Enchodelus babakicus, Pedram & Niknam & Guerrero & Ye & Robbins, 2009

Pedram, Majid, Niknam, Gholamreza, Guerrero, Pablo, Ye, Weimin & Robbins, Robert T., 2009, Morphological and molecular characterisation of Enchodelus babakicus n. sp. and E. macrodorus Thorne, 1939 (Nematoda: Nordiidae) from Iran, Nematology 11 (6), pp. 895-907 : 896-902

Enchodelus babakicus * n. sp.

( Figs 1-4 )

MEASUREMENTS

See Table 1.

DESCRIPTION

Female

Moderately slender nematodes of medium size, 1.21- 1.56 mm long. Habitus slightly curved ventrad when heat relaxed, adopting an open C-shape. Body cylindrical, tapering gradually towards both ends but more so anteriorly. Cuticle two-layered, external layer ca 1.0-2.0 µ m thick along entire body, internal layer 2.0-3.0 µ m thick in anterior region, 1.0-1.5 µ m at mid-body and 5.0-7.0 µ m on tail. Cuticle with fine but distinct transverse striations, especially visible at neck and tail regions. Lateral cords granular, forming 15-20% of body diam. at mid-body. Lip region rounded, clearly separated from adjacent body by a distinct constriction, 2.4 times as broad as high or ca one-third of body diam. at neck base. Lips amalgamated, labial and cephalic papillae scarcely projecting above lip contour. Amphidial fovea stirrup shaped, aperture slitlike, located at level of labial constriction, occupying 57- 67% of lip diam. Cheilostom cylindrical, with distinct indentation resembling an additional guiding ring, as described by Coomans (1985) in species of Californidorus and Enchodelus . Odontostyle 2.24-2.34 lip diam. long, well sclerotised with furcate base, 2.5-3.0 µ m in diam. or 13.6-15.3 times as long as broad, guiding ring double, located at 26-30 µ m or 1.3-1.6 lip diam. from anterior end. More or less spherical cavity with weakly sclerotised walls observed just posterior to guiding ring. Odontophore flanged, 1.0-1.2 times longer than odontostyle. Nerve ring located 130-143 µ m from anterior end. Pharynx composed of slender but muscular anterior portion and a muscular expanded part occupying 35.5-38.5% of total neck length, pharyngeal gland nuclei located as follows: DN = 69.0 ± 1.5 (67-72); S 1 N 1 and S 1 N 2 not observed; S 2 N 1 = 54.8 ± 1.0 (53-56); S 2 N 2 = 56.0 ± 1.9 (53-58). Very delicate membrane surrounding pharyngeal expansion. In some specimens, this structure apparently extending along ventral and/or dorsal side of pharyngeal expansion. Cardia hemispherical, about as broad as long, 12-13 × 11-13 µ m in size. Reproductive system amphididelphic, both branches equally developed. Ovaries reflexed, short, not reaching sphincter level, measuring 39- 63 µ m long, oocytes first in two or more rows, then in one row, distal part of ovary consisting of a well developed blind sac, similar to that described by Coomans (1964) in Discolaimus and Longidorus species. Oviduct joining ovary subterminally, close to proximal end of blind sac. Oviduct consisting of tubular part and well developed pars dilatata. Distinct sphincter visible between oviduct and uterus. Uterus 130-175 µ m or 1.9-2.5 body diam. long, tripartite, consisting of a distal spheroid pars dilatata, a slender intermediate portion and a wider proximal part, these three regions generally showing only weak development and obscured in some individuals by intestinal contents. Vagina extending inwards 51-60% of corresponding body diam. Pars proximalis vaginae 21.5 × 23.5 µ m, pars refringens composed of two trapezoidal, well sclerotised, pieces with a combined width of 16.5 × 4.0 µ m, pars distalis vaginae 6.3 µ m long (holotype). Sperm not observed in female genital tract. Prerectum 4.5-8.5 times and rectum 0.9-1.6 anal body diam. long. Tail short, rounded conoid, small saccate bodies observed along ventral surface, cuticle at terminus forming 42-57% of total tail length, two pairs of caudal pores located at middle of tail, one subdorsal, the other lateral.

Male

General morphology similar to that of female except for posterior region curved more ventrad. Reproductive system composed of two testes, anterior 179-262 and posterior 167-257 µ m long. Sperms ellipsoid, measuring 8.0-9.5 × 3.5 µ m. Spicules dorylaimoid, 1.3-1.8 anal diam. long and 3.9-4.8 times longer than wide, lateral accessory pieces paired, more or less cylindrical with bifurcate end, measuring 10.5-12.0×2.5 µ m. Series of 10-14 spaced ventromedian supplements starting 24- 32 µ m from adcloacal pair with posteriormost supplement located within range of retracted spicules, adcloacal pair located at 7.0-11.5 µ m from cloacal opening. Tail short conoid, dorsally convex, slightly ventrally concave with bluntly rounded terminus. Cuticle along ventral surface lacking saccate bodies.

M. Pedram et al.

Juveniles

Body length gradually increasing with stage. Comparison of length of functional odontostyle and replacement odontostyle identified four juvenile stages. Lip region in J1 flat, in J2 offset by a less marked constriction than in J3, J4 and adults. Lip region becoming progressively broader from J1 to J4. Genital primordium at vulval region observed in some J4. Tail in J1 conical, relatively much longer than in subsequent stages (cļ = 3), tail in J2- J4 similar in shape to that of female although becoming relatively shorter with stage (cļ = 1.0, 0.6-0.9 and 0.5-0.7 in J2, J3 and J4, respectively).

