From ‘cryptic species’ to integrative taxonomy: an iterative process involving DNA sequences,morphology, and behaviour leads to the resurrection of Sepsis pyrrhosoma (Sepsidae: Diptera)

Tan, D. S. H., Ang, Y., Lim, G. S., Ismail, M. R. B. & Meier, R. (2010). From ‘cryptic species’ to integrative taxonomy: an iterative process involving DNA sequences, morphology, and behaviour leads to the resurrection of Sepsis pyrrhosoma (Sepsidae: Diptera). —Zoologica Scripta, 39, 51–61. The increased availability of DNA sequences has led to a surge of ‘cryptic species’ in the literature. These units are usually proposed based on finding genetically distinct lineages within species that were initially defined based on morphological characters. However, few authors attempt to confirm whether these ‘cryptic’ units are species and even fewer authors are explicit about which species concept is applied. Here, we use an example from Sepsidae (Diptera) to demonstrate how cryptic species can be validated by an iterative process involving several data sources and an evaluation of the data under different species concepts. A phylogeographic analysis based on 50 specimens for five species of the flavimana group revealed deep mitochondrial splits within Sepsis flavimana which was suggestive of a cryptic species. We resolve the initial conflict between DNA sequences and morphology by adding new morphological data as well as behavioural evidence and tests for reproductive isolation. One cryptic species is confirmed and Sepsis pyrrhosoma, a former synonym of S. flavimana, is here shown to be a valid species under most species concepts. We can thus document that the same data can lead to similar conclusions under conflicting concepts once different kinds of data are integrated.     

Eunotia amazonica sp. nov. (Bacillariophyta), a common stalk-forming species from the Rio Negro basin (Brazilian Amazon)

A new stalk-forming diatom was observed at high relative abundances on periphytic samples collected in the Rio Negro hydrographic basin (Brazilian Amazon) and is here described using light and scanning electron microscopy. We also present ecological preferences of the new species. Eunotia amazonica sp. nov. co-dominated periphytic samples collected during the rainy seasons of 2013 and 2014 near the city of Manaus (Amazonas, Brazil). The main diagnostic feature of the new species is the stalk-forming growth form (‘Cymbella-like’) illustrated here for the first time in the genus Eunotia Ehrenberg. Previous reports on growth forms in common European databases for this genus included colonial (‘ribbon-like’) but also ‘mobile’, ‘fixed by pads’ or ‘without structures of fixation’. We demonstrated that the three dominant Eunotia species in periphytic samples from the Rio Negro all exhibited distinct ‘growth forms’ or habits: Eunotia amazonica sp. nov. (stalked), Eunotia intricans Metzeltin & Lange-Bertalot (ribbon-like) and Eunotia rabenhorstiana (Grunow) Hustedt (branched-arborescent). The high diversity of species, many of which are unknown to science, as well as the poorly known life-forms and habits of the Eunotiaceae in the region, partially prevent the use of metrics based on life-form to assess ecological changes. Generic assumptions based on robust statistical methods may obscure reality and lead to biased conclusions of diatom community changes in poorly explored regions such as Neotropical freshwater rivers, where the Eunotiaceae are largely dominant, particularly in the Amazon basin.     

Warneckea cordiformis sp. nov. (Melastomataceae–Olisbeoideae) from a coastal dry forest in northern Mozambique

Described and illustrated is Warneckea cordiformis R. D. Stone, an evidently localized endemic of coastal dry forest in Mozambique's Cabo Delgado Province. In ‘Flora Zambesiaca’ the new species would key to W. sansibarica (Taub.) Jacq.‐Fél., from which it is readily distinguished by the much smaller, ovate to cordiform leaves and white, short‐pedicellate flowers. Because of its evidently very limited occurrence as well as on‐going anthropogenic threats, Warneckea cordiformis is here assessed as ‘Critically Endangered’ (CR) B1a,b(iii) according to IUCN criteria. A key is provided to the Mozambican species of Warneckea.     

