Myopiarolis norfanz, 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 : 50-56

Myopiarolis norfanz sp. n.

urn:lsid:zoobank.org:act:9369B909-3B07-4350-9D19-3B9EBC872FB7

Figs 15–18

Caecoserolis novaecaledoniae Poore & Brandt, 1997: 161 (part).

Material. Holotype: 3 (10.7 mm), Lord Howe Plateau, 32°26.70´S, 161°46.95´E, 25 May 2003, 1130– 1147 m, NORFANZ stn TAN0308/77, RV Tangaroa ( NIWA 27940 ) . Paratypes: 3 3 (10.4, 10.5 [uropod], 10.7 [dissected] mm), 2 ♀ (ovig. 12.2, 13.7 mm), same data as holotype ( NIWA 27536).

Additional material. Misidentifed by Poore and Brand (1997) as M. novaecaledoniae . 3 (11.8 mm), off Norfolk Island, 29°46.6´S, 167°58.9´E, 1 Jan 1976, 500 m, coll. J. E.

Watson on Dmitri Mendeleev ( NMV J6796). 3 (11.4 mm), off Norfolk Island, 30°31.1´S, 161°54.2´E, 29 Dec 1976, 1210 m, coll. J. E. Watson on Dmitri Mendeleev ( NMV J7763)

Description. Body 1.4 as long as wide, widest at coxae 3, dorsal surfaces smooth. Head anterolateral lobes weakly convex, anterior submarginal ‘ridge’ entire; dorsally

with central small tubercle, pair of sub-lateral tubercles on posterior margin and tubercle laterally adjacent to eye; posterior margin with low rounded median tubercle. Eyes present. Pereonite 1 anterolateral margin continuously convex; dorsal surfaces posterolateral margins of pereonites 1–4 with row of small tubercles, pereonites 3 and 4 with single small tubercle at posterodistal corner. Coxae distal margins weakly convex; coxae 4 extending to mid-pleonite 1; 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 mesially elevated, plates 2–4 mesially with ridges forming

X-shape; plates 6 and 7 entirely separate. Pleonites extending posteriorly along 0.9 pleotelson lateral margin; pleonite 1 sternal plates with acute median point, sternal plate 1 without median ridge (plates 2 and 3 with median ridge). Pleotelson 1.0 times as long as anterior width; dorsal surface without median longitudinal carina, with paired sublateral carinae; lateral carinae angle of inflexion raised, thickened; lateral margins straight; posterior margin converging to rounded caudomedial point, without distinct median excision.

Antennule peduncle article 2 2.1 times as long as wide; articles 3 and 4 2.3 times as long as article 2; article 3 8.2 times as long as wide; flagellum 2.7 as long as peduncle articles 3 and 4, with ̴50 articles, extending to pereonite 4. Antenna peduncle article 4 6.3 times as long as wide, 1.9 times as long as article 3; article 5 1.2 times as long as article 4, 10.9 times as long as wide; antennal flagellum 1.9 as long as peduncle article 5, with ̴20 articles, extending to posterior of pereonite 3.

Epistome with acute median point. Mandible incisor even or minutely irregular, left mandible lacinia mobilis 0.9 as wide as incisor, right mandible lacinia mobilis distally multicuspid, mandibular spine simple; palp article 2 with 24 distolateral setae, article 3 with 26 biserrate setae. Maxilla mesial lobe with 12 long, finely serrate setae; middle lobe with 2 long simple setae; lateral lobe with 2 distal simple setae. Maxilliped palp article 2 proximomesial margin with 6 setae, distomesial margin with 12 setae, lateral margin distally with 7 setae; article 3 lateral margin with 3 setae, distal margin with 8 setae; endite distal margin RS serrate.

