Description of Longidorus perangustus sp n. (Dorylaimida: Longidoridae), an amphimictic species from Iran

Longidorus perangustus sp. n. recovered in northern Iran is described and illustrated based on morphological, morphometric and molecular data. The new species is characterized by having an extremely slender and narrow body (a = 207-341), 6.3-8.9 mm long and an anteriorly flattened lip region, separated from the rest of the body by a depression. The odontostyle is 71-96 mu m and odontophore is 44-62 mu m long, with a simple guiding ring 21-29 mu m from the anterior end. The female reproductive system contains sperm, the c and c' ratio are 138-209 and 1.6-2.6 respectively; the conical tail is 38-51 mu m long and dorsally convex, ventrally flattened and with a rounded terminus. Contrary to reports for some other species of the genus, all four juvenile developmental stages are present. Males are functional with spicules (30-39 mu m long) as well as 7-12 ventromedial copulatory supplements. The new species resembles six known species of the genus namely L. attenuatus, L. euonymus, L. martini, L. mobae, L. pisi and L. protae by morphological and morphometric characters, but it is most similar to L. euonymus, from which it can be separated by having a narrower body as well as by differences in female tail characters and spicule length. Molecular phylogenetic analyses using partial sequences of 28S rDNA D2-D3 fragment revealed the new species forms a clade with four isolates of L. euonymous in both Bayesian inference (BI) and maximum likelihood (ML) analyses with maximal (1.00) Bayesian posterior probability (BPP) and ML bootstrap (BS) values. The phylogenetic relation of the new species with the rest species of the genus using partial sequences of internal transcribed spacer 1 (ITS1), was not fully resolved because of polytomy.