Dorylaimopsis variabilis

Hong, Jung-Ho, Kim, Hyeonggeun, Kim, Kichoon, Lee, Seunghan & Lee, Kanghyun Lee and Wonchoel, 2023, Two unrecorded species of the family Comesomatidae Filipjev, 1918 (Nematoda: Araeolaimida) from Korea, Journal of Species Research 12 (2), pp. 122-149 : 125-129

Dorylaimopsis variabilis

Muthumbi, Soetaert and Vincx, 1997

( Figs. 1-4 , Table 1)

Locality. The coast of Ulsan: sub-tidal southern part of East Sea, Korea (35°37′35″N, 128°28′9″E), at a depth of 90 m, in clay sediment .

Material. Four males (NIBRIV0000900857, NIBRIV 0000900859, NIBRIV0000900860, NIBRIV0000900862) and three females (NIBRIV0000900863-NIBRIV00 00900865) collected by Sangjin Kim along the coast of Ulsan on 5th September 2012, from Research Vessel Hansudan 1 .

Measurements. See Table 1 for detailed measurements and morphometric ratios.

Description. Male ( Figs. 2 , 4 , Table 1). Body cylindrical, gradually tapering toward both extremities, with blunt anterior end. Cuticle thin and punctuated. Fine dots started about anterior edge of amphids. Laterally modified punctuations begun at the posterior level of amphids, larger and more widely arranged on pharyngeal and tail regions. Laterally modified punctuation changed three times; at posterior amphids; near base of pharynx; around anus. Punctuations irregularly arranged on post amphidial regions; three rows on pharyngeal region; two rows in mid body; three rows on tail, finishing about 90 μm before tail tip. Lateral differentiations about 6-7 μm at base of pharynx, 6-7 μm in mid-body, 8-9 μm in anus region. Tail conico-cylindrical.

Anterior sensilla in three separate crowns, six inner labial sensilla small, with papillae form. Six outer labial sensilla short setiform. Four cephalic setae (5.8-7.5 μm) nearly equal length, located 0.5 head diameter from anterior end. Somatic setae (about 3-4 μm), in four dorso- and ventrolateral longitudinal rows scattered on body, much shorter than cephalic setae. Amphidial fovea (8.8- 9.0 μm) large, 5.8-6.6 μm behind anterior end, situated behind cephalic setae, circular spiral form. Fovea spiral coiled ventrally, about 2.5 turns.

Buccal cavity composed with small cup-shaped anterior portion (about 2 μm deep) and sclerotized cylindrical posterior portion (19-21 μm deep) with three teeth. Pharynx long (208-226 μm) and slender, cylindrical except distinct posterior bulb (23-26 μm, cbd 42-46 μm). Nerve ring located at 101-118 μm (46.8-52.2%) of pharyngeal length from anterior end. Ventral gland pore just posterior nerve ring, situated at 116-134 μm of pharyngeal length from anterior end. Cardia round, small (8-9 μm), surrounded with intestinal tissue. Ventral gland cell body placed posterior of cardia.

Reproductive system diorchic, testes outstretched, anterior testis (situated left mid-gut) located 1049-1368 μm and posterior testis (situated right mid-gut) located 394-492 μm from the cloaca. Spicules paired, equal and long, arcuate and have a capitulum, 86-91 μm long as arc (2.3-2.4 abd). Gubernaculum very strongly sclerotized pieces, bearing caudal apophysis (13-22 μm) with swollen distal tip, surrounding spicules. Thirteen to fourteen minute mid-ventral supplementary papillae observed in precloacal region, several copulatory muscles located in pre-cloacal supplement region. First precloacal supplement situated about 14-16 μm from anus and most anterior precloacal supplement located 218-279 μm from anus. Tail consisted proximal conical and distal cylindrical part (30-40 μm). Tail 3.7-4.3 abd long with

A

C

A B D C E

three long terminal setae (about 7 μm long), three caudal glands, and prominent spinnerret. Other tail setae (about 3-5 μm) arranged in approximately eight dorso- and ventrolateral longitudinal rows.

