Received: 06 June 2000 / Accepted: 04 January 2001
Interpreting segment homologies of the maxilliped of cyclopoid copepods by comparing stage-specific changes during developmentDownload PDFAbstract
Development of the maxilliped of 14 species of cyclopoid copepods from 14 genera in the families Cyclopinidae, Oithonidae and Cyclopidae is described. Segment homologies are inferred from the assumption that homologous setae and arthrodial membranes are added during the same copepodid stage, and from a model of development that patterns the endopod proximally from the proximal of two endopodal segments present at the first copepodid stage. An arthrodial membrane separates the praecoxa and coxa of two Cyclopinidae and two of three Oithonidae. The praecoxa of the Cyclopinidae and the Oithonidae has two groups of setae; the praecoxa of Cyclopidae has no more than one group. The coxa of these copepods has only one group of setae; all Cyclopidae share a coxal lobe with a single seta. The endopod of these three families may include as many as five segments. In general, the distal arthrodial membrane of a segment appears to have been more labile during evolutionary history of the maxilliped than has the ventral seta which inserts on that segment. For purposes of phylogenetic analyses, uncoupling the presence of the distal arthrodial membrane of a segment from the presence of its ventral seta and analyzing each separately may provide a better way of understanding evolutionary transformations of the limb than considering the segment as the basic structural unit of the limb.
Received: 21 August 2000 / Accepted: 29 December 2000
The phylogeny of Gentianella (Gentianaceae) and its colonization of the southern hemisphere as revealed by nuclear and chloroplast DNA sequence variationDownload PDFAbstract
The generic circumscription and infrageneric phylogeny of Gentianella was analysed based on matK and ITS sequence variation. Our results suggested that Gentianella is polyphyletic and should be limited to species with only one nectary per petal lobe. Gentianella in such a circumscription is most closely related to one part of a highly polyphyletic Swertia. within uninectariate Gentianella two major groups could be recognized: 1) northern hemispheric species with vascularized fimbriae at the base of the corolla lobes, and 2) northern hemispheric, South American, and Austrlia/New Zealand species without vascularized fimbriae. When fimbriae are present in this latter group, they are non-vascularized. whereas ITS data suggested a sister group relationship between the fimbriate and efimbriate group, the matK data suggested paraphyly of the efimbriate group with Eurasian efimbriate species as sister to the remainder of the clade. Based on the phylogeny and using geological and fossil evidence and a molecular clock approach, it is postulated that the efimbriate lineage originated in East Asia near the end of the Tertiary. From East Asia it spread via North america to south America, and from there it reached Australia/New Zealand only once by a single long-distance dispersal event. The place of origin of the fimbriate lineage remained doubtful. The high specific diversity of Gentianella in South America probably resulted mainly from the availability of a very large alpine area open to colonization rather than from particularly high speciation rates in comparison to other taxa.
Received: 06 February 2001 / Accepted: 10 May 2001
Observations on the histology and photosynthetic performance of “solar-powered” opisthobranchs (Mollusca, Gastropoda, Opisthobranchia) containing symbiotic chloroplasts or zooxanthellaeDownload PDFAbstract
Literature data on diversity of photosynthetic activity in Opisthobranchia are reviewed and new histological data presented on the presence of zooxanthellae in members of the nudibranch clade Cladobranchia. Zooxanthellae are recorded here for the first time in members of the family Arminidae (Dermatobranchus) and in the aeolid Piseinotecus gabinierei. Although a broad histological survey on Nudibranchia has been performed, only species of the taxon Cladobranchia are reported to house zooxanthellae. A new method to measure photosynthesis is applied to opisthobranchs with chloroplasts and zooxanthellae. With a Pulse Amplitude Modulated Fluorometer (PAM), the chlorophyll a fluorescence and corresponding fluorescence yield (electron transfer) of photosynthetically active chloroplasts or zooxanthellae can be analyzed in vivo. This facilitates better understanding of the diversity of zooxanthella and chloroplast uptake (ranging from feeding up to highly evolved forms of symbiosis) in the different opisthobranch clades.
Received: 05 August 2000 / Accepted: 08 February 2001
Preliminary phylogenetic analysis of selected subterranean amphipod crustaceans, using small subunit rDNA gene sequencesDownload PDFAbstract
The exclusively subterranean amphipod genus Bactrurus (Crangonyctidae) occurs in central and eastern parts of the United States. Bactrurus is characterized by morphologically similar species. In at least one instance, the distinction between separate species and geographic variants appears to be blurred. A sequence analysis of the small subunit (18S) rDNA gene was conducted for eight amphipod taxa. Both maximum likelihood and distance methods resulted in phylogenies for several species of Bactrurus that are in accordance with morphological data. These results could not be validated by a parsimony analysis. All three methods of phylogenetic inference, however, produced identical basal branching patterns. The molecular analyses do not support the recognition of what initially appeared to be a new species of Bactrurus from glaciated areas in Montgomery County, Illinois.
