Phylogeny of Decapoda using two nuclear protein-coding genes: origin and evolution of the Reptantia

The phylogeny of Decapoda is contentious and many hypotheses have been proposed based on morphological cladistic analyses. Recent molecular studies, however, yielded contrasting results despite their use of similar data (nuclear and mitochondrial rDNA). Here we present the first application of two nuclear protein-coding genes, phosphoenolpyruvate carboxykinase and sodium-potassium ATPase alpha-subunit, to reconstruct the phylogeny of major infraorders within Decapoda. A total of 64 species representing all infraorders of Pleocyemata were analyzed with five species from Dendrobranchiata as outgroups. Maximum likelihood and Bayesian inference reveal that the Reptantia and all but one infraorder are monophyletic. Thalassinidea, however, is polyphyletic. The nodal support for most of the infraordinal and inter-familial relationships is high. Stenopodidea and Caridea form a clade sister to Reptantia, which comprises two major clades. The first clade, consisting of Astacidea, Achelata, Polychelida and three thalassinidean families (Axiidae, Calocarididae and Eiconaxiidae), corresponds essentially to the old taxon suborder Macrura Reptantia. Polychelida nests within Macrura Reptantia instead of being the most basal reptant as suggested in previous studies. The high level of morphological and genetic divergence of Polychelida from Achelata and Astacidea justifies its infraorder status. The second major reptant clade consists of Anomura, Brachyura and two thalassindean families (Thalassinidae and Upogebiidae). Anomura and Brachyura form Meiura, with moderate support. Notably thalassinidean families are sister to both major reptant clades, suggesting that the stem lineage reptants were thalassinidean-like. Moreover, some families (e.g. Nephropidae, Diogenidae, Paguridae) are paraphyletic, warranting further studies to evaluate their status. The present study ably demonstrates the utility of nuclear protein-coding genes in phylogenetic inference in decapods. The topologies obtained are robust and the two molecular markers are informative across a wide range of taxonomic levels. We propose that nuclear protein-coding genes should constitute core markers for future phylogenetic studies of decapods, especially for higher systematics.     

基于18S rDNA序列的蝽次目(半翅目：异翅亚目)

利用18SrDNA分子约1 912 bp的序列对蝽次目21个科53个种进行系统发育分析。运用MP法、ML法和NJ法分析后的结果表明:蝽次目的单系性得到很高的支持;扁蝽总科成为毛点类的姐妹群;毛点类基本确定为两大分支:一支包含蝽总科和红蝽总科;另一支主要由长蝽总科、缘蝽总科和南蝽总科组成;长蝽总科和缘蝽总科都是多系;长蝽总科中,跷蝽科和皮蝽科的关系最近,构成姐妹群,位于整个毛点类的基部;与长蝽总科中另外两个科长蝽科和地长蝽科的关系很远。说明利用18SrDNA分子对研究蝽次目的系统发育关系是适合的,能够重建蝽次目;扁蝽总科和蝽总科单系性的结果与形态学的研究以及Li et al (2005)的研究一致;但较Li et al(2005)的研究更进一步把红蝽总科从广义的缘蝽总科中分出来;并建议皮蝽科作为一个独立的总科更合适。     

Phylogeny of African monkeys based upon mitochondrial 12S rRNA sequences

The suborder Anthropoidea of the primates has traditionally been divided in three superfamilies: the Hominoidea (apes and humans) and the Cercopithecoidea (Old World monkeys), together comprising the infraorder Catarrhini, and the Ceboidea (New World monkeys) belonging to the infraorder Platyrrhini.We have sequenced an approximately 390-base-pair part of the mitochondrial 12S rRNA gene for 26 species of the major groups of African monkeys and apes and constructed an extensive phylogeny based upon DNA evidence. Not only is this phylogeny of great importance in classification of African guenons, but it also suggests rearrangements in traditional monkey taxonomy and evolution. Baboons and mandrills were found to be not directly related, while we could confirm that the known four superspecies of mangabeys do not form a monophyletic group, but should be separated into two genera, one clustering with baboons and the other with mandrills. Patas monkeys are clearly related to members of the genus Cercopithecus despite their divergence in build and habitat, while the talapoin falls outside the Cercopithecus clade (including the patas monkey). Correspondence to: A.C. van der Kuyl     

