Bivalvia – a look at the Branches

Systematic research on bivalved molluscs (Mollusca: Bivalvia = Pelecypoda) is briefly reviewed in an introduction to a series of papers focusing on seven of the larger branches of the bivalve tree. These are presented in an attempt to summarize current knowledge, to stimulate new research and to highlight needs for future research focus. A revised classification of extant bivalve families (with synonyms and included subfamilies) is presented, based on information compiled from the latest palaeontological, morphological and molecular data.  © 2006 The Linnean Society of London, Zoological Journal of the Linnean Society , 2006, 148 , 223–235.     

The systematics and biology of the Costa Rican species of parasitic wasps in the Thyreodon genus-group (Hymenoptera: Ichneumonidae)

This paper presents an eco‐taxonomic study of the Neotropical representatives of the Thyreodon genus‐group (Hymenoptera: Ichneumonidae) present in Costa Rica, i.e. species of the genera Thyreodon and Rhynchophion. These ichneumonids are koinobiont endoparasitoids of the larvae of Sphingidae and Saturniidae. Intensive sampling in Costa Rica, conducted over 15 years, has revealed the presence of 23 species (12 of which are described here as new –Rhynchophion woodi, Thyreodon woodleyi, T. papei, T. whitfieldi, T. deansi, T. walkerae, T. sharkeyi, T. zitaniae, T. delvarei, T. schauffi, T. darlingi and T. carmeani), whereas earlier studies recognized only nine species in the same area. Several of the additional species we found are simply very scarce and thus unlikely to be encountered except by the type of intensive survey that, in the tropics, has only been conducted in Costa Rica. In some other cases, it has become apparent that more than one species has previously been confused under a single name. Thyreodon rufothorax Cameron is shown to be morphologically and biologically distinct from T. atriventris (Cresson), with which it has long been synonymized, and the relatively well‐known, chromatically distinctive species ‘T. laticinctus Cresson’ and ‘T. morosus Smith’ are both shown to be complexes of sibling species. Reared series have been essential in facilitating the separation of the species in these complexes. An illustrated key is provided to separate all taxa using simple morphological characters. Fourteen of the 23 species have been reared, and all have been found to be restricted to one or a few species of hosts, species of Thyreodon primarily on macroglossine Sphingidae (with one species on Saturniidae) and species of Rhynchophion on sphingine sphingids of the genus Manduca. No two species of these ichneumonids attack the same host caterpillar species, and not all species of macroglossines present in the study area are attacked by species in this genus‐group. Most species are apparently rather rare. Many have only been collected by rearing on a few occasions, other species have been collected at light (six in total) or in Malaise traps (ten in total), or by hand‐netting (20 in total), but no one method collected all of the species present in the principal study area, the Area Conservacion de Guanacaste. The two New World genera Rhynchophion and Thyreodon are found to be related to the Old World genera Dictyonotus and Euryophion, the former of which comprises species that are also sphingid parasitoids, whereas species of the latter attack the caterpillars of other large bombycoid moths, Saturniidae and Eupterotidae. A cladistic analysis shows that Thyreodon is the sister‐lineage to Dictyonotus, and Euryophion is the most basal lineage in the genus‐group. © 2004 The Linnean Society of London, Zoological Journal of the Linnean Society, 2004, 141 , 297–351.     

The suprageneric groups ofthe Pimplinae (Hymenoptera: Ichneumonidae): a cladistic re-evaluationand evolutionary biological study

