Freddius tricaudatus, Takeda & Kajihara, 2018

Takeda, Naoya & Kajihara, Hiroshi, 2018, A New Genus and Five New Species of Kalyptorhynchia (Platyhelminthes: Rhabdocoela) Discovered in Northern Japan, Species Diversity 23 (1), pp. 1-11 : 2

publication ID	https://doi.org/ 10.12782/specdiv.23.1
publication LSID	lsid:zoobank.org:pub:A9B333A2-FD81-476A-A805-D280C2194964
DOI	https://doi.org/10.5281/zenodo.5527054
persistent identifier	https://treatment.plazi.org/id/E2DDD4C0-94F5-4FAC-AD0B-C93532AD9653
taxon LSID	lsid:zoobank.org:act:E2DDD4C0-94F5-4FAC-AD0B-C93532AD9653
treatment provided by	Felipe
scientific name	Freddius tricaudatus
status	sp. nov.

Treatment

Freddius tricaudatus View in CoL sp. nov.

( Figs 2–5 View Fig View Fig View Fig View Fig )

Material examined. Holotype: ICHUM 4832 View Materials , adult, whole mount, 43°01′16″N, 144°50′13″E, Akkeshi , Hokkaido, Japan, intertidal sand, 15 June 2012 GoogleMaps . 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 View Fig , 3 View Fig ), 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 View Fig ); 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 View Fig ). Paired auxiliary apparatuses present between hooks, tapered rod in shape, 4 µm long ( Fig. 3C, F View Fig ). Proboscis gland 55 µm long, 20 µm wide, situated posterior to proboscis ( Fig. 2 View Fig ). Eyes absent ( Fig. 2 View Fig ). One testis 100 µm long, 30 µm wide, not divided into follicles, situated posterior to proboscis gland ( Fig. 2 View Fig ). Multiple sacs of unknown function, arranged posterior to testis ( Fig. 2 View Fig ). Pharynx 100 µm long, 50 µm wide, posterior to sacs ( Fig. 2 View Fig ). Mouth opening anterior to pharynx ( Fig. 4A View Fig ). Male copulatory organ, posterior to pharynx ( Figs 2 View Fig , 4 View Fig ), roughly tubular; anterior part bulbous and muscular; posterior part with cone-shaped cirrus spines, 20 µm long, 10 µm wide ( Figs 4B View Fig , 5 View Fig ). Genital pore opening on ventral side of body, posterior to cirrus spines ( Fig. 4 View Fig ). Single ovary 50 µm long, 20 µm wide, situated posterior to genital pore ( Fig. 2 View Fig ). Pair of yolk glands 300 µm long and 25 µm wide, situated posterior to ovary ( Fig. 2 View Fig ). Posterior end of body trifurcated, with tail-shaped serial beads in the middle ( Fig. 2 View Fig ).

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.