Four new species of splanchnotrophid copepods (Poecilostomatoida) parasitic on doridacean nudibranchs (Gastropoda, Opistobranchia) from Japan, with proposition of one new genus

Abstract

Four new species of splanchnotrophid copepods are described based on specimens collected from 5 species of doridacean nudibranchs from coastal waters of Japan. They belong to 3 genera, one of which, Majimun gen. n., is new. The parasites and their hosts are as follows: Ceratosomicola japonica sp. n. ex Hypselodoris festiva (A. Adams); Splanchnotrophus helianthus sp. n. ex Thecacera pennigera (Montagu); Splanchnotrophus imagawai sp. n. ex Trapania miltabrancha Gosliner & Fahey; and Majimun shirakawai gen. et sp. n. ex Roboastra luteolineata (Baba) and Roboastra gracilis (Bergh). Ceratosomicola japonica sp. n. is the fifth species of Ceratosomicola and is characterized by the shape and armature of the prosome in females. Both Splanchnotrophus helianthus sp. n. and Splanchnotrophus imagawai sp. n. are differentiated from 4 known congeners by the absence of posterolateral processes or lobes on the prosome in females, and the females of these 2 new species are separated from each other by the shape and armature of the genito-abdomen, the mandible, and the swimming legs. Majimun gen. n. is distinguished from other splanchnotrophid genera by the segmentation of the antennule as well as the combination of the following characters in females: 2 postgenital somites and the shape of the antenna, the mandible and the swimming legs.

Lomanoticola nishiharain. sp., a New Species of Copepod Parasitic on the Facelinid Nudibranch,Sakuraeolis enosimensis(Baba, 1930), from the Seto Inland Sea, Western Japan, Including Histological Observations of the Female Lateral Body Process

“…Huys (2001) demarcated Splanchnotrophus from Lomanoticola and considered the latter a distinct genus based on the following female characters: egg sacs with anteriorly and posteriorly directed lobes and attaching at about mid-length to the genital apertures; excessive development of the lateral processes; the presence of a lobate endopod on leg 2; and the reduction of the caudal rami which bear a spatulate seta V. However, recently described members of both genera are often not separated by this combination of characters. For instance, S. helianthus Nagasawa, 2012 andS. imagawai Uyeno andNagasawa, 2012 bear the styliform seta V on the caudal rami (Uyeno and Nagasawa, 2012).…”

“…Parasitic on the Facelinid Nudibranch, Sakuraeolis enosimensis (Baba, 1930), from the Seto Inland Sea, Western Japan, Including Histological Observations of the Female Lateral Body Process cies of Ismaila, four species of Ceratosomicola, two species of Arthurius, and two species of Splanchnotrophus have been added since Huys' (2001) revision of the family (Haumayr and Schrödl, 2003;Salmen et al, 2008a, b;Uyeno and Nagasawa, 2012;Anton et al, 2016). In addition, the genus Majimun Uyeno and Nagasawa, 2012 was proposed for a single species from Japanese waters (Uyeno and Nagasawa, 2012). Currently, the family contains 31 species in six genera, all of which occur in temperate to tropical regions.…”

“…Remarks. The new species is concerned to assigned to the genus Lomanoticola based on the following characters of the adult female, i.e., the prosome bears lateral processes which are shorter than the body, the prosome lacks processes on dorsal or ventral sides, the presence of the genito-abdomen, and the mandible represented by a curved blade (Huys, 2001;Uyeno and Nagasawa, 2012). Prior to the discovery of L. nishiharai n. sp.…”

Description of four new endoparasitic species of the family Splanchnotrophidae (Copepoda, Poecilostomatoida) from nudibranch and sacoglossan gastropod hosts

“…Since its last taxonomic revision (Huys 2001), the family includes five recognized genera: Arthurius Huys, 2001, Ceratosomicola Huys, 2001, Lomanoticola Scott and Scott, 1895, Splanchnotrophus Hancock and Norman, 1863and Ismaila Bergh, 1867. Recently, it was enlarged by a sixth genus-Majimun Uyeno and Nagasawa, 2012-based on a Communicated by P. Martinez Arbizu * Roland F. Anton rolandanton1@gmail.com 1 single new species discovered in Japan (Uyeno and Nagasawa 2012). The currently best-studied splanchnotrophid genus Ismaila is known only from the coasts of the American continent (Anton and Schrödl 2013a;Haumayr and Schrödl 2003;Ho 1981;Huys 2001;Schrödl 2003).…”

A preliminary observation of a Trichodina sp. (Ciliophora: Peritricha) on the skin of Elysia singaporensis (Sacoglossa, Plakobranchidae)

“…on Oreochromis niloticus (Linnaeus, 1758) and O. aureus (Steindachner, 1864), T. cancilae Asmat, 2001 on Xenentodon cancila (Hamilton, 1822), T. gulshae Asmat et al, 2003 on Mystus cavasisus (Hamilton, 1822), T. domergue Wallengren, 1897 on Neogobius melanostomus Pallas 1814, and T. gobii Raabe, 1959 on Solea aegyptiaca arenaria, Linnaeus, 1758) (see Uzmann & Stickney, 1954;Aksit et al, 2008). For sea slugs, there have been numerous reports of parasites such as copepods (see Jensen, 1987Jensen, , 1990Schrödl, 1997Schrödl, , 2002Abad et al, 2011;Uyeno & Nagasawa, 2012), Turbellaria flatworms (Sudo et al, 2011) and sea spiders (Arnaud, 1978), but none of Trichodina thus far. Therefore, the researchers chose to observe the presence of Trichodina on sea slug as it has a short lifespan parasite and can be found in the general aquatic animals.…”