Sedorolis simplex, 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 : 31-37

Sedorolis simplex sp. n.

urn:lsid:zoobank.org:act:8F2B963A-1115-46F5-A4DD-9F828AA5B921

Figs 5–8

Material

All material from New Caledonia.

Holotype: 3 (4.7 mm), 22°47.30´S, 167°14.30´E, 30 Aug 1985, 440 m, BIOCAL stn DW44 ( MNHN Is.6000) . Paratypes: 3 (4.8 mm; NLB dissect left side, mouth, P1, P2, P6, P7, Plp 1, 2, 4, 5), ♀ (ovig. ̴ 5.3 mm), same data as holotype ( MNHN Is.6001, incl. 5 microslides). 2 3 (5.3, 5.5 mm), 22°15´S, 167°150´E, 05 Sep 1985, 440 m, BIOCAL, stn. DW 77, N.O. ‘Jean Charcot’ ( MNHN Is.6002) .

Additional material: All in poor condition, some specimens heavily dissected previously and extensively mutilated: 8 (all small <5 mm; one dissected), 440 m, BIOCAL, stn. DW 44 ( MNHN Is.6003). 3 (pre-dissected), ♀ (pre-dissected), 570 m, ex BIO- CAL stn DW 46 ( MNHN Is.6004). 5 (poor condition), 570, DW 46 m ( MNHN

Is.6005). 10 (condition very poor, possibly partly decomposed), 22°15´S, 167°150´E, 05 Sep 1985, 440 m, BIOCAL, stn. DW 77, N.O. ‘Jean Charcot’ ( MNHN Is.6006). Appendages from the previously dissected 3 DW46 ( MNHN Is.6004) were not complete, missing one posterior leg, maxilliped and the maxilla ; pleopod 5 lacked one ramus, and the maxillule lacked the endite.

Description. Body 1.3 as long as wide, widest at coxae 3 and coxae 4, dorsal surfaces smooth. Head anterolateral lobes weakly convex, anterior submarginal ‘ridge’ on lateral lobes only; dorsally without tubercles, posterior margin without median tubercle. Pereonites all with visible entire sutures, articulating, pereonite 1 anterolateral margin continuously convex; dorsally without tubercles. Coxae of pereonites 2–4 articulated, with dorsal sutures (sutures weak), distal margins truncate; coxae 4 not posteriorly extended; 5 extending posteriorly along 0.3 of pleotelson length; coxae 6 extending to mid-length of uropod peduncle, and along 0.5 of pleotelson length. Ventral coxal plates 2–4 meeting midline, mesially flat, plates 2–4 mesially simple, smooth; plates 6 and 7 incompletely separated (partly fused). Sternites 5–7 visible, sternite 5 not mesially demarcated by suture. Pleonite 1 sternal plates trilobed, lobes gently rounded, sternal plate 1 without median ridge. Pleotelson 0.8 times as long as anterior width, dorsal surface with median longitudinal carina (weak), without paired sublateral carinae; lateral margins weakly sinuate, posterior margin broadly truncate, without distinct median excision.

Antennule peduncle article 2 1.6 times as long as wide; articles 3 and 4 2 times as long as article 2; article 3 4.2 times as long as wide; flagellum 1.4 as long as peduncle articles 3 and 4, with 22 articles, extending to anterior of pereonite 3. Antenna peduncle article 4 3.2 times as long as wide, 3.5 times as long as article 3; article 5 1.2 times as long as article 4, 4.3 times as long as wide; antennal flagellum 0.7 as long as peduncle article 5, with 9 articles, extending to posterior of pereonite 4.

Epistome with obtuse median point. Mandible incisor with 2 posterior cusps, left mandible lacinia mobilis 0.5 as wide as incisor, right mandible lacinia mobilis distally multicuspid, mandibular spine distally serrate; palp article 2 with 10 distolateral setae, article 3 with 19 biserrate setae. Maxilla mesial lobe with 28 long, finely serrate setae; middle lobe and lateral lobe each with 2 distal simple setae. Maxilliped palp article 2 proximomesial margin with 3 setae, distomesial margin with 7 setae, lateral margin distally with 2 setae; article 3 lateral margin with 1 setae, distal margin with 9 setae; endite distal margin RS simple.

