Review of seven-spined <Emphasis Type="Italic">Polynemus</Emphasis> species (Perciformes: Polynemidae) with designation of a neotype for <Emphasis Type="Italic">Polynemus paradiseus</Emphasis> Linnaeus, 1758

 A taxonomic review of seven-spined Polynemus species recognizes two species as valid: P. hornadayi Myers, 1936, currently known only from western Sarawak, Kalimantan, Malaysia, and P. paradiseus Linnaeus, 1758, distributed from India to Thailand and regarded as a senior synonym of P. aureus Hamilton, 1822, P. longifilis Cuvier in Cuvier and Valenciennes, 1829, P. risua Hamilton, 1822, and P. toposui Hamilton, 1822. Polynemus hornadayi differs from P. paradiseus in having a strongly protruded occipital profile (vs. nearly straight in the latter), lower counts of anal fin soft rays (mode 11 vs. 12) and gill rakers (26 vs. 32 or 33), higher counts of pectoral fin rays (18 vs. 17), scales above and below the lateral line (11 and 18 vs. 7 and 11, respectively), and pored lateral line scales (94 vs. 70), the fifth pectoral filament longest (vs. sixth), the fourth pectoral filament longer (extending well beyond the posterior central margin of the caudal fin vs. not reaching posterior central margin), a longer pectoral fin ray (posterior tip of pectoral fin reaching to midpoint of anal fin base vs. not reaching), a deeper maxilla posterior margin (mean 5% of SL vs. 4% of SL), and a well-developed swimbladder (vs. absent).     

Revision of the Indo-West Pacific polynemid fish genus <Emphasis Type="Italic">Eleutheronema</Emphasis> (Teleostei: Perciformes)

A taxonomic revision of the polynemid fish genus Eleutheronema, which is redefined, resulted in three species of the genus being regarded as valid: Eleutheronema rhadinum (Jordan and Evermann, 1902), having to date been treated as a junior synonym of E. tetradactylum (Shaw, 1804) and currently known only from East Asia (China and Japan) where it is endemic; E. tetradactylum, a senior synonym of both Polynemus teria Hamilton, 1822 and Polynemus coecus Macleay, 1878, being a widely distributed Indo-West Pacific species, which ranges from the Persian Gulf to Australia; and E. tridactylum (Bleeker, 1845), distributed in Southeast Asia (Thailand, Malaysia, and Indonesia). Eleutheronema tridactylum is easily distinguished from both E. rhadinum and E. tetradactylum owing to the vomer lacking tooth plates in the former [vs. vomer with 2 deciduous tooth plates (in specimens at least over ca. 70 mm SL) in the latter] and lower counts of pectoral filaments (free lower rays, 3 vs. 4) and gill rakers [mode 8 (range 4–10) vs. 12 (10–17) and 13 (6–18) in E. rhadinum and E. tetradactylum, respectively]. Eleutheronema rhadinum clearly differs from E. tetradactylum in having higher counts of pored lateral line scales [mode 95 (range 82–95) vs. 73 (71–80) in the latter] and higher scale counts above and below the lateral line [12 (11–14) and 16 (15–17), respectively, vs. 10 (9–12) and 14 (13–15), respectively]. Furthermore, E. rhadinum is distinguished from E. tetradactylum by having a dense black pectoral fin [vs. vivid yellow in life (except in specimens over ca. 350 mm SL, pectoral fin dusky-yellow) in the latter]. Intraspecific variations and morphological changes with growth of the three species are also discussed. Received: June 13, 2001 / Revised: October 11, 2001 / Accepted: October 17, 2001     

A new subspecies, Polynemus melanochir dulcis, from Tonle Sap Lake, Cambodia, and redescription of P. m. melanochir Valenciennes in Cuvier and Valenciennes, 1831 with designation of a neotype

