Egtitus bryophilus Thorne, 1967

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 : 462-466

Egtitus bryophilus Thorne, 1967

( Figures 2A–E and 3A, B )

Present females (n = 5): L = 1.97–2.27 mm; a = 44–51; b = 4.6–5.0; c = 13.6–16.2; ć = 5.4–6.0; V = 49–50%. Present males (n = 5): L = 1.80–2.12 mm; a = 45–56; b = 4.2–4.8; c = 61–72; ć = 0.9–1.0. Female after Thorne (1967): L = 2.0; a = 44; b = 4.0; c = 13; ć = 6.0; V = 50%. Male after Thorne (1967): L = 1.9 mm; a = 48; b = 4.2; c = 72.

General characters of the present specimens

Body in female straight, in male posteriorly ventrally curved when fixed, 41–52 µm (female) or 38–48 µm (male) wide in its middle, moderately tapered towards anterior end. Cuticle practically smooth, 2–3 µm on most body regions. Lip region 15–17 µm wide, offset by a slight depression, lips more or less angular, more conspicuous than usual. Body at posterior end of pharynx 2.1–2.7 times as wide as lip region. Amphids caliciform with apertures about half the corresponding body width.

Labial and dental chambers well separated, the former 10–11 µm, the latter 6–8 µm broad. Onchia simple, denticles not present. Odontostyle 17–19 µm long, 1.1–1.2 times as long as labial diameter, 2.0–2.5 µm thick, thicker than cuticle (1.6–1.7 µm) at the same level; the aperture occupying about two-fifths stylet length. Guiding ring double but thin, 6–7 µm wide, and 14–15 µm from anterior end. Pharynx tripartite, 420–466 µm long, rather suddenly expanded at 53–56% of its length. Medial part 96–98 µm long, 20–22% of total length of pharynx. Pharyngeal gland nuclei difficult to see; D = 55–58% (11–13% of total body length), AS nuclei inconspicuous, PS 1 = 67–70%, PS 2 = 68–72%. Glandularium 180–203 µm long. Cardia conical.

Female

Amphidelphic with well-developed gonads, each branch 6.8–8.2 body widths long or occupying 15–16% of body length. Vulva a small longitudinal slit with inner sclerotization. Vagina 18–20 µm, extending to about 40% of body width. Uterus often packed with sperm. Uterine eggs not observed. Distance between posterior end of pharynx and vulva 1.3–1.5 times as long as pharynx. Rectum 1.4–1.7, pre-rectum 4.2–5.3 times the anal body width long. Vulva–anus distance equal to 5.8–7.2 tail lengths. Tail conical with finely tapered posterior half, 130–158 µm long, occupying 6.2–7.3% of entire length of body.

Male

Diorchic with well-developed, straight testes. Spermatozoa fusiform. Spicula 50–58 µm long. Ventromedial supplements small, often hardly discernible, seven to (mostly) nine in number (7, 8, 8, 9, 9, 9, 9), 10–12 µm apart from one another. Pre-rectum beginning at or before the anteriormost supplement. Tail 25–31 µm long, 1.4–1.6% of entire length of body, bluntly conoid with some small papillae.

Remarks

This is the type species of Egtitus, Thorne (1967) described it from Puerto Rico. The Peruvian specimens correspond well with the morphological and morphometric data given by Thorne, so there is little doubt that the present species is identical to E. bryophilus . Only insignificant differences were found, e.g. in the relative length of the pharynx (b = 4.2–5.0 versus 4.0–4.2), somewhat longer odontostyle (17–19 versus 16 µm) and number of ventromedial supplements (7–9 versus 7); but all of these can be regarded as intraspecific variations.

The main distinguishing features of E. bryophilus are as follows: the body about 2 mm long and less tapered towards anterior end, odontostyle short, pharynx enlarged posterior to its middle, female gonads well developed, vulva longitudinal, male prerectum long, spicula relatively small, ventral supplements moderate in number, female tail about six anal body widths long and male tail bluntly conoid.

Habitat and locality

Wet mosses from a rock in a rain forest, about 200 km west of the town Pucallpa, Coronel Portillo Province, Peru (six females, seven males and three juveniles); collected in November 1971 by J. Balogh .

This is the second occurrence of E. bryophilus which is therefore known to inhabit

Central and South America.

Figures

Figure 2. Egtitus bryophilus Thorne, 1967. (A) Anterior end; (B) medial part of pharynx; (C) vulval region; (D, E) female tails. Scale bars 20 µm.

Figure 3. Egtitus bryophilus Thorne, 1967. (A, B) Posterior end of males. Scale bar 20 µm.