroptera is hypothesized. The presence of tibial combs on all legs is regarded as the most plesiomorphic state.     

Chromosome observations of three ranunculaceous genera in relation to their systematic positions

1. The present paper describes the observations of chromosome numbers and karyomorphology of 2 species of 2 endemic genera and I endemic species of Chinese Ranunculaceae: Asteropyrum peltatum (Franch.) Drumm et Hutch. 2n=16, x=8; Kingdonia unifolia Balf. f. et W. W. Sm. 2n=18, x=9 and Calathodes oxycarpa Sprague 2n=16, x=8. The chromosome counts of three ranunculaceous genera are reported for the first time. 2. The morphylogical, palynological and cytological date in relation to the systematic postition of Asteropyrum, Kingdonia and Calathodes within the family Ranunculaceae are diseussed and resulted in following conclusions: (1). On the basis of the basic number x=8 in Asteropyrum, it is further confirmed that this genus is distinct from the r elated genera such as Isopyrum, Dichocarpum and other allied taxa. The comparison of Asteropyrum with Coptis shows that they are identical in short chromosomes, with magnoflorina and benzylisaquinodine type of alkaloides, but different from coptis in the chromosome numbers (T-type), pantocolpate pollens, united carpels and the dorsi-ventral type of petioles. In view of these fundamental morphological and cytological differences, Asterop yrum is better raised to the level of Tribe. However Asteropyrum and Coptis may represent two divaricate evolutional lines of Thalictroideae. (2). The systematic position of the genus Kingdonia has been much disputed in the past. We support the view of Sinnote (1914), namely, the trilacunar in leaf traces “the ancient type”, appeared in the angiosperm line very early, while the unilacunar of Kingdonia may be derived from the trilacunar. On the basis of the chromosome numbers and morphylogical observation, the present writer accept Tamura’s and Wang’s treatment by keeping Kingdonia in Ranunculaceae instead of raising it to a family rank as has been been done by Forster (1961). Kingdonia and Coptis are similar in having short chromosome with x=9, but with one-seeded fruits; therefore it is suggested that placed into Thalictroideae as an independent tribe, indicating its close relationship with Coptideae. (3). Comparing with its allies, Calathodes being with out petals, seems to be more primitive than Trollius. But Calathodes differs from Trollius with R-type chromosomes in having T-type chromosome with x=8 and subterminal centromere. Those characteristics show that it is very similar to the related genera of Thalictroideae. But as Kurita already pointed out that most speci es of Ranunculus have usually large long chromosomes but some species have compar ativelly short chromosomes, therefore we regard T-type and R-type chromosomes appear independently in different subfamilies of Ranunculaceae. According to Tamura, G alathodes seems to be closely related to Megaleranthis, because of the resemblance in follicles. But due to lack of cytological data of the latter genus, the relationship between the two genera still is not clear pending further studies. From the fact that the morphology and chromosomes of the Calathodes differs from that of all other genera of the Helleboroideae, we consider Calathodes may form an independent tribe of its own with a closer relationship withTrollieae.9841     

Phylogeny,classification and evolution of the water scavenger beetle tribe Hydrobiusini inferred from morphology and molecules (Coleoptera: Hydrophilidae: Hydrophilinae)

The water scavenger beetle tribe Hydrobiusini contains 47 species in eight genera distributed worldwide. Most species of the tribe are aquatic, although several species are known to occur in waterfalls or tree mosses. Some members of the tribe are known to communicate via underwater stridulation. While recent morphological and molecular‐based phylogenies have affirmed the monophyly of the tribe as currently circumscribed, doubts remain about the monophyly of included genera. Here we use morphological and molecular data to infer a species‐level phylogeny of the Hydrobiusini. The monophyly of the tribe is decisively supported, as is the monophyly of most genera. The genus Hydrobius was found to be polyphyletic, and as a result the genus Limnohydrobius stat. rev. is removed from synonymy with Hydrobius, yielding three new combinations: L. melaenus comb.n. , L. orientalis comb.n. , and L. tumbius comb.n. Recent changes to the species‐level taxonomy of Hydrobius are reviewed. The morphology of the stridulatory apparatus has undergone a single remarkable transformation within the lineage, from a simple, unmodified pars stridens to one that is highly organized and complex. We present an updated key to genera, revised generic diagnoses and a list of the known distributions for all species within the tribe.     

