Hausera hauseri Leal-Zanchet & Souza

Leal-Zanchet, Ana Maria, de Souza, Stella Teles & Ferreira, Rodrigo Lopes, 2014, A new genus and species for the first recorded cave-dwelling Cavernicola (Platyhelminthes) from South America, ZooKeys 442, pp. 1-15 : 3-7

Taxon classification Animalia Tricladida Dimarcusidae

Hausera hauseri Leal-Zanchet & Souza sp. n.

Material examined.

Holotype. MZUSP PL. 1562: coll. R. Ferreira, 22 March 2011, Crotes cave, Felipe Guerra, RN, Brazil - sagittal sections on five slides.

Paratypes. Crotes cave, Felipe Guerra, RN, Brazil. MZU PL.00142: coll. R. Ferreira, 22 March 2011 - sagittal sections on 10 slides; MZU PL.00148: coll. R. Ferreira, 22 March 2011 - transverse sections on 9 slides; MZU PL.00149: coll. R. Ferreira, 05 June 2010 - anterior region: transverse sections on 12 slides, posterior region: sagittal sections on 20 slides.

Diagnosis.

Hausera hauseri can be distinguished from other species in the Dimarcusidae by (1) the numerous testicular follicles arranged in two irregular rows next to the margins of the body, extending from the level of the ovaries to the posterior end of the body; (2) the ovoid bulbar cavity with a posteriorly directed diverticulum into which the sperm ducts open; (3) a short and narrow transition region between the bulbar cavity and the ejaculatory duct; (4) the ovovitelline ducts arising from the lateral surface of the ovaries.

Description.

Live specimens unpigmented and eyeless (Fig. 6). Head truncate; posterior tip pointed (Figs 6-7). Preserved specimens up to 7.5 mm long and 2 mm wide (Table 1). Mouth and gonopore located at the posterior body third (Table 1). Body margins almost parallel (Figs 6-8). After fixation, anterior and posterior tips rounded (Fig. 8).

Epidermis (Figs 9-10). Columnar, ciliated epithelium, with abundant xanthophil, rhabidtogen secretion (rhammites), both dorsally and ventrally, being more densely distributed at the dorsal surface (Fig. 9). It also receives secretions of other four types of glands: (1) xanthophil, coarse granular secretion; (2) cyanophil amorphous secretion; (3) heavily stained cyanophil, fine granular secretion; (4) erythrophil, fine granular secretion (Figs 9-10). In addition, glands with heavily stained xanthophil, fine granular secretion open at the body margins and medially at the anterior and posterior tips of the body. Cilia more densely arranged on the ventral body surface (Fig. 10).

Cutaneous musculature (Figs 9-10). Two layers, viz. a thin subepithelial circular layer, followed by a thicker layer of longitudinal muscle. Dorsal and ventral cutaneous musculatures show similar height in the pre-pharyngeal region (13-15 µm thick). In the anterior region of the body, the ventral musculature (35 µm thick) is thicker than the dorsal one (9 µm thick).

Sensory organs (Fig. 11). Head with a pair of lateral sensory organs beginning about 140 µm after the anterior tip. They are lined with densely ciliated columnar epithelium, highly innervated, with insunk nuclei and receive few openings of secretory cells. The cutaneous musculature is very thin at the level of the sensory organs.

Pharynx (Fig. 12). Cylindrical; 0.9 mm long; it is located in the posterior third of the body. Pharynx and pharyngeal lumen lined with cuboidal ciliated epithelium with insunk nuclei. Three types of pharyngeal glands, viz. cells with coarse granular xanthophil secretion, cells with cyanophil amorphous secretion and less numerous cells with fine granular erythrophil secretion. Cell bodies of the pharyngeal glands located in the mesenchyme, mainly anterior and laterally to the pharynx. Outer musculature of the pharynx constituted of a thin subepithelial layer of longitudinal muscle, followed by a thin layer of circular muscle, each about 5 µm thick. Inner pharyngeal musculature composed of a thick subepithelial layer of circular fibres (about 25-28 µm thick), followed by a layer of longitudinal fibres (about 10 µm thick).

Intestine (Figs 19, 22, 23). Anterior intestinal trunk extending onto the posterior part of the brain (Figs 19, 23). Posterior intestinal trunks anastomose and communicate with the reproductive system through a genito-intestinal duct (Fig. 22). The part of the intestine that meets the genito-intestinal duct is lined with a tall columnar epithelium composed of cells with cyanophil cytoplasm and cells with coarse granular, erythrophil secretion; its lumen contains sperm and a small amount of erythrophil secretions (Fig. 22). Some spermatozoids are absorbed by the intestinal epithelium.

