Hemicycliophora ahvasiensis n. sp. (Nematoda: Hemicycliophoridae), and data on a known species, from Iran

Abstract

Hemicycliophora ahvasiensis n. sp., recovered from the rhizospheric soil of date palm in Khuzestan province, southwest Iran, is described and illustrated based upon morphological, morphometric and molecular data. The new species is characterized by its sheath, closely fitting most of the body, cuticle with or without numerous irregular lines, sometimes appearing as blocks in distal body region. Lateral field without discrete longitudinal lines, but often with continuous broken striae or anastomoses. Continuous lip region with single annulus, slightly elevated labial disc, stylet with posteriorly sloping knobs. Vulva with or without slightly modified lips, spermatheca with sperm and tail conoid, symmetrically narrowing at distal region to form a narrow conical region. Morphologically, the new species looks similar to H. indica, H. labiata, H. siddiqii, H. tenuistriata and H. typica. The latter species appears more similar to the new species under light microscopy, but could be separated using the scanning electron microscopy and molecular data. The new species was also compared with H. epicharoides and H. dulli, two species with close phylogenetic affinities to it. The phylogenetic relationships of the new species were reconstructed and discussed using partial sequences of the D2-D3 expansion segments of large subunit, and internal transcribed spacer regions (LSU D2-D3 and ITS rDNA). Hemicycliophora conida, the second studied species, was recovered from north Iran and characterized by morphological and molecular data.

Keywords: D2-D3-LSU; H. conida; Hemicycliophora; ITS; morphology; morphometrics; phylogeny; sheath nematode; taxonomy.

Figure 1:

Line drawings of Hemicycliophora ahvasiensis n. sp. Female. A: Anterior body region; B: Spermatheca; C: Vulval region; D–F: Variation of posterior body end morphology. (Scale bar = 20 μm).

Figure 2:

Light photomicrographs of Hemicycliophora ahvasiensis n. sp. Female. A: Entire body; B, C: Anterior body region; D: Reproductive system (the arrow indicates the spermatheca); E: Spermatheca; F: Vagina; G: Posterior body region.

Figure 3:

Scanning electron micrographs of Hemicycliophora ahvasiensis n. sp. Female. A: Entire body; B, C: Anterior end showing labial region; D, E: En face view of labial area; F, G: Annuli ornamentation (the arrows indicate the excretory pore); H–L: Posterior body region.

Figure 4:

Scanning electron micrographs of Hemicycliophora ahvasiensis n. sp. Female. A–F: Mid-body annuli ornamentation.

Figure 5:

Light photomicrographs of Hemicycliophora conida Thorne, 1955 from Gilan province, Iran. A–G: Female. A: Anterior body region; B: Pharyngeal region; C: Lateral field at mid-body; D, E: Annuli ornamentation; F, G: Posterior body region; H, I: Male. H: Anterior body region; I: Posterior body region. (Scale bar = 20 μm).

Figure 6:

Bayesian 50% majority rule consensus tree inferred from analysis of the D2-D3 domains of the LSU rDNA sequences of Hemicycliophora ahvasiensis n. sp. under the GTR + G + I model. (lnL = 6023.6660; freqA = 0.2165; freqC = 0.2342; freqG = 0.3064; freqT = 0.2429; R(a) = 0.4542; R(b) = 1.5000; R(c) = 1.0798; R(d) = 0.4155; R(e) = 4.2300; R(f) = 1; Pinvar = 0.3122; Shape = 0.7157). Bayesian posterior probability values more than 0.50 are given for appropriate clades. New sequences are indicated in bold.

Figure 7:

Bayesian 50% majority rule consensus tree inferred from analysis of the ITS rRNA gene of Hemicycliophora ahvasiensis n. sp. and Iranian population of H. conida under the GTR + G + I model. (lnL = 13525.0293; freqA = 0.2348; freqC = 0.2548; freqG = 0.2520; freqT = 0.2583; R(a) = 1.6876; R(b) = 2.3417; R(c) = 1.8416; R(d) = 0.8470; R(e) = 3.6304; R(f) = 1; Pinvar = 0.1024; Shape = 0.4967). Bayesian posterior probability values more than 0.50 are given for appropriate clades. New sequences are indicated in bold.