Basiria khouzestanensis, Eisvand & Nejad & Azimi, 2019

Eisvand, Payam, Nejad, Reza Farrokhi & Azimi, Sedighe, 2019, Description of Basiria khouzestanensis n. sp. (Nematoda: Tylenchidae) from Iran and its phylogenetic relationships with other species in the family, Zootaxa 4563 (3), pp. 482-490 : 483-487

Basiria khouzestanensis n. sp.

Figs 1 , 2

Description. Measurements, see Table 1.

Female. Body ventrally arcuate following heat fixation. Cuticle annuli 0.7–1.2 µm wide at mid-body. Lateral field with four incisures, 3.6–4.8 µm wide, occupying 28–30% of body diameter, with non-areolated bands. Lip region smooth and elevated, continuous with body contour, 2.4–3.1 µm high and 4–5.4 µm wide. Amphidial apertures oblique and slit-like. Stylet straight with rounded basal knobs, slightly posteriorly directed, 0.8–1.5 µm across. Dorsal pharyngeal gland orifice (DGO) 4–6 µm posterior to stylet knobs. Median bulb oval, 9–12 µm long and 4–6.6 µm wide, with a weakly developed valve; located at about the middle of the pharynx. Isthmus slender. Basal bulb short and almost pyriform to slightly cylindrical, 6–9.5 µm wide and 12–16.5 µm long. Cardia small. Excretory pore mostly at the level of anterior part of the pharyngeal bulb or rarely at the level of the beginning of the basal bulb, posterior to hemizonid. Nerve ring surrounding the middle part of the isthmus. Reproductive system monodelphic-prodelphic, composed of an outstretched ovary with oocytes arranged in a single row. Spermatheca non-offset, elongated, filled with rounded sperm, 18–36 µm long and 6.5–12 µm wide. Vulva a transverse slit lacking flaps or epiptygma. Vagina 6–7.8 µm long, about one half of body diameter. Post-vulval uterine sac (PUS) 70–77% of corresponding body width in length. Tail elongate-conoid, about equal to the vulva-anus distance, tail terminus variously shaped, mostly slightly rounded to pointed tip in some specimens with a broadly rounded to slightly clavate tip.

Male. Less frequent than female and shorter. General morphology similar to that of female, except for character states associated with sexual differences. Testis single, outstretched; Spermatocytes arranged in a single row. Spicules tylenchoid, small and slightly ventrally arcuate. Gubernaculum simple, rod-shaped. Bursa adanal, simple, with smooth margins. Tail similar to that of the female.

Type host and locality. Soil samples collected from the rhizosphere of orange ( Citrus sinensis L.) in the vicinity of Baghmalek city in Khouzestan Province, GPS coordinates: 31° 32′ 21.5″ N, 49° 50′ ″ E, southwestern Iran.

Etymology. The new species name refers to the province name where it was found.

Type material. Holotype, 13 females and 8 males paratypes deposited at the nematology laboratory of the Department of Plant Protection , Shahid Chamran University of Ahvaz , Ahvaz , Iran. Two female and one male paratypes deposited at the Wageningen Nematode Collection (WaNeCo), Wageningen, The Netherlands (collection number: WT 3724).

Diagnosis and relationships. Basiria khouzestanensis n. sp. is characterized by having short body length (430–635 µm), lateral fields composed of four incisures, with non areolated bands, cephalic region smooth and continuous with body contour, stylet 9–12.5 µm long, basal bulb short and pyriform to slightly cylindrical, V = 63.3 (58–65.5), spermatheca non-offset, tail elongate-conoid, tail tip with various shapes and males with 16.5 (15– 18) µm long spicules.

Due to the median bulb located at about the middle of the pharynx and basal bulb pyriform to slightly cylindrical, the new species comes close to B. babhi Siddiqi, 1986 , B. brevia ( Sultana, 1980) Hashim, 1985 , B. graminophila Siddiqi, 1959 , B. lauta Randhawa, Khera & Khan, 1996 and B. shahidi Khan, 1982 .

