Pasipha johnsoni, Negrete, Lisandro & Brusa, Francisco, 2016

Negrete, Lisandro & Brusa, Francisco, 2016, Land flatworms of the genus Pasipha (Platyhelminthes, Geoplanidae) in Argentina, with description of three new species, Zootaxa 4137 (2), pp. 187-210 : 195-200

publication ID	https://doi.org/ 10.11646/zootaxa.4137.2.2
publication LSID	lsid:zoobank.org:pub:94661073-A6EB-4134-B709-BF4ED7AF50EA
DOI	https://doi.org/10.5281/zenodo.6070965
persistent identifier	https://treatment.plazi.org/id/03F24A30-FFC2-FF9C-98FA-EB3E0A99FB5C
treatment provided by	Plazi
scientific name	Pasipha johnsoni
status	sp. nov.

Treatment

Pasipha johnsoni View in CoL sp. nov.

( Figs. 5–9 View FIGURE 5 View FIGURE 6 View FIGURE 7 View FIGURE 8 View FIGURE 9 )

Pasipha sp. 3: Negrete et al. 2014a

Type material. Holotype. MLP-He 6489. Urugua-í Wildlife Reserve, Misiones Province, Argentina, 31.X.2010, L. Negrete, coll.; cephalic region and anterior region at level of ovaries: sagittal sections on 14 slides (8 µm); prepharyngeal region: transverse sections on 5 slides (8 µm); pharynx and copulatory apparatus: sagittal sections on 15 slides (8 µm).

Additional material examined. MLP 6488. Urugua-í Wildlife Reserve, Misiones Province, Argentina, 21.VIII.2009, L. Negrete, coll.; cephalic region and anterior region at level of ovaries: transversal sections on 33 slides (8 µm); pharynx: sagittal sections on 36 slides (6 µm) (immature specimen).

Diagnosis. Dorsum dark grey with two black lateral stripes. Eyes dorsal with clear halos. Pharynx cylindrical. Prostatic vesicle extrabulbar, globose with folded walls, and proximally forked. Male atrium richly folded, three times longer than the female atrium. Ovaries anterior to the anteriormost testes. Distal sections of ovovitelline ducts ventral to the female atrium, joining behind it. Common ovovitelline duct vertical and located behind the female atrium. Female genital canal almost horizontal. Female atrium without folded walls.

Type locality. Urugua-í Wildlife Reserve (25° 59’ S, 54° 05’ W), Misiones Province, Argentina.

Etymology. The specific name is dedicated to Andrés Johnson (1956-2009), eminent naturalist who made a significant contribution to the knowledge of Atlantic Forest biodiversity in Argentina.

External morphology. The body is elongate, with parallel margins, and ovoid in cross section ( Figs. 5 View FIGURE 5 , 7 View FIGURE 7 B). The anterior tip is rounded and the posterior tip ends in a sharp point ( Fig. 5 View FIGURE 5 A, B). The colour pattern of the dorsal surface is dark grey with two black lateral stripes, visible at naked eye (each ~1/10 of body width). They extend along the whole body except in the cephalic region, where pigment is light grey ( Fig. 5 View FIGURE 5 A, B). Towards the body margins, pigment becomes gradually lighter. Ventral surface is light grey. After fixation, the dorsal ground colour becomes paler, but lateral stripes are evenly visible. The eyes, with clear halos, surround the cephalic region uniserially and spread towards body margins in a single row up to 4–6 mm from the anterior tip. Then the eyes spread progressively dorsally in two and three rows ( Fig. 6 View FIGURE 6 ). At the level of pharynx, they are again marginal, uniserial and less numerous, reaching the posterior end of body.

The largest specimen was 40 mm long in vivo ( Fig. 5 View FIGURE 5 A). After fixation, body length ranged from 29 mm to 37 mm, maximum width was 1.7–1.9 mm, and maximum height 1–1.3 mm. The mouth and gonopore were located at a distance of 67% and 81% from the anterior tip, respectively.

Internal morphology. Epidermis, secretions and musculature in the cephalic region. Dorsal epidermis (15 µm height) receives abundant rhabditogen secretion, with rhabdites covering the entire dorsal surface, as well as abundant fine granular erythrophil secretion and less numerous amorphous erythrophil secretions discharge both in dorsal and ventral epidermis. Scarce fine granular cyanophil secretion open through body margins. Ventral epidermis (20 µm height) is ciliated on the creeping sole (90% of body width). Sensory pits (25 µm deep), as simple invaginations, surround the anterior tip and continue toward body margins in a single row up to ~ 2 mm from the anterior tip ( Fig. 7 View FIGURE 7 A). The cutaneous musculature, organized as in the pre-pharyngeal region (see below), is somewhat thicker than at the pre-pharyngeal level (13% of the body height). The thickness of the parenchymatic musculature ranges from 7% to 13%. There is no musculo-glandular specialization in the cephalic region.

