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The new nematode species Poikilolaimus ernstmayri sp n. associated with termites, with a discussion on the phylogeny of Poikilolaimus (Rhabditida)
Abstract
A new rhabditid species associated with the termite Reticulitermes lucifugus in Corsica is described. Poikilolaimus ernstmayri sp. it. is unique within "Rhabditidae" in the position of the secretory-excretory pore at the level of the median pharynx bulb. The shape of the spicules and the presence of only one pair of precloacal genital papillae differentiate P. ernstmayri from the otherwise similar P. piniperdae. The geographical and ecological distribution of the 6 Poikilolaimus species is reviewed, their phylogeny is discussed, and a cladogram on species level based on morphological characters is presented. The stemspecies pattern of Poikilolaimus is reconstructed, and 53 apo- and plesiomorphies are listed. A rudimentary bursa and ail antidromously reflexed ovary are hypothesized as plesiomorphic characters. Changes of the pattern of genital papillae within Poikilolaimus are discussed in the framework of the phylogeny. A new formula to describe and compare this pattern is applied, which includes hypotheses on the loss of particular papillae. The sister taxon of Poikilolaimus is unknown. Some interesting similarities with Myolaimus, such as the structure of the cuticle, are discussed.
... Before 2009, there were at least 10 species of nematodes isolated from subterranean termites, primarily in the genus Reticulitermes (Lespès 1856, Leidy 1877, Merrill and Ford 1916, Banks and Snyder 1920, Massey 1971, Nguyen and Smart Jr 1994, von Lieven 2003, Sudhaus and Koch 2004, Poinar et al. 2006, von Lieven and Sudhaus 2008. Coptotermes species have also been investigated for the presence of nematodes: Wang et al. (2002) examined C. formosanus workers and soldiers and reported a Rhabditis sp., Carta and Osbrink (2005) described Rhabditis rainai Carta and Osbrink (Rhabditia: Rhabditidae) from C. formosanus, and Kanzaki et al. (2014) described Pseudaphelenchus sui Kanzaki and Giblin-Davis (Rhabditida: Aphelenchoididae) from the bodies of dissected C. formosanus workers. ...
... All three nematode genera are known as free-living cosmopolitan bacterivores that have the ability to reproduce asexually (Tahseen et al. 2009, Fonderie et al. 2013. As is common with other nematodes in the infraorders Rhabditomorpha, Bunonematomorpha, and Panogrolaimomorpha, respective members of the genera Poikilolaimus, Bunonema, and Halicephalobus have all been collected from aquatic, semiaquatic, and terrestrial environments such as sewage slurry, leaf litter, manure, and ditches (Blunden et al. 1987, Huseni et al. 1997, Anderson et al. 1998, Sudhaus and Koch 2004, Tahseen et al. 2009, Köhler 2011, Fonderie et al. 2012. ...
... The genus Poikilolaimus is characterized by having a smooth or striated cuticle that is often described as 'loose', a heavily cuticularized excretory duct, and two protruding setose teeth on each sector of the glottoid apparatus (Tahseen et al. 2009, Sudhaus 2011). Of the 15 described species of Poikilolaimus (Sudhaus 2011), P. piniperdae Fuchs (Fuchs 1930), P. ernstmayri Sudhaus and Koch (Sudhaus and Koch 2004), P. floridensis ), and P. carsiops Kanzaki, Li and Giblin-Davis (Kanzaki et al. 2011) were associated with wood-inhabiting insects, the latter three being isolated from termites Koch 2004, Kanzaki et al. 2009). Prior to this study, P. regenfussi was only reported from compost in Indonesia (from which it was described) and from a deep subsurface (1.4 km) gold mine in South Africa (Borgonie et al. 2015). ...