Received: 06 July 2001 / Accepted: 16 October 2001
Antarctic caprellids (Crustacea: Amphipoda) collected during the “Polarstern” cruise 42 ANT XIV/2Download PDFAbstract
The recent “Polarstern” surveys, carried out within the framework of the international EASIZ (Ecology of the Antarctic Shelf Ice Zone) programme, have been representing a significant effort to improve the understanding of certain as yet poorly known animal groups in the southern ocean.A collection of caprellids from the “Polarstern” cruise 42 ANT XIV/2 contained five species in four genera: Caprellinoides mayeri (Pfeffer, 1888); C. tristanensis Stebbing 1888; Aeginoides gaussi Schellenberg, 1926; Pseudododecas bowmani McCain & Gray, 1971; and Paraproto condylata (Haswell, 1885). Although all were previously recorded from the Antarctic region, Pseudododecas bowmani and Paraproto condylata, poorly known from previous studies, are redescribed and illustrated in detail. The examined specimens of P. bowmani are in good agreement with the descriptions of McCain & Gray (1971) and Laubitz (1991), except for the outer lobe of maxilla 1, which has 5 robust setae instead of 6. McCain & Gray reported a setal formula 1-25-1 for the terminal article of the mandibular palp. However, Laubitzs specimen had a setal formula 1-11-1 as do the specimens of the present study. The pereopod 3 is only 4-articulate in the specimens examined. The fifth article is not indicated by an incomplete suture as reported by Laubitz (1991). These and other minor differences are probably due to differences of developmental stage or intraspecific variation. The illustrations of Paraproto condylata in Mayer (1903) and McCain & Gray (1971) were incomplete; detailed description and drawings of mouthparts, gnathopods, pereopods, and abdomen were lacking.
Received: 23 March 2001 / Accepted: 20 September 2001
The phylogeny of Nudibranchia (Opisthobranchia, Gastropoda, Mollusca) reconstructed by three molecular markersDownload PDFAbstract
The phylogeny of the Nudibranchia and its major constituent taxa is investigated by comparing the complete sequences of the 18S rDNA of 54 species, a part of the 16S rDNA of 38 species and part of cytochrome c oxidase I (cox1) of 45 species. These datasets are analyzed individually and in combination for the subset of taxa where information on all three markers is available. The results are compared to published cladistic analyses based on morphological data. The monophyly of the Nudibranchia and the monophyly of its two major groups, the Anthobranchia/Doridoidea and Cladobranchia, is confirmed. Incongruencies between the molecular and morphological data is discussed, as well as incongruencies between the three molecular markers.
Received: 09 October 2000 / Accepted: 29 December 2000
Utility of nuclear SSU and LSU rDNA data sets to discover the ordinal placement of the Coccotremataceae (Ascomycota)Download PDFAbstract
Informal ascomycete classifications have traditionally been based in part on ascomatal morphologies. The problems associated with grouping taxa using ascomatal characters are evidenced in the Coccotremataceae where the ascomata have been interpreted either as apothecia or perithecia. We used SSU rDNA sequences representing all classes of the Pezizomycotina to infer the phylogenetic position of the family. The Coccotremataceae clustered within the Lecanoromycetes. Since the Lecanoromycetes are characterized by the presence of apothecia, these data support the apothecial interpretation, given that the ascomata of the Coccotremataceae are not the result of convergent evolution. To evaluate the ordinal placement of the Coccotremataceae we used sequences of the SSU rRNA and LSU rRNA gene of 12 Lecanoromycetes. The SSU and LSU portions of this second analysis reveal conflicting phylogenies. Therefore we compared the two portions with additional statistical tests: splits decomposition, an analysis of the distribution of homoplasy, and a calculation of the ideal nucleotide substitution rate. In all of these tests the LSU data performed better than the SSU data. The results of the incongruence length difference (ILD) test suggest the data portions could be combined. There is no difference in the tree topology of the combined data set and of the LSU portion only, but the bootstrap values in the combined tree are lower. We argue that the low bootstrap supports in the combined tree are due to the phylogenetic signal in the SSU data set. Therefore we use the LSU and the combined tree to base our classification of the Coccotremataceae. In the LSU and the combined tree the inclusion of the Coccotremataceae in the Pertusariales is supported as is the sister relationship of the Pertusariales and Agyriales. Within the Pertusariales the Coccotremataceae and Pertusariaceae are well-supported sister taxa.
