Paraba bresslaui (Schirch, 1929) Silva & Carbayo, 2020

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

publication ID	https://dx.doi.org/10.3897/zookeys.910.39486
publication LSID	lsid:zoobank.org:pub:2C11E2A1-7D5D-42A0-80EC-E5FC618FF47B
persistent identifier	https://treatment.plazi.org/id/D83DB09D-14CC-52D0-9E2E-72F5586B2F52
treatment provided by	ZooKeys by Pensoft
scientific name	Paraba bresslaui (Schirch, 1929)
status	comb. nov.

Treatment

Paraba bresslaui (Schirch, 1929) comb. nov. Figures 5 View Figure 5 , 6 View Figure 6 , 7 View Figure 7 , 8 View Figure 8 , 9 View Figure 9

Geoplana bresslaui Schirch, 1929: 31. Type Locality: Teresópolis, State of Rio de Janeiro, Brazil.

E. M. Froehlich 1955b: 203. [nec Geoplana bresslaui Schirch, 1929, in Riester (1938)].

Pseudogeoplana bresslaui : Ogren and Kawakatsu 1990: 114.

Material examined.

MNRJ 210, holotype, here designated by monotypy: Teresópolis, State of Rio de Janeiro, Brazil. P. Schirch (unknown year). Preserved in 80 % ethanol. Three dimensional (3D) images and virtual sections were obtained by microcomputed tomography.

Diagnosis.

Species of Paraba 25 mm long; dorsal side yellowish green ground color with a narrow median black band; long and narrow prostatic vesicle, inverted ‘U’ -shape; male atrium with 6-8 transverse annular folds; ovovitelline ducts ascend anterior to gonopore; female atrium lined with an epithelium that protrudes into male atrium.

External aspect.

Fixed holotype 25 mm long; body with greatest width in the pharyngeal region, 5 mm. Towards the extremities, the body narrows gently, with the anterior tip being rounded and the posterior end being obtuse (Fig. 5A, C View Figure 5 ). Dorsal side strongly convex; ventral side flat. Dorsum ochre brown, with irregular areas of cream color as a result of fading (Fig. 5A, D View Figure 5 ). Body margins in anterior 1/6 of the body with beige color. Ventral side ochre yellow (Fig. 5C View Figure 5 ).

A single row of eyes contours the anterior first millimeter of the body (Fig. 5E View Figure 5 ); posteriorly they extend for ca. 4 mm, arranged in a row with 2-4 eyes on either side of the body. Further posterior, eyes could not be discerned. Sensory pits are simple invaginations located ventro-marginally in a single row from the very anterior body tip to at least 2 mm posteriorly (Fig. 6A, E View Figure 6 ). Relative position mouth: body length, 66 %. Relative position gonopore: body length, 82 %.

Internal morphology.

Two-millimeter long paired cerebral ganglia, commencing 5 mm posterior to anterior extremity. Ventral nerve plate present (Fig. 7A View Figure 7 ). Longitudinal cutaneous musculature well developed, with fibers gathered in bundles (Fig. 7A, D View Figure 7 ). Cutaneous musculature thickness relative to body height at the pre-pharyngeal region, ~4 %. Cephalic retractor muscle absent.

Mouth opening at the posterior section of the pharyngeal pouch. Pharynx cylindrical (Fig. 7B, C View Figure 7 ), with a dorsal insertion slightly posterior to the ventral one. Short esophagus present. Testes rounded, the largest follicles ca. 200 µm in diameter. They are located dorsally and are arranged in a row of ca. 20 follicles on either side of the body (Fig. 7D View Figure 7 ), each row having up to two testes in the same transverse plane. Most anterior testes are located dorsally to the ovaries and 1 mm posterior to the cerebral ganglia, i.e., at a distance from anterior extremity equivalent to 32 % of the body length; posterior-most testes shortly anterior to the pharyngeal root.

Lateral to the prostatic vesicle, the sperm ducts recurve and then open into a branch of the prostatic vesicle (Fig. 8D View Figure 8 ). Prostatic vesicle with an inverted ‘U’ -shape in lateral view (Fig. 8C View Figure 8 ), with its ascending portion having a sinuous wall, while the descending portion is straight. At its distal most portion, this vesicle bends posteriorly to penetrate the antero-ventral region of the penis bulb. Prostatic vesicle surrounded by a 100 µm thick distinct mass, presumably consisting of muscles and glands. This vesicle is located at anterior portion of the penis bulb, the latter extending 1 mm anterior to the penis papilla.

