Pseudogeoplana schirchi (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

Pseudogeoplana schirchi (Schirch, 1929) Figures 25 , 26

Geoplana maximiliani Schirch, 1929: 30; taf. 2, fig, 10. Type locality: Teresópolis, State of Rio de Janeiro, Brazil.

Pseudogeoplana schirchi : Ogren and Kawakatsu 1990: 159. nom. nov.

Material examined.

Type material. Single holotype received on loan in 70 % ethanol and, subsequently, three-dimensional (3D) images and virtual sections of syntype MNRJ 217 were obtained by microcomputed tomography. MNRJ 217, holotype, here designated by monotypy: Teresópolis, State of Rio de Janeiro, Brazil. P. Schirch Coll (unknown). Sagittal sections of anterior extremity on 97 slides; horizontal sections of pre-pharyngeal region on 15 slides. Remaining part of body preserved in 80 % ethanol.

External aspect.

Fixed holotype measured 45 mm long, 6 mm wide and 0.9 mm high. Elongated body, with parallel margins; anterior extremity tapers, posterior rounded. Dorsum convex, ventral side flat. Dorsum has yellow olive color, except in some parts where epithelium is lost (Fig. 25B ). Ventral side brown grey with some darker regions. Relative position of mouth: body length, 58 %.

Internal morphology.

Creeping sole comprised ~88 % body width. Histological sections of holotype are of poor quality. Cutaneous musculature comprises three layers: a subepithelial circular layer, followed by a diagonal layer of decussate fibers and a clearly distinguishable innermost longitudinal layer. Muscle fibers of the longitudinal layer (90 µm thick dorsally; 70 µm thick ventrally) arranged into bundles (Fig. 26A ). No muscle modifications at the anterior extremity of the body.

Mouth situated at a distance from the root of the pharynx equivalent to 56 % of the pharyngeal pocket length (Fig. 26B ). Pharynx cylindrical, occupying ~90 % of pharyngeal pocket. Esophagus, apparently absent. Copulatory apparatus not developed, neither are testes or ovaries.

Remarks.

Schirch did not provide any measurement or description of the specimen he studied but illustrated its dorsal aspect (Fig. 25A ). The specimen presents parallel body sides, whereas the figure shows a slightly lanceolate specimen. This situation casts some doubts on the labeling (as is the case of Ps. blaseri , see above). The specimen was apparently dehydrated for an uncertain period. This might explain the differences in body shape.

Most features diagnosing the subfamily Geoplaninae were observed in the holotype, namely, creeping sole covering most of ventral surface, mouth posterior to mid-body, and a well-developed cutaneous musculature organized into bundles. The immaturity of the specimen makes it impossible to know the position of the testes.

The specimen collected in Teresópolis was identified by Schirch as Geoplana maximiliani Schultze & Müller, 1857 (currently placed in Pseudogeoplana ), originally from Blumenau, State of Santa Catarina, Brazil. Froehlich (1959) considered the shape and color pattern of Schirch’s specimen as compatible with Schultze and Müller’s species, but refrained from confirming its conspecificity because the internal morphology of the specimens from both localities was unknown, plus they were collected far from each other ( Froehlich 1959). Ogren and Kawakatsu (1990) endorsed Froehlich’s opinion and gave a new name, namely Pseudogeoplana schirchi , to the specimen from Teresópolis to avoid further confusion. As no further morphological details could be observed, the species will remain in Pseudogeoplana .

Figures

Figure 25. Pseudogeoplana schirchi (Schirch 1929), Holotype. A Original illustration of Ps. schirchi by Schirch (1929) B dorsal view of fixed holotype.

Figure 26. Pseudogeoplana schirchi (Schirch 1929). Holotype. A Photomicrograph of a sagittal section of anterior extremity B virtual sagittal section showing pharyngeal region, pixel size: 9 µm.