Termites and their nests are potential resources for a wide assemblage of taxa including nematodes. During dispersal flight events from termite colonies, co-occurring nematodes in the nest may have phoretic opportunities to use termite alates as transportation hosts. The two subterranean termite species Coptotermes gestroi (Wasmann) and Coptotermes formosanus Shiraki are both invasive and established in south Florida. Alates of both species (n = 245) were collected during dispersal flight events in 2015-2016 from six locations, of which 30 (12.2%) were associated with one or more species of nematodes. Species of Bunonema Jägerskiöld (Rhabditida: Bunonematidae), Halicephalobus Timm (Rhabditda: Panagrolaimidae), and Poikilolaimus regenfussi (Sudhaus) Sudhaus and Koch (Rhabditida: Rhabditidae) were isolated from 5.3, 4.9, and 0.4% of termite alates, respectively, and Bunonema and Halicephalobus were concomitant in 1.6% of alates. Additional C. formosanus alates were field-collected to establish laboratory colonies in sterilized rearing containers (SRC) to determine if alate-associated nematodes would colonize the newly established nest and/or brood. Among 1-yr-old termite colonies reared in SRCs, 26.9% of the colonies were positive for nematodes confirming that within-colony transmission of nematodes occurred. All three isolated nematode genera are free-living bacterivores capable of asexual reproduction. This suggests that these common co-occurring, termite-associated nematodes are opportunistic and facultative symbionts that receive increased opportunities of geographical dispersion through phoresy during termite dispersal flight events.
... Nematodes are also considered as pests in both human 18,19 and insect 20 fungicultural systems. Termites have commonly been reported to carry nematodes, mostly microbe-feeders in the phoretic stage [21][22][23][24][25][26][27][28][29] . In addition, nematode species associated with termites differ from those randomly sampled from soil or epiphytic nematodes, which implies that termite-associated nematodes are transferred by termites and potentially other soil invertebrates as well, and inhabit the carriers' habitats and/or nests 30,31 . ...
Fungus-growing termites forage dead plant materials from the field to cultivate symbiotic Termitomyces fungi in the nest. Termite foraging behavior and the entry of symbiotic arthropod inquilines may transfer nematodes into a nest and adversely affect fungus production. To test whether nematodes were transferred to fungus gardens by termites and inquilines, we examined the occurrence of nematodes in fungus gardens, five termite castes, and nine species of inquilines of a fungus-growing termite, Odontotermes formosanus. Our results revealed that nematodes were commonly carried by foraging termites and beetle inquilines. Numerous nematodes were found under the beetle elytra. No nematodes were found on termite larvae, eggs, and wingless inquilines. In addition, nematodes rarely occurred in the fungus garden. By observing the response of nematodes to three species of Termitomyces spp. and the fungus gardens, we confirmed that the fungus and fungus gardens are not actually toxic to nematodes. We suggest that nematodes were suppressed through grooming behavior and gut antimicrobial activity in termites, rather than through the antimicrobial activity of the fungus.
... Carta and Osbrink (2005) Oigolaimella attenuata von Lieven & Sudhaus von Lieven and Sudhaus (2008) Poikilolaimus carsiops n. sp. Kanzaki et al. (2011) Poikilolaimus floridensis Kanzaki & Giblin-Davis Kanzaki et al. (2009a) Poikilolaimus ernstmayri Sudhaus & Koch Sudhaus and Koch (2004) Pelodera scrofulata sp. nov. ...
Termites are the most dominant arthropod decomposers in the tropical forests and show high diversity and abundance. Within tropical ecosystems, they play a key role in modifying the biotic and abiotic environment. The areas of higher altitudes and extreme temperatures have restricted the distribution of termite fauna in India. The species richness is more in the north-eastern regions, compared to rest of India. Out of 337 species of termites known so far from India, about 35 have been reported damaging agricultural crops and buildings. Odontotermes is the major mound-builder, whereas Coptotermes, Heterotermes, Microtermes, Microcerotermes and Trinervitermes are the major subterranean genera occurring in India.
... In contrast, diagnosis consists of simply determining whether homologous characters are 'similar' or 'different'. It is crucial that systematists make this distinction because the two activities are as disparate as saying, "this entity looks different" and "this entity is a species" -see Kiontke et al. (2002) and Sudhaus and Koch (2004) for clear examples of this exercise. ...
