The retrolateral tibial apophysis in spiders—shaped by sexual selection?

The functional significance of the retrolateral tibial apophysis (rta) on the male pedipalps in four spider species with different mating positions is investigated with the help of histological serial sections prepared after freeze-fixing copulating pairs with liquid nitrogen. The results of this study, as well as most data in previous works, suggest that the rta is mostly used to fix the male pedipalp to the female epigyne in order to ensure the intromission of the sperm transferring embolus. This is in accordance with the female choice hypothesis on genitalia which predicts that species-specific genital structures should directly or indirectly contact the female during copulation and thus be shaped by sexual selection.     

One new species of the genus Belisana Thorell, 1898 (Araneae,Pholcidae) from northern Vietnam

One new species Belisana denticulata sp. n. (♂) is reported from northern Vietnam based on material collected by fogging the forest canopy. This species resembles Belisana scharffi Huber, 2005, but can be distinguished by relatively long distance between proximal parts of proximo-lateral apophysis and distal apophysis on male chelicerae, by presence of a nearly saddle-shaped prolateral sclerite on procursus, and by different shape of retrolateral membranous flap on procursus. Type specimens are deposited in the Vietnam Academy of Science and Technology in Hanoi.     

Copulatory mechanics in the wolf spider Agalenocosa pirity reveals a hidden diversity of locking systems in Lycosidae (Araneae)

Genital traits are among the fastest to evolve, and the processes that drive their evolution are intensively studied. Spiders are characterized by complex genitalia, but the functional role of the different structures during genital coupling is largely unknown. Members of one of the largest spider groups, the retrolateral tibial apophysis (RTA) clade, are characterized by a RTA on the male palp, which is thought to play a crucial role during genital coupling. However, the RTA was lost in several families including the species-rich wolf spiders (Lycosidae) leading to the hypothesis that the genital coupling is achieved by alternative mechanisms. Here, we investigate the genital interactions during copulation in the wolf spider Agalenocosa pirity (Zoicinae) on cryofixed mating pairs using electron, optical and X-ray microscopy and compare our findings with other lycosids and entelegyne spiders. We found an unprecedented coupling mechanism for lycosid spiders involving the palea and a membranous cuticle folding adjacent to the epigynal plate. Additionally, we show an uncommon coupling between the median apophysis and the contralateral genital opening, and confirmed that the terminal apophysis acts as functional conductor, as previously hypothesized for males of Zoicinae. Phylogenetic mapping of RTA indicated that the basal tibial process found in Agalenocosa is a secondary acquisition rather than a modified RTA.     

Molecular phylogeny of the tropical wandering spiders (Araneae,Ctenidae) and the evolution of eye conformation in the RTA clade

Tropical wandering spiders (Ctenidae) are a diverse group of cursorial predators with its greatest species richness in the tropics. Traditionally, Ctenidae are diagnosed based on the presence of eight eyes arranged in three rows (a 2–4–2 pattern). We present a molecular phylogeny of Ctenidae, including for the first time representatives of all of its subfamilies. The molecular phylogeny was inferred using five nuclear (histone H3, 28S, 18S, Actin and ITS-2) and four mitochondrial (NADH, COI, 12S and 16S) markers. The final matrix includes 259 terminals, 103 of which belong to Ctenidae and represent 28 of the current 49 described genera. We estimated divergence times by including fossils as calibration points and biogeographic events, and used the phylogenetic hypothesis obtained to reconstruct the evolution of the eye conformation in the retrolateral tibial apophysis (RTA) clade. Ctenidae and its main lineages originated during the Paleocene–Eocene and have diversified in the tropics since then. However, in some analyses Ctenidae was recovered as polyphyletic as the genus Ancylometes Bertkau, 1880 was placed as sister to Oxyopidae. Except for Acantheinae, in which the type genus Acantheis Thorell, 1891 is placed inside Cteninae, the four recognized subfamilies of Ctenidae are monophyletic in most analyses. The ancestral reconstruction of the ocular conformation in the retrolateral tibial apophysis clade suggests that the ocular pattern of Ctenidae has evolved convergently seven times and that it has originated from ocular conformations of two rows of four eyes (4–4) and the ocular pattern of lycosids (4–2–2). We also synonymize the monotypic genus Parabatinga Polotov & Brescovit, 2009 with Centroctenus Mello-Leitão, 1929. We discuss some of the putative morphological synapomorphies of the main ctenid lineages within the phylogenetic framework offered by the molecular phylogenetic results of the study.     

