Freddius tricaudatus Takeda & Kajihara 2018, sp. nov.
Creators: name: Takeda, Naoya
name: Kajihara, Hiroshi
Publisher: name: Zenodo
Year: 2018
Subjects: Biodiversity
Taxonomy
Animalia
Platyhelminthes
Rhabdocoela
Cheliplanidae
Freddius
Freddius tricaudatus

description: Freddius tricaudatus sp. nov.
(Figs 2–5)
Material examined. Holotype: ICHUM 4832, adult, whole mount, 43°01′16″N, 144°50′13″E, Akkeshi, Hokkaido, Japan, intertidal sand, 15 June 2012. Paratypes: ICHUM 4829–4831, three adults, whole mount, same data as holotype; ICHUM 4833–4835, three adults, fluorescent phalloidin stained, same data as holotype; ICHUM 4836–4838, three adults, whole mount, from type locality, 24 June 2013.
Description. Living animal body approximately 900 µm long and 130 µm wide. Pair of hooks present, asymmetrical in structure (Figs 2, 3), one 12–14 µm and the other 10–11 µm in length, each 3–4 µm wide and semi-cylindrical in shape, anteriorly articulated with three movable nails, 9–11 µm in length (Fig. 3); longer hook possesses a pair of additional lateral nails, 12–16 µm long, which are (i) anteriorly directed, (ii) articulated at both sides of the hook near its posterior end, (iii) longer than the anterior movable nails, and (iv) equipped with a pair of spines at their midpoint (Fig. 3). Paired auxiliary apparatuses present between hooks, tapered rod in shape, 4 µm long (Fig. 3C, F). Proboscis gland 55 µm long, 20 µm wide, situated posterior to proboscis (Fig. 2). Eyes absent (Fig. 2). One testis 100 µm long, 30 µm wide, not divided into follicles, situated posterior to proboscis gland (Fig. 2). Multiple sacs of unknown function, arranged posterior to testis (Fig. 2). Pharynx 100 µm long, 50 µm wide, posterior to sacs (Fig. 2). Mouth opening anterior to pharynx (Fig. 4A). Male copulatory organ, posterior to pharynx (Figs 2, 4), roughly tubular; anterior part bulbous and muscular; posterior part with cone-shaped cirrus spines, 20 µm long, 10 µm wide (Figs 4B, 5). Genital pore opening on ventral side of body, posterior to cirrus spines (Fig. 4). Single ovary 50 µm long, 20 µm wide, situated posterior to genital pore (Fig. 2). Pair of yolk glands 300 µm long and 25 µm wide, situated posterior to ovary (Fig. 2). Posterior end of body trifurcated, with tail-shaped serial beads in the middle (Fig. 2).
Etymology. The specific name refers to the three tails in the new species.
Remarks. The new species is undoubtedly a member of Cheliplanidae; it possesses proboscis with side pieces and a postrostral bulb, without separate lateral gland sacs, one pair of proboscis hooks, and characteristics that are shared among all the members of the family (Karling 1983); in addition, the structure of the genital organs in this species is similar to that in other members of the family. In cheliplanids, the proboscis hooks consist of a symmetrical pair of simple, curved spines, which, however, are not elaborate enough to be articulated like in the new species. The morphology of the proboscis hook in this species is so peculiar that it cannot be classified with certainty into any of the existing four genera in the family (Tyler et al. 2006 –2013). Therefore, we propose to establish a new genus in the Cheliplanidae family to accommodate this new species.
description: Published as part of Takeda, Naoya & Kajihara, Hiroshi, 2018, A New Genus and Five New Species of Kalyptorhynchia (Platyhelminthes: Rhabdocoela) Discovered in Northern Japan, pp. 1-11 in Species Diversity 23 (1) on page 2, DOI: 10.12782/specdiv.23.1, http://zenodo.org/record/4583800