Lagenopolycystis mandelai Willems & Artois, n. sp.

Lagenopolycystis mandelai Willems & Artois n. sp.

(Fig. 5 C–E)

Lagenopolycystis n. sp. 2 in Tessens et al. (2014)

Locality. iSimangaliso Wetland Park, Sodwana Bay, Jesser Point (lighthouse) (27°32'28.4"S, 32°40'47.9"E), coarse-grained sand from swirl holes on rocky plateau in mid-eulittoral, covered with the acoel Symsagittifera macnaei (Du Bois-Reymond Marcus, 1957) Kostenko & Mamkaev, 1990 from a highly-exposed, steep beach, December 10, 2009 (type locality); same locality, fine-grained sand from swirl holes on rocky plateau in mideulittoral, covered with the acoel S. macnaei, December 10, 2009.

Material. Two animals studied alive. One whole mount, designated holotype (SMNH, type-8858).

Etymology. Species name in honour of Nelson Mandela (1918–2013), famous anti-apartheid activist, Nobel Peace Prize laureate (1993, together with Frederik Willem de Klerk) and former president of South Africa (1994– 1999).

Diagnosis. Species of Lagenopolycystis with ± 115-µm-long prostate stylet type III, with proximal funnel-like part and distal tubular part, which is bent perpendicularly at 2/3 and has a blunt, club-shaped end. Slightly bent, needle-shaped accessory stylet type II ± 65 µm long and attached to prostate stylet type III.

Description. Habitus and internal organisation similar to that of Lagenopolycystis peresi (Brunet, 1965) Artois & Schockaert, 2000. In live animals, the proboscis is approximately 1/4 of the total body length, although appearing slightly shorter in Fig. 5 C because of stretching of the observed individual. Animal colourless, ± 0.9 mm long (measured on whole mount), with two eyes.

The prostate stylet type III (Fig. 5 C–D: pst3) is 115 µm long and rather complex. Proximally it is funnelshaped, 30 µm wide, with a thickened rim on one side. This rim shows a subtle striation and ends in a rounded knob. Following the funnel-shaped part, the stylet is straight, but bends perpendicularly at 2/3 of its length. It ends in a blunt, club-shaped part. The accessory stylet type II (Fig. 5 C–D: ast2) is attached to the thickened rim of the prostate stylet through a narrow bridge that ends in a comma-shaped part, which constitutes the proximal rim of the accessory stylet proper. The accessory stylet curves away from the club-shaped end of the prostate stylet. It is hook shaped and 65 µm long. A rather large, globular accessory vesicle type II opens close to the accessory stylet. The prostate vesicle type III can barely be seen on the whole mount as it is very small and probably (partly) obscured by the prostate stylet.

The female duct receives the oviduct and a large female bursa. A seminal receptacle could not be observed.

Discussion. Although some diagnostic features could not be observed (e.g. parallel cone retractors, 4+1 retractor system, seminal receptacle), L. mandelai n. sp. fits the diagnosis of the taxon Typhlopolycystidinae Evdonin, 1977 (see Artois & Schockaert 2000). In addition, the molecular phylogenetic analysis of Tessens et al. (2014) shows that this species belongs to the monophyletic taxon Lagenopolycystis Artois & Schockaert, 2000. Within Typhlopolycystidinae, only representatives of Lagenopolycystis and Typhlopolycystis Karling, 1956 have both a prostate stylet type III and an accessory stylet type II, whereas species of Myobulla Artois & Schockaert, 2000 and Sabulirhynchus Artois & Schockaert, 2000 possess a prostate stylet type III, and species of Limipolycystis Schilke, 1970 and Brunetorhynchus Schockaert et al., 2014 have an accessory stylet type II (see Artois & Schockaert 2003; Artois et al. 2012; Schockaert et al. 2014). Furthermore, species of Typhlopolycystis and Limipolycystis are characterised by the presence of a pear-shaped seminal receptacle (Karling 1956, 1978; Brunet 1965; Schockaert & Karling 1975; Noldt & Reise 1987; Artois & Schockaert 2005). According to Brunet (1965), a seminal receptacle is absent in L. peresi, but both the description and figures show a strong sphincter on the bursal stalk. Detailed study of sectioned material of L. peresi shows a short, blind-ending, sclerotized tube that is distally surrounded by strong circular muscles (Artois & Schockaert 2000: p. 157). This structure is found exactly at the location of the seminal receptacle in species of Typhlopolycystis and therefore both structures were considered to be homologous by Artois & Schockaert (2005: p. 115). A similar structure is also found in other undescribed representatives of Lagenopolycystis (own unpublished data). However, since no sectioned material is available for L. mandelai n. sp., the presence of a seminal receptacle cannot be confirmed.

The overall construction of the hard parts (pst3 + ast2) of the new species is similar to that of L. peresi, albeit with some obvious differences. In both species the prostate stylet type III has a clear, funnel-like part proximally, with the accessory stylet attached to it at the transition to a more or less tubular part. However, the prostate stylet of L. peresi only bends slightly distally, while in L. mandelai n. sp. it bends perpendicularly. Furthermore, the prostate stylet of L. mandelai n. sp. is approximately twice the size of that of L. peresi (Brunet 1965: 53–69 µm). The accessory stylets of both species are highly similar, but clearly shorter in L. peresi (40–43 µm, measured on drawings of Brunet 1965).