The phylogeny of land plants inferred from 18S rDNA sequences: pushing the limits of rDNA signal?

Previous studies of the phylogeny of land plants based on analysis of 18S ribosomal DNA (rDNA) sequences have generally found weak support for the relationships recovered and at least some obviously spurious relationships, resulting in equivocal inferences of land plant phylogeny. We hypothesized that greater sampling of both characters and taxa would improve inferences of land plant phylogeny based on 18S rDNA sequences. We therefore conducted a phylogenetic analysis of complete (or nearly complete) 18S rDNA sequences for 93 species of land plants and 7 green algal relatives. Parsimony analyses with equal weighting of characters and characters state changes and parsimony analyses weighting (1) stem bases half as much as loop bases and (2) transitions half as much as transversions did not produce substantially different topologies. Although the general structure of the shortest trees is consistent with most hypotheses of land plant phylogeny, several relationships, particularly among major groups of land plants, appear spurious. Increased character and taxon sampling did not substantially improve the performance of 18S rDNA in phylogenetic analyses of land plants, nor did analyses designed to accommodate variation in evolutionary rates among sites. The rate and pattern of 18S rDNA evolution across land plants may limit the usefulness of this gene for phylogeny reconstruction at deep levels of plant phylogeny. We conclude that the mosaic structure of 18S rDNA, consisting of highly conserved and highly variable regions, may contain historical signal at two levels. Rapidly evolving regions are informative for relatively recent divergences (e.g., within angiosperms, seed plants, and ferns), but homoplasy at these sites makes it difficult to resolve relationships among these groups. At deeper levels, changes in the highly conserved regions of small-subunit rDNAs provide signal across all of life. Because constraints imposed by the secondary structure of the rRNA may affect the phylogenetic information content of 18S rDNA, we suggest that 18S rDNA sequences be combined with other data and that methods of analysis be employed to accommodate these differences in evolutionary patterns, particularly across deep divergences in the tree of life.     

Genus Tetrastemma Ehrenberg, 1831 (Phylum Nemertea)--a natural group? Phylogenetic relationships inferred from partial 18S rRNA sequences

We investigated the monophyletic status of the hoplonemertean taxon Tetrastemma by reconstructing the phylogeny for 22 specimens assigned to this genus, together with another 25 specimens from closely related hoplonemertean genera. The phylogeny was based on partial 18S rRNA sequences using Bayesian and maximum likelihood analyses. The included Tetrastemma-species formed a well-supported clade, although the within-taxon relationships were unsettled. We conclude that the name Tetrastemma refers to a monophyletic taxon, but that it cannot be defined by morphological synapomorphies, and our results do not imply that all the over 100 species assigned to this genus belong to it. The results furthermore indicate that the genera Amphiporus and Emplectonema are non-monophyletic.     

Phylogenetic relationships of true butterflies (Lepidoptera: Papilionoidea) inferred from COI, 16S rRNA and EF-1α sequences

The molecular phylogenetic relationships among true butterfly families (superfamily Papilionoidea) have been a matter of substantial controversy; this debate has led to several competing hypotheses. Two of the most compelling of those hypotheses involve the relationships of (Nymphalidae + Lycaenidae) + (Pieridae + Papilionidae) and (((Nymphalidae + Lycaenidae) + Pieridae) + Papilionidae). In this study, approximately 3,500 nucleotide sequences from cytochrome oxidase subunit I (COI), 16S ribosomal RNA (16S rRNA), and elongation factor-1 alpha (EF-1α) were sequenced from 83 species belonging to four true butterfly families, along with those of three outgroup species belonging to three lepidopteran superfamilies. These sequences were subjected to phylogenetic reconstruction via Bayesian Inference (BI), Maximum Likelihood (ML), and Maximum Parsimony (MP) algorithms. The monophyletic Pieridae and monophyletic Papilionidae evidenced good recovery in all analyses, but in some analyses, the monophylies of the Lycaenidae and Nymphalidae were hampered by the inclusion of single species of the lycaenid subfamily Miletinae and the nymphalid subfamily Danainae. Excluding those singletons, all phylogenetic analyses among the four true butterfly families clearly identified the Nymphalidae as the sister to the Lycaenidae and identified this group as a sister to the Pieridae, with the Papilionidae identified as the most basal linage to the true butterfly, thus supporting the hypothesis: (Papilionidae + (Pieridae + (Nymphalidae + Lycaenidae))).     