Molecular systematics of caridean shrimps based on five nuclear genes: Implications for superfamily classification

Caridean shrimps are the second most diverse group of Decapoda. Over the years, several different systematic classifications, exclusively based on morphology, have been proposed, but the classification of the infraorder Caridea remains unresolved. In this study, five nuclear genes, 18S rRNA, enolase, histone 3, phosphoenolpyruvate carboxykinase and sodium–potassium ATPase α-subunit, were used to examine the systematic status of caridean families and superfamilies. We constructed gene trees based on a combined dataset of 3819 bp, containing 35 caridean species from 19 families in 11 superfamilies. At the family level, and based on our restricted representation, our molecular data support monophyly of the families Glyphocrangonidae, Crangonidae, Pandalidae, Alpheidae, Rhynchocinetidae, Nematocarcinidae, Pasiphaeidae, Atyidae and Stylodactylidae. In contrast, both the Hippolytidae and Palaemonidae are polyphyletic in our analysis. Two major clades are revealed. The Alpheidae, Hippolytidae, Crangonidae, Glyphocrangonidae, Barbouriidae, Pandalidae, Hymenoceridae, Gnathophyllidae and Palaemonidae make up the first clade, while the second clade comprises the Rhynchocinetidae, Oplophoridae, Nematocarcinidae, Alvinocarididae, Campylonotidae, Pasiphaeidae and Eugonatonotidae. Two families, Bathypalaemonellidae and Stylodactylidae, are shown to be basal groups in our tree. At the superfamily level, our results do not support the currently accepted superfamily classification, although there is support for a superfamily Palaemonoidea, though only three out of its eight families are included. The results suggest that the currently accepted superfamily classification of the Caridea does not reflect their evolutionary relationships. A major revision of the higher systematics of Caridea appears thus to be vital, ideally incorporating both molecular and morphological evidence.     

Molecular systematics of the suborder Trogiomorpha (Insecta: Psocodea: 'Psocoptera')

Phylogenetic relationships among extant families in the suborder Trogiomorpha (Insecta: Psocodea: 'Psocoptera') were inferred from partial sequences of the nuclear 18S rDNA and Histone 3 and mitochondrial 16S rDNA genes. Analyses of these data produced trees that largely supported the traditional classification; however, monophyly of the infraorder Psocathropetae (= Psyllipsocidae + Prionoglarididae) was not recovered. Instead, the family Psyllipsocidae was recovered as the sister taxon to the infraorder Atropetae (= Lepidopsocidae + Trogiidae + Psoquillidae), and the Prionoglarididae was recovered as sister to all other families in the suborder. Character states previously used to diagnose Psocathropetae are shown to be plesiomorphic. The sister group relationship between Psyllipsocidae and Atropetae was supported by two morphological apomorphies: the presence of a paraproctal anal spine and an anteriorly opened phallosome. Based on these sequence data and morphological observations, we propose a new classification scheme for the Trogiomorpha as follows: infraorder Prionoglaridetae (Prionoglarididae), infraorder Psyllipsocetae (Psyllipsocidae), infraorder Atropetae (Lepidopsocidae, Trogiidae, Psoquillidae).  © 2006 The Linnean Society of London, Zoological Journal of the Linnean Society , 2006, 146 , 287–299.     

Phylogeny of the true water bugs (Nepomorpha: Hemiptera–Heteroptera) based on 16S and 28S rDNA and morphology