印度血桐与中平树基因组调查及SSR分子标记分析

印度血桐与中平树是大戟科血桐属植物,该属植物具有多种药用价值,被广泛应用于民间医学中许多疾病的治疗,这两种植物种子中含有的神经酸也引起了研究者的高度关注。为确定适合印度血桐与中平树的全基因组测序研究策略,该研究采用二代高通量测序技术,结合生物信息学的方法首次测定了印度血桐与中平树的基因组大小、杂合率、重复率等基因组信息并初步分析了两种材料的SSR序列特征。结果表明:(1)印度血桐与中平树的基因组大小分别为986.84和946.23 M。(2)印度血桐与中平树的杂合率分别为0.75%和0.65%,重复序列比例分别为73.02%和71.5%。(3)通过对2种材料基因组序列的SSR特征分析,在印度血桐中共鉴定了4 499 185个SSR,在中平树中共鉴定了4 969 098个SSR。该研究结果为印度血桐与中平树SSR分子标记的筛选、开发以及全基因组深度测序提供了理论指导。     

Assessment of rampant genitalic variation in the spider genus Homalonychus (Araneae, Homalonychidae)

Abstract. Animal genitalia are often complex and thought to vary little within species but differ between closely related species making them useful as primary characters in species diagnosis. Spiders are no exception, with nearly all of the 40,462 (at the time of this writing) described species differentiated by genitalic characteristics. However, in some cases, the genitalia of putative species are not uniform, but rather vary within species. When intraspecific variation overlaps interspecific variation, it can be difficult (if not impossible) to place a name on a specimen. The quantification of shape variation in genitalia has not often been attempted, probably because until recently it was not a methodologically and computationally simple process. In the two currently recognized species of the spider genus Homalonychus , genitalic variation is rampant in both male and female structures, with some parts of the genitalia (e.g., the retrolateral tibial apophysis) differing in each specimen examined. In this study, geometric morphometric analysis employing landmark data is used to quantify both intra- and interspecific variation in this genus. The large amount of variation is condensed into two or three groups depending on the structures examined, and these groups correspond to either the two species or to previously established mitochondrial DNA clades within one of the species. The results also show that analyses of female structures do not separate the groups as readily as the analyses of the male structures. The large amount of variation present in some structures is not correlated with geography or population genetic structure.     

雄性水狼蛛生殖球顶部的扫描电镜研究

本文对我国已知的十一种水狼蛛(蜘蛛目:狼蛛科)生殖球顶部用扫描电镜进行了研究。结果表明,水狼蛛属蜘蛛插入器细长,其后端位于顶突上一突起的凹槽内,顶突作为功能引导器保护着插入器,而无其他狼蛛属具有的次生真正引导器;顶突的形状和其上的突起、顶突与插入器的相互关系对于种的分类与鉴定,特别是对于近似种的区分有较大的参考价值,但仅根据插入器从顶部升起的位置来作为分新属的主要标准,笔者认为还值得商榷和进一步探讨。     

The phylogenetic placement of Psechridae within Entelegynae and the convergent origin of orb‐like spider webs

Evolutionary convergence of phenotypic traits provides evidence for their functional success. The origin of the orb web was a critical event in the diversification of spiders that facilitated a spectacular radiation of approximately 12 000 species and promoted the evolution of novel web types. How the orb web evolved from ancestral web types, and how many times orb‐like architectures evolved in spiders, has been debated for a long time. The little known spider genus Fecenia (Psechridae) constructs a web that resembles the archetypical orb web, but morphological data suggest that Psechridae (Psechrus + Fecenia) does not belong in Orbiculariae, the ‘true orb weavers’, but to the ‘retrolateral tibial apophysis (RTA) clade’ consisting mostly of wandering spiders, but also including spiders building less regular webs. Yet, the data are sparse and no molecular phylogenetic study has estimated Fecenia's exact position in the tree of life. Adding new data to sequences pulled from GenBank, we reconstruct a phylogeny of Entelegynae and phylogenetically test the monophyly and placement of Psechridae, and in doing so, the alternative hypotheses of monophyletic origin of the orb web and the pseudo‐orb versus their independent origins, a potentially spectacular case of behavioural convergence. We also discuss the implications of our results for Entelegynae systematics. Our results firmly place a monophyletic Psechridae within the RTA clade, phylogenetically distant from true orb weavers. The architectural similarities of the orb and the pseudo‐orb are therefore clearly convergent, as also suggested by detailed comparisons of these two web types, as well as the spiders' web‐building behaviours and ontogenetic development. The convergence of Fecenia webs with true orbs provides a remarkable opportunity to investigate how these complex sets of traits may have interacted during the evolution of the orb.     