 A poorly known threadfin, Polynemus melanochir Valenciennes in Cuvier and Valenciennes, 1831, is redescribed (as P. melanochir melanochir) on the basis of a newly designated neotype and a large number of specimens. Polynemus melanopus Sauvage, 1881 and 3 species commonly regarded as valid, Galeoides microps Steindachner, 1869, P. borneensis Bleeker, 1857, and Trichidion hilleri Fowler, 1905, are all considered junior synonyms of P. m. melanochir. In addition, a new subspecies, P. melanochir dulcis, is described on the basis of 3 specimens. Polynemus m. dulcis differs from P. m. melanochir in having a greater snout length [7% of SL vs. mean 6% (range 5–6%) of SL in the latter] and shorter upper caudal-fin lobe length [35% (34–35%) of SL vs. 39% (35–44%) of SL]. The former is currently known only from Tonle Sap Lake, Cambodia, whereas the latter is known from the Mekong River (Cambodia and southern Vietnam) and Kalimantan (=Borneo; Malaysia and Indonesia). Received: September 27, 2001 / Revised: December 20, 2001 / Accepted: December 29, 2001     

Reclassification of Two <Emphasis Type="Italic">Peronospora</Emphasis> Species Parasitic on <Emphasis Type="Italic">Draba</Emphasis> in <Emphasis Type="Italic">Hyaloperonospora</Emphasis> Based on Morphological and Molecular Phylogenetic Data

On the family Brassicaceae, the causal agent responsible for downy mildew disease was originally regarded as a single species, Peronospora parasitica (now under Hyaloperonospora), but it was recently reconsidered to consist of many distinct species. In this study, 11 specimens of Peronospora drabae and P. norvegica parasitic on the genus Draba were investigated morphologically and molecularly. Pronounced differences in conidial sizes (P. drabae: 14–20 × 12.5–15.5 μm; P. norvegica: 20–29 × 15.5–22 μm) and 7.8% sequence distance between their ITS1-5.8S-ITS2 rDNA sequences confirmed their status as distinct species. Based on ITS phylogeny and morphology (monopodially branching conidiophores, flexuous to sigmoid ultimate branchlets, hyaline conidia and lobate haustoria), the two species unequivocally belong to the genus Hyaloperonospora and not to Peronospora to which they were previously assigned. Therefore, two new combinations, Hyaloperonospora drabae and H. norvegica, are proposed. The two taxa are illustrated and compared using the type specimen for H. norvegica and authentic specimens for H. drabae, which is lectotypified.     

<Emphasis Type="Italic">Humulus japonicus</Emphasis> Accelerates the Decomposition of <Emphasis Type="Italic">Miscanthus sacchariflorus</Emphasis> and <Emphasis Type="Italic">Phragmites australis</Emphasis> in a Floodplain

Humulus japonicus in communities of Miscanthus sacchariflorus and Phragmites australis can grow large enough to overtop other species in the Amsa-dong floodplain. Because of strong winds and the weight of Humulus, plants of M. sacchariflorus and P. australis fell in mid-August and were subject to decomposition under its dense shading. To assess the effects of H. japonicus on nutrient cycling in these communities, we collected fresh samples of M. sacchariflorus and P. australis in litterbags and decomposed them under H. japonicus for 9 months, beginning in August. Biomass and organic contents from M. sacchariflorus during this incubation period were 49–51% and 44–48%, whereas those of P. australis were 49–61% and 32–52%, respectively. Their annual k values were 1.61–1.74 and 1.46–3.54, respectively. Initial N concentrations in M. sacchariflorus and P. australis were 13 and 20 mg g⁻¹, while C:N ratios were 31 and 21, respectively. These results indicate that H. japonicus is responsible for the collapse of M. sacchariflorus and P. australis in August and also accelerates their nutrient cycling through rapid decomposition, thereby increasing nutrient circulation in floodplains.     

