Deladenus Bonabensis n. Sp. (Tylenchomorpha: Neotylenchidae) from East Azarbaijan Province, Northwestern Iran: A Morphological and Molecular Phylogenetic Study

A population of Deladenus, representing a new species, was recovered from Bonab's Ghara-Gheshlagh lagoon. It is mainly characterized by having a long body (1051-1185 μm), long distance of anterior end to pharyngeal glands end (270-312 μm), six lines in lateral fields, and a short mucro-like differentiation on the tail tip. Furthermore, it has a small-sized stylet (8.5-11.0 μm) with three knobs, no postvulval uterine sac, and males with 24- to 28-μm-long tylenchoid spicules and penial tube. With six lateral lines, the new species is comparable with seven species of the genus: D. apopkaetus, D. brevis, D. cocophilus, D. durus, D. obtusicaudatus, D. processus, and D. ulani. It was furthermore compared with D. oryzae with an unknown number of lateral lines and D. aridus, D. obesus, and D. parvus having a different number of lateral lines but similar morphology. In the molecular phylogenic analyses using small and large subunit ribosomal DNA (SSU and LSU D2-D3 rDNA) sequences, the relationships of the new species with other species and genera were not resolved in SSU phylogeny. However, it formed a clade with Deladenus sp. and D. brevis in LSU phylogeny.

Genetic variability among native and introduced strains of the parasitic nematode Deladenus siricidicola

Sirex noctilio is an invasive Eurasian woodwasp that can kill pine (Pinus spp.) trees and has been introduced to areas of the Southern Hemisphere where plantations of introduced pines are grown. The main method of control of this invasive pest has been introduction and augmentation of a parasitic nematode, Deladenus siricidicola. The strain of D. siricidicola used for biological control of S. noctilio in the Southern Hemisphere originated in Sopron, Hungary. The genotype of D. siricidicola used for biological control sterilizes females of the strain of S. noctilio present in Australia. However, different strains of S. noctilio have been introduced to different geographic areas that have been invaded and different combinations of D. siricidicola and S. noctilio genotypes vary in whether these nematodes sterilize female S. noctilio. Moreover, even in the event of sterilization, partial sterilization can occur, where not all woodwasp eggs are compromised. Sirex noctilio has now invaded North America accidentally, putatively accompanying D. siricidicola, but these host/parasite pairings do not result in female sterilization. More information is needed about the genetic diversity of D. siricidicola both where it is native and introduced. In addition, the host range of these nematodes is necessary to understand to evaluate their potential use in areas where pine communities are native. We collected and evaluated Deladenus parasitizing S. noctilio, S. juvencus, and associated insects in Hungary, Denmark, Spain, and Italy, as well as in the United States. Phylogenetic analyses were unable to fully provide fine resolution, although some community structure was evident. Many D. siricidicola samples from Hungary had identical COI and ITS sequences to the strain of D. siricidicola accidentally introduced to North America putatively when S. noctilio invaded. The same or similar strains of D. siricidicola parasitize two different Sirex species that utilize pines as well as a Sirex parasitoid and a pine-boring beetle, demonstrating some limited variability in host specificity of this species. These results highlight the genetic diversity of Deladenus siricidicola in its native range in Europe.

Description of Deladenus brevis n. sp. (Sphaerularioidea: Neotylenchidae) from Iran: a morphological and molecular phylogenetic study

Deladenus brevis n. sp. is described and illustrated based upon its morphological, morphometric, and molecular characters. The new species is mainly characterized by its small body size (367-454 µm long females and 350, 391 µm long males) and has small lateral vulval flaps. It is further characterized by having six lines in the lateral fields, cephalic region slightly expanded, narrower adjacent to the body, short 6 to 7 µm long stylet with three posteriorly sloped knobs, no post-vulval uterine sac (PUS), conical tail, narrowing to a rounded tip, and rare males with slender tylenchoid spicules and bursa reaching the tail tip. By having six lines in the lateral fields, the new species was compared with five known species of the genus, namely D. apopkaetus, D. cocophilus, D. durus, D. obtusicaudatus, and D. persicus, having comparable number (six or seven) of lines in the lateral fields. It was further compared with D. pakistanensis having lateral vulval flaps. The differences with above-mentioned species are discussed. In molecular phylogenetic analyses using nearly full length small and large subunit ribosomal DNA (SSU and LSU D2-D3 rDNA) and cytochrome c oxidase subunit I (COI mtDNA) gene sequences, D. brevis n. sp. formed clade with species of the genus with different clade support values in Bayesian inference.