Frequent Failure of Male Monopolization Strategies as a Cost of Female Choice in the Black Widow Spider Latrodectus tredecimguttatus

In many mating systems, males strive for securing paternity through monopolizing females. As male monopolization attempts often contradict female interests, this conflict may fuel an evolutionary arms race. In the widow spider genus Latrodectus, females are commonly polyandrous, whereas males are monogynous, hence restricted to mate with a single female, making paternity protection particularly important. Potential mating plugs (specialized embolus sclerites of male copulatory organs) have been discovered in the complex female genital tracts of several Latrodectus species. In this study, we investigated mating strategies in the Mediterranean black widow spider Latrodectus tredecimguttatus and tested the adaptive value of female attacks against male monopolization efforts. In a double mating experiment, we manipulated the number of insertions (=copulations) for first and second males to assess female behaviour and male embolus sclerite placement success. Our results indicate that first males′ embolus sclerites inside the females′ sperm stores physically block sclerites of subsequent males. While female attacks did not affect the deposition of potential mating plugs, they significantly reduced copulation duration. Irrespective of female aggression, male sclerite placement failure occurred frequently, but large males were more successful than smaller competitors. We suggest that the complex genital morphology in both sexes may have co‐evolved antagonistically and female morphology could serve to favour large males for fertilization.     

Redescription of Piguetiella denticulata (Annelida, Clitellata, Naididae) from Japan and the Russian Far East, with a description of the genital organs in the species

A naidid oligochaete, Piguetiella denticulata Liang and Xie (Invertebrates of Wuling Mountains area, Southwestern China, pp 383–394, 1997), is redescribed based on new material from Japan and the Russian Far East, and its generic position is verified by an examination of the reproductive organs. P. denticulata closely resembles P. michiganensis in lacking eyes and dorsal hair chaetae, but it is distinguished from the latter by having intermediate teeth on both its dorsal and ventral crotchets. In Japan, P. denticulata is widely distributed and often abundant in mountain streams with sandy and gravelly bottoms.     

Red- and yellow-footed tortoises, <Emphasis Type="Italic">Chelonoidis carbonaria</Emphasis> and <Emphasis Type="Italic">C. denticulata</Emphasis> (Reptilia: Testudines: Testudinidae), in South American savannahs and forests: do their phylogeographies reflect distinct habitats?

Using sequence data of the mitochondrial cytochrome b gene, we investigated phylogeographic differentiation of the Amazonian tortoise species Chelonoidis carbonaria and C. denticulata. While C. carbonaria is generally restricted to savannah habitats and adjacent forests, C. denticulata is associated with wet tropical and subtropical forests. Our study suggests a correlation between distinct habitat preferences and phylogeography of the two species. In Maximum Parsimony, Maximum Likelihood and Bayesian analyses, haplotypes of C. carbonaria cluster in several distinct clades reflecting the species’ patchy distribution in savannah habitats. By contrast, haplotypes of C. denticulata are only weakly differentiated; a finding also confirmed by parsimony network analysis. This suggests that the contiguous Amazonian rainforest allows gene flow between populations of the forest-dwelling C. denticulata throughout the range, but significantly impedes gene flow in C. carbonaria. The phylogeographic structure and extant distribution pattern of C. carbonaria is supportive of former Amazonian rainforest fragmentation, enabling the dispersal of savannah species. Based on fossil calibration, we dated divergence times for the C. carbonaria clades using a relaxed molecular clock, resulting in average estimates ranging from 4.0–2.2 mya. This implies that the onset of rainforest fragmentation could predate the Pleistocene considerably. Furthermore, our findings call for further research on geographic and taxonomic variation in C. carbonaria and for a reassessment of the conservation status of the distinct genetic units.     

On Chytridium braun,Diplochytridium N. G., and Canteria N. G. (Chytridiales)

Summary The operculate genus Chytridium Braun is emended and restricted to approximately 25 known species and several incompletely known members which lack an apophysis and develop much like species of Rhizophydium, insofar as the zoosporangium and absorbing or rhizoidal system are concerned, and form endobiotic or intramatrical resting spores. This interpretation corresponds fairly closely to Braun's diagnosis of the type species.A new genus, Diplochytridium, is established to segregate the former Chytridium species with an endobiotic or intramatrical apophysis or prosporangium and resting spores, which may develop sexually or asexually. Some of these species have a well-defined endo-exogenous alternation of growth and development in which the apophysis appears to function as a prosporangium. As interpreted here, Diplochytridium includes approximately 20 of the known species.Another new genus, Canteria, is created for a parasite of Mougeotia which Canter first described as a species of Phlyctidium but later found to develop endobiotic resting spores or zygospores by the fusion of conjugation tubes.     

