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Nematodes in the genus Phasmarhabditis can infect and kill slugs and snails, which are important agricultural pests. This useful trait has been commercialized by the corporation BASF after they mass produced a product labeled Nemaslug®. The product contains Phasmarhabditis hermaphrodita, which has been cultured with Moraxella osloensis, a bacterial strain that was originally thought to be responsible for causing mortality in slugs and snails. The exact mechanism leading to death in a Phasmarhabditis infected host is unknown but may involve contributions from nematode-associated bacteria. The naturally occurring microbial community of Phasmarhabditis is unexplored; the previous Phasmarhabditis microbial community studies have focused on laboratory grown or commercially reared nematodes, and in order to obtain a deeper understanding of the parasite and its host interactions, it is crucial to characterize the natural microbial communities associated with this organism in the wild. We sampled Phasmarhabditis californica, Phasmarhabditis hermaphrodita, and Phasmarhabditis papillosa directly from their habitats in Central and Southern California nurseries and garden centers and identified their native microbial community via 16S amplicon sequencing. We found that the Phasmarhabditis microbial community was influenced by species, location, and possibly gastropod host from which the nematode was collected. The predominant bacteria of the Phasmarhabditis isolates collected included Shewanella, Clostridium perfringens, Aeromonadaceae, Pseudomonadaceae, and Acinetobacter. Phasmarhabditis papillosa isolates exhibited an enrichment with species belonging to Acinetobacter or Pseudomonadaceae. However, further research must be performed to determine if this is due to the location of isolate collection or a species specific microbial community pattern. More work on the natural microbial community of Phasmarhabditis is needed to determine the role of bacteria in nematode virulence.

Theba pisana is an invasive snail pest which has established itself in San Diego County and some areas of Los Angeles County, California. The snail has grown to large populations in some areas and mitigation is becoming necessary to stop the spread of the species. In a previous study, three US strains of Phasmarhabditis species (P. californica, P. papillosa, and P. hermaphrodita) effectively killed juvenile (0.25 gram each, 4-6 mm wide) T. pisana in laboratory conditions at 5 times (150 IJs/cm2) the recommended dose. Based on laboratory assays, we demonstrated that the same three US strains of Phasmarhabditis can effectively kill larger adult T. pisana (0.4-1.2 gram, 11.5-15mm wide) in two weeks at the same dose. The strains were more efficient at killing T. pisana than the compared molluscicide Sluggo Plus®. Results further showed that the most virulent P. californica did not effectively kill T. pisana at lower doses of 30 IJs/cm2 and 90 IJs/cm2. Additional research is needed to develop the most efficient means of application of Phasmarhabditis to mitigate T. pisana in the field.

Theba pisana is a serious snail pest in many parts of the world and affects diverse crops including grain, vegetables, grapevines, and ornamental plants and shrubs. Due to its gregarious nature, ability to reproduce rapidly, and the difficulty of controlling it by conventional methods, it has the potential to become a significant pest where introduced. Mitigating this pest is an important challenge that must be addressed. Phasmarhabditis hermaphrodita, is a gastropod-killing nematode that is commercially available only in Europe (Nemaslug ®) and Sub-Saharan Africa (Slugtech ® SP). The use of effective gastropod-killing nematodes in the genus Phasmarhabditis (P. hermaphrodita, P. californica and P. papillosa) in California may provide one strategy for alleviating the potential damage and further spread of these snails, which are currently limited to San Diego and Los Angeles counties. Laboratory assays demonstrated for the first time that US isolates of P. hermaphrodita, P. californica and P. papillosa at 150 DJs/cm2 caused significant mortality and are equally lethal to T. pisana. Molluscicidal efficacy of these nematodes are comparable with those of iron phosphate, at the recommended high dose of 4.88 kg/m2. Additional trials are needed to determine their effects at lower dose and whether they are dependent on the size or age of the snails.

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. [ABSTRACT FROM AUTHOR]

The nematode diversity in soil and litter was investigated on Mount Hamiguitan, the Philippines, along four eco-habitats from elevations of 75-1600 m a.s.l. A total of 155 and 467 nematodes were identified to 39 and 62 genera from litter and soil, respectively. The nematode assemblages and diversity did not show any relation to eco-habitat or elevation. Bacterivorous nematodes were the most common group (37.5%). Acrobeloides was most abundant from the soil and Aphelenchoides from the litter. Bicirronema hamiguitanense n. sp. is herein described based on morphology, morphometrics and molecular data. The new species has the following diagnostic features: a wide lateral field one-fifth of its body diam. with four incisures forming two ornamented ridges; gubernaculum with proximal thickening; spicules (35-38 µm) and gubernaculum (18-20 µm) longer than B. caledoniense; and with 37 molecular autapomorphies supporting its new species status. The phylogenetic position of the new species within Cephalobomorpha is discussed. [ABSTRACT FROM AUTHOR]

