Paracrobeles deserticola, Abolafia, Joaquín, Divsalar, Nafiseh, Panahi, Hadi & Shokoohi, Ebrahim, 2014

Abolafia, Joaquín, Divsalar, Nafiseh, Panahi, Hadi & Shokoohi, Ebrahim, 2014, Description of Paracrobeles deserticola sp. n. and Nothacrobeles hebetocaudatus sp. n. (Nematoda: Rhabditida: Cephalobidae) from Iran and the phylogenetic relationships of these two species, Zootaxa 3827 (1), pp. 1-19 : 4-10

Paracrobeles deserticola sp. n.

( Figs 1–3 )

Measurements. See deserticola .

Description. Adult: Body 0.48–0.66 mm long, with habitus somewhat curved ventrad after fixation. Cuticle deeply annulated and weakly tessellated, especially in anterior end, into rectangular blocks with striae discontinuous across annulations, with two rows of punctations in each annuli at anterior end of body. Lateral field with two wings, areolated, separated by a narrow groove, appearing as four longitudinal incisures under LM, occupying 13–16% of midbody diameter, extending posteriorly to phasmid. Lip region slightly offset from the neck, bearing six labial and four cephalic papillae. Amphid openings clearly visible, large and ovoid, about 17–20% of the labial region diameter. Three pairs of asymmetrical lips, one dorsal and two ventrolateral, with two long seta-like processes arising from margin; primary axils deep, U-shaped, bearing one triangular-elongate guard process originating from the incomplete first annulus; secondary axils with two setiform guard processes with one originating from each lip. Oral opening surrounded by three labial probolae, connected at bases by tangential ridges; each labial probola with a short basal part and a distal longer and bifurcated part, with prongs very long and divergent, straight, lacking lateral tines and secondary bifurcations; the base of the bifurcation is slightly expanded toward the secondary axil. Stoma cephaloboid; cheilostom with well developed oval rhabdia, gymnostom very short, and stegostom with minute rhabdia. Pharynx cephaloboid; pharyngeal corpus 1.7–3.2 times isthmus length, with cylindrical procorpus; elongate and dilated metacorpus with expanded lumen and sclerotized walls; pharyngeal corpus-isthmus junction slightly swollen; isthmus slender, demarcated by a break in muscular tissue; basal bulb ovoid, with valvular apparatus. Cardia conoid, surrounded by intestinal tissue. Nerve ring at 57–64% of neck length, at level of isthmus. Excretory pore at 56–66% of neck length, at level of isthmus, 24–26 annuli from anterior end. Deirids at 66–82% of neck length, at level of isthmus, 28–31 annuli from anterior end. Intestine without distinct specializations, but having anterior and posterior extremes with thinner walls.

Female: Reproductive system monodelphic-prodelphic, in a dextral position in relation to intestine. Ovary short, not reaching the distal part of postvulval sac, without flexures. Oviduct short. Spermatheca well developed, 1.1–1.5 times as long as the corresponding body diameter. Uterus tubular, 1.7–2.0 times as long as the corresponding body diameter. Post-uterine sac well developed, 2.9–4.5 times body diameter long, differentiated in two regions, one proximal tubular and other distal scarcely swollen. Vagina sunken, extending inwards 0.2–0.4 times body diameter, continued with a uterine tube connecting uterus and post-uterine sac. Vulval lips not protruding. In length, rectum 0.6–1.1 times anal body diameter; three large gland-like cells are distinguishable around the intestine-rectum junction. Tail conical with finely rounded terminus, having 15–17 ventral annuli. Phasmid located at 34–44% of tail length.

Male: General morphology similar to female. Reproductive system monorchic, dextral in position, with testis reflexed ventrad anteriorly. Spicules paired and symmetrical, very slender and curved ventrad, with more or less rounded manubrium, conoid calamus, and ventrad curved lamina with acute tip. Gubernaculum well developed, with a curve in its middle part, 16–24 mm long or about 32–47% of the spicules length. Three large gland-like cells are distinguishable around the beginning of the cloaca. Three pairs of precloacal genital papillae were observed: first pair 65–72 µm, second pair 34–39 µm and third pair 3–4 µm anterior to the cloacal aperture. Five pairs of caudal genital papillae are present along the tail, comprising one subventral pair, one lateral pair and three pairs near tail terminus. Tail conoid and curved ventrad with finely rounded tip. Phasmids located at 36–43% of tail length.

