Dugesia milloti de Beauchamp, 1952

Dugesia milloti de Beauchamp, 1952 View in CoL

Material examined

ZMA V.Pl. 787.1, stream of Roussette , Montagne d’Ambre, Madagascar (12°37 ʹ 0.00 ʹʹ S 49°8 ʹ 60.00 ʹʹ E), 17 September 1957, sagittal sections on nine slides GoogleMaps .

Mf N F 217-c, Andrangolaoka , Madagascar (19°1 ʹ 60.00 ʹʹ S 47°55 ʹ 0.00 ʹʹ E), coll. F. Sikora (specimens registered at the Berlin Museum on 25 March 1892), sagittal sections on nine slides; Mf N F 217-a, ibid., sagittal sections on eight slides; Mf N F 217-b, ibid., sagittal sections on five slides GoogleMaps .

Geographical distribution

Known from the following localities: (i) the type locality Morafenobé, forêt de Mahajeby, stream of Roussette, northwest Madagascar; (ii) Parc National de La Montagne d’Ambre, Diana Region, northern Madagascar; (iii) Andrangolaoka, Central High Plateau , east to Mantasoa Lake ; (iv) Cascade de Mutsamudu, Anjouan, Comoro Islands ( Fig. 1 View Figure 1 ).

Comparative discussion

As de Vries (1988) based her redescription of D. milloti primarily on specimens from Montagne d’Ambre (in our material represented by specimen ZMA V.Pl. 787.1) her account still is basically correct, although she did not provide specific information on the testes and the position of the mouth opening. Examination of our material learned that the small testes are situated dorsally and that the follicles extend from a short distance behind the ovaries to the posterior end of the body. The ovaries are located at a short distance (~400 μm) behind the brain, i.e. at about one-ninth of the distance between the brain and the root of the pharynx. The mouth opening is located at about one-sixth of the distance between the hind wall of the pharyngeal pocket and the root of the pharynx.

Characteristic for D. milloti are the two annular atrial folds or valves, the posterior valve receiving a bundle of longitudinal muscles that extends posteriorly from the penis bulb (cf. de Vries 1988: figs 9, 10; Fig. 3 View Figure 3 ). These annular atrial folds are much less clear in the old specimens from Andrangolaoka, which suffer from preservation and contraction artefacts ( Figs 4 View Figure 4 , 5 View Figure 5 ). However, in specimen MfN F217-a, folds in the atrium are still visible, presumably representing the most posterior valve—also receiving the longitudinal muscles from the penis bulb—as the anterior fold sits at the root of the penis papilla ( Fig. 6 View Figure 6 ).

As compared with the other long-eared species of Dugesia (see below), the copulatory apparatus of D. milloti is characterized by a slim, conical penis papilla and a large, valve-like diaphragm, the latter receiving the erythrophil secretion of penial glands that contributes to the formation of the spermatophore ( de Vries 1988: figs 9, 10; Figs 5 View Figure 5 , 6 View Figure 6 ).