Received: 15 November 2000 / Accepted: 22 January 2001
Supralitoral talitrid Amphipoda and oniscid Isopoda (Crustacea) from the Southwest African coastDownload PDFAbstract
The amphipod crustacean species Talorchestia skoogi, Talorchestia quadrispinosa, Talorchestia tricornuta, collected on the southwest coast of Africa, and the isopod Deto echinata from the same geographic region are redescribed (10 pp.) and illustrated in detail (22 plates with b/w drawings). Records of other amphipod and isopod species occuring at the same localities are given.
Received: 05 August 2000 / Accepted: 23 October 2000
Phylogenetic relationships of the Australasian Coelometopini (Coleoptera: Tenebrionidae); a quantitative cladistic analysis with a review of biologyDownload PDFAbstract
The phylogeny of a number of diverse, tropical Australian lineages has been studied recently to lay the groundwork for biogeographic analyses. As part of this effort, we present here a cladistic analysis of the Australasian Coelometopini (Coleoptera: Tenebrionidae: Coelometopinae). A total of 101 morphological characters were coded for 50 taxa. Results show that the Australasian Coelometopini comprises several well-supported clades and that the majority of flightless species from Australian high elevation rainforests form a single monophyletic group. Features of the female genital tube and ovipositor were especially useful in determining close relationship within the tribe. The Coelometopini has been redefined over recent years, and we synthesize and summarize the biology and ecology of the group taking into account the most current circumscription.
Received: 21 August 2000 / Accepted: 25 October 2000
Anatomy and histology of Corambe lucea Marcus, 1959 (Gastropoda, Nudibranchia, Doridoidea), with a discussion of the systematic position of CorambidaeDownload PDFAbstract
The phylogenetic position of Corambidae has been subject to much speculation. Most of the confusion has arisen from insufficient anatomical knowledge and from interpretations which have not followed the rules of Hennigian phylogenetic systematics. In this study, as a model system, the poorly known Chilean species Corambe lucea Marcus, 1959 is redescribed in detail: digestive, reproductive, central nervous, circulatory, and excretory systems are examined anatomically and histologically. New biological data are also given. After critical comparison with congeners, C. lucea is confirmed to be a valid species. Major organ systems of C. lucea are discussed comparatively and used to resolve phylogenetic relationships. Gill structure and circulatory system of the Corambidae are homologous to that of the Anthobranchia bauplan but not to the secondary gills and circulatory system of the Phyllidiidae. The similar lateral position of respiratory organs and a posteroventral anus in some Corambidae and Phyllidiidae is clearly due to convergence; the two groups are true doridoidean nudibranchs but there is no indication for a sistergroup relationship. Corambids are shown to belong to the monophyletic group Suctoria which is characterized by the unique and complex autapomorphies “possession of a dorsal buccal pump” and “possession of a large first lateral tooth with a long, denticulated hook”.
Received: 22 November 2000 / Accepted: 23 May 2001
A new species of sea anemone from Chile, Anemonia alicemartinae n. sp. (Cnidaria: Anthozoa). An invader or an indicator for environmental change in shallow water?Download PDFAbstract
The new species, Anemonia alicemartinae (Actiniidae), is described from rocky shores of north and central Chile. Its members' abundance, occurrence in exposed positions, and bright red colour make it one of the most eye-catching species of northern Chile. The description is based on 74 specimens collected between 1975 and 2001, and on live observations of several hundred animals in their habitats and in aquaria. The natural microhabitats are positions exposed to currents but protected from surge surf, ranging from tide pools down to depths of 16 m. In 1998, the southern distribution limit was 37 °S, the southernmost extent of the southerly Chile Coastal Countercurrent. The species is similar to Anemonia natalensis and Pseudactinia varia from South Africa. The most distinctive features of A. alicemartinae n. sp. are its bipartite acrorhagi on the margin, uniform red colour, and marks from frequent longitudinal fission. Bud-like structures were observed in two specimens. Evidence of frequent fission and the absence of fertile males in the sample indicate a predominance of asexual reproduction in the population. The fact that such a conspicuous species was not reported in previous surveys of Chilean sea anemones suggests that it has been increasing in abundance and/or expanding its range during the last 50 years. Reasons for this may be human impact on benthic communities or recent introduction of this species into the area.
