Cephaloboides curvicaudatus ( Schneider, 1866 ) Zullini, 1982

Tahseen, Qudsia, Hussain, Ather, Ahlawat, Shikha, Mustaqim, Malka & Khan, Zakaullah, 2017, Description of a new and two known species of Cephaloboides Rahm, 1928 (Nematoda: Rhabditidae) from India, with discussion on the taxonomy of the genus, Zootaxa 4277 (3), pp. 352-368 : 358-361

Cephaloboides curvicaudatus ( Schneider, 1866) Zullini, 1982

( Figs. 3 , 4 )

= Rhabditis brevispina apud Hofmänner (1913) , nec Anguillula brevispina Claus, 1862

= Rhabditis macrospiculata Stefański, 1916

= Rhabditis micoletzkyi Schneider, 1923

= Rhabditis producta apud Skrjabin, Shikhobalova, Sobolev, Paramonov & Sudarikov (1954) , nec Leptodera producta Schneider, 1866

= Rhabditis insulana Ditlevsen, 1971

= Odontorhabditis musicola Timm, 1959 syn. n.

= Flagicaudoides pawani Khan, Singh & Baird, 1999 syn. n.

Measurements. Table 1.

Description. Adult: Body 0.9–1.2 mm long, slender, almost straight or slightly ventrally curved upon fixation. Cuticle double, about 2.5–3.0 µm thick with fine transverse and longitudinal striations. Lateral fields indistinct. Lip region offset from adjoining body. Lips prominent, globular with smooth margins, amalgamated. Lips provided with inner labial sensilla close to oral aperture; cephalic and outer labial sensilla slightly raised and towards outer border of lips. Amphids small, on lateral lips, not easily discernible under LM. Stoma tubular, 3–4 times longer than wide or slightly longer than lip diameter. Cheilostom not cuticularized, with diverging walls. Gymnostom arched, thickly cuticularized about 1/4th of stomal length. Stegostom surrounded by pharyngeal collar, covering more than 50% of stoma. Each metastegostomal swelling bearing a minute wart. Metastegostom isotopic and isomorphic. Pharynx comprising of 127–155 µm long, swollen corpus; 60–88 µm long isthmus and a massive, ovoid, basal bulb of 40–55 µm x 35 –53 µm dimension with a grinder and two-chambered haustrulum. Nerve ring encircling isthmus about 68–79% of neck length from anterior end. Secretory-excretory pore slightly posteriorly placed, at 71–85% of pharyngeal length; mostly obscure with indistinct duct. Body at proximal end of pharynx about 2.5–4.0 times wider than lip diameter and that at distal end about 4 times wider. Anterior part of pharynx 1.0–1.3 times longer than the posterior part. Cardia 7–11 µm long, flattened. Intestine granular with wide lumen. Rectum thin-walled, less than anal body diameter long. Rectal glands obscure. Anus a crescent-shaped slit.

Female: Reproductive system didelphic, amphidelphic. Ovaries dorsally reflexed; anterior ovary on left side and posterior on right side of intestine. Oocytes at distal end arranged in two rows followed by a single row. Oviduct dilated proximally leading to an elongated spermatheca. Prominent sphincter present at junction of spermatheca and collumella. Latter provided with glandular cells. Uterus with 1– 8 eggs of 45– 51 x 29 –35 µm dimension in late embryonic stages. Some females showed hatched juveniles inside their bodies. Vagina thinwalled, 15–25 µm long, at right angle to longitudinal body axis, supported with muscles. Vaginal lumen with distal folds appearing as internal epiptygma. Vulva a post-equatorial transverse slit, located at 525–680 µm with slightly protruded and fringed lips, often bounded by small vulval flaps. Vulva-anus distance 358–509 µm. Tail cupolashaped with a long, fine spike, about 4.0–4.5 anal body diameters long. Phasmids opening at beginning of tail spike.

Male: Similar to female in general morphology except being smaller in size and more arcuate ventrally. Testis single, ventrally reflexed, at right side of intestine. Reflexed part about 115–193 µm long. Spicules strongly cuticularized, slightly arcuate, with elongate capitula having striated outline. Each spicule cylindroid with a swollen distal end, provided with a narrow dorsal thorn reaching up to its length and a ventral triangular process at 1/3rd of its length. Protruding spicules observed with an extended gelatinous cap; gubernaculum with arcuate conical proximal end and a wide distal end and curving a little around sides. Bursa leptoderan, anteriorly open, weakly developed. Genital papillae nine pairs in 1+2/1+3+2+P configuration with three precloacal and six postcloacal pairs. GP1 subventral close to grouped GP2, GP3; GP4 lateral, protruding outside bursal margin; GP5, GP6, GP7 subventral forming a group; GP8 subdorsal, protruding outside bursal margin; GP9 close to GP8, subventral. Phasmidial ducts smaller and slenderer than genital papillae opening next to GP9. Copulatory muscles well developed with 7–8 paired bands starting at cloacal level.

Locality and habitat. Samples containing Cephaloboides curvicaudatus were obtained from ditch near Ghana Canal at Keoladeo National Park , Bharatpur , Rajasthan, India at coordinates 27.1593° N, 77.5232° E.

Voucher specimens. Nine females and eight males on slide Cephaloboides curvicaudatus KNP 15 A/ 1–7 deposited in the Nematode Collection of Department of Zoology , Aligarh Muslim University, Aligarh, India.

Emended diagnosis. Cephaloboides curvicaudatus is characterized by large-sized body; double, finely striated, cuticle with faint longitudinal lines; slightly raised labial papillae; long stoma with a denticle on each metastegostomal plate; long spicate tail of 4.0–4.5 anal body diameter length; long, cylindroid spicules with elongate capitula and swollen distal ends with an extended gelatinous cap; genital papillae in 1+2/1+3+2+P configuration and 7–8 paired bands of copulatory muscles.

Remarks. The present population shows conformity to C. curvicaudatus in most characteristics except few minor ones: relatively smaller b value and presence of strong copulatory muscle bands (b =3.8–4.5 vs 3.4–6.0 and copulatory muscle bands not reported in C. curvicaudatus ). The present population further differs from C. curvicaudatus in having spicules with elongate capitula.

Figures

FIGURE 3. Cephaloboides curvicaudatus (Schneider, 1866) Zullini, 1982. A: Entire female. B: Entire male. C: Female anterior end. D: Female pharyngeal region. E: Female anterior genital branch. F: Female posterior region. G – I: Male posterior region. J: Spicule and gubernaculum.

FIGURE 4. Cephaloboides curvicaudatus (Schneider, 1866) Zullini, 1982. A: Anterior end (scanning electron microscopy). B – D: Anterior end. E: Anterior pharyngeal region. F: Posterior pharyngeal region. G: Vulval region. H: Body region showing lateral fields. I: Female posterior end. J, K: Male posterior region (lateral). L, M: Male posterior region (ventral). N: Spicule (Scale bars = 10 µm).