Received: 21 March 2002 / Accepted: 07 August 2002
Phylogenetic and biosystematic relationships in four highly disjunct polyploid complexes in the subgenera Ceterach and Phyllitis in Asplenium (Aspleniaceae)Download PDFAbstract
Phylogenetic studies using DNA sequences of two chloroplast regions, rbcL and trnL-F, demonstrate that the proposed genus Ceterach is a small clade within the large genus Asplenium, and sister to the Phyllitis clade. The Ceterach clade is characterised by irregular anastomosing veins and often densely scaled leaf blades. Its taxonomic status as a group nested within Asplenium is confirmed, and it is accepted here as a subgenus with seven species. The Ceterach clade comprises four lineages that correspond to disjunct polyploid complexes: the A. aureum clade forming a polyploid complex (4×, 6×, 8×) in Macaronesia, the A. ceterach clade forming a polyploid complex (2×, 4×, 6×) in the Mediterranean Basin, the A. paucivenosum clade (4×, 6×) in central Asia, and the A. dalhousiae clade (2×) with a disjunct distribution in the Himalaya, Yemen and Eritrea, and southwestern North America. Asplenium paucivenosum is sister to all other members of the Ceterach clade, whereas A. dalhousiae is sister to the A. aureum clade that includes tetraploid A. aureum, hexaploid A. lolegnamense, and octoploid A. parvifolium. Asplenium ceterach and its variations – including the hexaploid A. ceterach subsp. mediterraneum subsp. nov. first described below – form a monophyletic unit, sister to a clade consisting of A. aureum and A. dalhousiae. Asplenium cordatum from Africa and A. haugthonii from the isolated atlantic island of St. Helena are not members of the Ceterach clade, which suggests that leaf blades with dense indumenta have evolved at least twice within asplenioid ferns. The allotetraploid species A. hybridum has the chloroplast DNA from A. ceterach, and therefore the latter species is the maternal ancestor of the former. The other parent of this hybrid species is A. sagittatum that is nested within the sister clade of Ceterach, the Phyllitis clade comprising A. sagittatum and A. scolopendrium. The findings suggest that the current distribution of Ceterach is either the result of long-distance dispersal or represents fragmented relicts of a previously more widely distributed species.
Received: 28 August 2001 / Accepted: 25 January 2002
Heavy infestation by endoparasitic copepod crustaceans (Poecilostomatoida: Splanchnotrophidae) in Chilean opisthobranch gastropods, with aspects of splanchnotrophid evolutionDownload PDFAbstract
Copepods of the family Splanchnotrophidae are very significant parasites of shell-less opisthobranchs, but little information exists on their occurrence, infection frequencies, and local or seasonal abundances. Using a quantitative faunistic approach, 2257 potential hosts belonging to 47 opisthobranch species were collected from 1991 to 1996 off the Chilean and Argentinian coasts, mainly by SCUBA. Endoparasitic splanchnotrophids of the genus Ismaila were found in 303 host specimens, corresponding to a 13% prevalence of infection. The opisthobranch hosts were one sacoglossan, three doridoidean and four aeolidoidean nudibranch species. In total, 12 Chilean opisthobranch species are known to be infected with splanchnotrophids. This amounts to about 20% of all shell-less opisthobranch species from Chile, and a remarkable 26% of all splanchnotrophid hosts worldwide. Infection frequencies are low in most host species, but reached 89–100% in certain populations of Thecacera darwini, Okenia luna, Flabellina sp. 1 and Elysia patagonica, representing the highest rates of infestation by splanchnotrophids ever documented. In Thecacera darwini, the prevalence was very low in northern Chile, consistently high in central Chile, and low in the south. High infestation coupled with a high number of sympatric but host-specific species indicate the coast of central Chile is a centre of Ismaila evolution. The biogeography of splanchnotrophid genera is discussed, and a hypothesis on their distributional history is presented.See also Electronic Supplement (Parts 1 and 2) at http://www.senckenberg.de/odes/02-03.htm