Different nutrient use strategies of expansive grasses <Emphasis Type="Italic">Calamagrostis epigejos</Emphasis> and <Emphasis Type="Italic">Arrhenatherum elatius</Emphasis>

Enhanced nitrogen (N) levels accelerate expansion of Calamagrostis epigejos and Arrhenatherum elatius, highly aggressive expanders displacing original dry acidophilous grassland vegetation in the Podyjí National Park (Czech Republic). We compared the capability of Calamagrostis and Arrhenatherum under control and N enhanced treatments to (i) accumulate N and phosphorus (P) in plant tissues, (ii) remove N and P from above-ground biomass during senescence and (iii) release N and P from plant material during decomposition of fresh formed litter. In control treatment, significantly higher amounts of total biomass and fresh aboveground litter were observed in Calamagrostis than in Arrhenatherum. Contrariwise, nutrient concentrations were significantly higher (11.6–14.3 mg N g⁻¹ and 2.3 mg P g⁻¹) in Arrhenatherum peak aboveground biomass than in Calamagrostis (8.4–10.3 mg N g⁻¹ and 1.6–1.7 mg P g⁻¹). Substantial differences between species were found in resorption of nutrients, mainly P, at the ends of growing seasons. While P concentrations in Arrhenatherum fresh litter were twice and three times higher (1.6–2.5 mg P g⁻¹) than in Calamagrostis (0.7–0.8 mg P g⁻¹), N concentrations were nearly doubled in Arrhenatherum (13.1–15.6 mg N g⁻¹) in comparison with Calamagrostis (7.4–8.7 mg N g⁻¹). Thus, the nutrients (N and mainly P) were retranslocated from the aboveground biomass of Calamagrostis probably more effectively in comparison with Arrhenatherum at the end of the growing season. On the other hand, Arrhenatherum litter was decomposed faster and consequently nutrient release (mainly N and P) was higher in comparison with Calamagrostis which pointed to different growth and nutrient use strategies of studied grass species.     

<Emphasis Type="Italic">Johnius</Emphasis> (<Emphasis Type="Italic">Johnius</Emphasis>) <Emphasis Type="Italic">majan</Emphasis> sp. nov., a sciaenid fish (Pisces: Sciaenidae) from Oman,Indian Ocean

Johnius (Johnius) majan sp. nov. is described on the basis of 8 specimens (117–158 mm in standard length) from Oman, Indian Ocean. The new species is distinguished from its congeners by the following combination of characters: black axillary spot on upper pectoral fin base; dorsal soft rays 29–32; anal soft rays 8; scales above lateral line 6, below 11; eye diameter 22.9–28.9% HL; interorbital width 32.0–38.0% HL; gill rakers 5–6 + 15–18 = 21–24; no mental barbel; last well developed pleural rib on 7th vertebra; swim bladder appendages 11; vertebrae 10 + 14 = 24.     

Redescriptions of the Indo-Pacific atherinid fishes <Emphasis Type="Italic">Atherinomorus forskalii</Emphasis>, <Emphasis Type="Italic">Atherinomorus lacunosus</Emphasis>, and <Emphasis Type="Italic">Atherinomorus pinguis</Emphasis>

