Allodorylaimus tuccitanus, Peña-Santiago & Cortés, 2023

Peña-Santiago, Reyes & Cortés, Nazareth, 2023, Description of Allodorylaimus tuccitanus sp. nov., with updated taxonomy of the genus (Nematoda: Dorylaimida: Qudsianematidae), Journal of Natural History 57 (5 - 8), pp. 445-462 : 447-454

Allodorylaimus tuccitanus sp. nov.

( Figures 1–3 ; Tables 1 , 2 )

Morphometrics

See Table 1 .

Diagnosis

The new species is characterised by its 1.51–1.69 mm long body, lip region hardly offset by depression or almost continuous and 14.0–15.5 µm wide, odontostyle 13.0–15.5 µm long, neck 321–417 µm long, pharyngeal expansion occupying 43–49% of the total neck length, presence of dorsal cell mass at level of cardia, female genital system diovarian, plicate sphincter, uterus bipartite and 101–207 µm or 2.0–3.6 body diameters long, V = 48–52, tail conical (38–45 µm, c = 34–42, c̾ = 1.4–1.6), spicules 55–59 µm long, and 11 spaced ventromedian supplements without hiatus.

Etymology

The specific epithet is a Latin term referring or belonging to Tucci, the Roman name of Martos town, the capital of the municipality where the new species was collected.

Type locality and habitat

Spain, south-eastern Iberian Peninsula, province of Jaén, at the enclave named ′ Peña de Martos ̍ (37.715ºN, 3.958ºW, elevation up to 1003 m), associated with a plant community whose dominant species are Brachypodium phoenicoides (L.), Stipa bromoides (L.), Astragalus hamosus L., Ballota sp. , Euphorbia exigua L. and Retama sphaerocarpa (L.).

Material examined

Six females and three males, in a good state of preservation.

Table 2. (Continued).

Type material

Deposited at the Nematode Collection of Departamento de Biología Animal, Biología Vegetal y Ecología, University of Jaén, Spain.

Description

Adult. Moderately slender to slender nematodes (a = 28–36) of medium size, 1.51– 1.69 mm long. Body cylindrical, tapering towards both ends, but more so towards the posterior extremity as the caudal region is conical. Upon fixation, habitus curved ventrad, C-shaped in females, J- or G-shaped in males. Cuticle three-layered, consisting of outer and inner thin layers and thicker intermediate layer, especially distinct at caudal region, its total thickness 1.5–2.5 µm in anterior region, 3.0–4.5 µm at midbody, and 4.5–7.5 µm on tail. Lateral chord 13.5–15.5 µm wide, occupying more than one-fourth (25–31%) of maximum body diameter. Body pores indistinct. Lip region hardly offset by a shallow depression, almost continuous, 2.5–3.1 times as wide as high, and ca one-third (31–35%) of body diameter at neck base, with mostly amalgamate and slightly angular lips, and slightly protruding labial and cephalic papillae. Amphid fovea funnel-like, its aperture 7.5–8.5 µm or one-half to three-fifths (50–61%) of lip region diameter. Cheilostom cylindrical, 7.5–9.0 µm long, with visibly incurved, thick walls. Odontostyle length almost equal to lip region diameter, 5.1–7.6 times longer than wide, its aperture one-third to one-half (34–47%) of the total length. Guiding ring simple. Odontophore linear, lacking any differentiation, 1.5–1.8 times as long as odontostyle. Pharynx entirely muscular, gradually enlarging into the pharyngeal expansion that is 6.4–7.8 times as long as wide, 3.5–3.7 times longer than body diameter at neck base, and occupying up to one-half (43–49%) of the total neck length; gland nuclei located as follows: DO = 58–65, DN = 61–68, S1N1 = 72–73, S1N2 = 82–86, S2N = 92–95. Pharyngo-intestinal junction consisting of a conical cardia 15–25 × 8.5–10 µm, enveloped by intestinal tissue, and a weak ring-like structure around its junction with the pharyngeal base. A dorsal cell mass is always present at level of cardias.

Female. Female genital system diovarian, with equally developed genital branches, the anterior 243–276 µm or 15–17% of body length, the posterior 249–333 µm or 16–21%. Ovaries comparatively large, 118–159 µm long. Oviduct 71–155 µm long, with slender distal section made of prismatic cells and large proximal pars dilatata showing lumen inside. A conspicuous sphincter separates oviduct and uterus, and presents a distinct, plicate, inner sclerotisation. Uterus 101–207 µm or 2.0–3.6 body diameters long, bipartite – that is, consisting of a slender distal region with narrow lumen and visibly sclerotised lining, and a wider proximal section with wide lumen that contains abundant sperm cells. Vagina extending inwards 31–37 µm, reaching more than three-fifths (61–70%) of body diameter: pars proximalis 19–25 × 14–20 µm, with sigmoid walls surrounded by moderately developed circular musculature, pars refringens consisting of (in lateral view) two trapezoidal, sclerotised pieces measuring 4–5 × 6.5–7.5 µm and with a combined width of 14.0– 15.5 µm, and pars distalis 4.5–6.0 µm long. Vulva probably transverse, preceded by a depression of body surface. Prerectum 2.8–3.3, rectum 1.3–1.6 anal body diameters long. Tail conical, with finely rounded tip, somewhat curved ventrad, sometimes only appreciable at its posterior end, inner core reaching 71–81% of total length, a hyaline terminal portion 8.5– 12.5 µm long being always present.

