Leptolaimus lorenzeni ( Boucher & de Bovée, 1972 ) Holovachov & Boström, 2013

Holovachov, Oleksandr & Boström, Sven, 2013, Swedish Plectida (Nematoda). Part 4. The genus Leptolaimus de Man, 1876, Zootaxa 3739 (1), pp. 1-99 : 43-46

Leptolaimus lorenzeni ( Boucher & de Bovée, 1972) comb. n.

( Fig. 18 C–D , 19 ; Table 12)

Material examined. One male and two females (slides # 130564–130566) deposited in the general invertebrate collection of the Department of Zoology , Swedish Museum of Natural History, Stockholm, Sweden .

Habitat and locality. Soft mud from 30 m deep, Gullmarn Fjord near Fiskebäckskil, Sweden (N 58° 15' 25'', E 11° 27' 30''), 11 August 2011, legit O. Holovachov (one male and one female), soft mud from 44 m deep, Gullmarn Fjord near Fiskebäckskil, Sweden (N 58° 15' 37'', E 11° 27' 43''), 11 August 2011, legit O. Holovachov (one female) .

Description. Adult. Body tapering anteriorly in pharyngeal region and posteriorly on tail; straight or ventrally curved upon fixation, more strongly curved ventrad in posterior part in males. Maximum body diameter at vulva in female; male body more cylindrical. Cuticle annulated; annuli 2.0 µm wide at mid-body, without ornamentation. Lateral field present, consists of single ala (two incisures), 1.5 µm wide at mid-body; originating at level of metacorpus (posterior to first body pore) and extending posteriorly to middle of tail. Prominent body pores in sublateral position at both sides of lateral field present, arising from oval lateral epidermal gland cells; usually three pairs of body pores are present along pharyngeal region; numerous body pores scattered over rest of the body. Anteriormost body pore located at level of stoma base. Labial region rounded, continuous with body contour, lips fused. Inner and outer labial sensilla indistinct. Cephalic sensilla setiform, equal to 40% of labial region diameter. Subcephalic and cervical sensilla and ocelli absent. Amphidial fovea rounded, located at level of middle of stoma. Nerve ring surrounding pharynx at level of anterior part of isthmus. Hemizonid not seen. Secretory-excretory system indistinct. Buccal cavity uniformly tubular: cheilostom and gymnostom short, undifferentiated; stegostom tubular, with uniformly thickened lumen. Pharynx muscular, cylindrical anteriorly, with distinct oval basal bulb; valvular apparatus absent. Anterior cylindrical part of pharynx subdivided by breaks in muscular pharyngeal tissue into cylindrical procorpus, cylindrical metacorpus and narrow isthmus. Pharyngeal glands and their orifices indistinct. Cardia cylindrical, its posterior part embedded in intestine. Tail similar in shape in both sexes (shorter and more curved ventrad in male), elongate-conoid, gradually narrowing distally. Three caudal glands present, their nuclei are incaudal. Spinneret functional.

Male. Three pairs of long setae emerging through first, second and third pairs of body pores. Reproductive system diorchic; anterior testis outstretched; posterior one reflexed. Spicules paired, symmetrical, with arcuate subcylindrical calamus and conoid manubrium. Gubernaculum plate-like, with dorsal apophysis. Accessory apparatus composed of one midventral precloacal papilliform sensillum located on anterior cloacal lip, five unevenly spaced midventral tubular supplements extending for 414 µm from cloaca towards anterior end; alveolar supplements absent. Tubular supplements weakly arcuate, almost straight in shape, with anchor-like tips; one supplement located just posterior to cardia, and four supplements along the posterior body part unevenly spaced, the distance between third posteriormost and fourth posteriormost supplement is twice as big as the distance between second posteriormost and third posteriormost supplements. Posteriormost tubular supplement 26.0 µm anterior to cloaca, anterior to spicules. Sublateral precloacal and caudal sensilla present: two (one pair) precloacal setae at level of cloaca and at least six (three pairs) caudal setae arranged in two subventral and one subdorsal pairs.

Female. Reproductive system didelphic, amphidelphic; ovary branches reflexed antidromously. Anterior genital branch 68–70 µm long (equal to 9.7–10.3% of total body length), located on right-hand side of intestine (n=2), posterior genital branch 75 µm long (equal to 10.7–11.0% of total body length), located on left-hand side of intestine (n=2). Oviduct a narrow tube. One offset, oval, sac-like spermatheca located on right side of anterior gonoduct and one on left side of posterior gonoduct. Spermathecae often filled with oval spermatozoa. Uterus a wide tube. Vagina straight, 0.3 times vulval body diameters long; pars proximalis vaginae encircled by single sphincter muscle; pars refringens vaginae present, drop-shaped. Vulva midventral. Epiptygmata and sensitive structures around vulva (advulval sensilla) absent. Two tubular supplements present: one anterior located along the anterior part of intestine, and one posterior located in front of anus, 24–28 µm anterior to anal opening. Rectum 1.3 anal body diameters long; surrounded by three gland-like cells at intestine-rectum junction.

Diagnosis (supplemented with literature data). Leptolaimus lorenzeni is particularly characterised by the 621– 735 µm long body; rounded labial region continuous with body contour; cephalic setae 1.5–4.0 µm long; amphid located 8.0–9.0 µm from anterior end; first body pore located 16.5–24.0 µm from anterior end; lateral field originating 46.0–47.0 µm from anterior end; female with two tubular supplements (one just posterior to cardia and one in front of anus), vagina with drop-shaped pars refringens, vulva midventral; male with five tubular and without alveolar supplements, tubular supplements weakly arcuate with anchor-like tips, one just posterior to cardia and four unevenly spaced in front of cloaca; spicules arcuate and 16.0–20.0 µm long.

Remarks. Current specimens agree well with the type specimens in general morphology, number and arrangement of tubular supplements both in females and males, etc., the only difference being length of spicules (20.0 µm in recent male vs. 16 µm in the male described by Lorenzen). Unfortunately, the description of this species by Lorenzen (1972b) is not detailed enough to allow any further comparison.

Figures

FIGURE 18. Leptolaimus quintus sp. n. (A–B), Leptolaimus lorenzeni (Boucher & de Bovée, 1972) comb. n. (C–D) and Leptolaimus venustus Lorenzen, 1972 (E–F). A, C, E: Entire female; B, D, F: Entire male. Scale bar: A–F = 50 µm.

FIGURE 19. Leptolaimus lorenzeni (Boucher & de Bovée, 1972) comb. n., male (A–C) and female (D–E). A: Anterior end, surface view; B: Pharyngeal region, median section; C: Male posterior region; D: Female tail; E: Female reproductive system (anterior part). Scale bar: A–E = 20 µm.