Description of Longidorella (Saevadorella) caspica n. sp. (Dorylaimida: Nordiidae) from north Iran

This contribution provides the morphological and molecular identification of a new species of the genus Longidorella (Saevadorella). L. (S.) caspica n. sp., was recovered from the rhizospheric soil of grasses in Mazandaran province in the seashore of the Caspian Sea. It is characterized by females with a length of 788 to 874 μm and a cephalic region with prominent papillae; and separated from the rest of the body by a remarkable constriction, an odontostyle of 32 to 33 μm, vulva at 52.5 to 59.0%, and a tail of 33 to 38 μm with a rounded tip. Males have 32 to 35 μm long spicules of dorylaimoid form and five to seven ventral supplements ending at 48 to 55 μm distance from cloacal pair. The new species was morphologically compared with seven nominal species viz. L. (S.) arenicola, L. (S.) cuspidata, L. (S.) magna, L. (S.) perplexa, L. (S.) saadi, L. (S.) saevae, and L. (S.) tharensis. It was further compared with similar species under the subgenus Longidorella (Enchodorella) viz. L. (E.) deliblatica and L. (E.) murithi. Besides morphological studies, molecular phylogenetic studies using partial sequences of D2 to D3 expansion fragments of 28S rDNA were performed for the new species and its phylogenetic relationships with other species and genera were discussed.

Morphological and Molecular Characterization of Kochinema farodai Baqri and Bohra, 2001 (Dorylaimida: Nordiidae) from California, with the First Molecular Study and an Updated Taxonomy of the Genus

Simple Summary

In this paper, a population of a free-living nematode collected from Northern California (USA) is identified and studied. The aim of the present work is to characterize a Californian population of the nematode genus Kochinema, with morphological and molecular methods. In addition, a revision of this genus is also provided including an updated diagnosis, a list of species, a key to species identification, and a compendium of their main morphometrics and distribution data.

Abstract

This paper deals with the morphological and molecular characterization of Kochinema farodai Baqri and Bohra, 2001, with an integrative approach. The finding of K. faroidai in California is a remarkable biogeographical novelty, as it is the first American record of the species. Molecular data herein obtained represent the first molecular study of the genus Kochinema. Furthermore, scanning electron microscopy (SEM) observations of a member of Kochinema are provided for the first time. Additionally, this contribution provides new insights into the phylogeny and taxonomy of the nematode genus Kochinema. A brief historical outline of the matter is presented. Then, the morphological pattern of the genus is revised and illustrated, the anterior position of amphids, whose opening is located on lateral lip, being its most relevant diagnostic feature. The phylogenetic analysis inferred from D2–D3 expansion segments of 28S rRNA gene shows that Kochinema clustered together with other dorylaimid species characterized by the absence of pars refringens vaginae and that it does not share a recent common ancestor with other members of the family Nordiidae. A likely polyphyly of the family Nordiidae is confirmed. Finally, an updated taxonomy of the genus is proposed, including a revised diagnosis, a list of species, a key to species identification, and a compendium of their main morphometrics and distribution data.

New and known species of the genus Pungentus Thorne & Swanger, 1936 (Dorylaimida, Nordiidae) from Iran

This contribution provides morphological and molecular data for one new and one known species of the genus Pungentus. The first species, P. azarbaijanensis n. sp., was recovered from the rhizospheric soil of grasses, collected in West Azarbaijan province, Iran, and was characterized by 2082-2365 μm long females having an angular lip region separated from the rest of the body by a constriction, 33-35 μm long odontostyle, vulva at 43.5-51.0%, 27.0-29.5 μm long rounded-conoid tail, and males unknown. It was compared morphologically with five species: P. angulosus, P. crassus, P. marietani, P. parapungens and P. pungens, which have didelphic-amphidelphic female reproductive system, body longer than 1.5 mm, and odontostyle longer than 20 μm. The second species, P. engadinensis, was recovered in three different regions of Iran (Mazandaran, Semnan and East Azarbaijan provinces). It was compared morphologically with some other populations reported all over the world. Besides morphological studies, molecular phylogenetic studies using partial sequences of 28S rDNA D2-D3 fragments were performed, and the phylogenetic relations of the two Iranian populations with other species and genera were discussed.

