(Annelida: Polychaeta) from the Eastern Tropical Pacific Ocean

BULLETIN OF MARINE SCIENCE, 67(1): 45–53, 2000

TOMOPTERIDS (ANNELIDA: POLYCHAETA) FROM THE EASTERN TROPICAL PACIFIC OCEAN

María Ana Fernández-Álamo

ABSTRACT The distribution and composition of species of the holoplanktonic family Tomopteridae are presented. The material was taken from 579 zooplankton samples collected on 12 cruises made by the international oceanographic Program “EASTROPAC” during five of 2–3-mo periods between January–March 1967 to January–April 1968. A total of 4110 specimens were identified consisting of only one genus and eight species. Tomopteris elegans (61%) and T. planktonis (25%) were the dominant species during this period. T. euchaeta, and T. dunckeri are reported for the first time from the Pacific Ocean and, T. krampi is recorded for the first time in the southeastern region of the Pacific.

Little has been published on holoplanktonic polychaetes from the eastern tropical Pa- cific Ocean. A few scattered records from this area can be found in the works of Chamberlin (1919), Treadwell (1943), Berkeley and Berkeley (1961, 1964) and Dales (1957). Phylo- genetic relationships of the famly Tomopteridae are not clear. Tomopterids have been considered as aberrant worms with problematic relationships to other polychaetes (Støp- Bowitz, 1948, Tebble, 1960). Due to their unique morphology and uncertain affinities, Mileikovsky (1977) erected the order Tomopterimorpha and Pleijel and Dales (1991) the superfamily Tomopteroidea. In a cladistic analysis of the Polychaeta Rouse and Fauchald (1997) excluded the Tomopteridae and other pelagic taxa from their restricted analyses, because their unusual morphology is associated with the pelagic existence and their level of study would have provided spurious results in their relationships with other polychaetes. In their analyses, Tomopteridae is included in the Phyllodocida group. Most studies of tomopterids had been made on systematics and distribution, and al- most nothing is known about their biology and ecology. It is assumed that they are voracious predators, nevertheless nothing has been observed in their transparent guts (Ushakov, 1972). Pettibone (1963) also considers them as voracious predators in the plankton, and some species may at times be the dominant forms on the plankton community and must be of considerable importance as food of fishes. The eastern tropical Pacific Ocean is characterized by a very well-developed thermocline separating warm surface water from cooler subsurface water (Wyrtki, 1964). Brandhorst (1958) and Reid (1962) have shown that the divergences and convergences associated with the surface circulation result in the formation of ridges and troughs in the topography of the thermocline. These processes have a particular importance for fertilization of the surface layer and for the distribution of the standing crop of zooplankton in this region. Wyrtki (1965) has described the general surface circulation of this region. To under- stand and to predict the nature of variation in the distribution of physical and biological properties in the eastern tropical Pacific, an international oceanographic program was developed named “EASTROPAC”. Field expeditions were carried out between January 1967–April 1968, and the study area was defined as latitude 20ºN to latitude 20ºS and from the coast of the American continents westward to longitude 126ºW (Love, 1972).

45 46 BULLETIN OF MARINE SCIENCE, VOL. 67, NO. 1, 2000

MATERIALS AND METHODS

The tomopterid polychaetes were sorted from zooplankton collections obtained on 12 expeditions during the “EASTROPAC” program. The physical and biological properties, nutrient chemis- try and meteorological data from the principal participating ships in this program are found in the EASTROPAC Atlas edited by Love (1972). This Atlas listed the stations data including the latitude, longitude, depth and date of collections. Because the description of the 579 stations examined would require so many pages, the reader may contact the author for station data. Zooplankton oblique hauls were taken with nets of 0.50 and 1.0 m mouth diameter, a length of 3.5 m in a paired-frame and constructed with of Nitex nylon with mesh apertures of 0.333 and 0.555 mm, respectively. Hauls were taken between about 200 m and the surface. The zooplankton samples were preserved at sea in buffered 10% formalin seawater (Laurs, 1972). The samples were split into 50% aliquots. One set was deposited in the Smithsonian Oceanographic Sorting Center where the worms were sorted. Generally the aliquot was sorted, but some times only a subsample of the aliquot was examined. A total of 579 samples were analyzed from five periods: January–April, April–May, June–July, and August–September 1967, and January–April 1968. Figure 1A,B,C,D show the stations localization of the 12 cruises. The geographical position of these stations is reported in detail in EASTROPAC Atlas (Love, 1972).

