Harlan K. Dean

Echiura from Antarctic and adjacent waters

Abstract A collection of 555 Echiura from the far southern seas made by American research vessels (1962–1986) yielded 9 species. An illustrated key and morphological notes are provided. Geographical ranges of these taxa are expanded, but only one (Protobonellia nikitini) is new to Antarctica. The large number of specimens allows a more complete description of certain characters, e.g., for Echiurus antarcticus. Biometric analyses showed the delayed ontogeny of gonoducts, but early appearance of anal vesicles. Previously reported Antarctic echiurans not found in this study are discussed and two putative taxa of Salvini-Plawen are considered no longer valid (E. torulobotus=E. antarcticus and Binoraphorus geminolobotus=species inquirendum). Zoogeographical analysis shows no differential distribution along horizontal gradients, but depth is important. The Echiuridae prefer sub-littoral and shallow bathyal water while the Bonelliidae are more common at bathyal and abyssal depths.

Polychaetes (Annelida: Polychaeta) of Cocos Island National Park, Pacific Costa Rica

Abstract: An extensive collecting effort resulted in identification of 106 species of polychaetes from the intertidal and shallow subtidal of Isla del Coco, Costa Rica. One hundred and three of the species reported here are new records. Only two species had not been previously collected from the Pacific coastline between Mexico and Chile. Transport of polychaetes to the island either as larvae, adults, or by rafting is discussed. Comparisons are made with the less well-analyzed polychaete fauna of the Galapágos Islands, with lower species richness on the smaller and ecologically less variable Isla del Coco. Relative lack of isolation between the polychaetes of Isla del Coco and the mainland is discussed.

Polychaetes and Echiurans

A total of 724 species of polychaetes have been reported in the primary literature from Central America with 583 from the Pacific coast and 208 from the Caribbean coast, of these 67 species were reported to occur along both coasts. A total of 317 species of polychaetes have been reported from Costa Rica, 317 from the Pacific coast, and 4 of these also from the Caribbean. There has been only a single record of a member of the problematic phylum Echiura from Central America, that from the Pacific coast of Costa Rica. The number of species of polychaetes and echiurans from Central America is lower than expected in relation to surveys from other geographic regions and this is most probably a function of lower sampling effort. H.K. Dean Museum of Comparative Zoology (MCZ), Harvard University, 26 Oxford St. Cambridge. Massachusetts. 02138. USA. e-mail: Harlandean@umb.edu Iphione ovata, a polychaete found in Pacific Costa Rica. (Photo: Arthur Anker) I.S. Wehrtmann, J. Cortés (eds.) Marine Biodiversity of Costa Rica, Central America, 181

Occurrence of the Phoronid Phoronopsis albomaculata in Cocos Island, Costa Rica

Abstract: The phoronid Phoronopsis albomaculata was collected in subtidal (28–35 m) sandy sediments in Bahía Chatham during a benthic survey designed to describe the biota of Cocos Island (Isla del Coco), Costa Rica, a national park and Human Heritage Site. Occurrence of this widespread species in Cocos Island is the first report of a phoronid for Costa Rican waters and is the second locality recorded for the eastern Pacific. Taxonomically significant characters (presence of an epidermal collar, extent of coiling of lophophore and nephridia) are discussed. Comparisons are made between depth and abundance of this species from Cocos Island and results of previous studies.

The Orbiniidae (Annelida: Polychaeta) of Pacific Costa Rica

Seven species of Orbiniidae are described from the Pacific coast of Costa Rica including two new species. Leodamas hamatus n. sp., a commonly occurring species on the coast of Pacific Costa Rica, is described from 11‒18 m in the Gulf of Nicoya and Bahia Culebra. This species is unusual in that the neuropodial uncini differ morphologically from anterior to posterior in the thorax. Scoloplos cryptospinigerus n. sp. is described from 18-22 m in the Gulf of Nicoya and has only a few short, toothed spines amidst numerous capillary setae in most of the thoracic neuropodia. This arrangement of thoracic neurosetae is unusual and has been seen only in one other described species of Scoloplos from Australia.