Phasmarhabditis hermaphrodita is reported for the first time in North America from cadavers of the invasive slug species Deroceras reticulatum, D. laeve and Lehmannia valentiana collected from three different locations in California, USA. Four isolates were identified using combined morphology, morphometries and molecular sequence data for complete internal transcribed spacer (ITS-1, 5.8S, ITS-2), D2-D3 expansion segments of the large subunit (LSU or 28S) and nearly complete small subunit (SSU or 18S) ribosomal DNA. Extremely low sequence variations in the COI gene of the mitochondria were observed among US isolates as well as between US isolates and the two UK sequences. The occurrence of P. hermaphrodita in North America has regulatory implications for potential biological control strategies against non-native gastropod species that are pests in ornamental and agricultural cultivation on this continent. The D2-D3 sequence of the LSU rDNA is new for the species. [ABSTRACT FROM AUTHOR]

Descriptions of three known species of Cynura, i.e., C. cemmbus, C. klunderi and C. papillata, are given, including SEM micrographs of C. cerambus and a tabular compendium for all species of the genus. The phylogenetic relationships of C. klunderi are inferred from molecular data. Bayesian analyses of small subunit (SSU) of rRNA sequences support a position nested among the Plectidae suggesting the secondary simplification in the morphology of pharyngeal valvular apparatus in Cynura and the 'return' from a terrestrial to a marine environment in this genus. [ABSTRACT FROM AUTHOR]

Descriptions of eight new and three known species of Tarvaia are given. Tarvaia pacifica sp. n. has cephalic capsule reaching posterior part of short amphids, amphidial shield without ornamentation, straight vagina with pars refringens vaginae, slightly asymmetrical spicules, gubernaculum with two dorsal apophyses, precloacal ridge present; T. algicola sp. n. has cephalic capsule with unevenly thickened walls reaching posterior part of short amphids, amphidial shield without ornamentation, straight vagina, apophyses absent, precloacal ridge present; T. carolinensis sp. n. has cephalic capsule reaching posterior part of short amphids, amphidial shield with ornamentation, sigmoid vagina, gubernaculum with a dorsal apophysis; T. longispiculata sp. n. has elongated cephalic capsule reaching posterior part of elongate amphids, amphidial shield without ornamentation, sigmoid vagina, unusually long spicules, gubernaculum with dorsal apophysis, precloacal ridge present; T. inaequalis sp. n. has short cephalic capsule reaching anterior third of elongate amphids, amphidial shield with ornamentation, straight vagina, strongly anisometric spicules, gubernaculum with caudal apophysis, precloacal ridge present; T. sakhalinensis sp. n. has short cephalic capsule reaching middle of short amphids, amphidial shield with distinct pores, symmetrical spicules, apophyses absent; T. tchesunovi sp. n. has cephalic capsule with unevenly thickened walls reaching posterior part of short amphids, amphidial shield without ornamentation, symmetrical spicules, apophyses absent; and T. ricordensis sp. n. has cephalic capsule reaching posterior part of short amphids, amphidial shield without ornamentation, straight vagina, symmetrical spicules, gubernaculum with dorsal apophyses. Updated descriptions of T. donsi, T. cladara and T. gerlachi are provided. Phylogenese analysis based on 18S rDNA suggests a close relationship between Tarvaia and Desmoscolecida. [ABSTRACT FROM AUTHOR]

A population of Placodira lobata from the USA is described using both light and scanning electron microscopy and compared with the descriptions of the type specimens of the same species. The phylogenetic relationships of the species are inferred from molecular data and places P. lobata in a clade that unites genera with mostly simple morphology of the labial region, like Cephalobus, Acrobeloides, Heterocephalobellus and Metacrobeles, but also includes species of Zeldia and Chiloplacus. [ABSTRACT FROM AUTHOR]

Hemiplectus muscorum, the type and single representative of its genus, is redescribed on the basis of abundant new material collected in the UK, Canada and the USA using both light and scanning electron microscopy. The phylogenetic relationships of the species are inferred from morphological as well as molecular data. Maximum parsimony, neighbour joining and maximum likelihood analyses of small subunit (SSU) rRNA sequences support a position nested among the Plectidae. This conflicts with our morphological assumptions of character polarity, as it implies that the absence of a valvate bulb in Hemiplectus is a reversal rather than a plesiomorphy. The excretory system of Hemiplectus is described more precisely. Its structure is highly reminiscent of the system in Plectus but differs in the presence of an anterior and posterior pair of pseudocoelomocytes flanking the renette cell. A pair of lateral somatic setae is identified as possible homologues of the 'deirids' in Plectus and Rhabditida. Measurements and descriptions are given of all four juvenile stages. [ABSTRACT FROM AUTHOR]

