Cratera hina ( Marcus, 1951 ) Lago-Barcia & Carbayo, 2018

Lago-Barcia, Domingo & Carbayo, Fernando, 2018, Taxonomic revision of four species of the Neotropical land planarian genera Cratera and Geoplana (Platyhelminthes, Tricladida) with a description of two new species and an emendation of Cratera, Zootaxa 4500 (4), pp. 517-542 : 522-525

Cratera hina ( Marcus, 1951) , comb. n.

Synonymy

Geoplana hina Marcus, 1951

Geoplana hina ; Carbayo et al., 2013, non Cratera hina ( Marcus, 1951)

Material examined. Reserva Biológica do Alto da Serra de Paranapiacaba, Santo André, State of São Paulo, (- 23.77, -46.30). Holotype ( MZUSP PL 2118 ). November 1950, transverse sections of pre-pharyngeal region on 2 slides (S431-S432); sagittal sections of pharynx on 2 slides (S433-S434); sagittal sections of copulatory apparatus on 3 slides (S428-S430). F5682 ( MZUSP PL 2119 ). F. Carbayo et al., coll. 21 December 2012, horizontal sections of anterior end on 9 slides; transverse sections of pre-pharyngeal region on 3 slides; horizontal sections of pharynx and copulatory apparatus on 10 slides.

Note: Specimen MZUSP PL 1008, examined in Carbayo et al. (2013), is not conspecific (see Remarks on C. picuia sp. n.).

Our observations of the material examined are in agreement with Marcus’ (1951) description. Here we complement the original description and make a reinterpretation of the ventral cavity of the female atrium.

Distribution. Only known from the type locality, Reserva Biológica do Alto da Serra de Paranapiacaba, Santo André, State of São Paulo, Brazil.

Diagnosis. Species of Cratera some 60 mm in maximum length. Dorsal coloration a median orange band and a lateral black band on each side. Dorsal and ventral epidermis ciliated. Dorsal eyes initiating in cephalic region. Penis bulb short, extending very little anteriorly to the penis papilla. Proximal portion of prostatic vesicle bifurcated, extrabulbar and attached from penis bulb. Ejaculatory duct not dilated distally. Muscle tube surrounding ejaculatory duct thick, with diameter equivalent to three times to that of the ejaculatory duct. Underlying muscularis of the penis papilla consisting of three layers, two circular and a longitudinal in between. Dorsal insertion of penis papilla slightly anterior to the ventral. Penis papilla projects into female atrium. Dorsal surface of the male atrium pierced by numerous glands. Common glandular duct absent.

Description. External aspect. Color of the dorsum consists of a median orange band and a lateral black band, on each side of the body; anterior margin black ( Fig. 3A ). Eyes monolobulated. They spread from anterior tip to rear end of the body, and occupying the dorsal surface to the maximum extent of about 1/4-1/3 of the body width in mid body, on either side. Clear halos present around the eyes. Sensory pits are 15 µm deep. They are arranged in a single row and contour the anterior extremity. They extend backwards to at least a length equal to 31% of body length. The creeping sole is as wide as 90% of the body width, provided with 5 µm long cilia at the pre-pharyngeal region. Relative mouth:body length and relative gonopore:body length, 68% and 80%, respectively in holotype, and 71% and 81% in specimen F5682. Dorsal epidermis provided with 2.5 µm long cilia.

Internal morphology. There is a glandular margin, which is composed of two types of cells secreting erythrophil and xanthophil granules, respectively. Cutaneous musculature with the usual three layers present in the subfamily Geoplaninae : a thin subepithelial circular layer (2.5 µm thick, dorsally and ventrally) followed by a diagonal with decussate bundles (10 µm thick dorsally, 22 µm ventrally), and then a longitudinal layer (45 µm thick dorsally, 55 µm ventrally) arranged in bundles. Cutaneous musculature as thick as 12% of body height.

The three most common parenchymal muscle layers are also present, a weak dorsal layer of decussate diagonal fibers (25 µm thick), a supraintestinal layer of transverse fibers (40 µm thick), and a subintestinal layer (40 µm thick). There are no subepidermic, nor parenchymal muscle modifications in the cephalic region.

Esophagus present, 17% of pharynx length. Relative position mouth:pharyngeal pouch length, of 60%. Pharynx cylindrical. Outer epithelium of the pharynx underlain by a thin layer (3 µm thick) of longitudinal muscle, followed by a thin layer of circular fibers (8 µm thick). Inner pharynx musculature consisting of a subepithelial layer (2 µm thick) of longitudinal musculature, followed by a circular layer (100 µm thick) and an outermost 10 µm thick layer of longitudinal fibers.