Diagnosis. The new species is characterized by its body length (0.48–0.60 mm in females and 0.47–0.66 mm in males), cuticle annulated and weakly tessellated into longitudinal blocks with striae discontinuous across annulations, lateral field with two wings, areolated, separated by a narrow groove, lip region slightly offset, 15–20 Μm wide, lips asymmetrical with two long seta-like processes along its margin, primary axils bearing one triangular-elongate guard process, secondary axils with two setiform guard processes with one originating from each lip, labial probolae bifurcated with long and smooth prongs having a small basal ridge, stoma 11–14 Μm long, metacorpus swollen, spermatheca 33–50 Μm long, post-uterine sac 60–96 Μm long or 2.9–4.5 times the corresponding body diameter, vulva located slightly posterior to middle of body (V = 50–63), female tail conical with finely rounded tip (53–67 Μm, c = 9.0–10.0, c’ = 2.0–3.0), male tail conical and curved ventrad with finely rounded tip (48–54 Μm, c = 9.0–13.0, c’ = 1.8–2.0), spicules 46–56 Μm long and curved ventrad, and gubernaculum 16–24 Μm long.

Relationships. The new species, P. deserticola sp. n., shows similarities to P. psammophilus Navarro and Lluch, 1999 , but it differs in having a slightly longer body (L=480–602 µm vs L=360–552 µm in females and L=467–657 µm vs L=424–531 µm in males), lips with two long tines (vs with three long tines, according SEM observations by Orselli & Vinciguerra, 2002), nerve ring in a more anterior position (at isthmus close to pharyngeal corpus junction vs at middle part of isthmus), post-uterine sac scarcely swollen (vs very swollen), female tail slightly longer (53–67 µm vs 46–53 µm), spicules slightly angular (vs not angular), and shorter gubernaculum (16–24 µm vs 20–39 µm). The new species differs from the specimens studied by Orselli and Vinciguerra (2002) in having a shorter pharynx (144–178 µm vs 192–212 µm in females and 159–174 µm vs 184–232 µm in males), longer ovary (about 2.5 times longer than the corresponding body diameter vs about as long as the body diameter), slightly longer spermatheca (33–50 µm vs 30–37 µm), shorter male tail (48–54 µm vs 56–70 µm), shorter spicules (46–56 µm vs 68–81 µm), and shorter gubernaculum (16–24 µm vs 28–31 µm).

In addition, the new species also has similarities to P. laterellus Heyns, 1968 and P. mojavicus Taylor, Baldwin & Mundo-Ocampo, 2004 . However, the very different morphology of the spicules (thinner and more than 40 µm vs thicker and shorter than 40 µm) distinguish these species.

range).

P. deserticola sp. n. N. hebetocaudatus sp. n.

Locality Kerman Kerman

Province Kerman Kerman

Habitat White saxaul White saxaul

Holotype Paratypes Paratypes Holotype Paratypes Paratypes ♀ 7 ♀♀ 8 ♂♂ ♀ 9 ♀♀ 8 ♂♂

length 566 548.8±52.1 (480–602) 562.5±53.9 (467–657) 425 465.0±31.7 (420–513) 444.2±30.6 (420–518) 16.8 16.2±1.8 (14–18) 17.0±1.8 (13.0–19.0) 18.4 17.8±1.8 (15.1–19.9) 20.6±2.1 (17.2–23.1) 3.4 3.4±0.3 (3.0–4.0) 3.4±0.3 (3.0–4.0) 3.6 3.7±0.2 (3.4–4.1) 3.7±0.1 (3.6–3.8) 8.9 9.4±0.5 (9–10) 11.2±1.2 (9.0–13.0) 13.3 14.1±0.6 (13.6–15.5) 13.4±1.1 (11.5–15.3) 3.2 2.7±0.3 (2.0–3.0) 2.0±0.1 (1.8–2.0) 2.3 2.0±0.2 (1.8–2.3) 1.8±0.1 (1.7–2.0) 60 58.0±3.9 (50–63) – 64 65.7±3.4 (62–74) –

Labial probolae 15 14.9±0.8 (14–16) 15.7±0.7 (15–16) 9 8.8±1.1 (8–11) 8.7±2.0 (7–11)

region width 20 16.6±1.0 (16–20) 18.1±1.5 (15–19) 11 11.7±0.9 (11–13) 11.4±1.0 (10–13)

Stoma 14 12.2±1.4 (11–14) 12.4±0.9 (12–14) 10 10.4±0.4 (10–11) 10.0±1.9 (8–13)

Pharyngeal corpus 91 95.8±4.3 (89–104) 95.3±2.6 (92–100) 70 71.0±4.8 (64–76) 70.5±3.5 (68–76)

Isthmus 36 38.3±8.0 (30–53) 34.1±2.1 (30–36) 19 24.2±4.8 (20–32) 19.2±4.4 (15–25) 28 27.8±1.6 (26–31) 27.6±1.8 (25–30) 18 20.8±1.4 (20–24) 18.5±2.4 (15–22)