Phylogenetic systematics of the colorful, cyanide-producing millipedes of Appalachia (Polydesmida, Xystodesmidae, Apheloriini) using a total evidence Bayesian approach

Here, we provide an exemplar-approach phylogeny of the xystodesmid millipede tribe Apheloriini with a focus on genus-group relationships-particularly of the genus Brachoria. Exemplars for the phylogenetic analysis were chosen to represent the maximum breadth of morphological diversity within all nominal genera in the tribe Apheloriini, and to broadly sample the genus Brachoria. In addition, three closely related tribes were used (Rhysodesmini, Nannariini, and Pachydesmini). Morphological and DNA sequence data were scored for Bayesian inference of phylogeny. Phylogenetic analysis resulted in polyphyletic genera Brachoria and Sigmoria, a monophyletic Apheloriini, and a "southern clade" that contains most of the tribal species diversity. We used this phylogeny to track morphological character histories and reconstruct ancestral states using stochastic character mapping. Based on the findings from the character mapping study, the diagnostic feature of the genus Brachoria, the cingulum, evolved independently in two lineages. We compared our phylogeny against prior classifications using Bayes factor hypothesis-testing and found that our phylogenetic hypothesis is inconsistent with the previous hypotheses underlying the most recent classification. With our preferred total-evidence phylogeny as a framework for taxonomic modifications, we describe a new genus, Appalachioria; supply phylogenetic diagnoses of monophyletic taxa; and provide a phylogeny-based classification for the tribe Apheloriini.     

Phylogeny of the bee family Megachilidae (Hymenoptera: Apoidea) based on adult morphology

Phylogenetic relationships within the bee family Megachilidae are poorly understood. The monophyly of the subfamily Fideliinae is questionable, the relationships among the tribes and subtribes in the subfamily Megachilinae are unknown, and some extant genera cannot be placed with certainty at the tribal level. Using a cladistic analysis of adult external morphological characters, we explore the relationships of the eight tribes and two subtribes currently recognised in Megachilidae. Our dataset included 80% of the extant generic‐level diversity, representatives of all fossil taxa, and was analysed using parsimony. We employed 200 characters and selected 7 outgroups and 72 ingroup species of 60 genera, plus 7 species of 4 extinct genera from Baltic amber. Our analysis shows that Fideliinae and the tribes Anthidiini and Osmiini of Megachilinae are paraphyletic; it supports the monophyly of Megachilinae, including the extinct taxa, and the sister group relationship of Lithurgini to the remaining megachilines. The Sub‐Saharan genus Aspidosmia, a rare group with a mixture of osmiine and anthidiine features, is herein removed from Anthidiini and placed in its own tribe, Aspidosmiini, new tribe . Protolithurgini is the sister of Lithurgini, both placed herein in the subfamily Lithurginae; the other extinct taxa, Glyptapina and Ctenoplectrellina, are more basally related among Megachilinae than Osmiini, near Aspidosmia, and are herein treated at the tribal level. Noteriades, a genus presently in the Osmiini, is herein transferred to the Megachilini. Thus, we recognise four subfamilies (Fideliinae, Pararhophitinae, Lithurginae and Megachilinae) and nine tribes in Megachilidae. We briefly discuss the evolutionary history and biogeography of the family, present alternative classifications, and provide a revised key to the extant tribes of Megachilinae.     

Loss of 5S rDNA units in the evolution of Agropyron, Pseudoroegneria, and Douglasdeweya

We have investigated relationships among the three closely related genera Agropyron, Pseudoroegneria, and Douglasdeweya. Based upon grouping of 330 5S rDNA sequences into unit classes, we found that Douglasdeweya, with the genomic constitution PPStSt, has 2 unit classes, the long P1 and short S1, and Pseudoroegneria, with the genomic constitution StSt or StStStSt, has the long S1 and short S1 unit classes. In contrast, only the long P1 unit class was found in species of the genus Agropyron (PP). Having a single unit class is unique among all the genera of the tribe Triticeae investigated so far and may reflect gene loss or lineage sorting during its genesis. The presence of the short S1 and long P1 unit classes confirms the amphiploid origin of Douglasdeweya.     

