Leptognathia G.O. Sars, 1882

Larsen, Kim & Shimomura, Michitaka, 2007, Tanaidacea (Crustacea: Peracarida) from Japan. II. Tanaidomorpha from the East China Sea, the West Pacific Ocean and the Nansei Islands, Zootaxa 1464, pp. 1-43 : 14-15

Genus Leptognathia G.O. Sars, 1882

Gender. Feminine.

Type species. Tanais breviremis Lilljeborg, 1864 .

Diagnosis. Female. Cheliped fixed finger and dactylus simple. Uropodal exopod with one article.

Remarks. Although a full scale revision of the Leptognathia is not within the scope of this study, a few changes are justified here. The genus Leptognathia is generally considered paraphyletic- rather than a monophyletic taxon ( Sieg 1986a; Larsen 2005) and is often treated as a repository for ‘unidentifiable’ and poorly described deep-sea tanaidomorphans. According to Anderson et al. (2006) the genus Leptognathia currently contain 39 morphologically heterogeneous species of which most are very poorly described.

Bird and Holdich (1984) initiated the first serious attempt of a solution by removing and organizing a number of leptognathid species into separate genera. Sieg (1986b), by redescribing the type species L. breviremis Lilljeborg, 1864 , provided a much needed platform for a continuation of this effort, by giving a reference point to a more precise diagnosis to the Leptognathiidae . A more restrictive diagnosis of the Leptognathiidae was given by Larsen & Wilson (2002) and of Leptognathia by Larsen (2005), but a number of problems still plagues this genus. One of these problems is a large number of poorly described species, of which many do not correspond to the narrower definition of Leptognathia sensu Larsen. In order to identify the Leptognathia species described below, several of these non- Leptognathia sensu stricto species were identified and are here removed from the Leptognathia , although final genus designation for many species will have to await a more detailed revision.

The following species are removed from Leptognathia as they posses a biarticulated uropodal exopod: Leptognathia arctophylax ( Norman & Stebbing, 1886) ; L. distincta Kudinova-Pasternak, 1981 ; L. elegans Kudinova-Pasternak, 1965 ; L. greveae Kudinova-Pasternak, 1976 ; L. mironovi Kudinova-Pasternak, 1981 ; L. parabranchiata Kudinova-Pasternak, 1977 *; L. paraelegans Kudinova-Pasternak, 1970 ; L. tuberculata Hansen, 1913 and L. voeringi (G.O. Sars, 1877) , A new leptognathidean genus Biarticulata is here erected to accommodate these species. L. tuberculata may not belong to the Leptognathiidae at all as the structure of the molar is unknown.

Another new leptognathidean genus Forcipatia is erected to receive L. rotundicauda Kudinova-Pasternak, 1970 ; Leptognathia longimanus Larsen, 2005 ; and L. sp G. (currently undescribed, G. Bird, pers. comm.).

Leptognathia angustocephala Kudinova-Pasternak, 1975 a; L. birsteini Kudinova-Pasternak, 1965 ; L. lineate Shiino, 1978 ; linearis ( Hansen, 1913); L. microcephala Kudinova-Pasternak, 1977 *; and L. zenkevitchi Kudinova-Pasternak, 1970 are completely removed from the family Leptognathiidae as they have broad mandibular molars.

Also removed from the family is L. profunda Hansen, 1913 , which have a spiniform exopodal process and probably belongs to Araphura Bird & Holdich, 1984 .

Leptognathia vinogradovae Kudinova-Pasternak, 1970 ; L. indivisa ( Hansen, 1913) and L. paramanca Lang, 1958 , which have uniramous uropods, are also removed from the family.

Furthermore, L. dentifera G.O. Sars, 1896 and L. uncinata Hansen, 1913 both possess a biarticulated uropodal exopod and a spiniform process on the uropodal basal articles as well as a cheliped carpal shield, and are here transferred to Tumidochelia (see above).

These removals reduced the number of species in the Leptognathia to eight verified species: L. bamberi n. sp; L. breviremis Lilljeborg, 1864 ; L. breviremoides Sieg, 1986 b; L. glandiceps Shiino, 1978 ; L. gyreae Larsen, 2005 ; L. longa ( Kudinova-Pasternak, 1982) ; L. manca G.O. Sars, 1882 ; and L. vitjazi ( Kudinova-Pasternak, 1982) and nine species inceta sedis, which may belong to Leptognathia but were the molar structures are not known: L. langi Kudinova-Pasternak, 1970 ; L. zezinae Kudinova-Pasternak, 1973 ; L. acanthifera Hansen, 1913 ; L. crassa Hansen, 1913 ; L. tenella Hansen, 1913 ; L. ventralis Hansen, 1913 ; L. abyssorum ( Dollfus, 1897) ; L. luykeni Vanhöffen, 1914 ; L. vanhoeffeni Gutu, 1972 .