Acoela (Acoelomorpha) from the northern beaches of the state of São Paulo, Brazil, and a systematic revision of the family Otocelididae Author Hooge, Matthew D. Author Rocha, Carlos E. F. text Zootaxa 2006 1335 1 50 journal article 10.5281/zenodo.174287 26ac73b9-1c53-4f82-bc02-78a055ba31e9 1175-5326 174287 Otocelis erinae sp. nov. ( Figs. 25–26 ) Type material . Holotype . MZUSP PL . 193, one set of 2-µm-thick serial sagittal sections of epoxy-embedded specimen stained with toluidine blue. Paratypes . MZUSP PL . 194, one set of 2-µm-thick serial frontal sections of epoxy-embedded specimens stained with toluidine blue, and MZUSP PL . 195, epoxy-embedded whole mount. FIGURE 24. Haplocelis dichona ; photomicrographs of living specimen. A. Dorsal view of squeezed specimen. B. Copulatory organs. Type locality . As Ilhas, São Sebastião, São Paulo, Brazil , from subtidal fine-grained sand ( 23°47’16.0”S , 45°42’31.2”W ). Other material examined . Living specimens in squeeze preparations from Pedro do Sino beach ( 23°44’49.8”S , 45°20’52.9”W ) and Praia de Feiticeira ( 23°50’45.2”S , 45°24’33.8”W ), Ilhabela, from intertidal and subtidal medium-grained sand; whole mounts for fluorescence imaging of musculature; photographs of living specimens in squeeze preparations. Etymology . Species name in honor of Ms. Erin Suhr of Portland, Oregon, USA . Description . Examined specimens 400 to 490 µm long and 120 to 130 µm wide ( Figs. 25 A, B). Anterior and posterior ends rounded. Body cylindrical. Epidermis completely ciliated. Rhabdoid glands in distinct rows ( Fig. 25 A). Body colorless in transmitted light, but digestive syncytium with green coloration. Frontal organ present, and seen especially well in living specimens in regions flanking statocyst ( Fig. 25 B). Mouth opening on ventral surface, middle of body. Digestive central syncytium extends from frontal glands posteriorly to male copulatory organ. FIGURE 25. Otocelis erinae sp. nov. ; photomicrographs of living specimens. A. Dorsal view of unsqueezed specimen. B. Dorsal view of squeezed specimen. C. Lateral view of posterior end. FIGURE 26. Otocelis erinae sp. nov. ; whole-mounts stained with Alexa-488-labeled phalloidin and viewed with confocal microscopy. A. Projection of whole specimen from ventral side. B. Dorsal projection through copulatory organs. C. Projection of everted male copulatory organ. Body-wall musculature with circular muscles that encircle the body along entire length of animal; straight longitudinal muscles present between frontal organ and anterior edge of mouth; longitudinal muscles with a longitudinal orientation anteriorly that bend medially to cross diagonally over the body (longitudinal-cross-over fibers) present in dorsal and ventral body walls; longitudinal muscles in the anterior half of body that wrap around the posterior rim of the mouth (U-shaped muscles) present in ventral body wall ( Fig. 26 A). Ovary unpaired, ventral; extends from level of mouth posteriorly to bursal nozzle ( Figs. 25 A, C). Testes paired, lateral to eggs. Testes extend from frontal gland posteriorly to level of the bursal nozzle ( Fig. 25 B). Male gonopore opens ventrally, anterior to female gonopore ( Figs. 25 C, 26). Gonopore opens directly to well-developed, muscular and glandular penis. Penis musculature composed of outer non-anastomosing longitudinal muscles and inner circular muscles ( Figs. 26 B, C). Lumen of penis filled with glandular secretions ( Fig. 25 C). Penis invaginated into muscular seminal vesicle filled with sperm and small granules that abut the posterior side of penis. Female gonopore opens ventrally, posterior to male gonopore and seminal vesicle ( Figs. 25 C, 26). Gonopore opens to a short ciliated antrum that leads to vagina ( Fig. 25 C). Immediately distal to antrum, vagina surrounded by muscular sphincter ( Fig. 26 B). Vagina passes dorsally to seminal vesicle; leads to seminal bursa with well-developed sclerotized bursal nozzle ( Figs. 25 A, B, 26B). Remarks . Within the genus Otocelis , O. erinae differs from all other described species in having an unpaired ovary. O. erinae is most similar to O. phycophilus Ehlers and Dörjes, 1979 and O. westbladi Ax, 1959 , which also have vaginal sphincters and separate male and female gonopores. In contrast to these two species, O. erinae has a slightly curved penis, not a hooked penis, and is without ocelli.