Biogeography and phylogenetic position of Enchodeloides signyensis (Loof, 1975), gen. n., comb. n. from Maritime Antarctic (Nematoda, Nordiidae)

The taxonomic position of the endemic Antarctic species Enchodeloidessignyensis (Loof, 1975), gen. n., comb. n. (= Enchodelussignyensis Loof, 1975) is discussed on the basis of morphological study, including SEM, morphometric data, postembryonic observations, and sequence data of 18S rDNA and the D2-D3 expansion fragments of the large subunit rDNA. A number of characters such as the cuticle and stoma structures, including the presence of moderately developed cuticularised ring around the oral aperture, peculiarities of pharynx expansion, size and position of the posterior pair of pharyngeal nuclei, a less complex uterus, and the position of a posterior ventromedian supplement show that this species differs substantially from the other members of the genus Enchodelus. Furthermore, both the 18S and 28S rDNA-based phylogenetic trees of the Enchodelus sequences available in the GenBank formed two distinct clusters with E.signyensis being a part of a well-supported group with species of the genus Pungentus; therefore, it is proposed that its taxonomic position should be reconsidered.

Description of Enchodorus yeatsi n. sp. (Dorylaimida, Nordiidae) from Southern Iran and Its Molecular Phylogenetic Study

Enchodorus yeatsi n. sp., a new species of the rare genus Enchodorus is described and illustrated based on its morphological and molecular characters. It was recovered from southern Iran. Females of the new species are characterized by having 1,511.3- to 1,792.5-µm long slender body, angular lip region having prominent papillae, 12- to 13-µm long odontostyle, double guiding ring, simple rod-like odontophore, didelphic-amphidelphic reproductive system, and 102- to 160-µm long elongate-conoid tail with rounded tip. Males of the new species are abundant and functional, characterized by 1,484- to 1,576-µm long body, 40- to 43-µm long spicules, 5 to 6 ventromedian supplements, and ventrally bent elongate conical tail. Compared to the type species, Enchodorus dolichurus, the new species has differences in its tail morphology and V value. These morphological differences and the separation of two species was further supported with basic differences in sequences of 28S rDNA D2/D3 and internal transcribed spacer 1 (ITS1) fragments. Compared to Enchodorus neodolichurus, it has basic differences in tail characters and spicule lengths. Molecular phylogenetic studies using partial sequences of 28S rDNA D2/D3 fragment of the new species and available sequences of Nordiidae members and several other dorylaim species/genera, revealed E. yeatsi n. sp. and E. dolichurus forming a clade with 0.81 Bayesian posterior probability (BPP). This clade forms a sister clade to the clade of Heterodorus sp. and Rhyssocolpus vinciguerrae, again with 0.81 BPP. In ITS1 tree, reconstructed using few available sequences, the new species and E. dolichurus formed a clade with 0.98 BPP.

Description of Lelenchus brevislitus n. sp. (Nematoda: Tylenchidae), an example of a cryptic species from Iran and its phylogenetic relationships with other species in the family

Lelenchus brevislitus n. sp. is described and illustrated based on morphological, morphometric and molecular data. The new species is characterised by having females with slender, 452-488 μm long, body lateral field vestigial as a plain simple band under scanning electron microscopy (SEM) in vulval region and absent in proximal and distal body ends, cephalic region short, ca 2 μm high, conical and truncate in anterior end in lateral view under SEM, dorso-ventrally flattened, amphidial pouches pocket-shaped and large under light microscopy (LM), their apertures short (ca 1 μm long in SEM) longitudinal sinuous slits remarkably wide near the small oral disc and significantly narrowing posteriad stylet, slender. 6.5-8.0 μm long, developed median bulb with distinct valvular plates, monodelphic-prodelphic reproductive system having a short post-vulval uterine sac (PUS), transverse vulval slit (V = 47.5-51.7) bearing small lateral membranes on each side, long filiform female tail (154-170 μm, c = 2.8-3.1, c′ = 21.5-28.3), and males unknown. The new species is considered to be a cryptic species inside the Tylenchidae. Morphological comparisons with all species of the genus are discussed. Phylogenetic studies were performed for further characterisation of the new species, and the results, using nearly full length 18S rDNA data, revealed it formed a clade with an isolate of L. leptosoma, both of which are in a sister clade with an isolate of Sakia. In a reconstructed phylogenetic tree using partial 28S rDNA sequences, the new species formed a monophyletic group, again with L. leptosoma, a sister clade to some Malenchus spp.

