New genera and species of the marine isopod family Serolidae (Crustacea, Sphaeromatidea) from the southwestern Pacific Author Bruce, Niel Museum of Tropical Queensland, Townsville, Queensland, Australia text ZooKeys 2009 2009-08-26 18 18 17 76 journal article 22617 10.3897/zookeys.18.96 1b25d91d-c28e-48fa-aee7-f7a9d26c61cd 1313–2970 576495 87B9757A-986D-4CCC-8276-146A617FC905 Caecoserolis Wägele, 1994 Caecoserolis Wägele, 1994: 10 (not Caecoserolis of Poore and Brandt 1997: 161 ; = Myopiarolis gen. n. ) Type species. Serolis brinki Kensley, 1978 ; original designation ( Wägele 1994 ). Description . Head lateral lobe mesial margin with single concavity; anterolateral lobes forming of continuous margin with pereonite 1; anterior submarginal ‘ridge’ absent; posterior margin without ornamentation. Eyes absent. Pereonites all entire, articulating; pereonite 1 anterior margin not strongly bent dorsally, dorsally without tubercles. Coxae of pereonites 2–4 articulated, with dorsal sutures; 2–4 and pereonite 6 entirely lacking coxal keys; distal margin truncate; coxae 6 wide, laterally or distally broad, extending proximal to insertion of uropod peduncle. Ventral coxal plates 2–4 meeting midline; simple, smooth; plates 6 and 7 entirely separate. Pleonites distally narrow or acute, laterally overlapped by coxae 6, extending posteriorly along pleotelson. Sternites 5–7 visible, fused. Sternal plates of pleonites 1–3 3-cornered, with acute median point, without median ridge. Pleotelson dorsal surface not vaulted, with weak median longitudinal carina, without paired sublateral carinae; pleotelson posterior margin evenly rounded, without distinct exit channel. Antennule flagellum 1.2–2.0 as long as peduncle articles 3 and 4, extending to pereonite 2. Antenna peduncle articles 4 and 5 broad, article 5 less than 5 times as long as greatest width; flagellum three-quarters as long as peduncle article 5. Epistome evenly rounded. Mandible incisor with two posterior cusps; left mandible lacinia mobilis three-quarters as wide as incisor or larger, right lacinia mobilis distally multicuspid; mandibular spine distally serrate. Maxilliped palp with 3 articles; article 3 cordiform, longer than wide. Pereopod 1 carpus RS–state not known (pilose vs serrate); propodal palm setae all RS, alternating straight and flattened, wide RS finely pilose, narrow RS distally bifid, with simple flagellum. Pereopod 2 propodus inferior margin without heel; palm straight; unguis simple, blunt. Penial openings narrowly separated. Pleopods 1–3 peduncles subquadrate. slightly narrower distally, pleopods 1–3 peduncles with coupling setae. Pleopod 2 endopod lamellar part slightly shorter than ramus. Uropods Biramous, inserted on pleotelson mid-laterally, positioned laterally, not forming part of continuous body outline; less than one-third as long as pleotelson, endopod distally rounded. Remarks . Caecoserolis belongs with the group of genera characterised by having a distal stem on pleopod 2 endopod, approximating to the ‘Group B’ of Wägele (1994) . The genus can be identified by the flat (or weakly domed) pleotelson that lacks lateral carinae, antenna with broad peduncular articles 4 and 5, pleopod peduncles that are sub-quadrate (slightly narrower distally than proximally) and by the short uropods inserted mid-laterally on the pleotelson; another less precise character is that Caecoserolis has a flatter body than related genera. All but the type species of Caecoserolis have been transferred to the Myopiarolis gen. n. Th e characters that most readily separate these two genera (in parentheses for Myopiarolis ) include antenna peduncle articles 4 and 5 broad with article 5 less than 5 times as long as greatest width (slender, elongate, 4.6–6.3 and 8.6–10.3 as long as wide respectively), pleopods 1–3 peduncles quadrate or subquadrate (triangular), pereonite 1 anterior margin anterior margin weakly indented (distinctly indented), pereonites all with visible entire sutures (pereonites 5–7 sutures medially fused), simple and flat pleotelson that lacks sub-lateral carina (pleotelson vaulted, with sub-lateral carinae), coxae 6 not extending posteriorly to pleonites (extending posteriorly to pleonites) and penial openings narrowly separated (fused in all species of Myopiarolis ). Distribution . The genus is monotypic, with one western Indian Ocean species, off the Natal coast of South Africa .