Callioplana marianae Ramos-Sánchez, 2024, sp. nov.
Creators: name: Ramos-Sánchez, Mariela
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Animalia
Platyhelminthes
Polycladida
Callioplanidae
Callioplana
Callioplana marianae

description: Callioplana marianae sp. nov.
urn:lsid:zoobank.org:act: 3A061F94-72BB-4EBA-BB1B-F022A4F96D4C
Figs 1–3
Diagnosis
Callioplana marianae sp. nov. is characterized by a beige background coloration with light brown and white pigmentation that gives it a reticulated appearance, nipple-shaped nuchal tentacles, cerebral and tentacular eyes, absence of marginal eyes, a folded pharynx located slightly posterior to the first third of the body, separated gonopores, an oval seminal vesicle located posterior to the free prostatic vesicle that presents a striated internal glandular lining, a penis papilla armed with a filiform stylet, and a tripartite Lang’s vesicle located posterior to the male gonopore.
Etymology
This species is named after the author’s beloved mother Mariana Sánchez.
Type material
Holotype
MEXICO • 1 ⚥ (as sagittal sections); southern Mexican Pacific, Oaxaca, Zipolite, Camarón Beach; 15°39′43″ N, 96°31′33.6″ W; depth 0.5 m; 25 Mar. 2017; MRS, MB, AMRM, NMP leg.; in rocky intertidal; reproductive structures in two slides; UMAR PLAT–046.
Paratypes
MEXICO • 8 ⚥⚥, 6 (as whole assemblies), 1 (as front section); same data as for holotype; UMAR PLAT–047A–D, UMAR PLAT–048.
Type locality
Camarón Beach, Zipolite, Oaxaca, Mexico.
Description of external features
Holotype (⚥ UMAR PLAT – 046)
COLOR. The background color is beige with brown to olive green; the periphery is slightly translucent with light brown and white pigmentation; the reticulate coloration pattern radiates from the central region of the pharynx to the periphery of the body (Fig. 1A), the ventral region is white. Specimens stained with Mayer’s carmalum are pink (Fig. 1C–D).
BODY. Elliptical (Figs 1A–D, 3A), 15–20 mm long (n = 5, μ = 18, SD = 2) and 10–12 mm wide (n = 5, μ = 11, SD = 1).
TENTACLES. Rudimentary nipple-shaped nuchal tentacles (Figs 1F, 3B) are located in the anterior margin of the body, the distance between tentacles being 0.6 –0.9 mm (n = 3, μ = 0.7, SD = 0.16).
EYES. Marginal eyes absent; with 17–25 (n = 3, μ = 20, SD = 3) tentacular eyes, diagonally distributed, anterior and posterior to the base of the nuchal tentacles (Figs 1F, H, 3A–B); with 17–36 (n = 3, μ = 22, SD = 7) cerebral eyes distributed in an elongate fashion beginning sparsely at the posterior margin of the brain and widening forward (Figs 1H, 3B).
BRAIN. Bilobed, 0.2–0.6 mm (n = 3, μ = 0.4, SD = 0.28) long and 0.2–0.7 mm (n = 3, μ = 0.5, SD = 0.31) wide; globuli cell masses oval-shaped, located in the anterior region of the brain (Figs 1E, 3B).
DIGESTIVE SYSTEM. The pharynx is relatively small and sparsely folded; located slightly posterior to the first third of the body at 5 mm (n = 3, μ = 0.5, SD = 0.31) from the anterior margin of the body (Figs 1G, 3A), 1–1.3 mm (n = 3, μ = 1.2, SD = 0.19) from the male gonopore; the mouth is located in the central region of the pharynx.
GONOPORES. Separated, located in the last third of the body (Fig. 3D). Male gonopore at 6–6.3 mm (n = 3, μ = 6.2, SD = 0.21) from the anterior margin and 1–1.3 mm (n = 3, μ = 1.2, SD = 0.19) from the pharynx. The female gonopore (Fig. 2F–G) is positioned posterior to the male gonopore at 0.5–0.8 mm (n = 3, μ = 0.6, SD = 0.02) of distance.