Family Tomopteridae Grube, 1848

Tomopterids comprise polychaetes that lead a pelagic existence spending their entire life cycles in the water column. Principal adaptations to this mode of life are parapodial modification to biramous achaetous paddles with notopodia and neuropodia adapted for swimming into membranous structures named pinnules. There are never have more than two pairs of chaetigate processes which occur in the first pairs of parapodia. In the second pair, the acicula is prolonged and may extend as long as, or longer than the body. Day (1967) has considered Tomopteris as the only valid genus of this family, and this opinion is followed in this report. Tebble (1960) considers the division of Tomopteris in two sub- genera artificial and not practical.

Genus Tomopteris Eschscholtz, 1825

Tomopteris euchaeta Chun, 1887

Material Examined.—207 spec. from 97 stations ranging from the coasts of Mexico (south of Cape Corrientes, 20°N) to Peru (south of Callao, 20°S), and westward to longitude 125°W, during five 2-mo cruise periods between January 1967 and April 1968. Type locality.—Mediterranean Sea. Remarks.—Rosa (1908) found this species in the Atlantic near the Caribbean Sea. He erected the genus Enapteris based on the structure of parapodia with rectangular rami and with the pinules only in the external part of the parapodial rami. Most authors have concurred; however, Day (1967) stated that Rosa’s specimens were juvenile stages. A study of the adults showed that the pinnules were divided into an outer frilly area bearing the glands, and an inner clear area which simulates a flattened extension of the ramus. I observed this character in all specimens studied in this survey which agrees with Day’s FERNÁNDEZ-ÁLAMO: TOMOPTERIDS FROM THE EASTERN TROPICAL PACIFIC 47

Figure 1. Map of the Eastern Tropical Pacific Ocean showing where the zooplankton samples were collected. A) from January to April, 1967; B) from April to August, 1967; C) from August to September, 1967; D) from January to April, 1968. opinion. The size of these specimens ranged from 4 to 19 mm with a mean of 8.4 mm, and 12–15 pairs of parapodia. Distribution.—Mediterranean Sea (Fauvel, 1923), Atlantic (Apstein, 1900) (Rosa, 1908; Støp-Bowitz, 1948; Day, 1967; Orensanz and Ramirez, 1973, as Enapteris euchaeta), Southwest region of Indian Ocean (Day, 1967). There are very few records in the Pacific Ocean, Day (1967) pointed out that T. euchaeta has been recorded in the North Pacific as T. nisseni, but he did not indicate the source for this information. This report validates the first record of T. euchaeta in the Pacific Ocean which was identified in an unpublished thesis (Fernández-Álamo, 1983). Rozbaczylo et al. (1987) recorded one specimen as Enapteris euchaeta collected off Coquimbo, Chile. Fernández-Álamo (1992, 1996) provided the first records of it in the Gulf of California, and off the southwestern coast of Baja California, Mexico, respectively. Vicencio-Aguilar and Fernández-Álamo (1996) recorded it from the Costa Rica Dome, Central America. 48 BULLETIN OF MARINE SCIENCE, VOL. 67, NO. 1, 2000

