Material examined

Twelve females from two locations, in a good state of preservation (figs 1 and 2).

Fig. 1.

Aporcella talebii sp. n.: (A) neck region; (B) amphidial pouch; (C) anterior end; (D) entire body; (E) posterior genital branch; (F) posterior body region; (G) lateral chord.

Fig. 2.

Aporcella talebii sp. n.: (A) anterior end; (B) amphidial pouch; (C) neck region; (D) entire body; (E) pharyngo–intestinal junction; (F) posterior genital branch; (G) vagina; (H) lateral chord; (I) posterior body region. Scale bars: (a–i) 10 μm; (d) 60 μm.

Measurements

The measurements are presented in table 1.

Description

• Female. Moderately slender to slender (a = 27–37) nematodes of medium size, 1.66–2.02 mm long. Body cylindrical, tapering toward both ends but more so towards the posterior end as the tail is conical. Upon fixation, body curved ventrad, from an open to a closed C. Cuticle two-layered, 2–3 μm thick at anterior region, 3–5 μm in mid-body and 4.5–6.5 μm on tail; outer layer thin and with constant thickness throughout the body, with an apparently smooth surface; inner layer visibly thicker than the outer one, especially perceptible at caudal region. Lateral chord 8–10.5 μm broad at mid-body, occupying 14–17% of the corresponding body diameter, bearing glandular bodies throughout the body. One ventral and two dorsal body pores usually present at level of odontostyle, plus odontophore in some specimens. Lip region angular, offset from the adjacent body by a constriction, 3.0–3.5 times as wide as high and about one-third (28–34%) of body diameter at neck base; lips moderately separate, with protruding labial and cephalic papillae. Amphidial fovea cup-shaped, its opening 7.5–9 μm broad or 50–60% of lip region diameter. Odontostyle typical of the genus, strong, nearly equal in length (0.9–1.1 times) to lip region diameter, its aperture 9–11 μm or 62–68% of its total length. Odontophore rod-like, 1.4–1.8 times as long as the odontostyle. Guiding ring single, plicate, located at 7–11 μm from the anterior end. Nerve ring at 31–39% of neck length from anterior end. Pharynx entirely muscular, its anterior section gradually enlarging into the basal expansion that is 7.9–8.3 times longer than wide, 3.6–4.1 times longer than body diameter at neck base and occupies up to one half (46–50%) of the total neck length, with gland nuclei situated as follows: DN = 59–60; S₁N₁ = 68–70; S₁N₂ = 77–79; S₂N = 88–91. Cardia hemispherical to conoid, 13–15 × 8.7–9.5 μm. Reproductive system didelphic–amphidelphic, with both branches equally and well developed, the anterior 287–369 μm or 16–22% of body length, the posterior one 276–387 μm or 16–21% of body length: ovaries comparatively small, in general not reaching the uterus–oviduct junction, anterior 78–109 μm and posterior 75–118 μm long, with oocytes arranged first in two or more rows, then in a single row in the maturation zone; oviduct 108–133 μm (anterior) and 98–137 μm (posterior), consisting of slender part and well-developed pars dilatata with visible lumen; sphincter present at oviduct–uterus junction; uterus a simple, tube-like structure 89–124 μm long or 1.6–2.0 times the corresponding body diameter long; vagina extending inwards 22–37 μm, reaching 38–47% of body diameter, consisting of pars proximalis 14–25 × 16–22 μm with somewhat sigmoid walls and surrounded by developed musculature, and pars distalis 4–9 μm long. Gland cells present on both sides of vagina. Vulva a transverse slit. Prerectum 1.3–2.8, rectum 0.7–1.4 times the anal-body diameter long. Tail conical with finely rounded terminus, ventrally nearly straight, dorsally first convex and then bearing a more or less conspicuous concavity, sometimes with subdigitate outline, inner cuticle continuous but not reaching the tail tip – thus, a short but perceptible terminal hyaline portion exists; caudal pores at about the middle of the tail, one nearly lateral, other subdorsal.

• Male. Not found, and females do not contain sperm cells.

Molecular characterization

Two sequences of the D2–D3 28S rDNA gene comprising about 800 bp long from two specimens belonging to different populations were obtained and deposited at the GenBank (accession numbers MH727515 and MH727511). In pairwise-distance analysis, two sequences showed seven nucleotide differences and 99% similarity. .

