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Phasmarhabditis quinamensis sp. n. (Nematoda: Rhabditidae) from tropical terrestrial gastropods in southern Vietnam
Abstract
Phasmarhabditis quinamensis sp. n. was recovered from several tropical terrestrial gastropod species collected in Cat Tien National Park in southern Vietnam with the snail, Sesara sp., designated as the type host. Phasmarhabditis quinamensis sp. n. is recognised by males and females with a lip region set off by the circle of six triangular low probolae, three bilobed, separated lips, stoma nearly as wide as long, the first genital papilla in males not incorporated into the bursa, the ensheathed dauer juveniles more than 1 mm long and with two circles of papillae at the head end and prominent amphidial apertures, a long filamentous tail and, when exsheathed, with a short, conical tail ending with two tiny spikes. The head structure of P. quinamensis sp. n. differentiates it from all nominal species of Phasmarhabditis. Phasmarhabditis quinamensis sp. n. is the second species of the genus found in Cat Tien National Park. The sympatric species P. meridionalis was also found during the present study. Phylogenetically, both species belong to different lineages within Phasmarhabditis . The molecular analysis based on partial sequences of LSU rDNA, and ITS rDNA regions showed P. kenyaensis to be the closest species to P. quinamensis sp. n.
... In P. thesamica [55], GP1 and GP2 are considerably further apart than are GP2 and GP3, whereas these distances are similar in most individuals of P. pelhami n. sp. and P. pellio. In P. quinamensis [46], each of the three pairs of lips are strongly fused and separated from the other pairs, different from our strains where there is distinct separation between lips of each pair. Four species, P. apuliae, P. bohemica, P. circassica, and P. clausiliiae [6,16,45], all have a similar GP formula and can only be distinguished by DNA sequences and morphometrics. ...
... Pellioditis bohemica (Nermuť, Půža, Mekete & Mráček, 2017)-near Chelčice, CzechRepublic; from Deroceras reticulatum from a red currant plantation; also from soil samples baited with Galleria larvae[6]. P. quinamensis(Ivanova & Spiridonov, 2022)-Cát Tiên National Park, southern Vietnam; from the land snail Sesara sp. Further isolates from seven additional genus taxa of terrestrial snails in that National Park[46]. ...
... P. quinamensis(Ivanova & Spiridonov, 2022)-Cát Tiên National Park, southern Vietnam; from the land snail Sesara sp. Further isolates from seven additional genus taxa of terrestrial snails in that National Park[46]. ...
Recently, much attention has been focused on a group of rhabditid nematodes called Phasmarhabditis , a junior synonym of Pellioditis , as a promising source of biocontrol agents for invasive slugs. Pellioditis pelhami n. sp. was first isolated from earthworms near Pelham Bay Park in Bronx, New York, USA, in 1990 and has been found to be pathogenic to slugs as well as some earthworms. It has also been used in several comparative developmental studies. Here, we provide a description of this species, as well as a redescription of a similar earthworm-associated nematode, Pellioditis pellio Schneider, 1866, re-isolated from the type locality. Although P. pelhami n. sp. and P. pellio are morphologically similar, they are reproductively isolated. Molecular phylogenetic analysis places both species in a clade that includes all species previously described as Phasmarhabditis which are associated with gastropods. Phasmarhabditis Andrássy, 1976 is therefore a junior synonym of Pellioditis Dougherty, 1953. Also, P. bohemica Nermut’, Půža, Mekete & Mráček, 2017, described to be a facultative parasite of slugs, is found to be a junior synonym of Pellioditis pellio (Schneider, 1866), adding to evidence that P. pellio is associated with both slugs and earthworms. The earthworm-associated species P. pelhami n. sp. and P. pellio represent different subclades within Pellioditis , suggesting that Pellioditis species in general have a broader host range than just slugs. Because of this, caution is warranted in using these species as biological control agents until more is understood about their ecology.
... Phasmarhabditis hermaphrodita has been shown to provide significant protection against slug damage when applied to a range of crops including lettuce, wheat and Chinese cabbage (see Rae et al., 2007). Phasmarhabditis hermaphrodita has been used to control slugs across northern Europe for over 25 years, yet there is little knowledge about the biology and worldwide distribution of other members of the genus Phasmarhabditis including: P. apuliae, P. papillosa, P. neopapillosa, P. valida, P. nidrosiensis, P. californica, P. tawfiki, P. bonaquaense, P. bohemica, P. huizhouensis, P. circassica, P. clausiliiae, P. quinamensis, P. meridionalis, P. kenyaensis and P. zhejiangensis (Andrássy, 1983;Hooper et al., 1999;Azzam, 2003;Tandingan De Ley et al., 2014Huang et al., 2015;Nermut' et al., 2016a, b, c;Ivanova et al., 2017Ivanova et al., , 2020Pieterse et al., 2020;Zhang & Liu, 2020;Ivanova & Spiridonov, 2021). An understanding of the biology, behaviour, distribution and diversity of these nematodes has the potential to develop new biological control agents based on the information gleaned from decades of research on P. hermaphrodita (see Rae et al., 2007 for further information). ...
... Phasmarhabditis species have been isolated from terrestrial gastropods from around the world including France (Maupas, 1900;Coupland, 1995), Egypt (Azzam, 2003;Genena et al., 2011), Norway (Ross et al., 2015), Chile (France & Gerding, 2000), New Zealand , South Africa (Ross et al., 2012;Pieterse et al., 2017), China (Huang et al., 2015;Zhang and Liu, 2020), Italy (Nermut' et al., 2016a), Czech Republic (Ner- mut ' et al., 2010, 2016b, c), the USA (Tandingan De Ley et al., 2016), Russia, Vietnam (Ivanova & Spiridonov, 2017, 2021Ivanova et al., 2021), Switzerland (Jaffuel et al., 2019), Germany (Schneider, 1859;Mengert, 1953), England (Wilson et al., 1993), Ireland (Carnaghi et al., 2017) and Wales (Andrus & Rae, 2019). However, only P. hermaphrodita, P. neopapillosa and P. papillosa have been isolated in Germany (Schneider, 1859;Mengert, 1953), and this is the first time P. californica has been isolated and identified from several locations in Germany. ...
... Phasmarhabditis species have been isolated from terrestrial gastropods from around the world including France (Maupas, 1900;Coupland, 1995), Egypt (Azzam, 2003;Genena et al., 2011), Norway (Ross et al., 2015), Chile (France & Gerding, 2000), New Zealand , South Africa (Ross et al., 2012;Pieterse et al., 2017), China (Huang et al., 2015;Zhang and Liu, 2020), Italy (Nermut' et al., 2016a), Czech Republic (Ner- mut ' et al., 2010, 2016b, c), the USA (Tandingan De Ley et al., 2016), Russia, Vietnam (Ivanova & Spiridonov, 2017, 2021Ivanova et al., 2021), Switzerland (Jaffuel et al., 2019), Germany (Schneider, 1859;Mengert, 1953), England (Wilson et al., 1993), Ireland (Carnaghi et al., 2017) and Wales (Andrus & Rae, 2019). However, only P. hermaphrodita, P. neopapillosa and P. papillosa have been isolated in Germany (Schneider, 1859;Mengert, 1953), and this is the first time P. californica has been isolated and identified from several locations in Germany. ...
... Notable families used in pest management are Heterorhabditidae and Steinernematidae [18]. The genus Phasmarhabditis Andrassy includes species that target pest gastropods [19], with 16 known species globally [20], while Oscheius, part of the Rhabditidae family, consists of free-living nematodes that feed on bacteria [21]. ...