Problems and perspectives in the systematics of NematomorphaDownload PDF
Received: 10 July 2001 / Accepted: 05 October 2001
New records of little known deep-sea Echinothambematidae (Crustacea: Isopoda: Asellota) with redescription ofVemathambema elongata Menzies, 1962 and description of a new species from the Argentina BasinDownload PDFAbstract
The family Echinothambematidae and the genus Vemathambema Menzies, 1962 are rediagnosed. A redescription of Vemathambema elongata Menzies, 1962 from the Angola Basin and the description of Vemathambema argentinensis sp. nov. from the Argentina Basin of the South Atlantic are presented. The new species can easily be distinguished from Vemathambema elongata by its larger opercular pleopods and deeper constrictions of pereonites two to four.Family Echinothambematidae Menzies, 1956Vemathambema elongata Menzies, 1962 (Fig. 1a, b)New material examined: German expedition “DIVA 1” (RV “Meteor” cruise 48/1): 22.7.2000, St. 338, 18°19.4′S 04°39.7′E, depth 5397 m, 1 female, 3.5 mm long; St. 340, 18°18.3′S, 04°41.3′E, depth 5395 m 1 female, 3.2 mm long; 28.7.2000, St. 348, 16°18.1′S 05°27.2′E, depth 5390 m, 1 juvenile female, 1.8 mm long. Russian Expedition RV “Akademik Kurchatov” (cruise 43): 13.1.1986, St. 4912, 26°45.1′S, 06°54.6′E, depth 4910 m, posterior part of male.Vemathambema argentinensis sp. nov. (Fig. 1c, d)Material examined: Russian expedition RV “Akademik Kurchatov” (cruise 43): 26.12.1985, St. 4893, 36°12′S 49°09′W, depth 4630 m. Holotype: male, 4.6 mm long, (Zoological Museum of Moscow University, ZMMU Mc 1322a). Paratypes: female allotype with oostegites on first pereopods, 4.7 mm long; 1 female, 4.2 mm; 2 adult males, 4.7 and 4.3 mm; 2 immature males in stage IV, 3.2 and 3.1 mm (see Wolff 1962); pleotelson of a male (ZMMU Mc 1322b-c).Description: All segments free. Body length more than 5 times width of pleotelson, more than 10 times width of narrowest part of pereon, anterior parts of tergites 3 and 4 about twice as wide as narrowest middle parts. Male pereopod 1 carposubchelate, length 0.25 of body length, carpus larger than ischium, propodus as long and half as wide as carpus. Operculum of female broad oval, 1.4 times as long as wide, 0.83 of pleotelson length. Male pleopod 1 length 0.9 of pleotelson length, 3 times as long as narrowest width, 2.6 times proximal width, and 2.1 times broadest distal sagittal part width; distolateral lobes bent dorsally, reaching 0.15 of total pleopod length, ventral and lateral margins with sparse setules. Male pleopod 2 protopod 3 times as long as wide in ventral view, truncated apically, proximomedial lobe length 0.15 of protopod length and 0.75 of protopod width; endite proximal article subequal in width to distal article, stylet very thin, curved, longer than protopod; exopod situated distally, longer than wide, covered apically with hair-like setae. Uropods uniramous, 0.4 of body length, tapering distally.Diagnosis: The new species is very similar to V. elongata, but can easily be distinguished by the relatively large operculum in both sexes. In a male of V. argentinensis sp. nov. it occupies almost the whole ventral area of the pleotelson, in V. elongata it covers only nearly 70% of the ventral area. Male pleopods 1 of the new species are more slender, distolateral lobes are less curved dorsally. All parts of pleopod 2 are more slender. The new species is distinguished also by a thinner body, pereonites 14 with more pronounced anterolateral projections which in pereonite 2 have the same shape as in the two following pereonites, without tubercles. The central constriction on pereonites 3 and 4 is narrower in the new species. Pereopod 1 is stouter, but we could examine it only in a male whereas for V. elongata the pereopod 1 is known only for a female, the difference could be due to sexual dimorphism. The epipod of the maxilliped in V. argentinensis sp. nov. is longer than in V. elongata in relation to the basis. The two first articles of antenna 1 are somewhat stouter in the new species. In males with the same size of pleotelson the uropods are shorter in the new species (the uropod/pleotelson length ratio is 2.2 in V. argentinensis sp.nov. and 2.9 in V. elongata).
Published online: 01 May 2001
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Received: 05 February 2001 / Accepted: 10 April 2001
Systematics and character evolution in Durio s. lat. (Malvaceae/Helicteroideae/Durioneae or Bombacaceae-Durioneae)Download PDFAbstract
A molecular phylogenetic study of Durio s.lat. was conducted based on sequences of the internal transcribed spacer (ITS) of nuclear ribosomal DNA for 30 ingroup exemplars, representing 16 species, and two taxa of Cullenia as outgroups. The phylogeny suggests the existence of two well-circumscribed clades composed, respectively, of species with poricidal pollen locules (Boschia) and species with pollen locules that open with longitudinal slits (Durio s.str.). The latter clade is subdivided into two strongly supported clades: /Tubulidurio, with highly fused filaments and free calyx lobes, and /Palatadurio, with largely free filaments and connate calyx lobes. We provide phylogenetic definitions for the names of these well-supported clades. Reconstruction of floral evolution is consistent with the hypothesis that vertebrate pollination is ancestral for Durio s.lat. and Cullenia. However, there have been further shifts in pollination system within Durio s.lat., which may account for some of the current diversity of floral characters. The correlation of fruit and aril characteristics suggests that there are two major dispersal syndromes, involving either birds (fruits opening on trees; aril red/yellow and odorless) or terrestrial mammals (fruits opening only after falling to the ground; aril pale colored and pungent). The distribution of extant taxa implies a Malesian origin and radiation of the study group, with a single dispersal of Cullenia to India and Sri Lanka. However, the fossil pollen record raises the possibility that Durio and relatives may have migrated to Southeast Asia from the Indian subcontinent after it collided with Asia. A molecular clock analysis suggests that the earliest divergence within the study group occurred about 20 to 32 mya and, hence, does not favor either biogeographic scenario.
