Obama itatiayana (Schirch, 1929)

Silva, Marcos Santos & Carbayo, Fernando, 2020, X-ray microcomputed tomography applied to the taxonomic study of rare material: redescriptions of seven of Schirch's Brazilian species of land planarians (Geoplanidae, Platyhelminthes), ZooKeys 910, pp. 1-42 : 1

Obama itatiayana (Schirch, 1929) Figures 1 , 2 , 3

Geoplana itatiayana Schirch, 1929: 34. Type locality: Teresópolis, State of Rio de Janeiro, Brazil.

Geoplana itatiayana : Riester 1938: 64-66.

Obama itatiayana : Carbayo et al. 2013: 523. comb. nov.

Material examined.

Type material. Teresópolis, State of Rio de Janeiro, Brazil. P. Schirch Coll 1916. Each syntype was given an additional identification with a letter, A-C. MNRJ 216A: Body preserved in 80 % ethanol. MNRJ 216B: Body preserved in 80 % ethanol. MNRJ 216C: Three dimensional (3D) images and virtual sections were obtained by microcomputed tomography. Transverse sections of anterior extremity on 27 slides; horizontal sections of ovaries region on 39 slides; transverse sections of pre-pharyngeal region on 28 slides; sagittal sections of pharynx region on 111 slides and sagittal sections of copulatory apparatus region on 77 slides. Remaining part of body preserved in 80 % ethanol.

Diagnosis.

Species of Obama ~43-53 mm long; dorsal color traffic yellow, interspersed with pearl gold specks; esophagus 16 % of pharynx length; prostatic vesicle of inverted-J shape, with an intrabulbar portion; male atrium measuring 4 % of body length and twice as long as female atrium; penis papilla tapered, shorter than male atrium; female atrium funnel-shaped, 1.4 % body length.

External aspect.

Fixed, syntype C measured ~43 mm long, 7 mm wide and 1.6 mm high. Elongated body, with margins parallel; anterior end approximately rounded, posterior tapering (Fig. 1A ). Dorsum convex, ventral side flat. Ground color of dorsum traffic yellow interspersed with pearl gold specks, thus resembling ocellated color of ocelot Leopardus pardalis . Ventral side lemon yellow (Fig. 1B ).

The monolobate eyes are distributed on the anterior tip of the body, encircling the apex of the anterior tip. Posteriorly, the eyes spread onto the dorsum to occupy a band on either side of the body, with a maximum of 22 % of the body width, near region of the ovaries; towards posterior extremity they become less numerous. Sensory pits are simple invaginations 40 µm deep, located ventro-marginally in a single row that surrounds anterior extremity and continues posteriorly up to at least 13 mm of body length, as measured from anterior margin. Relative position mouth: body length, 56 %; relative position gonopore, 75 % in syntype C.

Internal morphology.

Creeping sole comprising 93 % of body width. Abundant rhabditogen cells and glands producing erythrophil granules pierce dorsal and marginal epidermis; glands producing amorphous orangish-to-reddish secretion pierce marginal epidermis. Glandular margin is composed of glands producing erythrophil granules. Cutaneous musculature comprises three layers, viz., a subepithelial circular layer, followed by two diagonal layers with decussate fibers, and then a well-developed innermost layer of longitudinal muscles. Muscle fibers of longitudinal layer (45 µm thick dorsally; 75 µm thick ventrally) are arranged into bundles with 23-78 fibers each. Cutaneous musculature thickness relative to body height in pre-pharyngeal region, 10 % (Fig. 2A, C ). Three parenchymal muscle layers, i.e. a dorsal layer of decussate diagonal fibers, a supraintestinal layer of transverse fibers, and a subintestinal layer with transverse fibers. Ventral nerve plate present (Fig. 2A, B ).

Mouth situated at a distance from root of pharynx equivalent to 40 % of pharyngeal pocket length. Pharynx bell-shaped. Esophagus 500 µm in length (Fig. 3A, B ). Outer pharyngeal musculature consists of one-fiber-thick layer of longitudinal muscle, followed by a layer of circular muscle (15 µm thick) with longitudinal fibers interspersed. Inner pharynx musculature consisting of a subepithelial layer of circular fibers (50 µm thick) interspersed with longitudinal fibers.

