Report of Six Dorylaim Nematodes from Arasbaran Forestry- Iran

Nematodes are an abundant and very diverse group among the living organisms of soils. They are few information about them as animals which can live in all habitats including fresh waters, marines, soil of farms, gardens, forests and pastures. In addition to plant parasitic nematodes, which have parasitic relationship with different plants in agricultural soils, nematodes belonging to other trophic groups also have indirect impacts on the growth of plants in the agroecosystems and nature. They are used as biological indicators of soil health. The knowledge on their abundance, presence or absence of different groups of nematodes in the soils are considered important in various biological sciences.

In order to study the diversity of dorylaimid nematodes in Arasbaran forests, 65 soil samples were collected during 2015-2016 from different plant rhizosphere. The soil samples were transferred to the Nematology laboratory- University of Tabriz and kept at four degree centigrade until extraction time. They processed and the nematodes extracted, killed, fixed and transferred to anhydrous glycerin using common nematology methods. After preparing permanent microscopic slides, their morphometric and morphological characteristics were studied under optical microscope and identification was done using related valid literature. The morphometric data of nematode and microscopic images prepared using Motik optical microscope connected to scaled lens and future wine camera, respectively. All figures were prepared by Corel draw® 12 software.

As a result 20 dorylaim species (Crassolabium saccatum, C. himalum, C. ettersbargense, Syncheilaxonchium nairi, Paravulvus hartingii, Eudorylaimus spaulli, Epidorylaimus lugdunensis, Nygolaimus brachyuris, Paraxonchium carmenae, Metaxonchium persicum, Aulolaimus oxycephalus, A. nanocephalus, Discolaimus mariae, Longidorella soadi, Sectonema demani, Xiphinema macroacanthum, X. vuittenezi, X. uthahense, Longidorus africanus, Tylencholaimus constricus, T. tahatikus, Xiphinemella globilabiata, Enchodelus macrodorus which are belonging to 16 genera and ten different families. The family Qudsianematidae had more number of genera (five) and two genera, Crassolabium (three species) and Xiphinema (three species) were found having the most number of species compared to the other genera. Six species namely Discolaimus mariae, Crassolabium saccatum, C. himalum, C. ettersbargense, Xiphinema uthahense and Tylencholaimus tahatikus that are new records for Iran nematode fauna described here in.

mariae has been reported for the first time around the roots of olive trees in Spain by Pen-santiago. In this study, the nematode was collected and identified in Arasbaran forests -Shirin Bolagh. Comparing the present population of D. mariae with its main description there were not much differences. The only difference was in the c index (80-95 vs. 88-73).

The closest species to C. saccatum is C. circuliferum which distinguished from that by non-sclerotized vulval region in C. saccatum. C. diversum as another related species to C. saccatum is characterized by a complete offset head (vs. relatively offset head) and posterior position of vulva (V= 52.9-57 vs. V = 49-50).
This population of C. ettersbargense can be compared to the morphometric characteristics of previous reports that has shorter body length (0.5-0.6 mm vs. 0.6-1 mm). In members of Crassolabium having equal to less than one millimeter body length is characteristic of C. ettersbergense, C. medianum, C. pumilum, C. goaens and C. pumilum. C. medianum species has bubble-like organs in the tail (vs. absence of them in C. ettersbergense). C. pumilum has no pars refringense, and the expanded part of the esophagus is one third of length of the esophagus (vs. absencs pars refringense in C. ettersbergense, and the above ratio is 50-60% of the esophagus). C. goaens distinguished from C. ettersbergense with longer Odontostyle (15-17 vs. 11-12 µm). The head in C. parvulum, is different in comparing C. ettersbergense (continues vs. offset).
Crassolabium himalum comparing the main description has slightly longer tail (25-27 vs. 21-24 μm. C. himalum is comparable for morphological traits with C. neohimalum and C. porosum. The C. neohimalum is characterized by a shorter body length (1.07-1.35 mm vs. 1.32 to 1.47 mm) and the asymmetrical lips (vs. symmetrical). The C. himalum is also distinguished from C. porosum by having offset head- (vs. countinouse) and a relatively tall tail (25-27 μm versus 21).
Xiphinema uthahense is member of Xiphinema americanum - group and compared to the main description and previous reports, there was no significant difference between the morphological traits and the morphology. The species X. taylori, due to the lower coefficient b (5.6-7.5 vs. 8-8.5), has a lower coefficient (39.3 -51 vs. 61-6605) and the coefficient c 'less (0.75 - 1 vs. 1.2-1.7) can be distinguished from X. utahense species. X. pacificum is relatively longer (5.8-7.8 vs. 8-8.5).
Tylencholaimus tahatikus in morphological characteristics has similarity to T. mongolicus and T. innebus. Compared to T. mongolicus it has a longer odontostyle (10.6 - 15 μm vs. 7-6 μm), longer tail (19-22 μm vs. 14-8 μm), greater c (44-50 vs. 24-30) and c 'is less (0 / 9-7 / 0 vs 1/2 - 1). In T. innebus, V is greater (V =62-64 vs. V= 57-53) and shorter body length (0.54-0.68 mm vs. 0.95 -0.90 mm).