基于28S rRNA D2序列的内茧蜂亚科的分子系统发育

首次利用同源28S rRNA D2基因序列对内茧蜂亚科Rogadinae （昆虫纲Insecta：膜翅目Hymenoptera：茧蜂科Braconidae）进行了分子系统学研究。本研究从95%～100%乙醇浸渍保存的标本中提取基因组DNA并扩增了10种内群种类和5种外群种类的28S rDNA D2片段并测序（GenBank序列号AY167645-AY167659）,利用BLAST搜索相关的同源序列, 采用了GenBank中13个种类的28S rRNA D2同源序列,然后据此进行分子分析。利用3个外群（共8个种类）和3种建树方法 (距离邻近法distance based neighbor joining, NJ; 最大俭约法maximum parsimony, MP; 和最大似然法maximum likelihood, ML)分析了内茧蜂亚科内的分子系统发育关系。结果表明,由分子数据产生的不同的分子系统树均显示内茧蜂亚科是一个单系群。内茧蜂亚科内依据形态和生物学特征的分群（族和亚族）及其系统发育关系得到部分支持。NJ、MP和ML分析结果均表明内茧蜂族Rogadini不是一个单系,而是一个并系,其余3族则得到不同程度的支持。内茧蜂族可分成2个分支：“脊茧蜂属Aleiodes+弓脉茧蜂属Arcaleiodes”和“沟内茧蜂属Canalirogas+锥齿茧蜂属Conspinaria+刺茧蜂属Spinaria+内茧蜂属Rogas”,二者不是姐妹群。脊茧蜂属Aleiodes和弓脉茧蜂属Arcaleiodes始终是姐妹群。脊茧蜂属Aleiodes是一个单系,并可分成2个姐妹分支,这与依据形态和生物学特征的亚属分群相一致。弓脉茧蜂属Arcaleiodes Chen et He,1991是一个独立的属。分支“沟内茧蜂属Canalirogas+锥齿茧蜂属Conspinaria+刺茧蜂属Spinaria+内茧蜂属Rogas”的单系性仅得到部分分子数据的支持;因形态特异（腹部成甲壳状）而列为亚族级的刺茧蜂属Spinaria,分子分析没有证实这一点。横纹茧蜂族Clinocentrini是个单系,并在内茧蜂亚科的系统发育中处于基部（原始）的位置。我们研究结果还表明,阔跗茧蜂属Yelicones和潜蛾茧蜂属Stiropius相对应的阔跗茧蜂族Yeliconini和潜蛾茧蜂族Stiropiini为2个独立的分支, 与形态和生物学的结果一致,但它们在内茧蜂亚科的系统发育的位置不明,有待今后进一步研究。     

A revision of the tribe Plectrothripini of fungus-feeding Thysanoptera (Phlaeothripidae: Phlaeothripinae)

Abstract The tribe Plectrothripini is redefined with examination of its systematic relationships. Keys are provided to the ten genera and forty-seven species in this tribe; one genus and eighteen species are newly described; one genus and two species are newly synonymized; two genera, Chiridothrips and Eurytrichothrips , are here removed from this tribe. The species of the tribe occur throughout the tropical and subtropical regions of the world; seventeen species are recorded from the Oriental Region, seventeen species from the Neotropical Region, ten species from the Afrotropical Region, two from Australia and one from the Pacific. They seem to be fungus-feeders, being found mainly under the bark of trees or on dead branches.     

A phylogenetic analysis of the fungus-growing ants (Hymenoptera: Formicidae: Attini) based on morphological characters of the larvae

A phylogenetic hypothesis of the fungus-growing ants (subfamily Myrmicinae, tribe Attini) is proposed, based on a cladistic analysis utilizing forty-four morphological characters (109 states) of the prepupal worker larva. The fifty-one attine species analysed include representatives of eleven of the twelve currently recognized attine genera, excluding only the monotypic workerless parasite Pseudoatta ; the non-attines include two outgroups (species of the basal myrmicine genera Myrmica and Pogonomyrmex ), two myrmicine species presumed to be distantly related to the attines, and twelve species representing taxa that have been proposed by prior workers as possible sister groups of the Attini. There is strong character support for the monophyly of the Attini and for a sister-group relationship of the Attini and the Neotropical Blepharidatta brasiliensis. The Attini are divided into two distinct lineages, an 'apterostigmoid' clade (containing Apterostigma and Mycocepurus) and an 'attoid' clade (containing all other attine genera except Myrmicocrypta). The attine genus Myrmicocrypta appears to be paraphyletic with respect to these two groups; the species M.buenzlii in particular retains many attine plesiomorphies.
These results indicate that the fungus-growing behaviour had a single evolutionary origin in the ants. They also indicate that mycelium cultivation is plesiomorphic and that yeast cultivation is derived within the Attini, overturning the long-standing assumption that the yeast-growing Cyphomyrmex species are the most primitive Attini. Behavioural and ecological investigations into the origin and evolution of the fungus-growing behaviour might more profitably focus on species in the attine genus Myrmicocrypta , as well as those in the closely related non-attine genera Blepharidatta and Wasmannia.     

Molecular Systematics and Evolution of Arabidopsis and Arabis

Abstract: We provide a phylogenetic analysis of the genera Arabidopsis and Arabis based on nuclear ribosomal DNA sequences. We show that traditional taxonomical concepts within tribe Ara-bideae, which includes these genera, are highly artificial. Arabis and Arabidopsis are paraphyletic and consist of several different independent lineages. The genus Capsella, originally placed in tribe Lepideae, is related to North American Arabis and the Arabidopsis thaliana lineage. Other genera, including East Asian Yin-shania, North American Halimolobus, cosmopolitan Barbarea and Cardamine, and European Aubrieta are positioned among different Arabis lineages. One Arabis species, Arabis pauciflora, is only distantly related to tribe Arabideae. Base chromosome number reduction from n = 8 to n = 5 to 7 occurred several times, suggesting that lower base chromosome numbers than n = 8 are derived in tribe Arabideae. Current knowledge on the evolution and systematics of the genera Arabis and Arabidopsis and relationships within the mustard family are summarized and discussed in the light of convergent evolution and transfer of knowledge from Arabidopsis thaliana as a molecular model plant to other species of the Cruciferae.