Rev. Biol. Trop. 49. Supl. 2: 69-84, 2001 www.rbt.ac.cr, www.ucr.ac.cr Capitellidae (Annelida: Polychaeta) from the Pacific Coast of Costa Rica Harlan K. Dean Department of Invertebrate Zoology, Museum of Comparative Zoology, 26 Oxford St., Cambridge, MA 02138 USA. E-mail: [email protected] (Received 23-XI-2000. Corrected 12-III-2001. Accepted 24-IV-2001) Abstract: Eleven species of Capitellidae (Annelida: Polychaeta) belonging to eight genera are reported from the subtidal and intertidal of the Pacific Coast of Costa Rica. Three species, Mediomastus ambiseta, M. californiensis and Notomastus hemipodus, are found in highest abundances and are widespread in subtidal and intertidal environments. A taxonomic key to these species is included. Key words: Polychaeta, Capitellidae, Costa Rica, Eastern Pacific, Tropical. The Capitellidae are a family of polychaetes stomium is variable being either well-devel- found in many sediment types, often in high oped with or without setae, only partially abundance, from the intertidal to the deep-sea. visible, or totally hidden. Immediately behind Most live in mucous-lined tubes or burrows the prostomium and/or peristomium there may (Blake 2000) and they are generally regarded be up to two achaetous segments or these may as non-selective deposit feeders. There is be lacking. The first setiger may be complete, evidence, however, that at least a few species with capillary setae in both the notopodium may exhibit some selection of food material and neuropodium, or incomplete, with capilla- (Fauchald & Jumars 1979). Many species (for ry setae present only in the notopodium. There example the Capitella capitata species com- is much variation in the number of setigers plex) are opportunistic and have been rec- bearing only capillary setae and this is the ommended in the past as indicator organisms most important character utilized in the for environmental disturbances such as pollu- differentiation of genera. The number of tion (Reish 1957, 1979; Grassle & Grassle thoracic segments is quite stable within each 1974, 1976). Pearson & Rosenberg (1978) as genus while the number of abdominal seg- well as Warren (1991) point out, however, that ments is variable. One problem in the identifi- rich abundances of such opportunists as C. cation of species is the difficulty in recogni- capitata may reflect high organic enrichment, zing the transition from the thorax to the regardless of its cause. abdomen. This transition may be quite appa- The capitellids appear outwardly similar to rent with an abrupt change in the size or mor- earthworms due to their simple morphology phology of the segments in each region. In and lack of protruding parapodial lobes. The many cases, however, the only indication of prostomium is quite simple, lacking appen- this transition between body regions is a dages and having small pigmented eyespots or changeover from capillary setae in the thoracic ocular fields only in a few species. The peri- neuropodia (and perhaps notopodia) to hooks 70 REVISTA DE BIOLOGIA TROPICAL in the abdominal region or perhaps an abrupt of Panama Monro (1933) recorded two species increase in the number of setae (capillaries or belonging to the genus Dasybranchus and hooks) in the neuropodial fascicle. The abdo- Fauchald (1973) later described a species of minal region is usually uniform throughout Notodasus from intertidal sands. Dean (1996a although some capitellids possess thin-walled & b) listed three species of capitellids collected branchial structures or have modified setae in subtidally from the Gulf of Nicoya and also far posterior segments (i.e. Mediomastus listed three subtidal species from Golfo Dulce ambi-seta (Hartman 1947), the genus in Costa Rica for a total of five separate species. Scyphoproctus Gravier). The pydidium is Vargas (1987, 1988, 1989) has sampled inten- usually not an important taxonomic character sively at an intertidal site at Punta Morales in with the genera Scyphoproctus and Pulliella the Gulf of Nicoya and reported Mediomastus Fauvel being no-table exceptions. californiensis to be one of the numerically Fauchald (1977) listed 36 genera within the dominant benthic species. This paper reviews family Capitellidae and several new genera eleven species of Capitellidae collected either have since been described (Amastigos Piltz subtidally or intertidally from the Gulf of Ni- (1977); Dodecaseta McCammon & Stull (1978); coya and Golfo Dulce on the Pacific coast of Nonatus Amaral (1980); Octocapitella Brown Costa Rica. (1987); and Paracapitella Carrasco (1987)). Ewing (1984a) estimated there to be 140 MATERIALS AND METHODS species of capitellids known to that time. Concerning the Pacific Ocean, Hartman Subtidal material was collected in the Gulf (1947) reviewed 19 