Deladenus bonabensis, Amiri Bonab & Reza Atighi & Pedram, 2023

Amiri Bonab, Mohammad, Reza Atighi, Mohammad & Pedram, Majid, 2023, Deladenus bonabensis n. sp. (Tylenchomorpha: Neotylenchidae) from East Azarbaijan province, northwestern Iran: A morphological and molecular phylogenetic study, Journal of Nematology 55 (1), pp. 1-10 : 2-9

Deladenus bonabensis n. sp. ( Table 1 ; Figs. 1 and 2 ).

Description

Free-liVinG myCetophaGous female: These are medium-size nematodes, with a slender body, gradually narrowing toward the anterior body end. Six lines are present in lateral fields. The lip reign is low, not set off from the rest of the body. The stylet is small, with three knobs at base, its shaft longer than conus. The dorsal gland orifice opens at the base of the stylet knobs. Hemizonid is at the level of the nerve ring. The S-E pore is posterior to hemizonid. A deirid is not seen. Pharynx with no median bulb, and its junction with intestine is anterior to the nerve ring. The dorsal pharyngeal gland is long, overlapping intestine. The intestine is simple, and the rectum and anus are functional. The reproductive system is monodelphic-prodelphic, with ovary outstretched, oocytes in single or double rows, oviduct tubular, spermatheca oblong-oval, filled with large sperm cells, crustoformeria with more than four cells in each row, vagina modernity sclerotized, vulva with elevated lips, no PUS, and no vulval flap. The tail is conical, uniformly narrowing to the end, with a small mucro-like differentiation at the tip.

InfeCtiVe female: An infective female specimen was not found.

ParasitiC female: A parasitic female specimen was not found.

Free-liVinG myCetophaGus male: These were present as frequently as females. General morphology and pharynx are similar to those of females. The reproductive system is monorchic. Spicules are tylenchiod. Gubernaculum is small and thin. A penial tube is present. Bursa well developed, enveloping the entire tail.

Type habitat and locality

Specimens were recovered from a soil sample collected in Ghara-Gheshlagh lagoon, Bonab, East Azarbaijan province, northwestern Iran, in December 2019. The Global Positioning System coordinate for the locality is 37°12´29˝N 45°57´57˝E.

Etymology

The specific name refers to the city of Bonab, where the new species was recovered.

Type material

Holotype female, four paratype females, and four paratype males were deposited at the WaNeCo nematode collection of the Wageningen University, The Netherlands. Four paratype females and four paratype males were deposited at the nematode collection of Faculty of Agriculture, Tarbiat Modares University, Tehran, Iran.

The LSID for this publication is urn:lsid:zoobank. o rg: p u b: 6 D 91D 72 A-AD 35 - 4 53 B - A 43 F - 459770CBB5E7.

Diagnosis and relationships

Deladenus bonabensis n. sp. is mainly delimited by 1051- to 1185-µm-long females, with six lines in the lateral fields, vulva with no lateral flaps, conical tail, and penial tube present. It is further characterized by a stylet 8.5- to 11.0-µm-long with three basal knobs. By having six lateral lines, the new species is comparable to seven species of the genus, namely D. apopkaetus Chitambar, 1991; D. breVis ; D. CoCophilus Nasira, Shahina & Firoza, 2013 ; D. durus; D. obtusiCaudatus Bajaj, 2015; D. proCessus Tomar, Somvanshi & Bajaj, 2015 ; and D. ulani Sultanalieva, 1983. It was further compared with D. oryzae Bajaj, 2015, with an unknown number of lateral lines, and D. aridus Andrássy, 1957 ; D. obesus Thorne, 1941; and D. parVus Zell, 1985, having a different number of lateral lines, but similar morphology. The comparisons with the aforementioned species follow.

Deladenus bonabensis n. sp. is distinguished from D. apopkaetus by its longer body (1051–1185 vs. 612–840 µm), absence of pharyngeal chamber (vs. its presence), shorter stylet (8.5–11.0 vs. 11.9– 13.5 µm) and S-E pore posterior to hemizonid (vs. well anterior to hemizonid) with a simple (vs. cuticularized) duct.

The new species is distinguished from D. breVis by longer females and males (total range) (940–1185 vs. 367–454 µm), no flap on the vulva (vs. its presence), a mucro-like differentiation at the tail tip (vs. not), a longer stylet (8.5–11.0 vs. 6–7 µm), greater V value (93.5–95.0 vs. 87.2–90.3), and longer spicules (24–28 vs. 11.3–14.5 µm) and gubernaculum (7–8 vs. 3.4–4.5 µm).