This study of underground multitrophic communication, involving plant roots, insects, and parasitic nematodes, is an emerging field with significant implications for understanding plant–insect–nematode interactions. Our research investigated the impact of wireworm (Agriotes lineatus L. [Coleoptera: Elateridae]) infestations on the ascorbate–glutathione system in sweet pepper (Capsicum annuum L.) plants in order to study the potential role in root-exudate-mediated nematode chemotaxis. We observed that an A. lineatus infestation led to a decrease in leaf ascorbate levels and an increase in root ascorbate, with corresponding increases in the glutathione content in both roots and leaves. Additionally, a pigment analysis revealed increased carotenoid and chlorophyll levels and a shift towards a de-epoxidized state in the xanthophyll cycle. These changes suggest an individual and integrated regulatory function of photosynthetic pigments accompanied with redox modifications of the ascorbate–glutathione system that enhance plant defense. We also noted changes in the root volatile organic compound (VOC). Limonene, methyl salicylate, and benzyl salicylate decreased, whereas hexanal, neoisopulegol, nonanal, phenylethyl alcohol, m-di-tert-butylbenzene, and trans-β-ionone increased in the roots of attacked plants compared to the control group. Most notably, the VOC hexanal and amino acid exudate cysteine were tested for the chemotaxis assay. Nematode responses to chemoattractants were found to be species-specific, influenced by environmental conditions such as temperature. This study highlights the complexity of nematode chemotaxis and suggests that VOC-based biological control strategies must consider nematode foraging strategies and environmental factors. Future research should further explore these dynamics to optimize nematode management in agricultural systems.
... In P. thesamica [56], GP1 and GP2 are considerably further apart than are GP2 and GP3, whereas these distances are similar in most individuals of P. pelhamensis n. sp. and P. pellio. In P. quinamensis [47], each of the three pairs of lips are strongly fused and separated from the other pairs, different from our strains where there is distinct separation between lips of each pair. Although P. villasmundi is morphologically similar to P. pelhamensis in many ways (including a short buccal tube), there is greater space between GP1 and GP2 than between GP2 and GP3 (GP1-3 are similarly spaced in P. pelhamensis and P. pellio), and they differ substantially at the molecular level (26, 24 and 3.3% different at ITS1, ITS2 and LSU, respectively). ...
Recently, much attention has been focused on a group of rhabditid nematodes called Phasmarhabditis, a junior synonym of Pellioditis, as a promising source of biocontrol agents for invasive slugs. Pellioditis pelhamensis n. sp. was first isolated from earthworms near Pelham Bay Park in Bronx, New York, USA, in 1990 and has been found to be pathogenic to slugs as well as some earthworms. It has also been used in several comparative developmental studies. Here, we provide a description of this species, as well as a redescription of a similar earthworm-associated nematode, Pellioditis pellio Schneider, 1866, re-isolated from the type locality. Although P. pelhamensis n. sp. and P. pellio are morphologically similar, they are reproductively isolated. Molecular phylogenetic analysis places both species in a clade that includes all species previously described as Phasmarhabditis which are associated with gastropods. Phasmarhabditis Andrássy, 1976 is therefore a junior synonym of Pellioditis Dougherty, 1953. Also, Pellioditis bohemica Nermut’, Půža, Mekete & Mráček, 2017, described to be a facultative parasite of slugs, is found to be a junior synonym of Pellioditis pellio (Schneider, 1866), adding to evidence that P. pellio is associated with both slugs and earthworms. The earthworm-associated species P. pelhamensis n. sp. and P. pellio represent different subclades within Pellioditis, suggesting that Pellioditis species in general have a broader host range than just slugs. Because of this, caution is warranted in using these species as biological control agents until more is understood about their ecology.
... huizhouensis) from rotting leaf litter. [78][79][80][81][82][83][84][85][86][87][88][89][90][91] There were another two Phasmarhabditis species including P. nidrosienses (isolated from a marine habitat) and P. valida (isolated from littoral detritus), 92 but after revision they were moved to the genus Buetschlinema. 93 It is clear from the numerous surveys carried out over the last 30 years that Phasmarhabditis nematodes are commonly found in many countries from diverse terrestrial gastropod hosts. ...
Several slug species are highly pestiferous and threaten global sustainable agriculture. Current control methods rely heavily on metaldehyde pellets, which are often ineffective, harm nontarget organisms and have been banned in some countries. A viable alternative is the parasitic nematode Phasmarhabditis hermaphrodita (and recently P. californica), which has been formulated into a biological control agent (Nemaslug®) to control slugs across northern Europe. Nematodes are mixed with water and applied to soil where they seek out slugs, penetrate behind the mantle and kill them in 4–21 days. Phasmarhabditis hermaphrodita has been on the market since 1994 and since then there has been ample research on its use. Here we review the research carried out on P. hermaphrodita over the last 30 years since its development and release as a commercial product. We provide information on life cycle, worldwide distribution, history of commercialisation, gastropod immunity, host range, ecological and environmental factors that affect its success in the field, bacterial relationships, and summarise results of field trials. Finally, we suggest future directions for P. hermaphrodita research (and other Phasmarhabditis species) to enhance its use as a biological control agent to control slugs for the next 30 years. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.
... The genus Phasmarhabditis includes several nematode species that are potential biological control agents for pest gastropods [27]. Currently, there are 16 nominal species of Phasmarhabditis worldwide [28], and all tested species have been shown to specifically target and kill gastropods, providing protection to various crops [29]. The genus Oscheius, which belongs to the Rhabditidae family [30], contains free-living nematodes that feed on bacteria. ...
The effect of wireworm-damaged lettuce roots on the antioxidative defense system (ascorbate–glutathione cycle, photosynthetic pigments) and movement of insect/slug parasitic nematodes towards determined root exudates was studied in a glasshouse experiment. Lettuce seedlings were grown in a substrate soil in the absence/presence of wireworms (Elateridae). The ascorbate–glutathione system and photosynthetic pigments were analyzed by HPLC, while volatile organic compounds (VOC) emitted by lettuce roots were investigated by GC-MS. Herbivore-induced root compounds, namely 2,4-nonadienal, glutathione, and ascorbic acid, were selected for a chemotaxis assay with nematodes Steinernema feltiae, S. carpocapsae, Heterorhabditis bacteriophora, Phasmarhabditis papillosa, and Oscheius myriophilus. Root pests had a negative effect on the content of photosynthetic pigments in the leaves of infested plants, indicating that they reacted to the presence of reactive oxygen species (ROS). Using lettuce as a model plant, we recognized the ascorbate–glutathione system as a redox hub in defense response against wireworms and analyzed its role in root-exudate-mediated chemotaxis of nematodes. Infected plants also demonstrated increased levels of volatile 2,4-nonadienal. Entomopathogenic nematodes (EPNs, S. feltiae, S. carpocapsae, and H. bacteriophora) proved to be more mobile than parasitic nematodes O. myriophilus and P. papillosa towards chemotaxis compounds. Among them, 2,4-nonadienal repelled all tested nematodes. Most exudates that are involved in belowground tritrophic interactions remain unknown, but an increasing effort is being made in this field of research. Understanding more of these complex interactions would not only allow a better understanding of the rhizosphere but could also offer ecologically sound alternatives in the pest management of agricultural systems.