Abstract. Morphological characters and molecular sequence data were for the first time analysed separately and combined for the true water bugs (Hemiptera–Heteroptera, infraorder Nepomorpha). Data from forty species representing all families were included, together with two outgroup species representing the infraorders Gerromorpha and Leptopodomorpha. The morphological data matrix consisted of sixty‐five characters obtained from literature sources. Molecular data included approximately 960 bp from the mitochondrial gene 16S and the nuclear gene 28S for all forty‐two terminal taxa. The morphological dataset was analysed using maximum parsimony and the combined morphological and molecular (16S + 28S rDNA) dataset was analysed using direct optimization. A sensitivity analysis of sixteen different sets of parameters (various combinations of insertion–deletion cost and transversion costs) was undertaken. Character congruence was used as an optimality criterion to choose among competing phylogenetic hypotheses. The final hypothesis was obtained from the analysis of the combined molecular and mor phological dataset with the most congruent parameter set. This hypothesis supports the monophyly of all currently recognized families of Nepomorpha, and of the superfamilies Nepoidea (Nepidae + Belostomatidae), Corixoidea (Corixidae), Ochteroidea Ochteridae + Gelastocoridae), Notonectoidea (Notonectidae), and Pleoidea (Pleidae + Helotrephidae), but not the monophyly of the Naucoroidea (Naucoridae + Aphelocheiridae + Potamocoridae). The close relationship between the Notonectidae and Pleoidea is also supported. Our hypothesis concurs with Mahner in the placement of the Corixidae as a sister group to the remaining nepomorphan superfamilies except the Nepoidea, but differs in the placement of the Ochteroidea as a sister group to the Notonectoidea + Pleoidea. The superfamily Naucoroidea should be limited to only including the family Naucoridae and not the families Aphelocheiridae and Potamocoridae. The present analysis strongly supports a sister group relationship between the families Aphelocheiridae and Potamocoridae, a monophylum for which we propose a new superfamily, Aphelocheiroidea.     

Phylogeny of the infraorder Culicomorpha (Diptera: Nematocera) based on 28S RNA gene sequences

Phylogenetic relationships between the families of the infraorder Culicomorpha were investigated by using partial 28S ribosomal RNA gene sequences. All families traditionally placed in this infraorder were investigated and confirmed as clades. On the other hand, some of the morphological relationships between these families were found to be in disagreement with phylogenies based on molecular characters. Our results did not support the generally accepted division of the Culicomorpha into two superfamilies, the Culicoidea (Culicidae + Corethrellidae + Chaoboridae + Dixidae) and the Chironomoidea (Chironomidae + Ceratopogonidae + Simuliidae + Thaumaleidae). Precisely, if the sister-group relationship between Culicidae, Chaoboridae and Corethrellidae was clearly confirmed, the Dixidae, traditionally considered as closely related to these two families, were not placed close to them on our trees. On the other hand, strong evidence was found for grouping together the Simuliidae and the Thaumaleidae, in spite of the cytological and morphological differences between these two families. The position of the Ceratopogonidae was uncertain, and the Chironomidae appeared as a possible sister group to the rest of Culicomorpha. The phylogenetic positions of the groups characterized by feeding on vertebrate blood or insect haemolymph (the Culicidae, Chaoboridae, Ceratopogonidae and Simuliidae) suggest that haematophagy has appeared at least twice in the evolution of Culicomorpha.     

Phylogeny of parasitiform mites (Acari) based on rRNA

Acari (mites and ticks) form one the most diverse lineages of arthropods, but basal relationships in the group are still poorly understood. The current study addresses this issue for one of its two main lineages, the order Parasitiformes. Relationships are examined at the subordinal and infraordinal level using complete 18S and partial 28S nuclear rRNA sequence data. Most currently recognized lineages are recovered with good support, suggesting that nuclear rRNA, and specifically 18S rRNA, is very well suited for analyzing relationships at this level in this lineage. These results were found despite quite variable rates of sequence evolution, with rates "ratcheting up" from relatively low in most non-mite arachnid lineages, to intermediate in Pseudoscorpiones, the mite order Acariformes, and the parasitiform suborders Opilioacarida, Holothyrida, and Ixodida, to high in the parasitiform suborder Mesostigmata. The most species rich mesostigmatid infraorder, Dermanyssina, shows huge distances to the outgroups, but remarkably low within-group divergence in nuclear rRNA. This suggests the possibility of a relatively recent origin of this lineage.     

Phylogenetic investigations of the stephanoberyciformes and beryciformes, particularly whalefishes (Euteleostei: Cetomimidae), based on partial 12S rDNA and 16S rDNA sequences