Microtubules do not control orientation of secondary cell wall microfibril deposition inMicrasterias

Summary The influence of the microtubule disorganizing substances amiprophos-methyl (APM) and colchicine on secondary wall formation inMicrasterias denticulata was investigated by the freezeetch technique. The results reveal that neither microtubule inhibitor changes the pattern of microfibril deposition. The application of APM or colchicine also does not cause any structural alterations of the microfibrils or of the protoplasmic (Pf) and the exoplasmic (Ef) fracture face of the plasma membrane, thus indicating that microtubules are not involved in secondary wall formation inM. denticulata. However, since areas of the plasma membrane which collapsed upon freeze-etching are restricted to the Pf-face of cells treated with microtubule inhibitors, cortical microtubules may function as mechanical support during secondary wall formation. In the cortical cytoplasm filamentous structures are found in close spatial relationship and an almost parallel alignment to rosettes of the plasma membrane.     

Sound is involved in multimodal communication of Loxosceles intermedia Mello-Leitão, 1934 (Araneae; Sicariidae)

Signals of different modalities are involved during courtship of the brown spider Loxosceles intermedia. A spine on the pedipalp is rubbed against the grooves on the retrolateral region of the chelicerae producing stridulatory signals, which have a dominant frequency of the airborne component range around 770 Hz for females and around 170 Hz for males. These values are significantly lower for the substrate-borne component. The sound pressure level of stridulatory signals lies below 50 dB and the velocity values below 1 mm/s. The copulation frequency does not depend on the presence of pedipalps in females; however, in males the removal of pedipalps decreases the courtship frequency. During courtship, females vibrate their abdomens after being touched by the courting male, producing tremulatory signals with the dominant frequency below 100 Hz, sound pressure level below 60 dB and velocity below 3 mm/s. This vibration may function as a sign of the akinesia state since it precedes the introduction of the embolus. Cuticular compounds probably determine the recognition of the male by the female. Data from the present study corroborate the generalist nature of L. intermedia in which signals of different modalities are used during courtship.     

A non-sperm transferring genital trait under sexual selection: an experimental approach

Male genitalia are among the fastest evolving morphological characters, and at a general level sexual selection seems to be involved. But experimental determination of the functions of many remarkable genitalic elaborations is very rare. Here we present the first study to address experimentally the adaptive function of a male genital structure that is not involved in sperm transfer. Females of the orb-weaving spider Argiope bruennichi are sexually cannibalistic and polyandrous. The male increases his paternity by obstructing the female's insemination duct with a fragment of his complex genitalia (embolus tip). We manipulated males by detaching another species-specific structure, the median apophysis spur, and found that the spur promotes breakage of the embolus tip inside the female duct, but does not affect the probability and duration of copulation. These data are novel in that they suggest that a genitalic structure which does not transfer sperm nevertheless evolved in the context of sperm competition.     

Proposal and Phylogenetic Relationships of Lapsamita,a New Genus of Lapsiines,and Description of a New Species (Araneae,Salticidae)

Lapsamita maddisoni gen. et sp. nov. is described from Bahia, Brazil. The presence of palpal claws in females, long ventral spines on front tibiae and metatarsi and long retrolateral tibial apophyses in male palps suggested that the species was closely related to or even nested within Soesiladeepakius Makhan, 2007. To evaluate its phylogenetic position, a cladistic analysis was carried out using a data matrix comprising 24 morphological characters, scored for 13 taxa. The analysis showed L. maddisoni as the sister group of Soesiladeepakius, supporting the proposal of the new genus. Character evolution is discussed and compared to a previous study on the group.     

Effects of interactions between algae and grazing gastropods on the structure of a low-shore intertidal algal community

