Ligia Fabricius, 1798

Ariyama, Hiroyuki & Hiki, Kyoshiro, 2024, A morphological and molecular study of Ligia exotica Roux, 1828 (Crustacea: Isopoda: Ligiidae) from Japan, with descriptions of two new species, Zootaxa 5453 (4), pp. 451-486 : 459-460

Genus Ligia Fabricius, 1798

[Japanese name: Funamushi-zoku]

Ligia Fabricius, 1798: 301 .— Jackson, 1922: 683.

Ligyda Rafinesque, 1815: 101 .— Richardson, 1905: 673.

Lygia Roux, 1828: 57 (unnumbered).— Dana, 1853: 716.— Dana, 1855: pl. 49. Geoligia Dollfus, 1893b: 343 .

Megaligia Verhoeff, 1926: 348 .

Nesoligia Verhoeff, 1926: 348.

Euryligia Verhoeff, 1926: 348.

Aspidoligia Verhoeff, 1926: 348 .

Ligia (Pogonoligia) Jackson, 1927: 130 .

Ligia (Megaligia) .— Van Name, 1936: 48.

Ligia (Nesoligia) .— Van Name, 1936: 54.

Ligia (Hirtiligia) Van Name, 1936: 57 .

Ligia (Euryligia) .— Jackson, 1941: 7.

Type species: Oniscus oceanicus Linnaeus, 1767 , subsequent designation by Latreille (1810).

Diagnosis: Body oval or oblong oval, moderately convex dorsally. Head frontal margin rounded, eyes large and convex. Pereonites relatively broad, posterodistal corners acutely projected in posterior segments. Pleonites more or less narrower than pereonite 7, posterodistal corners produced. Pleotelson broader than long, distal margin triangular or arcuate. Antennula very small, with 3 articles; terminal article rudimentary. Antenna strong and elongated, exceeding third pereonite. Mandibles with incisor, lacinia mobilis different in left and right, setal row and molar, lacking palp. Maxillipedal palp 5-articulated. Pereopods ambulatory, with many robust setae, pereopods 1–6 gradually increasing in length posteriorly; basis of pereopods wide, dactylus distinctly bi-unguiculate. Penile papillae paired, situated on distal end of male pereonite 7 sternum. Pleopods flattened, each with exopod and endopod; male endopod of pleopod 2 biarticulated, tip of article 2 modified to form appendix masculina. Uropod elongated, peduncle not produced mediodistally; both rami narrow, styliform, subequal in length.

Remarks: The above diagnosis cannot be described in more detail, because morphological information is insufficient in most of the Ligia species. Three of four genera established by Verhoeff (1926) were reduced to subgenera of Ligia by Van Name (1936), and two other subgenera, Pogonoligia Jackson, 1927 and Hirtiligia Van Name, 1936, were also proposed ( Jackson 1927; Van Name 1936). However, belonging to the subgenera has not been discussed in all the Ligia species ( Andersson 1960); therefore, these subgeneric names should not be applied to the genus.