DNA data were collected from a number of acanthomorph fishes for 12S rDNA (30 sequences) and 16S rDNA (39 sequences) to investigate the phylogenetic relationships of genera within Cetomimidae (whalefishes) and of this family within the Stephanoberyciformes/Beryciformes assemblage. The Cetomimidae are apparently monophyletic. Within the family, species of Gyrinomimus and Cetomimus form a clade but the former genus is paraphyletic with respect to the latter. Cetostoma is sister to Ditropichthys rather than to Gyrinomimus plus Cetomimus as suggested by morphological analyses. Rondeletiidae + Cetomimidae + Barbourisiidae are shown, as expected from morphological analyses, as a monophyletic group in the 12S rDNA analyses, but not in the 16S rDNA or combined analyses, although the shortest trees showing the group require only one extra step in each case. These three families plus Melamphaidae (our sample of Stephanoberyciformes) are not shown as a group in any analysis, with Melamphaidae being sister to Berycidae in the 16S and combined analyses, but dispersed in the 12S analyses. Maximum-parsimony trees without imposed constraints are notably shorter than trees constrained to show ordinal groupings or either of the two main current hypotheses of Stephanoberyciformes/Beryciformes relationships. The length difference is highly significant for most comparisons using either 12S or 16S rDNA sets or their combination, and significant or nearly so for all comparisons. In particular, the Beryciformes is unlikely to be monophyletic. The Holocentridae are included, with high bootstrap and Bremer support, in a clade of non-beryciforms comprising the Gempylidae, Zeidae, and Atheriniformes (the only higher acanthomorphs sampled) and not with other Beryciform families. In these data, the Berycidae are the sister to the Melamphaidae, a stephanoberyciform family.     

Filling the gaps in the classification of the Digenea Carus, 1863: systematic position of the Proterodiplostomidae Dubois, 1936 within the superfamily Diplostomoidea Poirier, 1886, inferred from nuclear and mitochondrial DNA sequences

The Diplostomida Olson, Cribb, Tkach, Bray & Littlewood, 2003 is the less diverse order of the two orders within the subclass Digenea Carus, 1863 and is currently classified into three superfamilies, i.e. Brachylaimoidea Joyeux & Foley, 1930, Diplostomoidea Poirier, 1886, and Schistosomatoidea Stiles & Hassall, 1898. Although the suprageneric-level relationships have been elucidated with the use of molecular markers, the lack of representation of some groups obscure the phylogenetic relationships among families, rendering the classification unstable. Here, we tested the phylogenetic position of the family Proterodiplostomidae Dubois, 1936 based on partial 28S rDNA and complete 18S rDNA sequences for Crocodilicola pseudostoma (Willemoes-Suhm, 1870), a crocodile parasite that has been found as a progenetic metacercaria parasitising the pale catfish Rhamdia guatemalensis (Günther) in Mexico and in other siluruforms in the Neotropics. We augmented the representation of the species, genera and families within the Diplostomida, including mostly representatives of the superfamily Diplostomoidea, and assembled a dataset that contains 49 species for the 28S rRNA gene, and 45 species for the 18S rRNA gene. Additionally, we explored the phylogenetic signal of the mitochondrial gene cox1 in reconstructing the phylogenetic relationships of selected members of the superfamily. Our analyses showed that the family Proterodiplostomidae is the sister taxon to the paraphyletic Diplostomidae Poirier, 1886 and Strigeidae Railliet, 1919, with Cyathocotylidae Mühling, 1898 + Brauninidae Wolf, 1903 as their sister group. Analysis of concatenated 18S + 28S sequences revealed the Liolopidae Odhner, 1912 as the basal group of the superfamily Diplostomoidea, although analyses of independent datasets showed that the position of this family remains uncertain. Analysis based on cox1 unequivocally resolved the Proterodiplostomidae as the sister taxon to the Diplostomidae and Strigeidae, although the Cyathocotylidae was nested in a different clade, along with brachylaimoids and schistosomatoids.     

The complete mitochondrial genome of the Japanese mud shrimp Upogebia major (Crustacea, Decapoda)

We determined a full-length sequence of mitochondrial (mt) genome from Upogebia major. This is the first complete mt genome report for infraorder Thalassinidea in Decapoda, Crustacea. Our result showed that U. major generally followed a typical pancrustacean gene order but some tRNA genes showed a very unique gene arrangement such as duplication or translocation. Since none of the complete mt genome sequences in the infraorder Thalassinidea are available yet, this report will provide additional information in relation to mt genome diversity and evolution of the decapods.     