Received: 15 February 2001 / Accepted: 06 April 2001
Ultrastructure of Joenina pulchella Grassi, 1917 (Protista, Parabasalia), a reassessment of evolutionary trends in the parabasalids, and a new order Cristamonadida for devescovinid, calonymphid and lophomonad flagellatesDownload PDFAbstract
The parabasalids include parasites (e.g. trichomonads) as well as many hypermastigid flagellates which live in termites and other wood-eating insects and contribute to the cellulose-digesting capacity of those animals. A hypermastigid, Joenina pulchella Grassi, is shown to have a “flagellar area” composed of 1300 flagella, including three privileged basal bodies which have homologues in the trichomonads. The cytoskeleton includes preaxostylar fibres, two parabasal fibres and two atractophores with the parabasal fibres subdividing to form many parabasals. The microtubular rows of the pelta-axostyle system surround the flagellar area and converge towards a multispiralled axostylar trunk. On the basis of similarities of ultrastructure, joeniids and devescovinids are argued to be members of the same clade. Projoenia Lavette is in the sister group to Devescovina Foa and gives rise to the series Placojoenia Radek, Joenia Grassi, Joenina Grassi. Projoenia has a “flagellar area” as in the joeniids, but also a recurrent flagellum with a paraxonemal fibre and a cresta as does Devescovina. Projoenia has a parabasal fibre twisted around the axostyle, as well as a multispiralled axostyle. In Placojoenia, Joenia and Joenina the recurrent flagellum is absent or reduced to the basal body as is the cresta; the parabasal apparatus becomes multibranched. The classical Hypermastigida is in need of major revision. Parabasalids such as Lophomonadidae, Joeniidae, Deltotrichonymphidae, and possibly Rhizonymphidae and Kofoidiidae, collectively the lophomonads, have conserved the trichomonad/devescovinid organization and have a trichomonad-like morphogenesis involving only the privileged basal bodies and attached fibres. They can be distinguished from the rest of hypermastigids and should be classified with the Devescovinidae and Calonymphidae in a large clade — the Cristamonadida (new order). The remaining hypermastigids (the Trichonymphina and Spirotrichonymphina) have a rostrum which separates in two hemi-rostra at division, form a sister group to all other parabasalids and are not closely related to the remainder of the hypermastigids.
Received: 25 September 2000 / Accepted: 26 April 2001
Geographical diversity of genomic lineages in Bacillus subtilis (Ehrenberg) Cohn sensu latoDownload PDFAbstract
Prior genetic studies of wild isolates of Bacillus subtilis (Ehrenberg) Cohn from a single site in Arizona, USA, revealed four deeply separated lineages within this bacterial species traditionally defined through its physiological traits. The present study examines isolates from eight sites at varying degrees of geographical separation to assess the global genomic variation of B. subtilis. Sites are located in Arizona, California, and Utah in the USA, and in Mexico, Chile, Chad, Tunisia, and China. Using a random 10-bp PCR primer, RAPD DNA fingerprints were obtained for 106 isolates. From these data a UPGMA dendrogram was constructed. Six major genomic lineages separating at 9–18% similarity were found. Tree topology was virtually identical with an independently derived phylogeny using distinctly different data. Three lineages were the same as previously observed in Arizona, two were new, and one involved association of a small cluster of Tunisian isolates with the single member of a distinctive fourth lineage from Arizona, though this association was ambiguous. Four of the lineages were found on three or four continents; the others were found only on one or two continents depending on the interpretation of the ambiguous association. Within each major lineage there were cascades of sublineages. Some sublineages exhibited geographically local genomic differentiation; others mingled similar genomes from geographically distant locations. The major lineages separated at levels of genomic similarity only slightly different from those observed with random permutations of the data.