The Indo-Pacific marine atherinid fishes Atherinomorus forskalii (Rüppell, 1838), Atherinomorus lacunosus (Forster, 1801), and Atherinomorus pinguis (Lacepède, 1803) are redescribed as valid species based on the types and non-type specimens collected throughout the Indo-Pacific. They are similar to each other chiefly in having a wide midlateral band (almost the same or greater than the midlateral scale width), large mouth (posterior tip of upper jaw reaching to or beyond a vertical through anterior margin of pupil), and no distinct tubercle at the posterior end of the dentary. All three species are distinguishable from congeners by those characters. The three species have long been confused with each other or synonymized erroneously as a single species. Atherinomorus forskalii, known from the Red Sea and eastern Mediterranean, differs from Atherinomorus lacunosus and Atherinomorus pinguis in having conspicuous, large endopterygoid teeth, forming obvious tooth ridges. Atherinomorus lacunosus, widely distributed in almost the entire Indo-Pacific, from East Africa to Tonga, north to southern Japan, and south to northern Australia, differs from Atherinomorus pinguis in having a wider midlateral band (the lower margin reaching to almost the center of the fourth scale row at level of the anal fin origin vs. the lower margin reaching to the ventral end of the third scale row in Atherinomorus pinguis) and more numerous midlateral scales (40–44 vs. 38–41 in Atherinomorus pinguis). Atherina morrisi Jordan and Starks, 1906, Hepsetia pinguis mineri Nichols and Roemhild, 1951, Pranesus capricornensis Woodland, 1961, Pranesus maculatus Taylor, 1964, and Pranesus pinguis ruppelli Smith, 1965, are regarded as junior synonyms of Atherinomorus lacunosus. Atherinomorus pinguis is also widely distributed in the Indo-West Pacific, from East Africa to northern Australia and north to southern Japan. Atherina pectoralis Valenciennes, 1835, is considered a junior synonym of Atherinomorus pinguis. Supplementary material to this paper is available in electronic format at     

Chloroplast DNA phylogeography of <Emphasis Type="Italic">Pedicularis</Emphasis> ser. <Emphasis Type="Italic">Gloriosae</Emphasis> (Orobanchaceae) in Japan

Phylogeographic analyses using chloroplast DNA (cpDNA) variation were performed for Pedicularis ser. Gloriosae (Orobanchaceae). Eighty-one plants of 18 populations of 6 species (P. gloriosa, P. iwatensis, P. nipponica, P. ochiaiana, P. sceptrum-carolinum and P. grandiflora) were analyzed. Fifteen distinct haplotypes were identified based on six cpDNA regions: the intergenic spacer between the trnT and trnL 3′exon, trnL 3′exon-trnF, atpB-rbcL, accD–psaI, the rpl16 intron and the trnK region (including the matK gene). Via phylogenetic analyses of the haplotypes, two continental species, P. sceptrum-carolinum and P. grandiflora, were placed at the most ancestral position in the trees. The former species is widely distributed in the Eurasian continent, and the latter is distributed in Far East Asia. Two robust major cpDNA clades (clades I and II) were revealed in the Japanese archipelago, although the statistical values of monophyly of these clades were weak. Clade I included the haplotypes (A-1, A-2, B-1, B-2 and J) of three species (P. gloriosa, P. iwatensis and P. ochiaiana), and Clade II included seven haplotypes (C-D, E-1, E-2 and F-H) of P. nipponica. These results suggest that this series originated on the Eurasian continent and that subsequently populations at the eastern edge of the continent differentiated into the two Japanese lineages. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Induction of pathogenesis-related proteins during biocontrol of <Emphasis Type="Italic">Rhizoctonia solani</Emphasis> with <Emphasis Type="Italic">Pseudomonas aureofaciens</Emphasis> in soybean (<Emphasis Type="Italic">Glycine max</Emphasis> L. Merr.) plants

To investigate the biocontrol effectiveness of the antibiotic producing bacterium, Pseudomonas aureofaciens 63–28 against the phytopathogen Rhizoctonia solani AG-4 on Petri plates and in soybean roots, growth response and induction of PR-proteins were estimated after inoculation with P. aureofaciens 63–28 (P), with R. solani AG-4 (R), or with P. aureofaciens 63–28 + R. solani AG-4 (P + R). P. aureofaciens 63–28 showed strong antifungal activity against R. solani AG-4 pathogens in Petri plates. Treatment with P. aureofaciens 63–28 alone increased the emergence rate, shoot fresh weight, shoot dry weight and root fresh weight at 7 days after inoculation, when compared to R. solani AG-4; P + R treatment showed similar effects. Peroxidase (POD) and β-1,3-glucanase activity of P. aureofaciens 63–28 treated roots increased by 41.1 and 49.9%, respectively, compared to control roots. POD was 26% greater in P + R treated roots than R. solani treated roots. Two POD isozymes (59 and 27 kDa) were strongly induced in P + R treated roots. The apparent molecular weight of chitinase from treated roots, as determined through SDS-PAGE separation and comparison with standards, was about 29 kDa. Five β-1,3-glucanase isozymes (80, 70, 50, 46 and 19 kDa) were observed in all treatments. These results suggest that inoculation of soybean plants with P. aureofaciens 63–28 elevates plant growth inhibition by R. solani AG-4 and activates PR-proteins, potentially through induction of systemic resistance mechanisms.     

