Elthusa Schioedte & Meinert, 1884

Hadfield, Kerry A., Tuttle, Lillian J. & Smit, Nico J., 2017, Elthusawinstoni sp. n. (Isopoda, Cymothoidae), a new fish parasitic isopod from Hawaii, ZooKeys 661, pp. 125-135 : 125

Genus Elthusa Schioedte & Meinert, 1884

Elthusa Schioedte & Meinert, 1884: 337.- Bruce 1990: 254.- Trilles 1994: 164.- Trilles and Randall 2011: 453-454.

Type species.

Livoneca emarginata Bleeker, 1857, by monotypy ( Schioedte and Meinert 1884).

Remarks.

Diagnostic characters for Elthusa include a weakly vaulted body; pleonite 1 as wide as or slightly narrower than pleonite 2; posterior margin of cephalon not trilobed; wide pleon; antennula shorter than antenna, bases not in contact (varying from close together to wide apart); and pleopods all simple, lamellar. A revised diagnosis of the genus was provided by Bruce (1990) as well as Trilles and Randall (2011).

Elthusa can be regarded as one of the most morphologically varied cymothoid genera, with many Elthusa species still requiring detailed study and redescription. The antennula position (being close together or far apart), shape of the cephalon anterior margin, as well as the width of the pleon and pleonite 5 are some of the varying characters noted within species of this genus ( Bruce 1990). This variation can cause confusion in genus identifications and may lead to incorrect species placement if not taken into account with all of the other genus characters.