The phylogenetic relationships of the suprageneric groupsof the ichneumonid subfamily Pimplinae (Hymenoptera) are re‐assessedusing 166 morphological and biological characters for 162 species,representing all of the available described genera and subgenera.The cladistic analysis was repeated using abstracted genera, re‐codedfrom the ­initial set of species, as terminal taxa. Thetopology of the resulting cladograms was similar. In the first (primary) analysisseveral genera (including Neotheronia, Itoplectis, Dolichomitus, Dreisbachia, Polysphincta, Oxyrrhexis and Zonopimpla)were not retrieved as monophyletic groups; however, all except thelast were found to be monophyletic in the second analysis. Theseresults suggest that using abstracted taxa may force a ‘falsemonophyly’ on the preselected groups. Thus we reject theuse of such abstractions, preferring instead to use exemplar speciesthat together show much of the variation that occurs within a hypothesizedgenus. Within the Pimplinae three major groupings were recognized,the Delomeristini (including the Perithoini syn. nov.) , thePimplini and the Ephialtini. Within the Pimplini, two generic groupswere recovered, the Xanthopimpla and Pimpla genus‐groups,but a third postulated group, the Theronia genus‐group, wasfound to be paraphyletic. Within the Ephialtini five groups wererecognized, the Pseudopimpla, Alophosternum, Camptotypus, Ephialtes and Sericopimpla genus‐groups.The spider parasitizing complex of genera (the Polysphincta genus‐complex)was found to nest within the Sericopimpla genus‐group confirmingthe placement of Polysphinctini as a synonym of Ephialtini. Problemswith the status of some existing genera are highlighted, but formalnomenclatural changes are not proposed. The ancestral Pimplinaeare hypothesized to have been solitary ectoparasitic idiobiontson weakly concealed immature Hymenoptera. The major radiations withinthe Pimplinae are shown as: (1) a progressive exploitation of cocooned,then weakly cocooned, lepidopterous pupae in the Pimplini leadingto idiobiont endoparasitism; (2) increasing specialization to attackhosts deeply concealed in wood in the Ephialtes genus‐group,and (3) specialization on a variety of cocooned hosts, includingspider egg sacs, leading to koinobiont ectoparasitism of spiders.A brief synopsis of the distribution of the group is given, and somebiogeographical inferences drawn. The group is presumed to haveoriginated and radiated on Laurasia; no evidence for trans‐Antarcticrelationships can be found. © 2002 The LinneanSociety of London, Zoological Journal of the Linnean Society,2002, 136 , 421?485     

An evaluation of the taxonomic distinctness of two Geonoma macrostachys (Arecaceae) varieties based on intersimple sequence repeat (ISSR) variation

The latest taxonomic account for the palms of the Amazon recognizes two common and widespread varieties of Geonoma macrostachys (Arecaceae) in western Amazonia: acaulis and macrostachys . These varieties are joined by intermediates, which obscure their taxonomic boundaries. An evaluation of the genetic distinctness between G. macrostachys varieties at a local and regional scale is presented. Thirty-one G. macrostachys individuals were randomly sampled from four Peruvian tropical moist forests. Twenty-seven intersimple sequence repeat (ISSR) primers were used, and all clear and reproducible bands were scored and analysed. Of the 99 ISSR bands produced, 51.52% were polymorphic. Nei's gene diversity value ( H ) was 0.2274 and Shannon's information index ( I ) was 0.3237. Clustering, ordination, and analyses of molecular variance (AMOVAs) suggested a lack of genetic distinctness between varieties at the regional level. Individuals clustered by geographical provenance, and two main groups were identified. A significant genetic differentiation between sympatric varieties occurred only in the northern locality (Φ_ST = 0.359, P  = 0.000). A hierarchical AMOVA revealed that the genetic diversity in G. macrostachys mainly lies between localities (76.58%). Mantel's test revealed no significant correlation between the geographical and genetic distances between individuals. We do not support the recognition of the two taxonomic varieties studied.  © 2007 The Linnean Society of London, Botanical Journal of the Linnean Society , 2007, 153 , 381–392.     

