Differentiation of Hemicriconemoides mangiferae and H. litchi (Nematoda: Criconematina) based on morphometrics and nuclear ribosomal DNA sequences

Abstract

Hemicriconemoides mangiferae and H. litchi, which have been considered as junior synonyms of H. strictathecatus, are morphologically similar, making identification difficult. In the present study, six populations of Hemicriconemoides spp. were collected from mango and litchi in Taiwan and were differentiated based on morphometrics and molecular characteristics. By comparing morphometric data from females and males, three populations collected from mango were identified as H. mangiferae and another three populations from litchi were identified as H. litchi. According to SEM, both of the H. mangiferae and H. litchi males had an areolated lateral field with four incisures; caudal alae were not found. The internal transcribed spacer (ITS) sequences of ribosomal DNA (rDNA) from these nematode populations were sequenced and aligned. The sequence identity of the ITS region was 89-95% between H. mangiferae and H. litchi populations, suggesting rDNA sequence divergence could be a taxonomic aid for species differentiation. Since H. mangiferae and H. litchi are closely related to H. strictathecatus, more rDNA sequence information could be valuable to deal with molecular phylogenetic relationships of these species in depth

Characterisation of a topotype and other populations of Hemicriconemoides strictathecatus Esser, 1960 (Nematoda: Criconematidae) from Florida with description of H. phoenicis sp. n. from the USA

“…This species has the same lip pattern configuration as that of H. strictathecatus, but the three populations of this species examined from China (intercepted in Italy) and South Africa (Tvl1948, N826) differ from H. strictathecatus due to the shorter stylet and metenchium (64-72, 62.5-68.0 and 64.5-69.5 μm, respectively, vs 70-86 μm and 53-60, 53-58 and 55-60.5 μm, respectively, vs 61.1-76.5 μm), smaller R, [122][123][124][125][126][127][128][129][130][131][132][133][134][135][136]respectively,[17][18][19][20][21][19][20][21][6][7][8][9][6][7][8][9][6][7][8]respectively,. We consider this sheathoid nematode to be H. litchi and agree with the decision by Chen et al (2011) to ascribe three Taiwan nematode samples to this species. The results of our present analyses are also in accordance with conclusions by Chen et al (2011), who proposed to maintain the validity of H. litchi.…”

“…We consider this sheathoid nematode to be H. litchi and agree with the decision by Chen et al (2011) to ascribe three Taiwan nematode samples to this species. The results of our present analyses are also in accordance with conclusions by Chen et al (2011), who proposed to maintain the validity of H. litchi.…”

“…The D2-D3 expansion segments of 28S rRNA, ITSrRNA and partial coxI gene sequences of several Hemicriconemoides from GenBank (Subbotin et al, 2005;Chen et al, 2007Chen et al, , 2008Chen et al, , 2011Yang & Zhang, 2013;Van den Berg et al, 2014) were also used for phylogenetic reconstruction. Outgroup taxa for each dataset were chosen according to previous published data ( Van den Berg et al, 2014).…”

“…Newly obtained sequences are indicated in bold. * Identified as H. litchi byChen et al (2011) and H. strictathecatus byVan den Berg et al (2014); * * identified as H. strictathecatus byVan den Berg et al (2014); * * * identified as H. mangiferae byChen et al (2011); * * * * identified as H. californianus byChen et al (2011).…”

Morphological and molecular characterisation of some Hemicriconemoides species (Nematoda: Criconematidae) together with a phylogeny of the genus

“…Although several Hemi criconemoides species, viz. H. alexis Vovlas, 1980, H. californianus Pinochet & Raski, 1975, H. chitwoodi Esser, 1960 (Loos, 1949) Chitwood & Birchfield, 1957, H. kanayaensis, H. ortonwilliamsi Ye & Siddiqi, 1979, H. parasinensis Chen & Liu, 2003, H. pseudobrachyurus De Grisse, 1964, H. strictathecatus Esser, 1960 and H. wessoni have been molecularly char acterised with the D2-D3 of 28S rRNA, ITS-rRNA or 18S rRNA genes, the relationship between species within the genus remains uncertain (Subbotin et al, 2005;Chen et al, 2007Chen et al, , 2008Chen et al, , 2011van Megen et al, 2009;Powers et al, 2011). In addition, topotype populations for most species were not included in these studies.…”