Bio-resolution of glycidyl (<Emphasis Type="Italic">o</Emphasis>, <Emphasis Type="Italic">m</Emphasis>, <Emphasis Type="Italic">p</Emphasis>)-methylphenyl ethers by <Emphasis Type="Italic">Bacillus megaterium</Emphasis>

A newly isolated Bacillus megaterium with epoxide hydrolase activity resolved racemic glycidyl (o, m, p)-methylphenyl ethers to give enantiopure epoxides in 84–99% enantiomeric excess and with 21–73 enantiomeric ratios. The (S)-enantiomer was obtained from rac-glycidyl (o or m)-methylphenyl ether while the (R)-epoxides was obtained from glycidyl p-methylphenyl ether. The observations are explained at the level by enzyme-substrate docking studies.     

<Emphasis Type="Italic">Paracobitis nanpanjiangensis,</Emphasis> a new loach (Balitoridae: Nemacheilinae) from Yunnan,China

A new species of the genus Paracobitis, Paracobitis nanpanjiangensis is described from tributaries of the Nanpanjiang River drainage in China. It is distinguished from its congeners, except P. oligolepis and P. wujiangensis, by body scaleless or with rudimentary scales (caudal peduncle with several deeply embedded scales). It can be differentiated from P. wujiangensis by the complete lateral line (vs. incomplete), lower dorsal crest reaching the vertical of origin of anal fin (vs. shorter and higher dorsal crest not reaching the base of anal fin). It is distinguished from P. oligolepis by the following characters: branched dorsal fin with 81/2 (a few 91/2) rays (vs. 91/2), interspaces between bars in front of dorsal fin conspicuously thinner than those behind (vs. vermiform markings), dorsal head without vermiform markings or obscure (vs. clearly vermiform markings on dorsal head), vertebrae 4 + 36–38 (vs. 4 + 39–41).     

<Emphasis Type="Italic">Hirsutella proturicola</Emphasis> sp. nov. isolated from a proturan, <Emphasis Type="Italic">Baculentulus</Emphasis> densus (Protura,Hexapoda)

A new species of Hirsutella, H. proturicola, isolated from a subterranean proturan (Baculentulus densus; Protura, Hexapoda), is described and illustrated. Hirsutella proturicola is characterized by producing monoblastic phialides of 24–51.5 × 2.5–5 μm with a slightly roughened neck, fusiform and curved conidia of 9–18 × 2.5–4 μm that have a truncate base and a papillate projection often capped with sheath-like mucilage, and pluricellular, globose to subglobose chlamydospores of 21–48 × 21–41.5 μm. This species is morphologically and phylogenetically close to H. rostrata, an acaropathogenic species, but can be distinguished from the size of the phialides and the size and shape of the conidia.     

Purification and properties of aminoaldehyde dehydrogenase from <Emphasis Type="Italic">Avena</Emphasis><Emphasis Type="Italic">sativa</Emphasis>

