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Dissertations, Theses, and Masters Projects Theses, Dissertations, & Master Projects
1974
Hydroids of the Pelagic Sargassum Community of the Gulf Stream and Sargasso Sea
David Holland Rackley College of William and Mary - Virginia Institute of Marine Science
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Recommended Citation Rackley, David Holland, "Hydroids of the Pelagic Sargassum Community of the Gulf Stream and Sargasso Sea" (1974). Dissertations, Theses, and Masters Projects. Paper 1539617456. https://dx.doi.org/doi:10.25773/v5-waa7-4e36
This Thesis is brought to you for free and open access by the Theses, Dissertations, & Master Projects at W&M ScholarWorks. It has been accepted for inclusion in Dissertations, Theses, and Masters Projects by an authorized administrator of W&M ScholarWorks. For more information, please contact [email protected]. HYDROIDS OF THE PELAGIC SARGASSUM COMMUNITY OF THE
GULF STREAM AND SARGASSO SEA
A Thesis
Presented to
The Faculty of the School of Marine Science
The College of William and Mary in Virginia
In Partial Fulfillment
of the Requirements for the Degree of
Master of Arts
by
David Rackley * 1974 APPROVAL SHEET
This thesis is submitted in partial fulfillment
the requirement for the degree of
Master of Arts in Marine Science
\A ______David Holland Rackley
Approved, July 1974
Donald F./Boesch, Ph.D
\QaJU CaJLJm . Dale R. Calder, Ph.D.
C-Jci— ^ Frederick Y. Kazama, Ph.D
Franklyn D/
Marvin L. Wass, Ph.D TABLE OF CONTENTS
Page
ACKNOWLEDGMENTS ...... iv
LIST OF TABLES ...... v
LIST OF FIGURES. . vi
ABSTRACT ...... ix
INTRODUCTION...... 2
METHODS AND MATERIALS...... 6
RESULTS AND DISCUSSION ...... 11
Key...... 11
Systematic Account...... 14
APPENDIX ...... 62
FIGURES...... 76
LITERATURE CITED ...... 86
VITA ...... 94 AC KNOWLEDGMENTS
I wish to express my appreciation to Dr. Dale R.
Calder and Dr. Donald F. Boesch, under whose guidance this investigation was conducted, for their patience and criticism. I am also indebted to Dr. Victor G. Burrell,
Jr. for his aid in the collection of samples, Dr. Harold
J. Humm for his aid in the identification of Sargassum,
Mr. Robert J. Diaz for his aid in statistical analysis and to Mrs. Linda Jenkins and Miss Melissa Forrest for typing the manuscript. Special thanks is extended to
Mr. James P. Amon and to my wife, Mary, for their continuous moral support. LIST OF TABLES
Table Page
1. Hydroid species represented in these Sargassum collections ...... 9
2 . The dominant hydroid species and their relative frequency for each Sargassum form collected. 58-59
v LIST OF FIGURES
Figure Page
A. Station locations for pelagic Sargassum collections ......
1. Rhizogeton fusiformis ...... 76
2. Cladocorvne pelagica ...... 76
3. C. pelacrica...... 76
4. Coryne sp...... 76
5. Zanclea costata ...... 76
6. Garveia humilis ...... 76
7. Pennaria disticha ...... 77
8. Halecium nanum...... 77
9. Halecium nanum...... 77
10. Halecium sp. A...... * ...... 77
11. Halecium sp. A...... 77
12. Halecium sp. B ...... 77
13. Halecium sp. B...... 77 14. Clytia cylindrica ...... 78 15. Clytia cylindrica ...... 16. Clytia fragilis ......
17. Clvtia hemisphaerica...... 78
18. Clytia hemisphaerica...... 78
19. Clytia noliformis ...... 78 List of Figures (continued),*.
Figure Page
20. Clytia noliformis...... 78
21. Clytia noliformis ...... 79
22. Campanularia sargassicola ...... 79
23. Campanularia sargassicola ...... 79
24. Qbelia hyalina...... 79
25. Obelia hyalina...... 79
26. Cuspidella humilis...... 79
27. Scandia mutabilis ...... 80
28. Dynamena mayeri ...... 80
29. Dynamena quadridentata. . 80
30. Sertularia inf lata...... 81
31. Sertularia inf lata...... 81
32. Sertularia stookeyi ...... 81
33. Sertularia stookeyi ...... 81
34. Sertularia parvula...... 81
35. Antennella secundaria ...... 82
36. Antennella secundaria ...... 82
37. Halopteris diaphana ...... 82
Halopteris diaphana ...... 82
39. Plumularia margaretta ...... 83
40. Plumularia margaretta ...... 83
41. Plumularia strictocarpa ...... 83
v i i List of Figures (continued).
Figure Page
42. Plumularia strictocarpa ...... 84
43. Plumularia strictocarpa ...... 84
44. Plumularia sp...... 85
45. Plumularia s p ...... 85
46. Aglaophenia latecarinata...... 84
47. Aglaophenia latecarinata...... 84
48. Aglaophenia latecarinata...... 84 ABSTRACT
Pelagic Sargassum was collected during late spring, ■>. early summer, late summer, and late winter from stations in the Gulf Stream and Sargasso Sea. Collections were analyzed for the presence of hydrozoan polyps, hydroid affinity for particular Sargassum, their microhabitat distribution on the Sargassum, and their relative abundance. A total of 29 hy droid species was found, including 3 species not previously recorded from Sargassum. Three additional species are ap parently new. Detailed descriptions, illustrations, recent taxonomic nomenclature, and a key to the species found during this investigation are provided.
i x HYDROIDS OF THE PELAGIC SARGASSUM COMMUNITY OF THE
GULF STREAM AND SARGASSO SEA INTRODUCTION
North American Atlantic hydroids have received almost continuous study since Stimpson's (1854) synopsis of the invertebrates of Grand Manan Island, New Brunswick (Fraser,
1944). This has been the result of a relatively small num ber of scientist, yet despite their extensive contributions, the hydroid fauna of many areas or particular habitats remains poorly known. Such a habitat is the pelagic Sargassum com munity of the Gulf Stream and Sargasso Sea of the North At lantic.
Burkenroad (in Parr, 19 39) presented the only detailed study involving the hydroids associated with Sargassum. In it he identified sixteen hydroids from pelagic Sargassum in the Gulf Stream, Sargasso Sea, and Gulf of Mexico. Hydroid dominance and specificity were also determined for the differ ent Sargassum species or types distinguished by Parr (1939).
Burkenroad observed that Clytia noliformis (McCrady) is the usual dominant associated with the narrow leafed Sargassum nataris (L.) Meyen types I, II, and IX; another dominant hydroid,
Aglaophenia latecarinata Allman, is usually associated with the broader leafed Sargassum fluitans type III and natans type VIII. Burkenroad also noted that the hydroid fauna
Sargassum v. Winge (tentitively identified as the benthic
2 alga Sargassum ramifolium) was dominated by either Clava sp.
Gmelin (RhizOgeton fusiformis ? Agassiz) or Syncoryne sp.
Ehrenberg. Other dominants occasionally appeared such as
Sertularia mayeri Nutting on S. natans IX, or Sertularia flowersi Nutting on S^. natans IX and -S_. natans II. The other broad leafed form, Sargassum fluitans VIII was reported on occasion to be overgrown with S. flowersi, 53. mayeri,
S_. inflata Versluys, S. turbinata Lamouroux, Dynamena quad- ridentata Ellis and Solander or Plumularia margaretta (Nutting).
Morris and Megelberg (1973) compiled a checklist, with descriptions and illustrations, of 43 hydroids which have been reported from Sargassum. Fraser*s (1912, 1944) publica tions were the principal sources used for their checklist, and unfortunately most of the taxonomic changes put forth since those publications are not included. Also not included were the improved illustrations of many tropical hydroids since Fraser's monographs, such as those by Vervoort (1968) and Van Gemerden-Hoogeveen (1965) from the Caribbean, which have greatly facilitated hydroid identification. Furthermore, only brief remarks are given by Morris and Mogelberg concern ing hydroid occurrence on specific Sargassum species.
Bennitt (1922) surveyed the hydroids of Bermuda, report ing 18 species from Sargassum, but like Fraser, did not dis cuss the Sargassum types from which the hydroids were found.
Also at this time, Hentschel (1922) studied the epifauna of
Sargassum, which included several hydroids. He estimated specificity based on the number of polyps found on Sargassum 4
thali 10 cm long and noted that there was always a dominant
species (usually Aglaophenia on S. fluitans Bbrgesen and
Clytia on £3. natans) .
Hentschel also mentioned succession among the attached
forms in which the growing apexes of the Sargassum are colon
ized first by hydroids followed by the bryozoan Membranipora
Ctuberculata (Bush);?] which establish on the older portions
of the alga. Ryland (19 74) made similar observations on
S. natans and attributed such behavior to the presence of
tannins in the apical portions of the stems (Conover and
Sieburth, 19 64; Sieburth and Conover, 1965) which inhibit
the establishment of surface microfauna necessary for the
settlement of larger epibionts.
Wingess (19 23) study of the Sargasso Sea made during
the Danish Oceanographical Expedition of 1908-1910 served as
a basis for Parr's (19 39) separation of the Pelagic Sargassum
types and provided excellent illustrations of the Sargassum
types found. As with Kentschel and Burkenroad, Winge also noted the dominance of Clytia noliformis on 53. natans and
and Aglaophenia latecarinata on 53. fluitans.
Recently, Weiss (1968) reported six hydroid species on
Sargassum from the Gulf Stream. Species preference was briefly noted with Aglaophenia (latecarinata?) reported the dominant species on S_. fluitans with lesser quantities of
Clytia, Plumularia, Obelia, Monotheca (Plumularia) and
Sertularia. On S. natans, only Clytia (noliformis?) was 5
reported.
Finally, Defenbaugh and Hopkins (1973) listed 13 species of hydroids common to, or exclusively found on Sargassum in the Galveston Bay, Texas area.
The purpose of this study is to provide updated de scriptions, illustrations and a key for the hydroids of pelagic Sargassum from the North Atlantic and to describe some of the ecological relationships between hydroids and pelagic Sargassum types in this area. METHODS AND MATERIALS
Pelagic Sargassum was collected on the western North
Atlantic Ocean during late winter, mid and late spring, and late summer. Twenty-three late winter samples (2,600 ml) were taken from the R/V DOLPHIN by a 1 x 2 m Boothbay neuston net (0.947 mm mesh) between 13 February 19 73 and
21 March 1973 on a north-south transect of the Gulf Stream and Sargasso Sea between South Port, North Carolina (33°00'N
78°00’W) and Jacksonville, Florida (29°01'N 80°01*W). Each sample consisted of a 10 minute tow at 5 knots. Six mid and late spring samples (1490 ml) were dip netted on 29 April
1967 and 25-26 May 1969 aboard the R/V EASTWARD south of Cape
Lookout, North Carolina, on an east-west transect across the
Gulf Stream (34°16'N 75°48'W to 33°15,N 71°01,W). These samples were among those of which Fine (19 69) described the noncolonial macrofauna. Three late summer samples (850 ml) were dip netted north of Cape Hatteras (40°09fN 70°56,W) aboard the R/V EASTWARD on 1 October 1967. Figure A shows the location of the stations.
Sargassum raft volumes were quantified by water displace ment, and samples were stored in 10% buffered formalin. Hydroids isolated during the study were preserved in 70% ethanol.
Hydroids were initially identified and quantified using a dissecting microscope. Detailed examinations were made with
6
FIGURE A. Station locations for pelagic Sargassum collections
o represents late summer (October) stations
x represents mid-late spring (April-May) station
(Fine, 1970)
+ represents mid-late spring (April-May) stations
(Fine, 1970)
e represents late winter (February-March stations
7 45 ° 0 0 ’
40°00
A3
35 ° 0 0 ’
D2j Vs W7 cfe 04 D 5 W 3 W 4 W5 jW6 W1 V2 W 9 W10 30°00 W?4 W*2 *W11 W1§ W16W13 *W49—•—I W18 W17-- :-- «W^2 W20 . 1 W ? 1 TW23
■25°00
70° 0 0 ’ 8
TABLE 1. Hydroid species represented in these Sargassum
collections.
Phylum Cnidaria Class Hydrozoa Order Athecata (Gymnoblastea) Suborder Capitata Family Pennariidae Pennaria disticha Family Corynidae Coryne sp. Family Cladocorynidae Cladocoryne pelagica Family Zancleidae Zanclea costata Family Clavidae Rhizogeton fusiformis Suborder Filifera Family Bouganvilliidae Garveia humilis Order Thecata (Calyptoblastea) Family Haleciidae Halecium nanum Halecium sp. A Halecium sp. B Family Campanulariidae Clytia cylindrica Clytia fragilis Clytia gracilie Clytia hemisphaerica Clytia noliformis Campanularia sargassicola Obelia hyalina Incertae sedis Cuspidella humilis Family Hebellidae Scandia mutabilis Family Sertulariidae Dynamena mayeri Dynamena quadridentata Sertularia inflata Sertularia stookeyi Sertularella parvula Family Plumulariidae subfamily Halopterinae Antennella secundaria Halopteris diaphana subfamily Plumulariinae Plumularia margaretta Plumularia strictocarpa Plumularia sp. Subfamily Aglaopheniinae Aglaophenia latecarinata 9 a compound microscope using depression slides to prevent distortion. Laboratory grade creosote was used as a clearing agent on the thecate hydroids when necessary. Drawings were made with the aid of a camera lucida.
