Enchodelus longispiculus, Guerrero & Liébanas & Santiago, 2008

Guerrero, Pablo, Liébanas, Gracia & Santiago, Reyes Peña-, 2008, Nematodes of the order Dorylaimida from Andalucía Oriental, Spain. The genus Enchodelus Thorne, 1939. 3. Description of two new and one known species with rounded tail and medium-sized odontostyle, Nematology 10 (5), pp. 711-733 : 723-725

Enchodelus longispiculus * sp. n.

( Figs 4C, E, F ; 7 , 8 )

MATERIAL EXAMINED

Forty-eight females and 29 males collected in Sierra Nevada, province of Granada.

MEASUREMENTS

See Table 2.

DESCRIPTION

Female

Moderately slender to stout, medium-sized nematodes, 1.32-1.87 mm long. Habitus after fixation slightly curved ventrad, adopting an open C- or J-shape. Body cylindrical, tapering towards both ends but more so anteriorly. Cuticle 3.5-5.5 µ m in anterior region, 3.0-4.5 µ m at mid-body and 5.5-9.5 µ m on tail; its outer layer with very fine transverse striations and much thinner than inner, especially at tail level. Lateral chord relatively narrow, 7.0-12.0 µ m wide or occupying 9-17% of mid-body diam., granular, lacking any particular differentiation. Lateral pores obscure. Lip region moderately angular, offset by shallow depression, 2.4-3.7 times as broad as high and ca oneto two-fifths of body diam. at neck base. Lips amalgamated; labial and cephalic papillae distinct, moderately protruding above cephalic contour. Under SEM, oral aperture rhomboid, located on moderate elevation of perioral area; inner and outer labial papillae surrounded by ring-like differentiation of body surface offset by circular striation; cephalic papillae on less marked areas. Amphid fovea cup-shaped, opening at level of cephalic depression, occupying one-half to three-fifths of corresponding body diam. Under SEM, pore visible slightly posterior to amphidial fovea surface. Cheilostom cylindrical but with marked constriction at its middle. Odontostyle long and slender, 12-16 times as long as wide or 1.6-1.9 times longer than lip region diam.; aperture small, occupying 5-13% of total length. Odontophore 1.2-1.5 times longer than odontostyle, with distinct basal flanges over posterior half of its total length, consisting of six sclerotised pieces with basal knobs. Guiding ring double, located at 16-19 µ m or 0.9-1.2 times lip region diam. from anterior end. Pharynx consisting of slender muscular anterior portion expanding gradually into basal expansion at 61-70% of total neck length, reaching full diam. at 66-74%; pharyngeal expansion occupying 28-37% of total neck length and ca two- to three-fifths of corresponding body diam. Pharyngeal gland nuclei located as follows (n = 22): DN = 69-75; S 1 N 1 = 26-31 (n = 3); S 1 N 2 = 33- 37 (n = 3); S 2 N 1 = 51-60; S 2 N 2 = 53-60. Weak membrane-like structure surrounding base of pharyngeal expansion. Cardia rounded conoid, wider than long, 11- 19 × 10-17 µ m. Intestine containing olive green or brownish material. Genital system didelphic-amphidelphic, both branches equally and well developed. Ovaries 78-293 µ m long, usually surpassing sphincter level; oocytes first in two or more rows, then in one. Oviduct 95-231 µ m or 1.3-3.1 times corresponding body diam. long, consisting of slender portion with prismatic cells and well developed pars dilatata with distinct lumen. Distinct sphincter between oviduct and uterus. Uterus long, 160-283 µ m or 2.2-3.9 times corresponding body diam., sometimes twisted; tripartite, i.e., consisting of: i) a wider proximal region with distinct lumen; ii) followed by a narrower and shorter intermediate portion with narrow lumen and surrounded by a cluster of hyaline cells; and iii) ending with a well developed spheroid pars dilatata distalis. Fourteen females bearing one to three eggs measuring 75-87 × 32- 46 µ m. Thirty out of 40 females containing sperm inside genital system. Vagina extending inwards for 41-64% of body diam.; pars proximalis longer than broad, 20- 34 × 11-26 µ m, with sigmoid to straight walls, surrounded by weak circular musculature; pars refringens with (in lateral view) two arcuate drop-shaped sclerotisations with combined width of 16-24 µ m and divided into proximal and distal area by change in refringence; pars distalis 1.5- 6.0 µ m long. Vulva a transverse oval slit. Prerectum 2-5 and rectum 0.8-1.6 anal body diam. long. Tail rounded conoid; terminal cuticle 6.5-14.0 µ m thick or 28-76% of total tail length, its inner layer marked by radial striation and divided into two by a discontinuity along its middle; aspect of cuticle rather variable, ranging from presence of saccate bodies or small irregularities to no differentiation at all; some individuals showing very faint discontinuity dividing inner layer of cuticle along its middle. Two pairs subterminal caudal pores, one lateral, another subdorsal.