... The most well-known is a facultative parasite of slugs, Phasmarhabditis (Family Rhabditidae), a genus of bacterial-feeding soil-dwelling nematodes (Wilson & Grewal 2005). Phasmarhabditis currently contains eighteen nominal species (Ivanova et al. 2022;Rae et al. 2023), four of which have been shown to be pathogenic to slugs (Holley 2020;Ivanova & Spiridonov 2021;Schurkman et al. 2022a;Wilson & Grewal 2005): P. hermaphrodita (Schneider, 1859); P. papillosa, (Schneider 1866), Andrássy, 1983P. neopapillosa, (Mengert in Osche, 1954), Andrássy 1983and P. californica, (Tandingan De Ley et al., 2016). ...
Some slug species are considered a nuisance in agriculture and horticulture worldwide, causing economic losses to growers. Phasmarhabditis is a genus of bacteria-feeding nematodes that can parasitize slugs and snails and thus potentially serve as a biological control agent. Canada had no record of Phasmarhabditis until a survey conducted in 2019 reported a Canadian strain of Phasmarhabditis californica from a single Arion rufus slug. To build on this discovery, we surveyed three major agricultural sites, ten greenhouses, and nurseries in Alberta from June to September 2021 to collect pest slug species and investigate their associated nematodes, specifically P. californica. Slugs were collected from the field and returned to the laboratory to check for emerging nematodes on White traps. We collected 1331 slugs belonging to nine species, with Deroceras reticulatum being the most common. Only 45 (3.38%) slug samples were positive for nematodes, and the majority were identified to species level: Alloionema appendiculatum, Caenorhabditis briggsae, Caenorhabditis elegans, Panagrolaimus subelongatus, and Mesorhabditis spiculigera. We did not isolate P. californica from any of the slugs collected from these survey sites, which included the original site where P. californica was discovered. However, four D. reticulatum slugs retrieved from a residential garden sample were infected with P. californica. These findings suggest the possibility of a fragmented distribution of P. californica across Alberta. Future research should focus on extensively surveying agriculture and horticulture sites and residential gardens in different provinces across Canada.
... The most well-known is a facultative parasite of slugs, Phasmarhabditis (Family Rhabditidae), a genus of bacterial-feeding soil-dwelling nematodes (Wilson & Grewal 2005). Phasmarhabditis currently contains eighteen nominal species (Ivanova et al. 2022;Rae et al. 2023), four of which have been shown to be pathogenic to slugs (Holley 2020;Ivanova & Spiridonov 2021;Schurkman et al. 2022a;Wilson & Grewal 2005): P. hermaphrodita (Schneider, 1859); P. papillosa, (Schneider 1866), Andrássy, 1983P. neopapillosa, (Mengert in Osche, 1954), Andrássy 1983and P. californica, (Tandingan De Ley et al., 2016). ...
Some slug species are considered a nuisance in agriculture and horticulture worldwide, causing economic losses to growers. Phasmarhabditis is a genus of bacteria-feeding nematodes that can parasitize slugs and snails and thus potentially serve as a biological control agent. Canada had no record of Phasmarhabditis until a survey conducted in 2019 reported a Canadian strain of Phasmarhabditis californica from a single Arion rufus slug. To build on this discovery, we surveyed three major agricultural sites, ten greenhouses, and nurseries in Alberta from June to September 2021 to collect pest slug species and investigate their associated nematodes, specifically P. californica. Slugs were collected from the field and returned to the laboratory to check for emerging nematodes on White traps. We collected 1331 slugs belonging to nine species, with Deroceras reticulatum being the most common. Only 45 (3.38%) slug samples were positive for nematodes, and the majority were identified to species level: Alloionema appendiculatum, Caenorhabditis briggsae, Caenorhabditis elegans, Panagrolaimus subelongatus, and Mesorhabditis spiculigera. We did not isolate P. californica from any of the slugs collected from these survey sites, which included the original site where P. californica was discovered. However, four D. reticulatum slugs retrieved from a residential garden sample were infected with P. californica. These findings suggest the possibility of a fragmented distribution of P. californica across Alberta. Future research should focus on extensively surveying agriculture and horticulture sites and residential gardens in different provinces across Canada.
... The genus Phasmarhabditis includes several nematode species that are potential biological control agents for pest gastropods [27]. Currently, there are 16 nominal species of Phasmarhabditis worldwide [28], and all tested species have been shown to specifically target and kill gastropods, providing protection to various crops [29]. The genus Oscheius, which belongs to the Rhabditidae family, contains free-living nematodes that feed on 3 of 19 bacteria. ...
Effect of wireworm-damaged lettuce roots on antioxidative defence system (ascorbate-glutathione cycle, photosynthetic pigments) and movement of insect/slug parasitic nematodes towards determined root exudates was studied in a glasshouse experiment. Lettuce seedlings were grown in a substrate soil in the absence/presence of wireworms (Elateridae). Determination of antioxidants and photosynthetic pigments were analysed. Volatile organic compounds (VOC) emitted from lettuce roots were investigated by GC-MS. Herbivore induced root compounds, namely 2,4-nonadienal, glutathione and ascorbic acid, were selected for a chemotaxis assay with nematodes Steinernema feltiae, S. carpocapsae, Heterorhabditis bacteriophora, P. papillosa, and O. myriophilus. Root pests negatively affected photosynthetic pigment contents even before the appearance of visible symptoms, as protective pigments responded to the presence of reactive oxygene species (ROS). Using lettuce as a model plant, we recognised ascorbate-glutathione system as a redox hub in defense response against wireworms and analysed its role in root-exudate mediated chemotaxis of nematodes. Infected plants also demostrated increased levels of volatile 2,4-nonadienal. Entomopathogenic nematodes (EPNs, S. feltiae, S. carpocapsae, and H. bacteriophora) proved to be more mobile than parasitic nematodes O. myriophilus and P. papillosa towards chemotaxis compounds. Among them 2,4 – nonadienal repelled all tested nematodes. Most exudates that are involved in belowground tritrophic interactions remain unknown but an increasing effort is being made in this field of research. Understanding more of these complex interactions would not only allow a better understanding of the rhizosphere but could also offer ecologically sound alternatives in pest management of agricultural systems.
... * For the correction of the species name (bonaquense/bonaquensis) please see the Editor's comment inIvanova & Spiridonov (2022). ...
A new nematode species, Phasmarhabditis villasmundi sp. n., was isolated from land gastropods in the Villasmundo-S. Alfio Nature Reserve in Syracuse Province, Sicily. Phasmarhabditis villasmundi sp. n. is characterised by the presence of males and females in the population and is recognised mainly by a conical female tail with prominent phasmids at its mid-length, spicules ca 82 μ m long with a hole at the distal tip, infective juveniles with an average length of 773 μ m and the distinct molecular characteristics of the new species. It is the second member of the genus described from Italy apart from P. apuliae Nermut’ et al ., 2016 and is morphologically closest to this species. However, phylogenetic analyses based on ITS and D2-D3 LSU placed P. villasmundi sp. n. close to European P. neopapillosa and P. hermaphrodita , while P. apuliae appeared to be related to P. bohemica and the New World’s P. californica .