Successive cambia in Aizoaceae: products and process

The transverse and longitudinal sections of the stems and roots of 11 genera of Aizoaceae, representing a wide range of growth forms from hard fibrous stems to fibre‐free roots, were studied using light microscopy and scanning electron microscopy. In most of the genera, fibres are the first xylary product of each vascular cambium, followed by vessels in a parenchyma background. Variations on this pattern help to prove that fibres are produced by vascular cambia, except in Ruschia and Stayneria, in which both the lateral meristem and the vascular cambia produce fibres. Cylinders of conjunctive tissue parenchyma that alternate with the vascular cylinders are produced by the lateral meristem. The concept that the lateral meristem gives rise to the vascular cambia and secondary cortex is supported by photographic evidence. Radial divisions occur in the origin of the lateral meristem, and then again as vascular cambia arise from the lateral meristem; these radial divisions account for storeying in fibres and conjunctive tissue. Raylessness characterizes all Aizoaceae studied, with the exception of Tetragonia, which also differs from the remaining genera by having vasicentric axial parenchyma, a scattering of vessels amongst fibres, and the presence of druses instead of raphides. Several vascular cambia are typically formed per year. Several vascular cambia are active simultaneously in a given stem or root. Roots have fewer fibres and more abundant conjunctive tissue parenchyma than stems. Successive cambia result in an ideal dispersion of vascular tissue with respect to water and photosynthate storage and retrieval capabilities of the parenchyma, and to liana stem plans. The distribution and relative abundance of fibres, vessels, secondary phloem, and conjunctive tissue parenchyma relate primarily to habit and are not a good source of systematic data, with the probable exception of Tetragonia. The general pattern of lateral meristem and vascular cambial ontogeny is the same as in other families of the core Caryophyllales, although the patterns of the tissues produced are diverse. © 2007 The Linnean Society of London, Botanical Journal of the Linnean Society, 2007, 153 , 141–155.     

Molecular evidence for phylogenetic relationships of Jacquemontia reclinata House (Convolvulaceae) – a critically endangered species from south Florida

Jacquemontia reclinata House (Convolvulaceae) is a federally listed endangered species endemic to coastal strand habitat of south-eastern Florida. In order to identify the closest relatives of J. reclinata , a phylogenetic reconstruction was performed based on nucleotide sequence data from the internal transcribed spacer region of nuclear ribosomal DNA and from the trnH-psbA intergenic spacer of chloroplast DNA. The three putative relatives of J. reclinata and the majority of Jacquemontia Choicy species known to occur in the Caribbean Islands were included. The strict consensus tree concurs with previous morphological studies, indicating that J. reclinata is closely related to the Caribbean species J. cayensis Britton, J. curtisii Hallier f., and J. havanensis (Jacq.) Urb. These three species and J. reclinata form an unresolved clade. Nucleotide divergence within this clade is low, suggesting that the group is recent, perhaps diversifying after the latest glacial period. These taxa need to be studied further using population-level DNA markers. Most species endemic to the Caribbean Basin form a strongly supported clade. Our phylogeny supports Convolvulus nodiflorus Desr. as part of Jacquemontia . In addition, J. ovalifolia (West) Hallier f. ssp. sandwicensis (A. Gray) K.R. Robertson is sister to the Antillean endemic J. solanifolia (L.) Hallier f. © 2007 The Linnean Society of London, Botanical Journal of the Linnean Society , 2007, 154 , 443–454.     

A revision of Leptopontia T. Scott (Gopepoda: Harpacticoida) with description of six new species

The presumed amphiatlantic distribution of Leptopontia cwmicauda T. Scott, 1902 (Copepoda: Harpacticoida) is reviewed and the species being redescribed on the basis of a single male from the Isle of Sylt. Examination of other material previously attributed to L. curvicauda , collected in South Carolina and a wide range of localities in northwestern Europe, resulted in the discovery of four new, morphologically similar species: L. dovpori sp. no v., L. flandrica sp. no v., L. punctata sp. nov. and L. americana sp. Nov . In addition, two new species, L. mediterranea sp. Nov . and L. breviarticulata sp. Nov . are described from the Mediterranean and the Galapagos archipelago, respectively. L. curvicauda sensu Marinov (1971) and sensu Apostolov (1973) from the Black Sea and sensu Klie (1950) from Helgoland are regarded as species inquirendae. A revised diagnosis of the genus Leptopontia T. Scott is presented.     