Inside the penis bulb, the prostatic vesicle communicates with the ejaculatory duct. This duct is horizontally positioned and runs through the penis papilla to open at its tip. Penis papilla cylindrical, with the distal portion truncated in lateral view (Figs 8A, B View Figure 8 , 9A, B View Figure 9 ), but conical in dorsal view (Fig. 9A View Figure 9 ). It fills 2/3rd of the male atrium length. Male atrium broad, with 6-8 transverse, annular folds. Anterior-most fold is the largest and surrounds the basis of the penis papilla. Length of male atrium twice of that of the female atrium.

Ovaries 230 µm in diameter and approximately rounded. They are positioned at 8 mm from anterior extremity of the body, and 1 mm posterior to the cerebral ganglia. They are located above the ventral nerve plate (Fig. 7D View Figure 7 ). Ovovitelline ducts emerge from the dorso-lateral aspect of the ovaries (Fig. 7A View Figure 7 ) and run posteriorly horizontally to the level of the gonopore. Then they ascend obliquely to the sagittal plane and join the common glandular ovovitelline duct immediately above the posterior region of the female atrium. Common glandular ovovitelline duct (~100 µm long) runs ventrally to join the female genital canal, the latter being a ~160 µm projection of the posterio-dorsal region of the female atrium. Female atrium ~1 mm in length and 0.5 mm in height, equivalent of 1/4 of the body height. This female atrium is elongate and is lined with an epithelium with a very high epithelium (~250 µm), typical of epithelia with a stratified aspect, which occupies the whole cavity except for an irregular narrow canal (Fig. 9A, B View Figure 9 ). This female lining epithelium presents a cone-shaped protrusion into the male atrium. The gonopore canal is vertical and 500 µm long.

Distribution.

Municipality of Teresópolis (-22.42, -43.01), State of Rio de Janeiro, Brazil.

Remarks.

The general shape and size of the body agrees with the original description ("length 25 mm; maximum width 8-9 m[m]" ( Schirch 1929) and correct labeling of the specimen as the holotype by monotypy is assumed (Fig. 5B View Figure 5 ). Fading of the body color is normal, especially after 90 years of conservation in a preservative.

The specimen has the characteristics of the subfamily Geoplaninae , albeit the width of the creeping sole could not be ascertained. We assume a wide creeping sole on the basis of the flat ventral side of the specimen.

Further features observed on this species match only one genus of the Geoplaninae , namely Paraba Carbayo et al., 2013, whose diagnosis reads: " Geoplaninae with small-to-medium-sized body, 6-80 mm in length; body slender, with margins nearly parallel; dorsum and ventral side slightly convex; eyes monolobulated; pharynx cylindrical; prostatic vesicle extrabulbar, generally horizontal; penis papilla protrusible, conical; male atrium not folded; ascending portion of ovovitelline ducts lateral to the gonopore canal or to female atrium, joining each other above female atrium; genital canal dorso-anteriorly flexed, arising from the posterior-dorsal region of female atrium; female atrium rounded, clothed with an epithelium with multilayered aspect" ( Carbayo et al. 2013: 523). In view of the internal morphology of the species, herein presented for the first time, it is justifiable to transfer the species to Paraba .

This species only differs from the diagnostic features of Paraba in some details that deserve a comment: (a) the dorsum is not slightly, but strongly convex, (b) the male atrium is not unfolded, but folded, and (c) the female atrium is not rounded, but elongate. These differences probably represent artefacts or intrageneric variation: the two former features (shape of the dorsum and folds of the male atrium) might have been caused by contraction during fixation or, simply, the male atrium is folded. An elongate female atrium is also found in other species of Paraba (namely Pa. franciscana , Pa. rubidolineata ).

Regarding the external aspect, Pa. bresslaui differs from all other congeneric species in the color pattern, consisting of a yellowish green ground color, ornamented with a median black stripe, and beige pigment spots, often elongated and parallel to the main body axis. None of the 14 species of Paraba present a green-yellowish dorsal color with a median black stripe and beige spots stretching longitudinally, as in Pa. bresslaui .

Regarding the internal aspect, there are four species resembling Pa. bresslaui in having a U-shaped prostatic vesicle, namely Pa. cassula (E. M. Froehlich, 1955a), Pa. goettei (Schirch, 1929), Pa. phocaica (Marcus, 1951) and Pa. piriana (Almeida & Carbayo, 2012, in Almeida et al. 2012). However, Pa. phocaica is the only species sharing with Ps. bresslaui the posterior insertion of the genital canal into the female atrium. Both species also share distinct features: an annular fold around the basis of the penis papilla, a male atrium folded, and the general shape of the prostatic vesicle. Apart from body color, however, Pa. bresslaui is distinguished from Pa. phocaica in that the latter species presents a more dorsal entrance of the prostatic vesicle into the penis bulb (vs. ventral as in Pa. bresslaui ), a rounded female atrium (vs. elongate), and a lining epithelium of the female atrium not invading the male atrium (vs. invading it).