Pereopod 1 carpus RS with prominent pilose flagellum; propodus 1.9 times as long as wide, inferior margin with ̴38 RS; narrow RS trifid, distally pilose. Pereopod 2 basis 4.5 times as long as greatest width; 0.7 times as long as basis, ischium 3.2 times as long as wide; merus 0.5 as long as ischium, 1.8 times as long as greatest width, inferior margin with 1 cluster of setae (2), superior distal angle with 1 seta (RS); carpus 0.6 as long as ischium, 1.4 times as long as wide, inferior margin with 2 clusters of setae (as 1 and 1); propodus 0.6 as long as ischium, 2.1 times as long as wide, inferior margin with indistinct heel, palm straight, inferolateral margin with 4 RS (and 3 simple setae), inferomesial margin with 3 RS, inferior margin RS distally bifid, smooth, distal margin with 6 setae, dactylus 0.5 as long as propodus, unguis offset to axis of dactylus. Pereopod 6 basis 4.0 times as long as greatest width; ischium 0.8 as long as basis, 3.5 times as long as wide, inferior margin with 1 cluster of setae (1); merus 0.7 as long as ischium, 2.8 times as long as wide, inferior margin with 3 clusters of setae (as 1, 1, and 2), superior distal angle with 3 setae; carpus 1.1 as long as ischium, 4.6 times as long as wide, inferior margin with 5 clusters of setae (as 2, 2, 2, 3 and 3), superior distal angle with 7 setae; propodus 0.8 as long as ischium, 5.8 times as long as wide, inferior margin with 3 clusters of setae (as 2, 3 and 3), distal margin with 8 setae, inferior distal angle with 2 RS; dactylus 6.0 as long as proximal width. Pereopod 7 similar to, but 0.7 as long as pereopod 6. Setae on inferior margins of pereopods 4 to 7 simple and distally flexible. Inferior margins of pereopods 2–7 setulose fringe absent.

Pleopod 1 Peduncle 3.5 times as long as wide; exopod 1.7 as long as wide, with 16 PMS; endopod 2.3 times as long as wide, 0.6 as long as exopod, with 6 PMS. Pleopod 2 peduncle 4.0 as long as wide; exopod 1.7 as long as wide, with 19 PMS; endopod 6.1 as long as greatest width, lamellar part 4.7 as long as wide, with 5 PMS; appendix masculina 2.9 times as long as endopod. Pleopod 3 exopod with 22 PMS, endopod with 12 PMS. Pleopod 4 exopod with complete transverse suture, endopod with incomplete or weak transverse suture. Pleopod 5 exopod with complete transverse suture, endopod with incomplete transverse suture.

Uropods (rami + peduncle) 0.8 as long as pleotelson, peduncle 0.6 as long as endopod. Endopod 2.3 as long as wide; distally broadly rounded. Exopod 0.6 as long as endopod, 2.3 times as long as wide, distally broadly rounded.

Size. 4.8 to 5.5 mm.

Colour: No chromatophores; pale cream–yellow.

Remarks. Th e species is identified by the characters of the genus. See Sedorolis sp. for comments on potential species character differences.

Distribution. New Caledonia, in the vicinity of the type locality; 440– 570 m.

Etymology. From the Latin simplex , simple–in the sense of smooth, not ornamented.

Figures

Figure 5. Sedorolis simplex sp. n. Holotype, except E. A dorsal view B lateral view C head, anterior margin D frons E ventral coxae 2–5 F male sternites and ventral pleonites G ventral pleonites, ♀ 5.3 mm, Is.6001 H pleotelson and uropods, ventral view I uropods, dorsal view in situ.

Figure 6. Sedorolis simplex sp. n. Paratype 3 4.8 mm, Is.6001, except C, D, ♀ ovig 5.3 mm, Is. 6001. A antenna B antennule C left mandible D right mandible E left mandible F maxillule G maxilla H maxilliped I mandible palp.

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.