Enchodelus sardashtensis, Pedram & Pourjam & Robbins & Ye & Santiago, 2011

Pedram, Majid, Pourjam, Ebrahim, Robbins, Robert T., Ye, Weimin & Santiago, Reyes Peña-, 2011, Description of one new, and new data on two known, species of Enchodelus Thorne, 1939 (Dorylaimida: Nordiidae) from Iran, Nematology 13 (6), pp. 729-740 : 734-737

Enchodelus sardashtensis * sp. n.

( Figs 2 , 3 )

MATERIAL EXAMINED

Ten females from one location.

MEASUREMENTS

See Table 3. Female

Moderately slender nematodes of medium size, 1.29- 1.50 mm long. Body cylindrical, tapering towards anterior end. Habitus curved ventrad upon fixation, adopting an open C-shape. Cuticle two-layered, 2.0-3.0 µ m thick in anterior region, 1.5-3.0 µ m at mid-body and 4-5 µ m on tail, outer layer bearing very fine transverse striations which are more conspicuous at dorsal surface of tail. Lip region moderately angular, offset by a marked depression, 2.3-2.8 times as broad as high, ca one-third of body diam. at neck base, lips mostly amalgamated, labial papillae distinct, visibly protruding above lip region contour. Amphid fovea cup-shaped, opening at level of labial depression, aperture 8-10 µ m or three-fifths to twothirds of lip region diam. Odontostyle typical of genus, comparatively long and slender, 1.5-2.0 µ m diam., ca 11.5-14.0 times as long as wide, 1.5-1.8 times longer than lip region diam. and ca 1.9% of total body length. Odontophore 1.3-1.7 odontostyle lengths long, with well developed basal flanges. Guiding ring ‘double’, situated at 15-17 µ m from anterior end. Pharynx consisting of slender but muscular anterior section enlarging gradually, basal expansion 3.5-3.8 times as long as broad, ca twice as long as body diam. at its level and occupying 35- 38% of total neck length, gland nuclei located as follows: DN = 68-72, AS obscure, PS = 52-59. Nerve ring situated at 125-133 µ m from anterior end. Cardia rounded conoid, (10-17) × (10-13) µ m, almost as long as wide. Distinct dorsal, ovoid to spindle-shaped cellular mass, ca 40 µ m long, present in all specimens between cardia and proximal end of anterior ovary. Green material observed inside intestine. Genital system didelphic-amphidelphic, both branches equally and well developed, anterior 247- 285 µ m and posterior 230-270 µ m long, ovaries usually large, 95-182 µ m long, often reaching and surpassing sphincter level, oviduct 115-150 µ m or 1.9-2.5 body diam. long, joining ovary subterminally, consisting of a tubular part and a well developed pars dilatata. Oviduct and uterus separated by a distinct sphincter. Uterus 95- 145 µ m long, tripartite, i.e., consisting of a wide proximal region with distinct lumen, a more slender intermediate section with very narrow lumen, and a well developed, spheroid distal portion. One or two uterine eggs, (86-97)× (37-51) µ m, observed within one or both genital tracts, with thick shell. Vagina extending inwards two-fifths to one-half of body diam., pars proximalis (19-22) × (18- 20) µ m, with somewhat sigmoid walls and surrounded by weak musculature, pars refringens consisting of (in lateral view) two triangular sclerotisations, measuring (5-6)×(5- 7) µ m; pars distalis 4.0-5.0 µ m long. Vulva a transverse slit. Prerectum 2.5-3.5 anal body diam. long. Rectum 25- 36 µ m or almost as long as anal body diam. Tail rounded conoid, ventrally almost straight, dorsally convex, a few large and distinct saccate bodies present in ventral region. Two pairs of caudal pores, one subdorsal, one practically lateral (in one female three pores observed).

Male Unknown.

TYPE HABITAT AND LOCALITY

Soil in the rhizosphere of grasses, Shalmash village , Sardasht , western Azarbayjan, north-western Iran .

TYPE MATERIAL

Female holotype and five female paratypes deposited in the Nematode collection of the Faculty of Agriculture, University of Tarbiat Modarre, Tehran, Iran. Five female paratypes deposited with the Nematode Collection of Departamento de Biología Animal, Biología Vegetal y Ecología, University of Jaén, Spain and two paratype females deposited with USDA Nematode Collection, Beltsville, MD, USA.

DIAGNOSIS AND RELATIONSHIPS

The new species is characterised by its body length of 1.3-1.5 mm, lip region offset by marked depression and 13-15 µ m broad, odontostyle 22-27 µ m long or 1.5- 1.8 times the lip region diam., neck 290-310 µ m long, pharyngeal expansion 100-110 µ m long or 35-38% of total neck length, a dorsal cellular mass present between cardia and proximal end of anterior ovary, uterus tripartite and 95-145 µ m long, V = 44-48, female tail rounded conoid (19-23 µ m, c = 61-76, cļ = 0.7-0.8) and bearing saccate bodies, and male unknown.