... Parasitic nematodes within the genus Phasmarhabditis can be effective biological control agents against pestiferous gastropods with more targeted results compared to molluscicides (Rae et al., 2007). There are currently 16 nominal species of Phasmarhabditis worldwide (Wilson et al., 1993;Azzam, 2003;Huang et al., 2015;Nermut et al., 2016a,b;Tandingan De Ley et al., 2016;Ivanova and Spiridonov, 2017;Nermut et al., 2017;Pieterse et al., 2017;Ross et al., 2018;Pieterse, 2020;Zhang and Liu, 2020;Ivanova and Spiridonov, 2021). All species tested for their biological control potential have been shown to specifically target and kill gastropods, providing protection to a variety of crops (Wilson et al., 1993;Rae et al., 2007;Mc Donnell et al., 2018b, Mc Donnell et al., 2020Nermut et al., 2020;Tandingan De Ley et al., 2020). ...
Three species of Phasmarhabditis were recovered from 75 nurseries and garden centers in 28 counties in California during fall and winter 2012–2021. A total of 18 mollusk species were recovered, most of them invasive. Nematodes were identified by sequencing the D2-D3 expansion segments of the large subunit (LSU or 28S) rRNA. Based on these surveys, P. californica was the most widespread species (37 isolates, 53.6% recovery); followed by P. hermaphrodita (26 isolates; 37.7% recovery); P. papillosa and a closely related P. papillosa isolate (6 isolates; 8.7% recovery). Nematode isolates were mainly collected from four invasive slugs (Deroceras reticulatum, D. laeve, Arion hortensis agg, Ambigolimax valentianus) and snails (Oxychilus spp. and Discus spp.). Results suggest that P. californica and P. hermaphrodita share an ecological niche in Northern, Central, Coastal, and Southern California, north of Los Angeles County.
Certain slug species are considered agricultural and horticultural pests worldwide. Nematodes offer a potential solution as biocontrol agents in controlling slug populations due to their natural associations with terrestrial gastropods. In some cases, they provide higher specificity and more efficient pest management outputs than many chemical or physical practices currently available. One of the most well-known biocontrol agents of slugs is a facultative parasite, Phasmarhabditis hermaphrodita, which has been widely established as a biocontrol agent after
it was patented and commercialized as a molluscicide product (Nemaslug ® with the associated bacteria symbiont, Moraxella osloensis) in 1994 in the UK. However, Canada had no previous record of any Phasmarhabditis species until a recent discovery of a Canadian strain of P. californica collected from a local nursery in Edmonton, Alberta. This species was originally isolated from California and subsequently marketed by BASF as a biocontrol agent (Nemaslug® 2.0) against slugs in England, Scotland, and Wales in 2022. However, the immediate use of this species as a biocontrol agent is currently not available in Canada until a
proper risk assessment of the biocontrol product Nemaslug 2.0 with the active organisms P. californica (with the bacteria symbiont, Moraxella osloensis) is made and its biology fully understood. First, I conducted an extensive survey to identify the diversity, distribution, and abundance of pest slug species and their associated nematodes in selected agricultural and horticultural sites in Alberta. I further investigated if any Phasmarhabditis species were present in the survey sites. I collected 1331 slugs belonging to nine species, with Deroceras reticulatum being the most common. Forty-five samples (3.38%) were positive for nematodes, the majority were identified to species level: Alloionema appendiculatum, Caenorhabditis briggsae, Caenorhabditis elegans, Panagrolaimus subelongatus, and Mesorhabditis spiculigera. I did not isolate P. californica from any of the slugs collected from these survey sites, which included the original site where P. californica was discovered. However, four D. reticulatum slugs retrieved from a residential garden sample were infected with P. californica, thereby suggesting a
possible fragmented distribution for this strain in the province. I then used an agar-based chemotaxis assay to evaluate the host preference of the laboratory-cultured Canadian strain of P. californica against four pest slug species, D. reticulatum, A. rufus, A. fasciatus, and A. valentianus. I showed that P. californica was strongly attracted to mucus of all slug species except for D. reticulatum for which I observed a weak attraction. In addition, I checked the host preference of a co-occurring nematode, Pristionchus entomophagus, a necromenic nematode on the same host species to check if they would have a similar host preference as P. californica. P.
entomophagus showed a significant attraction to the mucus of D. reticulatum while being strongly repulsive to A. rufus. Given that these two nematode species have potential similarities in chemoattraction profiles towards D. reticulatum, I then investigated the efficacy of the infectivity of P. californica as a biocontrol agent in the presence of P. entomophagus. The ability to cause mortality in slugs infected by P. californica was the same in single and mixed infections, i.e., mortality rates remained the same despite its co-occurrence with P. entomophagus. Both in single and mixed infection treatments, the number of P. californica that entered the slug host also remained comparable and statistically non-significant. However, the
number of progeny (F1) in mixed treatments was lower than that of the single treatments for P. californica. Interestingly, P. entomophagus was not affected by concomitant infection with P. californica. These discoveries on the local strains of Phasmarhabditis support the possibility of using P. californica as a biological control agent within Canada. Still, further investigation is needed on the persistence and efficacy of P. californica in the presence of other nematode species in the soil community
Caucasus is known as one of the few biodiversity hotspots in Europe and is characterised by rich gastropod fauna while the nematode fauna in association with gastropods has remained largely understudied. Surveys conducted in 2019 and 2021 in the North Caucasus of the Russian Federation (Stavropol Upland and western and central parts of Krasnodar Krai) has revealed the presence of three new species of Pellioditis , a facultative parasite of land gastropods, and two species of obligate parasites, the intestinal parasite Angiostoma kimmeriense and a new, still undescribed species of a larval ectoparasite Alloionema sp. The new associations of Cruznema sp. and Rhabditophanes sp. with land gastropods were recorded for the first time in the Russian Federation. The new species of Pellioditis Dougherty, 1953 described here is based on the analysis of morphology and molecular studies of two distant and morphologically distinct strains, thermalis and sindicae. Pellioditis thermalis n. sp. was characterised by females possessing a tail of about 95–100 μm long, broadly conical in shape in the thermalis and sindicae strains, with a rounded anterior part and a subulate terminal part as long as the former; prominent phasmids located at the mid-tail, equatorial vulva position, a lateral field of three ridges (four incisions), males with spicules featuring a hole at the distal tip, ensheathed infective juveniles with average length 717 μm in the thermals strain and 771 μm in the sindicae strain, and exsheathed ones 644 μm and 682 μm, respectively. ITS-based phylogenetic analyses revealed that all Pellioditis species found in Ciscaucasia and Transcaucasia probably belong to two separate clades, with independent evolutionary histories of colonisation of this area. The entire Caucasus range area appears to serve as a biodiversity hotspot for the genus Pellioditis , presumably due to its complicated geological history and repeated isolation events for its terrestrial mollusc hosts.
Introduction:
To date nineteen nematode species in the genus Phasmarhabditis Andrássy, 1976 recorded and described. This paper describes Phasmarhabditis eagyptiaca n. sp. (Nematoda: Rhabditidae), morphologically and phylogenatically and investigate its role as bio control agent for gastropods.
Methods:
Snails infected with nematode collected from Great Cairo Egypt. Sequences of the 18S ribosomal (18S rRNA) gene performed and used for phylogenetic studies. Morphological parameter measured and the nematode photographed and illustrated. Bioassay conducted on some snails and slugs species.
Results:
Phasmarhabditis eagyptiaca n. sp. is the second new species of the genus Phasmarhabditis recorded and described in Egypt after Phasmarhabditis tawfiki Azzam2003, the fourth species from Africa and the 20th from the world. Morphological and molecular parameter showed that the new isolate is close to other species of Phasmarhabditis, especially Phasmarhabditis neopapillosa Andrássy, 1983, Phasmarhabditis hermaphrodita (Schneider, 1859) and P. tawfiki Azzam with high bootstrap supported values (99.25%, 98.85%, and 98.64%, respectively). This nematode could infect and killed all snails and slugs exposed to infection in laboratory. Phasmarhabditis eagyptiaca n. sp. differs from all previously recorded species by shorter tail of female spikey tail of male and the arrangement of genital papillae formula which different from all previous species.
