Contrasting patterns of hybridization in large house spiders (Tegenaria atrica group, Agelenidae)

The integrity of species is not fixed and may vary geographically. Here we investigate the geographic distributions and interactions of species in the Tegenaria atrica group (Araneae: Agelenidae). Detailed mapping of T. saeva and T. gigantea in England and Wales shows them to be broadly allopatric in southern England with a tightly defined, and possibly long-standing, narrow zone of parapatry in central southern England. In the north of England (Yorkshire), by contrast, the species are broadly sympatric as a result of recent range expansions. GIS techniques are used to map the species distributions and to quantify, we believe for the first time, the intimacy of interspecific interactions. The extent and nature of hybridization in these two areas is examined through regression and multivariate analyses of morphology. We show that the relative incidence of hybridization is much greater in Yorkshire than within the parapatric zone in the south. Clear patterns of asymmetric introgression are observed in both northern and southern England, with a greater impact of T. gigantea on T. saeva than vice versa. We find no sign of morphological reproductive character displacement at the zone of parapatry that might indicate reinforcement, although we cannot exclude more subtle effects, for example via cuticular pheromones. The integrity of these two species seems to be breaking down in northern England, a process that might gain momentum as the gene pools become more similar.     

Taxonomic revision of the genus Succisella (Dipsacaceae) in the Iberian Peninsula

A revision of the three endemic Iberian species of Succisella G. Beck ( S. carvalhoana , S. microcephala and S. andreae-molinae ), based on herbarium studies, SEM photographs and field observations, is presented utilizing morphological, palynological, karyological, biogeographical and ecological characters. The distribution of the species in the Iberian Peninsula is shown in a grid map. Full synonymy is given for all taxa.  © 2004 The Linnean Society of London, Botanical Journal of the Linnean Society , 2004, 144 , 351–364.     

A taxonomic revision of the Tragulus mouse-deer (Artiodactyla)

The taxonomy of South-East Asian mouse-deer ( Tragulus ) is complex, and after some 120 years of considerable taxonomic revisions of the genus a clear key is still lacking for the determination of species and subspecies. Through craniometrical analysis of 338 skulls of Tragulus and some study of coat coloration patterns we have come to a better understanding of mouse-deer taxonomy. Our results show that there are three species groups: the T. javanicus -group, the T. napu -group, and T. versicolor . Within the T. javanicus -group we recognize three species: T. javanicus (from Java), T. williamsoni (from northern Thailand and possibly southern China), and T. kanchil (from the rest of the range), and within these species we provisionally recognize 16 subspecies. Within the T. napu -group we recognize two species: T. nigricans (from Balabac), and T. napu (from the rest of the range); within these species we provisionally recognize eight subspecies. T. versicolor from Nhatrang, south-east Vietnam, is distinct from the two previous groups; it is, however, unclear whether this species is still extant.  © 2004 The Linnean Society of London, Zoological Journal of the Linnean Society , 2004, 140 , 63–102.     

Taxonomic position of and generic distinction between Parepactophanes Kunz, 1935 and Taurocletodes Kunz, 1975 (Copepoda, Canthocamptidae incertae sedis), with description of a new species from the Black Sea

Both sexes of a new species of Taurocletodes Kunz, 1975 (Copepoda, Harpacticoida, Canthocamptidae incertae sedis ) are described from sandy beaches along the Black Sea coast of Turkey. The genus Taurocletodes is removed from its synonymy with Parepactophanes Kunz, 1935 and re-instated as a valid genus, accommodating the type species T. dubius (Noodt, 1958) comb. nov. and T. tumenae sp. nov. Both genera can be differentiated by major differences in the segmentation of P1–P3 endopods, the absence/presence of penicillate setae on P1 endopod, the number of outer spines on P2–P4 exp-3, the armature of P2–P4 endopods and the sexual dimorphism of P2 endopod and P3 exopod. T. tumenae sp. nov. and T. dubius are morphologically very similar, differing in morphometric characters related to the endopodal segmentation of P1 and P4, and armature of the male P5. The controversial taxonomic status of Parepactophanes and Taurocletodes within the family Canthocamptidae is discussed.  © 2004 The Linnean Society of London, Zoological Journal of the Linnean Society , 2004, 140 , 469−486.     