Females ( Figs. 3, 4 , Table 1). Similar to male. Vulva at 47.3-56.1% of body of length. Didelphic, outstretched ovaries, anterior ovary (situated left mid-gut) 490-633 μm, posterior (situated right mid-gut) 543-604 μm long. Supplements absent.

Diagnosis. Dorylaimopsis . Body length 1745-1982 μm; a 31.7-38.9; b 8.1-9.5; c 11.2-14.2; c′ 3.7-4.6; s 2.3- 2.4. Outer labial sensilla short setiform, cephalic setae 6.0-7.5 μm. Laterally modified punctuations three rows at pharynx (6-7 μm), two rows at midbody (6-7 μm), three rows at anus (8-9 μm). Spicules curved, with a capitulum, 86-91 μm long in arc. Gubernacular apophysis caudally, 13-22 μm long. Thirteen to fourteen minute precloacal supplements present. Tail conico-cylindrical, 140-158 μm long, cylindrical portion 20-32%.

Remarks. Dorylaimopsis variablilis is morphologically similar to D. angelae , D. brevispicuia , D. gerardi , D. janetae , D. jinyuei , D. nini , D. papilla , D. poriferum , D. rabalaisi , D. timmi and D. turneri in the shape of tail, spicule, gurbernaculums. However, there are differences in the pattern of lateral differentiation, body length, body ratio, cephalic setae length, amphidial fovea turns. The morphometry of D. angelae , D. brevispicuia , D. gerardi , D. janetae , D. jinyuei , D. nini , D. papilla , D. poriferum , D. rabalaisi , D. timmi and D. turneri are summarized in Table 2. Dorylaimopsis intermedia , D. magellanense , D. mediterranea , D. nodderi , D. perfecta , D. punctata and D. tumida can be distinguished from D. variabilis by spicule shape and (jointed or with a ventral apophysis in spicules vs simply curved spicule in D. variabilis ). Dorylaimopsis coomansi is dissimilar to D. variabilis by having gubernacular apophysis without a blunt tip. Dorylaimopsis longispicula can be separated from D. variabilis by having much long spicules (179-196 μm vs 86-127 μm). Dorylaimopsis boucheri , D. communis , D. halongensis , D. lutosa and D. peculiaris can be differed from D. variabilis by tail shape and length. Dorylaimopsis poriferum can be divided from D. variabilis by cuticle with two rows of coarse dots in males and three in female. The present population of Dorylaimopsis variabilis resembles that of Muthumbi, Soetaert and Vincx, 1997 from the Kenyan coast in the Indian Ocean in general characters. They slightly differ from by amphidial fovea turns (2.5 turns vs 2.75-3.00 turns), body length (1745-1943 μm vs 1119-2533 μm), body width (49-52 μm vs 35-87 μm) and the relative length of tail (c′: 3.7-4.3 vs 2.9-3.9). We consider such differences as intraspecific variation.

Figures

Fig. 1. Dorylaimopsis variabilis Muthumbi, Soetaert and Vincx, 1997 from East Sea, Korea, male 1: A. pharynx; B. head, showing amphideal fovea and cuticular ornamentation at head region; C. tail. Scale bars: 20μm (A-C).

Fig. 2. Dorylaimopsis variabilis Muthumbi, Soetaert and Vincx, 1997 from East Sea, Korea, male 1: A. copulatory apparatus; B. habitus; C. midbody. Scale bars: 20 μm(A, C) and 100 μm (B).

Fig. 4. Dorylaimopsis variabilis Muthumbi, Soetaert and Vincx, 1997 from East Sea, Korea. A. male pharynx, showing cuticular ornamentation at the base of pharynx, male 1; B. male midbody, showing cuticular ornamentation at midbody, male 1; C. male cloacal region, showing cuticular ornamentation at the cloaca, male 1; D. female vulva, female 1. Scale bars: 20μm (A-C) and 50μm (D).