Compared to B. babhi , the new species has a shorter body (430–635 vs 740–760 µm), lower c ratio (4.9–6.7 vs 8), lower V and V ŕatio (58–65.5 vs 77–78 and 75.1–80 vs 88–89, respectively), tail tip with various shapes (pointed tip and rounded to slightly clavate vs only broadly rounded terminus).

Compared to B. brevia , the outer bands of the lateral fields in the new species are smooth (vs distinctly crenate). It also differs in longer body length (430–635 vs 390–420 µm), longer stylet and more posterior DGO (9– 12.5 vs 7.5–8.5 and 4–6 µm vs just behind the stylet base, respectively), basal bulb pyriform to slightly cylindrical (vs pyriform), longer tail (86–120 vs 71–74 µm) and male present (vs unknown).

Compared to B. graminophila , the outer bands of the lateral fields in the new species are smooth (vs distinctly crenate), basal bulb pyriform to slightly cylindrical (vs pyriform) and there are remarkable differences in 28S rRNA gene sequences. There was only one record in GenBank for sequence of D2–D3 expansion segments of 28S rRNA gene for B. graminophila . Sequence variation between new species and B. graminophila were 24.6% (133 bp).

Compared to B. lauta , the new species has basal bulb pyriform to slightly cylindrical (vs pyriform), higher c ratio (9.3–13.8 vs 5.8–6.6), more posterior DGO (4–6 vs 3.5 µm), tail tip with various shapes (pointed tip and rounded to slightly clavate vs only clavate terminus) and males present (vs unknown).

Finally, the new species also resembles B. shahidi , but differs from it by the shorter tail (86–120 vs 134–140 µm), tail tip with various shapes (vs only pointed terminus), and in shorter spicule and gubernaculum lengths (15– 18 vs 21–24 and 3.8–5.5 vs 6–7 µm, respectively).

Molecular phylogenetic status. Partial sequencing of the 28S rRNA gene (D2–D3 region) of the new species yielded a fragment of 683 nt. The result of a Blast search using this fragment revealed the highest similarity with three unidentified species of the genus Basiria ( JQ004998 , JQ004999 and JQ005000 ) with identities of 87%, 87% and 86%, respectively. A total of 42 isolates of Tylenchidae (ingroup members) and Aphelenchoididae Skarbilovich, 1974 (as outgroup taxa) were selected for LSU rDNA gene (D2–D3 region) phylogenetic analyses. This dataset comprises 822 total characters. The phylogenetic relationships between the new species and representatives of Tylenchidae , as inferred from the Bayesian inference (BI) analysis, are presented in Figure 3 . The sequenced isolate from the present study is in boldface.

All isolates of Basiria species formed one clade. The monophyly of this clade is highly supported (BPP = 0.99). The new species clusters in a subclade containing three unidentified species of the genus Basiria from Iran ( JQ004998 , JQ004999 and JQ005000 ) with high support (BPP = 1.00). B. graminophila , B. gracilis and one unidentified species of the genus Basiria ( DQ077803 ), formed another subclade with high support (BPP = 1.00).

Figures

FIGURE 1. Basiria khouzestanensis n. sp. A: Entire female, B: Female pharyngeal region, C: Female reproductive system, D: Lateral field at mid-body, E&F: Female tail, G: Male tail, H: Entire male.

FIGURE 2. Basiria khouzestanensis n. sp. A&B: Female pharyngeal region, C: Lateral field at mid-body, D: Female reproductive system, E&F: Female tail, G&H: Male tail. (Scale bars = 20 µm.)

FIGURE 3. Bayesian 50% majority rule consensus tree inferred from analysis of the D2–D3 domains of the 28S rRNA gene under the GTR+G+I model. Bayesian posterior probability values more than 50% are given for appropriate clades. The new species is in bold.