Male

General morphology similar to female, although posterior region more curved, adopting a J- or G-shape. Lateral chord narrower than in female, 3.0-8.0 µ m wide or occupying 5-9% of body diam. Pharyngeal gland nuclei located as follows (n = 20): DN = 70-75; S 1 N 1 = 21- 27 (n = 2); S 1 N 2 = 32-37 (n = 2); S 2 N 1 = 48- 61; S 2 N 2 = 52-63. Genital system diorchic, testes opposed. Sperm spindle shaped, 8.5-11.0 µ m long. In addition to acloacal pair, a series of 8-14 more or less regularly spaced ventromedian supplements present, posteriormost two being within spicule range; in few cases ventromedian supplements irregularly spaced forming two or three groups; in three specimens, only one supplement located within spicule range. Posterior supplement located at 15- 35 µ m from adcloacal pair, latter being 10-14 µ m from cloaca aperture. Spicules dorylaimoid, relatively long due to extension of dorsal surface of head (manubrium), 4.3- 5.4 times as long as wide and 1.9-2.3 times longer than anal body diam. Lateral guiding pieces 13.5-17.5 × 3.5- 4.5 µ m, with bifurcate tip. Prerectum considerably longer than in female, 4-8 times anal body diam. Tail rounded conoid, practically straight ventrally, terminal cuticle 5.5- 11.5 µ m thick or 20-47% of total tail length; aspect of cuticle variable as in female, although saccate bodies, if present, generally less pronounced.

TYPE HABITAT AND LOCALITY

Wet meadow at 2925 ma.s.l. in Sierra Nevada (province of Granada, Spain). Enchodelus macrodorus also occurred in this site.

OTHER HABITATS AND LOCALITIES

The species has been collected from three other samples, all in Sierra Nevada, province of Granada, viz. a gorse scrubland at 2700 m a.s.l. and two wet meadows at 2590 and 2600 ma.s.l.

TYPE MATERIAL

Twenty females (holotype and paratypes) and five paratype males on slides 311-317, deposited in the Departamento de Biología Animal, Biología Vegetal y Ecología, Universidad de Jaén, Spain. Four paratype females and three paratype males deposited in the Nematode Collection of the United States Department of Agriculture, Beltsville , MD, USA.

DIAGNOSIS AND RELATIONSHIPS

Enchodelus longispiculus sp. n. is characterised by its 1.32-1.87 mm long body, slightly angular lip region offset by a shallow depression and 15-18 µ m broad, odontostyle 27-31 µ m long or 1.6-1.9 times lip region diam., odontophore with distinct basal flanges and 1.2- 1.5 times longer than odontostyle, neck 251-315 µ m long, pharyngeal expansion 77-114 µ m long or 28-37% of total neck length, female genital system amphidelphic, uterus long and tripartite, pars refringens vaginae with two arcuate drop-shaped sclerotisations, vulva a transverse slit and pre-equatorial (V = 41-48), tail rounded conoid (17- 29 µ mlong, c = 49-90, c ļ = 0.6- 0.8 infemalesand 20-29 µ m long, c = 54-71, c ļ = 0.6- 0.8 in males), spicules 63-72 µ m long and presence of 8-14 regularly spaced ventromedian supplements, the two posteriormost being within the range of the spicules.