Received: 04 October 2001 / Accepted: 15 December 2001
On abyssal isopods (Crustacea: Isopoda: Asellota) from the Angola Basin: Eurycope tumidicarpus n. sp. and redescription of Acanthocope galathea Wolff, 1962Download PDFAbstract
Rich samples of benthic Peracarida collected from abyssal plains of the Angola Basin (South Atlantic) contained several new and rare asellote isopods. In this contribution, Eurycope tumidicarpus n. sp. is described from well-preserved specimens. This species is remarkable because the second pereopod has an enlarged carpus, and pereopod 4 is shaped like the posterior swimming legs. New specimens of Acanthocope galathea Wolff, 1962 (Fig. 1a) are used for a redescription, hitherto unknown characters of the male are shown.Diagnosis of Eurycope tumidicarpus n. sp. (Fig. 1b–g): Species with the diagnostic characters of Eurycope Sars, 1864 (see Wilson & Hessler 1981, Wägele 1989, Wilson 1989). Rostrum present but short, rounded, with two setae; width of cephalothorax about 0.7 of maximal body width; pereonite 5 about as long as pereonite 6 and with roughly parallel lateral margins, with rounded posterior edges; pereonite 7 more than twice length of pereonite 6; pleotelson wider than long, about as long as pereonite 7, without lateral or terminal projections, tip bent downward. Broad antennular article 1 three times wider than second article, with medial lobe bearing apically 4 spines, second article as long as first article. Carpus of pereopod 2 widened, broadly oval. Ischium, carpus, and propodus of pereopod 4 somewhat expanded and furnished with swimming setae, merus with a single swimming seta. Male pleopod 1 medially with 5 hemiplumose setae on ventral surface, distal tip of inner apical lobes rounded. Pleopod 2 with 7 proximolateral hemiplumose setae, protopod apically with small distal projection (vermiform appendage) bearing 2 short, hemiplumose terminal setae. Uropodal protopod with rounded medial projection, exopod smaller than half length of endopod.Types and locality: Holotype male (Zoological Museum Berlin Nr. 27400), 3.59 mm, collected from station St.350 on cruise M48/1 with RV “Meteor” (16°13.3′S 05°26.8′E – 16°14.9′S 05°26.7′ E, depth 5389 m). Paratype male (Zoological Museum Berlin Nr. 27400), 3.9 mm, from St.348 (16°17.1′S 05°27.3′E – 16°19.3′S 05°27.2′E, 5389-5387 m).
Received: 12 November 2001 / Accepted: 12 March 2002
The adult ventral nerve cord as a phylogenetic character in brachyceran DipteraDownload PDFAbstract
Insect ganglia are often composed of fused segmental units or neuromeres. We estimated the evolution of the ventral nerve cord (VNC) in higher Diptera by comparing the patterns of neuromere fusion among 33 families of the Brachycera. Variation within families is uncommon, and VNC architecture does not appear to be influenced by body shape. The outgroup pattern, seen in lower Diptera, is fusion of neuromeres belonging to thoracic segments 1 and 2 (T1 and T2), and fusion of neuromeres derived from T3 and abdominal segment 1 (A1). In the abdomen, neuromeres A7–10 are fused into the terminal abdominal ganglion (TAG). Increased neuromere fusion is a feature of the Brachycera. No brachyceran shows less fusion than the outgroups. We established six pattern elements: (1) fusion of T1 and T2, (2) fusion of T3 and A1, (3) fusion of the T1/T2 and T3/A1 ganglia, (4) increase in the number of neuromeres comprising the TAG, (5) anteriorward fusion of abdominal neuromeres, and (6) the complete fusion of thoracic and abdominal neuromeres into a synganglion. States 1 and 2 are present in the outgroup lower Diptera, and state 3 in the Xylophagomorpha, Stratiomyomorpha, Tabanomorpha and Cyclorrhapha. State 4 is a feature of all Eremoneura. State 5 is present in Cyclorrhapha only, and state 6, fusion into a synganglion, has evolved at least 4 times in the Eremoneura. Synapomorphies are provided for the Cyclorrhapha and Muscoidea, and a grouping of three basal brachyceran infraorders Xylophagomorpha, Stratiomyomorpha and Tabanomorpha. The patterns of fusion suggest that VNC architecture has evolved irreversibly, in accordance with Dollo's law.