Male reproductive system (Figs 13-18). Numerous testicular follicles, 60-70 µm in diameter, arranged in approximately two irregular rows laterally to the intestinal diverticles, near body margins (Fig. 13). Testes extend from the level of the ovaries to the posterior end of the body (Figs 13-14). Sperm ducts form spermiducal vesicles laterally to the pharynx, diminishing in diameter laterally to the male copulatory apparatus (Fig. 15). They ascend, forming a loop, and then turn anteriad. Sperm ducts separately penetrate the penis bulb (Fig. 15) and open into the posteriorly directed diverticulum of the large bulbar cavity, in close proximity to each other (Fig. 16). Bulbar cavity single, ovoid, communicating with the ejaculatory duct through a short and narrow transition section (Figs 17-18). Ejaculatory duct opening at the tip of the conical and symmetrical penis papilla. The latter occupies almost the entire male atrium (Figs 13-15, 17-18).

Sperm ducts lined with a ciliated, cuboidal epithelium, underlain by a circular muscle layer. The large penis bulb consists of a loose connective tissue with weak interwoven muscle fibres (Figs 13-15, 17). Bulbar cavity lined with a ciliated, columnar epithelium, and coated with a subepithelial circular muscle layer, followed by a longitudinal muscle layer. Numerous glands with intrabulbar cell bodies and amorphous, cyanophil secretion open into the bulbar cavity. The bulbar cavity contains sperm and cyanophil secretion (Fig. 16). The transition part between the bulbar cavity and the ejaculatory duct is lined with a non-ciliated, cuboidal epithelium, the cells of which show an irregular height. A layer of circular muscle fibres surrounds the epithelial lining of the transition section. Ejaculatory duct lined with non-ciliated, cuboidal epithelium with irregular height, and surrounded by a subepithelial layer of circular muscle, followed by a layer of longitudinal muscle. This duct receives a xanthophil, fine granular secretion from intrapapillar glands. Penis papilla lined with a ciliated, columnar epithelium that becomes flat towards the tip of the papilla. Muscularis of penis papilla composed of a subepithelial layer of circular fibres and a layer of longitudinal fibres. Glands with amorphous, cyanophil secretion and with amorphous, xanthophil secretion open through the epithelial lining of the penis papilla. Both glands show intrapapillar cell bodies. Male atrium lined with a ciliated, high columnar epithelium, the cells of which have an irregular height (Fig. 17). The male atrial muscularis is constituted of a subepithelial layer of circular muscle, followed by a layer of longitudinal muscle. Glands with fine granular, cyanophil secretion and less numerous xanthophil glands with amorphous secretion open into the male atrium.

Female reproductive system (Figs 18, 19-22). Vitellaria poorly developed, located between intestinal branches. Ovaries, 70 µm - 100 µm in diameter, situated dorso-medially to the nerve cords, at about 0.6 mm from the anterior tip and close to the brain (110 µm posteriorly to the brain) (Fig. 19). Ovovitelline ducts arising from the lateral surface of the ovaries (Fig. 20) and running backwards dorsally to the nerve cords. At about the level of the gonopore, the ovovitelline ducts turn dorso-medially and form a common ovovitelline duct that is dorso-anteriorly directed (Figs 18, 21). Common ovovitelline duct opening into a female genital duct. The latter communicates with the male atrium and through a genito-intestinal canal with the intestine. The genito-intestinal canal is ventro-posteriorly directed (Figs 18, 22).

Ovovitelline ducts lined with ciliated, cuboidal epithelium, receiving the secretion of shell glands in their most posterior sections (Figs 18, 21). Common ovovitelline duct lined with ciliated, cuboidal or columnar epithelium, underlain by a circular muscle layer; it receives the secretion of shell glands (Fig. 18). These glands have a xanthophil, fine granular secretion (Fig. 21). Female genital duct and genito-intestinal canal lined with ciliated, cuboidal epithelium, receiving an amorphous, cyanophil secretion. The muscularis of the female genital duct and the genito-intestinal canal consists of a layer of circular fibres.

Etymology.

The new species is dedicated to the late Prof Dr Josef Hauser SJ.

Geographical distribution.

Known only from the type-locality, Felipe Guerra (Crotes cave), Brazil.

Variability.

Vitellaria well-developed in paratype MZU PL.00148 and poorly developed in paratypes MZU PL.00142 and PL.00149. In paratype MZU PL.00148, the anterior region of the body is subcylindrical in transverse section (Fig. 23) and shows a ventral median slit, posteriorly to the brain, where abundant cyanophil secretion is discharged (Fig. 24). In this paratype, the anterior intestinal branch extends slightly anterior to the brain. A short branch of each ovovitelline duct may extend anterior to the ovaries at least in paratype MZU PL.00148.