Epidermis, secretions and musculature in the pre-pharyngeal region. Abundant rhabditogen cells with erythrophil secretion, numerous cells with fine granular erythrophil secretion and less abundant cells with amorphous erythrophil and cyanophil secretions open through dorsal epidermis (25–30 µm height) and body margins ( Fig. 7 View FIGURE 7 B, C). Ventral epidermis (25 µm height), ciliated in the creeping sole (90% of body width), presents abundant small dermal rhabdites, and receives fine granular erythrophil secretion in less quantity than the dorsal epidermis. Cell bodies of the erythrophil glands are located below the cutaneous musculature. There is no glandular margin ( Fig. 7 View FIGURE 7 B).

The cutaneous musculature consists of three typical layers of Geoplaninae , a thin subepidermal circular layer (2.5 µm thick), an intermediate diagonal layer (5–12.5 µm thick), and an internal thicker longitudinal layer organized in bundles (40–45 µm thick dorsally, 50–70 µm thick ventrally). CMI ranges from 9% to 11%. The parenchymatic musculature consists of a dorsal decussate layer (30–40 µm thick), a supra-intestinal layer and a sub-intestinal transverse layer (25–40 µm thick each) ( Fig. 7 View FIGURE 7 C, D). Dorso-ventral fibres are located among intestinal branches ( Fig. 7 View FIGURE 7 C). PMI ranges from 7% to 10%.

Digestive system. The pharynx (1.2–1.3 mm in length, about 3–4% of body length) is cylindrical, with the dorsal insertion slightly posteriorly displaced, with mouth located in the posterior third of the pharyngeal pouch (1.5–1.7 mm in length) ( Fig. 7 View FIGURE 7 E). The epithelial lining of the outer surface of the pharynx is cuboidal and ciliated, followed by a thin longitudinal subepithelial muscle layer (2.5–5 µm thick) and a subjacent circular layer (10 µm thick). The epithelium of the pharyngeal lumen is columnar and ciliated. The inner pharyngeal musculature consists of a circular subepithelial layer (20–40 µm thick) and a subjacent longitudinal layer (10–25 µm thick). Abundant cells with fine erythrophil and cyanophil granules discharge their secretions onto the pharyngeal epithelium. Cell bodies of these glands are located anterior to the pharynx and extend their necks towards the pharyngeal epithelium. The oesophagus (400–500 µm in length) is lined by a columnar epithelium, followed by a subepithelial circular muscular layer (15–20 µm thick) and a subjacent longitudinal one (10 µm thick). The oesophagus: pharynx ratio is 31–38%.

Male reproductive system. The testes, ovoid in shape, are located just below the supra-intestinal parenchymatic muscular layer, forming two irregular rows on each side of body ( Fig. 7 View FIGURE 7 B, C). They are pre-pharyngeal and extend from behind the ovaries to the vicinity of the pharyngeal root, being located at a distance between 25% and 63% of the body length from anterior end. Testes occupy 18% of the body height. The sperm ducts are medial to ovovitelline ducts in the pre-pharyngeal region, being located between fibres of the sub-intestinal parenchymatic muscular layer ( Fig. 7 View FIGURE 7 B, D). Posterior to the pharynx they are dilated and their lumen is full of spermatozoa, and in the vicinity to the common muscular coat they bend antero-dorsally and to the sagittal plane and open into the forked portions of the prostatic vesicle ( Figs. 8 View FIGURE 8 , 9 View FIGURE 9 B). The extrabulbar prostatic vesicle, located just behind the pharynx ( Fig. 9 View FIGURE 9 A), is globose and consists of two distinctive regions. Both exhibit folded walls with narrow lumen but differ histologically, in the type of glandular secretions that they receive (see below) and anatomically, since the proximal region is proximally forked ( Figs. 8 View FIGURE 8 , 9 View FIGURE 9 A–C). The distal portion of the prostatic vesicle gradually diminishes in diameter and opens into the ejaculatory duct, which has a small portion external to the common muscle coat ( Figs. 8 View FIGURE 8 , 9 View FIGURE 9 C). Once within the common muscle coat, the ejaculatory duct has an ascending sinuous course and opens into the bottom of the male atrium, dorsally displaced ( Figs. 8 View FIGURE 8 , 9 View FIGURE 9 A). The male atrium (2.6 mm in length) is a richly folded cavity with a narrow lumen; its length is three times larger than that of the female atrium ( Figs. 8 View FIGURE 8 , 9 View FIGURE 9 A). The most proximal region presents numerous small folds while the rest of the atrium exhibits larger folds ( Figs. 8 View FIGURE 8 , 9 View FIGURE 9 A).