Received: 09 October 2001 / Accepted: 16 January 2002
Rove beetles of the subtribe Scopaeina Mulsant & Rey (Coleoptera: Staphylinidae) in the West Palaearctic: Phylogeny, biogeography and species catalogueDownload PDFAbstract
A cladistic analysis of the West Palaearctic Scopaeina Mulsant & Rey, 1878 (Coleoptera, Staphylinidae: Paederinae) is presented along with bionomic and biogeographic information. A total of 76 morphological characters were coded for the 88 currently known West Palaearctic species, except for S. bifossicapitata (Outerelo & Oromi, 1987). Results show that Scopaeina comprises two well-supported monophyletic groups in the West Palaearctic, Micranops Cameron, 1913 and Scopaeus Erichson, 1840, which are considered to represent distinct genera. Phylogenetic relationships to Orus Casey, 1884, distributed in North and South America, are briefly discussed. Whereas Micranops is only represented by M. pilicornis (Baudi, 1869) in the region under study, 87 species of Scopaeus are currently known from the West Palaearctic. Within Scopaeus, the cladistic analysis yielded many well-supported monophyletic species groups, most of which are restricted to the West Palaearctic. However, except for Hyperscopaeus Coiffait, 1984, they are not in agreement with the widely used subgeneric concept sensu Coiffait (1952–1984). The following polyphyletic subgenera are consequently synonymized: Alloscopaeus Coiffait, 1968, Anomoscopaeus Coiffait, 1968, Geoscopaeus Coiffait, 1960, and Hyposcopaeus Coiffait, 1960 synn. n. = Scopaeus Erichson, 1840. Nivorus Herman, 1965, and Microscopaeus Coiffait, 1981 synn. n. = Micranops Cameron, 1913. The monotypical genus Coecoscopaeus Coiffait, 1984, established for C. coecus (Peyerimhoff, 1906), is excluded from Scopaeina. Scopaeus mitratus perroti Ochs, 1953 is raised to species rank, and S. nigellus Wollaston, 1864, formerly a synonym of S. minimus Erichson, 1939, is revalidated. Finally, we present a catalogue of species and synonyms of West Palaearctic Scopaeina along with distributional data and five new synonymies of species group names: S. bordei Peyerimhoff, 1914 syn. n. = S. portai Luze, 1910; S. tassiliensis Jarrige, 1958, S. mauretanicus Coiffait, 1960 synn. n. = S. crassipes Wollaston, 1867; S. saoudiensis Coiffait, 1981 = S. sinaicus Coiffait, 1970; S. mateui Coiffait, 1953 syn. n. = S. didymus Erichson, 1840. A lectotype is designated for S. didymus Erichson, 1840.See also Electronic Supplement (Parts 13) at http://www.senckenberg.de/odes/02-02.htm
Received: 13 March 2002 / Accepted: 12 August 2002
Hyalella armata (Crustacea, Amphipoda, Hyalellidae) and the description of a related new species from Lake TiticacaDownload PDFAbstract
Hyalella armata (Faxon, 1876) was considered for a long time to be a monotypic species. The peculiar morphology, very distinct from other species in Lake Titicaca, was not analysed in detail after the original description. However, the present authors' study of an extensive collection from The Natural History Museum in London has revealed two morphologically distinct species. Descriptions of H. armata and the new species H. longispina are given.Diagnosis of Hyalella longispina n. sp. (Figs 1, 2): Body (Fig. 1) with a posterior dorsal transverse ridge on every segment. Coxae 1 to 4 acuminate. Coxa 4 excavated posteriorly, and with deep acumination at right angle to sagittal body plane. Lateral process of coxa 4 strongly elongate (Fig. 2), distance between left and right process apices longer than body length (that distance shorter than body length in H. armata). Eyes pigmented. Antenna 1 shorter than antenna 2. Antenna 2 less than half body length. Mandible incisor toothed. Maxilla 1 palp uniarticulate, longer than wide, reaching more than half the distance between base of palp and tip of setae on outer plate; inner plate slender, with two strong and pappose apical setae. Maxilla 2 inner plate with one strong pappose seta on inner margin. Gnathopod 1 propodus quadrangular (length less than twice maximum width), hatchet-shaped, inner face with more than ten pappose setae, distoposterior and distoanterior borders without setose scales. Gnathopod 2 propodus triangular, palm longer than posterior margin, slope oblique, anterior edge with a small process. Telson wider than long, apically rounded, with more than two short simple setae, arranged symmetrically on the apical margin. Lateroventral sternal gills present on segments 3 to 7.Types and locality: Holotype male, 10 mm; PERU, Lake Titicaca, Choccocoyo Bay, St. P 6, GIC 481, 11-23 m, leg. Crawford, 25.VI.1937. Paratypes (collecting data as holotype): allotype female, 9 mm; 106 males, 6-10mm; 93 females, 5-10 mm. All deposited at The Natural History Museum, London (holotype: 2002.311; allotype: 2002.312; other paratypes: 2002.313-322).