The morphology and morphometry of nematodes of six species of the family Ceramonematidae is described using light and scanning electron microscopy. In this paper, we describe two new species and redescribe two known species of Ceramonema and one new species each of Pselionema and Pterygonema. Ceramonema altogolfi sp. n. is characterised by the 0.8-1.3 mm long body, 187-247 body annules, weakly developed zygapophyses, presence of intracuticular vacuoles, sexual dimorphism in amphid shape, presence of vaginal sclerotisation, complex gubernaculum and relatively uniform anal and cloacal annules, whilst C. inguinispina sp. n. has a 0.8-1.1 mm long body, 135-191 body annules, weakly developed zygapophyses, presence of intracuticular vacuoles, sexual dimorphism in amphid shape, absence of vaginal sclerotisation, thorn-shaped precloacal projection, plate-like gubernaculum and double cloacal annule. Pselionema psednum sp. n. is distinguished by 1.4-1.7 mm long body, 251-292 body annules, weakly developed zygapophyses, absence of intracuticular vacuoles, sexual dimorphism in amphid shape and Pterygonema mexicanum sp. n. is characterised by having amphids lacking a central thorn-like projection and pharynx with a distinct posterior glandular bulb. Populations of Ceramonema rectum and Ceramonema cf. yunfengi are also described. The male cloacal region of the species examined appears to be a rich potential source of taxonomic characters that have as yet received insufficient attention for this family. [ABSTRACT FROM AUTHOR]

Hirschmanniella santarosae sp. n. is described from the largest vernal pool in the Santa Rosa Plateau Ecological Reserve, Murrieta, California, USA. The cryptic new species is morphologically very close to H. pomponiensis and H. gracilis as it can be distinguished from the former only by a more anterior excretory pore position and by more flattened as well as laterally expanded stylet knobs, whilst it differs from the latter in the greater distance from phasmid to tail tip and in the bursal alae ending near the phasmids rather than near the tail tip. Analysis of the rDNA small subunit (SSU) and D2D3 expansion segments of the large subunit (LSU) shows that H. santarosae sp. n. is genetically distinct, having respective sequence homology of 98.89% and 95.9% with H. pomponiensis for these loci. Congruence in SSU and D2D3 gene trees as well as unambiguous character autapomorphies further support the new species status of H. santarosae sp. n. and sibling relationship with H. pomponiensis. Although many more isolates and species will need to be studied before informative biogeographic analyses can be performed, the presently available sequence data suggest that some Hirschmanniella lineages have diversified independently on either side of the Atlantic. [ABSTRACT FROM AUTHOR]

Measurements, line drawings and scanning electromicrographs are provided of Baujardia mirabilis gen. n., sp. n., isolated from pitcher fluid of Nepenthes mirabilis from Thailand. The new genus differs from all known nematodes in having two opposing and offset spermatheca-like pouches at the junction of oviduct and uterus. It also differs from most known Rhabditida in having four cephalic setae instead of papillae. Phylogenetic analysis of small subunit rDNA sequence data robustly places the new genus within Panagrolaimidae as a sister taxon to Panagrellus. These unusual nematodes resemble Panagrellus in body size (1.8-2.7 mm in females, 1.3-1.9 mm in males) and in the monodelphic, prodelphic female reproductive system with thickened vaginal walls and prominent postvulval sac. However, they differ from Panagrellus in the characters mentioned above, in their comparatively longer stegostom and in the shape of the male spicules. Because of its aberrant characters, inclusion of this new genus in Panagrolaimidae requires changes to the family diagnosis. [ABSTRACT FROM AUTHOR]

Phylogenies were inferred from nearly complete small subunit (SSU) 18S rDNA sequences of 12 species of Meloidogyne and 4 outgroup taxa (Globodera pallida, Nacobbus abberans, Subanguina radicicola, and Zygotylenchus guevarai). Alignments were generated manually from a secondary structure model, and computationally using ClustalX and Treealign. Trees were constructed using distance, parsimony, and likelihood algorithms in PAUP* 4.0b4a. Obtained tree topologies were stable across algorithms and alignments, supporting 3 clades: clade I = [M. incognita (M. javanica, M. arenaria)]; clade II = M. duytsi and M. maritima in an unresolved trichotomy with (M. hapla, M. microtyla); and clade III = (M. exigua (M. graminicola, M. chitwoodi)). Monophyly of [(clade I, clade II) clade III] was given maximal bootstrap support (mbs). M. artiellia was always a sister taxon to this joint clade, while M. ichinohei was consistently placed with mbs as a basal taxon within the genus. Affinities with the outgroup taxa remain unclear, although G. pallida and S. radicicola were never placed as closest relatives of Meloidogyne. Our results show that SSU sequence data are useful in addressing deeper phylogeny within Meloidogyne, and that both M. ichinohei and M. artiellia are credible outgroups for phylogenetic analysis of speciations among the major species.