Conclusion:
It could be confirmed that this nematode is a new species of Phasmarhabditis. This nematode could be considering a biological control agent for snails and slugs.
Phasmarhabditis thesamica n. sp., belonging to the family Rhabditidae, was isolated from the bodies of the invasive slug, Deroceras reticulatum in Georgia. Nematodes of this genus have never been recorded previously in Georgia. Phasmarhabditis thesamica n. sp. was characterised at morphological, morphometrical and molecular level. Females are 2052 (1863-2241) μ m long, lateral fields consisting of three protruding central ridges and four incisions. The vulval opening is in the middle of the body. The tail is conical, long, tapering to a filiform tip, with prominent rod-shaped phasmids. The reproductive system is didelphic-amphidelphic. Males are 1301 (1123-1456) μ m long, with an open peloderal bursa, which is supported by nine pairs of genital papillae 1 + 1 + 1/2 + 1 + 3, and two phasmids located close to tail tip. The molecular phylogeny of P. thesamica n. sp. inferred by using ITS, D2-D3 expansion domains of the 28S rRNA gene and the 18S rRNA gene revealed close relationships with P. clausiliiae , with high support.
A new nematode species of the genus Phasmarhabditis was isolated from the body surface of a slug (Philomycus bilineatus Benson, PB). Morphological and molecular analyses confirmed this nematode as a new species. The nematode was named Phasmarhabditis zhejiangensis sp. nov. (Nematoda: Rhabditidae) and is dioecious. In males, the open bursa with genital papillae is characterized by the formula 1-1-1-2-1-3, and the spicule length is 58μm. In female, the vulva is located approximately in the middle of the body. The nematode belongs to papillosa group because of its tail shape pointed with filiform tip. The phasmids are rod-shaped. The posterior anus is slightly swollen. P. zhejiangensis was further characterized by internal transcribed spacer (ITS), 18S rDNA and 28S rDNA sequences. After the sequencing results were compared with sequences available from the National Center for Biotechnology Information (NCBI), the maximum similarities of ITS, 18S and 28S sequences were 89.81%, 96.22% and 95.28%, respectively. Phylogenetic analyses placed Phasmarhabditis zhejiangensis sp. nov. in the genus Phasmarhabditis.
We present the latest version of the Molecular Evolutionary Genetics Analysis (MEGA) software, which contains many sophisticated
methods and tools for phylogenomics and phylomedicine. In this major upgrade, MEGA has been optimized for use on 64-bit computing
systems for analyzing bigger datasets. Researchers can now explore and analyze tens of thousands of sequences in MEGA. The
new version also provides an advanced wizard for building timetrees and includes a new functionality to automatically predict
gene duplication events in gene family trees. The 64-bit MEGA is made available in two interfaces: graphical and command line.
The graphical user interface (GUI) is a native Microsoft Windows application that can also be used on Mac OSX. The command
line MEGA is available as native applications for Windows, Linux, and Mac OSX. They are intended for use in high-throughput
and scripted analysis. Both versions are available from www.megasoftware.net free of charge.
A survey for slug-associated nematodes in five locations of East and West Flanders in Belgium revealed the presence of one new and six known slug-parasitic nematodes, Agfa flexilis (Dujardin, 1845), Alloionema appendiculatum (Schneider, 1859), Angiostoma dentiferum (Mengert, 1953), Angiostoma limacis (Dujardin, 1845), Angiostoma norvegicum (Ross et al., 2017) and Phasmarhabditis hermaphrodita (Schneider, 1859). Angiostoma norvegicum and P. hermaphrodita are recorded for the first time in Belgium. The six known species are documented by light microscopy (LM) microphotographs and informative DNA sequences. Angiostoma gandavense n. sp. (Angiostomatidae), discovered from arionid slugs, is described based on light microscopy, scanning electron microscopy (SEM) and molecular data. Based on analyses of D2D3 expansion segment of 28S and 18S rDNA sequences, this new species is found to be related to A. limacis, A. norvegicum, A. margaretae (Ross et al., 2011) and A. milacis (Ivanova and Wilson, 2009). The new species can be distinguished from these others based on morphological characters such as the distinctive mucronate structures at the tail tip of both sexes, presence of lateral ala, reflexed female ovaries and the number and arrangement pattern of male genital papillae.
A new species of nematode, Angiostoma namekuji n. sp. (Angiostomatidae: Rhabditida), is described from the intestinal lumen of the terrestrial slug Philomycidae gen. sp. collected from Oshiba Island in the Seto Inland Sea, Hiroshima Prefecture, Japan. The new species is recognized by the following characteristics: body length 2,782–3,599 (mean 3,240) μm (male); 4,666–5,532 (5,030) μm (female); lateral field present; pharyngeal corpus with valves in the bulb; male with short tail, c = 35–57 (48), with one denticle; and seven pairs of genital papillae arranged as 1+2/3+1; female with tail having small denticles on distal tip; uterus c.50% of the body size; each ovary long, starting near vulva, not coiled, reflexed and reaching uterus; ovaries not crossing each other. Our phylogenetic tree based on sequences of the nuclear 28S ribosomal RNA gene supported the generic allocation of the new species in Angiostoma Dujardin, 1845.
This paper represents a first record of the new species Phasmarhabditis tawfiki. Which was isolated from the Egyptian terrestrial snail; Eobania vermiculata Müller and the slug Limax flavus Linneaus.
Description of this species is given with illustration and comparison with other species, of the genus Phasmrhabditis.
The genus Phasmarhabditis is an economically important group of rhabditid nematodes, to which the well-known slug-parasite P. hermaphrodita belongs. Despite the commercial use of Phasmarhabditis species as an attractive and promising approach for pest control, the taxonomy and systematics of this group of rhabditids are poorly understood, largely because of the lack of diagnostic morphological features and DNA sequences for distinguishing species or inferring phylogenetic relationship. During a nematode sampling effort for identifying free-living relatives of Caenorhabditis elegans in Huizhou City, Guangdong, China, a novel species belonging to the genus Phasmarhabditis was isolated from rotting leaves. Detailed morphology of the gonochoristic P. huizhouensis sp. nov. was described and illustrated. The adult female has a robust body, a relatively short and wide buccal capsule conjoined by a rhabditiform pharynx. Females are characterized by a short cupola-shaped tail end bearing a slender pointed tip, with the junction flanked by a pair of 'rod-like' phasmids. Males have an open peloderan bursa that is supported by 9 pairs of genital papillae and 1 terminal pair of phasmids. P. huizhouensis sp. nov. is morphologically very similar to the type species Phasmarhabditis papillosa but is distinguishable by its male caudal traits. The new species is readily differentiated from other taxa in the genus by its female tail shape. Molecular phylogenetic inferences based on small subunit (SSU) and the D2-D3 domain of large subunit (LSU) ribosomal DNA genes reveal that P. huizhouensis sp. nov. forms a unique branch in both phylogenies which is genetically related to P. hermaphrodita and other parasites such as Angiostoma spp. The host associations of P. huizhouensis sp. nov. and its ability to parasitize slugs are unknown.
