Deontolaimus cangioensis, Tu, Nguyen Dinh, Thanh, Nguyen Vu, Hoang, Lai Phu & Saint-Paul, Ulrich, 2016

Tu, Nguyen Dinh, Thanh, Nguyen Vu, Hoang, Lai Phu & Saint-Paul, Ulrich, 2016, Two new species of the genus Deontolaimus de Man, 1880 (Nematoda: Leptolaimidae) from mangrove ecosystems of Vietnam, Zootaxa 4205 (1), pp. 73-80 : 76-79

Deontolaimus cangioensis sp. n.

( Table 2, Figure 3 , 4 )

Description. Males: (mainly referring to holotype). Body length 607 µm, maximum diameter 20 µm. Cuticle finely annulated with a lateral field visible from just behind the base of the pharynx to its terminus in the tail region. Head with four small cephalic setae (R3) 2 µm long (0.25 hd), sensillae of R1, and R2 minute papilliform and difficult to detect. Amphids one-turn spiral, 2 µm wide (0.25 hd), and located at the level of the cephalic setae (R3) from anterior end. Dorsal buccal tooth 14µm long (2 hd), strongly cuticularised at the tip. Pharynx cylindrical, only weakly enlarged at posterior end. Ventral gland or its exit pore not seen. Testes two, outstretched and directed forward, located on the left side of intestine. Spicules 26 µm (1.5 abd) measured on the chord, slender, regularly bent with proximal half swollen. Gubernaculum small with curved dorso-caudal apophysis. 31 simple, cup-shaped precloacal supplements beginning posterior to the end of the dorsal tooth and extending to middle body position (60% of body length from anterior end). Tail conical 62 µm long (3.7 abd). Tail tip very strongly cuticularised and unstriated. There are two minute post cloacal setae, the first located 26 µm (1.5 abd) posterior to cloaca, and the second 0.5 cbd from the first. Three caudal glands.

Females: (paratypes). Similar to males in general appearance. Body length averaging 654 µm (505-774µm) Cuticle annulated with 3 weak lateral lines, visible at the middle of the body. The maximum diameter averages 20 µm (14-23 µm). Dorsal tooth averaging 11 µm (9-14 µm) in length, a little smaller than in male. Amphids located at nearly the same position as in male. Ovaries opposed and reflexed antidromously, with the anterior ovary on the right side of the intestine and the posterior ovary on the left side. Vulva at 50-52% of body length. Tail conical with tail tip pointed. Tubular structures (supplements) never seen in females.

Remarks. The new species resembles D. papillatus de Man, 1880 in body shape, especially in the tail region and tail terminus. It differs from D. papillatus in the shape of gubernaculum: simple plate-like in D. papillatus vs complicated plate-like with dorsally curved apophyses in D.cangioensis .

Type material. Holotype (1♂), slide VNMN.0057. Paratypes: 2 ♂, VNMN. 0058 - 59, 4♂, VNMN.0065 – 68, deposited at the Vietnam National Museum of Nature , Vietnam.

Etymology. The species name refers to the type locality: the Can Gio mangrove forest.

Characteristic holotype ♂ 1 Paratypes Paratypes

♂2 ♂ 3 ♀1 ♀2 ♀3 ♀ 4 L 607 598 468 737 774 600 505 a 30.3 48.2 37.8 31.4 35.4 30.3 37.3 b 4.2? 4.2 4.9 5.3 4.4 4.7 c 9.7 9.5 10.0 11.6 10.3 8.7 10.1 c’ 3.7 6.3 4.4 4.6 5.1 5.1 5.3 spic. 26 not clear not clear

sup. 31 32 35

V% 52 51 51 50 Key to the species of the genus Deontolaimus (Based on Holovachov & Bostrom, 2015)

1. Anterior ovary reduced, posterior ovary functional................................................ D. monhystera

- Both ovaries equally developed, functional (if known)........................................................2

2. Males with caudal alae at level with cloaca....................................................... D. prytherchi

- Males without caudal alae at level with cloaca.............................................................. 3

3. Cephalic setae located anterior to amphid according to illustration................................. D. pontollittoralis

- Cephalic setae located at level with or posterior to amphid.................................................... 4

4. Excretory pore located at level with onchiostyle or anterior-most part of intestine.................................. 5

- Excretory pore located at level with nerve ring............................................................. 6

5. Body 1.2–1.7 mm long, excretory pore located 9–17 µm posterior to cephalic setae........................ D. catalinae

- Body 0.7–0.8 mm long, excretory pore located at level with cephalic setae bases........................... D. parvus

6. Amphid multispiral...................................................................................7

- Amphid unispiral.....................................................................................9

7. Cephalic setae located at level with amphid base; tail very long (c' = 9–12).............................. D. praedator

- Cephalic setae located far posterior to amphid base; tail short (c' = 2.5–5.5).......................................8

8. Cephalic setae short (6.5–8.5 µm); tail longer (c' = 3.3–5.4).......................................... D. uniformis

- Cephalic setae long (18 µm); tail shorter (c' = 2.5–3.4).................................................. D. exilis

9. Cephalic setae located far posterior to amphid base.........................................................10

- Cephalic setae located at level with amphid base........................................................... 11

10. Spicules 24–30 µm long..................................................................... D. longicauda

- Spicules 20–21 µm long.................................................................. D. trituberculatus

11. Body over 2.5 mm long (2.7–3.2 mm); spicules over 60 µm long (63–65 µm).............................. D. guillei

- Body less than 2.5 mm long (0.5–2.4 mm); spicules less than 60 µm long (20–59 µm)..............................12

12. Cephalic setae relatively long (=5–8 µm, measured from illustrations)..........................................13

- Cephalic setae relatively short (=1–2 µm).................................................................14

13. Tail relatively long (c' = 6), spinneret broad conoid, not offset from............................... D. cylindricaudatus

- Tail relatively short (c' = 3.8–4.6), spinneret narrow and curved dorsad, sharply offset from tail....... D. lorenzeni nom. n.

14. Alveolar supplements extend along entire body almost to cloaca............................................... 15

- Alveolar supplements present in pharyngeal region only.....................................................17

15. Gubernaculum simple plate-like without apophyses, body over 1.0 mm long; spicules over 40 µm long....... D. paraguillei

- Gubernaculum complicated with dorsal curve apophyses, body less than 1.0 mm long; spicules less than 40 µm long......16

16. Spicules 20 µm long; 47 (47- 49 supplements); c’ = 7.3......................................... D. mangrovi sp. n.

- Spicules 26 µm long; 31 (32- 359 supplements); c’ = 3.7...................................... D. cangioensis sp. n.

17. Body over 1.5 mm long (1.6–2.4 mm); spicules over 50 µm long (53–59 µm).............................. D. tardus

- Body less than 1.5 mm long (0.5–1.1 mm); spicules less than 40 µm long (20–35 µm)..............................18

18. Alveolar supplements very distinct along the pharyngeal region...................................... D. papillatus

- Alveolar supplements small and difficult to discern.................................................... D. timmi

Figures

FIGURE 3. Deontolaimus cangioensis sp. nov., male. A. Anterior end; B. Entire male; C. Tail.

FIGURE 4. Deontolaimuscangioensis sp. nov., female. A. Anterior end; B. Entire female; C. Vulva region; D. Tail.