Tomopteris nationalis Apstein, 1900

Material Examined.—191 spec. from 93 stations ranging from the coasts of Mexico (south of Cape Corrientes, 20°N ) to Ecuador (south of Gulf of Guayaquil, 11°S), and westward to longitude 125°W, during five 2-mo cruise periods between January 1967 and April 1968. Type locality.—Naples, Italy. Remarks.—The systematic position of the species seems to be unclear since most authors have identified it as T. apsteini Rosa, 1908. However, Day (1967) mentioned that it is probably synonymous with T. nationalis Apstein, 1900. Fernández-Álamo (1983) agreed with this opinion because in Rosa’s paper the name “Tomopteris apsteini nom. nov” was used to redescribe specimens from Messina, Italy. His description is nearly identical with the description of T. nationalis in the same publication. In the survey region the size of the specimens ranged from 3 to 16 mm, with a mean of 6.5 mm, and 13–20 pairs of parapodia. Distribution.—Mediterranean Sea (Malaquin and Carin, 1911, as T. apsteini); Atlantic (Apstein, 1900; Rosa, 1908; Day, 1967), (Støp-Bowitz, 1948; Tebble, 1960, as T. apsteini). Previous records in the Pacific are scarce, probably T. eura Chamberlin (1919) found off Peru could be T. nationalis. Dales (1957) recorded it in the California Current. Berkeley and Berkeley (1964), Tebble (1962), and Sun and Wu (1979) reported it as T. apsteini off the coast of Peru in the subtropical region of the North Pacific, and China Sea, respectively. Fernández-Álamo (1991) made the first record from the Gulf of California, Fernández-Álamo (1996) found it off southwestern coast of Baja California, Mexico.

Tomopteris dunckeri Rosa, 1908

Material Examined.—134 spec. from 83 stations ranging from the coasts of Mexico (south of Cape Corrientes, 20°N ) to Ecuador (north of Gulf of Guayaquil, 2°S), and westward to longitude 119°W, during five 2-mo cruise periods between January 1967 and April 1968. Type locality.—Ceylon (Sri Lanka), Indian Ocean. Remarks.—This species is very similar to T. nationalis. In fact, the only difference is that the first cirra are lost in the adults, for which reason a revision of the type material is desirable. The size of the specimens ranged from 3 to 16 mm, with a mean of 6.5 mm, and 13–20 pairs of parapodia. Distribution.—Messina, Mediterrean Sea (Caroli, 1928a); Indian Ocean (Rosa, 1908; Caroli, 1928b; Monro, 1939; Day, 1975; Fauvel, 1953); Indopacific (Dales, 1960); Atlan- tic in the southeastern region (Day, 1967). The present report validates the first records of this species from the Pacific Ocean proposed in an unpublished thesis (Fernández-Álamo, 1983).

Tomopteris nisseni Rosa, 1908

Material Examined.—Only one spec. from the cruise Washington 45 (3 August to 25 September 1967), from 11°N and 119°W. Type locality.—Atlantic, 20°S, 27°W FERNÁNDEZ-ÁLAMO: TOMOPTERIDS FROM THE EASTERN TROPICAL PACIFIC 49

Remarks.—The single specimen was in bad conditions; however, its pinnules are char- acteristic of this species. Its size was 27 mm with 23 pairs of parapodia. Distribution.—This species seems to have a very wide distribution in the Atlantic Ocean where it has been recorded by Rosa (1908), Malaquin and Carin (1911, 1922), Southern (1911), Monro (1930), Fauvel (1932), Wesenberg-Lund (1935, 1950), Treadwell (1936 as T. longisetis), Støp-Bowitz (1948); and Tebble (1960). Dales (1960, 1963) found it off the coasts of Kenya, Tanganyika, and Indonesia. However, previous records from the Pacific are scattered. Dales (1955, 1957) recorded it from off California. He thinks that T. innatans and T. idiura of Chamberlin (1919) recorded from California to Marquezas Islands and off Peru, are synonymous with T. nisseni, and Hartman (1956) thinks the same about of T. opaca of Treadwell (1928) from Galapagos and Cocos Islands. Tebble (1962) recorded it from the North Pacific in the subtropical region.

Tomopteris krampi Wesenberg-Lund, 1936

Material Examined.—Only one spec. from the cruise Rockaway 77 (20 January to 28 April 1968), from 15° and 90°W. Type locality.—West of Greenland. Remarks.—The specimen was in good preservation, and its characteristics agree with the descriptions of Wesenberg-Lund (1936), Støp-Bowitz (1948) and Tebble (1960). It measure 12 mm with 19 pairs of parapodia. Distribution.—Atlantic Ocean (Wesenberg-Lund, 1936, 1950; Støp-Bowitz, 1948; Tebble, 1960; Day, 1967). In the Pacific Ocean, Dales (1955) provided the first record of T. krampi from Monterey Bay, California. The present report validates the first records of this species proposed in an unpublished thesis (Fernández-Álamo, 1983) from the southeastern region of the Pacific Ocean in a single locality (15ºS, 94ºW) under the influence of the Current of Peru.

