Prosthiostomum parvicelis Hyman, 1939

Ramos-Sánchez, Mariela, 2024, The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species, European Journal of Taxonomy 962 (1), pp. 1-67 : 44

Prosthiostomum parvicelis Hyman, 1939

Prosthiostomum parvicelis Hyman, 1939b: 6–8 , 13, figs 13–15 (type locality: Sullivan Bay, Santiago Island, Galapagos Archipelago, Ecuador).

Prosthiostomum parvicelis – Hyman 1953b: 193–194, 208, figs 12–14 (description).

Distribution

Sullivan Bay, Santiago Island; Cartago Bay, Isabela Island, Galapagos Island, Ecuador.

Habitat

Benthic (at a depth of 14.63 and 18.23 m on a sandy bedrock bottom).

Remarks

Hyman (1953b) recorded Prosthiostomum parvicelis as one of the most common polyclad species in the Galapagos Archipelago.The species has an elongated body with sparse marginal eyes distributed in the anterior region of the body, cerebral eyes and tubular pharynx positioned posterior to the cerebral eyes. The male reproductive system features a male gonopore anterior to the seminal vesicle, which as a prominent oval morphology, paired accessory vesicles positioned anterior to the seminal vesicle, spermiducal ducts oriented towards the posterior region of the body, and a penis papilla armed with a stylet. Hyman (1939a, 1953b) made a partial description of the female reproductive system in which she only schematized the position of the female gonopore and the distribution of the cement glands. It is recommended to review the type material of the species to provided a detailed redescription of the female reproductive system, together with the collection of new specimens to determine the coloration of these specimens.