Description of internal features
MALE REPRODUCTIVE SYSTEM. The male gonopore is located in the last third of the body; the rest of the male reproductive system is oriented toward the anterior part of the male gonopore; it has spermiducal ducts that are oriented toward the anterior region of the body and extend to the last third of the pharynx and subsequently descend toward the posterior region of the body. A prominent oval-free prostatic vesicle (Figs 1I, 2D, 3C–D), with internal ridged glandular lining (Figs 2D, 3C), is located dorsal to the seminal vesicle (Figs 2A, D, 3C). Oval seminal vesicle (Figs 2D, 3C–D). Penis papilla is short (Figs 1I, 2F), 94 µm long, armed with a long filiform sclerosed stylet (Figs 2B, E, G, 3C–D), measuring 200–400 µm (n = 3, μ = 300, SD = 141.42) in length. The male atrium is widened (Figs 2G, 3C).
FEMALE REPRODUCTIVE SYSTEM. The oviduct, oriented toward the anterior region of the body, surrounds the pharynx (Fig. 3A) and connects directly to the proximal end region of the vagina; the vagina is sparsely developed (Figs 2C, 3D), oriented toward the posterior region of the body, cement glands are abundant. Lang’s vesicle tripartite is Y-shaped (Figs 1I, 2A, 3C); the proximal ends are oriented towards the anterior region of the body and reach the last third of the oviduct, while the distal end is oriented towards the posterior region of the female gonopore.
Taxonomic remarks
Within the TEP, Callioplana marianae sp. nov., Hylocelis californica (Heath & McGregor, 1912), and Interplana sandiegensis (Boone, 1929) share a tripartite Lang’s vesicle. However, Callioplana marianae has a free prostatic vesicle (Figs 2D, 3D), whereas H. californica and I. sandiegensis have an interpolated prostatic vesicle. Additionally, Callioplana marianae possesses nuchal tentacles (Figs 1H, 3B) and a penis papilla (Fig. 2F), features that relate it more closely to the family Callioplanidae than to others within the suborder Acotylea.
The family Callioplanidae has 14 valid genera, and the new species described here belongs to the genus Callioplana and is established as Callioplana marianae sp. nov., due to the presence of nuchal tentacles, cerebral and tentacular eyes and a highly developed Lang’s vesicle; this last character is absent in the genera Asolenia Hyman, 1959, Crasiplana Hyman, 1955, Discostylochus Bock, 1925, Kaburakia Bock, 1925, Meixneria Bock, 1913, Okakarus Holleman, 2007, Parastylochus Bock, 1913, Tokiphallus Faubel, 1983, and Trigonoporus Lang, 1884.
Callioplana marianae sp. nov. is further distinguished from the genus Koinostylochus Faubel, 1983, which has a simple and oval Lang’s vesicle, in contrast to the tripartite and highly developed Lang’s vesicle of the new species. Additionally, Callioplana marianae lacks marginal eyes, a feature that separates it from the genera Ancoratheca Prudhoe, 1982, Munseoma Bulnes, Faubel & Park, 2005 and Neostylochus Yeri & Kaburaki, 1920, all of which have marginal eyes.
The genus Callioplana was established by Stimpson (1857) and amended by Yeri & Kaburaki (1918). It is characterized by the presence of nuchal tentacles, cerebral and tentacular eyes, a rod-shaped penis papilla (or “a rod-shaped muscular extension of the ejaculatory duct, with an outward bulge” as was mentioned by Faubel 1983) and a highly developed Lang’s vesicle.
Previously, two species were described in Callioplana: C. marginata Stimpson, 1857 from Japan, and C. evelinae Marcus, 1954 from San Sebastian Island, Brazil. Both species differ from C. marianae sp. nov. in the color and pattern of dorsal coloration, the position of the prostatic vesicle (Table 1), and essentially in the morphology of a Lang’s vesicle (tripartite and Y-shaped in C. marianae vs bifurcated in C. marginata and C. evelinae) and a penis papilla (armed with a filiform stylet in C. marianae, vs unarmed in C. marginata and C. evelinae).
Distribution and habitat
Tropical Eastern Pacific. Central coast of Oaxaca: Camarón Beach, Zipolite, Oaxaca, Mexico. Intertidal, the polyclads were found under rocks in the breakwater zone.
description: Published as part of Ramos-Sánchez, Mariela, 2024, The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species, pp. 1-67 in European Journal of Taxonomy 962 (1) on pages 3-9, DOI: 10.5852/ejt.2024.962.2683, http://zenodo.org/record/13947260