A survey of nematodes associated with terrestrial slugs was conducted for the first time in Norway. A total of 611 terrestrial slugs were collected from 32 sample sites. Slugs were identified by means of morphological examination, dissection of genitalia and molecular analysis using mitochondrial DNA. Twelve slug species were identified, representing four different slug families. Internal nematodes were identified by means of morphological analysis and the sequencing of the 18S rRNA gene. Of the sample sites studied, 62.5% were found to be positive for nematode parasites, with 18.7% of all slugs discovered being infected. Five nematode species were identified in this study: Alloionema appendiculatum, Agfa flexilis, Angiostoma limacis, Angiostoma sp. and Phasmar-habditis hermaphrodita. Of these species, only one nematode was previously undescribed (Angiostoma sp.). This is the first record of the presence of A. appendiculatum, A. flexilis and A. limacis in Norway.
Understanding the evolutionary history of living organisms is a central problem in biology. Until recently the ability to infer evolutionary relationships was limited by the amount of DNA sequence data available, but new DNA sequencing technologies have largely removed this limitation. As a result, DNA sequence data are readily available or obtainable for a wide spectrum of organisms, thus creating an unprecedented opportunity to explore evolutionary relationships broadly and deeply across the Tree of Life. Unfortunately, the algorithms used to infer evolutionary relationships are NP-hard, so the dramatic increase in available DNA sequence data has created a commensurate increase in the need for access to powerful computational resources. Local laptop or desktop machines are no longer viable for analysis of the larger data sets available today, and progress in the field relies upon access to large, scalable high-performance computing resources. This paper describes development of the CIPRES Science Gateway, a web portal designed to provide researchers with transparent access to the fastest available community codes for inference of phylogenetic relationships, and implementation of these codes on scalable computational resources. Meeting the needs of the community has included developing infrastructure to provide access, working with the community to improve existing community codes, developing infrastructure to insure the portal is scalable to the entire systematics community, and adopting strategies that make the project sustainable by the community. The CIPRES Science Gateway has allowed more than 1800 unique users to run jobs that required 2.5 million Service Units since its release in December 2009. (A Service Unit is a CPU-hour at unit priority).
A survey of nematodes associated with native and introduced species of terrestrial slugs was conducted in the Western Cape Province of South Africa, in order to gather new data regarding diversity and distribution. A total of 521 terrestrial slugs were collected from 35 localities throughout the Western Cape. All slugs were dissected and examined for the presence of internal nematodes. Extracted nematodes were identified using a combination of molecular (18S rRNA gene sequencing) and morphological techniques. Nematodes were found parasitizing slugs at 14 of the 35 sites examined, amounting to 40% of sample sites. Of all slugs, 6% were infected with nematodes. A total of seven species of nematode were identified in the province, including Agfa flexilis, Angiostoma sp., Phasmarhabditis sp. SA1, Phasmarhabditis sp. SA2, Caenorhabditis elegans, Panagrolaimus sp. and Rhabditis sp. Of these species, four were thought to be parasitic to slugs (A. flexilis, Angiostoma sp., Phasmarhabditis sp. SA1 and Phasmarhabditis sp. SA2), as opposed to forming necromenic or phoretic associations. Three new species of slug-parasitic nematode were identified during this study (Angiostoma sp., Phasmarhabditis sp. SA1 and Phasmarhabditis sp. SA2).
CLUSTAL X is a new windows interface for the widely-used progressive multiple sequence alignment program CLUSTAL W. The new
system is easy to use, providing an integrated system for performing multiple sequence and profile alignments and analysing
the results. CLUSTAL X displays the sequence alignment in a window on the screen. A versatile sequence colouring scheme allows
the user to highlight conserved features in the alignment. Pull-down menus provide all the options required for traditional
multiple sequence and profile alignment. New features include: the ability to cut-and-paste sequences to change the order
of the alignment, selection of a subset of the sequences to be realigned, and selection of a sub-range of the alignment to
be realigned and inserted back into the original alignment. Alignment quality analysis can be performed and low-scoring segments
or exceptional residues can be highlighted. Quality analysis and realignment of selected residue ranges provide the user with
a powerful tool to improve and refine difficult alignments and to trap errors in input sequences. CLUSTAL X has been compiled
on SUN Solaris, IRIX5.3 on Silicon Graphics, Digital UNIX on DECstations, Microsoft Windows (32 bit) for PCs, Linux ELF for
x86 PCs, and Macintosh PowerMac.
Nuclear-encoded large-subunit ribosomal DNA sequences were used to infer a phylogenetic hypothesis for 17 taxa (16 nominal species) of the genera Contracaecum and Phocascaris. Phylogenetic trees based on these data have been used to assess the validity of the taxonomic distinction between these genera, which was based on the presence or absence of certain structural features, rather than on explicit hypotheses of evolutionary history. Phylogenetic hypotheses based on parsimony, likelihood, and neighbor-joining analyses of these sequence data strongly support the hypothesis that species of Phocascaris are nested within the clade of Contracaecum species hosted by phocid seals, and are more closely related to species of the Contracaecum osculatum complex than to other Contracaecum species. Alternative tree topologies representing Phocascaris as not nested within the C. osculatum complex were significantly worse interpretations of these sequence data. Phylogenetic analysis also provides strong support for the monophyly of all taxa (Contracaecum and Phocascaris) from phocid seals, which is consistent with Berland's (1964) proposal that such species form a natural group; however, his proposal to recognize all species in phocid seals as Phocascaris, with all species from birds as Contracaecum would result in a paraphyletic Contracaecum, according to the molecular phylogenetic hypothesis.
Inference of evolutionary relationships between nematodes is severely hampered by their conserved morphology, the high frequency of homoplasy, and the scarcity of phylum-wide molecular data. To study the origin of nematode radiation and to unravel the phylogenetic relationships between distantly related species, 339 nearly full-length small-subunit rDNA sequences were analyzed from a diverse range of nematodes. Bayesian inference revealed a backbone comprising 12 consecutive dichotomies that subdivided the phylum Nematoda into 12 clades. The most basal clade is dominated by the subclass Enoplia, and members of the order Triplonchida occupy positions most close to the common ancestor of the nematodes. Crown Clades 8-12, a group formerly indicated as "Secernentea" that includes Caenorhabditis elegans and virtually all major plant and animal parasites, show significantly higher nucleotide substitution rates than the more basal Clades 1-7. Accelerated substitution rates are associated with parasitic lifestyles (Clades 8 and 12) or short generation times (Clades 9-11). The relatively high substitution rates in the distal clades resulted in numerous autapomorphies that allow in most cases DNA barcode-based species identification. Teratocephalus, a genus comprising terrestrial bacterivores, was shown to be most close to the starting point of Secernentean radiation. Notably, fungal feeding nematodes were exclusively found basal to or as sister taxon next to the 3 groups of plant parasitic nematodes, namely, Trichodoridae, Longidoridae, and Tylenchomorpha. The exclusive common presence of fungivorous and plant parasitic nematodes supports a long-standing hypothesis that states that plant parasitic nematodes arose from fungivorous ancestors.
