Egtitus chilenus, 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 : 475-479

Egtitus chilenus sp. nov.

( Figures 8A–E and 9A, B )

Holotype female: L = 2.13 mm; a = 41; b = 4.2; c = 13.2; ć = 5.2; V = 49%.

Paratype females (n = 6): L = 1.80–2.22 mm; a = 39–45; b = 3.8–4.4; c = 14.2–16.0; ć = 4.3–5.3; V = 49–52%.

Paratype males (n = 4): L = 1.87–1.94 mm; a = 42–46; b = 3.8–4.2; c = 60–65; ć = 0.9–1.0.

General characters

Body irregularly curved upon fixation, 42–54 µm wide at middle, moderately tapered towards anterior end. Cuticle practically smooth, 2 µm thick on most body regions. Lip region slightly offset by depression, 18–19 µm wide, lips amalgamated. Body at posterior end of pharynx 2.2–2.8 times as wide as lip region. Amphids caliciform with apertures nearly half as wide as corresponding body.

Labial chamber 11–12 µm, dental chamber 8–9 µm broad, the latter devoid of denticles. Onchia simple. Odontostyle 20–23 µm long, 1.1–1.2 times longer than labial width, 2.2–2.5 µm thick, distinctly thicker than cuticle (1.3–1.4 µm) at the same level. The aperture occupying about two-fifths of stylet length. Guiding ring thin, 7 µm wide, 15–17 µm from anterior body end. Pharynx tripartite, 450–550 µm long, always enlarged before its middle, at 42–46%. Medial part short, 70–75 µm, 14–15% of the length of pharynx. As usual in the genus, pharyngeal nuclei less conspicuous. D = 44–49%, AS nuclei indistinct, PS 1 = 72–76%, PS 2 = 74–78%. Glandularium 240–276 µm long.

Female

Reproductive system amphidelphic, genital branches moderately developed, each 4.2–6.4 times as long as mid-body diameter or occupying 12.6–13.6% of body length. Vulva a short longitudinal slit with well sclerotized inner pieces. Vagina 22–26 µm long, about half the corresponding body width. No mature eggs. Distance between proximal end of pharynx and vulva 1.0–1.2 times as long as pharynx. Rectum 1.2–1.5, pre-rectum 2.6–4.3 times the anal body width in length. Vulva–anus distance equal to 5.6–7.4 tail lengths. Tail conical, gradually attenuated to a sharp tip, 114–160 µm long.

Male

Diorchic, testes well developed with fusiform spermatozoa. Spicula 50–54 µm long, dorylaimoid. Ventromedial supplements 10 or 11 (10 in two males and 11 in five males), small. Pre-rectum beginning anterior to the first supplement. Tail 28–32 µm long, occupying 1.5–1.6% of total body length.

Diagnosis and relationships

Body slender, on average 2.06 mm long (female), moderately narrowed on anterior region, lip region narrow, odontostyle fairly short, pharynx enlarged well before its middle, vulva longitudinal, male supplements 10–11, female tail straight, 4–5 anal body widths long.

As already mentioned before, the majority of Egtitus species are distributed in Asia and Australia (Australasia). Three species are known to occur in the American continent, more specifically in Central and South America, namely E. bryophilus , E. elaboratus and E. surinamensis . In certain respects (body length, length and shape of female tail, comparatively short odontostyle) E. chilenus sp. nov. is closely related to E. bryophilus Thorne, 1967 . It differs from Thorne’s species by the unusually long cylindrus (54–58% versus 44–47% of pharyngeal length; a constant character!), the longer odontostyle (20–23 versus 17–19 µm) and the greater number of ventromedial supplements (10–11 versus 7–9). Egtitus chilenus sp. nov. differs also from the other two American species; from E. elaboratus by the longer body (1.8–2.2 versus 1.7–1.8 mm), narrower lip region (18–19 versus 22–24 µm) and long expanded section of the pharynx (cylindrus); from E. surinamensis (which is inadequately described) by the longer body (1.9 versus 1.4 mm, males) and the higher number of supplements (10–11 versus 7).

Type specimens

Holotype female on slide no. 14518. Paratypes: 13 females, seven males and two juveniles. Deposited at the Department of Systematic Zoology of the ELTE University , Budapest .

Type habitat and locality

Soil with detritus from a Nothofagus (Southern beech) forest, Quellón, Southern Chiloé Island, Los Lagos Region, Chile; collected in February 2001 by Cs. Csuzdi and L. Hufnágel .

Etymology

Named after the country where it was found, Chile.

Figures

Figure 8. Egtitus chilenus sp. nov. (A) Anterior end; (B) medial part of pharynx; (C) vulval region; (D, E) female tails. Scale bars 20 µm.

Figure 9. Egtitus chilenus sp. nov. (A, B) Posterior end of male. Scale bars 20 µm.