Male. Genital system diorchic, with opposite testes. Sperm cells spindle-shaped, 6.0– 6.5 µm long. Prerectum 3.6, cloaca 1.3 times the body diameter at level of cloacal aperture. In addition to the ad-cloacal pair, located at 4–8 µm from the cloacal aperture, there is a series of 11 variably spaced (11–30 µm apart) ventromedian supplements, two of them situated within the range of spicules, and the most posterior at 17–30 µm from the ad-cloacal pair, hence without hiatus. Spicules dorylaimid, 4.6–5.4 times longer than wide, 1.8 times longer than the corresponding body diameter, dorsally regularly convex, ventrally with moderately distinct hump and hollow: head 12.5–17.0 µm long or 23–30% of spicule length, median piece 3.0–4.5 µm wide or 29–37% of maximum spicule width, posterior tip 4.5–6.0 µm wide, curvature 120–125°, hump situated at 29–32% of spicule length from the anterior end. Lateral guiding piece 13–16 × 4.5–5.0 µm. Tail similar to that of female, but somewhat more regularly curved ventrad.

Relationships

The new species is morphometrically similar to A. aljabaranus Quijano et al., 1991 , another Iberian species, but can be distinguished from it by its three-layered (vs bi-layered) cuticle, less differentiated lip region (hardly offset by a weak depression and slightly angular vs offset by a distinct depression and visibly angular), comparatively shorter odontostyle (0.9–1.0 vs 1.2–1.4 times the lip region diameter), bipartite (vs simple) uterus, pars refringens vaginae with different shape (two wider than long trapezoidal pieces vs two longer than wide triangular or drop-shaped pieces), and female tail slightly curved ventrad at its posterior part (vs regularly curved ventrad).

It also resembles A. ferrisorum Andrássy, 1986 and A. tarkoenensis (Andrássy, 1959) Andrássy, 1986 . Nevertheless, it differs from A. ferrisorum , a Holarctic ( USA, Hungary) taxon, in its three-layered (vs bi-layered) cuticle, lip region less offset (vs marked by constriction) and narrower (14.8 ± 0.5 µm vs 17.6 ± 0.7 µm in females and 18.0 ± 0.6 in males), shorter female prerectum (86.7 ± 6.5 vs 109 ± 14 µm), pars refringens vaginae with two (vs four) sclerotised pieces, and fewer (11 vs 15–18) ventromedian supplements. From A. tarkoenensis , at present a Hungarian endemism, it differs in its larger general size (body 1.51–1.69 vs 1.16–1.34 mm long; neck 321–417 vs 283–307 µm), comparatively longer pharyngeal expansion (43–49 vs 37–39% of the total neck length), and much longer spicule (55–59 vs 39 µm).

Figures

Figure 1. Allodorylaimus tuccitanus sp. nov. (a) Female, entire. (b, c) Anterior region in lateral median view. (d) Anterior region in lateral surface view. (e) Pharyngo-intestinal junction. (f) Male, entire. (g) Oviduct-uterus junction. (h) Vagina region. (i) Female, caudal region. (j) Male, posterior body region. (k) Male, caudal region. (l) Female, anterior genital branch. (m) Spicule. Scale bars: a, f = 200 µm; b = 20 µm; c–e, g, i, k, m = 10 µm; h = 5 µm; j, l = 50 µm.

Figure 2. Allodorylaimus tuccitanus sp. nov. (Light Microscpy, ♀). (a–c) Anterior region in lateral median view. (d) Anterior genital branch. (e) Anterior region in lateral surface view. (f) Pharyngointestinal junction. (g) Entire. (h) Oviduct-uterus junction. (i–k) Vagina region. (l–o) Caudal region. Scale bars: a, b, i, l–o = 10 µm; c, j, k = 5 µm; d = 50 µm; g = 200 µm.

Figure 3. Allodorylaimus tuccitanus sp. nov. (Light Microscopy, ♁). (a) Posterior body region. (b) Entire. (c) Caudal region. (d) Spicule. Scale bars: a = 50 µm; b = 200 µm; c, d = 10 µm.