Leptolaimus macer Lorenzen, 1972

Holovachov, Oleksandr & Boström, Sven, 2013, Swedish Plectida (Nematoda). Part 4. The genus Leptolaimus de Man, 1876, Zootaxa 3739 (1), pp. 1-99 : 63-65

Leptolaimus macer Lorenzen, 1972

( Figs 27 , 28 A–B ; Table 18)

Material examined. Five males and 11 females (slides # 130723–130725) deposited in the general invertebrate collection of the Department of Zoology , Swedish Museum of Natural History, Stockholm, Sweden .

Habitat and locality. Muddy sand from 8–15 m deep, Gullmarn Fjord near Fiskebäckskil, Sweden (N 58° 15' 09'', E 11° 27' 54''), 11 August 2011, legit O. Holovachov (five males and 11 females) .

Description. Adult. Body tapering anteriorly in pharyngeal region and posteriorly on tail; ventrally curved or coiled 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 1.6–2.0 µm wide at mid-body, without ornamentation. Lateral field present, consists of single ala (two incisures), 1.5–2.0 µm wide at mid-body; originating at level of posterior part of metacorpus (close to third body pore) and extending posteriorly to distal part of tail. Prominent body pores in sublateral position at both sides of lateral field present, arising from oval lateral epidermal gland cells; usually four pairs of body pores are present along pharyngeal region; several body pores scattered over rest of the body. Anteriormost body pore located at level of stoma, just posterior to amphid. Labial region rounded, continuous with body contour, lips fused. Inner and outer labial sensilla indistinct. Cephalic sensilla setiform, equal to 130–170% of labial region diameter. Subcephalic and cervical sensilla and ocelli absent. Amphidial fovea round, 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. Long setae emerging through first, second and fourth pairs of body pores. Reproductive system diorchic; anterior testis outstretched; posterior one reflexed. Spicules paired, symmetrical, with arcuate subcylindrical calamus and ovoid manubrium. Gubernaculum plate-like, with arcuate dorsal apophysis. Accessory apparatus composed of one midventral precloacal papilliform sensillum located on anterior cloacal lip, seven unevenly spaced midventral tubular supplements extending for 227–242 µm from cloaca towards anterior end; alveolar supplements absent. There is a distinct gap between the second (from cloaca) and the third (from cloaca) tubules. Tubular supplements sickle-shaped, with truncate tips. Posteriormost tubular supplement 32.0–34.0 µm anterior to cloaca, anterior to spicules. Sublateral precloacal and caudal sensilla present: one right precloacal setae at level of spicules and usually seven caudal setae arranged subventrally and subdorsally.

Female. Reproductive system didelphic, amphidelphic; ovary branches reflexed antidromously. Anterior genital branch 78–131 µm long (equal to 9.8–16.2% of total body length), located on right-hand (n=6) or left-hand (n=1) side of intestine, posterior genital branch 71–135 µm long (equal to 9.1–16.6% of total body length), located on left-hand (n=6) or right-hand (n=1) side of intestine. 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 filled with oval spermatozoa. Uterus a wide and short tube. Vagina straight, 0.3 times vulval body diameters long; pars proximalis vaginae encircled by single sphincter muscle; pars refringens vaginae absent. Vulva rightventrosublateral. Epiptygmata and sensitive structures around vulva (advulval sensilla) absent. Supplements absent. Rectum 1.4–2.0 anal body diameters long; surrounded by three gland-like cells at intestine-rectum junction.

Diagnosis (supplemented with literature data). Leptolaimus macer is particularly characterised by the 698–862 µm long body; rounded labial region continuous with body contour; cephalic setae 6.0–8.0 µm long; amphid located 8.5–13.0 µm from anterior end; first body pore located 14.0–20.0 µm from anterior end; lateral field originating 66.0–91.5 µm from anterior end; female without supplements, vagina without pars refringens, vulva right ventrosublateral; male with seven tubular and without alveolar supplements, tubular supplements sickleshaped with blunt tips; spicules arcuate and 15.0–18.5 µm long.

Remarks. Current specimen agrees well with the type population of L. macer in general morphology, measurements, shape, number and position of tubular supplements, shape of spicules and gubernaculum. Females are described for the first time in this species.

Figures

FIGURE 27. Leptolaimus macer Lorenzen, 1972, 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.

FIGURE 28. Leptolaimus macer Lorenzen, 1972 (A–B) and Leptolaimus nonus sp. n. (C–D). A, C: Entire female; B, D: Entire male. Scale bar: A–D = 50 µm.