Leptolaimus nonus, 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 : 74-87

Leptolaimus nonus sp. n.

( Figs 28 C–D , 33 ; Table 21)

Type material. Holotype male (slide # Type–8498) and six male and eight female paratypes (slides # Type-8498 - Type-8500) deposited in the invertebrate type collection of the Department of Zoology , Swedish Museum of Natural History, Stockholm, Sweden.

Additional material. Three males and nine females (slides # 131249–131252) deposited in the general invertebrate collection of the Department of Zoology , Swedish Museum of Natural History, Stockholm, Sweden .

Type locality. Algae from 15–55 m deep, Skagerrak off the west coast of Sweden (N 58° 17' 24'', E 11° 10' 48''), 09 August 2011, legit O. Holovachov (seven males and eight females) .

Additional localities. Gravel , mud and algae from 30–70 m deep, Skagerrak off the west coast of Sweden (N 58° 22' 14'', E 11° 05' 00''), 09 August 2011, legit O. Holovachov (two females) ; algae from 20–40 m deep, Skagerrak off the west coast of Sweden (N 58° 21' 49'', E 11° 04' 42''), 09 August 2011, legit O. Holovachov (two males and three females) ; coarse sediment with algae from 45–55 m deep, Skagerrak off the west coast of Sweden (N 58° 17' 32'', E 11° 11' 24''), 09 August 2011, legit O. Holovachov (four females) ; 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) .

Etymology. The specific epithet " nonus " is translated as " the ninth " and refers to the sequential number of the new species described in this publication.

Description. Adult. Body tapering anteriorly in pharyngeal region and posteriorly on tail; 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 1.2–2.0 µm wide at mid-body, without ornamentation. Lateral field present, consists of single ala (two incisures), 1.5–3.0 µm wide at mid-body; originating at level of metacorpus (posterior first body pore) and extending posteriorly to proximal part 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 or procorpus. Labial region rounded, continuous with body contour, lips fused. Inner and outer labial sensilla indistinct. Cephalic sensilla setiform, equal to 40–70% 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 present; excretory pore located posterior to nerve ring. 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 (more curved ventrad in male), elongateconoid, gradually narrowing distally. Three caudal glands present, their nuclei are incaudal. Spinneret functional.

Male. Papillae emerging through 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 weak double dorsal apophyses. Accessory apparatus composed of one midventral precloacal papilliform sensillum located on anterior cloacal lip, four-five midventral evenly spaced tubular supplements extending for 73–123 µm from cloaca towards anterior end; alveolar supplement absents. Tubular supplements weakly arcuate in shape, with dentate tips. Posteriormost tubular supplement 16–32 µm anterior to cloaca, anterior to spicules. Sublateral caudal sensilla present: usually eight (four pairs) caudal setae arranged in two subventral and two subdorsal pairs. Precloacal setae absent. One subventral pair of papilliform sensilla located at the bases of the second (from cloaca) pair of caudal setae.

Aberrant male (#1). Similar to typical males except for the smaller body size and presence of only two midventral tubular supplements extending for 45 µm from cloaca towards anterior end.

Aberrant male (#2). Similar to typical males except for the smaller body size, smaller spicules and absence of tubular supplements.

Female. Reproductive system didelphic, amphidelphic; ovary branches reflexed antidromously. Anterior genital branch 60–98 µm long (equal to 10.9–16.6% of total body length), located on right-hand side of intestine (n=5), posterior genital branch 36–93 µm long (equal to 6.6–16.3% of total body length), located on left-hand side of intestine (n=5). Oviduct a narrow tube. Two offset, oval, sac-like spermathecae located on each (right and left) side of each (anterior and posterior) gonoduct. Spermathecae filled with oval spermatozoa. Uterus a wide and short tube. Vagina straight, 0.2–0.5 times vulval body diameters long; pars proximalis vaginae encircled by single sphincter muscle; pars refringens vaginae present, bacilliform in shape. Vulva right-subventral. Epiptygmata and sensitive structures around vulva (advulval sensilla) absent. Supplements absent. Rectum 1.2–2.0 anal body diameters long; surrounded by three gland-like cells at intestine-rectum junction.

