Enchodeloides, Elshishka, Milka, Lazarova, Stela, Radoslavov, Georgi, Hristov, Peter & Peneva, Vlada K., 2017

Elshishka, Milka, Lazarova, Stela, Radoslavov, Georgi, Hristov, Peter & Peneva, Vlada K., 2017, Biogeography and phylogenetic position of Enchodeloidessignyensis (Loof, 1975), gen. n., comb. n. from Maritime Antarctic (Nematoda, Nordiidae), ZooKeys 697, pp. 37-58 : 42-45

Enchodeloides gen. n.

Diagnosis.

Nordiidae . Nematodes of medium size. Cuticle dorylaimoid, consisting of four layers, outer layer finely, inner layer coarsely transversally striated. Lip region angular; stoma entrance surrounded by a moderately developed cuticularised ring, appearing as small perioral refractive dots. Amphidial fovea cup-shaped, its aperture about half of lip region diameter, curved. Odontostyle short and slender, straight. Odontophore with small swellings. Guiding ring double. Anterior region of pharynx enlarging gradually into pharyngeal expansion. Posterior pair of pharyngeal nuclei smaller than dorsal nucleus, located posteriorly in pharyngeal expansion. Cardia rounded conoid. Female genital system amphidelphic. Uterus not differentiated. Vagina moderately sclerotised. Vulva a transverse slit. Males rare. Spicula stout ventrally curved. Lateral guiding pieces present. Sperm cells spindle-shaped. Supplements 2 to 4 in number preceded by an ad-cloacal pair of papillae, starting far behind the level of the spicules. Tail bluntly conoid, with numerous saccate bodies on tail. First juvenile stage with elongate conical tail with long central peg.

Relationships.

The new genus resembles members of the subfamily Pungentinae Siddiqi, 1969, especially the genera Enchodelus , Pungentella Andrássy, 2009, Pungentus and Stenodorylaimus Álvarez-Ortega & Peña-Santiago, 2011. It differs from Enchodelus by having lip region with six radial striae starting from inner and ending at outer labial papillae vs absent (seen under SEM), four vs three layered cuticle, two vs one thicker inner layer at tail region (under light microscopy), cheilostom thin walled vs thick walled, a moderately developed cuticularised ring around the oral ap erture vs absent; less developed vs well developed basal swellings; a pharynx enlargement gradually expanding vs abruptly expanding into basal expansion (Fig. 4G, H), the posterior pair of pharyngeal nuclei generally smaller than dorsal nucleus vs as large as dorsal nucleus ( Andrássy 2009), except for E. macrodorus Thorne, 1939 ( Guerrero and Peña-Santiago 2007) and located more posteriorly, more than 89% vs 83-88% of the pharyngeal expansion ( Loof and Coomans 1970); less complex uterus vs tripartite (bipartite in E. distinctus Ahmad & Jairajpuri, 1980 and E. ponorensis Popovici, 1995); posteriormost ventromedian supplement located at a considerable distance from the adcloacal pair and outside of the spicule range vs posteriormost one or two ventromedian supplements rather close to the adcloacal pair and inside the spicule range, 2-4 vs 7-16 in number, and finally, all representatives of the genus Enchodelus have been reported only from the northern hemisphere. Enchodeloides gen. n. differs from Pungentella by having transversally striated cuticle vs smooth; a longer odontostyle (much longer vs equal to or slightly longer than lip region diam.) with a smaller aperture (up to one-sixth vs one-fourth to one-third its length); a moderately developed cuticularised ring vs four small platelets around the oral aperture and the guiding ring double vs simple. From Pungentus it differs in having a moderately developed cuticularised ring vs four distinct circumoral platelets around the oral aperture; a straight vs arcuate odontostyle; shorter odontostyle (1.2-1.6 times vs 2-3 times lip region diameter ( Andrássy 2009 a); the first pair of ventrosublateral pharyngeal gland nuclei indistinct, difficult to observe vs well developed; a long distance DO-DN (5-6% vs 2-4% ( Loof and Coomans 1970)); ventromedian supplements located at a considerable distance from the adcloacal pair and outside of the spicule range vs posteriormost 1-4 supplements lying within the spicule range, and with vs without hiatus. From the genus Stenodorylaimus it differs by having a shorter body (L=1.2-1.9 vs 3.7-5.1 mm), and a slender vs more robust odontostyle (1.2-1.7 vs 0.51-0.87% of body length); a longer pharynx (b-ratio up to 6 vs more than 7); saccate bodies present vs absent; the first pair of ventrosublateral pharyngeal gland nuclei indistinct, difficult to observe vs well developed; ventromedian supplements spaced vs irregularly spaced, 2-4 vs 14-19 in number, and with vs without hiatus.

Consequently, the new combination Enchodeloides signyensis (Loof, 1975) is proposed to accommodate the only nordiid species occurring in Maritime Antarctic.