Received: 15 April 2002 / Accepted: 09 July 2002
Taxonomy and new bacterial symbioses of gutless marine Tubificidae (Annelida, Oligochaeta) from the Island of Elba (Italy)Download PDFAbstract
In shallow sublittoral sediments of the north-west coast of the Island of Elba, Italy, a new gutless marine oligochaete, Olavius ilvae n. sp., was found together with a congeneric but not closely related species, O. algarvensis Giere et al., 1998. In diagnostic features of the genital organs, the new species differs from other Olavius species in having bipartite atria and very long, often folded spermathecae, but lacking penial chaetae. The Elba form of O. algarvensis has some structural differences from the original type described from the Algarve coast (Portugal). The two species from Elba share characteristics not previously reported for gutless oligochaetes: the lumen of the body cavity is unusually constricted and often filled with chloragocytes, and the symbiotic bacteria are often enclosed in vacuoles of the epidermal cells. Regarding the bacterial ultrastructure, the species share three similar morphotypes as symbionts; additionally, in O. algarvensis a rare fourth type was found. The divergence of the symbioses in O. algarvensis, and the coincidence in structural and bacteria-symbiotic features between the two taxonomically different, but syntopic host species at Elba are discussed.
Received: 01 July 2001 / Accepted: 02 April 2002
Morphological phylogenetics of the sea spiders (Arthropoda: Pycnogonida)Download PDFAbstract
Pycnogonids or sea spiders are a group of marine arthropods whose relations to the chelicerates have been an issue of controversy. Higher-level phylogenetic relationships among the lineages of sea spiders are investigated using 36 morphological characters from 37 species from all extant families and a Devonian pycnogonid fossil. This is one of the first attempts to analyze the higher-level relationships of the Pycnogonida using cladistic techniques. Character homoplasy (implied weights) is taken into account to construct a polytomous, most-parsimonious tree in which two major clades within Pycnogonida are obtained. Clade A includes Ammotheidae paraphyletic with Colossendeidae, Austrodecidae and Rhynchothoracidae, and clade B is formed by Nymphonidae, Callipallenidae (apparently paraphyletic), Pycnogonidae and Phoxichilidiidae. The analysis of equally weighted data is presented and helps to identify those characters less consistent. The reduction of the chelifores, palps and ovigers — shown independently within each of the clades as parallel evolution events — challenges the assumption of a gradual mode of reduction within the group, according to analysis of unordered vs ordered characters. Most of the phylogenetic affinities proposed here are compatible with traditional classifications. However, traditional taxonomic characters need to be complemented by sets of anatomical, molecular and developmental data, among others, to produce more robust phylogenetic hypotheses on the higher- and lower-level relationships of the sea spiders.
Received: 09 May 2001 / Accepted: 28 January 2002
Excavating and endolithic sponge species (Porifera) from the Mediterranean: species descriptions and identification keyDownload PDFAbstract
The present study is a review of the excavating and endolithic sponges present in the Mediterranean. A dichotomic key to 22 species is presented. Detailed species descriptions are provided based on newly collected material and previous descriptions from the literature. In the case of Cliona viridis (Schmidt, 1862), an in-depth histological study has also been performed. Discussions on problematic taxonomic issues are also included. Dotona pulchella Carter, 1880 subspecies mediterranea subsp. n. is described. The previously enacted synonymy between Pione vastifica Hancock, 1849 and Pione lampa (de Laubenfels, 1950) is restricted to those specimens identified as “forma occulta”. Cliona amplicavata Rützler, 1974 is recorded for the first time in the Mediterranean. Cliona cretensis Pulitzer-Finali, 1983 is proposed to be synonymous to Cliona thoosina Topsent, 1887. Cliona copiosa Sarà, 1959 and Cliona tremitensis Sarà, 1961 are considered synonymous to C. viridis.The spicule complement of Scantilletta levispira (Topsent, 1898), D. pulchellaand C. amplicavata is enlarged, and some spicule types are better described based on light microscopy and SEM observation. Pione vastifica shows great variability in the microrhabds, seemingly related to depth.Regarding excavating patterns, several species appear to selectively excavate particular substrate types, whereas others are not selective among calcareous materials.A. labyrinthica, P. vastifica, Cliona janitrix Topsent, 1932, C. viridis and C. lobata Hancock, 1849 have asexual reproduction. Excavating ability, bud production and the way the sponge grows inside the substrate are biological features common to distant taxa such as Clionidae and Aka spp. that may constitute convergent (analogous) characters.Access to colour pictures of some of the species described at http://atlantis.ceab.csic.es/~dani/clionids.html.
