Epikopais, Merrin, 2009

Merrin, Kelly L., 2009, Epikopais gen. nov. (Isopoda: Asellota: Munnopsidae), a new genus of munnopsid isopod with three new species from the south-western Pacific., Memoirs of Museum Victoria 66 (1), pp. 129-145 : 129-130

Epikopais gen. nov.

Type species. Epikopais poorei sp. nov., here designated. Diagnosis. Cephalic frons short, laterally rounded; cephalon anterior flanges present; pereonites 1–4 margins with simple setae, dorsal spines absent; pereonites 5–7 lateral margins without elongate spines or jagged edges. Pleon without dorsal and anterolateral spines. Antennae positioned closely together, centrally; antenna 1 article 1 with one distal point, lateral flange absent; antenna 2 article 1 without anterolateral spine. Mandible incisor rounded, with no defined cusps; spine row either present or absent; lacinia mobilis and palp both absent; mandibular fossa curved along lateral margin of mandible; molar smaller than condyle, narrowing distally. Maxilla 2 middle and lateral lobes each distally with 4 long pectinate setae. Pereopod 2 ambulatory, not enlarged; pereopods 5 and 6 carpi expanded, flattened, sub-circular; propodi expanded, flattened, oar-like; pereopods 5–7 ischia superior margin, carpi and propodi inferior and superior margins each with row of plumose setae. Operculum large, with prominent medial keel, lateral margins setose; pleopod 4 exopod with one plumose seta; pleopod 5 simple lobe. Uropods biramous, with large exopod.

Species included. Epikopais aries ( Vanhöffen, 1914) comb. nov.; Epikopais mystax sp. nov.; Epikopais poorei sp. nov.; and Epikopais waringa sp. nov.

Remarks. Epikopais gen. nov. can be distinguished by the combination of: the short laterally rounded cephalic frons; the absence of dorsal spines; the lack of a mandibular palp; the mandibular fossa, which curves along the lateral margin of the mandible; and the biramous uropods with a prominent exopod.

The laterally rounded shape of the cephalic frons is unique within the Ilyarachninae . In Ilyarachna , Notopais and Bathybadistes Hessler and Thistle, 1975 , the cephalic frons is wide and almost rectangular in shape, and lack the lateral roundness found in Epikopais . In Aspidarachna Sars, 1897 , the cephalic frons is very narrow with distance between the antennae and the labrum the smallest of all the Ilyarachninae . The shape of the mandibular fossa is also unique in the Ilyarachninae . The general shape of the mandibular fossa in this subfamily is angular and does not curve along the lateral margin of the mandible as it does in Epikopais .

Like Epikopais , Notopais and Echinozone Sars, 1897 also lack a mandibular palp and have biramous uropods. In addition to the differences found in the cephalic frons and the mandibular fossa, Epikopais can be distinguished from Notopais as it lacks the pronounced spine on the first article of antenna 2, and it can be distinguished from Echinozone as it lacks dorsal spines.

The only previously described species of this genus, Epikopais aries , is based on a single specimen collected from Antarctica and originally place in Aspidarachna , by Vanhöffen (1914). This species was then moved to Echinozone by Hessler and Thistle (1975). Comparing the holotype of E. aries with the other species of Epikopais shows that this species belongs in Epikopais .

Epikopais is known from Antarctica, south-western Australia and New Zealand, at depths between 385–1586 metres.

Etymology. Epikopais is derived from the Greek word epikopos, meaning furnished with oars, in reference to the natatory pereopods of these animals.