A new species of freshwater isopod (Sphaeromatidea: Sphaeromatidae) from an inland karstic stream on Espíritu Santo Island, Vanuatu, southwestern Pacific

摘要: Exosphaeroides quirosi is described from a karstic stream and its associated cave sink located 390 m above sea level 23.5 km inland the east coast of Espiritu Santo (Vanuatu, SW Pacific ocean). This first purely freshwater sphaeromatid isopod reported an oceanic island, new example colonization island habitat by typically marine taxon. E. differs any other representative family in peculiar condition displayed exopod pleopod 4, which has falcate outline, distinctly longer than corresponding endopod, medial margin proximal segment produced into foliaceous endite. Seemingly, sexual dimorphism expressed presence/absence setulose fringe on pereopods not been recorded sphaeromatid. Even though 4 fusion pattern pleonites—with complete incorporation pleonite 1 to rest pleonites—could suggest genus accommodate species, it included here broad Exosphaeroma s. l. cluster, most sphaeromatids seem derive. done with caveat that incertae sedis until such time as comprehensive revision related genera undertaken. appears be -derived species unusual remainder pleon; these features being regarded species-level apomorphies within morphologically diverse genus.