Prostheceraeus crisostomum Cuadrado & Rodríguez & Moro & Grande & Noreña 2021, sp. nov.
Creators: name: Cuadrado, Daniel
name: Rodríguez, Jorge
name: Moro, Leopoldo
name: Grande, Cristina
name: Noreña, Carolina
Publisher: name: Zenodo
Year: 2021
Subjects: Biodiversity
Taxonomy
Animalia
Platyhelminthes
Rhabditophora
Polycladida
Euryleptidae
Prostheceraeus
Prostheceraeus crisostomum

description: Prostheceraeus crisostomum sp. nov.
urn:lsid:zoobank.org:act: EC7A7E2B-99FD-447D-A189-676144875AC2
Figs 1C, 3 A–D
Etymology
The name of the new species, Prostheceraeus crisostomum, is dedicated to the little cat, Crisostomo, roommate during the description of this species.
Material examined
Holotype
CAPE VERDE • Sal Island, Calheta Funda; 16°39′03.34″ N, 22°56′42,94″ W (Fig. 1C V 3); 8 Jul. 2018; Leopoldo Moro leg.; MNCN 4.01/2684 to 2698 (15 slides). One sagittally sectioned specimen stained with AZAN.
Description
BODY. Shape elongated. Length 0.5 cm. Smooth dorsal surface; background pigmentation ivory white, darker along the middle dorsal region of the body between the cerebral eyes and the posterior end of the body. In the posterior middle end it shows a large conspicuous black spot. Small black dots on the entire dorsal surface (Fig. 3E). Two marginal tentacles, separate. Tentacular eyes scarce and widely dispersed between the tentacles. Cerebral eyes arrow-shaped located by the central midline (Fig. 3F). Bell-shaped pharynx located in the first body half. Ventral sucker in the middle of the body. Male and female genital pores well separated and located after the pharynx (Fig. 3 G–H).
MALE REPRODUCTIVE SYSTEM. Male copulatory organ oriented forward. The muscular prominent penis papilla houses a conical, elongated stylet of pseudosclerotized nature. The rounded and well developed prostatic vesicle joins transversally with the sperm duct and lies over the penis papilla (Fig. 3H). Muscular seminal vesicle oval, dorsally located and caudo-frontally oriented. The vasa deferentia join at the ventro-caudal region of the vesicle and the sperm duct open ventro-frontally. Seminal and prostatic vesicles open together into the proximal region of the developed penis papillae. The male atrium surrounded the penis papillae and opens near the posterior end of the pharynx.
FEMALE REPRODUCTIVE SYSTEM. Atrium elongated and highly ciliated, continues dorsally into the long but not ciliated vagina externa. The vagina externa narrows into a non-ciliated small cavity that continues in the vagina interna. It presents a widened epithelium and ends with the entry of the oviducts (Fig. 3H). Cement and shell glands lie around the female atrium, vagina externa and distal region of the vagina interna, but opens into the small cavity (pouch) between both vaginas.
Remarks
Prostheceraeus crisostomum sp. nov. belongs to the genus Prostheceraeus due to the presence of cerebral, frontal and marginal eyes, true anterior tentacles, bell-shaped pharynx, the male copulatory system with prostatic vesicle, penis armed whit stylet and the presence of multiple uterine vesicles.
The genus Prostheceraeus comprises 10 species, mainly characterized by coloration pattern, with colorful pigmentations and dorsal longitudinal lines of different widths, as in P. fuscolineatus Dixit, Raghunathan & Chandra, 2017, P. roseus, P. pseudolimax Lang, 1884, P. giesbrechtii, P. vittatus (Montagu, 1815) and P. zebra (Hyman, 1955) or with fine, transversal lines as in P. crozieri (Hyman, 1939).
Three other species of Prostheceraeus show a color pattern free of lines or bands: P. albocinctus Lang, 1883, P. moseleyi and P. rubropunctatus Lang, 1884. These three species, together with P. crisostomum sp. nov., have a dotted pattern, but the background colors are different in the four species: caramel brown background with white or whitish spots and white marginal line in P. albocinctus, blue-gray or cream background with black dots and yellow marginal band in P. moseleyi and finally P. rubropunctatus with a pink to reddish background color, white dots and without marginal band. The base coloration of P. crisostomum is similar to P. albocinctus, but much clearer and almost ivory; the dorsal points are black like in P. moseleyi and lacks a marginal line or band similar to P. rubropunctatus. All these differences delimit P. crisostomum sp. nov. as a new species of the genus Prostheceraeus.
description: Published as part of Cuadrado, Daniel, Rodríguez, Jorge, Moro, Leopoldo, Grande, Cristina & Noreña, Carolina, 2021, Polycladida (Platyhelminthes, Rhabditophora) from Cape Verde and related regions of Macaronesia, pp. 1-43 in European Journal of Taxonomy 736 on pages 16-18, DOI: 10.5852/ejt.2021.736.1249, http://zenodo.org/record/4561525