Laimella filipjevi Jensen, 1979

Hong, Jung-Ho, Tchesunov, Alexei V. & Lee, Wonchoel, 2016, Revision of Cervonema Wieser, 1954 and Laimella Cobb, 1920 (Nematoda: Comesomatidae) with descriptions of two species from East Sea, Korea, Zootaxa 4098 (2), pp. 333-357 : 351-356

Laimella filipjevi Jensen, 1979

Figs 6–8 , Table 4

Locality. Station ES27: sub-tidal Southern part of East Sea (35˚15΄42˝ N, 129˚25΄11˝ E), at a depth of 100 m, in clay sediment.

Material. All the specimens are deposited in the National Institute of Biological Resources ( Republic of Korea). Seven males NIBRIV0000329872–NIBRIV0000329879 collected by Kwangsoo Kim at station SE 27 in September 2012, from Research Vessel Hansudan 1; and five females NIBRIV0000329880–NIBRIV0000329884 collected by Kwangsoo Kim at station SE 27 in September 2012, from Research Vessel Hansudan 1.

Measurements. See Table 4 for detailed measurements and morphometric ratios.

Description. Males ( Figs 6 , 8 , Table 4 ). Body cylindrical, tapering towards both extremities, with elongate tail. Cuticle thin, with faint, relatively fine cross striations throughout body. Cephalic cuticle thickened apically. Punctation in cuticle not visible. Head region distinctly narrow. Tail conico-cylindrical.

Anterior sensilla in three separate crowns. Six inner labial sensilla papilloid. Six outer labial setae located about 0.2 head diameter from anterior end. Four cephalic setae much longer than outer labial setae (200–250% of outer labial setae length) and of nearly equal length to each other. Outer labial and cephalic setae very close together, nearly at the same level. Somatic setae (about 4.0 µm) scattered irregularly along the body, much shorter than cephalic setae. Amphideal fovea large, round in outline, spirally coiled ventrally in 2.75–3.25 turns.

Buccal cavity narrow, conical, its walls not cuticularised and weakly developed, with three small teeth discernible. Pharynx with transversal muscular striation along its entire length. Pharynx cylindrical, 150 µm long, forming terminal swelling. Nerve ring at 40–50% of pharynx length from anterior end. Opening of secretoryexcretory system situated just posterior to the nerve ring, ventral gland placed posterior of cardia. Cardia round, prominent, surrounded with intestinal tissue.

Reproductive system diorchic, anterior outstretched testis situated on the left of the gut and posterior reflected testis on the right of gut. Spermatozoa oval to round shape. Spicules paired, with a velum, strongly cuticularised, distally acute, proximally slightly cephalated. Gubernaculum with weakly cuticularised, long dorso-caudally directed apophyses. Short sub-ventral setae (2.0 µm long) just anterior to the cloaca. Nine minute mid-ventral supplementary papillae observed in precloacal region. Tail with proximal conical and distal cylindrical parts (latter 67–75% of tail length). Tail with caudal gland. Tail tip slightly swollen, with terminal setae (about 2.0 µm long). Somatic setae on tail arranged as four latero-ventral longitudinal rows on conical part of tail. Three caudal glands and spinneret present.

Cylind- rical part of the tail (%) ) (1 68 n-f 76 72 - 80 - 73 - 72 69 78 67 - 75 76 61 -

c' 11.7 - 15.5 - 13.9 11.7 10.8

11 n-f - 9.7 12.1 10.4 11.5 8.8 - 7.3 - 5.0 5.3 6.3

c - - -

4.5 6 4.5 4.5 4.3 7.3 4.6 4.4 a 50.5 41 36. - - - lοcalities L µm) 40 36 36 - 1379 1442 - 32 37 1720 - 33 - 38 1251 31 1182 variοus (1040 1250 1089 1078 1564 1837 1064 929 - frοm ̸

filipjevi Males Females ♂ ♀ ♂ ♀ ♂ ♀ ♂ ♀ Laimella Locality Black Sea Baltic Sea White Sea East Sea οf, characters Source Filipϳev, 1922 Jensen, 1979 Τchesunοv2000 present paper Key

TABLE. 5 Species name Sabatieria longicaudata Laimella filipjevi Laimella filipjevi Laimella filipjevi Females ( Fig. 7 , Table 4 ). Similar to male. Vulva at mid-body. Didelphic, outstretched, anterior ovary situated on right of gut, posterior on left. Uteri of both gonads packed with spermatozoa.

Remarks. Sabatieria longicaudata Filipjev, 1922 was transferred by Jensen (1979) to the genus Laimella , who renamed it Laimella filipjevi due to the subjective homonymy to Laimella longicauda Cobb, 1920 . Laimella filipjevi was initially discovered in the Black Sea ( Filipjev 1922) and then repeatedly found in Øresund (West Baltic Sea), White Sea (North Russia) and now in the remote area off Korea. All finds were made in sublittoral silt or silty sand. Specimens from the various localities differ only slightly from one another (Table 5), suggesting intraspecific variability and geographical range.

Figures

FIGURE 6. Laimella filipjevi Jensen, 1979 from East Sea, Korea, male 1 in lateral view: A, pharynx; B, head; C, pericloacal and anal region; D, tail; E, entire. Scale bars: 20 µm (A – D) and 50 µm (E).

FIGURE 7. Laimella filipjevi Jensen, 1979 from East Sea, Korea, female 1 in lateral view: A, pharynx; B, head; C, tail; D, vulva; E, entire. Scale bars: 20 µm (A – D) and 50 µm (E).

FIGURE 8. Scanning electron micrographs of Laimella filipjevi Jensen, 1979 from East Sea, Korea: A, male head; B, male mouth and inner labial papillae. Arrows point to three small protuberances of teeth. Scale bars: 2 µm (B) and 5 µm (A).