Its short rounded conoid tail and medium sized odontostyle (ca 30 µ m) make this species similar to E. altherri, E. ameliae sp. n., E. analatus, E. arcticus, E. georgiensis , E. hopedoroides, E. hopedorus and E. ponorensis. Nevertheless, it differs from these species by the following features: from E. altherri by its slightly longer body (1.32- 1.87 vs 1.18-1.38 mm) and longer odontostyle (27-31 vs 25-27 µ m), vulva located more anterior (V = 41-48 vs 50-52) and longer spicules (63-72 vs 50-52 µ m); from E. ameliae sp. n., certainly a very similar species, by its more robust body (a = 17-25 and mid-body diam. 64-80 µ m vs a = 26-29 and mid-body diam. 52-54 µ m), lip region offset by a slight depression vs constriction, vulva located anterior (V = 41-48 vs 47-50) and longer spicules (63-72 vs 49-60); from E. analatus by its shorter odontostyle, odontophore and total stylet (27-31, 36-44 and 64-74, respectively, vs 34, 47 and 81 µ m, as estimated from original drawing), vulva pre-equatorial (V = 41- 48 vs 51) and frequent presence of males vs not known; from E. arcticus, by its longer odontostyle, odontophore and total stylet (27-31, 36-44 and 64-74, respectively, vs 24-29, 29-33 and 56-64 µ m, as maximum range estimates from data on stylet length and original drawing), vulva pre-equatorial (V = 41-48 vs 49-51), longer spicules (63- 72 vs 58 µ m), and presence of 8-14 ventromedian supplements vs absence [sic] of any supplements apart from the adanal pair; from E. georgiensis by its longer body (1.32- 1.87 vs 0.88-1.10 mm), broader lip region (15-18 vs ca 12 µ m) and much longer spicules (63-72 vs 36-44 µ m); from E. hopedoroides by its slightly narrower lip region (16-18 vs 18-20 µ m), shorter odontostyle and total stylet (27-31 and 64-74, respectively vs 31-34 and 70-77 µ m), guiding ring located further anterior at 16-19 vs 19-23 µ m from anterior end, shorter neck (251-315 vs 317-442 µ m), shape of pars refringens vaginae (drop-shaped vs semicircular), slightly shorter prerectum (65-162 vs 140-369 µ m) and frequent presence of males vs not known; from E. hopedorus by its more anterior vulva (V = 41-48 vs 48-55), slightly broader lip region (16-18 vs 15-16 µ m), relatively shorter odontostyle (1.6-1.9 vs 1.9-2.2 times lip region diam.), guiding ring located further anterior at 16- 19 vs 18-21 µ m from anterior end, slightly shorter neck (251-315 vs 305-374 µ m), shorter tail (17-29 vs 27-39 µ m) and males frequent vs not known; and, finally, from E. ponorensis by its stouter body (a = 17-25 vs 30-39 and mid-body diam. 64-80 vs 50-61 µ m), lip region offset by a depression vs constriction, odontostyle, odontophore and total stylet slightly longer (27-31, 36-44 and 64-74, respectively vs 23-25, 33-38 and 55-63 µ m), shorter pharyngeal expansion (77-114 vs 150-245 µ m), uterus tripartite vs a simple tube, as illustrated in original description – a rather striking condition and to be interpreted cautiously, shorter tail (17-29 µ m long and c ļ = 0.6-0.8 vs 35-45 µ m long and c ļ = 0.9-1.3) and frequent presence of males vs absence.

Figures

Fig. 4. SEM micrographs. A: Enchodelus hopedoroides Altherr, 1963, anterior end, dorsoventral, en face and semi en face views; B: E. ameliae sp. n., anterior end, lateral, en face and semi en face views; C: E. longispiculus sp. n., anterior end, lateral and two semi en face views; D: E. hopedoroides vulval region; E: E. longispiculus vulval region; F: E. longispiculus male posterior end. (Scale bars: A-C = 10 µm; D, E = 20 µm; F = 25 µm.)

Fig. 7. Enchodelus longispiculus sp. n. A: Male entire body; B: Female entire body; C: Female anterior region; D: Reconstruction of superficial appearance of anterior region, lateral view; E: Female neck; F: Female anterior genital branch; G: Vulval region; H: Male posterior end; I: Female tail; J: Male tail. (Scale bars: A, B = 500 µm; C, D, G, I, J = 50 µm; E, F, H = 100 µm.)

Fig. 8. Enchodelus longispiculus sp. n. A: Variability of anterior region (females); B: Variability of anterior region (males); C: Neck showing location of dorsal gland nucleus (large arrow) and one of subventral gland nuclei (small arrow); D: Variability of vulval region; E: Sperm in male testis; F: Variability of anterior genital branch, showing location of sphincter between uterus and oviduct (arrows); G: Egg; H: Male posterior end; I: Variability of female tail; J: Variability of male tail. (Scale bars: A, B, D, E, I, J = 20 µm; C, F, H = 100 µm; G = 50 µm.)