Presence of Lythrum salicaria enhances the bodyguard effects of the parasitoid Asecodes mento for Filipendula ulmaria

This paper reports significant effects of a co‐occurring plant species (Lythrum salicaria, Lythraceae) on the reproductive success of the perennial herb Filipendula ulmaria (Rosaceae). We studied 15 Filipendula populations in the Skeppsvik Archipelago; seven of which were monospecific and eight mixed with Lythrum. All the Filipendula populations studied harbored the chrysomelid beetle Galerucella tenella, and in 2005 seed set was strongly negatively correlated with the percentage leaf area consumed. Moreover, data from 2004 showed that 25–100% of the G. tenella larvae were parasitized by the hymenopteran parasitoid Asecodes mento, and we found a strong cascading top‐down effect of parasitism in 2004 on Filipendula seed set in 2005. In 2004, parasitism (at the population level) was negatively correlated with percentage leaf area consumed and positively correlated with seed set in 2005. The parasitoid Asecodes also parasitized G. calmariensis, which is monophagous on Lythrum. Mixed populations of Filipendula and Lythrum supported higher densities of their shared ‘bodyguard’Asecodes. Further, Y‐tube bioassays showed that floriferous Filipendula attracted more than twice as many gravid Asecodes females as floriferous Lythrum. Taken together, these findings suggest that coexistence of the two plants results in ‘associational resistance’ for Filipendula and ‘associational susceptibility’ for Lythrum. This scenario was supported for Filipendula since, for this species, we found lower leaf consumption followed by higher seed production in mixed than in monospecific populations. Considered together, our results show that bodyguards may increase the reproductive fitness of a perennial herb, and that the strength of the cascading ‘bodyguard’ effect can be strongly influenced by co‐occurring plants through ‘apparent competition’. This is the first paper to demonstrate that, in the wild, plant species may use odors to compete for ‘bodyguards’, thereby causing asymmetrical ‘apparent competition’ between the herbivores involved. Our data emphasize the need to consider community factors in studies of trophic interactions.     

Sticky predators: a comparative study of sticky glands in harpactorine assassin bugs (Insecta: Hemiptera: Reduviidae)

Zhang, G. and Weirauch, C. 2011. Sticky predators: a comparative study of sticky glands in harpactorine assassin bugs (Insecta: Hemiptera: Reduviidae). —Acta Zoologica (Stockholm) 00 : 1–10. For more than 50 years, specialized dermal glands that secrete sticky substances and specialized setae have been known from the legs of New World assassin bugs in the genus Zelus Fabricius (Reduviidae: Harpactorinae). The gland secretions and specialized ‘sundew setae’ are involved in enhancing predation success. We here refer to this predation strategy as ‘sticky trap predation’ and the specialized dermal glands as ‘sticky glands’. To determine how widespread sticky trap predation is among Reduviidae, we investigated taxonomic distribution of sticky glands and sundew setae using compound light microscopical and scanning electron microscopical techniques and sampling 67 species of Reduviidae that represent 50 genera of Harpactorini. We found sticky glands in 12 genera of Harpactorini and thus show that sticky trap predation is much more widespread than previously suspected. The sticky glands vary in shape, size and density, but are always located in a dorsolateral position on the fore tibia. Sundew setae are present in all taxa with sticky glands with the exception of Heza that instead possesses unique lamellate setae. The sticky trap predation taxa are restricted to the New World, suggesting a New World origin of this unique predation strategy.     

