Egtitus remotus, Andrássy, 2012

Andrássy, István, 2012, On the “ Paractinolaimus ” genus group (Nematoda: Actinolaimidae), with description of five new and two rare species of Egtitus Thorne, 1967, Journal of Natural History 46 (7 - 8), pp. 453-494 : 472-475

Egtitus remotus sp. nov.

( Figures 6A–E and 7A, B )

Holotype female: L = 2.39 mm; a = 40; b = 3.6; c = 28; ć = 2.6; V = 51%.

Paratype males (n = 4): L = 2.18–2.58 mm; a = 41–50; b = 3.6–4.0; c = 55–76; ć = 0.8–0.9.

General characters

Body ventrally curved upon fixation, especially in its posterior third, strongly tapered toward anterior end, 52–60 µm wide at mid-region. Cuticle smooth, 2–3 µm thick on most body regions. Lip region comparatively small, 15–17 µm wide, separated by a weak depression, lips amalgamated. Body at posterior end of pharynx 3.1–3.7 times wider than lip region. Amphids caliciform with apertures nearly half as wide as corresponding body.

Labial chamber less separated, wider (9–11 µm) than dental chamber (8–9 µm). The latter slightly ribbed, without denticles. Onchia simple. Odontostyle 20–22 µm long, 1.2–1.4 times as long as lip region width, 1.6–1.8 µm thick, slightly thicker than cuticle at the same level. Guiding ring double but thin, 6.0–6.5 µm wide, 14–16 µm from anterior end of body. Pharynx tripartite, 590–690 µm long, in three of the five specimens occupying more than one-quarter (28%) of body length, expanded at 51–54% of its length. Medial part comparatively short, 80–86 µm, occupying 13–14% of entire length of pharynx. Pharyngeal nuclei rather obscure, D = 52–56% (14–15% of total body length), AS nuclei indistinct, PS = 72–74%. Glandularium 280–318 µm long. Posterior end of pharynx with a shallow disc, cardia conical. Intestine with wide lumen.

Female

Amphidelphic with short genital branches, each 4.4 body widths long or occupying about 10% of body length. Ovaries extending one-third distance from genital tip to vulva. Vulva longitudinal with well sclerotized inner pieces. Vagina 26 µm, occupying half the body width. Uteri proximally broad, distally narrow. Mature eggs not observed. Distance between posterior end of pharynx and vulva shorter (0.8 times) than pharynx. Rectum 1.4, pre-rectum 2.3 anal body widths long. Vulva–anus distance equal to 12.6 tail lengths. Tail short, 86 µm or 3.6% of entire length of body, conical with very sharp tip.

Male

Diorchic with well-developed testes packed with fusiform spermatozoa. Spicula 68–70 µm long, nearly twice as long as tail. Ventromedial supplements small, 10 (two males) or 11 (two males), the posteriormost well before the spicula. Pre-rectum beginning within the range of supplements. Tail 30–40 µm long or occupying 1.2–1.8% of total body length, shorter (0.8–0.9 times) than anal body diameter, conoid with narrowly rounded tip.

Diagnosis and relationships

Size ranging between 2.2 and 2.6 mm, body strongly tapered in its anterior quarter (neck region), lip region small, odontostyle of medium length, longer than lip region width, pharynx enlarged somewhat posterior to its middle, female gonads short, vulva longitudinal, male supplements 10–11, female tail short with sharp tip, male tail narrowly rounded.

By virtue of the short female tail, E. remotus sp. nov. can be compared with E. conicaudatus from Japan and E. shillongensis from India. It differs from E. conicaudatus by the longer body (2.2–2.6 versus 1.7–2.0 mm), much narrower lip region (16–18 versus 22–25 µm wide), odontostyle longer than lip width (versus about as long as lip width), and by the very sharply pointed tail. The new species differs from E. shillongensis by the much narrower lip region (16–18 versus 23–25 µm wide), shorter odontostyle (19–21 versus 24–26 µm) and shorter tail (86 versus 125–132 µm).

Egtitus remotus sp. nov. can be differentiated from the other Papuan species as follows. From E. neocyatholaimus in having a shorter odontostyle (19–21 versus 22–24 µm), fewer supplements (10–11 versus 12–13) and a much shorter female tail (2.6 versus 8.0 anal body diameters); from E. biformis sp. nov. in having a shorter odontostyle (19–21 versus 25–26 µm) and a shorter tail (2.6 versus 6–7 anal body diameters); from E. longicaudatus sp. nov. by the much shorter female tail (86 versus 380 µm).

Type specimens

Holotype female on slide no. 13000. Paratypes: four males. All in the collection of the Department of Systematic Zoology of the ELTE University , Budapest .

Type habitat and locality

Moss growing on the trunk of a Podocarpus sp. , Kambugomambuno, Mount Wilhelm, Papua New Guinea; collected in August 1968 by J. Balogh and I. Loksa.

Etymology

Latin remotus = remote, concerning the distant Far Eastern occurrence of this species.

Figures

Figure 6. Egtitus remotus sp. nov. (A) Anterior end; (B) medial part of pharynx; (C) cardial region; (D) vulval region; (E) female tail. Scale bars 20 µm.

Figure 7. Egtitus remotus sp. nov. (A, B) Posterior end of male. Scale bar 20 µm.