Tomopteris elegans Chun, 1887

Material Examined.—A total of 1909 spec. from 232 stations ranging from the coasts of Mexico (south of Cape Corrientes, 20°N ) to Peru (south of Callao, 20°S), and westward to longitude 125°W, during five 2-mo cruise periods between January 1967 and April 1968. Type locality.—Canary Islands. Remarks.—This species is widely distributed in the survey area during the five periods studied. It was the most common tomopterid representing 65% of the abundance. This result agrees with the reports of Apstein (1900) and Tebble (1960, 1962) who found it in the warmer waters of the South Atlantic and North Pacific, respectively. In the survey region the size of the spec. ranged from 1 to 5 mm with a mean of 3.1 mm, and 7–15 pairs of parapodia. Distribution.—This species has been reported from many localities in the tropical and subtropical regions of the Atlantic. Previous records from the Pacific Ocean included Izuka (1914), Ushakov (1957a), Dales (1957), Tebble (1962), among others. Fernández- Álamo (1992) provided the first record from the Gulf of California. 50 BULLETIN OF MARINE SCIENCE, VOL. 67, NO. 1, 2000

Tomopteris planktonis Apstein, 1900

Material Examined.—A total of 877 spec. from 309 stations ranging from the coasts of Mexico (south of Cape Corrientes, 20°N ) to Peru (south of Callao, 20°S), and westward to longitude 125°W, during five 2-mo cruise periods between January 1967 and April 1968. Type locality.—Atlantic Ocean between Ascension Island and Brazil. Remarks.—This species was second in abundance (25%). The size of the specimens ranged from 1 to 8 mm with a mean of 3.5 mm, and 7–17 pairs of parapodia. Day (1967) reported a size of 7 mm long with 13–18 pairs of parapodia. Distribution.—It is a cosmopolitan species widely reported throughout the world from all explored water masses, except in the Sub-Arctic Zone of the North Pacific (Tebble, 1962). Dales (1955) reported it as T. cavallii from Monterey Bay and under same name in the California Current (Dales 1957). Berkeley and Berkeley (1957) also reported it as T. cavallii, in the Alaskan Gyre, 55ºN and 140ºW. Fernández-Álamo (1991) made the first record from Gulf of California. Fernández-Álamo (1996) found it off the southwestern coast of Baja California, Mexico.

Tomopteris septentrionalis Quatrefages, 1865

Material Examined.—A total of 39 spec. from 20 stations ranging from 19°N to 15°S, and westward between longitude 98° to 119°W, during five 2-mo cruise periods between January 1967 and April 1968. Type locality.—Danish seas Remarks.—This species has been found at a few stations in the survey area, in localities where the isotherm of 15ºC was above the 100 m depth. Ekman (1953) included it as a cold water cosmopolitan species, and these records in the eastern tropical Pacific con- firm his opinion. The size of the specimens ranged from 1.5 to 9.0 mm, and 18 pairs of parapodia. Distribution.—Widely distributed in the Atlantic (Monro, 1930; Benham, 1929; Tebble, 1960), in the Antarctic sector (Ushakov, 1957b; Blankensteyn and Lana, 1986; Lana and Blankensteyn, 1987; Lana and Blankensteyn, 1989). In the Pacific Ocean, it has been widely reported by Izuka (1914), Treadwell (1943), Berkeley and Berkeley (1957, 1964), Ushakov (1955, 1957a), Dales, (1955, 1957) and Tebble (1962).

ACKNOWLEDGMENTS

I express my sincerest gratitude to F. Ferrari from the Smithsonian Oceanographic Sorting Cen- ter and A. Alvariño from the National Marine Fisheries Service, who kindly provided the material that made this report possible. Thanks to A. Fernández Iriarte for his technical assistance in the preparation of the maps of the Figure, and M. Vicencio Aguilar for her help with preparation of the manuscript. Critical reviews by D. J. Reish and two anonymous reviewers were also of great help in later improvements of the manuscript. FERNÁNDEZ-ÁLAMO: TOMOPTERIDS FROM THE EASTERN TROPICAL PACIFIC 51

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