Having a comparatively small size (L * 1.5 mm), narrow lip region (up to 15 µ m) and short odontostyle (<30 µ m), E. sardashtensis sp. n. is very similar to E. altherri Vinciguerra & De Francisci, 1973 and E. arcticus Nesterov, 1976 , two close, poorly described, species (see also remarks), only known to occur in their corresponding type locations (cf., Guerrero et al., 2008). It differs from E. altherri in its shorter odontophore (35-37 vs 42-45 µ m) and total stylet length (58-65 vs 67-72 µ m), longer neck (290-310 vs 236-276 µ m), more anterior vulva (V = 44- 48 vs 50-52), shorter female tail (c = 61-76 vs 55-58), and male absent vs present, and from E. arcticus in its longer odontostyle (ca 1.5-1.8 vs 1.2 times the lip region diam.), relatively shorter pharyngeal expansion (35-38 vs ca 43% of total neck length), more anterior vulva (V = 44-48 vs 49-51), shorter female tail (19-23 vs 23-31 µ m, c = 61- 76 vs c = 48-53) with vs without saccate bodies, and male absent vs present.

MOLECULAR STUDY

Ribosomal DNA near-full-length small subunit 18S gene of E. sardashtensis sp. n. was sequenced and deposited in GenBank under accession number HQ404367 . Sequencing on internal transcribed spacer and partial 5.8S gene was not successful. Blast search revealed this sequence is unique without identical match with any other species in GenBank. The 18S of this species had 99% identity with E. macrodorus voucher M53 from Iran ( FJ042953 ) with 3 bp differences over 1190 bp aligned sequences, Enchodelus sp. ( AY284793 ) with 5 bp differences over 1311 bp aligned sequences, Enchodelus sp. ( AY284792 ) with 9 bp differences over 1311 bp aligned sequences, Enchodelus sp. (EP207247) with 12 bp differences over 1311 bp aligned sequences, and 96% identity with E. veletensis voucher M34 from Iran ( EU477379 ) with 38 bp differences and 3 gaps over 1193 bp aligned sequences. Phylogenetic analysis revealed that E. sardashtensis sp. n. is closest to E. macrodorus M53 ( Fig. 4 ) and is in the round-tail clade ( Fig. 5 ). This 18S fragment is very conserved; E. sardashtensis sp. n. has identical sequence with E. babakicus , E. longispiculus , E. macrodorus and E. hopedorus .

REMARKS

Some (although minimal) doubts persist as to the true identity of this Iranian population due to the fact that the original descriptions of its most similar species, E. altherri and E. arcticus , lack many details necessary to carry out a detailed comparison. Nevertheless, the differences observed, especially those concerning the length of odontostyle/odontophore/total stylet, pharynx length and vulva position, are significant enough to support the proposal of a new taxon.

Figures

Fig. 2. Enchodelus sardashtensis sp. n. (female). A: Neck region; B, D: Lip region in surface view; C: Anterior region in median view; E: Entire body; F, G: Anterior genital branch; H: Posterior body region; I-K: Tail with saccate bodies.

Fig. 3. Enchodelus sardashtensis sp. n. (LM, female). A: Entire body; B, C: Anterior region in median view showing odontostyle (B) and odontophore (C); D: Lip region and odontostyle; E: Pharyngo-intestinal junction; F: Neck region; G: Pharyngeal expansion; H: Dorsal cellular mass (arrow) between cardia and proximal end of anterior ovary; I: Tail. (Scale bars: A = 200 µm; B-D, I = 10 µm; E, G, H = 20 µm; F = 50 µm.)

Fig. 4. Bayesian consensus tree inferred from 18S under GTR + I + G model (lnL = 5297.7065; AIC = 10 615.4131; freqA = 0.2752; freqC = 0.2114; freqG = 0.2621; freqT = 0.2512; R(a) = 1.8482; R(b) = 5.0147; R(c) = 2.8536; R(d) = 0.2499; R(e) = 11.081; R(f) = 1; Pinva = 0.2089; Shape = 0.7502). Posterior probability values exceeding 50% are given on appropriate clades.

Fig. 5. Bayesian consensus tree inferred from 18S small under TVMef + I model (lnL = 1172.5674; AIC = 2355.1348; freqA = 0.2416; freqC = 0.1799; freqG = 0.2957; freqT = 0.2828; R(a) = 1.6906; R(b) = 8.6571; R(c) = 4.9786; R(d) = 0.5884; R(e) = 8.6571; R(f) = 1; Pinva = 0.6319; Shape = equal). Posterior probability values exceeding 50% are given on appropriate clades.