Geographical gradients of species richness: a test of the water‐energy conjecture of Hawkins et al. (2003) using European data for five taxa

Aims We present an analysis of grid‐based species‐richness data for European plants, mammals, birds, amphibians and reptiles, designed to test the proposition of Hawkins et al. (2003a ) that the single best factor describing richness variation switches from the water regime to the energy regime in the mid‐latitudes and that the ‘breakpoint’ is related to the physiological character of the taxa. We go on to develop subregional models showing the extent to which regional model fits vary as a function of the extent of the study system, and compare the relative performance of ‘water’, ‘energy’ and ‘water–energy’ models of richness for southern, northern and pan‐European models. Location Western Europe. Methods We use atlas data comprising species range data for 187 species of mammals, 445 species of breeding birds, 58 amphibians, 91 reptiles and 2362 plant species, inserted into a c. 50 × 50 km grid cell system. We used 11 modelled climate variables, averaged for the period 1961–90. Statistical analyses were carried out using generalized additive models (GAMs), with splines simplified to a maximum of four degrees of freedom, and we tested for spatial autocorrelation using Moran's I values obtained at 10 different distance intervals. We selected favoured models on the grounds of deviance explained combined with a simple parsimony criterion, such that we selected either: (1) the best two‐variable energy, water or water–energy model, or (2) a four‐variable water–energy model, where the latter improved on the best two‐variable model by a minimum of 5% deviance explained. Results Threshold energy values, at which richness shows a transition from an increasing to a decreasing function of annual solar radiation, were identified for all taxa apart from reptiles. We found conditional support for the switch from dominance of water variables (southern models) to energy variables (northern models). Our favoured models switched between ‘water’ and ‘energy’ for mammals, and between ‘energy’ and ‘water–energy’ for birds, depending on whether we used data of pan‐European extent, southern or northern subsets. Deviance explained in our favoured models varied from 15% (birds, southern Europe) to 72% (amphibians, northern Europe), i.e. ranging from very poor to good fits with the data. Comparison with previous work indicates that our models are generally consistent with (if sometimes weaker than) previous findings. Main conclusions Our models are incomplete representations of factors influencing macro‐scale richness patterns across Europe, taking no explicit account of, for example, topographic variation, human influences or long‐term climatic variation. However, with the exception of birds, for which only the northern model attains over one‐third deviance explained, the models show that climate can account for meaningful proportions of the deviance. We find general support for considering water and energy regimes together in modelling species richness, and for the proposition that water is more limiting in southern Europe and energy in the north. Our analyses demonstrate the sensitivity of model outcomes to the geographical location and extent of the study system, illustrating that simple curve‐fitting exercises like these, particularly if based on regions with the complex history and geography characteristic of Europe, are unlikely to provide the basis for global, predictive models. However, such exercises may be of value in detecting which aspects of water and energy regimes may be of most importance in refining independently generated global models for regional application.     

Novitates Gabonensis 79: Hymenostegia elegans and H. robusta spp. nov. (Leguminosae–Caesalpinioideae) from Gabon

We have observed among the holdings of Hymenostegia (Leguminosae: Caesalpinioideae) in several major herbaria that many of the specimens determined as H. klainei Pierre ex Pellegr. are not identified correctly and instead represent undescribed taxa. We speculate that the misidentifications may be a direct consequence of the sole use of leaf characters to distinguish species in the dichotomous keys of two major regional treatments of the genus. Two such previously unrecognised taxa, both new species from Gabon, Hymenostegia elegans Wieringa and Mackinder and Hymenostegia robusta Wieringa and Mackinder are described here accompanied by a distribution map, illustrations and conservation assessments. Both species have a limited distribution area and are assessed as ‘Vulnerable’ and ‘Endangered’, respectively. This publication brings the total number of species in Hymenostegia s.s. to nine.     

Tropical Monodominance: A Preliminary Test of the Ectomycorrhizal Hypothesis1

This study reports results from the first explicit test of the ectomycorrhizal hypothesis for tropical monodominance in the Ituri Forest of the Democratic Republic of Congo (formerly Zaire), where the canopy tree Gilbertiodendron dewevrei forms large, monospecific stands. To test the hypothesis that ectomycorrhizae are important to the success of dominant species, we surveyed the mycorrhizal status of dominant species, as well as other common, but not dominant, species in the forest. The survey reveals that two dominant species, Gilbertiodendron dewevrei and Julbernardia seretii, form ectomycorrhizae and vesicular-arbuscular mycorrhizae, while Cynometra alexandri, another dominant, forms only vesicular-arbuscular mycorrhizae. These results, along with those of other species in this and other forests, are discussed within the context of the ectomycorrhizal hypothesis for tropical mondominance. This study demonstrates that the relationship between EM and tropical monodominance is more complex than has been previously recognized.     

