Thoracostomopsis Ditlevsen, 1918

De Souza, João V. & Maria, Tatiana F., 2023, Taxonomic review of Thoracostomopsidae (Nematoda, Enoplida): state of the art, list of valid species and dichotomous keys, Zootaxa 5361 (4), pp. 463-496 : 487-488

Genus Thoracostomopsis Ditlevsen, 1918

Ditlevsen (1918) established a new genus for an organism collected in Little Belt, Denmark, Thoracostomopis barbata Ditlevsen, 1918 based on a single female.Although, this genus is very similar to Thoracostoma , which have the tail constricted before the tip, it differs by having the head covered with a cephalic capsule much narrower than the adjacent part of the body; the buccal cavity is provided with a thin, acute spear to the proximal end of which the chitin-intima of the pharynx is attached. Filipjev (1927) described three species for the genus: Thoracostomopsis ditlevseni Filipjev, 1927 , which was later transferred to Metaphanoderma ditlevseni (Filipjeb, 1927) Platonova, 1984b ; Thoracostomopsis galeata Filipjev, 1927 with description of only female, showing a strong cephalic capsule; and Thoracostomopsis longissima Filipjev, 1927 bearing small spicules. Subsequently, Thoracostomopsis carolae Inglis, 1964 were described and T. barbata was invalidated because its description was based on an immature female and a true spear in the buccal cavity of were not be evidenced ( Inglis, 1964). Nevertheless, a male of T. barbata was described by Allgén (1935) and subsequently a detailed description of this species was provided by Blome (1982). Thoracostomopsis doveae Warwick, 1970c was the most recent species described for this genus and it is distinguished from other species by long spicules, presence of gubernaculum, cephalic capsule bearing uniformly rounded lobes, different mandible structure and larger overall size.

Diagnosis from Smol et al. (2014): Mandibles are reduced and three onchia are elongated and wrapped around each other to form an axial spear-like structure. The cephalic capsule is strongly lobed and the incisions are very broad. The spicules can be long and slender or short and stout with or without a gubernaculum. The cephalic setae vary in length. Tubular precloacal supplement usually present. Marine.

Number of valid species: 4

1. Thoracostomopsis barbata Ditlevsen, 1918 (Danish Belt Sea) new status— type species 2. Thoracostomopsis carolae Inglis, 1964 ( South Africa)

3. Thoracostomopsis doveae Warwick, 1970c ( North Sea )

4. Thoracostomopsis longissima Filipjev, 1927 (Barents Sea)

SPECIES INQUIRENDA

1. Thoracostomopsis galeata Filipjev, 1927 (Barents Sea)