NAD-dependent aminoaldehyde dehydrogenase (AMADH, EC 1.2.1.-) from Avena shoots was purified by DEAE Sephacel, hydroxyapatite, 5′-AMP Sepharose 4B, Mono Q, and TSK-GEL column chromatographies to homogeneity by the criterion of native PAGE. SDS–PAGE yielded a single band at a molecular mass of 55 kDa. IEF studies showed a band with a pI value of 5.3. In contrast to AMADHs from other species, the TSK-GEL chromatography showed that Avena AMADH exists as a monomer in the native state. The purified enzyme catalyzed the oxidations of 3-aminopropionaldehyde (APAL), 4-aminobutyraldehyde (ABAL) N-(3-aminopropyl)-4-aminobutyraldehyde (APBAL), and 4-guanidinobutyraldehyde (GBAL), but not of betaine aldehyde or indoleacetaldehyde. The K _m values for APAL, ABAL, and GBAL were 1.5×10^–6, 2.2×10^–6, and 1.3×10^–5 M, respectively. Although N-terminal amino acid sequence of Avena AMADH could not be determined due to a modification of the amino residue, the sequence of the fragment of AMADH cleaved by V8 protease showed greater similarity to the barley BADH than to the pea AMADH. Electronic Publication     

A direct comparison of the performance of the seaweed biofilters, <Emphasis Type="Italic">Asparagopsis armata</Emphasis> and <Emphasis Type="Italic">Ulva rigida</Emphasis>

The tetrasporophyte of Asparagopsis armata has been previously established as a novel seaweed biofilter for integrated land-based mariculture. The species growth and biofiltration rates were much higher than the values described in the literature for Ulva spp., the most common seaweed biofilter. However, a validation of the advantage of one species over the other requires a study of the performances of these two species in the same system at the same time. In this work, we compared the biofiltration performance and biomass yield of A. armata and Ulva rigida cultivated in the effluents of a fish farm in southern Portugal. Comparisons were performed at different water renewal rates and in two seasons of the year. The maximum total ammonia nitrogen (TAN) removal rates were similar for both species in December (2.7 and 2.8 g TAN m^–2 day^–1 for U. rigida and A. armata, respectively) and higher for A. armata (6.5 g TAN m^–2 day^–1) than for U. rigida (5.1 g TAN m^–2 day^–1) in May. Higher differences were observed when estimating the nitrogen biofiltration through the organic nitrogen yield (N yield) of the biomass produced, particularly in May. This estimate is directly related with the biomass yield and the N content in the tissue which were always higher for A. armata than for U. rigida. In December, the maximum biomass yields were 71 g dry weight (DW) m^–2 day^–1 for A. armata and 44 g DW m^–2 day^–1 for U. rigida, while in May, the yield of A. armata was 125 g DW m^–2 day^–1 and of U. rigida was 73 g DW m^–2 day^–1. This study confirmed that A. armata is indeed a more efficient biofilter than U. rigida. To the best of our knowledge, the production rates reported here are the highest ever reported for macroalgae cultivated in tanks.     

Phylogenetic,Inter, and Intraspecific Sequence Analysis of <Emphasis Type="Italic">spo0A</Emphasis> Gene of the Genus <Emphasis Type="Italic">Geobacillus</Emphasis>

In this work, the variability of spo0A gene in the genus Geobacillus and applicability of this gene for the taxonomy within this genus were evaluated. The protein Spo0A is the master regulator of the endospore-forming process in the all endospore-forming bacteria. Geobacillus genus-specific primers GEOSPO were designed based on the sequences of Geobacillus spo0A gene available through the public databases. Inter and intraspecific variability of Geobacillus spo0A gene was determined after sequencing of the GEOSPO-PCR products. Geobacillus spo0A sequence analysis showed that three species—Geobacillus thermodenitrificans, G. stearothermophilus, and G. jurassicus—could be easily identified. Similarity between the sequences of these species and the other species were in the range of 83.3%–92.0%. In contrast, intraspecific similarity of G. thermodenitrificans and G. stearothermophilus was high—above 99.0%. Similarity of spo0A sequences of G. subterraneus–G. uzenensis species cluster also matched this interval. Intercluster similarity between G. lituanicus–G. thermoleovorans–G. kaustophilus–G. vulcani and G. thermocatenulatus–G. gargensis–G. caldoxylosilyticus–G. toebii–G. thermoglucosidasius species clusters, as well as interspecific similarity within these two clusters was in the range of the intraspecific similarity determined for G. thermodenitrificans and G. stearothermophilus. It was also determined that spo0A cannot be used as the phylogenetic marker for the genus Geobacillus.     

