Myopiarolis novaecaledoniae ( Poore and Brandt, 1997 ) Bruce, 2009

Bruce, Niel, 2009, New genera and species of the marine isopod family Serolidae (Crustacea, Sphaeromatidea) from the southwestern Pacific, ZooKeys 18 (18), pp. 17-76 : 56-58

Myopiarolis novaecaledoniae ( Poore and Brandt, 1997) , comb. n.

Fig. 19

Caecoserolis novaecaledoniae Poore and Brandt, 1997: 161 , figs 7–10 (part).

Material. Holotype, paratypes and all original non-type specimens: all re-identified as M. novaecaledoniae except as discussed below; details in Poore and Brandt (1997).

New material: 3 (14.6 mm), New Caledonia, 24°16´S, 167°38´E, 21 Nov 1996, 1128– 1150 m, HALIPRO 2, stn BT 75 ; ‘photo 1-13-14-15’, coll. RV Tangaroa , ( MNHN Is.6011).

Description. Body 1.2 as long as wide, widest at coxae 3, dorsal surfaces smooth. Head anterior submarginal ‘ridge’ entire; dorsally without tubercles, posterior margin with low rounded median tubercle. Eyes present. Pereonites dorsally without tubercles. Coxae 4 extending to mid-pleonite 2; coxae 5 extending posteriorly along 0.3 of pleotelson length; coxae 6 extending to between posterior of uropods and pleotelson posterior margin, and along 0.9 of pleotelson length. Ventral coxal plates 2–4 mesially flat, plates 2–4 mesially with anterior and posterior ridges. Pleonites extending posteriorly along 0.8 pleotelson lateral margin; pleonite 1 sternal plates 3with acute median point, sternal plate 1 with median ridge and 2 sub-median depressions. Pleotelson dorsal surface with weak median longitudinal carina, with paired sublateral carinae; pleotelson lateral margins convex, pleotelson posterior margin converging to rounded caudomedial point.

Antennule flagellum 2.0 as long as peduncle articles 3 and 4, extending to pereonite 3. Antennal flagellum 1.2 as long as peduncle article 5, extending to posterior of pereonite 4.

Pereopod 2 propodus 2.5 times as long as wide, inferior margin with indistinct heel, palm straight, inferolateral margin with 6 RS, inferomesial margin with 6 RS, inferior margin RS simple, acute, smooth; dactylus 0.6 as long as propodus. Pereopod 7 similar to, but 0.8 as long as pereopod 6.

Size. Males 14.6–16.9 mm, ovigerous females 18.5 mm.

Remarks. Myopiarolis novaecaledoniae may be identified by the flat sternal coxae that have mesial ridges that do not form a clear mesial ‘X’, the lack of dorsal ornamentation, long coxae 6 that extend to near the pleotelson apex, the pleonites 2 and 3 extending along the pleon to close to the point of insertion of the uropods, and the number, arrangement and shape of the robust setae on the male pereopod 2 palm. The most similar species, also from New Caledonia, but apparently occupying a more shallow depth range, is Myopiarolis systir sp. n. Both species lack dorsal tubercles, and have long coxae 6, but M. novaecaledoniae can be distinguished from M. systir by lacking the prominent X-shaped ridges on the sternal coxae, and having the pleonites extend much further along the pleotelson. Th e numerous differences between these two species are discussed in detail under the remarks for M. systir .

One immature paratype is here re-identified as Myopiarolis sp. (p. 48, Fig.24 ). Of the non-type material identified by Poore and Brandt (1997) one is an immature female of M. systir , and the specimens from off Norfolk Island are Myopiarolis norfanz sp. n.

Examination of the type material revealed some discrepancies between the specimens and the description, here emended. Th ere are medial flanges on the mesial margin of pleopod 4 exopods, and lobes adjacent to sutures on pleopods 4 and 5; the pleotelson does have a longitudinal carina, but it is weak; pereonites 5–7 were figured as entire but are medially fused; there is a low rounded medial nodule on the posterior margin of the head; and the transverse ridge on the head is more anteriorly positioned.

Distribution. New Caledonia, 1128–1410 m.

Figures

Figure 7. Sedorolis simplex sp. n. Paratype 3 4.8 mm, Is.6001, except E, F ♀ unmeasured, Is. 6004.A–D pereopods 1, 2, 6 and 7 respectively a detail of pereopod 1 propodal palm setae E pereopod 1 dactylus F pereopod 2 propodus, mesial G pereopod propodus, lateral.

Figure 8. Sedorolis simplex sp.n. Paratype 3 4.8 mm, Is.6001. A–E pleopods 1–5 respectively F uropods.

Figure 9. Myopiarolis koro sp. n. Holotype, except F–H, female paratype. A dorsal view B lateral view C frons D pleon and pleotelson, ventral view E sternites and ventral pleonites F antenna G antennule H antenna article 2, ventral side.

Figure 10. Myopiarolis koro sp. n. Female paratype, except D, holotype. A right mandible B right mandible C left mandible D maxilliped palp E maxillule F maxilla G maxilliped H mandible palp, distal article 2 and article 3.

Figure 19. Myopiarolis novaecaledoniae. Holotype. A dorsal view B sternites and ventral pleonites C pereopod 6 carpus inferior margin setae D maxilliped E pleopod 2 endopod, detail F pereopod 2 propodus and dactylus G pleopod 4 H pleopod 5.

Figure 24. Myopiarolis sp. A dorsal view B lateral view.