Typification and redelimitation of Nepenthes alata with notes on the N. alata group,and N. negros sp. nov. from the Philippines

In the course of studies to typify what has been regarded as the most widespread and common of the endemic Philippines species of Nepenthes, N. alata Blanco, we were able to review the morphological variation in what we previously regarded as a polymorphic species. This led us to redelimit that species in a narrower sense, to resurrect N. graciliflora Elmer, and to recognise N. negros sp. nov., here assessed as ‘Critically Endangered’ (CR) using the IUCN standard. The Nepenthes alata group is characterised and a key to its species is provided.     

Species names and metaphyly: a case study in Discodorididae (Mollusca, Gastropoda, Euthyneura, Nudibranchia, Doridina)

Dayrat, B. & Gosliner, T. M. (2005). Species names and metaphyly: a case study in Discodorididae (Mollusca, Gastropoda, Euthyneura, Nudibranchia, Doridina) —Zoologica Scripta, **, ***–***. Absence of resolution in phylogenetic trees, or metaphyly, is a common phenomenon. It mainly results from the fact that each data set has its own limit and can hardly be expected to reconstruct alone an entire hierarchy. Because metaphyly helps point out which regions of a tree merit further investigation, one should not avoid metaphyly but rather should try to detect it by addressing carefully node reliability. In this paper we explore the implication of metaphyly for species names. We present a phylogenetic analysis of Discodorididae (Mollusca, Gastropoda, Nudibranchia, Doridina), with an emphasis on relationships among species of Discodoris and its traditionally close ‘allies’ such as Peltodoris and Anisodoris. We demonstrate that some species must be transferred to different discodoridid subclades with which they share synapomorphies, but that many species form a metaphyletic group at the base of Discodorididae, and therefore cannot be placed in any taxon of genus level. We demonstrate that the current International Code of Zoological Nomenclature does not allow taxonomists to handle this situation because it requires selecting a taxon name of genus rank for every species binomial. Then we evaluate the results provided by new forms of species names, both in a rank‐based system, such as the current nomenclature, and a rank‐free system. All solutions considered would cause radical changes to the ‘spirit’ of the current ICZN (and, by extension, to the other current codes). In a rank‐free system of nomenclature, such as the PhyloCode, the best result is obtained with an epithet‐based form that does not mention supra‐specific relationships. Under this method, official species names would take the form ‘boholiensis Bergh, 1877’, although page numbers and letters can be added for uniqueness purposes. Taxonomists would then be free to add supra‐specific taxon names in ‘common’ species names, such as Discodorididae boholiensis Bergh, 1877 or simply Discodorididae boholiensis. Here we wish to stimulate discussion of a problem that we believe merits wide debate: absence of resolution in phylogenetic reconstruction and its impact on species nomenclature.     

Sperm morphology of five species of Colostethus (Anura, Dendrobatidae) from Brazil, with phylogenetic comments

We describe the sperm ultrastructure of five species of Colostethus from Brazil. The general structures of the spermatozoa (acrosomal complex and flagellar apparatus) were similar to species within the Bufonoidea. Colostethus brunneus, Colostethus sp. (aff. trilineatus), Colostethus nidicola and Colostethus sp. had biflagellated spermatozoa, whereas the spermatozoa of Colostethus stepheni had a single flagellum, a characteristic previously unknown for this genus. In addition, the spermatozoa of this species showed some mitochondria within the thick, undulating membrane. These characteristics are apparently common to dendrobatid species that have a single flagellum. Based on these findings, we tentatively consider biflagellarity to be an apomorphic condition in the Dendrobatidae. In addition, the results described here do not support the proposed regrouping of the ‘brunneus’ and ‘alagoanus’ groups in a monophyletic ‘trilineatus’ group.     