Review of records of hymenolepidids (Eucestoda: Hymenolepididae) from dormice (Rodentia: Gliridae) in Europe,with a redescription of Armadolepis spasskyi Tenora & Baruš, 1958 and the description of A. genovi n. sp.

Systematic Parasitology - Armadolepis (Armadolepis) spasskyi Tenora & Baru?, 1958 is redescribed on the basis of the type-series consisting of the holotype from the garden dormouse...     

Neophilometroides n. gen. (Nematoda: Philometridae) for Philometroides caudatus Moravec,Scholz and Vivas-Rodríguez, 1995, with erection of Neophilometroidinae n. subfam

A detailed examination (including scanning electron microscopy) of newly collected nematode specimens (subgravid females) referable to Philometroides caudatus Moravec, Scholz and Vivas-Rodríguez, 1995, from the swimbladder of the pimelodid catfish, Rhamdia guatemalensis, in the Papaloapan River in Tlacotalpan, State of Veracruz, Mexico, as well as the paratype specimens of this species, revealed the presence of a small buccal capsule armed with peribuccal teeth in the female. Because of this unique morphological feature within the Philometridae, and considering other taxonomically important characters such as the structure of the male tail and the shape of the anterior end of the esophagus in the gravid female, Neophilometroidinae n. subfam, and Neophilometroides n. gen. are proposed to accommodate this species. Philometra paraguayensis Petter, 1995, is transferred to Neophilometroides as N. paraguayensis (Petter, 1995) n. comb. Newly collected specimens are briefly described and illustrated.     

Wallinia chavarriae n. sp. (Trematoda: Macroderoididae) in Astyanax aeneus (Gunther, 1860) and Bryconamericus scleroparius (Regan, 1908) (Osteichthyes: Characidae) from the Area de Conservación Guanacaste,Costa Rica

Wallinia chavarriae n. sp. is described from the small-bodied characids Astyanax aeneus and Bryconamericus scleroparius in the Area de Conservación Guanacaste, northwestern Costa Rica. The species differs from W. valenciae in possessing an acetabulum that is smaller than the oral sucker and vitelline follicles that are ovoid or rounded rather than elongate and tubular. Detailed comparison between these 2 species is handicapped by the less than satisfactory condition of the type and only museum specimen of W. valenciae. Wallinia chavarriae and W. valenciae belong to a subfamily of trematodes, Walliniinae, that arguably includes Creptotrematina spp., Magnivitellum simplex, and possibly Margotrema. The morphology of walliniines suggests that they are macroderoidids, but a clearer understanding of their classification could be gained from their larval morphology or from molecular systematic studies. The host associations of a monophyletic Walliniinae would indicate diversification within 2 groups of freshwater fishes: the neotropical characids for species of Wallinia, Creptotrematina, and Magnivitellum and the endemic central Mexican goodeids for those of Margotrema. The biogeography and host associations of these parasites provide a system for studies of potential host switching and vicariance, involving the middle-American and neotropical regions.     

Poecilorhynchus perplexus n. g., n. sp. (Trypanorhyncha: Eutetrarhynchidae) from the brownbanded bambooshark, Chiloscyllium punctatum Müller & Henle, from Australia

A new genus of trypanorhynch cestodes is described from the brownbanded bambooshark, Chiloscyllium punctatum Müller & Henle (Hemiscylliidae) from off Nickol Bay, Western Australia. Poecilorhynchus perplexus n. g., n. sp. is placed in the Eutetrarhynchidae Guiart, 1927 because it is characterised by an elongate, acraspedote scolex with two oval bothria, the absence of bothrial pits, elongate bulbs, the presence of gland-cells within the bulbs and prebulbar organs, retractor muscles inserting at the base of each bulb and an acraspedote strobila. It can be distinguished from all other genera in this family by its possession of a poeciloacanthous typical armature, with a chainette composed of two longitudinal files of uncinate hooks on the external tentacular surface.     

Phlebotomine sandflies (Diptera: Psychodidae) from Lábrea,state of Amazonas,Brazil, with a description of Evandromyia (Aldamyia) apurinan Shimabukuro,Figueira & Silva,sp. nov.