Received: 02 February 2001 / Accepted: 23 April 2001
Best systematist practice transferred to molecular dataDownload PDFAbstract
In the first part of the paper, we give a short description of the “minimum conflict” phylogeny estimation algorithm that analyzes molecular data in a way that resembles traditional best practice in morphological systematics. The algorithm calculates the tree from the root to the leaves, focussing on the detection of shared novel (synapomorphic) character states. Following the encaptic order of monophyla, at each step an outgroup serves to distinguish shared novel from shared old character states. The group of species under consideration is split in such a way that no synapomorphies of subgroups are torn apart, indicating that the split divides the group into two monophyla. In the second part of the paper, we describe the validation of our method with both natural and artificial data. Our method is very fast in theory, enabling the analysis of large quantities of data on a genomic scale. A Perl prototype is available on the World-Wide Web, via http://bibiserv.techfak.uni-bielefeld.de/mcope/.
Received: 04 July 2000 / Accepted: 25 November 2000
Paravireia holdichi n. sp., an enigmatic isopod crustacean from the Canary Islands with affinities to species from New ZealandDownload PDFAbstract
Paravireia holdichi n. sp. is reported from the Canary Islands, western Atlantic Ocean. The new species was discovered within empty barnacle shells in areas of intense tourism. It differs from other species of the genus in having a distinctive shield-like shape of the head and prominent lateral keels on anterior pereonites of males. The genus is unique within the Isopoda in lacking any trace of the uropoda. It is remarkable that the two other known species of the genus occur only in New Zealand. Three species are known, the type species Paravireia typica Chilton, 1925, from the supralittoral, and P. pistus Jansen, 1973, from the sublittoral, each from single localities in New Zealand, while Paravireia holdichi n. sp. is known from several supralittoral locations in the Canary Islands. Comparison with known isopod taxa leads to the conclusion that Paravireia does not fit clearly into any known isopod family, although on the basis of overall similarity of the antennule, antenna, mouthparts and pereopods the genus is regarded as incertae sedis with the strongest affinities to the Sphaeromatidae.
Received: 15 February 2000 / Accepted: 09 August 2000
Phylogeny and biogeography of South American Crinocheta, traditionally placed in the family “Philosciidae” (Crustacea: Isopoda: Oniscidea)Download PDFAbstract
South America is diverse in climatic and thus vegetational zonation, and even the uniform-looking tropical rain forests are a mosaic of different habitats depending on the soils, the regional climate and also the geological history. The terrestrial Isopoda (Oniscidea) constitute an important link in the nutrient webs of the rain forests. They participate in soil formation by shredding leaf litter when foraging on the associated fungi and bacteria.After a century of research on this interesting taxon, a revision of the terrestrial isopod taxa from South America and some of the Antillean Islands, which are traditionally placed in the family Philosciidae, was performed to establish monophyletic genera. In addition, the phylogenetic relationships of these genera are elucidated in the light of phylogenetic systematics. Several new taxa are recognized, among them the two genera Plataoniscus gen. n. and Pulmoniscus gen. n.; the former name replaces Plataoniscus Vandel (1963) which is not an available name according to § 13a ICZN because a type species was never designated.Diagnosis of Plataoniscus gen. n.: Cephalothorax with linea frontalis and faint linea supra-antennalis, lateral lobes present, compound eyes composed of more than 20 ommatidia. Antenna with three-articulate flagellum bearing short apical organ. Maxillula with 4 + 5 slender teeth on lateral endite, maxillula with lateral lobe two times broader than medial one, maxilliped without knob-like penicil on endite. Pereopods with simple dactylar setae. Pleopods with exopodites bearing more than 20 sensory spines laterally, in apical region a second row more centrally, covered lungs in all pleopods, lungs 1 to 2 monospiracular, lungs 3 to 5 multispiracular, spiracular area covered with pectinate scales and a derivative of those scales, forming a triangular lobe.The autapomorphies of Plataoniscus gen. n. are:
Pleopod 1 to 5 exopodites with covered lungs, monospiracular in pleopods 1 and 2, multispiracular in pleopods 3 to 5.
Perispiracular area with triangular or three-tipped cuticular scales as derivatives of pectinate scales.
Pleopod exopodites with second, more centrally located row of sensory spines in apical region.
Male pleopod 5 exopodite with furrow on medial margin of caudal surface.
Type species of the genus is Plataoniscus borelli (Dollfus, 1897).Diagnosis of Pulmoniscus gen. n.: Cephalothorax without lateral lobes and linea frontalis, linea supra-antennalis present, compound eyes consisting of 14 ommatidia in three rows. Antennula three-articulate with coniform distal joint, antennae with three-articulate flagellum bearing short apical organ. Maxillula with 4+5 teeth on lateral endite, inner set cleft, maxillipedal endite without knob-like penicil. Pereopods with simple dactylar setae, coxal plates with nodulus lateralis and sulcus marginalis. Pleopods with rhomboidal exopodites bearing covered lungs, perispiracular area concentrically wrinkled, endopodites subrectangular.The autapomorphies of Pulmoniscus gen. n. are:
Cephalothorax without lateral lobes.