species of capitellids from of Nicoya using a modified Smith-McIntyre the northeast Pacific and later reported 25 taxa bottom grab. Subtidal station sites and sediment (including 4 subspecies of Capitella capitata) characteristics may be found in Maurer & Var- from Cali-fornia (Hartman 1969). Fauchald gas (1984). Intertidal specimens were collected (1972) later recorded an additional 9 species in the Gulf of Nicoya by the author during a of capitellids from deep waters off Mexico. De series of collecting trips partially supported by León González (1994) and Hernández- the Universidad de Costa Rica’s Centro de Alcántara & Solís-Weiss (1998) reported 34 Investigación en Ciencias del Mar y Lim- known species of capitellids from the Gulf of nología (CIMAR). J. A. Vargas (CIMAR), California, Mexico, although Hernández- provided material from his study site at Punta Alcántara (1992) indicated that, despite the Morales and from the intertidal of Golfito and high number of species, the capitellids were H. Buttner (Center for Tropical Marine not particularly abundant. Further south in the Ecology (ZMT), Bremen, Germany), kindly eastern Pacific, Carrasco (1977) and Carrasco provided specimens from several mangrove & Gallardo (1987) have found five species of sites in the Gulf of Nicoya. Voucher capitellids from the Chilean coast while specimens of most of these species have been Hartmann-Schröder (1962) has reported two deposited in the Museo de Zoología, species from the Peruvian coast. Universidad de Costa Rica or the Museum of There have been few species of Capitellidae Comparative Zoology (MCZ), Harvard reported from the Pacific coast of Central University, Cam-bridge, MA, USA. America. Hartmann-Schröder (1959) reported a single species, Mediomastus setosus (proba- Key to species of Capitellidae collected from bly M. ambiseta (Warren et al. 1994)), from the Pacific coast of Costa Rica the mangroves of El Salvador. Molina-Lara & Vargas-Zamora (1995) resampled Hartmann- 1. First four thoracic setigers with capillary Schröder‘s study site about 30 years later and setae………………………………………….2 again found the species described as M. 1a. More than four thoracic setigers with capil- setosus but also found the capitellid Dasy- lary setae……………………………………..3 branchus lumbricoides Grube 1878 as one of the numerical dominants. On the Pacific coast ECOSISTEMAS ACUATICOS DE COSTA RICA II 71 2. Spinous bifid hooks in abdominal noto- 10a. Thirteen thoracic setigers with capillary podia. Capillary setae in posterior notopodia setae …………….Dasybranchus lumbricoides ………….…………….Mediomastus ambiseta 2a. Spine-like notopodial hooks and posterior Species Descriptions capillary setae absent, thoracic and abdominal hooks morphologically similar, body more Capitella capitata (Fabricius 1780). robust in appearance……………….…………. Fig. 1-3 …………………. Mediomastus californiensis Lumbricus capitata Fabricius 1780: 279. 3. Five thoracic setigers with capillary setae Capitella capitata. --Hartman 1969: 361. ……………………….Heteromastus filiformis --Maurer et al. 1988: 46. --Warren 1991: 3a. More than five thoracic setigers with capil- 276 -282. lary setae……………………………………..4 Paraheteromastides sp. --Dean 1996b: 83. 4. Thorax with 9 segments, 7 thoracic setigers Material examined: --Gulf of Nicoya, Sub- with capillary setae (when mature) tidal: Sta. 4, 9º53'40" N, 84º46'10" W, 40 m, …………... mud, Jul 1980, (1, USNM 80410). Intertidal: …………………………………Capitella capitata Jicaral, 9º58' N, 85º06' W, intertidal, man- 4a. More than nine thoracic segments ………5 grove roots, Jan 1996 (1)(coll: H. Buttner). --Golfo Dulce, Subtidal: Sta GD-09 (León- 5. Ten thoracic setigers with capillary setae, Morales & Vargas 1998), 8º39' N, 83º26' W, first setiger incomplete; with patches of pale 43 m, grey mud, Dec. 1993, (1). Intertidal: orange eyespots ….……….Decamastus nudus Golfito Bay, 8º38' N, 83º10' W, 2 Km west of 5a. More than ten thoracic setigers with capil- main dock, muddy sand, Sep 1986;(8) (coll: lary setae …………………………………….6 J.A. Vargas). 6. Eleven thoracic setigers with capillary setae Remarks: Capitella capitata is a medium- ……………………………………………….7 sized species with 9 thoracic segments and no 6a. More than 11 setigers with capillary setae visible peristomium or achaetous segments, ……………………………………………...10 thus segments 1-7 bear capillary setae only (Fig. 1). Two individuals had mixed fascicles 7. At least first two abdominal notopodia with in both the notopodia and neuropodia of mixed fascicles of both capillary setae and setigers 6 and 7. Warren (1976) found that hooks, first setiger juvenile individuals of this species may incomplete………………... exhibit mixed fascicles in anterior segments ………………………..Mastobranchus variabilis beginning as early as setiger 4. Mature males 7a. Capillary setae