An entomological survey was conducted from July-December 2009 and September-December 2010, as part of the epidemiological monitoring of American cutaneous leishmaniasis (ACL) in the municipality of Lábrea, state of Amazonas (AM), Brazil. Sandflies were collected using CDC light traps installed in intra and peridomiciliary locations, as well as the border of forested areas around houses where autochthonous cases of ACL were recorded. A total of 510 sandflies belonging to 26 species were collected. The most abundant species was Nyssomyia antunesi (44.5%) followed by Evandromyia walkeri (10.6%) and Micropygomyia rorotaensis (9.8%). Here we also describe Evandromyia (Aldamyia) apurinan sp. nov. and report new records for Trichophoromyia flochi and Evandromyia sipani in AM and Brazil, respectively. Our results describe the composition of the sandfly fauna in the south of AM and suggest Ny. antunesi as the putative vector in the transmission of Leishmania in this area of the Amazon Region.     

Genetic relationships among species of Contracaecum Railliet & Henry, 1912 and Phocascaris Höst, 1932 (Nematoda: Anisakidae) from pinnipeds inferred from mitochondrial cox2 sequences, and congruence with allozyme data

The genetic relationships among 11 taxa, belonging to the genus Contracaecum (C. osculatum A, C. osculatum B, C. osculatum (s.s.), C. osculatum D, C. osculatum E, C. osculatum baicalensis, C. mirounga, C. radiatum, C. ogmorhini (s.s.), C. margolisi) and Phocascoris (Phocoscris cystophorae), parasites as adults of seals, were inferred from sequence analysis 1519 bp) of the mitochondrial cytochrome c oxidase subunit II (mtDNA cox2) gene. Phylogenetic analyses obtained from Parsimony (MP) and Neighbour-Joining (NJ) K2P distance values generated similar topologies, each well supported at major nodes. All analyses delineated two main clades: the first encompassing the parasites of the phocid seals, i.e. the C. osculatum species complex, C. osculatum boicolensis, C. mirounga and C. radiatum, with the latter two species forming a separate subclade; the second including the parasites of otarids, i.e. C. ogmorhini (s.s.) and C. margolisi. An overall high congruence between mtDNA inferred tree topologies and those produced from nuclear data sets (20 allozyme loci) was observed. Comparison of the phylogenetic hypothesis here produced for Controcaecum spp. plus Phocascaris with those currently available for their definitive hosts (pinnipeds) suggests parallelism between hosts and parasite phylogenetic tree topologies.     

A new variety of Senecio (Asteraceae: Senecioneae) from the Sierra de Manantlán,Jalisco, Mexico,with notes on the S. roldana complex

Senecio galicianus var.manantlanensis (sectionPalmatinervii) occurs in cooler, moister habitats at higher elevations of the Sierra de Manantlán than the typical variety. Morphological, ecological, and phenological data support maintainingS. galicianus andS. Kerberi as species separate from the closely relatedS. Roldana and treating the new taxon as a variety ofS. galicianus. Although var.manantlanensis tends to have larger and less deeply and sharply lobed leaves than var.galicianus,t-tests and discriminant analyses demonstrate that the best diagnostic characters are the fewer but longer phyllaries and florets in its heads.     

Paracreptotrema profundulusi n. sp. and P. blancoi Choudhury, Pérez-Ponce De León, Brooks, and Daverdin, 2006 (Trematoda: Allocreadiidae) from freshwater fishes of the genus Profundulus (Teleostei: Profundulidae) in southern México

Paracreptotrema profundulusi n. sp. (Trematoda: Allocreadiidae) is described from the intestine of the freshwater fishes Profundulus punctatus and P. balsanus (Teleostei: Profundulidae) from the Tehuantepec and the Atoyac-Verde River basins, in Oaxaca, México, in the western extreme of Central America. The new species is distinguished from Paracreptotrema blancoi Choudhury, Pérez-Ponce de León, Brooks, and Daverdin, 2006 , to which it is most similar, and from P. mendezi (Sogandares-Bernal, 1955) Choudhury, Pérez-Ponce de León, Brooks, and Daverdin, 2006 , by the caeca extending beyond the testes, vitelline follicles that invade the postesticular area, and uterus with transverse loops located mainly between the testes and the genital pore. Paracreptotrema blancoi was collected from the same host species and also from Profundulus oaxacae. Here, we provide data that show its broad distribution in several river basins of Neotropical southern México, including the Papagayo River basin, Guerrero, México, and the Atoyac-Verde and Tehuantepec river basins, and other rivers in Oaxaca, México. Freshwater fishes of the Profundulidae are endemic to Central America and host a helminth fauna that includes at least 4 species found only in these hosts.     