Received: 04 September 2001 / Accepted: 04 September 2002
Testing and weighting charactersDownload PDFAbstract
Published justifications for weighting characters in parsimony analyses vary tremendously. Some authors argue for weighting a posteriori, some for a priori, and especially those authors that rely on a falsificationist approach to systematics argue for non-weighting. To find a decision, while following the falsificationist approach, one first has to investigate the necessary conditions for the possibility of phylogenetic research to establish an empirical science sensu Popper. A concept of phylogenetic homology together with the criterion of identity is proposed, which refers to the genealogical relations between individual organisms. From this concept a differentiation of the terms character and character state is proposed, defining each character as a single epistemological argument for the reconstruction of a unique transformation event. Synapomorphy is distinguished from homology by referring to the relationship between species instead of individual organisms, thus the set of all synapomorphies constitutes a subset of the set of all homologies. By examining the structure of characteristics during character analysis and hypothesizing specific types of transformations responsible for having caused them, a specific degree of severity is assigned to each identity test. It thus provides a specific degree of corroboration for every hypothesis that successfully passed this test. Since the congruence criterion tests hypotheses of synapomorphy against each other on grounds of their degree of corroboration gained from the identity test, these different degrees of corroboration determine the specific weights given to characters and character state transformations before the cladistic analysis. This provides a reasonable justification for an a priori weighting scheme within a falsificationist approach to phylogeny. It also demonstrates the indispensable necessity of its application.
Received: 03 March 2002 / Accepted: 05 August 2002
The Tetraconata concept: hexapod-crustacean relationships and the phylogeny of CrustaceaDownload PDFAbstract
A growing body of evidence indicates that Crustacea and Hexapoda are sister groups, rather than Hexapoda and Myriapoda. Some recent molecular data even suggest that Mandibulata is not monophyletic, with Myriapoda and Chelicerata instead being sister groups. Here, arguments for homology of the mandible throughout mandibulate arthropods and for a monophyletic Mandibulata will be presented, as well as arguments supporting the taxon Tetraconata (i.e. Crustacea + Hexapoda). The latter include molecular data (nuclear and mitochondrial ribosomal RNAs and protein coding genes), and morphological characters such as ommatidial structure, the presence of neuroblasts and a very similar axonogenesis of pioneer neurons. However, crustaceans are insufficiently sampled for the molecular data, and studies of neurogenesis are lacking for many crustacean taxa. Remipedia, Cephalocarida and Maxillopoda are particularly problematic. This is important for the entire problem, because monophyly of the Crustacea has not yet been proven beyond doubt and several molecular analyses suggest a paraphyletic Crustacea. Here, arguments for the monophyly of the Crustacea are reviewed and two alternatives for the relationships between the five higher taxa Remipedia, Cephalocarida, Maxillopoda, Branchiopoda and Malacostraca are discussed: the Entomostraca concept sensu Walossek with Malacostraca as sister group to Cephalocarida, Maxillopoda and Branchiopoda, and the Thoracopoda concept sensu Hessler with Cephalocarida, Branchiopoda and Malacostraca forming a monophylum.
