Bradynectes scilliensis, Faubel & Warwick, 2005

Faubel, A. & Warwick, R. M., 2005, The marine flora and fauna of the Isles of Scilly: Free-living Plathelminthes (‘ Turbellaria’), Journal of Natural History 39 (1), pp. 1-45 : 16-18

Bradynectes scilliensis sp. nov.

( Figure 3 )

Material examined

HOLOTYPE: Sites 2a, 2b: two specimens, in squash preparation, stored on CD-ROM: 2003.5.22.3; WM: 2003.5.22.3.

Etymology

The specific epithet refers to the Isles of Scilly where it was found.

Description

Length of body of living sexually mature specimen up to 2.1 mm, when squashed under a cover glass ( Figure 3 ). Outline, colour, arrangement of rhabdites and rhammites, and posterior adhesive papillae of the body correspond to the descriptions of the phena of Bradynectes sterreri given by Rieger (1971) and Faubel (1974b). Eyes, tactile cilia and adhesive glands along the lateral sides and head are absent. Pharynx, pharyngeal glands and gut disposed as in the phena described by Rieger (1971), Faubel (1974b) and Martens and Schockaert (1981).

Reproductiυe system. The single testis extends from the posterior part of the first body-half caudad and turns via a short vas deferens (80 M m long) into the seminal vesicle. Distally and proximally to the seminal vesicle, strong sphincters are present. The intervesicular duct enters the prostatic vesicle from behind. The distal part of the prostatic vesicle is encased in the proximal part of the stylet. The dimensions of the stylet of M. scilliensis ( Figure 3B ) are as follows (m. HT): convex side543 M m, concave side550.5 M m, length of distal oval opening531.5 M m, diameter of proximal opening 31 M m, longitudinal axis ( Figure 3C : dashed line a)556 M m. The longitudinal axis of the Sylt form is 43 M m.

Discussion

Rieger (1971) discerned three different subspecies of Bradynectes sterreri according to the place of collection: Kristineberg form, Carolina form and Robin Hood’s Bay form. Faubel (1974b) added a fourth form, the Sylt form. From the Scheldt estuary Martens and Schockaert (1981) discerned a fifth form, the Scheldt form. Both latter forms differ distinctly from the forms discerned by Rieger (1971) based on stylet shape and location of ovary between testis and intestine. Because of the constant location of the ovary between testis and gut, the forms of Faubel (1974b) and Martens and Schockaert (1981) represent true species: Bradynectes syltensis Faubel, 1974 and Bradynectes scheldtensis Martens and Schockert, 1981 . Bradynectes scheldtensis differs essentially from B. syltensis through the absence of a sphincter around the vas deferens and the shape and dimensions of the stylet. Bradynectes scilliensis found in a rockpool at White Island is identical with B. syltensis with regard to the presence of sphincters around the vas deferens. In B. syltensis , the seminal vesicle has only a proximal spincter but the seminal vesicle of B. scilliensis is provided with a proximal and distal spincter. The male stylet ( Figure 3C ) resembles that of B. syltensis , but with essential differences in shape and dimensions. Measurements of the length of the axis of the other forms were not given by the authors.

Family DOLICHOMACROSTOMIDAE Rieger, 1971

Figures

Figure 3. Bradynectes scilliensis sp. nov. (A) Dorsal view in squash preparation; (B) male copulatory apparatus; (C) male sclerotized stylet. Scale bars: 500 Mm (A); 50 Mm (B); 20 Mm (C).