PROC. BIOL. SOC. WASH. 102(3), 1989, pp. 772-792 ORBINIIDAE (ANNELIDA: POLYCHAETA) FROM MANGROVE ROOT-MATS IN BELIZE, WITH A REVISION OF PROTOARICIIN GENERA Vivianne Solis-Weiss and Kristian Fauchald Abstract. — Benthic samples taken in root-mats of Rhizophora mangle contain four species of orbiniid polychaetes including Naineris setosa, and three new taxa, Protoaricia pigmentata, new species, Pettibonella multiuncinata, new ge-nus and new species and Pararicia belizensis, new genus and new species. Recognition of the new genera lead to a preliminary phylogenetic analysis of the genera of the subfamily Protoariciinae, brief characterizations of all genera in the subfamily and the development of a key to genera of the Protoariciinae from world-wide areas. The mangrove fauna of Twin Cays, Be-lize, has been under study for several years by a team of scientists under the direction of Dr. Klaus Riitzler of the Smithsonian Institution. As part of this overall program, a study of the fauna of the root-mats of red mangroves, especially where these are cov-ered by the green alga, Caulerpa verticillata was undertaken by Brian F. Kensley and Kristian Fauchald. The ecological findings will be reported elsewhere (Kensley & Fau-chald, in preparation). This paper is the first report on the polychaetes collected during the study; several additional papers are in preparation. Members of the family Orbiniidae have been reported from sandy and muddy en-vironments world-wide. The subfamily Or-biniinae has been revised repeatedly (Day 1977, and references therein). The subfam-ily Protoariciinae has been less comprehen-sively treated. The presence of three new protoariciin taxa in material collected in Be-lize, including two that did not belong to any known genus, caused us to review the generic subdivision of the subfamily, to up-date and clarify as much as possible defi-nitions and to attempt a phylogenetic anal-ysis of the subfamily. The subfamily is here considered monophyletic; a dubious as-sumption, but without access to very much larger materials than was currently available a more detailed study is not possible. Materials and methods.— The material was collected by K. Fauchald and B. F. Kensley as part of SWAMP (Smithsonian Western Atlantic Mangrove Program), di-rected by Dr. Klaus Riitzler. The sample localities include West Bay, Twin Cays, and the mainland side of the middle islands in Blue Ground Range (Fig. 1). The habitat sampled was covered with red mangrove forest (Rhizophora mangle) varying in height from approximately 1.5 to 5 m and in den-sity from open, isolated trees to dense forest with complete canopies. The microhabitat sampled was the root-mat where this mat was covered with a mat of Caulerpa verti-cillata. Part of the study includes a series of quantitative samples taken over a two-year period from 1979-1981. The samples were taken with a 10.4 cm diameter corer to a depth of approximately 10 cm in the sub-strate. The resulting core of the peat-like root-mat was gently broken up and screened through a 0.5 mm screen and preserved im-mediately in 10% neutralized formalin to which had been added Rose Bengal. After
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