New data on two remarkable Antarctic species Amblydorylaimusisokaryon (Loof, 1975) Andrássy, 1998 and Pararhyssocolpusparadoxus (Loof, 1975), gen. n., comb. n. (Nematoda, Dorylaimida)

The taxonomic position of two antarctic dorylaimid species Amblydorylaimusisokaryon (Loof, 1975) Andrássy, 1998 and Pararhyssocolpusparadoxus (Loof, 1975), gen. n., comb. n. are discussed on the basis of morphological, including SEM study, morphometric, postembryonic and sequence data of 18S rDNA and the D2-D3 expansion fragments of large subunit rDNA. The evolutionary trees inferred from 18S sequences show insufficient resolution to determine the assignment of the two species to particular families, moreover Pararhyssocolpusparadoxus gen. n., comb. n. (=Rhyssocolpusparadoxus) previously regarded as a member of Nordiidae or Qudsianematidae, showed distant relationship both to Rhyssocolpusvinciguerrae and Eudorylaimus spp. The phylogram inferred from 28S sequences revealed that Amblydorylaimusisokaryon is a member of a well-supported group comprised of several Aporcelaimellus spp., while, no close relationships could be revealed for the Pararhyssocolpusparadoxus gen. n., comb. n. to any nematode genus. On the basis of molecular data and morphological characteristics, some taxonomic changes are proposed. Amblydorylaimusisokaryon is transferred from family Qudsianematidae to family Aporcelaimidae, and a new monotypic genus Pararhyssocolpus gen. n. is proposed, attributed to Pararhyssocolpidaefam. n. The diagnosis of the new family is provided together with emended diagnosis of the genera Amblydorylaimus and Pararhyssocolpus gen. n. Data concerning distribution of these endemic genera in the Antarctic region are also given.

Morphology and morphometrics of Heterodorus qinghaiensis n. sp. (Dorylaimida, Nordiidae) from soil samples in China

One new species of the family Nordiidae Jairajpuri & Siddiqi, 1964 from the enclosure grassland of Qinghai Province, China, Heterodorus qinghaiensis n. sp., is described and illustrated. The new species is characterized by the slender body, 1.29-1.46 mm in length; the granular lateral chord with numerous large depression plaques throughout its entirety; the lip region offset by a distinct depression; amphid goblet-shaped with aperture about half to two-thirds of corresponding body diameter; odontostyle 11-13 μm long; rod-like odontophore without basal flanges; pharyngeal basal expansion about one-third of the total neck length; didelphic genital system containing sperm; ovaries generally not reaching the sphincter level; vulva transversed and sclerotized; female tail conoid with round terminus; 3-5 spaced ventromedial supplements and spicule 32-41 μm long. It is close to H. liangi (Ahmad, Wu & Shaheen, 2002) Andrássy, 2009, H. brevidentatus (Thorne, 1939) Andrássy, 2009, H. monticola Andrássy, 2011, H. morgensis (Loof, 1988) Andrássy, 2009 and H. meghalayensis (Mushtaq, Baniyamuddin & Ahmad, 2007) Andrássy, 2009 in having inconspicuous or no lateral body pores, smaller odontostyle and ventrally curved tail.

Characterisation of an Iberian population of Rhyssocolpus iuventutis Andrássy, 1971 (Dorylaimida: Nordiidae), with a revised taxonomy of the genus

The identity and evolutionary relationships of the genus Rhyssocolpus are analysed and discussed using an integrative approach including morphological data and partial SSU-rDNA sequences. An Iberian population of R. iuventutis is characterised in detail, providing the first SEM observations of the genus. New sequences of the genera Enchodelus and Rhyssocolpus are provided for comparative purposes. Both morphological and molecular evidence support a separate status for the aforementioned two genera and Heterodorus, of which the latter and Rhyssocolpus shared a recent common ancestor, whereas Enchodelus did not, as had been traditionally assumed, occupy a close position. The Nordiidae is confirmed to be an artificial taxon. The taxonomy of Rhyssocolpus is revised and an emended diagnosis, updated list of species, key to their identification and compendium of their morphometrics are provided. Some nomenclatorial changes are also proposed: R. alleni and R. paradoxus are retained under Eudorylaimus, their original genus, whereas R. brasiliensis is transferred to Eudorylaimus as E. brasiliensis (Meyl, 1956) comb. n.