Bisacculosuteri marcelae sp. nov.

(Figures 4 A–H, 5A–E, 6A–L)

http://zoobank.org/NomenclaturalActs/8a0713a4-6259-4528-8e76-2d09d7d2e79 8

Type locality. Agua Blanca Beach, Oaxaca, México (15°43’58”N, 96°48’40.21”W) .

Type material. Three specimens. Holotype: UMAR-PLAT 007, Agua Blanca Beach, Oaxaca, southern Mexican Pacific; in tide pools, on Padina sp., together with encrusting bryozoans ( Jellyella sp.), 0.5 m, Jan 1, 2014, coll. MRS; specimen in a whole mount. Paratype: UMAR-PLAT 037 A–D, from Agua Blanca, same as holotype; one specimen in histology sections (sagittal sections of reproductive structures in four slides; the remaining portion mounted on Canada balsam in one slide).

Other material examined. Oaxaca: One specimen from Agua Blanca, same as type material; used for photography preserved (Fig. 4A), but destroyed in the mount process .

Description of external features.

Color. Translucent in vivo; pharyngeal, intestinal and reproductive region with white granules on translucent background; alcohol-preserved specimens have white opaque to light-brown coloration (Fig. 4A). The specimen stained with Mayer’s carmalum has a purple to pink color (Fig. 4B).

Body. Oval to circular slightly narrow in the anterior region of the body (Figs 4 A–B, 5A). The specimens are 3.25–5.3 mm long and 2.2–3.8 mm wide.

Tentacles. Rudimentary pyriform nuchal tentacles (Figs 4E, 5A), located at 1.2–2.6 mm from the anterior margin of the body; distance between both tentacles is 0.8–1.6 mm.

Eyes. Marginal eyes absent; with between 25–50 tentacular eyes located around the tentacles; with 22–55 cerebral eyes at the periphery of the brain and 1.12 mm from the anterior margin of the body (Fig. 4C).

Brain. Bilobed, 0.2 mm long and 2.1 mm wide; located at 1.3 mm from the anterior margin of the body; globuli cell masses triangular shaped, located in the anterior region of the brain (Fig. 4D).

Digestive system. The pharynx is located immediately behind the tentacles (Figs 4E, H, 5A, 6K) located in the central region of the body (Figs 4E, 5A), highly branched, 2.4 mm long and 1.7 mm wide; mouth in center.

Gonopores. Male and female gonopores located in the last third of the body, posterior to the pharynx. Male gonopore (Figs 4F, H, 5B) located at 3.95 mm from the anterior margin of the body, 0.2 mm from the pharynx and 0.12 mm from female gonopore (Figs.4 G–H, 5B).

Description of internal features.

Male reproductive system. Seminal vesicle (Figs 4H, 5B, 6D, L) oval and prominent, 0.7 mm length and 0.32 mm width; covered by a very thin epithelium connected by an ejaculatory duct (Fig. 6D) to the interpolated prostatic vesicle (Fig. 6C), which is slightly oval and prominent, poorly differentiated, covered by a smooth glandular epithelium, and has 0.4 mm length and 0.22 mm width. A sclerotized stylet cylindrical with acicular tip (Figs 4F, 5B) 0.07 mm length and 0.02 mm width, connected directly to the penis papilla (Fig. 6E), which is 0.22 mm long and 0.23 mm wide, highly muscular and large. Spermiducal vesicles (Fig. 6F) oriented towards the posterior region of the body are visible in the sections only; testicles are distributed throughout the body (Fig. 6I).

Female reproductive system. Cement glands (Figs 5B, 6H, J) are located posteriorly to male reproductive system. Vagina strongly muscularized (Fig. 6J), with a paired uterine duct and a uterine sac (Figs 4H, 5B, 6 G–H, K), both oriented towards the anterior region of the body. Uterine sac strongly muscularized (Figs 6G, K), wide proximally (Figs 4 G–H, 5B) and ovoid distally. Uterine vesicles (Figs 4H, 5B, 6G, I) leave the distal region of the uterine sac towards the posterior region of the body. A pore of the vaginal duct is present posterior to female gonopore (Figs 4G, 5B). The Lang’s vesicle is 0.1 mm long and 0.15 mm wide; Lang’s vesicle duct poorly developed, with 0.25 mm length and 0.1 mm width (Fig. 6J); ovaries (Fig. 6I) and oviducts (Figs 6 K–L) distributed throughout the body.

Habitat. Intertidal, in tide pools. Three specimens of Bisacculosuteri marcelae sp. nov. were found as epibionts on the seaweed Padina sp. and the encrusting bryozoans Jellyella sp. we also found egg masses of B. marcelae sp. nov. deposited on the bryozoans. Other taxa found in the tide pool included seaweed of the genus Ulva, diatoms, polychaetes, brachyuran crabs, amphipods and isopods.

Distribution. This species is known only from Agua Blanca Beach, Oaxaca, southern Mexican Pacific (Fig. 12).

Etymology. This species is named after Diana Marcela Bolaños-Rodríguez, Colombian researcher, in recognition of her extensive taxonomic, systematic and morphological work on polyclads.

Taxonomic remarks. The remarks about this species and comparison with other genera of Leptoplanidae are included in the remarks of genus Bisacculosuteri .