... 23 In Sudhaus and Koch (2004) this species group was called the Piniperdaegroup. It was overlooked that Sudhaus (1980), in treating Poikilolaimus as a subgenus of Rhabditis, used the name piniperdae instead of the synonymous name micoletzkyi because of secondary homonymy with Rhabditis micoletzkyi W. Schneider, 1923. ...
Nematode-insect associations can often be very intricate and complex. Such associations can often give important clues about their sharing resources in the environment, interdependence for mutual benefits including transport and some antagonistic relationships too, showing competition for resources and survival. The present study gives an account of the insect species serving as carriers for the phoretic nematodes, the type of phorecy determined by the insect body parts invaded and the cuticular structures in nematodes aiding their survival and transport in the stressed conditions. The nematode species extracted from insects belong to families Rhabditidae, Bunonematidae, Diplogastridae, Cephalobidae, Panagrolaimidae and Aphelenchoididae. The insect carriers mainly belong to order Coleoptera with major representatives belonging to family Scarabaeidae. The cuticular ornamentations and extracuticular deposits in the extracted nematodes were also observed using light and electron microscopy to assess their relevance in stressed environments.
The present article focuses on the inventory of nematode-insect association, its nature, prevalence, specificity and the preferred invasion sites of nematodes in the insect hosts. The study takes into account the past records with 120 species of Rhabditidae belonging to 24 genera and 182 species of Diplogastridae belonging to 24 genera conspicuously associated with insects. The observations of a recent survey of nematodes associated with dung beetles were also included for analyses. The latter study revealed twenty-eight species of nematode harboured by twelve insect genera mainly belonging to three families viz., Carabaeidae Latreille, 1802 Latreille PA. 1802. Histoire naturelle générale et particulière des crustacés et des insectes. Ouvrage faisant suite à l’histoire naturelle générale et paticulière, composé par Leclerc de Buffon, rédigée par C. S. Sonnini. Familles naturelles des genres. Tome troisième. Paris. (Dufart) 3–467. [Google Scholar]; Reduviidae Latreille, 1807 Latreille PA. 1807. Genera crustaceorum et insectorum secundum ordinem naturalem in familias disposita, iconibus exemplisque plurimis explicata. Tomus secundus. Parisiis, Argentorati (König). 3:259. [Google Scholar] and Scarabaeidae Latreille, 1802. The insect family Scarabaeidae yielded as many as twenty-three species of nematodes whereas the species of genera Oscheius Andrássy, 1976 Andrássy, I. 1976. Evolution as a basis for the systematization of nematodes. London: Pitman, p. 288. [Google Scholar]; Pelodera Schneider, 1866 Schneider A. 1866. Monographie der Nematoden. Reimer, Berlin, p. 357. pp. [Google Scholar]; Metarhabditis Tahseen et al., 2004 Tahseen Q, Hussain A, Tomar V, Shah AA, Jairajpuri MS. 2004. Description of Metarhabditis andrassyana gen. n., sp. n. (Nematoda: Rhabditidae) from India. Int. J. Nematol. 14:163–168. [Google Scholar]; Pristionchus Kreis, 1932 Kreis HA. 1932. Beiträge zur Kenntnis pflanzenparasitischer Nematoden. Z F Parasitenkunde. 5(1):184–194. 869[Crossref] , [Google Scholar]; Koerneria Meyl, 1960 Meyl AH. 1960. Die freilebenden Erd- und Süßwassernematoden (Fadenwürmer). Leipzig, Quelle & Meyer, p. 164. [Google Scholar] and Allodiplogaster Paramonov & Sobolev in Skrjabin et al. (1954 Paramonov AA, Sobolev AA. 1954. Suborder Rhabditata Chitwood, 1933. In: Skrjabin KI, editor. The key of parasitic nematodes. Izdatel’stvo Akad. Nauk SSSR, Moscow, pp. 4, p. 95–242. [Google Scholar]) were observed to be the most common insect-associates. The insect genus, Onthophagus Latreille, 1802 was found to be associated with greatest number of nematode species.