Pharynx length 166 162.1±11.0 (144–178) 166.6±6.6 (159–174) 107 115.9±4.8 (111–124) 110.7±8.9 (99–124)

length* 179 174.3±11.5 (156–192) 179.0±6.6 (171–188) 117 126.9±4.1 (122–135) 118.5±7.6 (112–136)

Nerve ring - ant. end 114 107.3±6.0 (97–115) 115.5±5.7 (106–123) 84 86.7±5.3 (81–93) 87.0±6.0 (82–96)

Excretory pore - ant. end 107 103.3 ± 7.2 (96–111) 109.5±7.5 (101–120) 93 90.7±6.7 (83–101) 91.4±6.9 (85–100)

Deirid - ant. end 122 126.7±3.1 (124–130) 132 (n= 1) 100 108.0±0.2 (106–110) 105.3±5.5 (100–111)

Cuticle thickness 2.5 2.5 ± 0.3 (2.0–3.0) 2.3±0.3 (2.0–3.0) 1.5 2.0±0.0 (2.0) 1.8±0.3 (1.5–2.0)

Annuli width 3.8 3.9 ± 0.5 (3.0–4.0) 4.0±0.5 (3.0–5.0) 2 2.6±0.3 (2.5–3.0) 2.6±0.2 (2.5–3.0)

width: neck base 32 33.7 ± 2.5 (32–39) 32.7±1.0 (31–34) 24 24.4±1.5 (23–26) 21.3±2.3 (19–25) midbody 34 34.0 ± 2.3 (33–39) 33.2±1.4 (31–36) 23 26.4±3.1 (22–30) 21.8±2.9 (19–26) anus 20 21.5 ± 1.2 (20–23) 25.6±1.1 (24–27) 14 16.4±1.3 (14–18) 18.6±2.3 (16–23)

Ovary 131 106.1 ± 11.5 (89–132) – 164 150.4±35.3 (107–198) –

Spermatheca 40 40.0 ± 7.1 (33–50) – 24 44.1±10.3 (26–55) –

Vagina 10 8.7 ± 2.5 (6–13) – 6 7.8±2.3 (6–12) –

Post-uterine sac 90 75.4 ± 12.6 (60–96) – 18 22.9±2.9 (20–27) –

Vulva - anterior end 342 317.3±25.7 (289–355) – 273 305.4±26.2 (266–339) –

Rectum 23 16.8 ± 3.7 (13–23) – 14 16.4±2.8 (12–21) –

64 58.6±4.5 (53–67) 50.2±2.5 (48–54) 32 32.5±2.2 (30–36) 33.4±4.1 (28–40)

Phasmid - anus distance 27 21.9 ± 2.4 (19 –28) 19.2±1.4 (18–21) 15 18.2±1.0 (17-19) 18.6±2.3 (16-23)

Spicules - – 50.5±3.6 (46–56) – – 21.7±1.5 (20–25)

Gubernaculum - – 20.5±2.6 (16–24) – – 12.9±1.7 (11–16)

Stoma + pharynx

This is the first record of the genus from Iran.

Type locality and habitat. The specimens were collected in a desert area close to Kerman (province of Kerman, Iran; N: 30°15'11"; E: 57°06'11"; date of sampling: 2013), associated with the rhizosphere of Haloxylon persicum L.

Type material. Female holotype, seven female and five male paratypes deposited in the nematode collection of the Department of Plant Protection, College of Agriculture, Shahid Bahonar University of Kerman, Iran. Five female paratypes and three male paratypes deposited in Departamento de Biología Animal, Biología Vegetal y Ecología, Universidad de Jaén, Spain.

Etymology. The specific name of this species refers to the habitat where it was found.

Figures

FIGURE 1. Paracrobeles deserticola sp. n. A: Neck. B: Lip region. C: Female reproductive system. D: Entire female. E: Entire male. F: Lateral field. G: Male posterior end. H: Female posterior end.

FIGURE 2. Paracrobeles deserticola sp. n. (LM). A: Neck. B – D: Lip region in lateral, ventral and subventral views, respectively (I: primary axil, II: secondary axil, black arrows point to axillar guarding processes, white arrows point to labial setae-like processes and asterisk indicates the amphid). E: Female reproductive system. F: Lateral field at neck level. G: Female posterior end. H: Male posterior end.

FIGURE 3. Paracrobeles deserticola sp. n. (SEM). A-E: Lip region in ventral, right subventral, right sublateral, right lateral and frontal views, respectively. F, I, H: Male posterior end (white arrows point to genital papillae, black arrow points to phasmid). G: Lateral field.