Castrada paradisea, 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 : 11-12

Castrada paradisea n. sp.

( Figs. 5 A–5B)

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. Four serially-sectioned specimens, one of which designated holotype ( MNCN, no. 4.01/54), and eight whole mounts, five of which designated paratype (HU, nos. 396–399; 422).

Etymology. The species name refers to the third cantica of Dante’s Devine Comedy: Paradiso (Italian; Lat.: Paradisum).

Description. Animals have an average length of 0.8 mm and are lanceolate with bluntly-rounded frontal and caudal ends. Eyes are lacking. All specimens are a dull white colour and most have faint red spots. Zoochlorellae are absent. Adenal rhabdite glands with small, elongated rhabdites fill the body anterior to the pharynx. Basophilic glands, not observed in live animals, but conspicuously present in the serial sections, are interspaced between the rhabdite glands. In one specimen, two brown eggs were observed caudo-laterally to the pharynx.

The ciliated epidermis is cellular and is 5–6 µm thick. Cilia are about 6 µm long. As in many other species of Castrada , the epidermal cells consist of a basal, more darkly-stained part containing the nuclei, and an apical more weakly-coloured part (e.g. Luther 1946; Willems et al. 2005). Dermal rhabdites have not been observed.

The pharynx rosulatus is identical with that of most other species of Castrada (see Luther 1904, 1963). Nephridiopores are combined with the buccal tube.

The paired, globular to club-shaped testes lie anterior to the pharynx. The overall organization of the male genital system is similar to that of Castrada purgatorialis n. sp. The copulatory bulb is oviform, contains two types of coarse-grained prostate secretion and is provided with two spirally-running muscle layers. The sclerotized, funnelshaped ejaculatory duct apparently lacks a distal sphincter and enters a narrow male atrium, which enters the atrium copulatorium through a weak sphincter. The large blind sac and the caudal wall of the atrium copulatorium are armed with numerous, relatively small spines of equal size (around 4–5 µm). A small, central part without spines divides the blind sac into a distal and a proximal part. The copulatory bursa only bears spines on its relatively wide, distal part, while the proximal part is filled with several bean-shaped spermatophores. The atrium copulatorium, blind sac and copulatory bursa are all lined with a low, anucleated epithelium and surrounded by well-developed circular muscles. A muscular septum surrounds all male organs (copulatory organ, atrium copulatorium with blind sac and copulatory bursa). The atrium copulatorium enters the common genital atrium through a large sphincter. The common genital atrium is lined with a high, nucleated and ciliated epithelium.

The female system is similar to that of C. purgatorialis n. sp. However, the distinction between oviduct and the cellular seminal receptacle is less clear in C. paradisea n. sp. Whether female glands are present or not, is not fully clear in the sections.

In contrast with the conspicuous accessory bursa of C. purgatorialis n. sp., the accessory bursa of this species is a relatively simple but large, rostral protrusion of the common genital atrium. Its epithelium is low, anucleated and has no cilia. The paired uteri stretch laterally on both sides of the pharynx.

Diagnosis. Species of Castrada without zoochlorellae, with a copulatory bursa with spined stalk, containing spermatophores, and an atrium copulatorium with a large blind sac armed with uniform small spines (4–5 µm). Ejaculatory duct a simple, sclerotized funnel. Large accessory bursa a simple protrusion of the common genital atrium.

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

Figures

FIGURE 5. Castrada paradisea n. sp. (A) Habitus from a live animal. (B) Reconstruction of the atrial organs from the right hand side.