Myopiarolis lippa, 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 : 47-50

Myopiarolis lippa sp. n.

urn:lsid:zoobank.org:act:FFD8404E-8B2B-4821-BE05-7999BE42E67A

Figs 13 , 14

Material. Holotype: 3 (14.5 mm), northern Coral Sea, between Cape York and Gulf of Papua , 11°33´S, 146°14´E, 14 Feb 1992, CIDARIS III stn 13-2, 2053– 2012 m ( MTQ W13697).

Description. Body 1.3 as long as wide, widest at coxae 3, dorsal surfaces punctate. Head anterolateral lobes weakly convex, anterior submarginal ‘ridge’ laterally incomplete; dorsally with (pair of weak submedial tubercles and weak tubercle mesial to eyes), posterior margin with low rounded median tubercle. Eyes present. Pereonite 1 anterolateral margin continuously convex; dorsal surfaces with small median tubercle on pereonites 2, 4, 6 and 7 and pleonites 1 and 2. Coxae of pereonites 2–4 distal margins truncate; coxae 4 extending to mid-pleonite 2; coxae 5 extending posteriorly along 0.3 of pleotelson length; coxae 6 extending to mid-length of uropods, and along 0.8 of pleotelson length. Ventral coxal plates 2–4 mesially elevated, with ridges forming X-shape; plates 6 and 7 entirely separate. Pleonites extending posteriorly along 0.6 pleotelson lateral margin; pleonite 1 sternal plates with acute median point, sternal plate 1 without median ridge, with process extending to posterior of sternite 2. Pleotelson as long (0.99) as anterior width; with distinct longitudinal median carina and paired sublateral carinae; lateral carinae entirely carinate, lateral margins convex; posterior margin narrowly rounded, without distinct median excision.

Antennule peduncle article 2 2.1 times as long as wide; articles 3 and 4 2.8 times as long as article 2; article 3 9.6 times as long as wide; flagellum 2.9 as long as peduncle articles 3 and 4, with ̴56 articles, extending to pereonite 6. Antenna peduncle article 4 5.9 times as long as wide, 2.9 times as long as article 3; article 5 1.2 times as long as article 4, 12.8 times as long as wide; antennal flagellum 1.2 as long as peduncle article 5, with ̴20 articles, extending to middle of pereonite 3.

Epistome with obtuse median point.

Pereopod 1 carpus RS simple; propodus 2.2 times as long as wide, inferior margin with ̴68 robust setae; dactylus with acute unguis. Pereopod 2 basis 4.5 times as long as greatest width; 0.8 times as long as basis, ischium 4.5 times as long as wide; merus 0.4 as long as ischium, inferior margin with 2 clusters of setae (as 1 and 3), superior distal angle with 4 setae; carpus 0.5 as long as ischium, 2.9 times as long as wide, inferior margin with 3 clusters of setae (as 1, 3 and 4); propodus 0.5 as long as ischium, 2.5 times as long as wide, inferior margin with indistinct heel, palm weakly concave, inferolateral margin with 6 RS, inferomesial margin with 10 RS, inferior margin RS both blunt and acute (distal 3 acute), distally pilose, distal margin with ̴9 setae; dactylus 0.7 as long as propodus, unguis simple, blunt. Pereopod 6 basis 3.9 times as long as greatest width; ischium 0.8 as long as basis, 3.2 times as long as wide, inferior margin with 0 clusters of setae, superior distal angle with 0 RS; merus 0.6 as long as ischium, 2.5 times as long as wide, inferior margin with 2 clusters of setae (as 1, 2 and 3), superior distal angle with 2 setae; carpus 0.8 as long as ischium, 4.4 times as long as wide, inferior margin with 8 clusters of setae (as 1, 3, 3, 3, 1, 3, 3 and 3), superior distal angle with

̴9 setae; propodus 0.8 as long as ischium, 7.1 times as long as wide, inferior margin with 8 clusters of setae (as 1, 2, 3, 4, 4, 3, 1 and 2), distal margin with ̴7 setae, inferior distal angle with 0 RS; dactylus 6.8 as long as proximal width. Pereopod 7 similar to, but 0.8 as long as pereopod 6. Setae on inferior margins of pereopods 4–7 finely plumose. Inferior margins of pereopods 2–7 setulose fringe weakly developed.

Pleopod 1 peduncle 1.9 times as long as wide, mesial margin with 3 coupling setae; with 42 PMS; endopod 2.2 times as long as wide, 0.6 as long as exopod, with 22 PMS. Pleopod 2 peduncle 2.2 as long as wide, mesial margin with 2 coupling setae; exopod 1.8 as long as wide, with 44 PMS; endopod 3.5 as long as greatest width, lamellar part 3.9 as long as wide, with 22 PMS; appendix masculina 3.0 times as long as endopod.

Uropods (rami + peduncle) 0.2 as long as pleotelson, peduncle 0.6 as long as endopod. Endopod 2.4 as long as wide; distally broadly rounded. Exopod 0.8 as long as endopod, 2.5 times as long as wide, distally broadly rounded.

Remarks. Myopiarolis lippa sp. n. can be identified by the presence of a distinct medial longitudinal carina and prominent long sublateral carinae on the pleotelson, small median nodules on pereonites 6 and 7 and the pleonites, and the coxae 6 not extending to the uropod peduncle. All other species in the region lack a distinct median pleotelson carina.

The most similar species, both with medially ornate coxal sternites, are M. norfanz sp. n. and M. systir sp. n. M. norfanz is at once distinguished by the nodular ornamentation of the head and of the posterior lateral margins of pereonites 1–4; M. systir appears similar in dorsal view, but is not dorsally punctate, lacks the median pereonal and pleonal tubercles and has far longer coxae on pereonite 6.

Dissection and therefore description was minimised in order to conserve the physical integrity of the holotype. The antennae and uropods were described in situ, and of the mouthparts only the maxilliped was dissected; pleopods within the genus are rather uniform and only pleopods 1 and 2 were dissected and described.

Distribution. Northern Coral Sea, depth of 2012–2053 metres.

Etymology. The epithet is a Latin word meaning ‘dim-sighted, nearly blind’ ( Brown 1956), alluding to the small eyes.

Figures

Figure 13. Myopiarolis lippa sp. n. Holotype. A dorsal view B lateral view C head, anterior margin D pleon and pleotelson, dorsal view E sternites and pleonites, ventral view F frons G antennule and antenna (in situ) H uropod(in situ).

Figure 14. Myopiarolis lippa sp. n. Holotype. A–D pereopods 1, 2, 6 and 7 respectively E detail of propodal palm setae F pereopod 2 propodus G pereopod 6 distal articles H pleopod 1 I pleopod 2.