Anatomical changes induced by increasing NaCl salinity in three fodder shrubs, <Emphasis Type="Italic">Nitraria retusa</Emphasis>, <Emphasis Type="Italic">Atriplex halimus</Emphasis> and <Emphasis Type="Italic">Medicago arborea</Emphasis>

Nitraria retusa and Atriplex halimus (xero-halophytes) plants were grown in the range 0–800 mM NaCl while Medicago arborea (glycophyte) in 0–300 mM NaCl. Plants were harvested after 120 days of salt-treatment. The present study was designed to study the effect of salinity on root, stem and leaf anatomy, water relationship, and plant growth in greenhouse conditions. Salinity induced anatomical changes in the roots, stems and leaves. The cuticle and epidermis of N. retusa and A. halimus stems were unaffected by salinity. However, root anatomical parameters (root cross section area, cortex thickness and stele to root area ratio), and stem anatomical parameters (stem cross section area and cortex area) were promoted at 100–200 mM NaCl. Indicating that low to moderate salinity had a stimulating effect on root and stem growth of these xero-halophytic species. At higher salinities, root and stem structures were altered significantly, and their percentages of reduction were higher in A. halimus than in N. retusa whereas, in M. arborea, they were strongly altered as salinity rose. NaCl (100–300 mM) reduced leaf water content by 21.2–56.2% and specific leaf area by 51–88.1%, while increased leaf anatomical parameters in M. arborea (e.g. increased thickness of upper and lower epidermis, palisade and spongy mesophyll, entire lamina, and increased palisade to spongy mesophyll ratio). Similar results were evidenced in A. halimus leaves with salinity exceeding 100 mM NaCl. Leaves of N. retusa were thinner in salt-stressed plants while epidermis thickness and water content was unaffected by salinity. The size of xylem vessel was unchanged under salinity in the leaf’s main vein of the three species while we have increased number in M. arborea leaf main vein in the range of 200–300 mM NaCl. A longer distance between leaf vascular bundle, a reduced size and increased number of xylem vessel especially in stem than in root vascular system was evidenced in M. arborea treated plants and only at (400–800 mM) in the xero-halophytic species. The effects of NaCl toxicity on leaf, stem and root ultrastructure are discussed in relation to the degree of salt resistance of these three species. Our results suggest that both N. retusa and A. halimus show high tolerance to salinity while M. arborea was considered as a salt tolerant species.     

Critical thermal limits and their responses to acclimation in two sub-Antarctic spiders: <Emphasis Type="Italic">Myro kerguelenensis</Emphasis> and <Emphasis Type="Italic">Prinerigone vagans</Emphasis>

Despite the relative richness of spider species across the Southern Ocean islands remarkably little information is available on their biology. Here, the critical thermal limits of an indigenous (Myro kerguelenensis, Desidae) and an introduced (Prinerigone vagans, Linyphiidae) spider species from Marion Island were studied after 7–8 days acclimation to 0, 5, 10 and 15°C. Critical thermal minima (CT_Min) were low in these species by comparison with other spiders and insects measured to date, and ranged from −6 to −7°C in M. kerguelenensis and from −7 to −8°C in P. vagans. In contrast, critical thermal maxima (CT_Max) were similar to other insects on Marion Island (M. kerguelenensis: 35.0–35.6°C; P. vagans: 35.1–36.0°C), although significantly lower than those reported for other spider species in the literature. The magnitude of acclimation responses in CT_Max was lower than those in CT_Min for both species and this suggests decoupled responses to acclimation. Whilst not conclusive, the results raise several important considerations: that oxygen limitation of thermal tolerance needs to be more widely investigated in terrestrial species, that indigenous and alien species might differ in the nature and extent of their plasticity, and that upper and lower thermal tolerance limits might be decoupled in spiders as is the case in insects.