Received: 14 February 2002 / Accepted: 15 April 2002
Phylogenetic relationships of Cyrillaceae and Clethraceae (Ericales) with special emphasis on the genus Purdiaea PlanchDownload PDFAbstract
The phylogenetic relationships and systematic position of the three genera of Cyrillaceae (Ericales), Cyrilla, Cliftonia, and Purdiaea, were investigated by jackknife analysis of a combination of DNA sequences from the plastid genes atpB, ndhF, and rbcL. The results show that Cyrilla and Cliftonia together are the sister group of Ericaceae, whereas Purdiaea groups with Clethra of Clethraceae. Together, Clethra and Purdiaea form the sister group of (Cyrilla+Cliftonia)+Ericaceae. It is concluded that Purdiaea should be moved to Clethraceae. A cladistic analysis based on morphological data was performed to investigate relationships among the species of Purdiaea. The results indicate that Purdiaea belizensis from Central America is sister to all other species of the genus, and that Purdiaea nutans from northern South America is sister to the remaining group of species which are all Cuban endemics, among which P. cubensis from Pinar del Rio in western Cuba is sister to the eight species occurring in the Oriente province in eastern Cuba.
Received: 03 June 2002 / Accepted: 24 September 2002
Revision of the genus Noculacia Mayer, 1903 (Crustacea: Amphipoda: Caprellidea) with the description of two new speciesDownload PDFAbstract
The genus Noculacia Mayer, 1903 is reviewed. Two new species, N. africana n. sp. and N. australiensis n. sp., are described based on material collected from southeast Africa and western-southern Australia, respectively. Noculacia bullata Mayer, 1903, the type species of the genus, is redescribed. Noculacia bogisa Mayer, 1903 is transferred to the genus Pseudoprotella Mayer, 1890 mainly on the basis of the presence of a well developed molar, the structure of pereopods 3 and 4, and the setal formula of the mandibular palp being 2-x-1. The genus Noculacia is presently composed of three species: N. africana n. sp., N. australiensis n. sp, and N. bullata Mayer, 1903. The genus Pseudoprotella is composed of P. bogisa (Mayer, 1903), P. inermis Chevreux, 1927, and P. phasma (Montagu, 1804).
Received: 30 March 2002 / Accepted: 15 May 2002
The phylogeny of the genus Ischioscia Verhoeff, 1928, with redescriptions of three species (Crustacea: Isopoda: Oniscidea)Download PDFAbstract
The genus Ischioscia Verhoeff, 1928 is reviewed. 26 species are considered valid. A key for their identification is given, as well as a map showing the geographic distribution. The known range of the genus covers a large area from the central Amazon region to the mountains of Guatemala. The species of Ischioscia have a typical “philosciid” habitus (“runner” type); they can be distinguished from other Neotropical species with similar habitus by the following apomorphies: (1) male pereiopod 1 carpus enlarged to a plate-like extension, (2) scale field on male pereiopod 1 covering entire frontal side of the carpus, (3) male pereiopod 7 ischium with a ventral scale field, (4) dactylus in both sexes with a long inner claw. The groundpattern of Ischioscia is reconstructed, and an analysis of the phylogenetic relations within the genus is made on the basis of morphological data. The species are very similar to each other, most differences are found in the male structures of sexually dimorphic features. Ischioscia sturmi (Vandel, 1972), I. amazonica Lemos de Castro, 1955 and I. bolivari Vandel, 1968 are redescribed in detail.
Received: 07 March 2002 / Accepted: 14 June 2002
On the ground pattern of AnnelidaDownload PDFAbstract
Annelida, traditionally divided into Polychaeta and Clitellata, are characterized by serial division of their body into numerous similar structures, the segments. In addition, there is a non-segmental part at the front end, the prostomium, and one at the back, the pygidium. New segments develop in a prepygidial proliferation zone. Each segment contains four groups of chaetae made up of β-chitin, a pair of coelomic cavities separated by mesenteries, and septa. The nervous system is a rope-ladder-like ventral nerve cord with a dorsal brain in the prostomium. For the last stem species a trochophore larva and a benthic adult are commonly postulated. There are two conflicting hypotheses describing the systematization of Annelida: the first postulates a sister-group relationship of Polychaeta and Clitellata, the second sees Clitellata as a highly derived taxon forming a subordinate taxon within the polychaetes which, consequently, are regarded as paraphyletic. Depending on the hypothesis, different characters have to be postulated for the stem species of Annelida. Besides segmentation other characters such as nuchal organs, palps and antennae, body wall musculature, cuticle, parapodia as well as structure of the central nervous system and the foregut play an important role in this discussion. Here, the different characters and character states are critically reviewed and analyzed with respect to morphology and function. The consequences for systematization of their phylogenetic interpretation as autapomorphies, synapomorphies or plesiomorphies are outlined. The resulting hypotheses are compared with those relying on molecular data sets.