Molecular variation and speciation in Antitrichia curtipendula s.l. (Leucodontaceae, Bryophyta)

Molecular variation in Antitrichia curtipendula (Hedw.) Brid. s.l. was studied based on the nuclear internal transcribed spacer (ITS) and the chloroplast markers trn L- trn F and rpl 16, and analysed by neighbour joining (for ITS; recombination present), maximum parsimony (chloroplast markers) and TCS (haplotype network). Old World plus E North American populations belong to a different lineage than those of W North America. These are molecularly well differentiated and are treated as A. curtipendula and A. gigantea (Sull. & Lesq.) Kindb. Two distinct groups of Old World haplotypes are separated by one 'missing' haplotype and are interpreted as cryptic species. Tropical African populations share one ITS deletion and form a lineage within one of the cryptic species. Molecular variation within A. gigantea , within each of the two cryptic Old World plus E North American (except tropical African) haplotype groups, and among tropical African populations are of similar magnitude, suggesting that analogous mechanisms and similar time spans explain the found variation. Events related to Pleistocene climatic oscillations are suggested as having caused this differentiation within each group, whereas the African lineage was probably split off before this. Identical tRNA-Gly sequences were found in 33 specimens; new primers were designed for rpl 16 and ITS 1+2.  © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society , 2008, 156 , 341–354.     

Reversible frequency-dependent predation of a puffer, Takifugu niphobles (Pisces: Tetraodontidae), related to spatial distribution of colour-polymorphic prey

The puffer Takifugu niphobles is a top predator of hard-shelled prey such as molluscs; its predatory tactics may affect the evolution of prey coloration. Two hypotheses concerning its foraging were tested: (1) T. niphobles shows frequency dependence in foraging colour-polymorphic prey, and (2) such dependence reverses in response to changes in prey distribution. Captive fish were provided with 70 artificial prey, coloured either dark brown or pale brown, at four frequencies (1 : 4, 2 : 3, 3 : 2, 4 : 1) and in two distribution patterns (uniform and aggregated). When prey were uniformly distributed, frequency and feeding rate significantly influenced colour preference: the common morph was consumed more. When prey were aggregated, frequency significantly affected preference only when the feeding rate was low, in which case the rare morph was consumed more. Thus both hypotheses were supported. The impact of T. niphobles 's frequency-dependent predation and its reversal on the colour evolution of prey species, especially molluscs, is discussed.  © 2004 The Linnean Society of London, Biological Journal of the Linnean Society , 2004, 81 , 197–202.     

Revision of Trigonostomum Schmidt, 1852 (Platyhelminthes, Typhloplanoida, Trigonostomidae) with the description of seven new species

A morphological and taxonomic account of the genus Trigonostomum is provided. All known species are discussed and briefly re-described where necessary. Seven new species are described: T. franki from Curaçao, Florida (USA), the East African Coast and New Caledonia, T. nataschae from the French sub-Antarctic island Kerguelen, T. spinigerum from New Caledonia and T. watsoni from the Australian East Coast and New Caledonia. T. tori and T. galapagoensis , both formerly enclosed in T. setigerum , are considered new species, while T. australis also belongs to the same species group. Proxenetes denhartogi is transferred to Trigonostomum . Based on a comparison of old and new material, T. marki is synonymized with T. penicillatum , while T. prytherchi and T. divae are regarded as junior synonyms of T. lilliei ; T. intermedium and T. quadrifolium are considered synonyms of T. coronatum . Three species are considered species inquirendae : T. brunchorsti , T. piriforme and Marinellia lingulifera . Similarities and differences of the 17 valid species are discussed and summarized in an identification key.  © 2004 The Linnean Society of London, Zoological Journal of the Linnean Society , 2004, 141 , 271–296.     

Evolutionary significance of oral morphology in the carnivorous tadpoles of tiger frogs, genus Hoplobatrachus (Ranidae)

We describe the larval stages of three species of the Asian-African tiger frogs Hoplobatrachus chinensis, H. occipitalis and H. tigerinus . The tadpoles of all three species are very similar, with peculiar oral features: (1) double rows of needle-like labial teeth, (2) strong emarginations on the large jaw sheaths and (3) keratinized spurs on the buccal floor. Characters 1 and 2 (and perhaps 3) are probably related to the carnivorous habits of these tadpoles. A molecular phylogeny based on 2430 base pairs of two nuclear and four mitochondrial genes corroborated monophyly of Asian and African Hoplobatrachus, and identified Euphlyctis as their sister group. Tadpoles of the latter genus lack buccal spurs and double labial tooth rows but share large jaw sheaths, the upper with a medial projection. Therefore, the common ancestor of Euphlyctis and Hoplobatrachus probably was also characterized by this state, and may have been facultatively carnivorous. Further carnivorous specializations in Hoplobatrachus could explain why tiger frogs have been so successful in populating arid environments where ponds are at high risk of desiccation. Larval morphology may prove to be the key innovation which enabled them to disperse, in the Late Cenozoic, into their current very wide distribution area in Asia and Africa.  © 2004 The Linnean Society of London, Biological Journal of the Linnean Society , 2004, 81 , 171–181.     