Diagnosis and relationships

The new species is characterized by its 1.66–2.02-mm-long body, lip region offset by constriction and 15–17 μm broad, odontostyle 14–17.5 μm or 0.9–1.1 times the lip region diameter, neck 412–484 μm long, pharyngeal expansion 209–231 μm long or 46–50% of total neck length, female genital system didelphic–amphidelphic, uterus a simple tube 89–124 μm long or 1.6–2.0 times the corresponding body diameter long, vulva a somewhat posterior (V = 52–59) transverse slit, tail conical (40–50 μm, c = 37–47, c′ = 1.1–1.4) with a weak but perceptible dorsal concavity at the end and male absent.

Aporcella talebii sp. n. is very similar to A. malekimilanii Naghavi, Niknam, Vazifeh & Peña-Santiago, 2019, another Iranian, recently described species, from which it can be easily distinguished by its much shorter pharyngeal expansion (209–231 vs. 300–375 μm, 46–50 vs. 58–63% of total neck length) and, consequently, much more posterior position of pharyngeal gland nuclei (DN = 59–60 vs. 50–52; S₁N₁ = 68–70 vs. 59–61; S₁N₂ = 77–79 vs. 70–73; S₂N = 88–91 vs. 81–86). In addition, it shows a generally smaller-sized body (1.6–2.0 vs. 1.9–2.7 mm long; neck 412–484 vs. 476–619 μm; prerectum 55–84 vs. 105–178 μm). The new species also resembles Aporcella capitulum (Shahina, Musarrat & Siddiqi, 2005) Álvarez-Ortega, Subbotin & Peña-Santiago, 2013 and Aporcella salsa (Andrássy, 2010) Álvarez-Ortega, Subbotin & Peña-Santiago, 2013. It differs from A. capitulum, only known from Pakistan, by its narrower lip region (15–17 vs. 17.5–20 μm), longer neck (412–484 vs. 356–402 μm), significantly different female tail shape (conical with a dorsal concavity vs. regularly convex conoid) and male absent (vs. as frequent as female). From A. salsa, a North American species, by its more slender body (a = 27–37 vs. 24–26), narrower lip region (15–17 vs. 19–20 μm), shorter odontostyle (14–17.5 vs. 18–19 μm), posteriorly located vulva (V = 52–59 vs. 46–52) and somewhat different tail shape (finely rounded vs. more rounded tip, presence vs. absence of a perceptible dorsal concavity and less vs. more developed terminal hyaline portion or lacuna).

Type locality and habitat

Iran, East Azarbaijan province, Sufiyan, Roodghat area, Zeinabad village (GPS coordinates: 38°18′00″N, 46°07′08″E, altitude 1540 m above sea level (a.s.l.)), from the rhizosphere of common wheat (Triticum aestivum L.).

Other locality and habitat

Iran, East Azarbaijan province, Osku, Teymourlu (GPS coordinates: 37°44′35″ N, 45°57′30″E, altitude 1456 m a.s.l.), from the rhizosphere of ‘Red Delicious’ apple (Malus domestica L.).

Type material

Female holotype female and two female paratypes deposited at the Nematode Collection of the Faculty of Agriculture, University of Tabriz, Tabriz, Iran. Four female paratypes with the Nematode Collection of the University of Jaén, Spain.

Etymology

The new species is named in honour of the late Dr Parviz Talebi Chaichi, Associate Professor of Insect Ecology, Department of Plant Protection, Faculty of Agriculture, University of Tabriz, Tabriz, Iran.

Material examined

Twenty females from four locations, in a good state of preservation (fig. 3).

Fig. 3.

Aporcella simplex (Thorne & Swanger, 1936) Loof & Coomans, 1970 anterior end, amphidial pouch, vaginae, posterior body region and lateral chord of populations from (A–F) Azarbaijan Shahid Madani University Campus; (G–L) Sheikh Hassan; (M–R) Firooz Salar; and (S–X) Mamaghan, respectively. Scale bars: 10 μm.

Measurements

The measurements are presented in table 2.

Table 2.

Morphometrics of the Iranian populations of Aporcella simplex.

All measurements are in μm (except L in mm) and in the form: mean ± standard deviation (range).

