Tripylocelis typica Haswell, 1907

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 : 47

Tripylocelis typica Haswell, 1907

( Fig. 19 )

Tripylocelis typica Haswell, 1907: 466–469 , pl. 35; Prudhoe, 1982: 370, 371, fig. 5.

Material examined: Several specimens, two sagittally sectioned. AM W.50268 (3 slides), W.51333 (3 slides, wet material). Specimens were collected from Australia, New South Wales: Minnie Waters 29°46’34.8”S, 153°18’08.6”E. Coll. Jorge Rodriguez and Justin McNab, December 6 th, 2019; Port Macquarie 31°27’27.7”S 152°56’04.4”E. Coll. Jane Williamson and Louise Tosetto, January 8 th, 2020; Norah Head rock platform , 33°16’43.14”S, 151°34’12.85”E, Toowoon Bay , 33°21’47.01”S, 151°30’7.31”E. Coll. Jorge Rodriguez, Mandy Reid and Alison Miller, March 15 th & 16 th, 2018 and Shelly Beach, Eden , 37°04’22.0”S, 149°54’45.6”E. Coll. Jorge Rodriguez, Jane Williamson, Patrick Burke, Louise Tosetto and Ryan Nevatte, July 10 th, 2018. Additional material from Australia, New South Wales, Port Jackson from the collections of the Australian Museum : AM G.6057.

Remarks: The studied specimens agreed with the original description by Haswell (1907). Externally, Tripylocelis typica presents a light brown dorsal colouration with darker brown pigments along the intestinal branches and pharynx, and a pair of nuchal tentacles on the anterior region ( Fig. 19A–D ). The male copulatory system is characterised by the presence of a seminal vesicle and lack of a prostatic vesicle, where the glandular epithelium lies instead around the distal end of the ejaculatory duct before joining the penis papilla. The penis is housed in a very elongated and ciliated male atrium ( Fig. 19E, F ). Haswell (1907) described the female system of T. typica with a ductus vaginalis that opens to the exterior through an accessory female pore next to the female gonopore. Prudhoe in 1982 found a specimen of this species where the ductus vaginalis loops back to the female atrium opening through a common female pore but did not consider this trait to be of specific relevance. The studied specimens of T. typica presented the morphology of the original description by Haswell (1907), were the ductus vaginalis opens next to the female atrium through an accessory female pore ( Fig. 19E, F ). However, the contraction of this region due to fixation may have warped the area around the gonopores in the specimen studied by Prudhoe (1982), making it appear as a single gonopore instead of two different ones.

Molecular remarks: Tripylocelis typica appeared nested within the Pseudostylochidae family with high support (98/1.00) together with the genera Pseudostylochus Yeri & Kaburaki, 1918 and Stylochoplanoides Bock, 1924 (as proposed by Oya & Kajihara, 2020). This differed from its original assignment to the Ilyplanidae family, represented in the Discoceloidea superfamily by the Phaenocelis and Amemiyaia clade. Therefore, this species has been transferred to the Pseudostylochidae family and the diagnosis emended.

Distribution: Australia: Port Jackson, New South Wales ( Haswell 1907, type locality); Wittelbee Point, South Australia ( Prudhoe 1982).

Suborder Cotylea Lang, 1884

Figures

FIGURE 19. Tripylocelis typica Haswell, 1907. A. Dorsal view of live specimen. B–C. Arrangement of the eyes. D. Details of the pharynx and reproductive systems. E. Sagittal reconstruction of the reproductive system. F. Histological sections of the reproductive system.