Diposthus popeae Hyman, 1959

Rodríguez, Jorge, Hutchings, Pat A. & Williamson, Jane E., 2021, Biodiversity of intertidal marine flatworms (Polycladida, Platyhelminthes) in southeastern Australia, Zootaxa 5024 (1), pp. 1-63 : 50

Diposthus popeae Hyman, 1959

( Fig. 20 )

Diposthus popeae Hyman, 1959: 15 , figs 19–21.

Material examined: One specimen sagittally sectioned. AM W.53209 (5 slides). A specimen was collected at low tide under rocks from Australia, New South Wales, Bottle & Glass, 33°50’53.9”S, 151°16’12.3”E. Coll. Jorge Rodriguez and Justin McNab, October 25 th, 2019. Additional material from Australia, New South Wales, Long Reef from the collections of the Australian Museum : AM W.3699 (holotype), W. 3700 .

Remarks: Hyman (1959) remarks the poor condition of the preserved specimen in the original description and the difficulties of reconstructing the male copulatory system. Based on the studied specimen from Bottle & Glass, Diposthus popeae Hyman, 1959 possesses a slender body shape with white dorsal colouration and a pair of pseudotentacles in the anterior margin ( Fig. 20A, B, D ). Internally, the gonopores lie very close together, the male copulatory system is directed perpendicularly and consists of a thick and enlarged seminal vesicle and a long and slender penis papilla ( Fig. 20C, E, F ). The type and only other species of the genus, D. corallicola Woodworth, 1898 , from the Great Barrier Reef appears to have prostate tissue in a fold adjacent to the penis papilla and separate from the rest of the male copulatory system. In the studied specimen of D. popeae such organ cannot be found; instead, it appears the glandular function is carried out by the penis itself, having glandular tissue ( Fig. 20F ) similar to the case of the ejaculatory duct of Tripylocelis typica Haswell, 1907 . The female system consists of a vertically running vagina externa that turns posteriorly after connecting with the vagina interna and is provided with a circular Lang’s vesicle. A pair of cement pouches are also present ( Fig. 20F ).

Distribution: Australia, New South Wales, Long Reef ( Hyman 1959).

Figures

FIGURE 20. Diposthus popeae Hyman, 1959. A. Dorsal view of live specimen. B. Dorsal view of a fixed specimen, treated with a clearing agent. C. Details of the reproductive systems. D. Arrangement of the eyes. E. Sagittal reconstruction of the reproductive system. F. Histological sections of the reproductive system.