Lateral endite of maxillula with particular teeth, bearing a crown-shaped, 3-tipped apex.
Covered lungs in all five pairs of pleopod exopodites.
Spiraculum opening distally at more than one third of lateral length.
The type species of this hitherto monotypic genus is Balloniscus insularuminfraventum Vandel, 1952.Two further new taxa are established on a higher taxonomic level: within the family “Philosciidae” two supergeneric taxa are recognised. Both are endemic in the Neotropics:The new tribe Ischiosciini trib. n. is defined by the following apomorphies:
Antennula with proximal article bearing a shield-like protrusion distally.
Pleotelson with ventral semicircular pit apically. The following genera are members of this tribe: Ecuadoroniscus Vandel, 1968, Oreades Vandel, 1968, Tropiscia Vandel, 1968, Mirtana Leistikow, 1997, and Ischioscia Verhoeff, 1928, the latter is the typical genus.
The new tribe Prosekiini trib. n. is established for the genera Prosekia Leistikow, 2000 (the type genus), Metaprosekia Leistikow, 2000, Xiphoniscus Vandel, 1968, Andenoniscus Verhoeff, 1941, Androdeloscia Leistikow, 1999, and Erophiloscia Vandel, 1972. It is characterised by the following autapomorphies:
Antennula with the medial aesthetascs gathered in a tuft, directed more or less medio-distally, not attached to article 3.
Transverse fold between aesthetasc tuft and distal pair of aesthetascs.
Male pleopod 1 with hyaline lamellae near apex.
There are several more undescribed taxonomic units which are partially neotropical, partially also found on other continents, particularly on the old Gondwanan fragments. These monophyla are not formally named because of the lack of sufficient data. They were checked for their distribution patterns which are compared with patterns of other taxa from South America. Some correspondence was found: typical patterns are northwestern Neotropics, southwestern new world Australis, and southeastern new world Australis. Particularly the southern taxa have relationships to paleotropical taxa. The distribution patterns are analysed with respect to the evolution of the Oniscidea and to the geological history of their habitats.Full article at: http://www.senckenberg.uni-frankfurt.de/odes/01-04.htm
Received: 27 October 2000 / Accepted: 04 February 2001
Low diversity of spongicolous Amphipoda (Crustacea) observed in the Antarctic autumnDownload PDFAbstract
Sponges represent a major component of the Antarctic zoobenthos. They are known to act as hosts for several invertebrates. In the present investigation a total of 1193 specimens of Amphipoda living in the sponge tissue of three species of Demospongiae were observed. The sponges were collected in the Weddell Sea and at the Antarctic Peninsula in April, during the Antarctic autumn 2000. The population density, species richness, composition, and reproductive biology of the spongicolous Amphipoda was studied. More than 40 individuals were collected per 1000 cm3 sponge tissue. Females of all species had eggs or embryos in their marsupia. Interestingly, their young will be released — even though most of the studied species are filter feeders — in the Antarctic autumn and winter. Spongicolous inquiline Amphipoda may therefore not be influenced by the seasons as much as their free living relatives.
Received: 16 March 2001 / Accepted: 02 July 2001
Oversized enchytraeids (Annelida, Clitellata): a comparative study, with a revised description of Lumbricillus maximus (Michaelsen)Download PDFAbstract
Syntypes of the circum-AntarcticLumbricillus maximusMichaelsen, 1888) are re-examined, and a giant Fridericiaworm referable to F. hegemon(Vejdovsky, 1878) sensu lato is described from Greece. Their anatomical features are compared to those of two other gigantic representatives of the Enchytraeidae: Mesenchytraeus antaeusRota & Brinkhurst, 2000 and Henlea yukonensisTynen & Coates, 1991, both Canadian. Besides disclosing the structural peculiarities of the four genera, the observed differences are shown to reflect specific adaptations to particular environments, as exemplified by certain traits of the chaetae and body wall. In all four species, the nephridial apparatus is well developed and distributed along the body. The scheme of the vascular system follows the basic pattern of the family, with neither blood supply to the nephridia nor intraepidermal capillary networks, in spite of the increased respiratory needs imposed by a larger body and greater muscular activity. This and other design constraints imply limitations with regard to the geographical and ecological distribution of giant species within this family.