The phylum Nematoda, a group of microscopic roundworms, is one of the most divergent and abundant groups of animals. However, their biological diversity and species richness have not been understood sufficiently. Because all nematodes are semiaquatic animals requiring moisture for propagation, they often use other animals, especially insects, as a host and carrier, in terrestrial environments. These insect-associated forms are generally termed ‘entomophilic nematodes.’ In this present chapter, the diversity of biological features of the entomophilic nematodes found in the Japanese Islands is introduced and compared with previous studies conducted in American and European regions.
Termites are very devastating insect pests of agricultural, ornamental crops and dry wood. They are social insect having strong inter-communication, due to which they are very active pests, with both positive and negative effects on the environment. They are found in every type of soil in the world, and have a broad range of species. Management of termites has been approached with a number of different strategies, especially chemical pesticides, which have other environmental site impacts. Microbial biological control is defined as the use, and proper adjustment, of natural enemies via microbial organisms, such as; fungi, virus, bacteria, and with the aim of suppression and management of insect populations. A broad range of species, from different groups of microbial organisms, have strong association with termites, and some have been recorded as parasites. Some species are currently used as commercial biological control agents of termites.
The Diplogastrina include about 290 species of free living nematodes. Traditional classifications of this taxon are not based upon hypotheses of phylogenetic relationships. The highly variable structures of the buccal cavity were examined in 21 species using light microscopy and SEM. The function of the stomatal structures was studied with the aid of video recordings of living worms. The morphological data were used to reconstruct a first outline of the phylogenetic relationships of the Dipolgastrina. A rhabditoid gymnostomatal tube which is longer than wide, a short stegostom and a small dorsal tooth as in Pseudodiplogasteroides belong to the stem species pattern of Diplogastrina. Diplogastrina with a ‘Rhabditis’-like gymnostomatal tube feed on bacteria and small fungal spores. A short and broad gymnostom as well as a right subventral tooth which forms a functional unit with the dorsal tooth were acquired step by step in the ancestral line leading to Mononchoides and Tylopharynx. The cuticularized cheilostom was divided into six plates connected by pliable regions twice independently within the Diplogastrina. The teeth-bearing posterior part of the buccal capsule can move forewards by pushing apart the plates of the cheilostom so that the teeth can get in contact with food items that are too big to be sucked into the buccal cavity. Diplogastrina with a divided cheilostom can feed not only on bacteria, but also on larger fungal spores, ciliates or other nematodes. Tylopharynx is specialized to rip apart the cell wall of fungal hyphae with the movements of a dorsal and a subventral tooth in order to suck out the contents of the fungus. This shows that the transformation of the buccal cavity in Diplogastrina is linked with an expansion of ecological niches.
As a first step toward understanding their mechanism of morphological evolution, we compare the morphology and development of the male genitalia in 10 species of Rhabditidae, the family of nematodes that includes Caenorhabditis elegans. We describe a number of variable morphological characteristics and focus in particular on the differing arrangements of the caudal papillae or rays within the acellular fan. We analyze the development of the ray cells within the epidermis of the last larval stage and identify changes in cell positions and cell contacts that underlie evolutionary changes in the arrangement of the rays. Epidermal cell positions were determined by means of indirect immunofluorescence staining with a monoclonal antibody directed towards adherens junctions. Similarities between the species in the cellular arrangements during the earliest developmental stages allow us to propose homologies between the rays in different species. Evolutionary changes in the positions and order of homologous rays are correlated with shifts in cell positions during development. The results suggest that genes for cell recognition or adhesion proteins, or pattern formation genes that regulate cell recognition or adhesion proteins, may be important foci of evolutionary change affecting morphology.
