Chordodes digitatus Linstow, 1901

De Villalobos, Cristina, Zanca, Fernanda & Schmidt‐Rhaesa, Andreas, 2007, Revision of the genus Chordodes (Gordiida, Nematomorpha) from Africa-III: ultrastructural redescription of Chordodes capensis Camerano, 1895, C. clavatus Linstow, 1906, C. digitatus Linstow, 1901, C. tuberculatus Linstow, 1901, and reinterpretation of C. ibembensis Sciacchitano, 1958 and C. uncinatus Sciacchitano, 1958, Journal of Natural History 41 (45 - 48), pp. 2775-2788 : 2782-2785

Chordodes digitatus Linstow, 1901

( Figures 4 , 5 )

Chordodes digitatus Linstow 1901, p 417 , Figure 18.

Material

Holotype: 1 „, Tanzania, Unyika plateau ( ZMB Vermes 4017) . Paratypes: 2♀♀, from type locality ( ZMB Vermes 4017a) .

Material examined. Holotype and paratypes, SEM midbody. Holotype, SEM posterior end.

Host

Unknown.

Description

The body colour of the male is dark brown. The body length is 110 mm and 0.5 mm in diameter. The anterior end is tapered and a dark collar is lacking. The posterior end is undivided and has a median ventral groove ( Figure 4A ). The cloacal opening lies on a central cuticular protuberance and is situated ventrally at about 210 mm from the posterior margin of the animal. The cloacal opening is oval (32.4 mm in length) and surrounded by circumcloacal spines. These spines are about 12.7 mm long and unbranched. Lateral to the cloacal opening are two straight rows of bristles ( Figure 4A, B ). They reach up to 79 mm in length. Around the cloacal opening, the cuticle is smooth and contains scattered small bristles spreading over the ventral side ( Figure 4A ).

The cuticle of the male contains five areolar types. Simple areoles are the most abundant, they are rounded or oval in shape, low (6.5 mm), and have a smooth surface. Irregular minute projections are distributed on the apical surface ( Figure 5A ). Among these are scattered areoles with the same shape but with a tubercle on top (tubercle areoles). The tubercle is about 4.5 mm long. Another type of areole has a solid spine (thorn) on top (thorn areoles). The thorn is longer than the tubercles (7.6 mm) and originates in an eccentric depression in the areole, which is round or horseshoe-like in shape ( Figure 5A, B ). Clusters of 11–13 of circumcluster areoles (8.6–9.5 mm high) with short filaments on the apex surround three crowned areoles ( Figure 5B ). Crowned areoles (9.6–10.5 mm high) have extremely short apical filaments. The interareolar furrow is wide (2.7–6.4 mm) and structured into cord-like ridges.

The female body length varies between 120 and 140 mm, the diameter varies between 0.4 and 0.8 mm. The anterior end is tapered, a white tip or dark collar are not present. The body colour is brown.

The cuticle contains the same five types of areoles as in the male, but on both sides along the ventral midline there is another type of crowned areole ( Figure 5C ). These crowned areoles have a crown of long filaments (78.1 mm) on top and occur in clusters of three and are surrounded by 9–10 circumcluster areoles.

Comments

In the original description of Chordodes digitatus, Linstow (1901) provided measurements of the specimens without specifying to which sex each corresponded. Camerano (1915) mentioned this fact, noting the importance of this information. The present information by SEM reveal that the type specimens of C. digitatus correspond to one male and two females. Linstow (1901) described the cuticle of C. digitatus with three areolar types: types 1 and 2 correspond to the simple and tubercle areoles, respectively, in the present reinvestigation. The areoles described by Linstow (1901) as type 3 are considered to correspond to circumcluster and crowned areoles.

Figures

Figure 4. Chordodes digitatus, holotype, SEM male posterior end. (A) View of the cloacal opening (c) lying on the central cuticular protuberance and surrounded by circumcloacal spines. Lateral to the cloacal opening are two rows of bristles (the bristlefield, arrow); (B) detail of the posterior end. Scale bars: 50 mm (A); 20 mm (B).

Figure 5. Chordodes digitatus. (A, B) SEM male midbody cuticle: (A) cuticle with simple (1), tubercle (2) and thorn areoles; (B) midbody cuticle showing thorn areole (3) and clusters of crowned areoles (4) surrounded by circumcluster areoles (5). (C) SEM of female longitudinal ventral groove: thorn areole (3) and crowned areoles with long filaments (6). Scale bars: 10 mm.