Summary At low levels on shores in New South Wales, foliose algae are abundant and often occupy all substrata; microalgal grazing gastropods are rare or absent. At higher levels, foliose algae are sparse or absent and grazing gastropods are abundant. Hypotheses for the causes of the lower vertical limits of distribution of these grazers include the effects of increased predation or the deleterious physiological effects of increased period of submergence at lower levels on the shore. Alternatively, the presence of the algae, because they occupy space and deprive the grazers of substratum for feeding, may prevent the downward movement, or survival of the grazers at low levels. Under the first two of these hypotheses, algae are able to colonize and grow in low-shore areas as an indirect result of factors which remove grazers. Under the third hypothesis, the algae are directly responsible for the lack of grazers.Experimental clearings of the low-shore algae and introductions of the mid-shore limpets Cellana tramoserica and Siphonaria denticulata were used to test these hypotheses. C. tramoserica grazes microalgae and removes them from the substratum, preventing colonization. S. denticulata, in contrust, crops the algae, leaving a visible cover of algae on the substratum, which can grow rapidly. Because of its method of feeding, S. denticulata had no measurable impact on the rates of colonization, nor on the dry weights of algae, compared with those of ungrazed areas. C. tramoserica could keep cleared areas tree from foliose algae, but only when the limpets were mainfained in great density (10 per 900 cm²). They were less effective where wave-action was greater.Neither species of limpets could survive when placed onto beds of mature algae, because they had no substratum on which to cling and were swept away by the waves. C. tramoserica did not invade clearings below their lower limit of distribution where they had to move over a bed of foliose algae. Few C. tramoserica moved directly downshore into cleared areas. When placed on bare rock within low-shore beds of algae of different ages, S. denticulata remained amongst the algae and maintained their tissue-weights. Few C. tramoserica remained in areas with well-developed algae, compared with areas having sparse algal growth. Those Cellana which remained amongst well-developed algae lost weight, whereas limpets in areas with less algal growth mammtained their weights. In experimental cages in low-shore beds of algae, where the limpets were inaccessible to potential predators, C. tramoserica lost weight and died. On cleared areas they survived for many weeks, but lost weight and died as algae grew and covered the substratum. In the absence of predation, the micro-algal grazer C. tramoserica could not survive in lowshore areas because algae grew too fast and occupied the substratum, making it inaccessible for the limpets to graze; the algae, once grown beyond small sporelings, are not a suitable food-source for C. tramoserica, and the loss of weight and death of these limpets is attributable to starvation.The lower limit of distribution of C. tramoserica is not due to the direct effects of physical factors associated with prolonged submersion, nor to the impact of predators, but is apparently determined by the presence of rapidly growing, extensive beds of foliose algae at low levels on the shore. The cause of the limit of distribution of S. denticulata is not yet known and predation may prove to be important. Removal of S. denticulata from low-shore algal beds would not, however, affect the domination of substrata by algae. Grazing by S. denticulata at very great density had no effect on algal cover nor weight. In the intertidal community studied, the persistence of a low-shore algal zone, bounded above by abundant grazers is not influenced by the activities of predators, but is a direct result of interactions between the grazers and the algae.     

The spores of Pteris cretica complex (Pteridaceae-Pteridophyta) in America

Spore morphology in the Pteris cretica complex, including Pteris brasiliensis, P. ciliaris, P. cretica, P. denticulata var. denticulata, P. denticulata var. tristicula, P. ensiformis, P. multifida and P. mutilata was examined using light and scanning electron microscope. The spores are trilete, triangular to circular in shape, with an equatorial thickening (= cingulum). Equatorial diameter ranges from 29 to 69 μm, and polar diameter from 18 to 53 μm. Exospore is proximally verrucate and distally rugate, with the exception of Pteris ensiformis, which has cones on both polar faces. Perispore is generally less than 1 μm thick, apparently single-layered in section, and translucent under light microscope. Spheroids were frequently observed on the surfaces of both perispore and exospore. Hyaline spores lacking cingulum were found in all specimens. Pteris brasiliensis, P. cretica and P. denticulata exhibit pronounced polymorphism and, in addition to trilete spores these taxa also produce atypical spores such as tetralete, monolete and intermediate types.     

Zelandoperla maungatuaensis sp. n. (Plecoptera: Gripopterygidae), a new flightless stonefly species from Otago,New Zealand

ABSTRACT

A new wing-reduced species of the stonefly genus Zelandoperla Tillyard is described from Otago, New Zealand. Zelandoperla maungatuaensis sp. n. differs from a related species, Z. denticulata, primarily by lacking full wing development. We used morphological, geographical, and genetic evidence to assess the proposed status of Z. maungatuaensis sp. n. and Z. denticulata as separate monomorphic species, as opposed to conspecific members of a polymorphic species. High genetic divergence was found between distinctly allopatric populations, supporting the status of Z. maungatuaensis sp. n. as a distinct monomorphic species.     

A New Species of Theridion Walckenaer (Araneae: Theridiidae) from Korea

A new species, Theridion longipili sp. nov. (Theridiidae), is described from Korea. It is easily distinguished from other congeners by the structure of conductor, radix, median apophysis, and the female epigynum and internal genitalia.