Patterns of occurrence of hydroid species on the various Sargassum forms were studied by numerically classifi cation. Coefficients of similarity were computed between all hydroid species which were found on any particular
Sargassum form at least three times:
S = 2c/(a+b)
where a = number of Sargassum forms occupied by
species A
b = number of Sargassum forms occupied by
species B
c = number of Sargassum forms on which both
species occurred.
The resulting between-species similarity matrix was subjected to cluster analysis using flexible sorting with 3 = -0.25
(Williams, 1971).
For this report the following definitions and limitations have been used:
1. Eupelagic Sargassum - refers to those Sargassum
species which spend their entire life cycle in the
pelagic state. This includes S. natans and S. fluitans
types.
2. Benthic Sargassum - refers to those species which,
although included in the pelagic Sargassum complex, are actually benthic forms which have been detached from the bottom.
Sargassum "types” refer to the eupelagic species as separated by Parr (1939), based on different morphological features. Sargassum "forms" may refer to any morphological group.
Synonymies are limited only to those hydroid species specifically reported from Sargassum.
Descriptions are based on Sargassum-borne hydroids from this study only.
"Known Range" refers to the Western Atlantic,
Caribbean Sea, and Gulf of Mexico only. RESULTS AND DISCUSSION
Dates and locations of collections, Sargassum forms and hydroid species encountered, the displacement volume of the Sargassum sample, the relative abundance of hydroid species and the occurrence of reproductive structures are provided in Appendix I.
Taxonomic Account
Key to hydroids of Pelagic Sargassum of the Gulf Stream
and Sargasso Sea of the Western North Atlantic
1. Hydrotheca absent...... (2) Hydrotheca present...... (7)
2. Hydranth with capitate tentacles....*...... (3) Hydranth with filiform tentacles only...... (6)
3. Hydranth with filiform and capitate tentacles, filiform tentacles well developed, more than four in number, capitate tentacles in several distal whorls Pennaria disticha Hydranth with capitate tentacles only...... (4)
4. Pedicel longer than hydranth, hydranth clavate, tentacles 10-20, scattered over entire hydranth . .’Coryne -sp. Hydranth longer than stem...... (5)
5. Capitate tentacles short, scattered over hydranth...... Zanclea costata Tentacles much longer, each having 10-15 small capitate tentacles on the primary ones. . CladOcoryne pelagica
6. Pedicel long, hydrotheca lacking, tentacles long, arranged in a distal whorl...... Garveia humilis Tentacles scattered, hydranth clavate...... _-RhiaogetQ.n fusiformis
11 12
7. Hydrotheca free from stem, supported on a pedicel...... (8) Hydrotheca adnate on stem...... (19)
8. Hydrotheca saucer shaped, not capable of covering hydranth...... (9) Hydrotheca capable of covering hydranth...... (11)
9. Pedicels rising singly from the stolon, about 0.35 mm long, margin strongly flared...... Halecium sp. B Margin slightly flared...... (10)
10. Stems long, slender, regularly branched, gonosome with 4 ova, about 5 mm long....Halecium sp. A Stems irregularly branched, gonosome with 2 ova ...... Halecium nanum
11. Hydrotheca urn shaped, hydrotheca walls corrugated, pedicel usually shorter than hydrotheca...... Sertularella parvula Hydrotheca campanulate...... (12)
12. Margin flared rim, pedicel about same length as hydrotheca, with spiral annulations, about 1 mm in length....Scandia mutabilis Margin without flaring rim, colonies longer, pedicel with straight or wavy annulations...... (13)
13. Margin entire, stem branched, hydrotheca about as deep as wide ...... Obelia hyalina Margin with teeth, branching not common...... (14)
14. Margin with acute teeth...... (15) Margin with blunt or rounded teeth...... (18)
15. Margin with 10-12 teeth, hydrotheca much longer than wide, distinct constriction at diaphram...... Clytia cylindrica Hydrotheca slightly longer than wide, constriction at diaphram slight or lacking...... (16)
16. Teeth 10-14, fine lined projected downward from apex of each tooth...... Clytia fragilia Fine lines inconspicuous or lacking...... (17)
17. Teeth 12-14, sharp or slightly rounded, pedicel rarely branched...Clytia hemisphaerica Teeth 10-14, deeply cut, sharp, pedicel irregularly branched...... Clytia gracilis
18. Margin with 10-12 low rounded teeth, separated by shallow incisions -...Clytia noliformis f LIBRARY of ihs 15 VIRGINIA INSTITUTE
MARINE SCIENCE Margin with 12 low, rounded teeth, sides of teeth parallel, 2 distinct annulations below hydrotheca...Campanularia sargassicola
19. Hydrotheca sessile, tubular, singly rising from the stolon, minute (20 7-24 6]i long) Cuspidella humilis Hydrotheca not as above...... (20)
20 . Stem and branches without nematophores, hydrotheca margin toothed, operculum present...... (21) Nematophores on stem or branches or both...... (24)
21. Hydrothecae in two longitudinal rows, one pair of hydrothecae to each internode...... (22) Hydrothecae arranged in groups or pairs in each internode...... Dynamena quadridentata
22. Mature colony with alternate branches Sertularia inf lata Mature colony unbranched...... (23)
23. Margin with 3 teeth, free part of adcauline wall short, projected upward...... Dynamena mayeri Margin with 2 teeth, free part of adcauline wall long, parallel to hydrorhiza...... Sertularia stookeyi
24. Hydrocladia arising singly from a stolon, nematophore above hydrotheca very small...... Antenella secundaria Hydrocladia attached to a hydrocaulus...... (25)
25. Hydrothecal margin with 9 teeth, intrathecal ridge extending across hydrotheca, cavity appears to be divided into two chambers ...... Aglaophenia latecarinata Hydrothecal margin without teeth...... (26)
26. Hydrocladium with one thecate and one athecate internode. .-....■...... Plumularia margaretta Hydrocladium with more than one thecate and athecate internode...... (27)
T-27. Hydrocaulus with cauline hydrotheca at each node...... Halopteris diaphana Cauline hydrothecae lacking, all nodes transverse...... (28) 14
28. Apophyses supporting hydrocladia long, distinct, axillary nematotheca 1-3, trumpet shaped...... Plumularia sp. Aopohyses less distinct, 1-2 small auxiliary nematotheca. ....Plumularia strictocarpa
Systematic Account
Order Athecata (Gymnoblastea) Suborder Capitata Family Pennariidae
Pennaria disticha Goldfuss, 1820 Plate II, Figure 7
Pennaria disticha Goldfuss, 1820, p.89.
Sargassum substrate: S. pteropleuron
Description: Colonies to 1 cm high, stem monosiphonic, dark brown on older portions to horn colored or white on side branches. Main stem with large basal annualtions, side branches alternately arranged, annulated throughout or at ends with mesial region smooth or wavy. Hydranths terminal, clavate, with a basal whorl of about 13 long filiform tentacles with slightly swollen tips, capitate tentacles short, in 2 or
3 whorls on hydranth distal to filiform tentacles.
Medusa buds immature, oval, borne on hydranth on short pedicels above filiform tentacles.
Remarks: Brinkman-Voss (19 68) gives the following account for
Pennaria disticha:
The genus Pennaria was established by Oken (1815) for several thecate hydroids, known today as Plumularia, Aglasphenia a.s.o. Goldfuss (1820) placed his P. disticha in the genus Pennaria Oken because its colonial structure was similar to the above mentioned thecate hydroids. The separation between thecate and athecate hydroids was not recognized that time. Allman (1871-72) established the genus Halocordyle for the species Halocordyle tiarella (Ayres) of the Atlantic Coast 15 of North America, This species is cogeneric with Pennaria disticha. Stechow (1923, p.47) argued that Allman's genus Halocordyle with the type species Halocordyle tiarella is held to be valid, because the name Pennaria was originally chosen by Oken for a genus whose species are nowadays named Hydrallmannia falcata, Plumularia setacea, Schizotricha frutescens, Lytocarpa myriophy1lum and Algaophenia pluma. One can emphasize as well that Goldfuss placed his P. disticha in one established genus, Pennaria, and I favour this approach. All the species except Pennaria disticha Goldfuss have been, in the course of time, removed from the genus Pennaria Oken and Pennaria disticha is left as the type species. Kramp (1959, 1961) follows this line too, maintaining Pennaria as the valid genus with P. disticha Goldfuss as type species.
Three relatively small colonies were isolated, not previously reported from Sargassum.
Known Range: Woods Hole, Bermuda, Florida Keys, Caribbean Sea.
Family Corynidae
Coryne sp. Plate I, Figure 4
Syncoryne mirabilis Fraser, 1912: p. 346, 347, fig. 3; Morris and Mogelberg, 1973: p. 10, fig. 2. Syncoryne sp. Burkenroad, 19 39: p. 23.
Sargassum substrates: S_. natans I, S. polycertium, S_* ptero pleuron, 13. f ilipendula.
Description: Colonies about 3 mm in length, stems generally
. i. unbranched or with small irregular branches, perisarc smooth or slightly wrinkled. Hydranth clavate, about same length as pedicel, tentacles short, strongly capitate, about 25 in number, scattered over hydranth.
Gonophores borne on short pedicels scattered among tentacles. 16
Measurements (in microns):
hydranth, length 69 0-9 85
pedicel, diameter at hydranth base 118-197
Remarks: Fraser (1912) reported Syncoryne mirabilis from
Sargassum washed ashore in late summer at Beaufort, North
Carolina. Russell (1953), however, described Sarsia tubulosa
(M. Sars, 1835) (=Syncoryne mirabilis Agassiz, 1862) as being a circumpolar neritic species. Calder (19 71) observed the hydroid of S_. tubulosa in Chesapeake Bay from late November through mid-May and the medusa from December through April.
The apparent boreal nature of Sarsia tubulosa suggests that reports of this species from tropical waters are questionable.
Brinckmann-Voss (19 68) points out that Syncoryne is no longer a valid genus since it is actually the hydroid phase of the medusa Sarsia, which has priority. However, Brinckmann-
Voss has further divided the Mediterranean Corynidae to in clude the genera Coryne (corynid hydroids with sporosacs) an(^ Sarsia (corynid hydroids with free medusae) . Because of the apparently boreal nature of Sarsia and the presence of what appears sporosacs rather than medusa buds on these specimens, they have temporarily assigned to the genus Coryne.
Fairly common Sargassum, found once on S. natans and once each on three benthic forms.
Known Range: Uncertain. 17
Family Cladocorynidae
Cladocoryne pelagica Allman, 1876 Plate I, Figures 2,3
Cladocoryne pelagica Allman, 1876: p. 255; Fraser, 1955: p. 108, pi. 18, fig. 80; Morris and Mogelberg, 1973: p. 9, fig. 1. Cladocoryne floccosa var. Sargassensis Hargitt, 1909: p.369. Cladocoryne sargassensis Kingley, 1910: p. 19.
Sargassum substrates: S_. hystrix, S. polyceratium.
Description: Colonies 3-6 mm in length, unbranched, growing from a smooth or slightly undulating stolon; pedicel about
4-5 times longer than hydranth, usually with about 4 deep annulations basally. Hydranth with about 6 oral capitate tentacles and about 3 irregular circlets of coryniform tentacles, each having 4 tentacles per row. Coryniform tentacles with a terminal cap of nematocysts and three longi tudinal rows of small capitate tentacles arranged principally on outer sides of main support tentacles. Larger colonies gqlden brown in color.
Gonophores scattered among coryniform tentacles, borne on short pedicels. Individual hydranths with as many as 5 gonophores present.
Remarks: Fraser (194 4) provided an adequate description of
Cladocoryne pelagica, but the specimen he illustrated apparently had all of the tentacles in a vertical position, enclosing the hydranth. Thus, the hydranth appears to have many scattered small, bifid capitate tentacles. This illustration led Morris and Mogelberg (19 73) to suppose that the tentacles of C. pelagica were branched and capitate rather than coryniform. 18
Found on the protected areas (stem and bladders) of
S. hystrix and S^. polycertium where it was abundant for such
a large hydroid.
Known Range: New England.
Family Zancleidae
Zanclea costata Gegenbaur, 1856 Plate I, Figure 5
Zanclea costata Genenbaur, 1856: p. 229; Fraser, 1944: p.43, pi. 3, fig. 11; Fraser, 194 7: p. 3; Defenbaugh and Hopkins, 19 73: p. 47, 48, pi. 1, fig. 5; Morris and Mogelberg, 19 73: p. 10, fig. 3. Zanclea gemmosa Fraser, 1944: p. 43, 44, pi. 3, fig. 12; Morris and Mogelberg, 19 73: p. 11, fig. 4. Corynitis agassizii Murbach, 1899: p. 354. Gemmaria costata Fraser, 1912: p. 346, fig. 2; Wing£, 1923: p. 13; Germain, 1935: p. 13; Fraser, 1943: p. 86; Adams, 19 60: p. 81. Gemmaria sp. Timmermann, 19 32: p. 296; Burkenroad, 19 39: p. 24.
Sargassum substrates: i3. natans I, S. natans IX, S^. fluitans III, S.. fluitans X, Sargassum sp., S_, filipendula, S_. bermudense, S. polyceratium.