D. bonabensis n. sp. differs from D. CoCophilus in its longer females (1051–1185 vs. 550–930 µm), S-E pore after hemizonid (vs. hemizonid after S-E pore) at 147- to 181-μm distance from anterior end (vs. 65.6–84.0 µm), longer tail (36–46 vs. 22.4–28.0 µm), longer spicules (24–28 vs. 16–18 μm) and gubernaculums (7–8 vs. 4.0–5.6 μm), and tail tip shape (having a mucro-like differentiation vs. widely rounded).

It is distinct from D. durus (data according to Chitambar, 1991) by six vs. six or seven lines in lateral field, absence of pharyngeal chamber (vs. presence), weakly deveopled metacorpus (vs. developed) and S-E pore far from hemizonid (vs. close).

Deladenus bonabensis n. sp. is distinguished from D. obtusiCaudatus mainly by its tail shape (conical, having a mucro-like differentiation at the tip vs. short and cylindrical with a broadly rounded to truncated terminus), S-E pore posterior to hemizonid (vs. anterior), and longer females (1051–1185 vs. 730 µm).

Compared with D. proCessus , D. bonabensis n. sp. is characterized by longer females (1051–1185 vs. 760–990 µm), higher c value (23.5–29.5 vs. 19.6–22.8), greater V value (93.5–95.0 vs. 92.2– 93.5), longer stylet (8.5–11.0 vs. 6–7 μm), and longer spicules (24–28 vs. 15–16 μm) and gubernaculums (7–8 vs. 3–4 μm).

Deladenus bonabensis n. sp. is distinguished from D. ulani by longer females (1051–1185 vs. 676– 787 µm), greater c value (23.5–29.5 vs. 20.0–21.0), absence of PUS (vs. presence), greater V value (93.5–95.0 vs. 82.0–83.0), and tail tip shape (having a mucro-like differentiation vs. bluntly rounded).

The new species differs from D. oryzae with a not obese (vs. obese) body (a = 39–48 vs. 25–26), a longer (1051–1185 vs. 660–960 µm) body, S-E pore posterior to hemizonid (vs. anterior), longer spicules (24–28 vs. 16–18 μm), and tail tip shape (having a mucro-like differentiation vs. bluntly rounded).

Deladenus bonabensis n. sp. is dinstinguished from D. aridus (data from Andrássy, 2007), by its longer body (1051–1185 vs. 700–880 μm), six (vs. four) lines in the lateral field, greater a value (39–48 vs. 31–37), greater c value (23.5–29.5 vs. 18.0–20.0), and greater V value (93.5–95.0 vs. 91.0–92.0).

Compared with D. obesus (data from the original description), D. bonabensis n. sp. is characterized by a longer stylet (mean = 9.5 vs. 7 µm), greater a value (39–48 vs. 10–16), greater b value (8.0–9.5 vs. 5.0–6.0), lower V value (93.5–95.0 vs. 95–99), longer distance between vulva and anus (vs. very short) and six (vs. eight to ten) lines in the lateral field according to Chitambar (1991).

Deladenus bonabensis n. sp. is dinstinguished from D. parVus by its longer body (1051–1185 vs. 388–600 μm), six (vs. four) lines in the lateral field, and greater V value (93.5–95.0 vs. 79.8–85.4).

Molecular profiles and phylogenetic status

Sequencing of SSU and LSU rDNA D2-D3 fragments of the new species yielded a single partial SSU 908 nucleotides long, and an LSU D2-D3 sequence 674 nucleotides long. The BLAST search using the SSU sequence revealed that it has 98.79% (three mismatches) and 98.68% (12 mismatches and nine gaps) identity with two sequences assigned to Tylenchidae sp. ( LC 382046 and LC382045, respectively). Its identity with all other SSU sequences was less than 98%. The BLAST search using the LSU sequence revealed it has a 99% (six mismatches and two gaps) identity with a sequence assigned to Sphaerularioidea sp. ( MW 577121). The identity with currently available LSU sequences of relevant genera was less than 90%.

Seventy-one sequences (including the newly generated sequence of the new species and three sequences of classic rhabditids as outgroups) were used in SSU phylogeny (species names and accession numbers are available in the SSU tree). Their alignment included 1,761 characters, 658 of which were variable. Fig. 3 represents the phylogenetic tree reconstructed using this data set. The sequences of Deladenus species occupied different placements in this tree and the relationships of the newly generated SSU sequence of the new species with other sequences were not resolved due to polytomy.

Seventy sequences (including the newly generated sequence of the new species and three sequences of classic rhabditids as outgroups) were used in LSU phylogeny (species names and accession numbers are available in the LSU tree). The LSU alignment was composed of 1,023 total characters, of which 796 were variable. Fig. 4 represents the phylogenetic tree inferred using this data set. In this tree, the LSU sequences of Deladenus spp. have occupied different placements in the tree, and the the new species has formed a clade with an unidentified sequence ( Sphaerularioidea sp., MW 577121). The former clade is in sister relation with the LSU sequence of D. breVis ( MT 009494).