Intrinsic competition between two secondary hyperparasitoids results in temporal trophic switch

Interspecific competition amongst parasitoids is important in shaping the evolution of life‐history strategies in these insects as well as community structure. Competition for hosts may occur between adult female parasitoids (‘extrinsic’ competition) or their progeny (‘intrinsic’ competition). Here, we examined intrinsic competition between two solitary secondary hyperparasitoids, Lysibia nana and Gelis agilis in cocoons of a primary parasitoid, Cotesia glomerata. Each species was allowed to sting hosts previously parasitized by the other at 24 h time intervals over the course of 144 h (6 days). When hosts were attacked simultaneously, neither species was dominant although the species to attack first won most encounters when it had a 24–48 h head start. However, after this time there was dramatic shift in the outcome with G. agilis dominating in all hosts > 72‐h old, regardless of which species had parasitized C. glomerata first. G. agilis larvae, which initially had competed with L. nana for control of C. glomerata resources, began attacking the larvae of L. nana, whereas L. nana rejected hosts with older G. agilis larvae or pupae. Effects of multiparasitism also affected the development time and adult mass of the winning parasitoid. Our results reveal a shift in the trophic status of G. agilis from C. glomerata (in younger hosts) to L. nana (in older hosts), the first time such a phenomenon has been reported in parasitoids.     

Cultivation of a vampire: ‘Candidatus Absconditicoccus praedator’

Halorhodospira halophila, one of the most-xerophilic halophiles, inhabits biophysically stressful and energetically expensive, salt-saturated alkaline brines. Here, we report an additional stress factor that is biotic: a diminutive Candidate-Phyla-Radiation bacterium, that we named ‘Ca. Absconditicoccus praedator’ M39-6, which predates H. halophila M39-5, an obligately photosynthetic, anaerobic purple-sulfur bacterium. We cultivated this association (isolated from the hypersaline alkaline Lake Hotontyn Nur, Mongolia) and characterized their biology. ‘Ca. Absconditicoccus praedator’ is the first stably cultivated species from the candidate class-level lineage Gracilibacteria (order-level lineage Absconditabacterales). Its closed-and-curated genome lacks genes for the glycolytic, pentose phosphate- and Entner–Doudoroff pathways which would generate energy/reducing equivalents and produce central carbon currencies. Therefore, ‘Ca. Absconditicoccus praedator’ is dependent on host-derived building blocks for nucleic acid-, protein-, and peptidoglycan synthesis. It shares traits with (the uncultured) ‘Ca. Vampirococcus lugosii’, which is also of the Gracilibacteria lineage. These are obligate parasitic lifestyle, feeding on photosynthetic anoxygenic Gammaproteobacteria, and absorption of host cytoplasm. Commonalities in their genomic composition and structure suggest that the entire Absconditabacterales lineage consists of predatory species which act to cull the populations of their respective host bacteria. Cultivation of vampire : host associations can shed light on unresolved aspects of their metabolism and ecosystem dynamics at life-limiting extremes.     

Spiradiclis jingxiensis sp. nov. (Rubiaceae) from Guangxi,China

The new species Spiradiclis jingxiensis R. J. Wang is described here. It is similar to S. danxiashanensis with respect to its prostrate habit, small leaves, and terminal inflorescence with 1–3 salverform flowers, but is readily distinguished by pinkish flowers, and included stamens and stigmas in long‐ and short‐styled flowers. The conservation status of the new species was preliminarily assessed as ‘EN’ according to IUCN categories and criteria.     