Testes are arranged in a single row on each side of the body. They extend from 400 µm behind the level of the ovaries (equal to 29% of the body length, specimen F5682) to closely the root of the pharynx (equal to 68% of the body length). Shortly anterior to the penis bulb, sperm ducts curve medially to communicate with the two short branches of the prostatic vesicle. The unpaired section of the prostatic vesicle, attached to the penis bulb, runs dorsally, subsequently penetrates the penis bulb to continue as an ejaculatory duct. Penis bulb moderately developed, extending very little anterior to the penis papilla. The prostatic vesicle is lined with a ciliated epithelium, and is pierced by glands producing erythrophil granules. It is surrounded by a circular muscle layer (10 µm thick). This duct traverses the central region of the penis papilla to open at its tip; there is no dilation in the distal portion of the duct. The ejaculatory duct is lined with a ciliated epithelium. This duct is 25 µm in diameter, and is surrounded by a conspicuous 30 µm thick circular muscle which becomes thinner distally ( Fig. 4B ). This muscle constitutes a tube with diameter equivalent to three times the diameter of the ejaculatory duct. The penis papilla is conical, horizontal, and is lined with a cuboidal, non-ciliated epithelium ( Fig. 4 B-D). Its underlying muscularis is compact; it consists of an 18 µm thick layer of circular fibers followed by a 5 µm thick of longitudinal fibers and an innermost 12 µm thick layer of circular fibers ( Fig. 4B ). The stroma of the penis papilla is traversed by numerous glands discharging erythrophil granules through the epithelium of the papilla; they pierce its dorsal epithelium at highest density. The muscularis of the male atrium consists of a 10 µm thick circular muscle, followed in the distal half of the atrium by some longitudinal fibers. There is a distinct dorsal surface of the male atrium pierced by numerous glands producing pinkish granules ( Fig. 4C, E ).

Ovaries 500 µm long and 200 µm wide (specimen F5682). They are located at a distance from anterior end equal to 31% of body length. The ovovitelline ducts arise from the dorso-lateral aspect of the ovaries. Shell glands pierce distal section of these ducts only ( Fig. 4E ). Thus, there is no common glandular ovovitelline duct. The female genital duct projetcs from postero-dorsal portion of female atrium, and is lined with a non ciliated epithelium. This epithelium is underlain by a 10 µm thick circular muscle layer. The female atrium is a cavity with 1-2 lateral folds; female:male atrial length, 1:1.5. This atrium is lined with a 25 µm high epithelium, which is underlain by a 20 µm thick muscle layer of circular and longitudinal fibers ( Fig. 4D ); circular muscle fibers are predominant in posterior section of female atrium.

Remarks. Prof. Eudóxia M. Froehlich kept in her office the histological slides of most land planarians studied by Marcus. Histological slides in her collection include more than one specimen labeled only “hina”. Marcus presented diagrammatic reconstructions of the pharynx and the copulatory apparatus of the holotype (Figs. 259-264 in Marcus, 1951). These reconstructions fully match the organs on the histological sections of what we consequently consider to be the holotype.

Marcus (1951) described the distal portion of the penis papilla as housed in a ventral pouch of the female atrium. Our interpretation of parasagittal sections of the two specimens is that the presumed pouch is actually part of the single space constituting the female atrium which is partially occluded by its own lateral fold. Marcus also distinguished a short female genital duct -which is lined with ciliated epithelium-, from a dorsal diverticulum of the female atrium -lined with a nonciliated epithelium, after Marcus. However, we were unable to make this distinction since both epithelia are non ciliated.

Carbayo et al. (2013) included the specimen MZUSP PL 1008 in their molecular analyses. They identified this specimen as Geoplana hina Marcus, 1951 . Although very alike, the external aspect and the copulatory apparatus of this specimen do not fully match diagnosis of C. hina . See below the section Remarks on Cratera picuia sp. n.

Figures

FIGURE 3. Cratera crioula (Froehlich, 1955). (A): photomicrograph of a sagittal section of the copulatory apparatus of holotype. (B): diagrammatic representation of the copulatory apparatus of specimen F2946 from sagittal sections.

FIGURE 4. Cratera hina (Marcus, 1951). (A): dorsal view of the live specimen F5682. (B): photomicrograph of a sagittal section of penis papilla of specimen F5682; arrowheads point to longitudinal muscle between two circular muscle underlying the papillar epithelium (detail in inset). (C): photomicrograph of a sagittal section of the copulatory apparatus of holotype. (D): photomicrograph of a horizontal section of the penis papilla tip of specimen F5682, showing the ejaculatory duct. (E): photomicrograph of a horizontal section of the copulatory apparatus of specimen F5682, showing glands piercing dorsal epithelium of male atrium and encountering of ovovitelline ducts with female genital duct.