Testes ~250 µm in diameter; the follicles are dorsally located between the dorsal parenchymal muscle layer and supraintestinal parenchymal layer (Fig. 2C ). Anteriormost testes at a distance from the anterior extremity of the body equivalent to 11 % of body length; posteriormost testes are anterior to the pharynx, and at a distance equivalent to 46 % of body length. Efferent ducts run between the oviducts and dorsally to the nerve plate. Efferent ducts communicate with the latero-proximal region of the prostatic vesicle (Fig. 3C ). Prostatic vesicle divided into an anterior, extrabulbar half running dorsally, and a posterior, intrabulbar half having the shape of an inverted J (Fig. 3A ). Anterior half of prostatic vesicle with folded wall and lined by a 50 µm high columnar ciliated epithelium which is pierced by glands producing erythrophil granules. Intrabulbar half of vesicle lined with a 30 µm high epithelium; this intrabulbar half pierced by glands producing erythrophil granules being more intensely stained than those in the anterior half. Prostatic vesicle surrounded by a 50 µm thick layer of muscle fibers variously oriented, mainly, diagonal and circular. Prostatic vesicle continues as ejaculatory duct within the penis papilla. This duct curves ventrally to open at the tip of the penis papilla. Ejaculatory duct lined with an erythrophil, 5 µm high ciliated epithelium and surrounded by a circular muscle layer (12 µm thick). Penis papilla conical, with dorsal insertion shifted posteriorly and lined with an 80 µm high columnar epithelium, which is pierced by glands producing erythrophil granules. This epithelium is surrounded by a 100 µm thick coat of muscles consisting of interlaced circular and longitudinal fibers (Fig. 3C ).

Male atrium 1.7 mm long (4 % of body length), not folded, partially occupied by the penis papilla. Male atrium lined with a 15 µm high non-folded columnar epithelium, which is pierced by the openings of abundant glands producing erythrophil granules (Fig. 3A, C ). Male atrium covered by a 12 µm thick layer of circular and diagonal muscle fibers, best visible in its ventral region.

Ovaries ovoid, ~400 µm in maximum length, situated above the ventral nerve plate (Fig. 2B ), situated at a distance from anterior extremity equivalent to 30 % of the body length. Ovovitelline ducts emerge from the lateral portion of the ovaries. Anterior to the gonopore region, the oviducts curve dorso-medially and, subsequently, join to form a common glandular ovovitelline duct, the latter located dorsally to the female atrium (Fig. 3C ). Shell glands pierce the distal portion of the ovovitelline ducts. Common glandular ovovitelline duct 300 µm long and running ventrally to enter the female genital canal. Common ovovitelline duct and female genital canal lined by a ciliated epithelium, which is surrounded by a 10 µm thick layer of circular muscle (Fig. 3A, C ).

Female atrium 750 µm long, funnel-shaped, with its posterio-dorsal portion receiving the female genital canal. Female atrium lined with a 50-400 µm high epithelium; this epithelium presents a stratified aspect and its free surface is indented (Fig. 3A, C ). Female atrial epithelium is pierced by the openings of abundant glands, producing erythrophil granules, and surrounded by a weak muscle layer of circular fibers that is contiguous with that on the common muscle coat. Male atrium: female atrium ratio, 2:1.

Common muscle coat consists of interwoven circular and longitudinal muscle fibers enveloping the unpaired portion of the prostatic vesicle, male and female atria, and part of the common glandular ovovitelline duct.

Distribution.

Municipality of Teresópolis (-22.42, -43.01) and Itatiaia (-22.41, -44.65), State of Rio de Janeiro, Brazil.

Remarks.

The three syntypes A, B, C, and individuals studied by Riester (1938) are very similar to each other in their external aspect. Syntype C and Riester’s specimens are also similar in their internal organs, namely the shape of the pharynx and the copulatory apparatus.

Riester (1938) redescribed the species from additional specimens. Froehlich (1955b) synonymized Geoplana duca Marcus, 1951, from São Paulo and Mogi das Cruzes (state of São Paulo) with G. itatiayana . However, body color and details of the male and female atria of G. duca do not match those of O. itatiayana . In this regard, we disagree with Froehlich’s taxonomic action. A revision of the taxonomic status of G. duca is, therefore, desirable.

A fourth putative type specimen of O. itatiayana , viz., specimen MNRJ 8906, does not conform to the original description as its body is narrower, the dorsum more convex and has a pearl orange midstripe and a pair of paramedian pale brown stripes, external to which the color is beige gray (Fig. 4A ). The pharynx and copulatory apparatus of this specimen (Fig. 4B ), as revealed from µCT-derived virtual sections, resemble O. itatiayana , but the specimen is incompletely mature. The vial of this specimen also contains a label reading " Geoplana itatiayanensis ", as well as another reading " G. itatiayana ". We suspect that at some point during curatorial handling this individual was mislabeled and confounded with the types of O. itatiayana .

Figures

Figure 1. Obama itatiayana (Schirch 1929), syntype C A dorsal view B ventral view C original drawing by Schirch (1929).

Figure 2. Obama itatiayana (Schirch 1929). Syntype C A photomicrograph of a transverse section of pre-pharyngeal region B photomicrograph of horizontal section of ovarian region C photomicrograph of horizontal section of testicular region.

Figure 3. Obama itatiayana (Schirch 1929). Syntype C A µCT-derived image. Virtual sagittal section of pharynx and copulatory region, pixel size: 6.3 µm B photomicrograph of sagittal section of pharynx C photomicrograph of sagittal section of copulatory apparatus.

Figure 4. Specimen MNRJ 8906 mislabeled as O. itatiayana A in dorsal view B virtual sagittal section of pharynx and incipient copulatory apparatus, pixel size: 10 µm.