Figures

Figure 1: Line drawings Of DeladeNUS bONabeNSiS n. sp. A: Mycetophagous female; B: Mycetophagous male; C: Anterior body region, female; D: Posterior body region, female; D1: Tail tip, female; E: Posterior body region, male; F: Parts of reproductive system, female; G: Lateral lines, female.

Figure 2: Light micrographs of DeladeNUS bONabeNSiS n. sp. A: Anterior body region, female; B: Anterior body region, male; C: Part of pharynx, female, showing the position of secretoryexcretory pore and hemizonid (upper arrow showng hemizonid, lower arrow showing the secretory-excretory pore); D: Lateral lines, female; E & F: Posterior body region, female; G: Posterior body region, male; H: Spicules and gubernaculum, male; H1: Penial tube, male. All scale bars = 10 µm.

Figure 3: Bayesian 50% majority rule consensus tree of DeladeNUS bONabeNSiS n. sp. based on small subunit (SSU) rDNA sequences under GTR + I + G model. Bayesian posterior probability values more than 0.50 are given for appropriate clades. The new sequence is indicated in bold.

Figure 4: Bayesian 50% majority rule consensus tree of DeladeNUS bONabeNSiS n. sp. based on large subunit (LSU) rDNA D2-D3 sequences under GTR + I + G model. Bayesian posterior probability values more than 0.50 are given for appropriate clades. The new sequence is indicated in bold.

Tables

Table 1. Morphometrics of DeladenUS BOnaBenSIS n. sp. All measurements are in µm and in the form: mean ± standard deviation (range).

	Holotype	Paratypes
Characters	Female	Females	Males
n	1	9	8
L	1085	1088 ± 45 (1051–1185)	986 ± 32 (940–1039)
a	42.7	42.7 ± 3.0 (39–48)	46.5 ± 5.5 (38.5–57.5)
b	9.0	9.0 ± 0.5 (8.0–9.5)	8.8 ± 0.5 (8.5–9.5)
b´	3.7	3.8 ± 0.2 (3.5–4.0)	4.0 ± 0.3 (3.8–4.7)
c	27.0	27.0 ± 2.5 (23.5–29.5)	26.0 ± 4.0 (20.5–33.5)
c´	2.3	2.5 ± 0.3 (2.0–3.0)	2.5 ± 0.3 (2.2–3.0)
V or T	94.5	94.2 ± 0.5 (93.5–95.0)	52.5 ± 3.5 (48.5–58.5)
Lip region height	2	2.3 ± 0.2 (2.0–2.5)	2.5 ± 0.1 (2.2–2.5)
Lip region width at base	7.5	7.3 ± 0.7 (6–8)	7.0 ± 0.3 (6.5–7.5)
Lip region width at the apex	5.7	5.5 ± 0.5 (5.0–6.5)	5.5 ± 0.5 (5–6)
Max. body dim.	26	25.5 ± 2.0 (22–28)	21.5 ± 3.0 (17–27)
Pharynx	124	123 ± 7 (114–135)	112 ± 6 (101–122)
Anterior end to the end of pharyngeal glands	272	289 ± 18 (270–312)	243 ± 21 (205–267)
Reproductive tract	683	655 ± 41 (574–705)	517 ± 33 (488–561)
Anterior end to vulva	1021	1025 ± 44 (982–1120)	—
Stylet total length	9	9.5 ± 1.0 (8.5–11.0)	9.5 ± 0.5 (9.0–10.5)
Stylet conus	4	4.0 ± 0.5 (3.5–5.0)	4.0 ± 0.5 (3.5–4.5)
Anterior end to DGO	11.5	12.0 ± 1.0 (11.0–13.5)	—
Secretory-excretory pore from anterior end	158	163 ± 11 (147–181)	149 ± 17 (134–185)
Nerve ring from anterior end	112	116 ± 7 (108–127)	112 ± 14 (97–140)
Hemizonid from anterior end	148	148 ± 6 (140–159)	137 ± 19 (119–178)
Vulval body diameter	27	25 ± 2 (21–28)	—
Anal body diameter	18	17.0 ± 1.5 (15–19)	15.0 ± 1.5 (13–18)
Tail	40	40.5 ± 3.5 (36–46)	39.0 ± 6.5 (30–51)
Spicules	—	—	25.5 ± 1.5 (24–28)
Gubernaculum	—	—	7.0 ± 0.5 (7–8)