Egtitus africanus, 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 : 470-472

Egtitus africanus sp. nov.

This species is based on “ Neoactinolaimus elaboratus ” as described by Heyns and Argo (1969) on the basis of several female and male specimens collected from various localities in South Africa. The other African collections, by Coomans (1966) from Congo and by Williams (1959) from Mauritius, might also contain this species.

Egtitus africanus sp. nov. is characterized as follows. Female holotype from Port St Johns , Transkei , South Africa: L = 1.86 mm; a = 49; b = 3.7; c = 12; ć = 6.2; V = 51%. Females from South Africa (n = 14): L = 1.60–2.19 mm; a = 38–57; b = 3.5–4.5; c = 13–22; V = 52–56%. Females from Congo (n = 2): L = 1.43–1.74 mm; a = 36–42; b = 3.5–3.9; c = 12–19; ć = 4.5–5.5; V = 53–54%. Females from Mauritius (n =?): L = 1.5–1.7 mm; a = 37–41; b = 3.4–4.0; c = 16; ć = 4.8; V = 55%. Males from South Africa (n = 10): L = 1.56–1.85 mm; a = 30–61; b = 3.2–4.1; c = 61–76 .

General characters

Body slightly ventrally curved when fixed, slender, about 40–50 µm wide at middle. Cuticle practically smooth (very finely annulated), 1.5 µm thick in the mid-body. Lip region rounded, distinctly swollen, 17–20 µm wide, wider than adjacent neck region. Lips completely amalgamated. Amphid aperture about half as wide as corresponding body.

Labial chamber wider than dental chamber, the latter slightly ribbed, but without denticles. Vestibular ring moderately corrugated. Onchia simple. Odontostyle straight, 17–20 µm long, as long as or a little shorter than labial diameter, its aperture occupying nearly half its length. Pharynx 420–550 µm long, at 48–52% enlarged. As for the pharyngeal nuclei, D = 54–56%, AS nuclei obscure, PS = 82–85%. Rectum 1.2–1.4, pre-rectum 2.5–3.6 times the anal body diameter long. A small mucro occurs in the anterior slender part of pharynx.

Female

A detailed description of the female gonad is given by Coomans (1965). Amphidelphic. Vulva apparently longitudinal with sclerotized inner lips, sunken in a depression. Cuticle near vulva occasionally with some weak folds. Uterus relatively long, ovaries however short. Female tail 90–150 µm long, straight or slightly bent dorsally in its posterior half, ending in a sharp terminus.

Male

Diorchic. Spicula 43–50 µm long, longer than tail. Ventromedial supplements small, arranged in a series, spaced, seven to nine in number. Male tail bluntly rounded, dorsally convex, shorter than anal body width.

Diagnosis and relationships

Medium-sized species (on average 1.76 mm) with swollen head, large amphids, comparatively simple buccal structure, straight and short odontostyle, long stylet aperture, pharynx at its middle enlarged, longitudinal and internally sclerotized vulva, relatively few and well-spaced male supplements, and with medium long, sharply pointed female tail.

As stated above, E. africanus sp. nov. most closely resembles E. elaboratus ( Cobb, 1906) Thorne, 1967 , but can be differentiated from it by the narrower lip region (17–20 versus 22–24 µm), shorter and straight odontostyle (17–20 versus 22 µm, sinuate), and maybe by the very sharply tipped female tail (versus finely rounded on tip).

Egtitus africanus sp. nov. also resembles E. bryophilus Thorne, 1967 , but differs from it by having a shorter odontostyle (as long as or somewhat shorter versus longer than lip region width), sharply pointed female tail (versus finely rounded on tip) and male tail more or less hemispherical (versus bluntly conoid). Moreover, the newly named species has an African distribution, whereas its two congeners mentioned above inhabit Hawaii and Puerto Rico, respectively, on almost opposite sides of the globe.

Finally, E. africanus sp. nov. when compared with the other African species of the genus, E. prodenticulatus ( Heyns and Argo, 1969) comb. nov., is differentiated by the much narrower lip region (17–20 versus 25–28 µm) and the distinctly shorter odontostyle (17–20 versus 27 µm).

Type specimens

Holotype female from Port St Johns . Additional specimens: several females and males from various localities in South Africa (see Heyns and Argo, 1969, p. 218).

Type habitat and locality

Indigenous forest on Mount Thesiger, Port St Johns, Transkei, South Africa. In the collection of the Plant Protection Research Institue, Pretoria, South Africa.

Etymology

The epithet underlines the African occurrence of this species.