Epikopais mystax, 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 : 136-139

Epikopais mystax sp. nov.

Figures 6–7

Material examined. All off South Island , New Zealand. Holotype. Female (3.0 mm), Bounty Trough, stn S151, 45°45.8'S, 174°30.5'E, epibenthic sled, 26 September 1979, 1586 m, RV Tangaroa ( NIWA 23790 ). Paratypes. Female (2.7 mm, dissected), Bounty Trough, stn S153, 45°21.1'S, 173°35.8'E, epibenthic sled, 27 September 1979, 1386 m, RV Tangaroa ( NIWA 23791 ). Female (undissected), type locality ( NIWA 23792 ) .

Description. Female. Body length 2.1 times width of pereonite 2; cuticle not highly calcified. Cephalon smooth; anterior cephalic flanges flap-like. Frons with long SS. Pereonites 1–5 anterior margins with SS; anterolateral margins of pereonites 3–4 with anteriorly facing lobes. Pereonite 6 and 7 ventrally without ornamentation. Pleon length 0.7 times proximal width.

Antenna 1 article 1 length 2.1 times width, distal end with narrow extension, surface with 2 penicillate setae and 1 SS, distal margin with 5 sensillate RS and 1 penicillate seta; article 2 length 0.4 times article 1 length, distally with 4 sensillate RS; article 4 with 1 penicillate seta. Antenna 2 article 1 lateral margin with 1 sensillate RS; article 2 length equals article 1 length, distolateral margin with 3 sensillate RS; article 3 length 1.4 times article 1 length, with 4 sensillate RS, scale with 1 SS; article 4 length 1.3 times article 1 length, with 1 SS.

Mandible spine row present, with 3 short spines; molar distally with 2 serrate setae; right molar with distal denticle. Maxilla 1 lateral and mesial margins with fine SS; lateral lobe width 1.5 times mesial lobe width, distal margin with few fine SS, 3 RS, 4 dentate RS, 4 pectinate RS, and 1 bi-serrate RS, mesial lobe distally with many fine SS and 2 long pectinate setae. Maxilla 2 lateral lobe margins with fine SS; middle lobe width equals lateral lobe width; mesial lobe width 2.0 times lateral lobe width, mesial and distal margins with fine SS, distally also with 6 blunt SS, 3 toothed setae and 1 long pectinate seta. Maxilliped coxa rectangular, length 1.3 times width, and 0.3 times basis length, with 2 RS; basis length 3.6 times width, with 4 RS; endite with 3 coupling hooks, 4 toothed setae, 4 fan setae and few fine SS; palp article 1 with cuticular scales, distomesial margin with 1 RS; article 2 length 4.4 times article 1 length, lateral margin with cuticular scales and 1 distal RS, mesial margin with 3 distally pappose setae; article 3 length 2.3 times article 1 length, lateral margin with 1 RS, mesial margin with 2 SS and 7 distally pappose setae; article 4 length 0.9 times article 1 length, with 2 distally pappose setae; article 5 length 1.1 times article 1 length, lateral margin with 1 SS distally with 3 distally pappose setae and 1 SS; epipod length 1.6 times width, margins with cuticular scales.

Pereopod 1 broken; ischium length 4.1 times width, inferior margin with 1 SS, lateral surface with 2 sensillate RS (on opposable surface), superior margin with 2 RS; merus length equals width, inferior margin with 3 SS, distosuperior margin with 2 SS; carpus length 3.4 times width, inferior margin with 5 SS, superior margin with 1 SS; propodus length 4.3 times width, inferior margin with 5 SS, superior margin with 2 SS; dactylus length 3.8 times proximal width, superior margin with 2 SS.

Operculum length 2.1 times proximal width, distally with medial excision and veined lamellar extension, medial keel with row of short, plumose setae, proximally with 7 SS, distal surface with few scattered SS, lateral margins with numerous plumose setae, extending proximally towards keel. Pleopod 3 endopod length 1.4 times width, with 3 long plumose setae; exopod with 4 long plumose setae and 1 SS. Pleopod 4 endopod length 1.2 times width. Pleopod 5 length equals width.

Uropod protopod length 1.3 times width, margins with cuticular scales, lateral margin with 2 plumose setae, distal margin with 4 SS and 2 plumose setae; exopod 0.4 times protopod length, with 2 SS; endopod 0.6 times protopod length, with 5 penicillate setae and 2 SS.

Males are not known from this species.

Remarks. Epikopais mystax sp. nov. is distinguished from the other species of Epikopais by: the length of pereonites 1–4 being more elongate when compared to the natasome than seen in the other species of this genus; a row of simple setae along anterior margin of pereonite 5; and the frons with numerous long setae. E. mystax sp. nov. is most similar to Epikopais waringa sp. nov., but differs on several features. E. mystax sp. nov. has many more elongate setae on the frons and the body is much narrower than in E. waringa sp. nov. Pereonites 1–4 are more elongate in comparison to pereonites 5–7 in E. mystax , while in E. waringa sp. nov. pereonites 1–4 are shorter in comparison to pereonites 5–7. The operculum keel of E. mystax sp. nov. is more elongate and less triangular than in E. waringa sp. nov.

Distribution. Bounty Trough, South Island, New Zealand, between 1386–1586 metres.

Etymology. Mystax is Greek, meaning hair on the upper lip, in reference to the many long setae present on the frons.

Figures

Figure 6. Epikopais mystax gen. nov., sp. nov. a–c, female holotype, 3.0 mm (NIWA 23790); d–j, female paratype, 2.7 mm (NIWA 23791): a, dorsal view; b, lateral view; c, cephalon; d, right antenna 1; e, right antenna 2; f, left mandible; g, left mandibular molar; h, right mandibular molar; i, right mandible; j, left maxilla 1. Scale bar = 1 mm, for dorsal and lateral views only.

Figure 7. Epikopais mystax gen. nov., sp. nov. a–c, e, g, h, female paratype, 2.7 mm (NIWA 23791); d, f, i, female holotype, 3.0 mm (NIWA 23790): a, right maxilla 2; b, right maxilliped; c, right maxilliped palp; d, left pereopod 1; e, left pleopod 3; f, operculum; g, right pleopod 4; h, left pleopod 5; i, right uropod.