A phylogenetic study of the 'bombycoid complex' (Lepidoptera) using five protein-coding nuclear genes, with comments on the problem of macrolepidopteran phylogeny

Abstract This study had two aims. First, we tested the monophyly of and relationships within the ‘bombycoid complex’, an assembly of approximately 5300 species postulated by Minet to represent 12 families in three superfamilies, by sequencing five protein‐coding nuclear gene regions (CAD, DDC, enolase, period, wingless; approximately 6750 bp total) in 66 representatives of most of the subfamilies and tribes. Second, we sought initial evidence on the utility of these genes for estimating relationships among Macrolepidoptera more broadly (11 superfamilies total), by adding representatives of eight families from four other superfamilies, and by assessing the phylogenetic information content of the individual genes and partitions thereof. Analysis of the combined data by likelihood and parsimony upholds monophyly for the bombycoid complex and for Bombycoidea sensu stricto (includes Anthelidae, see below), but with weak bootstrap support. Minet’s assignment of Phiditiinae to Bombycoidea rather than to Noctuoidea is strongly upheld, but Anthelidae, placed in Lasiocampoidea by Minet, group securely within Bombycoidea sensu stricto. Within the latter, the basal split segregates a strongly supported ‘BALE’ group [Apatelodinae + (Eupterotidae + (Brahmaeidae + Lemoniidae))]. The remaining families form a consistently but weakly supported clade, within which the basal split segregates the very strongly supported ‘CAPOPEM’ group [Carthaeidae, Anthelidae, Phiditiinae, (Prismostictini + (Endromidae + (Oberthueriini + Mirinidae)))]. The remaining bombycoids are grouped, very weakly, as Sphingidae + (Bombycinae + Saturniidae). All multiply‐sampled families are strongly recovered, in both outgroups and ingroups, except that Bombycidae sensu Minet are rendered decisively polyphyletic. All genes make important contributions to the combined data results, and there is little strong conflict among genes or between synonymous and nonsynonymous change, although two instances of inter‐gene conflict were notable, one in Lasiocampidae and one in Mimallonidae. Overall, about 75% of nodes are strongly supported (i.e. bootstrap value ≥80%). Superfamilies are recovered, but not always strongly, whereas relationships among superfamilies are recovered only weakly and inconsistently; even within the reasonably well‐sampled Bombycoidea sensu stricto, a (to us) surprising number of interfamily relationships remain uncertain. Thus, it seems clear that substantially more genes, plus additional taxon sampling in most superfamilies, will be required to resolve macrolepidopteran phylogeny.     

淡水豚类线粒体DNA 12S rRNA基因的序列变异及其分子系统学研究

淡水豚类４个代表属「白暨豚（Ｌｉｐｏｔｅｓ）、恒河豚（Ｐｌａｔａｎｉｓｔａ）、弗西豚（Ｐｏｎｔｏｐｏｒｉａ）和亚河豚（Ｉｎｉａ）」ｍｔＤＮＡ １２Ｓ ｒＲＮＡ基因的序列差异水平,高于其他齿鲸类科间的差异,特别是远远高于海豚总科内的科间差异。研究结果支持它们应归属于不同的科,即白暨豚科（Ｌｉｐｏｔｉｉｄａｅ）、恒河豚科（Ｐｌａｔａｎｉｓｔｉｄａｅ）、弗西豚科（Ｐｏｎｔｏｐｏｒｉｄａｅ）和亚河豚科（Ｉ     

从16S rRNA基因序列初步探讨拟壁钱属和壁钱属蜘蛛系统发生关系

拟壁钱属Oecobius和壁钱属Uroctea蜘蛛之间系统发生关系存在一定的争议.为从分子水平探讨两属间系统发生关系,本研究测定了5科6种蜘蛛的16S rRNA基因部分序列,并联合来自GenBank的8科8种蜘蛛16S rRNA基因序列数据重建分子系统树.结果表明,拟壁钱属和壁钱属间遗传距离(28.1%)明显大于复杂生殖器类(Entelegynae)蜘蛛属间遗传距离的平均值(22.9%);与目前大多数文献把拟壁钱属和壁钱属并在一个科的观点相反,本研究重建的系统发生树显示两属不是姊妹群.作者建议把拟壁钱属和壁钱属分别重新划回拟壁钱科Oecobiidae和壁钱科Urocteidae.系统发生树还验证了简单生殖器类(Haplogynae)蜘蛛、复杂生殖器类蜘蛛各自的单系性以及筛器类(Cribellate)蜘蛛的多系发生,同时本文的结果还对圆网蛛类(Orbiclariae)单系发生及RTA类群单系发生的有效性提出了质疑.     

