Prostheceraeus crisostomum, Cuadrado & Rodríguez & Moro & Grande & Noreña, 2021

Cuadrado, Daniel, Rodríguez, Jorge, Moro, Leopoldo, Grande, Cristina & Noreña, Carolina, 2021, Polycladida (Platyhelminthes, Rhabditophora) from Cape Verde and related regions of Macaronesia, European Journal of Taxonomy 736, pp. 1-43 : 16-18

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 .

Figures

Fig. 1. Location of sampling points, distribution of the Macaronesian archipelagos and limitation of regions: Lauri-Macaronesia or Lusitanian Macaronesia (white); Central Macaronesia or Eumacaronesia (bordeaux) and Great Macaronesia (green). Abbreviations:A1 = San Miguel Island, Azores; C1 = Pasito Blanco, Gran Canaria, Canary Islands; C2 = Tenerife, Canary Islands; C3 = Garachico, Tenerife, Canary Islands; C4 = Amarilla Golf, Tenerife, Canary Islands; CV1 = Astillero Mindelo, S„o Vicente Island, Cape Verde; CV2 = Bahía das Gatas, S„o Vicente Island, Cape Verde; CV3 = Calheta Funda, Sal Island, Cape Verde; M1 = Ifni, South Morocco; M2 = Agadir, South Morocco.

Fig. 3. A–D. Prostheceraeus crisostomum sp. nov. (MNCN 4.01/2684 to 2698). A. Whole live animal, dorsal view. B. Anterior region with cerebral eyes cluster and tentacles (black arrows). C. Histological section of the reproductive system stained with AZAN. D. Histological section of the whole animal stained with AZAN and sagittal reconstruction. – E–I. Pseudoceros rawlinsonae var. galaxy (MNCN 4.01/2729 to 2798). E. Whole live animal, dorsal view. F. Anterior region with eyes cluster and tentacles (white arrows). G. Whole live animal, ventral view. H. Histological sagittal section of male and female copulatory organ. I. Sagittal reconstruction of the reproductive system. Abbreviations: see Material and methods.