Dorylaimopsis intermedia, Gagarin, Vladimir G., 2013

Gagarin, Vladimir G., 2013, Four new species of free-living marine nematodes of the family Comesomatidae (Nematoda: Araeolaimida) from coast of Vietnam, Zootaxa 3608 (7), pp. 547-560 : 555-557

Dorylaimopsis intermedia sp. n.

( Fig.4 , Table 4)

Type specimens. Holotype male, inventory slide no. 102/6 deposited in the collection of the helminthological museum of the Institute of Ecology and Evolution, Center of Parasitology, Russian Academy of Sciences, Moscow, Russia. All paratype slides deposited in the nematode collection of the Institute of Ecology and Biological Resources, Vietnamese Academy of Science and Technology, Hanoi, Vietnam.

The habitat and locality. South China Sea, littoral zone off the coast of Vietnam, Tea Co. Latitude: 21 25.712’ –21 27. 521’,. Longitude: 107 58.952’ – 108 02.124’. Depth 1.0– 2.5 m, sand, salinity 29.1–29.5‰.. Collected in March 2010.

Description. Male. Body slender, medium-sized, tapering toward both extremities. Cuticle marked by transverse rows of fine punctations. Lateral differentiation consisting of four longitudinal rows of larger dots beginning just posterior to amphidial fovea, extending down almost to base of pharynx and then taking the form of a series of coarse dots in two longitudinal files, terminating at the level of the cloaca. Lateral differentiation 8.5–9 µm wide at mid-body, 12–14% of corresponding body diameter. Punctation on tail in four longitudinal rows of dots. Somatic setae rare and sparse, 4–5 µm long. Head slightly isolated from the rest of the body. Inner labial sensillae in the shape of large papillae. Outer labial sensillae and cephalic sensillae in the shape of thin setae, with both circles of setae quite close together. Four cephalic setae 9–12 µm long (80–90% of labial region width). Outer labial setae slightly shorter. Amphidial fovea in the shape of spiral with tree turns and occupying about 70% of corresponding body diameter. The mouth opens into cup-shaped anterior portion of stoma, followed by 24–26 µm long heavily cuticularized tubular portion armed with three strong triangular teeth at anterior end. Pharynx widens towards its base, but without distinct bulb. Renette 24– 36 x 16–25 µm in size, situated at level of cardia. Excretory pore posterior to nerve ring. Two testes, opposite and outstretched. Spicules paired, equal and strongly curved, 149–162 long (along arc), 3.3–3.8 cloacal body diameter, proximal end slightly cephalated and with short median cuticularized strip. Gubernaculum with two caudally-dorsally directed apophyses 29–32 µm long. Precloacal supplements not observed. Tail slender, with rather broad, conical anterior portion and rather narrow cylindrical posterior portion, the latter 0.6–0.7 times as long as anterior conical portion. Tail with numerous short caudal setae. Tail tip slightly enlarged, with three terminal setae 12–14 µm long. Caudal gland and spinneret present.

Female. Similar to male in general characteristics. Structure of cuticle and anterior body end as in male. Cuticle marked with transverse rows of punctations. Lateral differentiation in pharyngeal region and at tail consisting of four longitudinal rows of larger dots and along rest of body with two longitudinal rows of dots. Inner labial sensillae in the shape of papillae and outer labial sensillae and cephalic sensillae in the shape of thin setae. Cephalic setae length approximately 80% of labial region width. Amphidial fovea in the shape of a spiral with 3.0 turns and occupying 55% of corresponding body end. Stoma in the shape of cuticularized tube 25 µm long, armed with three triangular teeth at anterior end. Pharynx widens towards its base. Rectum 0.9 times as long as anal body diameter. Reproductive system didelphic, amphidelphic; ovaries homodromous, comparatively short. Anterior ovary situated on the right side of intestine, posterior ovary on the left side of intestine. Vulva equatorial, in the shape of a transverse slit, lips not cuticularized and not protruding outside the body contour. Vagina straight and short. Both uteri spacious, filled with numerous spermatozoa. Tail slender, comparatively long, its anterior portion conical, and then gradually narrowing, thin with short terminal swelling. Tail tip with three subterminal setae. Caudal glands and spinneret present.

Differential diagnosis. Dorylaimopsis intermedia sp. n. is morphologically similar to D. mediterranea Grimaldi de Zio, 1968 and D. magellanense Chen &Vincx, 1998 . It differs from both species in the longer outer labial setae and absence of precloacal supplements in males. It differs from the former in the longer cephalic setae (10–12 µm long, 75–80% of labial region width vs 3.7–7.5 µm long, 33–50% of labial region width in D. mediterranea ) and shorter spicules (149–164 µm vs 182–200 µm in D. mediterranea ) (Grimaldi de Zio, 1968). D. intermedia n. sp. differs from D. magellanense in the longer cephalic setae (10–12 µm long, 75–80% of labial region width vs 7 µm long, 35–52% of labial region width in D. magellanense ), longer spicules (149–164 µm long vs 143–150 µm long in D. magellanense ) and shorter gubernaculum (29–33 µm long vs 46–59 µm long in D. magellanense ) (Chen, Vincx, 1998).

Character Holotype Paratypes

male 7males 1female L 1888 1863 + 95 (1746–2016) 2093 a 34 29 + 3 (26–34) 35 b 7.5 7.7 + 0.2 (73–80) 8.1 c 11.2 11.4 + 0.8 (10.0–12.3) 11.9 c’ 3.8 3.8 + 0.2 (3.4–4.1) 4.2 V % – – 50.2 Labial region width 13.0 13.5 + 0.5 (13.0–14.0) 15 Cephalic setae length 11.0 11.0 + 0.7 (9.0–10.0) 12 Stoma length 25 24 + 1 (24–26) 25 Amphidial fovea diameter 25.0 24+0.7 (24–25) 25 Oesophagus length 252 241+13 (225–257) 259 Distance from posterior end of pharynx to vulva – – 792 Distance from posterior end of pharynx to cloaca 1467 1458 + 86 (1350–1598) – Distance from vulva to anus – – 866 Body width 56 64 + 7 (56–77) 60 Anal (cloacal) body diameter 45 43 + 2 (41–46) 42 Tail length 169 164 + 7 (153–176) 176 Spicules length (along arc) 162 157 + 6 (146–164) – Dorsal apophysis of gubernaculum length 30 31 + 2 (29–33) –

Figures

FIGURE 4. Dorylaimopsis intermedia sp. n. A: Entire male; B: Entire female; C: Male head; D: Cardial region of male; E; Spicular apparatus; F: Male tail; G: Female tail. Scale bars: A, B— 100 µm; D – G— 50 µm; C— 15 µm.