Description: Hydroids minute, about 1 mm, unbranched, clavate, hydranth about as along as pedicel. Tentacles short, capitate, about 20-50 in number, scattered about the hydranth. Perisarc
usually annulated or wrinkled basally, sometimes throughout.
Medusa buds borne proximally on the hydranth among the
tentacles.
Remarks: While zooids of Zanclea costata were found on all parts of the Sargassum thallus, largest numbers were recorded on the stem. There also appears to be some relationship between Z. costata and the occurrence of the bryozoan 19
Membranipora tuberculata, to which it is frequently attached.
Russell (19 53) pointed out that Z_. costata and gemmosa are
synonymous.
Known Range: Massachusetts to the Caribbean Sea.
Family Clavidae
Rhizogeton fusiformis Agassiz, 1862 Plate I, Figure 1
Rhizogeton fusiformis Agassiz, 1862: p. 224-226, 347.
Sargassum substrate: S. ramifolium
Description: Hydranth clavate, 1-2 mm in length, rising from a fine network of intertwining stolons; about 16 filiform
tentacles scattered over distal half of hydranth. This perisarcal. covering visible on most specimens.
Gonothecae not present.
Remarks: These colonies closely resembled those described by Fraser (1944) from the New England coast. Joyce (1961) reported R. fusiformis from the Seahorse Key area and illustra ted specimens, similar to those observed on Sargassum. This unlikely tropical-to-boreal distribution suggests that per haps two separate species might exist, therefore, assignment of this Sargassum form to Rhizogeton fusiformis is tentative.
This species was reported three times from very small pieces of what appeared to be Sargassum ramifolium, where it was the usual dominant and invariably present.
Known Range: (uncertain) Cape Cod to Seahorse Key, Florida. 20
Suborder Filifera Family Bougainvilliidae
Garveia humilis oilman, 1877) Plate I, Figure 6
Bimeria humilis Allman, 1877: p. 8, pi. 5, fig. 3,4.
Sargassum substrates: £3. po ly c er a tium, £. hystrix
Description: Colonies small, 3-5.5 mm in height, rising from slightly wrinkled, creeping stolons. Pedicels generally solidary but occasionally with secondary pedicels and hydranths.
Perisarc coarse and wrinkled, especially at base of stem and latteral branches; thinning out at base of hydranths, exact point of its termination not easily discernable. Tentacles filiform, about 18 in number, arranged in a single whorl about base of pyriform hydranth. Colonies golden brown in color.
Two to three sessile gonophores, each apparently con taining a single, large egg, usually found attached to mesial region of stem.
Remarks: Vervoort (1968) observed that Bimeria humilis belongs to the genus Garveia Wright, 1859, as characterized by sessile gonophores and nude tentacles. The genus Garveia is distinguished from Bimera Allman in lacking a perisarc covering on the proximal portion of the tentacles.
Not common on Sargassum, occurring twice, each on benthic forms. Not previously reported from Sargassum.
Known Range: Tortugas, Florida, Caribbean Sea, Gulf of Mexico. 21
Order Thecata (Calyptoblastea) Family Haleciidae
Halecium nanum Alder, 1859 Plate II, Figures 8,9
Halecium nanum Alder, 1859: p. 355; Jaderholm, 1903: p. 267; Fraser, 1912: p. 367, 368, fig. 29; Stechow, 1919: p. 36 O C ... Bennitt, 1922: p. 245; Hentschel, 1922: p. 4; WingS, 192 p. 13; Timmermann, 19 32: p. 29 6; Leloup, 19 35: p. 8.; Leloup, 1937: p. 96; Burkenroad, 1939: p. 24; Fraser, 194 4: p. 198-200, pi. 37, fig. 177; Defenbaugh and Hop kins, 19 73: p. 99, pi. 12, fig. 45; Morris and Mogelberg, 1973: p. 16, fig. 18. Halecium marki Congdon, 1907: p. 474, fig. 21-23.
Sargassum substrates: S. natans I, S^. fluitans III, S^. flui tans X, S. polyceratium, S_. filipendula.
Description: Mature colonies reaching a length of 3 mm, growing in tangled masses generally restricted to more pro tected regions of Sargassum; smaller colonies, usually with single hydrophores, often present on more exposed surfaces.
Colony growth originating from original pedicel and forming new branches from short apophyses situated near hydrophore or hydrophore pedicel duplication. Branching irregular, not restricted to a particular plane, although apophyses usually situated on same sides of pedicels. Most preserved material white, some pale yellow colonies present.
Gonothecae borne in same manner as lateral branches; on a short apophysis situated near hydrophore. Female gono thecae ovate on one side, usually containing 2 large rounded ova, attached side straight, extensively annulated, slight vertical constriction dividing the annulations in half. Two small hydranths extending through a distal hydrophore of 22
gonotheca, male gonothecae smaller, ovate, broadly rounded distally.
Remarks: h . nanum was by far the most common member of the
Haleciidae on Sargassum. This species generally assumed two morphological forms and two locations on Sargassum. A dense, tangled mass of polyps reaching a length of 3 mm was restricted to the more protected regions of Sargassum while
a wilder, spreading colonial form of shorter polyps occurred on exposed surfaces of the algae. This arrangement most likely results from wave action or by predators grazing on the exposed surfaces of the algae.
Known Range: Nantucket, Bermuda, Bahamas, Gulf of Mexico.
Halecium sp. A Plate II, Figures 10, 11
Sargassum substrate: S. polyceratium.
Description: Colonies about 5 mm long, rising from short apophyses, stems divided into slender internodes, about same diameter throughout. Apical portion of each internode slightly widened, hydrophore moderately flared, well developed, with about 14 puncta. Internodes supported by 1-2 short apophyses situated below hydrophore. Internodes sometimes interrupted by slight bends (joints?) with what appear to be straight septa. Hydranth long, bulbous beneath filiform tentacles, tentacle number about 15.
Gonothecae given off similar to lateral branches. Female elongate, pyriform, supported by curved tube containing two 23
hydranths. Each gonangium with 4 large ova. Male colonies
not present.
Measurements (in microns):
Internode, total length 345-1181 diameter of base 49-89
Hydrotheca, depth (margin-diaphragm) 39-49 diameter at margin 79-99
Gonotheca, total length 985-1015
Remarks: This slender, delicate Halecium would not be ex
pected to survive long in the pelagic state. It was found
once, in fair condition on S. polyceratium. It closely re
sembles the boreal species H. tenellum in the morphology of
the colony and H. nanum in the shape of the female gonothecae,
which is more curved than H. nanum on the side containing
the hydranths. Also, the numerous fine annulations of H.
nanum are missing here and there are usually four ova present
as opposed to 2 in H. nanum.
Known Range: Gulf Stream, 29°30'N 78°29'W on floating
Sargassum.
Halecium sp. B Plate II, Figure 12, 13
Sargassum substrate: S. polyceratium
Description: Colonies small, about 0.35 mm long, rising
singly from a short apophysis, base with 2-4 distinct, wavy annulations/ separated from apophysis by a straight septa.
Pedicels widened distally, margin widely flared, curved upward,
distinctly saucer-shaped in appearance. Puncta small, usually 24 concealed by hydranth, about 20-30 in number. Tentacles filiform, short, numbering about 15.
Female gonotheca short, oblong, annulated at base, sinuous throughout, sharply rounded at apex.
Measurements (in microns):
Hydrophore, total length 187-207 diameter at base 69-79
HydrOtheca, depth (margin-diaphragm) 10-30
*! Diameter at margin 128-168
Gonotheca, total length 690-778 diameter (mesial) 168-197
Remarks: This apparently new species was found once on the blades of floating Sargassum polyceratium located in the Gulf
Stream at 29°30'N 78°29'W. Because of its very small size and the nature of its growth: sparse colonies always re maining close to the blade surface, it is easily overlooked even on the smooth surface Sargassum blades.
Known Range: Gulf Stream, 29°30'N 78°29,W on floating
Sargassum.
Family Campanulariidae
Clytia cylindrica L. Agassiz, 18 62 Plate III, Figures 14, 15
Clytia (Platypyxis) cylindrica L. Agassiz, 1862: p. 306, pi. 23, fig. 8, 9. Clytia cylindrica Fraser, 1912: p. 358, fig. 16; Fraser, 1944: p. 134, pi. 23, fig. 106; Defenbaugh and Hopkins, 1973: p. 74-76, pi. 7, fig. 26; Morris and Mogelberg, 19 73: p. 11, fig. 6. Campanularia (Clytia) cylindrica WingS, 192 3; Germain, 1935: p. 13. Laomedea cylindrica Leloup, 1937: p. 100, fig. 5. 25
Sargassum substrates: natans I, S. fluitans III, polyceratium, 5. pteropleuron.
Description: Colonies small unbranched, 1-2 mm in length, rising from smooth stolons and slender pedicels, pedicels annulated proximally and distally. Hydrotheca cylindrical, tapering abruptly at the diaphragm. Margin with 10-12 sharp
triangular teeth. Annulations 1-2 beneath hydrotheca generally quite distinct, giving these distal segments a characteristic globular appearance.
Gonothecae smooth, cylindrical, borne on short annulated pedicels, tapering slightly just below truncate distal end.
Remarks: Relatively few specimens of C. cylindrica were observed in the present study and little morphological variation was seen. However, when large quantities of the hydroid are examined, C. cylindrica, like C. hemisphaerica and others, displays a considerable degree of variation
(Defenbaugh and Hopkins, 1973), and again problems of species separation appear. Vervoort (196 8) pointed out the possible confusion of C. cylindrica with hemisphaerica and also the similarities between C. cylindrica from Guatemala and
C. elsaeoswa1dae Stechow, 1914. Defenbaugh and Hopkins
(1973) discussed similarities and differences bewteen C. cylindrica and G. coronata, Clarke, 1879, Gonothyraea gracilis
Sars, 1851, and Clytia hesperia Torrey, 19 04.
Therefore, as in the case of C. hemisphaerica, there is the possibility of some error in separating this species from other forms having similar structure. 26
Known Range: New England, Bermuda, Caribbean Sea, Gulf of
Mexico.
Clytia fragilis Congdon, 1907 Plate III> Figure 16
Clytia fragilis Congdon, 1907: p. 470, fig. 13; Bennitt, 1922: p. 247.
Sargassum substrate: S_. polyceratium.
Description: Single colony 3 mm long, internodes annulated proximally and distally. Pedicels of hydrothecae short, with
3-5 annulations. Hydrothecae long, slender, deeply tumbler shaped, diaphragm high, distinct. Margin with about 14 acute teeth separated by concave incisions, giving margin a sinuous or scalloped appearance in cross-section. Lines run ning downward through teeth formed by sharp marginal folds.
Gonotheca not present.
Measurements (in microns):
Hydrotheca, total length 837-92 6 diameter at margin 276-29 6
Remarks: Colony closely resembled that described by Vervoort
(1968) as Laomedea tottoni Leloup, 1935 from Cartagena in the
Caribbean. Found once on benthic Sargassum.
Known Range: Cape Hatteras to coast of Texas.
Clytia gracilis gars, 1851) Plate IV; Figure 21
Gonothyraea gracilis Sars, 1851: p. 138. Gonothyraea crracilis Fraser, 1912: p. 361, fig. 20; Fraser, 1944: p. 148, pi. 26, fig. 121; Morris and Mogel berg, 1973: p. 15, fig. 12. 27
Sargassum substrate: S_. natans I.
Description: Colonies miniature, growing from a creeping hydrorhiza. Pedicels unbranched, extensively annulated proximally and with 2-3 annulations beneath hydrotheca, mesial region smooth or very slightly wrinkled. Hydrothecae long, slender, tapering proximally, with a slight constriction at diaphragm. Margin with about 8 large, triangular teeth, separated by rounded incisions, margin slightly undulated in cross section.
Gonothecae not present.
Measurements (in microns):
Hydrotheca, total length 433-46 3 diameter at margin 207-227
Remarks: Identification was based on two immature specimens and it may have been confused with Clytia cylindrica (L.
Agassiz, 1862), which it closely resembles. Millard (1966) synonymized Gonothyraea gracilis and Campanularia j ohnstoni
Alder, 1856, with Clytia hemisphaerica (Linnaeus, 1767) based on studies of the varibility in Clytia (Campanularia) johnstoni shown by Ralph (19 57). Ralph showed a correlation between geographical latitude and the shape and size of the marginal teeth and the annulation of the gonotheca. Vervoort (196 8) placed Clytia compressa Totton, 19 30 and Campanularia rariden- tata Alder, 1862, in synonymy with C. hemisphaerica but ex cluded Laomedea gracilis M. Sars, 1851 (=Campanularia pelagica
Van Breemen, 190 5) based on the almost total pelagic state of L. gracilis and the usually fixed state of C. johnstoni. 28
Vervoort further noted non-occurrence of intermediate types of L. pelagica.
Found once on pelagic Sargassum.
Known Range: New England, Cape Romano, Florida, Caribbean
Sea, Gulf of Mexico.