Aporocotyle mariachristinae n. sp., and A. ymakara Villalba & Fernández, 1986 (Digenea: Aporocotylidae) of the pink cusk-eel,Genypterus blacodes (Ophidiiformes: Ophidiidae) from Patagonia,Argentina

Aporocotyle mariachristinae n. sp. and A. ymakara Villalba & Fernández, 1986 were collected from the bulbus arteriosus and ventral aorta of pink cusk-eels, Genypterus blacodes (Forster, 1801) from Patagonia, Argentina. A. mariachristinae n. sp. can be distinguished from all the species of Aporocotyle by the asymmetrical extension of posterior caeca (right posterior caecum longer, terminating at the area between mid-level of ovary and posterior body end; left posterior caecum shorter, terminating at the area between mid-level of cirrus sac and posterior to reproductive organs), the distribution of spines along the ventro-lateral body margins and the number of testes. The new species clearly differs from A. ymakara, from the same host species, in the esophagus / body length ratio, the absence of distal loops at caeca, the anterior caeca / posterior caeca length ratio, and the number of testes. Additionally, in A. ymakara the left posterior caecum may be longer than right posterior caecum, while in the new species left posterior caecum is always shorter. The specimen of A. ymakara collected from Argentina is also described. We also provide observations of the distribution of spines in different species of Aporocotyle, including new specimens of A. argentinensis Smith, 1969 from Merluccius hubbsi Marini, 1933. Molecular sequence data obtained from partial 18S and 28S rDNA regions were compared between the new species and other two species of Aporocotyle (A. argentinensis and A. spinosicanalis Williams, 1958). This is a new locality record for A. ymakara, extending the known geographical distribution for this species from Chile to Argentina, and the first report of two species of Aporocotyle in the same host species and locality.     

Morphogenesis in the marine spirotrichous ciliate Apokeronopsis crassa (Claparède & Lachmann, 1858) n. comb. (Ciliophora: Stichotrichia), with the establishment of a new genus, Apokeronopsis n. g., and redefinition of the genus Thigmokeronopsis

Morphogenetic events during the division of the marine spirotrichous ciliate, Apokeronopsis crassa (Claparède & Lachmann 1858) n. comb. were investigated. Compared with members of the well-known genera Thigmokeronopsis, Uroleptopsis, and Pseudokeronopsis, A. crassa has one row of buccal cirri, high number of transverse cirri, clearly separated midventral rows, lacks thigmotactic cirri and a gap in adoral zone, its undulating membranes (UMs) anlage forms one cirrus and marginal rows and dorsal kineties form apokinetally during division. All these characteristics indicate that this organism represents a new taxon at the generic level, and hence a new genus is suggested, Apokeronopsis n. g. It is defined as thus: Pseudokeronopsidae with Pseudokeronopsis-like bicorona of frontal cirri and one marginal row on each side; one row of two or more buccal cirri in ordinary position; two midventral rows distinctly separated, hence of cirri that are not in a typical zig-zag pattern; high number of transverse cirri, caudal cirri absent, and frontoterminal cirri present; thigmotactic cirri absent, many macronuclear nodules fuse into many masses as well as marginal and dorsal kineties form apokinetally during morphogenesis. At the same time, the genus ThigmokeronopsisWicklow, 1981 is redefined, and one new combination, Apokeronopsis antarctica (Petz, 1995) n. comb. is proposed. The morphogenetic events of A. crassa are characterized as follows: (1) In the proter, the adoral zone of membranelles and UMs are completely renewed by the oral primordium. The UM anlage is formed apokinetally on the dorsal wall of the buccal cavity and is hence clearly separated from the frontoventral-transverse (FVT) cirral anlagen in the proter. (2) Frontoventral-transverse cirral anlagen are generated de novo in the outermost region of the cortex to the right of the old UMs. (3) A row of buccal cirri arises from FVT cirral streak I. (4) The marginal rows and dorsal kineties originate de novo in both dividers; no caudal cirri are formed. (5) The last FVT-streak contributes two frontoterminal cirri. (6) The many macronuclear nodules fuse into many masses (about 50 segments) during division, unlike a singular or branched mass as described in other urostylids.