A new species of Phasmarhabditis was isolated from the slug, Polytoxon robustum, from Nairobi, Kenya. The nematode
was identified using morphological, morphometric, molecular and phylogenetic analyses. Phasmarhabditis kenyaensis n. sp. is
characterised by an infective juvenile with the longest body length in the genus, measuring 1232 (1107-1336) μm, by the presence
of males with a bursa bearing nine bilateral pairs of genital bursal papillae and one pair of papilliform phasmids flanking the tail,
cephalate paired spicules, with an arc length of 71 (57-81) μm, as well as by females with a vulva located at the mid-body region and
a conoid tail shape, with two phasmids located at ca 40% of the tail length. The molecular phylogeny of the new species, as inferred
from its SSU (small subunit) rRNA gene, places P. kenyaensis n. sp. genetically close to undescribed phasmarhabditids from South
Africa, suggesting an African grouping, while the D2-D3 (large ribosomal subunit) and ITS region analyses relate P. kenyaensis n. sp.
to P. meridionalis, with weak bootstrap support. This is the third new Phasmarhabditis species described from the African continent,
the new species bringing the total known complement of the genus to 14 species. A morphometric compendium to all species cultured
in vivo is supplied.
A new species of Phasmarhabditis was isolated from the slug, Polytoxon robustum, from Nairobi, Kenya. The nematode was identified using morphological, morphometric, molecular and phylogenetic analyses. Phasmarhabditis kenyaensis n. sp. is characterised by an infective juvenile with the longest body length in the genus, measuring 1232 (1107-1336) μm, by the presence of males with a bursa bearing nine bilateral pairs of genital bursal papillae and one pair of papilliform phasmids flanking the tail, cephalate paired spicules, with an arc length of 71 (57-81) μm, as well as by females with a vulva located at the mid-body region and a conoid tail shape, with two phasmids located at ca 40% of the tail length. The molecular phylogeny of the new species, as inferred from its SSU (small subunit) rRNA gene, places P. kenyaensis n. sp. genetically close to undescribed phasmarhabditids from South Africa, suggesting an African grouping, while the D2-D3 (large ribosomal subunit) and ITS region analyses relate P. kenyaensis n. sp. to P. meridionalis, with weak bootstrap support. This is the third new Phasmarhabditis species described from the African continent, the new species bringing the total known complement of the genus to 14 species. A morphometric compendium to all species cultured in vivo is supplied.
Two new nematode species of Phasmarhabditis were isolated from land snails in North and West Caucasus, Russian Federation. Phasmarhabditis circassica sp. n. originated from Oxychilus sp. collected by the Nickel settlement in the Adygea Republic while P. clausiliiae sp. n. came from Clausiliidae gen. sp. in the Stavropol district. Phasmarhabditis circassica sp. n. is characterised morphologically by male spicules with a hollow tip, a widely conoid, spicate female tail, ensheathed dauer juveniles 896 (813-982) μ m long with a tiny but distinct cuticular apical cap and a long filamentous tail, and exsheathed dauers 773 (670-950) μ m long with a tail half as long as in the ensheathed dauers and with a rounded tip. Phasmarhabditis clausiliiae sp. n. is very close to P. circassica sp. n. in having similar morphological traits and is differentiated mainly in having a longer female tail of 94 (79-111) vs 82 (54-125 μ m) and the much smaller ratio c of 13.7 (10.3-18.4) vs 22.7 (16.8-27.5) and by its molecular characteristics. The molecular analysis based on partial sequences of LSU rDNA, and ITS rDNA regions has been performed and showed that the closest match for both new species was P. bohemica . Despite the morphological similarity between the species described, significant difference between these two new species was reported both for LSU rDNA and ITS rDNA.
During a survey for mollusc-associated nematodes in South Africa, a new Phasmarhabditis species was isolated from the invasive slug, Deroceras reticulatum, collected from a nursery near George in the Western Cape province. The nematode was identified using a combination of morphological, morphometric, molecular, and phylogenetic techniques. The new species, P. safricana n. sp., is characterised by the cupola-shaped tail of the female with a spike, small, non-protruding phasmids, a fingerprint-like pattern of the cuticle covering the female tail, toothlike cephalic structures of the infective juveniles, and the distinct molecular characteristics of the species. The molecular phylogeny of the new species, as inferred from its SSU and LSU rRNA gene, places P. safricana n. sp. in close proximity to P. papillosa. Virulence tests were conducted, which demonstrated that P. safricana n. sp. caused significant mortality to the European invasive slug, D. reticulatum. The new species brings the total complement of the genus to eleven species.
Phasmarhabditis bohemica n. sp. is described and illustrated from the body of Deroceras reticulatum from the village of Chelčice, the Czech Republic. Morphological and molecular data showed that the new isolate is close to other species of Phasmarhabditis, particularly P. californica and P. papillosa. Females are characterised by a body length of 2079 (1777-2222) μm and a long tapering tail with prominent papilliform phasmids located laterally in the mid-tail region. Males are 1683 (1515-1818) μm long. They have a peloderan bursa, with nine pairs of rays, 1/1/1/2/1/3, and a reflexed testis 495 (434-555) μm long. Dauer juveniles are thin, 553 (474-636) μm long, with prominent lateral fields consisting of two prominent ridges and three incisures. Small subunit (18S), ITS, and D2-D3 expansion segments of the large subunit of ribosomal DNA were used to analyse the phylogenetic relationships of sequenced species in Phasmarhabditis and other closely related species. Our preliminary observations suggest that the newly described species may be a facultative mollusc-parasitic nematode that is able to survive permanently in the saprobic phase on decaying organic matter. The ecology, morphology, and phylogenetic positions of P. bohemica n. sp. are discussed.
Phasmarhabditis bonaquaense n. sp. is described and illustrated from the body of Malacolimax tenellus, from the locality of České Švýcary near the village of Dobrá Voda, the Czech Republic. Females are characterized by a body length of 2349 (1878-2626) μm and a cupola shaped tail with a long hyaline hair-like tail tip. Extremely prominent papilla-like phasmids present. Males 1829 (1414-2121) μm long. Peloderan bursa with nine pairs of rays (papillae), 1/1/1/2/1/3. One non-paired apparent papilla-like structure located near the ventral appendage anterior to the cloaca. Prominent papilla-like phasmids located close to the tail tip. Small subunit (18S), ITS, and D2-D3 expansion segments of the large subunit of ribosomal DNA were used to analyze the phylogenetic relationships of sequenced species in the genus Phasmarhabditis and other closely related species. Phasmarhabditis bonaquaense n. sp. varied from other related nematodes both in morphological characterizations and phylogenetic analysis. The life cycle of the newly described species is not well known but it is probably a facultative, mollusc-parasitic nematode able to survive permanently in the saprobic phase on decaying organic matter.
A new nematode species belonging to the family Rhabditidae, genus Phasmarhabditis, was isolated in the city of Bari (strain BAR) and near the village Gravina (strain GRA) in Apulia, Italy, and is described herein as Phasmarhabditis apuliae n. sp. The original hosts were Milax sowerbyi and M. gagates. Females are 2623 (2262-2848) μm long with a long tapering tail. Prominent papilla-like phasmids are present. Males are 2096 (1898-2363) μm long. They have a peloderan bursa with nine pairs of rays arranged as 1 + 1 + 1 + 2 + 1 + 3. Each ray bears a single papilla. A non-paired papilla is located near the ventral appendage anterior to the cloacal aperture. Prominent papilla-like phasmids are situated close to the tail tip. Dauer juveniles have lateral fields formed from two prominent wide ridges and have three incisures. Phasmarhabditis apuliae n. sp. seems to be a facultative mollusc-parasitic nematode that is capable, in a similar manner to P. hermaphrodita, of long-term survival in the saprophytic phase on decaying organic matter. Ecology, morphology and phylogenetic relationships of Phasmarhabditis nematodes are discussed.