Clytia hemisphaerica (Linnaeus, 1776) Plate III, Figures 17, 18
Medusa hemisphaerica Linnaeus, 1767.’ Campanularia johnstoni Leloup,:1937: p. 97, fig. 3. Clytia bicophora Burkenroad, 19 39: p.. 24 Clytia johnstoni Fraser, 1912: p. 358, fig. 17; Hentschel, 1922: p. 4; Bennitt, 1922: p. 248; Fraser, 1944: p. 138, pi. 24, fig. Ill; Defenbaugh and Hopkins, 1973: p. 78, pi. 8, fig. 29; Morris and Mogelberg, 19 73: p. 11, 12, fig. 7.
Sargassum substrates: S. natans I, S. natans IX, fluitans III, S. fluitans X, Sargassum S_. sp. , ramifolium, S. filipendula, polyceratium, S. pteropleuron,- !S. hystrix.
Description: Colonies generally small, about 3 mm, but sometimes attaining a length of 5 mm, pedicels unbranched, growing from creeping stolons, pedicels narrow, 51-86 y wide, in diameter, annulated proximally, distally and sometimes hav ing several mesial annulations or wrinkles. Hydrothecae deeply campanulate, 394-640 y long, 296-424 y wide, diaphragm distinct, hydrothecae frequently constricted below diaphragm.
Margin with 12-14 deeply cut, triangular teeth.
Gonothecae cylindrical, distinctly corrugated, truncate, distally attached to the stolon, or rarely to the stem, by a short annulated pedicel.
Remarks: Clytia hemisphaerica is a morphologically variable 29 species on Sargassum; variations from the general description above are relatively common. The hydrotheca may be cylindri cal or slightly flared at the margin, teeth may be acute or moderately rounded, and the hydrothecae often have constric tions of varying degrees at the diaphragm.
Ralph (1957) also described the variability of C. hemisphaerica found along the New Zealand Coast and suggested that Clytia clyindrica might be a synonym for that species.
Vervoort (19 6 8) and Calder (19 71), however, have retained
C. hemisphaerica and C. cylindrica as separate species.
I found C.i cylindrica on Sargassum with gonothecae distinctly different from those of C. hemisphaerica. (Fig. 15).
The overall paucity of gonothecae, particularly on C. cylindrica, has made the separation of these two species extremely difficult and, therefore, questionable in some instances. It does appear that C. hemisphaerica occurs with a much greater frequency on pelagic Sargassum than
G. cylindrica. Furthermore, in view of these findings, reports of C. cylindrica being “common" on Sargassum
(Morris and Mogelberg, 19 73) are questionable.
Additional complications regarding the taxonomy of hemisphaerica are discussed in Calder (1971):
Clytia johnstoni has long been known to be the hydroid of the medusa Phialidium hemisphaericum, but only recently (Millard, 1966) has the name Clytia hemisphaerica been put forward for the hydroid. Vervoort (19 68) concurred with Millard in the proposed name change. Curiously, the medusa, very common in Europe, has.never been reported on this coast, while the hydroid, reported as C. johnstoni by Fraser (1944) and others, is well known. This discrepancy suggests that the 30
North American hydroid reported as C. johnstoni may actually belong to another species, and a clarifying taxonomic study is needed.
Known Range: Bermuda, Gulf of Mexico.
Clytia noliformis (McCrady, 1857) Plate III, Figures 19,20
Campanularia noliformis McCrady, 1857: p. 92, pi. 11, fig. 4; Winge, 1923: p. 13; Germain, 1935: p. 13; Leloup, 1935: p. 29; Kramp, 19 43, p. 43. Clytia simplex Congdon, 1907: p. 471, fig. 14, 15. Clytia noliformis Smallwood, 1910: p. 137; Fraser, 1912: p. 359, fig. 19; Nutting, 1915: p. 57, pi. 11, fig. 7-10; Bennitt 1922: p. 248; Timmermann, 1932: p. 296; Burken- road, 19 39: p . .2 3; Fraser, 194 3: p. 88; Fraser, 19 44: p. 144, pi. 26, fig. 117; Defenbaugh and Hopkins 19 73: p. 80, 81, pi. 9, fig. 31: Morris and Mogelberg, 1973: p. 13, fig. 9. Clytia volubilis Hargitt, 1909: p. 373, fig. 4. Campanularia (Clytia) noliformis Vervoort, 196 8: p. 11, fig. 2. -
Sargassum substrates: S_. natans I, S_. fluitans III, S. flui tans X, Sargassum S. sp., bermudense.
Description: Stolon creeping and interwining on thallus of
Sargassum, giving rise to pedicels 2 to 3 mm long, rarely as much as 5.5 mm in length. Pedicels generally unbranched, annulated both proximally and distally, often extensively annulated or sinuous throughout the entire length of the pedicel.
Globular segment always found under each hydrotheca.
Hydrotheca broadly campanulate, usually of similar depth and width, margin with about 12 shallow teeth. Basal chamber thick, rounded, lacking basal diaphragm; about 25 tentacles.
Gonothecae almost sessile, growing from stolon to a height of about 1 mm, shape variable but generally broadly ovate, margin greatly rounded at apex, apex with a distinct, 31
cap operculum,
Mec s (inomicrons):
er at margin 34 5-39 4
i hydrotheca 365-522
Rer. "his was by far the most comir 1 on the e eup irgassum natans and in the cc is a whole.
It ally extremely abundant on S, and was
als ted from S_. fluitans types II nd from two
ber rgassum forms.
Knc e: New England, Bermuda, Car ;a', Gulf of
Me:.
Campanularia sargassicola (N; ! 15 } Plate IV, Figures 22, 23
Civ gassicola Nu11ing, 1915: p. !. I, f ig. B , 9. nularia sargassicola Leloup- 30.- el la sargassicola Fraser, 19 -• 1, pi. 26, 120; Morris and Mogelberg, 19 .3, 15, fig. 11.
Sar substrates: S. polycerati urn,, 3endula, .eropleuron, S_. hystr ix.
Des mz Colonies about 1.5 mm lore 3ls arising
fror :h stolons. Perisarc wavy, wit spicuous
glo: mnulation beneath the hydroth>- itional
anr. is often found scattered a lo n g Hydrotheca dec? ipanulate, length about 1.5 ti i. Perisarc of ;eca and pedicel extremely thi Lng a basal
. "pr iphragm", then tapering abrup ■se of teeth.
T h . about 13 equally rounded tee :ed by incisions of size and roundness, except - truncate one hydrothee
asurements (in •>:
Hydrotheca, diamete rgin)
Pedicel, di
marks: C . sar a along wit aria margare
s one of the it aspread hydr the benthic
rgassum forms. alonies were ly small and
ricted to the agions of th A single
ving truncate as found in normal pol\
rhaps suggest:! gh degree of phism for tr
secies.
sown Range: C<: eras, North , Caribbean
Obe 1 j na Clarke, 1 Plate gures 24, 2 5 aelia hyalina C 1879: p. 241 , fig. 21: Ni 1895: p. 30 raser, 1912: Lg. 24; Benn: 1922: p. 2, ermann, 19 32 1; Fraser, IS p. 160, pi, g. 131; Morr logelberg, IS p. 16, fig. Obelia conge gitt, 1909: Kingsley, IS p. 271 Laomedea se Hentschel, 1 4; Leloup, p. 24. Laomedea (c congdoni Ver 1968: p. 23. argassum substi S. natans I ans IX, S_. f_. III, S. fl; Sargassum sr alyceratium, G . pteropl ’ * f ilipendu-j amifolium, S mudense. ascription: C' about 8 mm I eguently to nailer colonic red, longer 3 in tangled ranching irrec geniculate, with annul, t base and abc n of each 1 leniculate ; 33 annulated at base and below hydrotheca, shorter branches may be ringed or wrinkled throughout. Hydrotheca campanulate or triangular, of similar length and width or slightly longer than wide, margin entire. Diaphragm distinct, tilted.
Basal region of stem amber.
Gonotheca clavate, axillary, on short annulated pedicels.
Small terminal apical collar on fully developed specimens, immature gonothecae flat or rounded apically, lacking terminal collar.
Measurements ( in microns):
Hydrotheca/ total length 217-345 diameter (at margin) 246-296
Gonothecae, total length 690-788 diameter (maximum) 197-246
Remarks: From the literature (Nutting, 1915, Fraser, 19 44,,
Defenbaugh and Hopkins, 19 73) Obelia hyalina and O. dichotoma
(Linnaeus, 1758) were almost inseparable. Close examination of O. hyalina and O. dichotoma (specimens in the collection of D. R. Calder from Cape Cod Bay) at 15Ox, however, revealed the presence of small rounded teeth at the margin of O. dichotoma while the margin of O. hyalina was always entire.
Known Range: New England, Bermuda, Caribbean Sea, Gulf of
Mexico*
Incertae sedis
Cuspidella humilis (Alder, 18 62) Plate IV, Figure 2 6
Campanularia humilis Alder, 1862: p. 239. 34
Sargassum substrate: S_. pteropleuron.
Description: Minute, tubular hydrothecae rising singly
from a slender stolon at regular intervals, operculum with
low conical roof of about 10 facets. Hydranth relatively
large, about equal in length to hydrotheca when extended; with a distal whorl of about 10 small tentacles.
Gonothecae not present.
Measurement (in microns):
Hydrotheca, length 207-24 6 Width 69-96
Remarks: Not previously reported on Sargassum. Found once
on S. pteropleuron.
Known Range: 41°25"N, 65°50,18,fW, Caribbean Sea.
Family Hebe11idae
Scandia mutabilis (Ritchie, 1907) Plate V, Figure 27
Campanularia mutabilis Ritchie, 190 7. Scandia mutabilis Fraser, 1912: p. 372; Fraser, 1944:, p. 208, pi. 39, fig. 187; Stechow, 1919: 79; Leloup, 1935: p. 17; Morris and Mogelberg, 1973: p. 16, fig. 20. Laomedea michaelsarsi Leloup, 1935: p. 17.
Sargassum substrate: S. pteropleuron.
Description: Colonies about 1 mm, unbranched, rising singly from a smooth stolon. Pedicels with strong spiral annulations, about same length as hydrotheca. Hydrotheca subcylindrical with shallow corrugations and a distinct, flat rim at the margin, diaphragm distinct. Perisarc thick throughout the pedicel and hydrothecal base before tapering distally. 35
Gonotheca not seen.
Measurements (in microns):
Hydrothecae, length 9 75-1330 diameter at margin 591-640
Remarks: S_. mutabilis was found on Aglaophenia latecarinata; only a small portion of its hydrorhiza was attached to the
Sargassum. It was also reported from Aglaophenia on Sargassum
and directly from Sargassum by Fraser (1912) at Beaufort,
North Carolina, and by Stechow (1919) from the Gulf of Mexico.
Known Range: Beaufort, North Carolina (Sargassum), Caribbean
Sea, northern Gulf of Mexico.
Family Sertulariidae
Dynamena mayeri (Nutting, 1904) Plate V, Figure 28
Sertularia mayeri Nutting, 1904: p. 58, pi. 5, fig. 1-4; Hentschel, T922: p. 4; Burkenroad, 19 39: p. 23; Fraser, 1944: p. 285, pi. 61, fig. 272; Defenbaugh and Hopkins, 1973: p. 106, 107, pi. 14, fig. 53.
Sargassum substrates: S_. fluitans III, S. fluitans X, S. pteropleuron.
Description: Colonies small, delicate, about 4-6 mm long, apophysis with 1-2 oblique joints distally, rising from a smooth, creeping stolon. Hydrocaulus divided into hydrothecate internodes by transverse septa above each hydrotheca pair.
Free space between hydrothecae pair greatest on posterior side, hydrothecae often contiguous (as much as 2/3 of the total length of adcauline wall) anteriorly. Proximal hydrothecae curved mesially, free part of abcauline wall at 2 to base Distal 3ca with
abcauli: parallel , angle I
of adcau' I and ste ;han that
othecae. with 2 1 .eral ten
iline to arculum < oy an adc plate
.ltly sma. auline pi
heca not
ts ( in ;
oaulus, at node 12 8-13' ength in 512-8 8" ength ab wall 29 6-44 3 ength fr abcaulin 69-14 ength ac t adcau1 305-40 ength fr. adcauline 197-2 7^ iameter ture 118-147
Found s i on benth elagic S r
n on S_. ;uron. Tr ies clos-' mb led
erasmo1 cci) as c d by Joyc )
rse Key, Owing larities
ecies an ■curence e on Sarg must
iy identi i tentatie
:e; Berm ibbean Sc eston Bap
Dynamer Ldentata f id Soland' Plate ^ a 29
1 quadric 311 is and. ir, 1786: ;, fig. C ;hea quae, pa Fraser p . 372, mmann , 29 6; Bur 1939: p -hea q u a -v. ^a var. r irgitt, I 4, fig» i quadri ’raser, 3 252, pi. 37
Dynamena quadridentata var. nodosa Van Gemerden-Hoogeveen, 1965: p. 27. Dynamena quadr ident ata Vervoort, 1968: p. 41, 42, fig. 19? Morris and Mogelberg, 197 3: p. 22, 23, fig. 34 a,b.
Sargassum substrates: S_. fluitans III, Si. pteropleuron.
Description: Colonies about 6 mm in length, hydrocaulus unbranched, divided into hydrothecate internodes by oblique nodes, athecate internodes lacking. Hydrocaulus arising from stolon on a short apophysis terminating in a conspicious oblique joint, proximal internode having a single pair of opposite hydrotheca as does second internode in most specimens.
