Castrada purgatorialis, Steenkiste, Niels Van, Tessens, Bart, Krznaric, Kathleen & Artois, Tom, 2011

Steenkiste, Niels Van, Tessens, Bart, Krznaric, Kathleen & Artois, Tom, 2011, Dalytyphloplanida (Platyhelminthes: Rhabdocoela) from Andalusia, Spain, with the description of four new species, Zootaxa 2791, pp. 1-29 : 10-11

Castrada purgatorialis n. sp.

( Figs. 4 A–4B)

Locality. Doñana National Park, Provincia de Huelva, Spain (37°04’23”N, 6°22’28”W). Laguna de la FAO: permanent water body with submersed vegetation (05/04/2008) (type locality).

Material. Observations on several live animals. Two whole mounts, both designated as paratypes (HU, nos. 394–395) and one serially-sectioned specimen, designated as the holotype ( MNCN, no. 4.01/53).

Etymology. The species epithet refers to its morphological resemblance to C. infernalis Papi, 1951 . Purgatorio (Italian; Lat.: Purgatorium) and Inferno (Italian; Lat.: Infernum) are two of the three canticas of Dante’s Divine Comedy.

Description. Animals are about 1.2–1.3 mm long, lanceolate with a more bluntly-rounded front end and without eyes. Rostrally, rhabdite glands containing small, elongated rhabdites are present. Zoochlorellae dispersed throughout the whole body give the animal a bright green colour. A maximum of seven brown eggs were observed inside the specimens.

The cellular epidermis is about 5 µm thick with 4 µm-long cilia. Dermal rhabdites have not been observed.

The pharynx rosulatus contains eosinophilic and basophilic glands and is situated in the first body half between 25–40% (ph in Fig. 4 A). Similarly to other species of Castrada Schmidt, 1861 , the prepharyngeal cavity is separated from the buccal tube by a sphincter (see Luther 1946, 1963; Papi 1959). This buccal tube (bt in Fig. 4 B) is lined with a ciliated and nucleated epithelium not differing from the body epithelium. Proximally, it receives the protonephridial ducts to form the excretory cup. A second sphincter around the mouth surrounds the buccal tube distally.

The paired, globular testes are rather small and lie in front of the pharynx, ventral to the vitellaria. Vasa deferentia and extracapsular seminal vesicles have not been observed in live specimens, nor in the serial sections. The construction of the male genital system is characteristic for the taxon Castrada : atrium copulatorium receiving a copulatory bursa, the copulatory bulb and a blind sac with spines. The copulatory bulb is oviform and apparently surrounded by two spiral muscle layers. In live specimens two types of prostate glands could be seen entering the copulatory bulb proximally, completely filling it with two different coarse-grained secretions. These could not be retrieved in the serial sections. Distally, the copulatory bulb contains the sclerotized and funnel-shaped ejaculatory duct, which opens into a small, muscular male genital atrium. A strong sphincter surrounds the distal part of the ejaculatory duct. Dorsal to the copulatory bulb, a relatively large, dual blind sac surrounded by circular muscles and provided with numerous spines, enters the atrium copulatorium. Although slightly variable, most spines are of equal size except for two regions with conspicuously larger spines. In a dorsal protrusion of the sac (x in Fig. 4 B), a group of very long spines, measuring ± 18 µm up to 22 µm maximum, contrasts with the other spines of the blind sac. The average length of the small spines is about 3–4 µm. In the other part of the blind sac, closer to the copulatory bulb, another group of longer spines with a maximum length of 12 µm is present (y in Fig. 4 B). All have a broad base and many of the small spines have a bent tip. Ventral to the copulatory bulb, the atrium copulatorium receives the copulatory bursa. A bursal stalk is absent. The proximal two thirds of the low bursal epithelium bears small spines (± 1.5 µm) becoming slightly larger in the most proximal part (± 2 µm), but still clearly smaller than those of the blind sac. The whole copulatory bursa is provided with a well-developed circular muscle layer. The atrium copulatorium is relatively large and has a low epithelium without nuclei. On its caudal wall, where the blind sac enters, a field of tiny sclerotized spines (size less than 1 µm) appears to be present. The atrium copulatorium has strong circular muscles and is separated from the common genital atrium by a large sphincter. The entire male genital system consisting of the spined blind sac, the copulatory bulb and the copulatory bursa, is surrounded by a muscular septum.

The single ovary lies caudal from the male genital system. The oviduct protrudes distally to form the seminal receptacle. This seminal receptacle consists of a number of large, nucleated cells. Neither a lumen nor sperm were observed. Before the oviduct and the seminal receptacle enter the female duct, the vitelloduct joins the female system. The vitellaria stretch dorsolaterally at both sides beyond the pharynx. The female duct is lined with a high, nucleated epithelium and provided with circular muscles. Ventrally, it receives eosinophilic female glands. The female duct enters the common genital atrium caudally. The latter has a high, nucleated epithelium with cilia, very similar to the body epithelium, and is also surrounded by a circular muscle layer.

The same ciliated epithelium and muscle layer continue in a large accessory bursa, which enters the common genital atrium from the rostral side. Proximally this bursa receives two large vesicles filled with a basophilic, granular secretion of which the origin and function remain unknown. Paired uteri with a rather high, degenerated epithelium enter the common genital atrium just rostrally from the atrium copulatorium. Up to seven eggs have been observed in the animal.

Diagnosis. Species of Castrada with zoochlorellae, a spined copulatory bursa, an atrium copulatorium with a large blind sac armed with small spines (3–4 µm) and two fields of large slender spines (± 12 and 20 µm respectively). Ejaculatory duct a simple, sclerotized funnel. Large accessory bursa with two vesicles filled with glandular secretion.

Discussion. See the discussion following the remarks on C. infernalis Papi, 1951 .

Figures

FIGURE 4. Castrada purgatorialis n. sp. (A) Habitus from a live animal. (B) Reconstruction of the atrial organs from the left hand side.