CYTOGENETICS OF RUBUS. II. CYTOLOGICAL STUDIES OF THE VARIETIES ‘YOUNG,’ ‘BOYSEN,’ AND RELATED FORMS

Thompson , Maxine M. (U. California, Davis.) Cytogenetics of Rubus. II. Cytological studies of the varieties ‘Young,’ ‘Boysen’ and related forms. Amer. Jour. Bot. 48(8): 667–673. Illus. 1961.—Chromosome numbers are given for the trailing blackberry varieties, ‘Young’ (2n = 49), ‘Boysen’ (2n = 49), ‘Nectar’ (2n = 49) and for related forms which include the parents of ‘Young,’ ‘Phenomenal’ (2n = 42) and ‘Mayes’ (2n = 56), and 3 cytologically resynthesized ‘Young’ plants (2n = 49) as a basis for interpreting the postulated origin of ‘Young.’ Cytological evidence substantiated the conclusion that ‘Young’ is a hybrid between ‘Phenomenal’ and ‘Mayes.’ Contributions to the understanding of genomic relationships in Rubus are offered from detailed analyses of meiosis in ‘Phenomenal,’ ‘Mayes,’ ‘Young,’ and ‘Boysen.’ ‘Phenomenal’ and ‘Mayes’ both had a very regular meiosis. ‘Young,’ as well as ‘Boysen,’ showed a greater degree of chromosome association than either parent of ‘Young.’ Meiotic behavior in ‘Boysen’ presented a close parallel to that of ‘Young’ which, correlated with morphological similarities and the same 2n chromosome number, suggests a similar origin. The mode of reproduction in ‘Young’ and ‘Boysen’ was found to be sexual on the basis of morphological variation in the open-pollinated (selfed) progeny, the varying aneuploid somatic chromosome numbers in these progeny (2n = 32–54) and aneuploid chromosome numbers in hybrids having either variety as one parent. The productiveness of ‘Young’ and ‘Boysen’ in commercial plantings and their successful utilization in breeding programs indicate a high fertility regardless of their having an odd multiple of the basic number. It is concluded that the production of balanced euploid gametes is not necessarily a criterion of fertility, at least not at this high level of ploidy.     

Reproductive potential and lifetime potential fecundity of the freshwater amphipods Gammarus fossarunt and G. roeseli in Austrian streams and rivers

• 1 Fecundity of Gammarus fossarum populations at six stream sites (S1-S6) and G. roeseli populations at two sites (S5 and S6) was studied monthly during 1985–1988, distinguishing seven morphological stages of embryonic development. Mean survival of G. fossarum eggs was 65% (60–70%) in nature and 60% (57–63%) in the laboratory; egg survival of G. roeseli was 52% (46–58%) in nature and 41% (35–47%) in the laboratory. Regressions of egg numbers per clutch against body wet weight (WWT) decreased significantly for egg developmental stages 2 to 7 (hatching).
• 2 In stream populations, ovigerous females of G. fossarum were absent in October (six sites) and November (five sites); ovigerous G. roeseli were usually absent from October until March.
• 3 Overall mean egg volume (EV) increased significantly from 0,08 ± 0.001 mm³ and 0.075 ± 0.001 mm³ for stage 2 eggs, to 0.174 ± 0.012mm³ and 0.160 ± 0.013 mm³ for stage 6 eggs of G. fossarum and G. roeseli, respectively. The dry weights of stage 2 eggs, stage 6 eggs and neonates (stage 7) were not significantly different, within and between species; mean dry weight was 36 ± 3 μg.
• 4 Egg volumes and fecundity indices (FI, weight-specific number of eggs per clutch) were not significantly different between the same months of four successive years, so the data were pooled to give a single representative ‘year’. At most sites there were marked seasonal fluctuations in these variables. In both species, mean EV was largest for ‘winter’ eggs in December/January and smallest for ‘summer’ eggs in May, EV decreased during some months of the year when FI increased, and vice versa. Mean reproductive effort (RE = EV × FI) declined from high ‘winter’ values to low ‘summer’ values, and this difference was most marked at sites where the major foodstuff available was seasonally limited (autumn-shed tree leaves). Overall (‘annual’) mean RE was also lowest at these sites (S3 and S4) but was some 13% greater at sites where nutrients and food were present in the greatest quantifies (S5 and S6). Specific maximum potential body sizes and hence maximum potential fecundities (fifty-nine eggs for G. fossarum and eighty-seven eggs for G. roeseli) were attained only at S5 and 56. Mean RE was nearly identical for G. fossarum and G. roeseli from the same sites.
• 5 At experimental temperatures (T) in the range 3.8–20.2°C, females of the same body weight carried significantly different egg numbers per clutch. The relationship between FI and T was described by a second-order polynomial. The calculated optimum T was 12.1°C for G. fossarum and 16.3°C for G. roeseli. Interspecific differences were highly significant.
• 6 Theoretical lifetime potential fecundity was approximately 194 eggs for G. fossarum