Successive hydrothecate internodes with as many as 3 pairs of opposite hydrothecae. Margin indistinct, with variable abcauline and adcauline teeth or thickenings.
Gonothecae not present.
Measurements (in microns):
Hydrotheca, width 542-611 Hydrothecate internode length 887-1300
Remarks: Only 6 small colonies, in fairly poor condition, were found in the collections. These colonies comply with
Hargitt's (1908) description of Dynamena quadridenta var. nodosa. A slight difference exists between the present material and that described by Van Gemerden-Hoogeveen (1965); only very weak constrictions of the perisarc are visible in the present material and it cannot be certain if these acutally constitute "transverse nodes" (Van Gemerden-Hoogeveen, p. 28).
It does not appear that these internodes, if they exist, are athecate, however, Van Gemerden-Hoogeveen examined material 38 from several stations and reported a great deal of variation.
Found twice on both Sargassum benthie and pelagic.
Known Range: Woods Hole (Sargassum), Bermuda, Caribbean Sea.
Sertularia inflata (Versluys, 1899) Plate VI, Figures 30, 31
Desmoscyphus gracilis Allman, 188 8: p. 71, pi. 34, fig. 2-2c. Desmoscyphus inflatus Versiuys> 1889: p. 42, fig. 11- 13. Sertularia versluysi Nutting, 1904: p. 53, pi. 1, fig. 4-9; Congdon, 1907: p. 481; Hargitt, 1908: p. 112; Kingsley, 1910: pi 31; Fraser, 1912: p. 375, fig. 40; Hentschel, 1922: p. 4; Burkenroad, 1939: p. 23. Sertularia inflata Fraser, 1944: 283, pi. 61, fig. 271; Morris and Mogelberg, 19 73: p. 24, fig. 40 a-e.
Sargassum substrates: S_. natans I, S. fluitans III, £>. pteropleuron, S^. filipendula, Sargassum sp.
Description: Colonies about 11 mm long, monosiphonic, situated on a long apophysis rising from a dense hydrorhizal network.
Hydrocaulus separated from apophysis by a large, conspicuous, oblique joint, thereafter separated by similar, but less con spicuous joints. Each internode with two hydrothecae on one side of stem, one basal, the other alternate, mesial. Distally, mesial hydrotheca and alternate distal hydrotheca arranged pro gressively more opposite, yet always remaining alternate.
Branching regular, alternate, situated on distinct apophysis between basal joint and basal hydrotheca of each internode.
Branches separated by transverse septa; hydrothecae strictly opposite, contiguous anteriority; separated by a free space posteriorly, distal half bent, with concave side indented.
Margin with two teeth, abcauline tooth small, inconspicuous, 39
operculum of two flaps.
Gonotheca not present.
Measurements (in microns):
Hydrocaulus, diameter at node 148-168 length (branched) internode 788-1133
Hydroclade, length apophysis 197-345 diameter at node 69-89 length internode 443-640
Hydrotheca, length abcauline wall 187-217 length free part adcauline wall (hydrocladia) 128-158 length contiguous part adcauline wall (hydrocladia) 158-197 diameter at aperature 89-99
Remarks: Colonies closely resembled those described by
Nutting (19 04) and Fraser (1944) in having oblique septa rather than straight septa between the internodes as de scribed by Van Gemerden-Hoogeveen (1965) and Vervoort (1968)).
Differences between these species and S_. marginata (Kirchenpauer) discussed by Van Gemerden-Hoogeveen (1965) were not discernable and it is possible that S. marginata, if a separate species, could have been overlooked.
Found nine times on benthic and pelagic Sargassum, one of four dominant species on S. pteropleuron; occurring on 75% of four S. pteropleuron samples.
Known Range: New England (Sargassum), Bermuda, Caribbean
Sea, gulf coast of Texas.
Sertularia stookeyi Nutting, 1904 Plate VI, Figures 32,33 40
Sertularia stooeyi 1904: p. 59, pi. 5, fig. 6-7; Fraser, 1912: p. 375, fig. 39; Bennitt, 1922: p. 251; Fraser, 1944: p. 288, pi. 61, fig. 275; Morris and Mogelberg, 19 73: p. 24, 25, fig. 42;
Sargassum substrates: !S. polyceratium, _S. f ilipendula.
Description: Colonies small, delicate, unbranched, about
3 mm in length, growing from creeping hydrorhiza. Hydrocaulus
separated from basal apophysis by a pair of oblique joints,
divided distally by straight septa and randomly placed
oblique joints. Internodes relatively long for such a de
licate hydroid; hydrotheca pairs medially arranged, contiguous
anteriorly; separated posteriorly. Mesial diameter of hydrothecae slightly enlarged, distal portion (freepart) oblique
in relation to hydrocaulus, narrow, terminating in a thin margin with 2 teeth. Operculum closed by an adcauline and an
abcauline flap of similar size.
A single, empty gonotheca observed on face of hydrocaulus of one specimen below proximal hydrotheca pair; smooth, oval, distinct collar and large operculum.
Measurements (in microns):
Hydrocaulus, diameter at node 39-59 length internode 365-562 length abcauline wall 148-197 length free part of abcauline wall 96-12 8 length adnate part adcauline wall 59-12 8 length free part adcauline wall 118-19 7 diameter at aperature 49-59
Remarks: Not common Sargassum, found twice on benthic forms where it was one of two dominants on S. polyceratium;
occurring on three of four samples.
Known Range: Vineyard Sound, Bermuda, Caribbean Sea. 41
Sertularella parvula (Allman, 1888 ) Plate V I , Figure 34
Calamphora parvula Allman, 1888; p. 29, pi. 10, fig. 3, 3a. Thyroscyphus intermedius f. peculiaris Leloup, 1935: p. 33, fig. 15-17. Thyroscyphus intermedius Fraser, 1944: p. 181, pi. 33, fig. 156.
Sargassum substrates: S_. pte ropleuron, S. polyCeratiurn.
Description: Colonies small, about 1 mm high, hydrothecae
given off singly at regular intervals from a creeping stolon,
less frequently with 2-3 alternate hydrothecae given off from
a hydrocaulus. Hydrothecae cylindrical, slightly contracted
near apex, with about 7 weak or distinct annulations, re
sulting in a corrugated appearance. Teeth four, low separated,
from pedicel by a thick septum.
Gonothecae not present.
Measurements (in microns):
Hydrotheca length 640-1133 width 296-315
Remarks: An excellent description of this species is provided by Vervoort (1968). According to Vervoort, the genus
Calamphora is considered to be obsolete based on the separate hydrothecae rising from the hydrorhiza in the established
species Sertularella tenella (Alder, 1856). Also, separation of Calamphora parvula Allman, from this species is not just
ified based only on the presence of four knobs on the gonotheca or the presence or absence of intrathecal teeth.
This species was found once on S. pte r op'leuron and S. polyceratium. Small but distinct colonies were found growing 42 on and near the stew of the algae.
Known Range: Bermuda,. Caribbean Sea,
Family Plumulariidae subfamily Halopterinae
Antennella secundaria (Gmelin, 1791) Plate VII,. Figures 35, 36
Sertularia secundaria Smelin, 1788-1793: p. 3854. Antenella secundaria Leloup, 19 35: p. 53; Fraser, 1944: p. 317, 138, pi. 66, fig. 302; Pennycuik, 1959: 176, 177, pi. 3., fig. 5, 6; Van Gemerden- Hoogeveen, 1965: p. 54-56, fig. 29-31.
Sargassum substrate: *3. polyceratium.
Description: Hydrocauli short, 2-3 mm, unbranched, rising from a somewhat wavy, irregularly branched stolon. Basal portion of hydrocauli with 1-5 nematothecae, divided into 1-3 inter nodes of variable length by transverse nodes. Hydrothecate internodes with a single cup-shaped hydrotheca and five nema tothecae: a mesial nematotheca below hydrotheca, two lateral nematothecae, one reduced nematotheca between lateral nema totheca ( in axil of hydrotheca and internode) and 2 mesial nematothecae above hydrotheca. Hydrothecate internodes separated by oblique nodes situated under lower mesial nematotheca; in complete transverse septa or peridermal constrictions between lateral nematotheca and reduced mesial nematotheca.
Gonothecae not present.
Measurements (in microns):
Hydrocaulus, interval between two oblique nodes 640-788 length intermediate non-hydrothecate internode 34 5-443 43
Hydrotheca, length abcauline wall 118-187 length free part adcauline wall 108-118 total height 197—246 diameter at margin 187-217
Remarks: These colonies closely resembled those taken
& - on Sargassum in Queensland, Australia, by Pennycuik (1959)
The abcauline wall of the hydrothecae and the dorsal and ventral walls of the hydrocaulus are conspicuously thick.
Van Gemerden-Hoogeveen (1965) provided an excellent de scription of this species as well as Antennella diaphana
Heller, 1868, and Antennella curvitheca Fraser, 1937.
These specimens also compared favorably to those taken by Van Gemerden-Hoogeveen in the Caribbean with respect to size and morphology, with the exception of the intermediate non-hydrothacate internode which, in the present study, is about twice the length of that described by Van Gmerden-
Hoogeveen.
Known Range: Caribbean Sea, Dry Tortugas.
Halopteris diaphana (Heller, 1868) Plate VII, Figures 37, 38
Aniscocalyx diaphana Heller, 1868: p. 42, pi. 2, fig. 5. Plumularia alternata Nutting, 1900: p. 62, pi. 4, fig. 1,2; Congdon, 1907: p. 484; Fraser, 1912: p. 381, fig. 48. Plumularia diaphana Bennitt, 1922: 254, Fraser, 1944: p. 342, pi. 73, fig. 331; Deevey, 1950: p. 347; Morris and Mogelberg, 1973: p. 19, 20, fig. 2 8 a,b. Antennella diaphana f. typica Leloup, 1935: p. 52. Antennella diaphana diaphana, Van Gemerden-Hoogeveen, 1965: p. 497 fig7- 23-28.
Sargassum substrates: S_. natans I, S_. pteropleuron, IS. poly- ceratium, S. bermudense. 44
Description: Colonies 4-6 mm in length, hydrocaulus monosi^- phonic, rising on a long apophysis, separated into internodes by straight septa, each bearing 0-2 nematothecae. Apophysis attached to basal hydrothecate internode by an oblique node.
Cauline hydrothecae situated proximally on internode. Nema tothecae 5 per internode: 2 lateral beside cauline hydrotheca,
1 below cauline hydrotheca, 1 auxiliary nematotheca, and 1 located near apical joint. Hydrocladia borne on Alternating right and left apophyses originiating near hydrothecae. Hy drocladia divided into alternating athecate and thecate inter nodes, proximal internode athecate. Athecate internodes with transverse nodes, distal nodes oblique. Athecate internode with one mesial nematotheca, thecate internode with two large lateral nematothecae on each side of the hydrothe- cal margin, a mesial nematotheca proximally to hydrotheca, and usually a very small nematotheca situated between lateral nematothecae between ventral wall and margin of hydrotheca.
Gonothecae not present.
Measurements (in microns):
Hydroclade, distance between oblique nodes 44 3-591 length athecate internode 19 7-345
Hydrotheca, length abcauline wall 19 7-246 length adcauline wall 59-9 8 diameter at margin 227-256
Remarks: Based on Millard's (1962) classification the genus
Halopteris is used since cauline hydrothecae are present.
Calder (personal communication) believed this species and
Schizotricha tenella not to be synonymous as was suggested by 45
Vervoort (1968), Calder described H. diaphana as a finer, more compact colony with unbranched hydrocladia. Also,
S. tenella appeared to be a more temperate-water species while
H. diaphana is tropical.
Known Range: Beaufort, North Carolina (on Sargassum), Ber- muda, Caribbean Sea, Northern Gulf of Mexico.
subfamily Plumulariinae
Plumularia margaretta (Nutting, 1900) Plate VIII, Figures 39, 40
Monotheca margaretta Nutting, 1900: p. 72, pi. 11, fig. 1-3; Fraser, 1912: p. 380, fig. 47; Bennitt, 1922: p. 254; Winge, 1923: p. 13; Timmermann, 1932: p. 296; Burkenroad, 1939: p. 23. Plumularia margaretta Leloup, 1935: p. 54, fig. 31; Fraser, 1944: p. 34 8, pi. 74, fig. 337; Van Gemerden- Hoogeveen, 1965: p. 69; Morris and Mogelberg, 19 73: p. 21, fig. 30 a-c.
Sargassum substrates: £. polyceratium, £3. pteropleuron, Sargassum S . sp. , S_. ramifolium.
