Koinostylochus burchami ( Heath & McGregor, 1912 )

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 : 9-10

Koinostylochus burchami ( Heath & McGregor, 1912)

Planocera burchami Heath & McGregor, 1912: 461–462 , pl. 13 fig. 9, pl. 15 fig. 27, pl. 18 fig. 44 (description).

Discosolenia washingtonensis Freeman, 1933: 133–136 , pl. 20 figs 27–28, pl. 21 fig. 29, pl. 23 fig. 40 (type locality: Monterey Bay, California, United States).

Pseudostylochus burchami – Hyman 1953a: 356, 358–359, figs 125–126. — Brusca 1980: 70–72 (identification keys); 2005: 69 (checklist, new record from Rocas Consag, Baja California Sur, Mexico).

Koinostylochus burchami – Faubel 1983: 60 (new combination).

Distribution

The species is found from Puget Sound to the Revillagigedo Islands in the Mexican Pacific, including locations such as San Juan Island in Puget Sound, Depoe Bay in Oregon, and various sites along the California coast such as San Francisco Bay, Monterey Bay, and Anacapa Island. It is also recorded in Baja California, specifically Roca Consag in Baja California Sur, Mexico, and Clarion Island near Manzanillo, Colima, Mexico.

Habitat

Benthic. The species inhabits depths ranging from 18 m to 70 m ( Heath & McGregor 1912; Freeman 1933; Hyman 1953a).

Remarks

The species was initially described as Planocera burchami by Heath & McGregor (1912) in Monterey Bay, California, and later as Discosolenia washingtoniensis by Freeman (1933) in Puget Sound. Hyman (1953a) reviewed specimens from these localities and from the Gulf of California, along with the original descriptions by Heath & McGregor (1912) and Freeman (1933), and concluded that they were the same species, thus establishing all specimens as Pseudostylochus burchami . Faubel (1983) subsequently transferred the species to the genus Koinostylochus based on the presence of a prostatic vesicle with a smooth glandular lining dorsal to the male atrium and an inert penis papilla.

Freeman (1933) described Koinostylochus burchami as having a male reproductive apparatus with a short, sharp penis papilla armed with small spines; however Hyman (1953a), after reviewing specimens from the same locality and the description of the species by Freeman (1933), stated that this character is absent and considered it an error, Hyman (1953a) also noted that the presence of the two deep pits observed by Heath & McGregor (1912: pl. 18 fig. 44) is at the superficial level because in the sagittal sections of the reproductive system, they are not observed. Therefore, a thorough revision of the biological material of the species is suggested.