The lining epithelium of the sperm ducts is cuboidal and ciliated, and no underlying musculature is observed at pre-pharyngeal level, while posterior to the pharynx they exhibit squamous epithelium surrounded by a thin circular muscle layer (5 µm thick). The prostatic vesicle, lined by a ciliated columnar epithelium, is wrapped by a muscle coat with longitudinal and some circular fibres (40–60 µm thick), which is thinner in the proximal region (15–20 µm thick). The epithelium of proximal region of the prostatic vesicle is traversed by abundant fine granular pale erythrophil secretion while its distal part receives abundant coarse granular erythrophil secretion, strongly stained ( Fig. 9 View FIGURE 9 A–C). Cell bodies of both glandular secretions are located in the surrounding parenchyma laterally and anteriorly to the prostatic vesicle. The ejaculatory duct is lined by a ciliated columnar epithelium followed by a circular muscle layer (5–10 µm thick) and a thin subjacent longitudinal (2.5 µm thick). The male atrium is lined in its most proximal region, in which there are small folds, by a columnar and ciliated epithelium ( Fig. 9 View FIGURE 9 D). The rest of the male atrium is lined by a non-ciliated, cuboidal to columnar epithelium. The male atrial epithelium can be differentiated into three regions according to the glandular secretions that discharge into it. The proximal region is traversed by amorphous cyanophil secretion; the median region receives abundant fine granular erythrophil secretion, and the distal region receives abundant fine granular cyanophil secretion ( Fig. 9 View FIGURE 9 A, D, E). The muscularis of the male atrium consists of a subepithelial circular layer (5 µm thick) followed by a longitudinal layer (10 µm thick). The common muscle coat consists of longitudinal fibres (15–30 µm thick) that bend and enter into the atrial folds, but without forming a coherent layer ( Fig. 8 View FIGURE 8 ).

Female reproductive system. The ovaries (300 µm in length and 200 µm high, in the holotype), ovoid in shape, are located ventrally to the intestine, between the sub-intestinal parenchymatic muscle layer and the nervous plate ( Fig. 7 View FIGURE 7 F). They are situated at 7.7 mm from the anterior end (21% of body length). The ovovitelline ducts arise from the dorsal side of the ovaries, and backwards they are located below the sub-intestinal parenchymatic muscle layer at pre-pharyngeal level ( Fig. 7 View FIGURE 7 D). Behind the gonopore they still run below the copulatory apparatus and progressively bend to the sagittal plane. In their distal course the ovovitelline ducts contour the common muscle coat and join in a common glandular ovovitelline duct (250 µm length) which runs vertically behind the female atrium ( Figs. 8 View FIGURE 8 , 9 View FIGURE 9 A, F). The female genital canal is an almost horizontal duct (240 µm length) that connects the common glandular duct to the female atrium ( Figs. 8 View FIGURE 8 , 9 View FIGURE 9 F). The female atrium (850 µm length) is a poorly folded cavity, although there is large fold shared by both atria which hangs from their dorsal walls ( Figs. 8 View FIGURE 8 , 9 View FIGURE 9 A).

The ovovitelline ducts are lined with a cuboidal and ciliated epithelium, followed by a circular muscle layer (5 µm thick). Their distal ascending portions receive secretion from the shell glands. The lining epithelium of the common glandular ovovitelline duct is columnar and ciliated, traversed by abundant secretion from shell glands, followed by a subjacent muscle layer consisting of circular and oblique interwoven fibres (15 µm thick) ( Fig. 9 View FIGURE 9 A, F). The epithelium of the female canal is columnar, followed by a thin muscle layer of circular fibres (5 µm thick). The female atrium is lined by a columnar epithelium and its muscularis consists of a circular layer (5 µm thick) followed by a loosely organized longitudinal layer (10 µm thick). The female canal and atrium receive abundant fine granular erythrophil secretion ( Fig. 9 View FIGURE 9 A, F), and the epithelium of the distal portion of the female atrium is traversed by abundant fine granular cyanophil secretion ( Fig. 9 View FIGURE 9 A). Cell bodies of these glands are located in the surrounding parenchyma outside the common muscle coat. This coat consists of longitudinal fibres (10–15 µm thick). The gonopore canal is lined by a columnar and ciliated epithelium, receiving openings of scarce cyanophil glands with fine granular secretion. Vitellaria are developed only in the mature specimen (holotype), with follicles located dorsal and ventral to the intestinal branches ( Fig. 7 View FIGURE 7 B–D, F).

Parasitism. In the holotype, nematode larvae were found in the parenchyma of the anterior body region and in the pharyngeal region.