Phylogeny of the Platyhelminthes and the evolution of parasitism

Robust phylogenies provide the basis for interpreting biological variation in the light of evolution. Homologous features provide phylogenetically informative characters whereas homoplasious characters provide phylogenetic noise. Both provide evolutionary signal. We have constructed molecular and morphologically based phylogenies of the phylum Platyhelminthes using a recently revised morphological character matrix and complete 18S and two partial 28S rRNA gene sequences in order to evaluate the emergence and subsequent divergence of parasitic forms. In total we examine 65 morphological characters, 97 18S rDNA, 41 Dl domain 28S rDNA, and 49 D3-D6 domain 28S rDNA sequences. For the molecular data there were 748, 132 and 249 phylogenetically informative sites for the 18S, Dl and D3-D6 28S rDNA data sets respectively. Morphological and molecular phylogenetic solutions are incongruent but not incompatible, and using the principles of conditional combination (18S rDNA + morphology passing Templeton's test) they demonstrate: a single and relatively early origin for the parasitic Neodermata (including the cestodes, trematodes and monogeneans); sister-group status between the cestodes and monogeneans, and between these taxa and the trematodes (digeneans and aspidogastreans). The sister-group to the Neodermata is likely to be a large clade of neoophoran turbellarians, based on combined evidence, or a clade consisting of the Fecampiid + Urastomid turbellarians, based on morphological evidence alone. The combined evidence solution for the phylogeny of fiatworms based on 18S rDNA and morphology is used to interpret morphological and life-history data and to support a model for the evolution and radiation of neodermatan parasites in the group.     

Comparative studies of the branchial morphology, gill area and gill ultrastructure of some thalassinidean mud-shrimps (Crustacea: Decapoda: Thalassinidea)

The morphology, gill area and branchial formulae of six thalassinidean decapods ( Calocaris macandreae, Jaxea nocturna, Callianassa subterranea, Upogebia stellata, U. deltaura and U. pusilla ) are reported. Additionally, the rarely-encountered Axius stirhynchus receives brief attention. Gill formulae are presented; the simplest arrangements are found in the Callianassidae and Upogebiidae. The deeper-burrowing, deposit-feeding species that are regularly exposed to prolonged periods of hypoxia, i.e. Callianassa subterranea and Jaxea nocturna , had significantly larger gill areas than thalassinideans that occupied more oxygenated burrows ( Upogebia spp., Calocaris macandreae ). The increase in gill area was a result of flattening of the trichobranchiate gill filaments giving rise to a phylloid gill form. It is suggested that the efficiency of gas transfer, and hence diffusing capacity, was enhanced in the phylloid gill by the larger gill area and, because of the reduced cuticle thickness, by the shorter water-haemolymph diffusion distance. The increased diffusion capacity of the phylloid gill is interpreted as a functional adaptation to the more severe physicochemical burrow water conditions experienced by Callianassa subterranea and Jaxea nocturna .     

从线粒体基因探讨中国大头蛙群的分类及其属内地位

Partial sequences of the mitochondrial 12S rRNA and 16S rRNA gene were determined for 8 populations of three species of Chinese Limnonectes, and aligned with the published sequences of Limnonectes from other parts of the world. When Nanorana parker, Paa boulengeri, Fejervarya limnocharis and Hoplobatrachus rugulosus was used as outgroup taxa (Accession Nos. AY158705, AY313685, AF206111, AF206491, AY322311). The sequences of the 12S rRNA and 16S rRNA genes totaled 950 nueleotide positions with gaps including 510 variable sites. We reconstructed phylogenetie trees using Clustal X 1.8, Mega 2.1 and PHYLIP 3.5e software, and using the maximum parsimony and maximum likelihood methods, respectively. Our analyses suggest that these fanged frogs from China are another monophyletie group in addition to the four monophyletie groups identified by previous studies. The Chinese Limnonectes were grouped into three elades (BCL 55% ). The first elade contains one species (BCL 100% ), from a population of Limnoneetes fragilis from Hainan Province. The second contains four individuals (BCL 100% ), i. e. two populations of Limnonectes kuhlii from Yunnan Province. The third contains one species (BCL 100% ), i. e. five populations of Limnonectes fujianensis from Fujian Province and 1 from Taiwan Province. The resulted phylogenetie trees indicate L. fragilis is basal to L. kuhlii L. fujianensis 。