     

Keraunea gen. nov. (Convolvulaceae) from Brazil

Keraunea Cheek & Simão‐Bianchini gen. nov. (Convolvulaceae) from Brazil is described and illustrated as the third known neuropeltoid genus. It appears allied to the Old World genera of Neuropeltis Wall and Neuropeltopsis Ooststr. in having wind‐dispersed fruits not by enlarged sepals, but subtended by an enlarged papery bract to which the pedicel is adnate, and flowers in which the bracteoles are absent or usually very inconspicuous. Keraunea brasiliensis, the single species thus far known, is here assessed as ‘Endangered’.     

Pyrogeography,historical ecology,and the human dimensions of fire regimes

In our 2011 synthesis (Bowman et al., Journal of Biogeography, 2011, 38 , 2223–2236), we argued for a holistic approach to human issues in fire science that we term ‘pyrogeography’. Coughlan & Petty (Journal of Biogeography, 2013, 40 , 1010–1012) critiqued our paper on the grounds that our ‘pyric phase’ model was built on outdated views of cultural development, claiming we developed it to be the unifying explanatory framework for all human–fire sciences. Rather, they suggest that ‘historical ecology’ could provide such a framework. We used the ‘pyric transition’ for multiple purposes but did not offer it as an exclusive explanatory framework for pyrogeography. Although ‘historical ecology’ is one of many useful approaches to studying human–fire relationships, scholars should also look to political and evolutionary ecology, ecosystems and complexity theories, as well as empirical generalizations to build an interdisciplinary fire science that incorporates human, ecological and biophysical dimensions of fire regimes.     

A chiton without a foot

Abstract: The palaeoloricate ‘polyplacophorans’ are an extinct paraphyletic group of basal chiton‐like organisms known primarily from their fossilized valves. Their phylogenetic placement remains contentious, but they are likely to include both stem‐group Polyplacophora and stem‐group Aplacophora. Candidates for the latter position include ‘Helminthochiton’thraivensis from the Ordovician of Scotland, which we redescribe here through a combined optical and micro‐CT (XMT) restudy of the type material. The 11 specimens in the type series are all articulated, presenting partial or complete valve series as well as mouldic preservation of the girdle armature; they demonstrate a vermiform body plan. The valves are typically palaeoloricate in aspect, but differ in detail from all existing palaeoloricate genera; we hence erect Phthipodochiton gen. nov. to contain the species. The most notable feature of the fossils is the spicular girdle; this is impersistently preserved, but demonstrably wraps entirely around the ventral surface of the animal, implying that a ‘true’ (i.e. polyplacophoran like) foot was absent, although we do not exclude the possibility of a narrow solenogastre‐like median pedal groove having been present. Phthipodochiton thraivensis presents an apparent mosaic of aplacophoran and polyplacophoran features and as such will inform our understanding of the relationship between these groups of extant molluscs. An inference may also be drawn that at least some other palaeoloricates possessed an ‘armoured aplacophoran’ body plan, in contrast to the ‘limpet‐like’ body plan of extant Polyplacophora.