A detailed morphological description is presented of Diplogasteroides nasuensis Takaki, 1941 and D. magnus Völk, 1950, using light and scanning electron microscopy. Neoaplectana melolonthae Weiser, 1958 and Diplogasteroides (Rhabdontolaimus) berwigi Rühm, 1959 are synonymised with D. nasuensis. This gonochoristic species is distinguished from the hermaphroditic D. magnus by the dorsal metastomal decoration which consists of bristle-like protrusions instead of a more or less uniform tooth. The spermatocytes in D. nasuensis are twice as big as those in hermaphrodites of D. magnus. Dauer juveniles of D. nasuensis are considerably bigger than those of D. magnus. Dauer juveniles of both species are present on wood cockchafer (Melolontha hippocastani) larvae and adults but, on adult beetles, D. nasuensis dauer juveniles enter the genital pouch, whereas those of D. magnus are found under the hind coxae. In Germany, D. nasuensis is found only on M. hippocastani. D. magnus dauer juveniles are also found on a variety of other Scarabaeidae. Further small differences distinguish the two species. The genus Diplogasteroides is proposed to be taken in a broad sense. Several genera names are synonymised with Diplogasteroides.
Oigolaimella kruegeri n. sp. and Oigolaimella ninae n. sp. are described. Oigolaimella kruegeri n. sp. males can be recognised by the lack of the gubernacular keel characteristic of other Oigolaimella species and by the modified distribution pattern of the genital sensillae. Oigolaimella ninae n. sp. can be recognised and distinguished from the other members of the genus by the refractive cuticularised ring formed by the anterior edge of the cheilostomatal collar. Oigolaimella longicauda (Claus, 1862) n. comb. is accepted as a valid species, regarded as a senior synonym of O. agilis (Skwarra, 1921) and redescribed. Oigolaimella diplogaster (von Linstow, 1890) n. comb. is proposed. The phylogenetic relationship of Oigolaimella is discussed and an ecological characterisation of the taxon given on the basis of observations on feeding behaviour and locomotion in the habitat.
Over the last few years vulva development in nematodes has been used as a model system to study the evolution of developmental processes by carrying out cell lineage and cell ablation studies in various nematodes. Furthermore, a genetic and molecular analysis of vulva development has been initiated in Pristionchus pacificus. Evolutionary interpretation of these comparative developmental studies requires a phylogenetic understanding of nematodes. Recently, a molecular phylogeny for the phylum Nematoda has been published. Here, we place the comparative data of vulva development onto this phylogeny of nematodes to infer the direction of evolutionary change.
To understand how alterations in the molecular mechanisms underlying developmental processes generate a diversity of biological forms, comparative developmental biology can be combined with genetic analysis. The formation of the nematode vulva is one tractable system for such evolutionary developmental analysis, as much is understood about its development in Caenorhabditis elegans. In Caenorhabditis, six of twelve ventral epidermal cells form the 'vulva equivalence group'; although all six cells are competent to adopt vulval cell fates in response to an inductive signal, only three of these cells are induced to form vulval tissue.
In some species of the nematode families Rhabditidae, Neodiplogastridae and Panagrolaimidae, the number of cells in the vulva equivalence group is limited by apoptosis and decreased responsiveness to inductive signals (competence). We have initiated a genetic analysis in one of these species, Pristionchus pacificus, to understand the evolution of the specification of ventral epidermal cells that are competent to generate the vulva. A ped-4 mutation restores competence to an incompetent cell. Mutation of either of two other genes of Pristionchus cause two anterior cells that die in wild-type to survive. A ped-5 mutation causes these cells to be competent to respond to inductive signals, expanding the equivalence group. A ped-6 mutation causes these cells to form ectopic, anterior vulva-like invaginations.
During nematode evolution, apoptosis and change of competence alter the number and potency of ventral epidermal cells. The phenotypes of Pristionchus mutants suggest that alterations in homeotic gene control of anteroposterior patterning is involved in creating this cellular diversity.
The evolution of complexity relies on changes that result in new gene functions. Here we show that the unique morphological and functional features of the excretory duct cell in C. elegans result from the gain of expression of a single gene. Our results show that innovation can be achieved by altered expression of a transcription factor without coevolution of all target genes.