Pereopod 1 carpus RS simple; propodus 2.0 times as long as wide, inferior margin with ̴56 RS; wide RS with serrate margins, narrow RS distally bifid, with pilose flagellum; dactylus with acute unguis. Pereopod 2 basis 5 times as long as greatest width; 0.7 times as long as basis, ischium 3.7 times as long as wide; merus 0.5 as long as ischium, 2.1 times as long as greatest width, inferior margin with 1 cluster of setae (of 1), superior distal angle with 3 setae; carpus 0.5 as long as ischium, 2.4 times as long as wide, inferior margin with 5 clusters of setae (as 2, 1, 2, 2 and 3); propodus 0.6 as long as ischium, 2.3 times as long as wide, inferior margin with distinct heel, palm weakly concave, inferolateral margin with 3 RS, inferomesial margin with 5 RS, inferior margin RS simple, blunt, distally pilose, distal margin with 8 setae; dactylus 0.7 as long as propodus, unguis blunt, with prominent secondary unguis. Pereopod 6 basis 4.0 times as long as greatest width; ischium 0.7 as long as basis, 3.6 times as long as wide, inferior margin with 1 cluster of setae (of 1), superior distal angle with 0 RS; merus 0.5 as long as ischium, 2.4 times as long as wide, inferior margin with 3 clusters of setae (as 1, 2 and 4), superior distal angle with 1 seta; carpus 0.9 as long as ischium, 4.5 times as long as wide, inferior margin with 9 clusters of setae (as 1, 2, 2, 2, 2, 3, 4, 3, 4), superior distal angle with ̴9 setae; propodus 0.8 as long as ischium, 6.9 times as long as wide, inferior margin with 9 clusters of setae (as 1, 2, 2, 2, 2, 2, 3, 1 and 2), distal margin with 8–10 setae, inferior distal angle with 0 RS; dactylus 6.7 as long as proximal width. Pereopod 7 similar to, but 0.9 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 1.4 times as long as wide, mesial margin with 3 coupling setae; exopod 2.0 as long as wide (1.96), with 37 PMS; endopod 2.2 times as long as wide, 0.6 as long as exopod, with 19 PMS. Pleopod 2 peduncle 1.7 as long as wide, mesial margin with 2 coupling setae; exopod 1.7 as long as wide, with 40 PMS; endopod 3.1 as long as greatest width, lamellar part 3.5 as long as wide, with 14 PMS; appendix masculina 3.5 times as long as endopod. Pleopod 3 exopod with 40 PMS, endopod with 21 PMS. Pleopod 4 exopod with complete transverse suture, endopod with complete transverse suture. Pleopod 5 exopod with complete transverse suture, endopod with complete transverse suture.

Uropods (rami + peduncle) 0.3 as long as pleotelson, peduncle 0.7 as long as endopod. Endopod 2.5 as long as wide; distally broadly rounded. Exopod 0.8 as long as endopod, 2.2 times as long as wide, distally broadly rounded.

Females. Similar to males, differing only in lacking the ocular nodules, the marginal nodules on the pereonites being slightly more distinct and an obscure, low longitudinal ridge on pereonite 7.

Variation. Not detailed for the small number of specimens. Th e pattern of nodules for males and females was consistent for all specimens within each sex.

Size. Males 10.4–10.7 mm (mean = 10.6 mm), ovigerous females 12.0 and 13.7 mm.

Colour. Dull brick red in preserved specimens; fresh specimens dark slate grey with broad white bands across posterior and lateral margins of coxae; eyes white.

Remarks. Caecoserolis norfanz sp. n. can be identified by the pattern of nodules on the head and pereonites 1–4, and the pleotelson lateral carinae being thickened at the point of inflection. The most similar species are C. novaecaledoniae and C. systir sp. n., both from the New Caledonian region. Th ese species can readily be separated by the lack of small tubercles on the head and pereonites 1–4.

Distribution. East of Lord Howe Island, Lord Howe Plateau; depths of 1130– 1147 metres.

Etymology. The epithet is the name of the joint NIWA–CSIRO–IRD-Nouméa RV Tangaroa expedition to the Norfolk Ridge and Lord Howe Rise in 2003; noun in apposition.

Figures

Figure 15. Myopiarolis norfanz sp. n. Holotype except E, paratype 3 10.7 mm. A dorsal view B lateral view C head, anterior margin D sternites and ventral pleonites E pleonites, ventral view F frons G antenna H antennule.

Figure 16. Myopiarolis norfanz sp. n. Paratype 3 10.7 mm. A maxilliped B left mandible C right mandible, distal margin D mandible palp E maxillule F maxilla G robust seta distal margin of maxilliped endite.

Figure 17. Myopiarolis norfanz sp. n. Paratype 3 10.7 mm. A–D pereopods 1, 2, 6 and 7 respectively a detail of pereopod 1 propodal palm setae E pereopod 2 carpus and propodus and detail of dactylus apex F pereopod 6 carpus and propodus G pereopod 7, dactylus apex.

Figure 18 Myopiarolis norfanz sp. n. Paratype 3 10.7 mm, except G, paratype 3 10.5 mm A-E pleopods 1–5 respectively F pleopod 2 endopod detail G uropod.