Parasphaerolaimus jintiani, Cai, 2017

Cai, Lizhe, 2017, Two new ovoviviparous species of the family Selachinematidae and Sphaerolaimidae (Nematoda, Chromadorida & Monhysterida) from the northern South China Sea, Zootaxa 4317 (1), pp. 95-110 : 101-104

Parasphaerolaimus jintiani n. sp.

( Figs. 4–5 , Table 2)

Type material. Male holotype, slide 20110907. The specimen was collected from mangrove wetland nature reserve of the Zhangjiang Estuary in the northern South China Sea, coordinates: 23.930° N, 117.417° E, surface sediment layer (0–10 cm), muddy sediment. Paratypes, three females and one juvenile, slide 20110908, slide 20110909 and slide 20110998. Specimens were also collected from the same location, coordinates: 23.923° – 23.932° N, 117.413°–24.415° E, surface sediment layer (0–10 cm), muddy sediment.

Etymology. The species is named after the elder son of the first author Sujing Fu.

Description. Male body stout. Cuticle faintly striated with lateral longitudinal unstriated band extending from about the middle of the pharynx to the anterior two-thirds of the tail. Internal labial papillae, six external labial setae (3 µm) and four cephalic setae (5 µm) in one circle, situated posterior to the level of the distal end of the first cuticularised articulated plates. Somatic setae about 6 µm long, numerous in the pharyngeal region and sparse elsewhere. Amphids circular with a posterior break. Buccal cavity in two parts. The anterior portion large, 93 µm deep and 73 µm wide, with six strongly cuticularised articulated plates (196 µm long in total), posterior portion, 40 µm deep and 22 µm wide, with strongly cuticularised rim. Posterior portion of buccal cavity surrounded by pharyngeal tissue. Pharynx cylindrical. Cardia triangular. Nerve ring not observed. Secretory-excretory system not observed.

Anterior testis single, outstretched. Spicules, slightly arcuate, with swollen proximal ends and pointed distal ends. Gubernaculum without apophyses, parallel to the spicules. Tail conico-cylindrical, with caudal glands. Long and sparse caudal setae present sub-ventrally, three very long terminal setae, 32 µm long.

Females s imilar to males but with a shorter body length and weaker maximum body diameter, smaller mean value of a and smaller amphid diameters. Reproductive system monodelphic, with anterior ovary situated at the right of intestine. Female gonad consisting of about nine oocytes with granular cytoplasm and clear nucleus. Posterior to the oocytes region is a sequence of developing eggs and shelled embryos. One uterus can contain about nine fertilized eggs and embryos, and sometimes a few hatched juveniles. Vagina situated far posteriorly and about 91 µm from the anal opening. No vulvar glands observed.

Diagnosis. Parasphaerolaimus jintiani n. sp. is characterized by a relatively long body (1286–2490 µm), buccal cavity consisting of six strongly cuticularised articulating plates anteriorly and strongly cuticularised rim posteriorly, cuticle with lateral longitudinal unstriated bands, gubernaculum without apophyses and parallel with spicules. Tail conico-cylindrical with three long terminal setae.

Differential diagnosis. Parasphaerolaimus jintiani n. sp. can be differentiated from the seven species P. paradoxus , P. antiae , P. brevisetosus , P. crassus , P. dispar , P. lodosus and P. polaris by the presence of lateral longitudinal unstriated bands or alae on cuticle. Furthermore, large values of V-index are known for some other species in the Sphaerolaimidae family, such as V = 69% in P. antiae , V = 55.5%–67.1% in P. pilosus , V = 62% & 71% in Sphaerolaimus kleini Jensen, 1992 , V = 76.6%–79.6% in S. pacificus Allgén, 1947 and V = 83% in P. lodosus , but not as great as in Parasphaerolaimus jintiani n. sp. which has very high V-index (85%). Position of the vulva very close to the anus in the new species is unique for the family. The new species has a buccal cavity similar to P. paradoxus but differs from this species by shorter cervical setae (6 µm vs 24–34 µm), swollen proximal ends of spicules and gubernaculum without apophyses. The new species differs from P. antiae which has irregularly shaped plates in the buccal cavity. In addition, Parasphaerolaimus jintiani n. sp. can be distinguished from other species of Parasphaerolaimus by much longer spicules (109 µm) and gubernaculum (48 µm).

Figures

FIGURE 4. Parasphaerolaimus jintiani n. sp. A: Entire male, showing lateral longitudinal unstriated band on CutiCle. B: Entire female. C: Anterior body region of female. D: Male head. E: Female head. F: Female posterior body region. G: Male posterior body region.

FIGURE 5. Parasphaerolaimus jintiani n. sp. Light miCrographs. A: Anterior body region of viviparous female. B: Male head. C: Amphid of male. D: Lateral longitudinal unstriated band (arrow) on CutiCle. E: SpiCular apparatus. F: Female posterior end, showing vulva region (arrow).