Nothacrobeles hebetocaudatus, 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 : 10-15

Nothacrobeles hebetocaudatus sp. n.

( Figs 4–6 )

Measurements. See Table 2.

Description. Adult: Body 0.42–0.52 mm long, with habitus somewhat curved ventrad after fixation. Cuticle “single”. Annuli well developed and divided in blocks, but with LM these are not clear in all specimens, and with two rows of punctations also not clearly visible under LM. Lateral field with three longitudinal incisures or two wings (sometimes both wings are slightly separated appearing as four incisures), occupying 17–22% of midbody diameter, becoming less distinct towards tail terminus. Lip region offset from the neck, bearing six labial and four cephalic papillae. Amphid openings circular. Three pairs of asymmetrical lips, one dorsal and two ventrolateral; primary axils deep, U-shaped, bearing one triangular-elongate guard process originating from the incomplete first annulus; secondary axils demarcated by narrow incisures separating the lips of the pair, without guard processes. Each lip asymmetrically rectangular, divided in two sections at level of the labial papilla. Each lip with four tines along its margin: one long tine facing the primary axil, one short facing the secondary axil, and two of intermediate size between. Oral opening surrounded by three labial probolae, connected at bases by tangential ridges; each labial probola with short basal part, and a distal part longer and bifurcated, with divergent prongs, straight, more curved at tips, lacking lateral tines and secondary bifurcations; the base of the two prongs is expanded to form a smooth basal ridge, protruding toward the secondary axil, rounded in lateral view. Stoma cephaloboid; cheilostom with well-developed oval rhabdia, gymnostom very short, and stegostom with minute rhabdia. Pharynx cephaloboid; pharyngeal corpus cylindrical-fusiform, 2.0–3.7 times isthmus length; pharyngeal corpus-isthmus junction not swollen; isthmus slender, demarcated by a break in muscular tissue; basal bulb ovoid to spheroid, with valvular apparatus. Cardia conoid, surrounded by intestinal tissue. Nerve ring at 60–70% of neck length, at level of metacorpus-isthmus junction. Excretory pore at 70–72% of neck length, at level of isthmus, close to hemizonid although not too much clear, 28–38 annuli from anterior end. Deirids at 73–78% of neck length, at level of isthmus or isthmus-bulb junction, 35–40 annuli from anterior end. Intestine without distinct specializations, although cardiac region has thinner walls.

Female: Reproductive system monodelphic-prodelphic, in a dextral position in relation to intestine. Ovary with a row of oocytes, lacking flexures. Oviduct short. Spermatheca well developed, 1.1–2.2 times as long as the corresponding body diameter. Uterus 2.9–3.8 times as long as the corresponding body diameter. Post-uterine sac well developed, 0.7–1.3 times body diameter in length. Vagina extending inwards 0.3–0.4 times body diameter. Vulval lips not protruding. Rectum 0.5–0.8 times anal body diameter in extent; three large gland-like cells present around the intestine-rectum junction. Tail conical with rounded terminus, having 15–17 ventral annuli. Phasmid located at 38–44% of tail length.

Male: General morphology similar to female. Reproductive system monorchic, dextral in position, with testis reflexed ventrad anteriorly. Spicules paired and symmetrical, curved ventrad with more or less conoid manubrium, conoid calamus, ventrad curved lamina, both poorly developed proximal dorsal hump and velum at ventral side. Gubernaculum thin, slightly curved ventrad. Three large gland-like cells are distinguishable around the beginning of the cloaca. Three pairs of precloacal subventral genital papillae. Five pairs of caudal genital papillae arranged as follows: two pairs at mid-tail, one subventral and one lateral close to the phasmid; and three pairs in the posterior part of the tail, one subventral, one lateral and one subdorsal; a single midventral papilla is located anterior to the anterior lip of the cloaca. Tail conoid and curved ventrad, especially in its distal part, with rounded terminus. Phasmids located at 44–50% of tail length.

Diagnosis. The species is characterized by its body length (0.42–0.51 Μm in females and 0.42–0.52 µm in males), “single” cuticle, lateral field with three incisures, asymmetrical lips divided in two sections at level of the labial papilla, each lip with four tines along its margin, primary axils deep bearing one triangular-elongate guard process originating from the incomplete first annulus, secondary axils demarcated by narrow incisures separating the lips of the pair and without guard processes, labial probolae bifurcated and without tines (7–11 Μm long), pharyngeal corpus 2.0–3.7 times isthmus length, R ex = 28–38, spermatheca 24–55 Μm long or 2.9–3.8 times the corresponding body diameter, post-uterine sac 18–27 Μm long or 0.7–1.3 times the corresponding body diameter long, female tail conical with rounded terminus (30–36 Μm, c = 13.6–15.5, c' = 1.8–2.3), phasmid at 38–44% of tail length, male tail conical (28–40 µm, c = 11.5–15.3, c' = 1.7–2.0), spicules 20–25 µm long and gubernaculum 11–16 µm long.

Relationships. The new species, Nothacrobeles hebetocaudatus sp. n., is very similar with N. abolafiai (see comments below), differentiated from it by having a smaller body size in females (420–518 vs 518–655 Μm), cuticle tessellated in quadrangular blocks (vs rectangular blocks), lateral field in females ending at phasmid (vs ending at tail tip), four acute tines on each lip (vs four rounded plus one long triangular tines), the more anterior position of excretory pore, nerve ring and deirid, length of spermatheca (26–55 µm vs 22–30 µm), more posterior vulva (V = 62–74% vs 57–65%), length of post-uterine sac (20–27 µm vs 15–18 µm), relative length of rectum (0.5–0.8 ABD vs 0.9–1.3 ABD), and number of ventral annuli on female tail (15–17 vs 12–15).

Type locality and habitat. The species was collected in a desert area close to Kerman, along Haft Bagh highway (province of Kerman, Iran; N: 30°14'22.4"; E: 57°06'28.7"), associated with the rhizosphere of Haloxylon persicum L.

Type material. Female holotype, eight 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. Four female paratypes and three male paratypes deposited in Departamento de Biología Animal, Biología Vegetal y Ecología, Universidad de Jaén, Spain. One male paratype used for SEM analysis.

Etymology. The specific name of this species refers to the female tail morphology (latin, hebetus = blunt, caudatus = tail).

Figures

FIGURE 4. Nothacrobeles hebetocaudatus sp. n. A: Neck. B: Lip region. C, D: Female posterior end. E: Entire female. F: Female reproductive system. G: Entire male. H: Male posterior end.

FIGURE 5. Nothacrobeles hebetocaudatus sp. n. (LM). A: Neck. B: Lip region. C, D: Male posterior end at genital papillae and spicules levels, respectively (white arrows point at genital papillae, black arrow points at phasmid). E: Lateral field (arrows point at each longitudinal incisures). F: Vulva (ventral view). G: Female reproductive system at postuterine sac level. H: Female posterior end (white arrow points to phasmid).

FIGURE 6. Nothacrobeles hebetocaudatus sp. n. (SEM). A: Anterior end (arrow points to excretory pore). B, C, D, F, H: Lip region in frontal, subventral, ventral, right lateral, and dorsal views, respectively. E: Male posterior end (arrows point to genital papillae; cuticle blocks have collapsed). G: Lateral field. I, J: Female tail (sublateral and ventral views, respectively; arrows point to the phasmids). A – D, F – J: Juvenile; E: Male (cuticle blocks collapsed during processing).