Description: Colony small, 6 mm in length, hydrocaulus monosiphonic, regularly geniculate with 2-3 large basal annuiations divided into regular internodes by straight septa; each internode with a single mesial nematotheca and two auxiliary nematothecae. Hydrocladia borne on short apophyses situated distally on internode, proximal internode athecate, distal internode thecate and supporting a single, deeply campan- ulate hydrotheca situated between a ventral bifid support and a thick basal process, each with a distal nematotheca,
Gonotheca borne on a short pedicel below the basal hydro- cladium, deeply campanulate, distinctly corrugated, with a 46
large, flat, distal aperture
Measurement (in microns):
Hydrocaulus, internode length 246-325 • internode maximum diameter 49-59
Hydrocladia, athecate internode length 59-99 maximum diameter, athecate internode 39-49
Hydrotheca, diameter at margin 118-128
Gonotheca, diameter at aperture 473-512
Remarks: P. margaretta was the most abundant hydroid on the
benthic Sargassum, and along with Campanularia sargassicola
occupied the largest number of benthic Sargassum forms but
did not occur on eupelagic Sargassum,
Known Range: Marthas Vineyard, Bermuda, Bahama, Caribbean
Sea,
Plumularia strictocarpa Pictet, 1893 Plates VIII, IX, Figures 41, 42, 43
Plumularia strictocarpa Pictet, 1893: p. 550; Fraser, 1912: p. 3 82, fig. 51; Fraser, 1944: p. 353, pi. 76, fig. 343; Morris and Megelberg, 19 73: p. 22, fig. 33 a,b. Plumularia sargassi Vanhoffen, 1910: p. 3 33, fig. 46; Hentschel, 1922: p. 4; Leloup, 19 35: p. 55, fig. 32; Van Gemerden-Hoogeveen, 1965: p. 68, fig. 37, 38.
Sargassum substrates: natans I, S^. natans IX, S. fluitans III, SL fluitans X, Sargassum S. sp., S. polyceratium, S. pteropleuron, IS. filipendula, E. hystrix, S3. ramifolium.
Description: Colonies about 7 mm long, hydrocaulus
monosiphonic, divided into regular internodes by 2-3 trans
verse septa at each node. Each internode with an auxiliary
nematotheca and a larger basal nematotheca and a larger basal menatotheca. Hydrocladia borne on distal apophyses, alternately 47
directed in one plane with alternating athecate and thecate
internodes; each hydrocladium with a short athecate proximal
internode attached to the hydrothecate internode by an oblique
septum. Thecate internodes supporting a cup-shaped hydrotheca with supracalycine nematothecae and a single mesial nematothe
ca below hydrotheca; a single mesial nematotheca also present
on each athecate internode except the proximal.
Gonangia large, oblong, distinctly corrugated; 1-2 in number, attached basally by a tapering pedicel to face of hydrocaulus.
Measurements (in microns):
Hydrocaulus, internode length 296-325 diameter at node 49-69
Hydrocladia, length proximal internode 49-79 length hydrothecate internode 315-374 length athecate internode 14 8-217 diameter 39-49
Hydrotheca, diameter at margin 89-10 8
Remarks: The Plumularians are frequently difficult to separate
in the absense of gonothecae. P. strictocarpa closely re
sembles P. setaceoides Bale with the exception of the an- nulations between internodes found on the latter. I have also noted a great deal of similarity between the gonothecae of those specimens which I found on Sargassum and the gonothe cae of both P. strictocarpa and IP. setaceoides as described by Fraser (1944). If these are indeed two separate species,
it is possible that P. setaceoides has been overlooked in my samples as close examination of the hydrocaulus of each 48
polyp was not possible *
Known Range: Bahamas, Florida, Caribbean Sea.
Plumularia sp. Plate Xg Figures 44, 45
Sargassum substrate: S^. polyceratium.
Description: Colonies about 6 mm long, hydrocaulus monosiphonic,
attached to a long apophysis rising from hydrorhiza. Apophysis with 1-3 trumpet-shaped nematothecae, separated distally
from hydrocaulus by pronounced oblique septum. Internodes
thecate, separated by oblique septa, 1-2 alternately arranged
hydrocladia per internode, each supported by distinct apophysis
2-3 auxiliary nematotheca. Hydrocladia inserted either basal-
ly or distally (2 per internode) or mesially (one per inter node) . Thecate internodes with bonnet-shaped hydrotheca, margin greatly thickened, mesial nematotheca and supracalycine nematotheca present. Thecate internodes attached posteriorly by oblique septa and anteriorly by straight septa.
Gonothecae not present.
Measurements (in microns):
Hydrocaulus internode, length 251*-345 diameter at node 59-69
Hydroclade, length thecate internode 24 6-197 intermediate athecate internode 148-19 7 diameter at node 89-100
Hydrotheca diameter at margin 99-10 8
Remarks: This apparently new plumularian was discovered on S. polyceratium which supported 18 other hydroid species, 49
including two apparently new species of Halecium. Under
low magnification, the colonies resembled the common, yet more delicate P. strictocarpa, which may account for their being overlooked by earlier researchers and possibly in
this study on other Sargassum samples.
Known Range: Gulf Stream, 29°30rN, 78°29*W on floating
Sargassum.
subfamily Aglaopheniinae
Aglaophenia latecarinata Allman, 1877 Plate IX, Figures 46, 4 7, 4 7
Aglaophenia latecarinata Allman, 1877: p. 56; Allman, 1885: p. 151, pi. 23, fig. 56; Broch, 1914: p. 7; Hentschel, 1922: p. 4; Winge, 1923: p. 13; Timmermann, 1932: p. 296; Germain, 19 35: p. 13; Leloup, 19 35: p. 57; Leloup, 1937: p. 113; Fraser, 1944: p. 378-381, pi. 82, fig. 368; Adams, 1960: p. 81; Van Gemerden-Hoogeveen, 1965: p. 76; Vervoort, 1968: p. 72, 73, fig. 33: Defenbaugh and Hopkins 19 73: p. 116, 117, pi. 16, fig. 61; Morris and Mogelberg, 19 73: p. 17, 21 a-d. Aglaophenia minuta Nutting, 1895: p. 30, 54; Nutting, 1900: p. 96, pi. 21, fig. 1-3; Jaderholm, 1903: p. 294; Congdon, 1907: p. 483; Hargitt, 1908: p. 109; Small wood, 1910: p. 137; Fraser, 1912: p. 378, fig. 43; Bennitt, 1922: p. 252; Burkenroad, 1939: p. 23.
Sargassum substrates: S. natans I, S^. natans VIII, S_.'. flui- tans III, S_. fluitans X, S_. pteropleuron, J3. polyceratium, S. filipendula, Sargassum sp.
Description: Colonies relatively small, about 8 mm in length.
Hydrocaulus supported by a short, annulated apophysis; upper portion of stem regularly divided by oblique septa, separ
ated from basal apophysis by 1-2 large oblique nodes. Each
internode with a short upper mesial apophysis supporting a
hydrocladium, a large rounded basal nematotheca, and two 50
lesser nematothecae; a reduced basal nematotheca below,
and an auxiliary nematotheca above each hydroclade. Hydrocladia
regularly divided into internodes, with a distinct septum
opposite intrathecal ridge and another opposite supracalycine
nematotheca, Supracalycine nematothecae extending to hydrothe-
cal ridge, mesial nematotheca not extending beyond hydrothecal
diaphragm. Margin with 9 slightly rounded teeth; variable,
generally terminating distally in a pronounced, slightly
rounded tooth at margin.
Corbulae borne on basal internode, separated from
hydrocaulus by a single hydrothecate internode. Leaves
generally 6-8. Single row of teeth present along lower sur
face .
Remarks: Millard (1958) and Vervoort (1959) mentioned the variability of the marginal teeth and the shape of the hydro
thecal carina, but only slight variations were noticed on
Aglaophenia latecarinata from Sargassum. This species re
sembled Aglaophenia perforata (Allman), but is readily distinguished by the presence of marginal teeth along the base of the corbula. Common on pelagic Sargassum, found 20 times on broad-leaved S3. fluitans III and X and 4 times on narrow-leafed S^. natans I. Also found 5 times on benthic
Sargassum and twice on unidentified Sargassum.
Known Range: Beaufort, North Carolina (Sargassum), Bahamas,
Caribbean Sea, Gulf of Mexico. 51
Taxonomic Problems
Studies on the relationships of hydroids to their
Sargassum substrates are complicated by problems in the taxonomy of both hydroids and Sargassum. Hydrozoan taxonom- ically has long been plaged by the dual nomenclature created by separate treatment of polyp and medusa stages. Hydroids L also display a wide degree of geographic polymorphism.
Recent work by Russell (1953)/ Mayer (1910a, 1910b) and others in addition to updated studies of specific geo graphical areas such as those by Calder (1967, 19 70, 1971,
19 72a, 1972b) along the U. S. east coast and Vervoort (196 8) and Van Germerdeen-Hoogeveen (19 65) in the Caribbean have helped to eliminate synonymies and modernize hydrozoan classification. Other studies by Rees (1938, 1939, 1956,
1957, 1958), Ralph (1957) in New Zealand, Millard (1959,
1962, 19 64, 19 66) in South Africa and Brinckmann-Voss (1968) in the Mediterranean have also improved hydrozoan classifica tion and relationships through revisions and determinations of significant morphological features.
Identification of Sargassum species and types is dif ferent because of extensive polymorphism. This was illustra ted by Parr (19 39), who, after extensive sampling in the
Sargasso Sea, Gulf Stream, and Gulf of Mexico, covering 69 98 nautical miles and collecting nearly five thousand pounds of
Sargassum reported the occurrence of six eupelagic Sargassum forms. These include two morphological "types11 of Sargassum 52
fluitans (types III, X) and four "types" of Sargassum natans
(types I, II, VIII, IX) . Types such as S_. natans I, II, and
IX show few morphological differences as do S_. natans VIII
and S_. fluitans III. Four benthic Sargassum forms were also
reported from this area by Parr, including S. polyceratium,
S. pteropleuron, S. hystrix and Sargassum V (tentatively
identified as S^. rami folium) . In addition, I found S_. ber-
mudense and S. filipendula in the Gulf Stream. Several of
these benthic forms are difficult to separate based on
morphology, and as suggested by Parr, apparently undergo mor
phological changes while in the pelagic state. The forms
referred to as "Sargassum sp." in this study consisted of
abberrant benthic forms displaying no clear taxonomic af
finities and probably represent pelagic forms of benthic
species.
The sterile, eupelagic species S. natans and _S. fluitans
comprise over 99% of the total pelagic vegetation in the
Sargasso Sea, and of this quantity, 88-99% is made up of the
two easily distinguishable forms S^. natans I and S. fluitans
III (Parr, 1939). These forms also constitute the vast majority of my material (Appendix I).
Hydroid Distribution
Although, the relative volumes of benthic Sargassum
species in the Gulf Stream and Sargasso Sea are small, these
species harbored a considerable number of hydroid species which apparently would not exist in the area if the entire 53 algal community were comprised of eupelagic Sargassum, While no hydroid species was completely faithful to eupelagic
Sargassum species, 14 species occurred only on the benthic
forms.
A classification of 13 of the more common hydroid
species based on the occurrence on the various Sargassum types resulted in their separation into 4 distribution groups.
Group I (common pelagic species) contains two species
Clytia noliformis and Dynamena mayeri, which appear most fre quently on eupelagic Sargassum forms. C. noliformis was the usual dominant on S^ natans I and thus the most common and abundant hydroid in the collections owing to the relatively high abundance of that Sargassum type. It was also found on S. natans IX, S. fluitans III, S.flutians X, and on the
benthic forms S^. sp. and J3. bermudense. D. mayeri was
common on eupelagic Sargassum forms with the exception of
S_. natans I, where it did not occur. It also appeared on the benthic form ST. steropleuron. D. mayeri was relatively less
abundant than C. noliformis although both were apparently
capable of inhabiting any region of the thallus. The much more frequent occurrence of these two species on eupelagic
Sargassum than elsewhere suggests an., evolutionary trend towards endemism on pelagic Sargassum, particularly of
C. noliformis, which was rare on the benthic algae.
Group II (ubiquitous species) contains four species,
Clytia hemisphaerica, Plumularia strictocarpa, Zandea costata 54 and Obelia hyalina which were -ubiquitous in their distri bution and occurred frequently on both benthic and eupelagic
Sargassum forms. Each of these species displayed definite colonial arrangement on the algae. C. hemisphaerica and
Z. costata generally occurred as small, discrete colonies.
Z. costata, however was usually restricted to the older, more protected regions of the stems and was frequently found growing on the bryozoan Membranipora tuberculata. C. hemis- phaerica usually occupied the outer blades and bladders of the plant. 0. hyalina grew generally in small yet very dense clusters also on the peripheral portion of the plant, very much like 0. cichomata on Sargassum fluvellum as observed by Kato et_ al. (1961). When in close proximity to heavy growths of Clytia noliformis, colonies of the latter were generally reduced in size paralleling Kato's observations on the association of 0. dichomata -and Clytia volubilis also on S_. fulvellum. The remaining ubiquitous species, Plumularia strictocarpa, occurred in very small colonies on all regions of the thallus, but was generally situated on the peripheral portion of the plants.
Group III (less common widespread species) contained three species Halecium nanum, Aglaophenia latecarinata and
Sertularia inflata which were also not specific to benthic or eupelagic Sargassum but were not as widespread as the ubi quitous Group II hydroids. Halecium resembled Zanclea in its microhabitat distribution on the plants and S. inflata 55
resembled, P. strictocarpa, Aglaopheni a latecarinata appeared to locate on the more peripheral portion of the thallus as did 0. hyalina, and like 0. hyalina was most abundant when competition (abundance) from other hydroid species was low.
Finally, the four species in Group IV (benthic species)
Clytia cylindrica, Halopteris diaphana, Campanularia sargassicola and Plumularia margaretta had a high affinity for the benthic
Sargassum forms, although only C. sargassicola and margaretta, of these more common species, were restricted entirely to the benthic forms. P. margaretta appeared to originate on the plant stems but also grew well on the extremities. C. sargassicola was generally restricted to the stem and H. diaphana was always found on the exposed blades. C. cylindrica was most common on most regions of the thallus and generally appeared to occupy the same regions of the plant as C. noli- formis and C. hemisphaerica, yet it never occurred in such large numbers as these two species.