Phylogenetic relationships of thorny catfishes (Siluriformes: Doradidae) inferred from molecular and morphological data

Doradidae is a putatively monophyletic group of South American freshwater catfishes containing 30 extant genera and 72 valid species. Only one study to date has attempted to estimate phylogenetic relationships among doradids. This morphological analysis partitioned species into two basal genera ( Wertheimeria and Francisodoras ) and a crown group of three subfamilies (Platydoradinae, Astrodoradinae and Doradinae) whose relationships were unresolved. No subsequent work has been done to resolve the subfamilial trichotomy or to assess whether postulated intergeneric relationships are accurate. We address this problem with complete sequences (2.5 kilobases, kb) of mitochondrial 12S and 16S rRNA genes and partial (1.3 kb) sequences of the nuclear elongation factor-1 alpha (EF1α) gene from representatives of 23 doradid genera (43 species) and 13 outgroups from additional siluriform families. Phylogenetic analysis of these data yields strong support for the monophyly of Doradidae and Astrodoradinae (as well as other relationships), but otherwise shows significant conflict with morphological results. A partial re-examination of published morphological data indicates that many characters may have been incorrectly polarized and many taxa have incorrect state assignments. Our results provide a framework for ongoing efforts to describe the species-level diversity of this poorly understood neotropical family.  © 2004 The Linnean Society of London, Zoological Journal of the Linnean Society , 2004, 140 , 551–575.     

A new species of Clivia (Amaryllidaceae) endemic to the Pondoland Centre of Endemism, South Africa

Clivia robusta B.G. Murray, Ran, de Lange, Hammett, Truter et Swanevelder sp. nov. (Amaryllidaceae) is a tubular, pendulous-flowered Clivia species, restricted to the Pondoland Centre of Endemism, South Africa. The unique morphology, distribution, karyotype and molecular fingerprint distinguish it from all other pendulous-flowered species in the genus.  © 2004 The Linnean Society of London, Botanical Journal of the Linnean Society , 2004, 146 , 369–374.     

Maximizing information in systematic revisions: a combined molecular and morphological analysis of a cryptic green pitviper complex (Trimeresurus stejnegeri)

Although the integration of DNA information in taxonomy has been invaluable, logistical problems relating to sampling can seriously limit its applicability. Here we describe the analysis of a morphologically cryptic species complex, in which we maximize the information present by using both a DNA phylogeny and a multivariate morphometric approach. The green pitviper Trimeresurus stejnegeri s.l. is widespread in Asia, with a number of described subspecies (some of which are considered full species by some workers) and two new species that have recently been described from Thailand. The phylogeny indicates three clades, which can also be discerned in the principal component analyses of morphological variation. Combining molecular and morphological information permits evaluation of the taxonomic position of populations not represented in the phylogeny − in particular, the subspecies T. s. chenbihui and T. s. yunnanensis . We discuss nomenclatural issues raised by this analysis, although these cannot be fully resolved until the holotypes of these subspecies can be examined. Finally, we apply a molecular clock calibrated in New World pitvipers, and discuss some of the palaeoclimatic changes that might have impacted upon diversification in this group.  © 2004 The Linnean Society of London, Biological Journal of the Linnean Society, 2004, 82 , 219–235.     

Cranial function in a late Miocene Dinocrocuta gigantea (Mammalia: Carnivora) revealed by comparative finite element analysis

Carnivoran ecomorphologies evolved repeatedly during the Cenozoic. Whereas extreme forms (e.g. sabretoothed predators) probably represent similarities in ecology, other morphologies are more subtle with respect to the extent of their shared niche space. Finite element models of the skulls of Dinocrocuta gigantea , Canis lupus , and Crocuta crocuta were constructed to test the interpretation of D. gigantea as a bone cracker, an interpretation made on the basis of its large, conical premolars, and robust cranial morphology. Dinocrocuta gigantea is also of interest because it represents a lineage that has been placed in its own family, sister to Hyaenidae. Thus, functional similarity in craniodental performance could represent rapid convergence. The findings obtained indicate that the crania of D. gigantea and C. crocuta perform better in stress dissipation and distribution than that of C. lupus , regardless of P3 or P4 biting. In particular, the domed frontal region of the bone crackers received lower and more evenly distributed stress than C. lupus . Thus, the craniodental forms of the two bone-crackers are linked by functional advantage over that of C. lupus . Further examination of lineages such as borophagine canids could elucidate the extent of functional convergence of the bone-cracking ecomorph across diverse groups.  © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 96 , 51–67.     

