Molecular and morphological characterisation of Ektaphelenchoides ruehmi sp. n. (Nematoda: Ektaphelenchinae) from southwestern Iran

摘要

Ektaphelenchoides ruehmi sp. n. is described and illustrated based on morphological, morphometic and molecular characters. The new species is characterised by its body length of 355-487 mu m in females, a slightly off-set head, lateral field with three lines, total stylet length of 9.0-12.5 mu m, excretory pore at 55-70 mu m and hemizonid at 59-76 mu m distance from anterior end, shape of the tail in females and males and arrangement of papillae in male. The new species comes close in morphology and morphometrics to five known species of the genus, namely E. attenuata, E. musae, E. sylvestris, E. kelardashtensis and E. pini, mostly by having a long and filiform tail (posterior body). Based on molecular data (the results of the phylogenetic comparisons using sequences of 28S rDNA D2D3 expansion segment), the new species shows more similarity to E. kelardashtensis (80.8% similarity in overlapping part of partial sequences of D2D3). Compared with E. attenuata, the new species has a shorter body, shorter stylet, lower a and b values, shorter post-uterine sac, more posterior position of vulva, differences in shape of the tail and spicules of male. Compared with E. musae, the new species has shorter body, shorter stylet and post-uterine sac, lower b value and presence of male. Compared with E. sylvestris, the new species has a shorter stylet, lower a and b values, more anteriorly located vulva, greater distance between vulva-posterior body end and presence of male. Compared with E. kelardashtensis, it has a shorter stylet, lower b value and MB, greater value of vulva-posterior body end to body width in vulva ratio, lateral field with three incisures, midventral precloacal papilla (P1), difference in position of P2 and shape of tail and spicules in male. Compared with E. pini, the new species has a shorter body and stylet, lower b value and midventral precloacal papilla (P1) and the second pair of subventral papillae (P2). Molecular analyses were performed based on 757 bp partial sequences of 28S rDNA D2D3 segment and showed E. ruehmi sp. n. to be unique, but closest to E. kelardashtensis. Both species formed a clade with 0.98 Bayesian posterior probability in Bayesian inference and 87% bootstrap value in the Maximum Likelihood method