Received: 14 August 2000 / Accepted: 26 November 2000
Evolution of growth form in epiphytic Dissochaeteae (Melastomataceae)Download PDFAbstract
We trace the evolution of root climbing and scrambling in Dissochaeteae and Sonerileae, two closely related groups that comprise the majority of Old World climbing Melastomataceae. The morphological and anatomical adaptations of the different climbers are interpreted in the context of a phylogeny based on chloroplast (cp) DNA sequences of the ndhF gene, generated for 31 representatives of Dissochaeteae and Sonerileae/Oxysporeae plus nine outgroups. For 20 of these taxa, the ndhF sequences were combined with cpDNA rpl16 intron sequences to obtain higher statistical support. Parsimony, minimum evolution, and maximum likelihood approaches yield congruent topologies that imply that scrambling growth evolved once in the common ancestor of Dissochaetinae, a group of ∼40 species centered around Dissochaeta and its close relatives Macrolenes and Diplectria. Root climbing, on the other hand, likely evolved in the common ancestor of Catanthera, Kendrickia, and Medinilla section Heteroblemma (together 26 species). In Melastomataceae overall, scrambling is restricted to Dissochaetinae, while root climbing has evolved several times. The scramblers are diverse in open disturbed habitats and show adaptations such as sarmentose branches, hook-shaped adventitious roots, and interpetiolar outgrowths that enhance their ability to lean on and clamber over other plants. Root climbers in the Catanthera-Kendrickia-Heteroblemma clade are restricted to humid habitats and show adaptations such as anomalous growth of the secondary xylem (a rare feature in the family), living climbing roots, and pseudoalternate phyllotaxy, which allows optimal arrangement of the normally opposite melastome leaves against the host's trunk.
Received: 11 October 2001 / Accepted: 18 October 2001
The influence of classification on the evolutionary interpretation of structure a re-evaluation of the evolution of the pallial cavity of gastropod molluscsDownload PDFAbstract
The gastropod mantle, or pallial, cavity and its associated structures have served as a phylobase for studies of gastropod relationships for well over 100 years. We review C. M. Yonge's model for the evolution of the gastropod pallial cavity published a little more than 50 years ago, as well as its subsequent mutation by other authors. We then use a recently published (Ponder & Lindberg 1997) phylogenetic hypothesis of gastropod relationships to explore character transformations of attributes associated with the pallial cavity.Significant features of the evolution of the gastropod pallial cavity are the reduction or loss of structures (gill, osphradium, hypobranchial gland) and associated neural and reno-vascular systems on the right side of the cavity, and mechanisms for coping with an increase in overall body size in many clades. The loss of pallial cavity structures has occurred independently in several major clades, the patellogastropods, neritopsines, cocculinoideans, and apogastropods, and probably more than once in the vetigastropods. Evolution of the pallial cavity and associated structures is discussed for each of the clades in which largely different solutions are found to enable the achievement of larger body size. A seeming contradiction reduction of gills with increasing respiratory demand due to increasing body size is a feature of the group. We also examine possible linkages between the evolution of the pallial cavity and other morphological characters that were not suspect as a prioricorrelates of one another.The uncritical application of a current taxonomy to results obtained from applying the comparative method used to study form and function has been a significant hindrance to our understanding of evolution in the last several decades. C. M. Yonge's scenario published in 1947 was close to our phylogenetically based hypothesis. However, when it was later forced into agreement with the dominant classification of the last half-century (Thiele 1929–35), most of the points of agreement between the original scenario of Yonge and our phylogenetic hypothesis vanished, with four separate derivations reduced to a single event. This is an example of a Procrustean evolutionary scenario fitting the data to a classification scheme, with taxonomy rather than phylogeny used as the bed.
Received: 08 May 2001 / Accepted: 24 October 2001
Euscorpius balearicus Caporiacco, 1950, stat. nov. (Scorpiones: Euscorpiidae): molecular (allozymes and mtDNA) and morphological evidence for an endemic Balearic Islands speciesDownload PDFAbstract
The geographic variation of the circum-Mediterranean scorpion species Euscorpius carpathicus (L.) was traditionally analysed using morphological characters such as trichobothrial patterns, which resulted in the recognition of 23 subspecies; however, the biological reality of these subspecies remains unclear. Here, we focus on populations from the western Mediterranean and provide new molecular evidence that those from the island of Mallorca (Balearic Islands, Spain) represent a highly divergent lineage separate from E. carpathicusfrom the mainland of France (Vaucluse) and Italy (Liguria and Piemonte). This divergence is evidenced by morphological analysis. Moreover, allozyme and mtDNA divergences (about 10%) agree with our hypothesis that the Balearic island populations became isolated from the mainland about 5 Ma BP since the refilling of the Mediterranean Basin and have to be considered autochthonous. This hypothesis is additionally supported by the comparison of the genetic differentiation between artificially transplanted island populations and mainland populations in the congeneric species E. flavicaudis(de Geer). The phylogenetic species concept (PSC) is applied to elevate the subspecies E. carpathicus balearicus Caporiacco, 1950 to species rank. A lectotype is designated for this species.
Published online: 01 January 2001
Editorial: First Issue of the Journal "Organisms, Diversity & Evolution"Download PDF