Received: 11 February 2002 / Accepted: 27 August 2002
Revision of the enigmatic Upper Carboniferous insect Campyloptera eatoni Brongniart, 1893 (Insecta: Odonatoptera)Download PDFAbstract
Campyloptera eatoni Brongniart, 1893, the type species of the type genus of the Upper Carboniferous family Campylopteridae Handlirsch, is redescribed. It is not a Megasecoptera as previously supposed, but an Odonatoptera with a specialized wing venation. Although it has a more basal position than the Meganeuridae because of the absence of any nodal or subnodal structure, it has acquired a simple vein MA and a widening area between MP and CuA, convergently with the highly derived Discoidalia clade that includes the modern Odonata. A new diagnosis is given for Campylopteridae and its type genus, Campyloptera Brongniart. Campylopterodea Rohdendorf, 1962 falls as a new junior synonym under Odonatoptera Martynov, 1932.
Received: 04 September 2001 / Accepted: 04 September 2002
Weighting indels as phylogenetic markers of 18S rDNA sequences in Diptera and StrepsipteraDownload PDFAbstract
Opinions split when it comes to the significance and thus the weighting of indel characters as phylogenetic markers. This paper attempts to test the phylogenetic information content of indels and nucleotide substitutions by proposing an a priori weighting system of non-protein-coding genes. Theoretically, the system rests on a weighting scheme which is based on a falsificationist approach to cladistic inference. It provides insertions, deletions and nucleotide substitutions weights according to their specific number of identical classes of potential falsifiers, resulting in the following system: nucleotide substitutions weight = 3, deletions of n nucleotides weight = (2n–1), and insertions of n nucleotides weight = (5n–1). This weighting system and the utility of indels as phylogenetic markers are tested against a suitable data set of 18S rDNA sequences of Diptera and Strepsiptera taxa together with other Metazoa species. The indels support the same clades as the nucleotide substitution data, and the application of the weighting system increases the corresponding consistency indices of the differentially weighted character types. As a consequence, applying the weighting system seems to be reasonable, and indels appear to be good phylogenetic markers.
Received: 20 July 2001 / Accepted: 23 November 2001
Analysis of phylogenetic relationships among Ascomycota with yeast phases using ribosomal DNA sequences and cell wall sugarsDownload PDFAbstract
Analysis of the monosaccharide composition of purified cell walls of unicellular and filamentous ascomycetous fungi shows three patterns: (1) the mannose glucose type (for most hemiascomycetous yeasts) (2) the mannose glucose galactose type (for several members of all three main ascomycetous clades) and (3) the mannose glucose galactose rhamnose type (for members of the Euascomycetes and the Protomyces/ Schizosaccharomyces group).In order to estimate the usefulness of the carbohydrate patterns for phylogenetic analysis we compared them with a phylogenetic tree based on 18SrRNA-gene sequences using the Neighbor-Joining Method. In contrast with the situation for basidiomycetous fungi, the Ascomycota show no fixed cell wall type for the three classes. Based on cell wall carbohydrates, sequence data and molecular characters the Hemiascomycetes appear as the first branch within the Ascomycota. A second clade, comprising the genera Schizosaccharomyces, Pneumocystis, Taphrina, Protomyces, Neolecta and Saitoella, appears as a sister group of the Euascomycetes. We discuss the erection of a new class for this group of ascomycetous fungi for which we propose the name Protomycetes.
