Parasaveljevia uncinoa, Pastor, Catalina, Russo, Virginia Lo & Villares, Gabriela, 2015

Pastor, Catalina, Russo, Virginia Lo & Villares, Gabriela, 2015, Two new species of Parasaveljevia Wieser, 1953 (Thoracostomopsidae, Nematoda) from Argentinean coasts (Chubut, Argentina), Zootaxa 3999 (4), pp. 498-510 : 503

Parasaveljevia uncinoa n. sp.

( Fig. 2 (A‒I), Fig. 3 (A‒H); Fig. 6 ; Fig. 7 (C); Table 1)

Material examined. Holotype Male, CNP-NEM N° 1115, collected in winter, 13/06/2006 on “Playa Pozo” beach (42º 49’ S and 64º 53’ W), during low tide. This coastal area is characterized by rock outcrops forms easily eroded material as tuffs and siltstones. The specimens were collected from small tuff holes, covered by sediment and bordered with abundant Polysiphonia brodiei (Dillwyn) Sprengel, 1827 . Characteristics of surface sediment layer: mean particle size (Mean particle size, Q2= 0.22; Fine fraction, FF %=1.11; SO index = 0.65; SK index = 1.50). This species was found together with several specimens of Patagonema iubatum Pastor et al., 2014. Collector: Catalina Pastor.

Paratypes Six males and three females, same data as holotype mounted on slide numbers CNP—NEM N° 1116‒1117; 1119‒1121; 1124‒1127.

Measurements: see Table 1.

Description. Holotype: Male. One dorsal and two ventro-sublateral lips, rounded in lateral view, with at least one incision on each lip. Two inner labial setae (9 µm long) inserted near apex of each lip, six in total. Two cirri rectangular in shape, 10 Μm long, inserted on the outer surface of ventro sublateral lips at the level of insertion of inner labial setae. Outer labial and cephalic setae situated at the anterior end of cephalic capsule. Six outer labial setae, 48 Μm long, and four cephalic setae all of the same length (25 Μm).

Amphidial fovea indistinct. Front end of the head capsule having a visible junction with the oesophagus. Outer labial and cephalic setae (emerge) from small fenestrae, in anterior margin of cephalic capsule. Cervical setae present in two circles of 6 +2 setae (20 + 6 Μm long). The anterior part of the buccal cavity bowl shaped, covered by three corpulent and curved mandibular plates. Two mandibles large, similar in size (ventro-sublateral), with three lines of nine denticles, one small (dorsal), with two lines of six denticles. In both lateral sides of mandibles a hook is present, directed towards the centre of the mouth. Ventro-sublateral teeth present at level of the mandibular ring and articulated with it ( Fig. 2 E and C; Fig. 6 ). The pharynx has refringent cuticularization on last 100 µm anterior to the small cardia.

Reproductive system diorchic, testes opposed. Two spicules each 40 Μm long, arcuate, with velum, proximal end with well-developed cephalisation. Gubernaculum tubular, 3 Μm width with dorso-caudal apophysis (22 Μm long). One tubular-globular supplement (10 Μm long) situated 83 Μm in front of spicules. Three precloacal ( Fig. 3 B, G1) and two postcloacal ( Fig. 3 B, G2) papillae present. Tail 170 Μm long (AD = 3.4), conical to cylindrical toward the distal end with swollen tip. The tip of the tail lacking setae.

Female. Similar to male in general body shape. Lateral mandibles slightly smaller than in males, with only two rows of denticles. Ventro-sublateral and dorsal teeth smaller than in males ( Fig. 2 C). Reproductive system didelphic amphidelphic, ovaries reflexed. Vagina short, not thickened. Tail 155 Μm long (AD =3.68) without setae. Diagnosis and relationships. Parasaveljevia uncinoa n. sp. is characterized by having a long rectangular cirri, positioned at the level of the inner labial setae; rectangular mandibles with prominent lateral hooks, bearing denticles in three (or two) lines of nine (or six) each and six cephalic setae of the same length, inserted at the anterior end of an small head capsule.

The De Man’s ratios of P. uncinoa n. sp. and P. cirrifera, Wieser, 1953 , are similar, but the two species differ in the length of the cephalic capsule and shape of the mandibles. Parasaveljevia uncinoa has a greater number of denticles of different sizes on the mandibles, a smaller general body size, and shorter spicules, gubernaculum and tail.

Etymology. The specific name refers to the hooks found on lateral ends of mandibles. From the Latin word “uncino”.

Figures

FIGURE 6. Figure showing main characters that differ between genera Oxyonchus and Parasaveljevia. A. In apical view of Oxyonchus and Parassaveljevia; B. In cephalic capsule (lateral view); C. In cephalic capsule (ventral view).

FIGURE 7. Pictorial key of known Parasaveljevia species (with males). A. P. cirrifera, from Wieser, 1953; B. P. limitense n. sp.; C. P. uncinoa n. sp. Scale bar: 1 = 20 µm.

FIGURE 2. P. uncinoa n. sp. Line drawings. A. Head in apical view of male paratype; B. Cirri and cephalic setae on anterior end of female paratype; C. Head and buccal cavity of female paratype; D. Cirri and cephalic setae on anterior end of male holotype; E. Head and buccal cavity of male holotype; F. Posterior end of male holotype; G. Posterior end of female paratype; H. Vulva and gonadal apparatus of female paratype; I. Copulatory apparatus, spicule, gubernaculum of male holotype. Scale bar: 1 = 20 µm; 2 = 100 µm.

FIGURE 3. P. uncinoa n. sp. Micrographs of slide mounted specimens. A. Apical view male paratype; B. Cloacal aperture in subventral view of male paratype; C. Apical view male paratype. D. Head and buccal cavity of male holotype; E. Head and buccal cavity of male paratype, sensillae; F. Copulatory apparatus, spicule, gubernaculum of male paratype; G. Cuticularization of oesofagus in male holotype; H. Head and buccal cavity of male paratype, ventro sublateral tooth. Abbrev: VSlat MB = ventro sublateral mandible; VSlat tooth = ventro sublateral tooth; D tooth = dorsal tooth; Mb hook = mandible hook, G 1 = precloacal glands; G 2 = postcloacal glands. Scale bar: 1 = 20 µm.