Thysaneroserolis orbicula Bruce 2009, sp. n.
Creators: name: Bruce, Niel
Publisher: name: Zenodo
Year: 2009
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Isopoda
Serolidae
Thysaneroserolis
Thysaneroserolis orbicula

description: <i>Thysaneroserolis orbicula</i> sp. n. urn:lsid:zoobank.org:act: DDA89194-4F26-4B9F-9FBC-6A02B3D69AC9 Figs 25–27 <b>Material.</b> <i>Holotype:</i> &amp;female; (ovig., 7.0 mm), off Lord Howe Island, 23°51.30–31´S, 161°43.13–42.96´E, 5 Oct 2005, BBISCOL stn DW2482, 400– 430 m, manganese (MNHN Is.6024, 2 microslides). <b>Description.</b> <i>Body</i> 0.9 as long as wide (1.2 as long as overall length inclusive of antenna and uropods), widest at coxae 2, dorsal surfaces polished in appearance and irregularly nodular. <i>Head</i> anterolateral lobes straight, anterior submarginal ‘ridge’ entire; dorsally with pair of low sub-median tubercles anterior to eyes, posterior margin without median tubercle. <i>Eyes</i> minute (less than 5% greatest width of head), reniform, ommatidia not distinct (possibly absent). <i>Pereonites</i> all entire, articulating; <i>Pereonite 1</i> anterolateral margin continuously convex; dorsal surfaces without tubercles. <i>Coxae</i> of pereonites 2–4 articulated, with dorsal sutures, distal margins weakly convex; coxae 4 extending to anterior margin of pleotelson; coxae 5 extending posteriorly along 0.5 of pleotelson length; coxae 6 extending to posterior margin of pleotelson, and along 0.8 of pleotelson length. <i>Pleonites</i> extending posteriorly along 1.1 pleotelson lateral margin; pleonite 1 sternal plates with single median lobe, sternal plate 1 without median ridge. <i>Pleotelson</i> 0.8 times as long as anterior width; dorsal surface with median longitudinal carina (not reaching posterior margin), without paired sublateral carinae; lateral margins straight; posterior margin sub-truncate (with median point), without distinct median excision. <i>Antennule</i> peduncle article 2 1.1 times as long as wide; articles 3 and 4 1.1 times as long as article 2; article 3 3.8 times as long as wide; flagellum 0.6 as long as peduncle articles 3 and 4, with 2 or 3 articles, extending to posterior margin of eye. <i>Antenna</i> peduncle article 4 2.7 times as long as wide, 3.8 times as long as article 3; article 5 0.9 times as long as article 4, 3.9 times as long as wide; antennal flagellum 0.3 as long as peduncle article 5, with 1 or 2 articles, extending to posterior of pereonite 1. <i>Epistome</i> with obtuse median point. <i>Mandible incisor</i> even or minutely irregular, left mandible lacinia mobilis 0.8 as wide as incisor, right mandible lacinia mobilis distally multicuspid, mandibular spine simple or with 1 or 2 teeth; palp article 2 with 7 distolateral setae, article 3 with 13 biserrate setae. <i>Maxilla</i> mesial lobe with 8 long, finely serrate setae; middle lobe with 2 long simple setae; lateral lobe with 2 distal simple setae. <i>Maxilliped palp</i> article 2 proximomesial margin with 2 setae, distomesial margin with 6 setae, lateral margin distally with 3 setae; article 3 lateral margin with 0 setae, distal margin with 8 setae; endite distal margin RS serrate. <i>Pereopod 1</i> carpus RS simple; propodus 2.5 times as long as wide, inferior margin with ̴48 RS; narrow RS simple, deeply bifid; dactylus with unguis distally bifid. <i>Pereopod 2 basis</i> 3.8 times as long as greatest width; 0.5 times as long as basis, ischium 2.1 times as long as wide; <i>merus</i> 0.6 as long as ischium, 1.4 times as long as greatest width, inferior margin with 1 cluster of setae (of 1), superior distal angle with 0 setae; <i>carpus</i> 0.7 as long as ischium, 1.7 times as long as wide, inferior margin with 1 cluster of setae (of 1); <i>propodus</i> 0.9 as long as ischium, 3.0 times as long as wide, inferomesial margin with 2 RS; <i>dactylus</i> 0.2 as long as propodus, unguis acute, with prominent secondary unguis. <i>Pereopod 6 basis</i> 3.3 times as long as greatest width; <i>ischium</i> 0.9 as long as basis, 3.5 times as long as wide, inferior margin with 3 clusters of setae (of 1, short), superior distal angle with 0 RS; <i>merus</i> 0.5 as long as ischium, 2.5 times as long as wide, inferior margin with 1 cluster of setae (of 1), superior distal angle with 1 seta (minute); <i>carpus</i> 0.6 as long as ischium, 3 times as long as wide, inferior margin with 2 clusters of setae (1 and 1 RS), superior distal angle with 5 setae; <i>propodus</i> 0.6 as long as ischium, 3.1 times as long as wide, inferior margin with 2 clusters of setae (RS), distal margin with 3 setae (RS), inferior distal angle with 1 RS; <i>dactylus</i> 1.6 as long as proximal width. <i>Pereopod 7</i> similar to, but 0.7 as long as pereopod 6. Setae on inferior margins of pereopods 4–7 simple. Inferior margins of pereopods 2–7 setulose fringe absent. <i>Pleopod 1</i> peduncle 3 times as long as wide, mesial margin with 3 coupling setae; exopod 2.3 as long as wide, with 11 PMS; endopod 2.7 times as long as wide, 0.7 as long as exopod, with 6 PMS. <i>Pleopod 2</i> peduncle 1.5 as long as wide, mesial margin with 2 coupling setae; exopod 2.2 as long as wide, with 15 PMS; endopod 2.8 as long as greatest width. <i>Pleopod 3</i> exopod with 24 PMS, endopod with 13 PMS. <i>Pleopod 4</i> exopod with complete transverse suture, endopod without transverse suture. <i>Pleopod 5</i> exopod with complete transverse suture, endopod without transverse suture. <i>Uropods</i> (rami + peduncle) 0.7 as long as pleotelson, peduncle 0.7 as long as endopod. <i>Endopod</i> 1.8 as long as wide; distally narrowly rounded. <i>Exopod</i> 0.6 as long as endopod, 2.3 times as long as wide, distally acute. <b>Remarks.</b> The two other species in the genus, both from the western Atlantic, are abundantly different. <i>Thysanoserolis orbicula</i> can be immediately identified and separated from its congeners (and all other serolids) by the almost circular body outline (body shorter [0.9] than wide, compared to 1.4 as long as wide in <i>T. elliptica</i> and 1.2 as long as wide in <i>T. completa</i>), very flat body, conspicuously flattened and wide antennal peduncle articles that form part of the continuous body outline, the very short antennule flagellum, and geniculate antennal flagellum. <b>Distribution.</b> New Caledonia; at depths of 400–430 metres. <b>Etymology.</b> Th e epithet is derived from the Latin <i>orbis</i> meaning round.
description: Published as part of <i>Bruce, Niel, 2009, New genera and species of the marine isopod family Serolidae (Crustacea, Sphaeromatidea) from the southwestern Pacific, pp. 17-76 in ZooKeys 18 (18)</i> on pages 65-70, DOI: 10.3897/zookeys.18.96, http://zenodo.org/record/576495