Two new species of Sicyos (Cucurbitaceae) from Guerrero and Oaxaca, Mexico

Two new species of Sicyos from Mexico are described and illustrated: Sicyos cordifolius from the state of Guerrero, which belongs to the group with dry, armed fruits, and Sicyos bulbosus from the state of Oaxaca, which belongs to the group with fleshy, unarmed fruits. Sicyos cordifolius is quite different from the rest of the species previously described. Although S. bulbosus is very similar to S. galeottii Cogn., it is clearly different in receptacle shape and size.  © 2004 The Linnean Society of London, Botanical Journal of the Linnean Society , 2004, 145 , 373–378.     

Phototaxis and the evolution of isogamy and 'slight anisogamy' in marine green algae: insights from laboratory observations and numerical experiments

The evolution of anisogamy in marine algae was studied through numerical simulations of gamete mating behaviour in three dimensions, using observed traits of marine green algae as input parameters. The importance of phototaxis became apparent from the numerical experiments: all gametes with phototactic systems are favoured over those without, but this advantage is reduced with increasing tank depth or shorter search times. Phototactic gametes were advantaged over non-phototactic gametes if the water was shallower than about 30–40 mm when the time available for gamete encounter was 1000 time steps (5.55 min). If gametes of both sexes are positively phototactic, slightly anisogamous species are at a disadvantage to isogamous species, which invalidates the sperm-limitation theory as a driver for the evolution of slight anisogamy. Conflicting selection forces of search efficiency and zygote fitness may be needed.  © 2004 The Linnean Society of London, Botanical Journal of the Linnean Society , 2004, 144 , 321–327.     

Karyomorphology of Incarvillea (Bignoniaceae) and its implications in distribution and taxonomy

The karyomorphology of 11 species of the genus Incarvillea Juss. is reported. The chromosome numbers of all species studied are 2 n  = 22. The interphase nuclei and prophase chromosomes were found to be of the simple chromocentre type and the interstitial type, respectively. The asymmetry of the karyotype of I. arguta (two populations) in subgenus Amphicome is type 2A. The karyotypes of Incarvillea s inensis var. sinensis , I.  s inensis var. przewalskii, and I. olgae in subgenus Incarvillea are of asymmetry type 3A. The remaining nine species and one variety in subgenus Pteroscleris are also of asymmetry 3A. Data on three species and one variety studied are first reports. This study indicates that karyotype variation at the diploid level appears to be the predominant feature of chromosome evolution in the genus Incarvillea . According to this study of karyomorphology, morphological characteristics and geographical distribution, it seems that the three subgenera should be regarded as three independent genera. The geography of the genus is discussed.  © 2004 The Linnean Society of London, Botanical Journal of the Linnean Society , 2004, 144 , 113–121.     

Molecular differentiation between coexisting species of Taraxacum sect. Erythrosperma (Asteraceae) from populations in south-east and west Germany

The present study focuses on the genetic differentiation between six coexisting species of Taraxacum sect. Erythrosperma . Twenty-six individuals of T. rubicundum , T. brachyglossum , T. tortilobum , T. lacistophyllum , T. parnassicum and T. scanicum were sampled at 14 locations in south-east (Bavaria) and west Germany (Eifel). Using random amplified polymorphic DNA (RAPD) analysis 139 fragments were amplified. Nineteen of these were found to be species specific. The level of polymorphic bands within the different Taraxacum species varied between 0% and 15.8%. An analysis of molecular variance (AMOVA) revealed strong differentiation between the investigated species: 14.3% of the molecular variance were found within the species, while 85.7% of the genetic variability was observed between the species. However, a geographical differentiation between the different regions could not be observed. All analysed species were clearly separated from each other in a cluster analysis using the neighbour joining technique. The observed strong genetic differentiation between the Taraxacum species clearly supports the agamospecies concept of Taraxacum sect. Erythrosperma , which is at present mainly based on morphological and cytological criteria  © 2004 The Linnean Society of London, Botanical Journal of the Linnean Society , 2004, 145 , 109–117.     

Three new species with two flowered spikelets in Acantholimon (Plumbaginaceae) from East Anatolia, Turkey

Three new species, Acantholimon bashkaleicum sp. nov. , Acantholimon artosense sp. nov. and Acantholimon hoshapicum sp. nov. (Plumbaginaceae) are described and illustrated. The species are all confined to B9/B10 Van Province in East Anatolia where they grow either on calcareous mountain slopes or on mountain steppes. Diagnostic morphological characteristics from the closely related species are given, along with a discussion dealing with their taxonomic relationships, and their conservation statuses are pointed out. A revised key to the Acantholimon species with heterophyllous leaves, two or more flowered and four or more bracteated spikelets is also provided.  © 2004 The Linnean Society of London, Botanical Journal of the Linnean Society , 2004, 144 , 497–505.