The hydroid species within each group ranged in form from relatively short to relatively tall (referred to as short, medium, tall) and this colony shape reflected its position on the thallus. In Group I a tall species,
D. mayeri and a species of medium height, C. noliformis, are both found on all parts of the thallus,, including the stem. In Group II are two tall species, P_. strictocarpa and 0. hyalina, generally found on the peripheral portion of the thallus, a species of medium height, C^, hemisphaerica, found parts of the thallus, a ort species.
Z. co: hich generally occupies em and older, less c regions. A. latecarina S. inflata of of Grc are tall species, occup e peripheral porti< ie plant, while H. nanum rt species, is fo1 ;he stem and the older 1 ’osed areas.
Finall Iroup IV, the peripheral >n is again usual aied by two tall species aphana and and P retta while the inner br and blades are inhab C. cylindrica, a hydro! :dium length.
As in II and III a short spec sargassicola occupy stem and other less exp :eas, A somewh simil< ngement is seen with Cly ubilis, Obelia d ichor ad Coryne uchidai on Sar fulvellum in
Japanc ers (Kato, 19 61)
Dominance and Fide <
A ed by Burkenroad (in Par )), Hentschel
(1920) Winge (19 23) , Aglaopheni zarinata and
Clytia ormis were the usual dom on S. fluitans and S. s I, respectively. Othe dtl dominants, observ Burkenroad, did not exis / samples, poss due tc bsence of S. natans II a relatively sms quant- f S. natans types VIII a in these collec
The o ce of Rhizogeton fusifo A. latecarina!
Sargr mifolium and S. natans spectively, ma the c tances of absolute spec On these Ss 57
forms A, latecarinata was dominant on the only sample of S_. natans VIII examined, while R. fusiformis was dominant on
2 or 3 samples of S3, ramifolim. As a result of this, it is suggested that R. fusiformis and Clava sp., described by Burkenroad as a frequent dominant of Sargassum (S. rami-
folium), are the same. R. fusiformis has also been reported on the seagrass Dlplanthera wrightii at Seahorse Key, Flor- da (Joyce, 1961).
The dominant hydroid species and their relative fre quency on the Sargassum forms collected are presented in Table
2. Burkenroad suggested that dominance of hydroid species on specific Sargassum types may result from succession of epibionts rather than evolved dependence on that particular
Sargassum type. Interpretation of hydroid distributional patterns on the Sargassum thalli lends credence to this.
As a result, it is suggested that gross generalizations regarding strict specificity be avoided, although frequent associations are recognized as potential aids in field i~ dentifications and for suggestion of likely associations.
Species Interactions
Burkenroad (in Parr, 1939) concluded that the rate of growth of the hydroids, the growth rate of Sargassum, and competitive interactions of epibionts would determine dominance by hydroid species. This is exemplified by C. noliformis which was always dominant on S_, natans, due to the rapid growth rate of both forms. Aglaophenia, however, which 58
TABLE 2. The dominant hydroid species and their relative frequency for each Sargassum form collected.
no, of occurences per cent Sargassum Dominant hydroid(s) (hydroid-Sargassum) frequency
$. natans I Clytia noliformis 17-22 77.3%
II Clytia hemisphaerica 2-22 9.1%
II Obelia hyalina 3-22 13.6%
S. natans VIII Aglaophenia latecarinata 1-1 100%
S. natans IX Clytia noliformis 1-1 100% 1
S. fluitans III Aglaophenia latecarinata H H M 64.7%
VI Clytia noliformis 3-17 17.6%
11 Obelia hyalina 2-17 11.8%
11 Clytia hemisphaerica 1-17 5.9%
S. fluitans X Plumularia strictocarpa* 4-5 80.0%
It Aglaophenia latecarinata 1-5 20.0%
If Obelia hyalina* 3-5 60.0%
S. sp. C. noliformis* 2-7 28.6%
If Z. costata 1-7 14.3%
It P. margaretta 2-7 28.6%
ft C. hemisphaerica* 1-7 14.3%
II 0. hyalina 1-7 14.3%
II A. latecarinata 1-7 14.3%
S. ramifolium R. fusiformis 2-3 66. 7%
If 0. hyalina 1-3 33.3% 59
TABLE 2 (continued)
no. of occurences per cent Sargassum Dominant hydroid(s) (hydroid-Sargassum) frequency
S. filipendula 0. hyalina 1-4 25.0%
11 A. latecarinata 1-4 25.0%
11 C. sargassicola 1-4 25.0%
II P. strictocarpa 1-4 25.0%
P. polyceratium P. margaretta 1-4 25.0%
If C. pelagica 1-4 25.0%
M S . stookeyi 2-4 50.0%
S. pteropleuron A. latecarinata 2-4 50.0%
It S. inflata 2-4 50.0%
S. hystrix C. pelagica 1-3 33.3%
S. bermudense A. latecarinata 1-1 100%
*denotes shared dominance 60 can not keep pace on the fast growing £, natans, can dominate the slower growing S_. fluitans presumably because it is com petitively superior to the faster growing hydroid species.
Ryland (1974) indicated that the growth rate phenomenon suggested by Burkenroad appears to be true for natans where only C. noliformis colonizes the newest algal growth, spreading rapidly from below the frond tip. He hypothesizes that unhindered, the spread of C. noliformis is allowed because the production of tannins by actively growing regions of the thallus inhibits the development of surface microflora,
(Conover and Sieburth, 1964;uSieburth and Conover, 1965), a preequisite for the settlement of large epibionts. Studies by Kato et al. (1961, '1962, 1963) have also illustrated the effects of species interactions on the location and abundance of certain hydroid species. The hydrozoan, Bougianvillia sp. was shown to inactivate Clytia volubilis (Linnaeus) and and Orthopyxis platycarpa Agassiz when grown together
(Kato et ad., 1962). Also reactivation occurred with the removal of the Bougainvillia. Mechanisms for this interaction were not given.
Another final factor limiting the distribution of epiphytic
Hydrozoa suggested by Nishihira (1965, 1966, 1967a, 1967b,
1968a, 1968b, 1968c, 1968d) is that settling larvae have a clear preference for certain algal substrates. Phaeophytes appear particularly suitable as substrata for hydrozoan attach ment as indicated by the relatively large numbers of hydroids 61 which attached to them, and in particular to the Sargassacae.
These preferences have been shown by the relocation of algal types to different intertidal zones. In addition, experi ments by Nishihira (196 8a, 196 8b) on the effects of various algal extracts on Coryne uchidai Stechow (usually found on
Sargassum)showed that the chemical components of several
Sargassum spp. were significant in promoting hydroid larval settlement, while extracts from other algae proved to be either ineffective or detrimental to their settlement. APPENDIX 1. Station locations, Sargassum types present with associated hydroids their relative abundance and presence or absence or gonothecae. 3-S > s s Cr> CM G G .<■> o •H X) X 13 U U rH c/i U CO Q p O•H CO G tp 0 0 >i p 0 CM G G g O CD o 03 CO G g g G CP G G 0) CL) p B • O o *H MM 13 <—I f cn cn lO r^- CO i £ v c-- 00 CN •—i CN in o col 6|6|6|^'i l lu o pJtolo’l^ieh <|pJluiN|o*ic3l I oital C JicJlolpIjNla ro ++++++ I I + ++ + + + + + P M CO —1 CO £ P B c O 0 G CO G G G • •
•rM -rM x x p P CD - P P P U O O O O U fti G G g u C0 D> CD : •H X i — G G 1 -H P P G P P G G o O CO •rf x —!•H i— ! G G G HOG O *H 13 rM )M G CD p O p (0 O P G u •H rH CO w| I+ I I I X P p p £ P G G CM O O p O G G to co g • -H -H x X b 0 0 o g O G P DG CD CM 55 g CO •H X rM P £ £ o o o G c P G >1 G G Hg -H rM p P P O o 0 G G G G CD O •rM p B O o G o B >i P G CD r CD •rM •r| mm rM CN to! e M CO b O p 0 10 CM G I I o o e o b • •rM •rl X X * P O G G B CO MoC G CM o CM CD o O o U O U O O •rM r •rM*r| rM cn CN VO CN MM O LD rM in VO coj cn CN P f-r VO O £ oCn + I I I + + 1 1 1 + I I + I till I I I I I I CD o g g g g * * c 0 0 0 O cd • ♦ • • 0 CD * • • • 0 • • • 0 U g g g 'd g g g g g g g P g g g g g g g £ 0 0 0 0 0 0 0 p cd cd cd cd cd O cd cd 0 0 cd cd cd ft ft •H P ft •H •H f t ft p cn cn p cn p p in CN 10 r> CO in 0 on in CN r - rH rH o > g X X £ X M , *H H M cn H cn rH £ S cn O cn cn cd cn CD £ P £ £ P £ P cn cd •H cd cd •H cd •H cn P g p p £ P £ cd cd CO cd cd i-H cd 1— ( Cn £ p -£ f l 4-1 £ P p cd • • • I m m w t/5 CO w | w ) w ft ~ CN 1 0 g o * • . VO r-~ Cn co CN £ — O O in s s r - 1—1 10 p — CN in T5 Cd 2 O 0 CD 1-3 '— co £ co co •H£ P £ o cd o rH CN & a a cd CQ * cn •H i d cn TJ CD 10 £ p CD cd ft a co ft CN 10 < I CN in I CN in CN 63 Appendix 1 (continued). > P ? I d 53 fd ft tr> o r-x o T3 £ X» H r Q p CO E o ft co tn o o fd cd g HJ fd ro ro CM o oro ro ro 1—1 00 CM CM CM Q CO p H -P •H tp i—1 •r) ** P •rH A oo rH CD CO i p X — . g o o o o fd 01 G G fd fd G i i I I I + + 1 ■H p p P P O O E£ p o p fd 0) id o o •H i p p — fd id o o o o•o oo o i A + + + + + CO i—1 CM in ro i—i in t"* 1 O CM CD CD i to1 ui| i-H >3 ** p cr> CO *3 ltuiil f! ui w| Q( llfl ul fl ol lftl lu |o < lftl lo lu a olulffil ( (Q |d |w iN lu lft!d < olftluli^iNl *H P X X CO fd g o o £ £ CD ft td o -P P u fd rd cn 0 CD P u I o O m -H CM to o> CO r-' CM vD •<* CM to vO rH o CO O CM rH co o H M 3: O p •H •O rH (0 p fd G P G g I o o o o fd p td fd a CD G td 1 • • « • Hi— •H p P + g g g o O fd ft td o p p CO o •H x + fd td o IP G 65 ! •H -H P rH + g cn o 0 P O G + p p p P P £ o o o 0 o o CO fd g fd o o • -H 4-1 i— i o g fd c fd fd G 1 • H•H •H -p g o 0 ►. G G P P g 0 1 'O p p o g (d o o CD G tG fd G 1 *H MH •H •H iH TJ rH i X + + + + wl — g o dX fd fd fd o G ft G 2 CD • 1 ‘H •H X X td fd P u ft g CD CD CO g fd £ G o o HCD *H r -H -rH P T3 I™1 O' O rH CTi oo CM + + I + CM rH CO CO o o CM rH CM CM 00 cnl 00 CO 3= g g g g g g CO o X P O 0 G *H X X o fd tG ft fd o o p P CO g CD *H rH o o fd o o tp fd -H p p dG td ft (d p o o o CO *H H3 P •H I—I r— i P rH rH cn H H -p H p o o G cn fd cd fd fd P u fd 0 + 1 + I + -H *— X g a I fd G p 1 •H H•H •H P t— 1 g o o CO O g p O G P P g o o ft fd fd p O CO P o o Appendix 1 (continued). rH ^ — +j — R R '•*' !