Stylochus erytheius Pérez-García, Gouveia, Calado, Noreña & Cervera, 2024, sp. nov.

Stylochus erytheius sp. nov. Fig. 4 Holotype. • MNCN 4.01/3059 to 3113 and 4336 to 4535, Station 11, 9 October 2014, 71 mm long, sagittal sectioned into 254 slides. Additional material. • MNCN 4.01/3962, Station 11, 20 April 2015, 35 mm long; • MNCN 4.01/3964, Station 11, 20 April 2015, 37 mm long; • MNCN 4.01/3966, Station 11, 2 February 2018, 120 mm long. Diagnosis. Body shape is oval with rounded anterior and posterior ends. Orange-brown dorsal background; numerous dark brown and whitish dots scattered on the dorsal surface; visible line of white dots along the main body axis; ventral surface pale orange; gonopores well-separated; with spermiducal bulbs; opening of the sperm duct distally located; penis papilla short. Description. Oval-shaped Stylochidae, with rounded anterior and posterior ends, fleshy, 71 mm in length (65.75 ± 39.76 mm) and 63 mm in width. Margins mostly smooth. Background colouration orange-brown, with multiple dark brown and white dots on the dorsal surface (as shown in Fig. 4 A). Additionally, a conspicuous line of white dots extends along the central axis of the body. Ventrally pale orange (Fig. 4 B). Nuchal conical tentacles transparent, with tentacular eyes at the base and tips (Fig. 4 C). Poorly visible cerebral eyes in two scattered clusters between the tentacles. Marginal eyes along the entire body margin. Pharynx ruffled centrally. Oral pore at the centre of the pharynx. Reddish, conspicuous gonopores well-separated (0.6 mm) posteriorly located. Reproductive system. Male copulatory apparatus comprises spermiducal bulbs, a tripartite seminal vesicle, and a free prostatic vesicle (Fig. 4 F). Spermiducal bulbs broad, run ventrally, and then posteriorly, turning dorsally before entering the seminal vesicle. Tripartite seminal vesicle anchor-like shape (Fig. 4 D, F), well developed. Prostatic vesicle, large and oval-shaped (1.5 mm long), belongs to the polyglandular (“ djiboutiensis ”) type (Faubel 1983). Muscular wall crossed by numerous extravesicular glands. The prostatic duct and the seminal duct join to form the short ejaculatory duct just before entering the penis papilla. Penis papilla elongated (0.21 mm), opening into a sinuous male atrium (Fig. 4 E). The female copulatory apparatus simple and inconspicuous, formed by the vagina externa and interna. Without Lang’s vesicle. The oviducts open together into the posterior region of the vagina interna. Abundant shell and cement glands open into the vagina externa and distal region of the vagina interna. Type locality. La Caleta Beach, Cadiz, Spain. Etymology. Named after Erytheia, a small island where the Phoenicians settled approximately 1100 BC. This area is where the beach of La Caleta is located, the type locality of the new species. Remarks. A discussion of this species is included together with S. marimarensis sp. nov. Biology. Specimens were collected from rocky substrates under stones in the intertidal zone. Distribution. This species has only been found in La Caleta, Cadiz, Spain.