Marcusia ernesti Hyman, 1953

Soutullo, Patricia, Cuadrado, Daniel & Noreña, Carolina, 2021, First study of the Polycladida (Rhabditophora, Platyhelminthes) from the Pacific Coast of Costa Rica, Zootaxa 4964 (2), pp. 363-381 : 373

Marcusia ernesti Hyman, 1953

( Fig. 6 )

Material examined: One specimen. Sagittal histological sections stained with AZAN of one individual. 42 slides: MNCN 4.01/2461 to MNCN 4.01/2502.

Location: Playa Carbón Beach , in Las Baulas National Marine Park of Guanacaste, Costa Rica, 10 ° 20’53.4 “N 85 ° 51’44.5” W; May 87 2018. Fig. 6A .

Habitat: Low intertidal, below stones on sand

Description: External features ( Fig. 6B,C ): Oval-elongated body shape, wavy margins, anterior and posterior end rounded. Small marginal tentacles in the frontal region, separated. Length: 23 mm. Dark brown almost black dorsal colouration with white irregular spots. Whitish ventrally. Colourless region at cerebral eye level. Pharynx ruffled large located in the central area.

Reproductive system: Consists of a common elongated atrium in which the male atrium opens laterally and the female distally ( Fig. 6D ). The male copulatory organ is formed by an elongated muscular bulb that encloses the seminal vesicle and the penis papilla. The ejaculatory duct is lined by a well-developed prostatic glandular epithelium ( Fig. 6C ). Without prostatic vesicle.

The female apparatus includes the vagina that turns caudally and widens, covered with glandular epithelium.

Distribution: Marcusia ernesti has been found only in the Pacific Ocean. This species is known from Baja California, Gulf of California, Sonora ( Mexico), Clarion Island ( Mexico) (Hyman, 1953) and now from Costa Rica in this study.

Figures

FIGURE 6. Marcusia ernesti Hyman, 1953. A. Distribution map and sample points; B. Whole live animal, dorsal view; C. Ventral view of whole live animal; D. Histological sections of the copulatory organs stained with Azan. E. Sagittal reconstruction of the reproduction system (D, E anterior end to the left).