Received: 22 February 2002 / Accepted: 06 June 2002
QTL analysis reveals different and independent modes of inheritance for diagnostic achene characters in Microseris (Asteraceae)Download PDFAbstract
There are few reliable diagnostic morphological characters for species of the asteracean genus Microseris, and quantitative differences in the shapes of the achenes and the paleaceous pappus parts play a decisive role in species recognition. The genetic basis of species and strain differences in various characters has been studied previously, but little is known about quantitative characters of the achenes.We performed a quantitative trait locus (QTL) analysis in the F2 of an interspecific cross between Microseris douglasii and M. bigelovii for achene length, achene diameter, achene shape, palea length, awn length, and achene pigmentation.Independent inheritance of the main heritable achene characters – achene length, palea length and achene pigmentation – was revealed by the detection of distinct and specific QTLs for these characters. For palea length five QTLs with about equal phenotypic effects were mapped on four different linkage groups. Achene length and achene shape (achene length / achene diameter) were determined by two different genetic systems with one major gene and two modifiers. The detection of QTLs with a polarity of the effects opposite to that in the parental strains for achene length and achene shape reveals genetic variation for a potential increase in species differences. For the highly heritable trait, achene pigmentation, the bimodal F2 distribution suggested single-factor inheritance for absence versus presence of spots, with dominance for the spotted condition. However, only relatively weak QTL effects on that trait could be detected. Additional molecular markers (RAPDs, AFLPs) have to be tested for cosegregation with that major gene. The results are discussed in the context of different theories for the evolution of morphological characters.
Received: 22 April 2002 / Accepted: 29 July 2002
Cynanchum and the Cynanchinae (Apocynaceae – Asclepiadoideae): a molecular, anatomical and latex triterpenoid studyDownload PDFAbstract
The phylogeny of the genus Cynanchum s. str. is studied using cpDNA spacers and ITS. Morphological, anatomical and latex triterpenoid data are interpreted in light of the molecular results, and discrepancies are discussed. Vegetative characters are better indicators of relationship than floral characters, especially corona characters. The monophyly of all Malagasy species and, nested within the latter, of all stem-succulent taxa is ascertained and the genera Folotsia, Karimbolea, Platykeleba and Sarcostemma are subsumed under Cynanchum. One African species, C. galgalense, is excluded from Cynanchum.
Received: 03 March 2002 / Accepted: 02 August 2002
The Articulata hypothesis – or what is a segment?Download PDFAbstract
The long held view that annelids and arthropods are closely related (Articulata) has been challenged recently by phylogenetic analyses using molecular data. The outcome of these studies is a clade of moulting animals (Ecdysozoa) comprising arthropods and some taxa of the nemathelminth worms. Monophyly of the Ecdysozoa has not yet been shown convincingly on morphological evidence, but is strongly supported by molecular data. The implication of the Ecdysozoa hypothesis is that the type of segmentation found in annelids and arthropods must be either convergent or an ancestral feature of protostomes or even bilaterians. The present review discusses aspects of segmentation in annelids and arthropods at the genetic, cellular, morphogenetic and morphological levels. Based on numerous similarities not shared with other bilaterian taxa it is suggested that segmentation of annelids and arthropods is homologous and apomorphic for a monophyletic Articulata. However, the challenge provided by the molecular analyses should stimulate research programmes gaining more data such as on additional genes, cleavage patterns, molecular developmental biology, and the comparison of nervous systems at the level of single neurons.
Received: 05 October 2001 / Accepted: 12 March 2002
Molecular phylogeny of Malagasy poison frogs, genus Mantella (Anura: Mantellidae): homoplastic evolution of colour pattern in aposematic amphibiansDownload PDFAbstract
We studied the evolution of colour pattern in Malagasy poison frogs, genus Mantella, a group of diurnal and toxic frogs endemic to Madagascar. Based on a phylogeny reconstructed using 1130 bp of the mitochondrial 16S rRNA gene, the genus can be divided into five species groups. Within some of these groups, interspecific genetic divergences were very low (1.2–2.8% sequence divergence) while colour patterns were markedly different. In contrast, Mantella madagascariensis and M. baroni, two species which show extremely similar dorsal coloration patterns, were not included in the same clade. This conclusion was supported by high bootstrap values and by significant rejection of alternative topologies using KH-tests. Analysis of colour patterns and tentative reconstruction of ancestral states yielded five character states shared by these two species but not by their respective sister species, M. aurantiaca and M. nigricans. Considering these detailed similarities as symplesiomorphic therefore requires the assumption of multiple reversals in other species, whereas a homoplastic colour evolution in the sympatric M. madagascariensis andM. baroni appears as most parsimonious. This parallelism may have been triggered by MÜllerian mimicry. However, additional data is necessary to support this hypothesis.