Diagnosis (two aberrant males excluded). Leptolaimus nonus sp. n. is particularly characterised by the 403– 633 µm long body; rounded labial region continuous with body contour; cephalic setae 1.5–3.0 µm long; amphid located 8.0–10.0 µm from anterior end; first body pore located 16.5–29.0 µm from anterior end; lateral field originating 47.0–99.0 µm from anterior end; female without supplements, vagina with bacilliform pars refringens, vulva right-subventral; male with 4–5 tubular and without alveolar supplements, tubular supplements weakly arcuate with dentate tips; spicules arcuate and 17.0–26.0 µm long.

Relationships. Leptolaimus nonus sp. n. is most similar to the population of L. elegans described here in the number of supplements, shape of labial region (without distinct outer labial sensilla) and right-subventral position of vulva. It can however be separated from L. elegans based on the following features: pars refringens vaginae present (vs. absent in L. elegans ), sensilla emerging through body pores are papilliform (vs. setiform in L. elegans ) and precloacal pair of setae in male is missing (vs. present in L. elegans ).

Review of the genus Leptolaimus de Man, 1876

= Aplectus Cobb, 1914 op. Hope & Murphy, 1972

= Boveelaimus Alekseev & Rassadnikova, 1977 ( Alekseev, 1979) op. Holovachov & Boström, 2004

= Dermatolaimus Steiner, 1916 op. De Coninck, 1965

= Halaphanolaimus Southern 1914 op. Holovachov & Boström, 2004

= Polylaimium Cobb, 1920 syn. n.

= Leptolaimus (Alveolaimus) Alekseev & Rassadnikova, 1977 op. Holovachov & Boström, 2004

= Leptolaimus (Boveelaimus) Alekseev & Rassadnikova, 1977 op. Holovachov & Boström, 2004

= Leptolaimus (Tubulaimus) Alekseev & Rassadnikova, 1977 op. Holovachov & Boström, 2004

Diagnosis (emended after Holovachov & Boström, 2010). Cuticule annulated, annulation smooth. Lateral ala present, as a single band of smooth cuticle. Epidermal glands present, opening via body pores in two sublateral rows on each body side. Somatic sensilla present, connected to epidermal glands along the body, their number is species-specific. Labial region rounded or truncate. First annules appear anterior to cephalic setae bases. Sclerotized cephalic capsule absent. Inner labial sensilla indistinct. Outer labial sensilla indistinct or papilliform, located on anterior surface of lips. Cephalic sensilla papilliform or setiform; their bases located anterior to amphids. Subcephalic sensilla absent. Ocelli and deirid absent. Amphidial fovea ventrally unispiral. Secretoryexcretory system: renette cell oval, located along ventral side of cardia and anterior part of intestine; excretory pore opens posterior to nerve ring; excretory canal short, excretory ampulla present. Buccal cavity tubular: cheilostom undifferentiated; gymnostom undifferentiated or short barrel-shaped; stegostom tubular. Pharynx subdivided by breaks in muscular pharyngeal tissue into narrow procorpus, somewhat wider metacorpus, narrow isthmus and basal bulb; muscularized; pharyngeal lumen within bulbus is thicker and more cuticularised than elsewhere along the pharynx; valvular apparatus absent. Cardia enveloped by intestine in its posterior part. Female reproductive system didelphic, amphidelphic; ovary branches reflexed antidromously; spermathecae offset, sac-like; unpaired (two in total) or paired (four in total); located on each side of each gonoduct; uterus short or long; vulva equatorial, midventral or left- or right-subventral; vagina straight, pars proximalis vaginae encircled by a single sphincter muscle; pars refringens vaginae present or absent. Male reproductive system diorchic; testes opposed with anterior testis outstretched and posterior one reflexed; spicules arcuate; gubernaculum rectangular or plate-like, with apophysis. Copulatory apparatus: 2–56 alveolar supplements (present or absent), 1–16 midventral tubular supplements (present or absent); single midventral precloacal papilliform sensillum located on the anterior cloacal lip, sometimes additional midventral precloacal setiform sensillum located between posteriormost supplement and cloacal opening; a pair of precloacal setae and several pairs of subventral and subdorsal caudal setae, unpaired setae may be present. Females may also have either tubular (1–4) or tubular and alveolar supplements. Tail conoid, elongate or subcylindrical. Three caudal glands present, their nuclei are incaudal. Spinneret functional, weakly cuticularised.