TYPE MATERIAL

Holotype female, ten paratype females, ten paratype males and paratype juveniles deposited in the Nematode Collection of the Faculty of Agriculture, University of Tabriz, Tabriz, Iran; two paratype females and two paratype males in separate slides deposited at CABI UK-

Centre, Surrey, UK, and USDA Nematode Collection, Beltsville , MD, USA.

TYPE HABITAT AND LOCALITY

Rhizosphere of grasses from natural grasslands , Kaleibar City, mountains of Babak Fort , north-west Iran.

DIAGNOSIS AND RELATIONSHIPS

The new species is characterised by its 1.21-1.56 mm body length, lip region offset by marked constriction and 17.0-19.0 µ m broad, odontostyle 40-45 µ m long, odontophore flanged and 37-51 µ m long, neck region 283- 413 µ m long, pharyngeal expansion 100-136 µ m long or 35.5-38.5% of total neck length, amphididelphic female genital system, tripartite uterus, vulva pre-equatorial (V = 44-49), tail short, rounded (16-22 µ m long, c = 61- 93, cļ = 0.5- 0.7 in female; 19-30 µ m long, c = 49-72, cļ = 0.5- 0.9 in male), male as frequent as female with 49-61 µ m long spicules and 10-14 spaced ventromedian supplements, the posteriormost of which being within the range of the retracted spicules.

Because of the morphology of the tail and the odontostyle length, E. babakicus n. sp. can be classified un- der the E. macrodorus -group as defined by Guerrero et al. (2008a). This group is characterised by the presence of a rather long odontostyle (> 35 µ m), odontophore with well developed flanges, tripartite uterus and rounded tail, and comprises the species described above together with E. distinctus Ahmad & Jairajpuri, 1980 , E. groenlandicus (Ditlevsen, 1927) Thorne, 1939 , E. macrodorus (de Man, 1880) Thorne, 1939 , E. microdoroides Baqri & Jairajpuri, 1974 and E. saxifragae Popovici, 1995 .

In having a lip region offset by a strong constriction, the new species can be distinguished from E. groenlandicus , E. macrodorus and E. microdoroides . Furthermore, it can be separated from E. groenlandicus by its shorter female body (1.21-1.56 vs 1.57-2.50 mm), shorter odontostyle, odontophore and total stylet (40-45, 37-51 and 79-95 µ m, respectively, vs 44-53, 45-55 and 94-108 µ m), shorter and less developed uterus and frequent presence of males vs absence; from E. macrodorus , probably the closest relative, apart from the deep constriction at the lip region, the new species differs by its slightly more posteriorly located vulva (V = 44-49 vs 37-47), slightly longer uterus (130-175 vs 56-143 µ m or 1.9-2.5 vs 0.9-2.0 body diam.), female tail more conoid (vs almost hemispherical) and greater number of ventromedian supplements (10-14 vs 6-12); and from E. microdoroides by its slightly longer female body (1.21-1.56 vs 0.9-1.3 mm), broader lip region (17.0-19.0 vs 13.0-14.0 µ m), guiding ring located more anterior (26-30 vs 37-39 µ m from anterior end) and males with longer spicules (49-61 vs 45-50 µ m).

The new species resembles the remaining two species, namely E. distinctus and E. saxifragae , in having the lip region offset by a deep constriction. However, it can be distinguished from E. distinctus by its shorter female body (1.21-1.56 vs 1.85 mm), longer odontostyle (40-45 vs 36 µ m), pre-equatorial vulva (V = 44-49 vs 53) and males frequent vs absent. Finally, the new species differs from E. saxifragae by the much shorter female body length (1.21-1.56 vs 1.80-2.38 mm), female genital system with less developed uterus, differently shaped pars refringens vaginae (trapezoidal vs arcuate drop-shaped), shorter tail (16-22 vs 22-40 µ m) and males with slightly shorter spicules (49-61 vs 56-70 µ m) and fewer ventromedian supplements (10-14 vs 13-16).

In the key provided by Guerrero et al. (2008), E. babakicus n. sp. can either be keyed out together with E. microdoroides in step 1, due to the small size of some individuals, or with E. saxifragae in step 3. However, it can be easily distinguished from both by the characteristics listed above.

Figures

Fig. 1. Enchodelus babakicus n. sp. A-C: Female (holotype). A: Anterior end; B: Vagina; C: Tail. D-F: Male. D: Anterior end; E: Guiding system; F: Posterior end; G, H: Entire body of male and female; I: Female tail variation.

Fig. 2. Enchodelus babakicus n. sp. Juveniles. A-D: Anterior end of J1-J4; E-G: Primordium of J2-J4; H-K: Tails of J1-J4, respectively.

Fig. 3. Enchodelus babakicus n. sp. A, C-F: Female holotype. A: Entire body; C: Anterior end; D: Lip region in detail; E: Anterior genital branch; F: Tail. B, G, H: Male. B: Entire body; G: Neck region; H: Posterior end.

Fig. 4. Enchodelus babakicus n. sp. Paratype female. A: Uterus; B: Delicate membrane (arrows) surrounding pharyngeal expansion.