L = body length; a = body length/maximum body diameter; b = body length/neck length; c = body length/tail length; c′ = tail length/body diameter at anus; V = distance vulva-anterior end × 100/body length.

Molecular characterization

Four sequences (MH751506, MH751512, MH751513 and MH751514) c. 800 bp long of D2–D3 expansion segments of the 28S rDNA gene were obtained from four specimens belonging to different populations. In pairwise distance analysis, the three sequences MH727512, MH727513 and MH727514 showed 100% similarity, with no inter-population variation. Nevertheless, the MH727506 sequence presented a 2 bp difference, with 99% similarity to the other sequences.

Distribution

Four populations of this species were collected in four Iranian places: (i) East Azarbaijan province, Tabriz, Sheikh Hassan village (GPS coordinates: 38°01′37″N, 46°06′30″E, altitude 1315 m a.s.l.), in the rhizosphere of silver berry (Elaeagnus angustifolia L.); (ii) Mamaghan region, Azarshahr (37°49′39″N, 45°58′17.2″E, altitude 1304 m a.s.l.), in the rhizosphere of walnut (Juglans regia L.); (iii) Azarbaijan, Tabriz, Shahid Madani University Campus (37°48′39″N, 45°56′00″E, altitude 1338 m a.s.l.), in the rhizosphere of white mulberry (Morus alba L.); and (iv) Azarshahr, Gugan, Firooz Salar (37°47′47″N, 45°56′10.2″E, altitude 1340 m a.s.l.), in the rhizosphere of silver berry (E. angustifolia).

Remarks

Some inter-population variations were noted in the Iranian specimens of A. simplex. Thus, females from Azarbaijan Shahid Madani University Campus show a narrower (17.5–19 vs. 20–23 μm) but more expanded lip region, a shorter odontostyle (15–17 vs. 18–22 μm) and odontophore (27–29 vs. 34–38 μm) and a comparatively longer tail (c = 31–35 vs. c = 39–67, c′ = 1.3–1.5 vs. c′ = 0.7–1.2) than those of other populations, and the Mamaghan population has a less convex and somewhat shorter tail. These intraspecific variations, together with those observed in the D2–D3 sequences, are probably due to the influence of environmental conditions. Nevertheless, all of them fit well those previously known in the populations from the USA and Spain (Álvarez-Ortega et al., Reference Álvarez-Ortega, Subbotin and Peña-Santiago2013), with very similar morphology and either totally coincident or widely overlapping morphometrics. The molecular analyses also confirm the identity of the Iranian specimens.

The finding of A. simplex in Iran is a remarkable biogeographical novelty, as it represents the first Asian record of the species, which significantly extends its spread since it was previously known to occur in Jamaica (Thorne & Swanger, Reference Thorne and Swanger1936; Andrássy, Reference Andrássy2001), the USA (Thorne & Swanger, Reference Thorne and Swanger1936; Loof & Coomans, Reference Loof and Coomans1970; Tjepkema et al., Reference Tjepkema, Ferris and Ferris1971; Baird & Bernard, Reference Baird and Bernard1984; Andrássy, Reference Andrássy2001; Álvarez-Ortega & Peña-Santiago, Reference Álvarez-Ortega and Peña-Santiago2010; Álvarez-Ortega et al., Reference Álvarez-Ortega, Subbotin and Peña-Santiago2013) and several European countries – namely, Austria (Zolda, Reference Zolda2002), Bulgaria (Ilieva et al., Reference Ilieva, Iliev and Georgieva2017), France (Loof & Coomans, Reference Loof and Coomans1970; Domowska, Reference Domowska2000; Andrássy, Reference Andrássy2001), Italy (Loof & Coomans, Reference Loof and Coomans1970; Andrássy, Reference Andrássy2001), the Netherlands (Loof & Coomans, Reference Loof and Coomans1970; Bongers, Reference Bongers1988; Andrássy, Reference Andrássy2001), Poland (Winizewska-Slipinska, Reference Winizewska-Slipinska1987), Spain (Álvarez-Ortega et al., Reference Álvarez-Ortega, Subbotin and Peña-Santiago2013) and ?Switzerland (Altherr, Reference Altherr1950, Reference Altherr1952). Thus, the species certainly is a typical representative of the Holarctic nematode fauna.