Body length 410–970 621–735 430–518 926–1313 1460–1935

a 20–38 38–45 26–35 20–26 32–52

b 4.0–6.3 5.3–6.1 3.8–4.5 4.7–5.4 5.9–7.6

c 5.9–10.4 7.1–9.1 6.9–8.3 10.0–12.7 10.7–14.7

c' (male) 3.6–5.8 4.8 4.3–5.7 2.3–3.0 3.3–4.2

c' (female) 4.0–7.8 7.2–8.7? 3.2–3.3 4.1–5.7

V (%) 45–53 48–50 51–53 48 46–51 Labial region diameter 4.0–8.0 5.0–6.0 4.0–5.0 5.8–6.4 7–13 Cephalic setae length 2.0–4.0 1.5–4.0 2.0–3.0 2.5–3.2 3.5–8.0 Amphid from ant. end 6.5–8.0 8.0–9.0 9–11* 6–7 8.5–11

First body pore from ant. end ~17* 17–24 ~27*? 38–51 Lateral field from ant. end? 46–47?? 72–92 Stoma length 15–21 18–21? 30–32 32–40

Tail length (male) 70–95 76 60–68? 120–150

Tail length (female) 52–98 90–99?? 115–141 Spicule length (along arc) 26–34 16–20 15–16 chord 68–70 47–70 Gubernaculum apophysis dorsal dorsal dorsal dorsal dorsal Shape of alveolar supplements NA NA NA NA NA

Tips of tubular supplements? anchor-like anchor-like bifid or round anchor-like Vagina shape straight straight?? straight Vulva orientation? midventral?? midventral Pars refringens vaginae? present?? absent

Male supplements:

alveolar 0 0 0 0 0

tubular (anterior) 1 1 1 1 1–3 tubular (posterior) 3+1 3+1 4–5 11–13 5– 8 Female supplements:

......continued on the next page Body length 493–800 780–900 600–830 762–965 a 25–38 17–29 21–46 27–45 b 4.1–5.4 4.3–4.6 4.8–5.8 5.6–6.5 c 6.0–8.0 7.8–8.5 6.0–8.0 7.3–10.0 c' (male) 4.2–4.8 4.0–6.1 3.5–9.0 4.3–5.3 c' (female) 5.5–8.3 4.0 4.5–9.0 5.5–6.4 V (%) 49–52 49 50–54 49–52 Labial region diameter 3.5–4 8.0–9.0 4–6 4–6 Cephalic setae length 1.5–4 3–4 2–3 2–3 Amphid from ant. end 8–12 ~18* 5–12 8–14 First body pore from ant. end 24–36 ~59*? 29–39 Lateral field from ant. end 50–75?? 57–67 Stoma length 18–24 30 17–25 17–26 Tail length (male) 76–83 95–110* 80–108 85–117 Tail length (female) 75–93 95* 90–133 90–119 Spicule length (along arc) 20–24 R 39–43/L 48–54 24–29 22–29 Gubernaculum apophysis dorsal dorsal dorsal dorsal Shape of alveolar supplements NA NA NA NA Tips of tubular supplements dentate bifid dentate dentate Vagina shape straight?? straight Vulva orientation right-subventral?? midventral Pars refringens vaginae absent? absent present Male supplements:

alveolar 0 0 0 0

......continued on the next page

Figures

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.

FIGURE 33. Leptolaimus nonus sp. n., holotype male (A–C) and paratype 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.