A new species of Phasmarhabditis and the known species P. papillosa were isolated from cadavers of invasive slugs in California. Phasmarhabditis papillosa is the type of the genus and has not previously been reported from the Americas. Both species are characterised based on morphology, morphometrics and molecular data. Molecular phylogenies were inferred from concatenated DNA sequence alignments of nearly complete SSU and the D2-D3 domains of the LSU rDNA. Phasmarhabditis californica n. sp. is characterised by a robust body, mature egg-laying specimens almost spindle-shaped when relaxed, 1.5 (1.3-1.8) mm long, tapering to a bluntly rounded anterior end with stoma about as long as lip region diam., six inner labial papillae and four outer cephalic papillae, pharynx with rounded to pyriform basal bulb, vulva located halfway along the body, hermaphroditic, didelphic, amphidelphic, and short, conoid tail constricted at one-third its length with prominent phasmids. Not a single male was found among five strains. Phasmarhabditis papillosa is gonochoristic and has a longer isthmus, pyriform basal bulb and longer, dome-shaped spicate female tail constricted halfway along its length. Sequence analysis revealed unambiguous autapomorphies for P. papillosa and P. californica n. sp. Phylogenetic analyses placed these two species in a monophyletic clade comprising Phasmarhabditis species and other gastropod-parasitic taxa.Morphology, genetic distance, reproductive strategy and nucleotide autapomorphies support the new taxon.
A new nematode genus and species associated with terrestrial gastropods from Vietnam is described and illustrated. Partial SSU and ITS rDNA sequences were obtained and subjected to phylogenetic analysis. Both morphologically and molecularly, Neoalloionema tricaudatum gen. n., sp. n. is closest to Alloionema appendiculatum, another gastropod associate. It is differentiated from A. appendiculatum by the presence of an outstretched vs reflexed testis and the absence of denticles in the stoma, by the parasitic juveniles inhabiting the pallial cavity vs the foot of the host and having six vs two lips and large sucker-like phasmids vs pore-like. The most peculiar feature of N. tricaudatum gen. n., sp. n. is the presence of paired, solid appendages located at the mid-tail region of juveniles from the pallial cavity of the host. The nature of the association between N. tricaudatum gen. n., sp. n. and its gastropod host is discussed.
A new Alaninema species associated with leaf-veined slugs (Athoracophoridae) in New Zealand is described and
illustrated. Alaninema ngata n. sp. is characterised by a very long, cylindrical body, rounded head bearing two circles of cephalic
papillae and amphids, shallow stoma with three bifid teeth, muscular, cylindroid pharynx lacking valves, enlarged, rounded cardia,
nerve ring crossing the anterior intestine, excretory pore situated just posterior to nerve ring, monodelphic females with post-median
vulva, thick-shelled eggs covered with prominent tubercles, monorchic males with short testis reflection, reduced number of male
genital papillae, strong equal spicules and gubernaculum and tail tip bearing about 20 digitate processes. It is distinguished from A.
venmansi and A. njoroensis by having a larger body size (mean 8.3 mm and 13.8 mm in males and females, respectively vs 8.2 mm
females in A. venmansi and 4.8 mm and 5.5 mm in A. njoroensis males and females, respectively) and more anterior vulval position
(V = 51.6 vs 70 and 66.4 in A. venmansi and A. njoroensis, respectively). Analyses of a partial 18S rDNA sequence indicate that A.
ngata n. sp. is affiliated to the Panagrolaimorpha. The systematic position, host range and distribution of A. ngata n. sp. are discussed.
Eine Methode wird beschrieben bei der Nematoden innerhalb 24 Stunden von der Fixierungsflüssigkeit in wasserfreies Glyzerin überführt werden. Die Nematoden werden nach Fixierung in ein Gemisch von 20 Teilen Aethanol 96%, I Teil Glyzerin und 79 Teilen Wasser gebracht. Das Aethanol in diesem Gemisch wird durch Wasserentzug im Exsiccator mit Aethanol 96% bei 35°-40°C in nicht weniger als 12 Stunden bis zu etwa 95% konzentriert. Danach wird ein Gemisch von 5 Teilen Glyzerin in 95 Teilen Aethanol 96% hinzugefügt. Dieser wird bei 40°C in wenigstens 3 Stunden zu reines Glyzerin konzentriert.
The nematode Angiostoma glandicola sp. n. found parasitizing Megaustenia sp. snails (Pulmonata: Helicarionidae) collected in Dong Nai Province, Vietnam, is described and illustrated. The new species is characterized by its unusual host location (the digestive gland) and in having: two circles of cephalic probolae, six lips each bearing two prominent papillae, amphids situated at posterior of lips, the presence of lateral alae, an enlarged stoma, a club-shaped pharynx with cuticularized valves in the bulb, the nerve ring situated on the junction of the corpus and isthmus and the excretory pore opposite the bulb. Oviparous females have a mid-body vulva position, long reflexed ovaries and short divergent uteri, and a conical tail with a slightly triangular tip. Males have long, curved, not distinctly cephalate spicules and a small gubernaculum, nine pairs of pedunculate genital papillae (GP) incorporated into the bursa (three precloacal, six postcloacal in two groups: GP 4-7 closely behind the cloaca and GP 8-9 distanced), of which GP 5 and 8 terminate on dorsal edge of the bursa and GP 8 and 9 are fused at the base, the bursa nearly reaches the tail tip, unpaired precloacal GP and a pair of ventral circumcloacal GP not incorporated into bursa. It clearly differs from other species of the genus by having cephalic probolae vs. no cephalic probolae and the specific number and disposition of male GP. A partial sequence of D2D3 large subunit (LSU) rDNA was obtained and subjected to phylogenetic analyses. Relationships within the Angiostoma genus are discussed.
Two species of nematodes, Angiostoma coloaense n. sp. and Aulacnema monodelphis n. g., n. sp. (Angiostomatidae: Rhabditida) are described from terrestrial molluscs of Vietnam. Both species are characterised by a long bowl-shaped buccal cavity and typically angiostomatid male bursal alae, spicules and gubernaculum. The new genus, Aulacnema n. g., is erected for the first reported monodelphic angiostomatid. Angiostoma coloaense n. sp. can be distinguished from other species of Angiostoma Dujardin, 1845 by having a buccal cavity length greater than its width and the absence of tail spikes on both males and females.
Phasmarhabditis meridionalis sp. n. (Nematoda: Rhabditidae) from a land snail Quantula striata (Gastropoda: Dyakiidae) from southern Vietnam
- E S Ivanova
- S E Spiridonov
- Ivanova, E.S.
Ivanova, E.S. & Spiridonov, S.E. (2017). Phasmarhabditis
meridionalis sp. n. (Nematoda: Rhabditidae) from a land snail
Quantula striata (Gastropoda: Dyakiidae) from southern
Vietnam. Russian Journal of Nematology 25, 129-140.
Angiostoma meets Phasmarhabditis: a case of Angiostoma kimmeriense Korol & Spiridonov, 1991
- E S Ivanova
- S E Spiridonov
- Ivanova, E.S.
Ivanova, E.S. & Spiridonov, S.E. (2018). Angiostoma meets
Phasmarhabditis: a case of Angiostoma kimmeriense Korol
& Spiridonov, 1991. Russian Journal of Nematology 26, 77-85.
Preliminary data on the parasite survey of terrestrial gastropods of Sicily
- E S Ivanova
- M Clausi
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