A molecular phylogeny and a revised classification of tribe Lepisoreae (Polypodiaceae) based on an analysis of four plastid DNA regions

Phylogenetic relationships within the palaeotropical tribe Lepisoroideae (Polypodiaceae) were investigated by studying sequence variation of four plastid DNA regions: rbcL, rps4 plus rps4‐trnS IGS, trnL intron plus trnL‐F IGS, rbcL‐atpB IGS plus part of atpB. In total, over 4000 nucleotides were sequenced for 39 species. Seven well‐supported clades were found in the analyses of the combined data set. We provide a new classification of Lepisoroideae by integrating phylogenetic results and known variation of morphological characters. The two small genera Neocheiropteris and Tricholepidium are supported as monophyletic, the genus Paragramma is resurrected and the genera Lepisorus, Neolepisorus, Lemmaphyllum and Lepidomicrosorium are re‐circumscribed. We proposed 14 new combinations, among which Caobangia is treated as a synonym of Lemmaphyllum. A key for identifying the recognized genera is presented. © 2010 The Linnean Society of London, Botanical Journal of the Linnean Society, 2010, 162 , 28–38.     

The systematic importance of anatomical data in Gagea (Liliaceae) from the Flora Iranica area

Anatomical features of basal leaves, pedicels and tepals of 22 species of Gagea belonging to four sections (Platyspermum, Plecostigma, Gagea and Didymobulbos) are investigated. Anatomical characters are mapped onto a molecular phylogenetic tree and their evolution is evaluated. The systematic importance of the anatomical characters is discussed. Anatomical characters are more systematically useful in the Irano‐Turanian taxa than in Euro‐Siberian taxa. The presence of collenchyma and/or sclerenchyma and the pentagonal outline of the transverse section of the basal leaf is found in Irano‐Turanian taxa of section Platyspermum and is mostly absent in Euro‐Siberian taxa. A diagnostic key based on combined anatomical characters is provided. The level of variation in anatomical characters is greater in the basal leaf than the pedicel and lowest in the tepals. Convergent evolution in anatomical characters is associated with ecological shifts between sunny, open, dry habitats and closed, humid habitats. © 2010 The Linnean Society of London, Botanical Journal of the Linnean Society, 2010, 164 , 155–177.     

Cranial osteology and phylogenetic position of the theropod dinosaur Proceratosaurus bradleyi (Woodward, 1910) from the Middle Jurassic of England

The cranial osteology of the small theropod dinosaur Proceratosaurus from the Bathonian of Minchinhampton, England, is described in detail, based on new preparation and computed tomography (CT) scan images of the type, and only known, specimen. Proceratosaurus is an unusual theropod with markedly enlarged external nares and a cranial crest starting at the premaxillary–nasal junction. The skull is highly pneumatic, with pneumatized nasals, jugals, and maxillae, as well as a highly pneumatic braincase, featuring basisphenoid, anterior tympanic, basipterygoid, and carotid recesses. The dentition is unusual, with small premaxillary teeth and much larger lateral teeth, with a pronounced size difference of the serrations between the mesial and distal carina. The first dentary tooth is somewhat procumbent and flexed anteriorly. Phylogenetic analysis places Proceratosaurus in the Tyrannosauroidea, in a monophyletic clade Proceratosauridae, together with the Oxfordian Chinese taxon Guanlong. The Bathonian age of Proceratosaurus extends the origin of all clades of basal coelurosaurs back into the Middle Jurassic, and provides evidence for an early, Laurasia‐wide, dispersal of the Tyrannosauroidea during the late Middle to Late Jurassic. © 2009 The Linnean Society of London, Zoological Journal of the Linnean Society, 2009.