> d 3 cd Cn g o £ — CM 0! O cd rH •H Xi 05 Q p •o H3 C/1 0) cd Qc 0) m Cn fd 05 •H rH <4-1 rH -d* + + + + + + i—I 05j H ul wl ! ul<|p4*i w! l lw lu lu N H 4-> O £ o CD td G o u p £ -H Hr CD rH -H <0 1—1 cd p Cd >1 )CD d) u p u c •rH p -p cd dP cd cd P p c I •H r—1 no in H M H g -P -P P cd cd 05 O cd cd B G cd cd cd o G c o S. . O O r- -H P •H •H p CN CO co ro ro ro o ro o ro rH i—I CN ro o CN CN VO ro CN H S i—1 H M M 5 05 05 p c o O B G G o o G I I I I I I I I + • . S. .6 ■H H0) rH p -p cd CD td o o G P o cd . •iH rH -P P 66 p td o Ot td o o P o £ o . •H rG o -p o cd cd o f- g I P -P n o td O 05 O £ op ro u cd • . I < |o t u u t |o < m r- CN CO H O o H f 3 •H G P oo ro CO ■rl x: •H O ■& CN p H lnN Hu •H •H P o o od o o ro H’ rH i—1 M M H P P 1+ I I + + g g s g g g g g g s g d0fd 0 fd td P G dP fd fd fd G CO a o oo o o o S. G g fd P 4 p CO fd 04 fd P O P P o dfd fd o CO dg fd G G P G 67 *H rH rH in w) d o o o o o o o o o d P p P 04 O >4 P g 0 fd P CD dp fd O fd tn g g g g g g g O g g g O O O g O i i i i + i HrH •H P P CO fd fd 0 D fd O fd P U •H x: ►H fd G p P fd a fd o CO *H X3 ■c •H Of a) id P fd CO 53 g D •H p CO >i d fd P 0 o 5 . clln dl dl ulol l ld lo d iccldlcnl |. •H rH o o d 10 col p 04 CO fd P a G fd 0 fd o o o o g g g I i I I •H X! rH fd G >4 •rH p t p dPfd P td dP fd -1 G o o •H ** •H rH r*' C"- CM ro o o O CN ro CN 10 ro O o H H +i + H 5 col -P O g CO oo 5 O g g G O fd fd CO c G •H XJ rH fd >4 fd G p P td o o CO O o r- CM r- o m in in ro § CM r* o CN o H H ro •H H •H d o d p Appendix 1 (continued). .ft rH s a + ' J > o Cn G O j ^ ' CD ,G 'd tJ I rH g1 CO CO P %■ 3 Cn a, g Cn id O W id o O id CO CO P CD id G G G u a) p : in -P -p + CO Slflll | K | 0 [ t f l < tSllffilulKl w -P to id O id G o o s id CO o G id G I I + I j . S 4J o u G g id G G « •O I G •H ,G i i i o o •p - id id P P Cn Q) p id g g -H P CD id •H i—c did id o 0 CO oo o CO id p cn id CO rH i rG — id id G I* 1 -H - •P tid ft id P o o P p o CO •H -H i G — £ CO p 1 H-H •H •H G i •P E 1 — CO 4> P -P -P 4-> O id G g 13 U -P -P g O o O U id did id G CD P 1 O G •H £ 1? o o e g o o id id G G ft G Appendix 1 (continued). i P PI > — d 2 fd O & ft a H g Cn — i—i P cn Q ,£ •H A no no no nj CD ft c O £ to Cn td o c c o td: P cn cn £ g a ' •H •H XI +J O «H rH o p p p fj dj o j |d n |ftjc d col P g o g o g CQ CD o to £ £ £ ft P oto to a) E 0 CD P ft £ P 0 £ ft O CD • • •H •H p no p + I + o o o o tn nO o o ft to to P £ > o •H -H —1rH i— 1 to p to >i p a) P o P £ V o o •H in t" p oro ro CM o o 00 o CM cn rH CM r^- rH o o *3* HH tH ro ro H H o ci cl o cl col col co| col c/i| P co| P H H £ H -H HCD *H fd cn I+ I I £ £ £ cn O g p O £ t I ■H q tr0 >t g f0 P lo lo ■H rH >i £ fd | ■H P p p td o P ft p fd P CD f0 01 o P o I | <1 <1 | 69 O O O rH CM p" 00 CM rH ro ro o in CM P rH i— 1 o i— 1 00 H ro 3:- H H H H -H cn rH fd £ P p fC td g g o g td td £ P o td u CD • • • . -H P no "CM P" i rH i— 1 p cn’ S l fd P o td CD P O ft CD P O £ t+3 ft £ £ o I I + ft o cn £ >1 CD a L j • • •H P rH | o td o p ro CD P £ td -H .a ,c no nO P p ft W <0 cn P CD 1 > o p o CQ £ p £ o i—I ro i ro p" 00 r- ro CM o o in CM rH iH O o H H 3: H P — no ro cn 111 1 1 + £ £ ululoltol g 1 • o o •H 0 O P O O O 10 m »H r-H no I+ I + I CM d l c n l o o l Q l g oo g fd ft CD £ £ P g g o o o id o P CD cncn ft ft £ . . •H g p CO CD Appendix 1 (continued). > 3-S PI — -p - a Cn ft d s cd 6 iH G O 0) — 3 & b> 5 I—I CO Ul a - >i co o O o ft p o fd G S o o in r^> ro in rH o cn CM CN rH ro co rH o o o col co •P H H & H ) o T) fd G ul ulcsQtoIl j ld (d < •p e o o g a o 1 -p o e O g i 1 dcd cd p p p )0)0) ,C p I T3 cnl B 0 CO ft I • <1 P p cd CD I l|x||t -<|p«|oIn|o ] d dl<|jxT|u|Nt 70 O o •rH •H fH »P CN ro CN -C r- 00 ■sr I—I 'd4 CO o i—I H CO CO rH co o ro O + cnl •P H H IH & H M >1 0 e O B o o -p g O u o u o PI -p B o o o G 1 + 1 • -p S u G • •rH .c «—I -P oil B o >i fd G q td c (0 ft • . o o •H in m M-f i ro ID 00 o in t"~ rH in H M CO I—I o o CN col i—i co o O ■P H & M H M 'd 1 — fd 10 3 G § I I + I + I o o uo 8 • O • • 8 *. 1 ■8 uI •rH -rH . CO ro U*l I I + 1 1 1 + 1 1 + 1 + + 1 1 I I 0) # • • » o E B B E E c o o O 0 o § G u o o • .• • • u CD ••• » • o o *o B B B fi B P S B E B B c p p P OO O o o -p G o o 0 0 o p p 8 P 0 0 O o o 13 u o o p 13 o 13 o u o o 13 Si G G G G G c G cd GG O cd G G G G O G O •H ft P f t ft rH *H f t •H 03 P p G p 03 03 P O P P P m •H <1> Cd G G H •H G o CD G CD u cd o •H U B E U G •H G U G G *H G p cd cd G o P O G p G P O O 03 03 G 0 O G o pi O -P G f t p G P P O G O P •H ■H 03 ft P *H ft p cd e P cd *H 0) o O o G p •H ip O Cn rH G 03 o Cn 03 13 P p •H P iH ■H CD *H P *H i— 1 •H -H G ■H Cn *H •H G •H >1 03 G i— 1 03 G g PP P 03 i— 1 G «H P rH B P B P tH B G O cd O O rH 53 PG P O O Sn O P CD G G CD P CD CD O G G o G G 03 «—1 03 , 0 G G G 03 ft G 03 G 03 ft G p IlN la l u I n I o I o I pJI o o Cn o ro C—' O O OS: cn cn G'-' r- r-~ o o ro ro -P-— O O G S O O G~ ro ro CD rH 00 ft •—i rH S & ui ro ro r-* !"• CD P H H G H M Q W H CD VD i—1 rH 71 Appendix 1 (continued). r—1 > P PI ~ E P d 52 fd o 0 O O Cn B — 04 G G c 0 h o & a — P — 03 03 rH 03 Q & P 03 O p o o ui Oi I ■rl -H i o — C Ul e p o 0 O G o • 1 I -M P n E a) u g £ e E £ G boo o o d o u o 0 • o o dJ £ £ ft £ g eg £ G o o p p p d 8 8 O P P o o o o o.uoo o o o o o ft tJ o »o. o o. o o o o 5 G G G G G d d d d d d o d d u o f t CL •ft P p •ft •ft d o ft ft d d d to ft to ft 0 p o d 0 o G G •ft 0 -ft 0 T3 p d •H d o d •H •ft CO •ft £ d £ d -ft 0 o to to G o rG ft ft to •ft d d ft ft G d ft d G d u -H CO d p CL rU d •ft i—1 G G d O CL P o G 04 P O to d B • *ft •ft u d A g rH d G o CO G o ift •ft •ft o P CO d f t n cn d •H tn CL •ft •ft ■ft 0 •ft Cn rH i—1 0 •ft ■ft p -ft f t •ft P >1 ft » • i—i g ft d ft £ i—1 P £ * G d d P r f t £ to f t d £ to G d f t f t a) 3 d -H P 0 d G CL ft >1 d o 0 o o 0 O g to CO Oi G .0) 'O . w G O t—I rG to P G rG r f t G G o G G G o f t ■ vo CN CO CN in £ CN ft f t CO O > £ H (ft G (ft (ft -ft (ft H P c d H 0 0 H p ft G G CO 0 0 d d 0 0 o G P P G d > i d •ft •rH d tn f t p GG P ft o d t—1 f t d d CL G P p G Ul s_ s W S s Oc CO v0 cn o • • « f t LO f t CN CN CN CN cn O f t VD Cn. CN co O m o O o O CO o o o S? r- CO CO r ^ o o r f t cn ro CO o o O o o O cn cn cn o T5 CN CN CN CO CO CO r~- r» r - a cn 0 H H H VO c P H M (ft H H X 0 Qd H &CL, O f t f t f t CN CN CN 73 Appendix 1 (continued). H > X E-f 0( 0( — Cn o g d s 'd CN | w I + CO I rH rtf fd c 3 O O O O T3 rH o ■K col X g g g g a 'duo col p X X CO o* fd o o o gee g fd u Cn td 0) I I I I I TI o I n I ph I *d CN col ps I II I I o u u I +> pk c o I o O -H o u o o o •d rH CN m X ID cn ■sr r- in o rH CN o o cn o CN + + + I + + M o CO*I O | 5C I U X < 8 0-0 0.0 0E 0 co fd >s fd fd c c c B g g g g >i c CD a x » fd o co IH & C . . ■ H X *H X -H H 01H P o u M g CO h Q) X O O C o d x fd a> I n I •H u fd u J O c o tn I I + + + T I + <1) O G ■K * id. . Q) • • 'd e e g g O% o o in ro rH co i—I o > M H ‘ W cn to fdg s in -p -p fd fd fd cn G G u <0 in w | cnl e& —o cu o sr CN B — CN CN o Cn m CN G O O o CN o m +> ^-s o o (d 53 o •H G\ (T\ Td 0 lO ID g 4J 75 PLATE I Figure 1. Rhizogeton fusiformis Figure 2. Cladocoryne pelagica, hydranth wtih gonophores Figure 3. Cladocoryne pelagica, tentacle Figure 4. Coryne sp*, with gonophore Figure 5. Zanclea costata, with gonophore Figure 6. Garveia humilis, with gonophores 76 Plate I 0.50mm FIG. 6 1.0 mm o {/ qQ' [O | ( soi & CQ Q-rf- UJ 0.50 mm 0.50 mm 0.50 mm FIG. 5 FIG. 4 0.50 mm FIG. 3 PLATE !ri Figure 7. Pennaria disticha, hydranth with medus, Figure 8. Halecium nahum Figure 9. Halecium nanum, gonotheca Figure 10. Halecium sp. A Figure 11. Halecium sp. A, gonotheca Figure 12. Halecium sp. B, hydranth Figure 13. Halecium sp. B, colony, gonotheca 77 Plate II FIG. 8 0.50 mm FIG. 7 0.50 mm FIG. 10 0.50 mm 0.50 mm FIG. 9 FIG. 12 0.50mm 0.50 mm FIG. 13 FIG. 11 0.50 mm PLATE :r n Figure 14. Clytia cylindrica Figure 15. Clytia 'cylindrical gonotheca Figure 16. Clytia fragilis Figure 17. Clytia hemisphaerica Figure 18. Clytia hemisphaerica, gonotheca Figure 19. Clytia noliformis Figure 20. Clytia noliformis, gonotheca 78 Plate III 0.50 mm 0.50 mm FIG. 16 FIG. 14 FIG. 15 0.50mm 0.50mm 0.50mm FIG. 17 FIG. 19 0.25mm FIG. 20 ?1. Clytia is . 2. Campat aargassicol. ! 3. Cairtpan Bargassicol heca •: 4 • Obelia i f colony v: chec a >5. Obelia a, hydrothec ; 6. Cu'spic ail i s 79 Plate IV 0.50 mm 0.50 mm FIG. 24 FIG. 21 0.35 mm 0.20 mm FIG. 25 FIG. 26 0.50mm 0.50mm FIG. 22 FIG. 23 PLATE V r- CM Figure • Scandia mutab!11s CM 00 Figure • Dynamena mayeri Figure 29. Dynamena quadridentat a 80 Plate V FIG. 28 PLATE VI Figure 30. Sertularia inflata Figure 31. Sertularia inflata Figure 32. Sertularia stookeyi Figure 33. Sertularia stookeyi Figure 34. Sertularella parvula 81 Plate VI 1.0 mm FIG. 30 0.25mm FIG. 31 0.50 mm 0.25 0.25mm FIG. 34 FIG. 32 FIG. 33 PLATE VII Figure 35. Antennella secundaria Figure 36. Antenneila secundaria Figure 37. Halopteris diaphena, hydrocaulus Figure 38. Halopteris diaphana, hydrocladium 82 Plate VII l0.25mm FIG. 37 FIG. 35 FIG. 36 0.50 mm FIG. 38 0.50mm PLATE VIII Figure 39. Plumularia margaretta Figure* 40. Plumularia margaretta Figure 41. Plumularia strictocarpa 83 Plate VIII O .50p * mm 0.25 mm FIG. 39 FIG. 40 FIG. 41 0.25 mm PLATE ;IX Figure 42. Plumularia strictocarpa Figure 43. Plumularia strictocarpa, gonotheca Figure 46. Aglaophenia Tatecarinata Figure 47. Ag1aophe ni a latecarinata. hydrotheca Figure 48. Aglaophenia latecarinata corbula 84 Plate IX FIG. 42 0.25mm 0.25mm FIG. 47 FIG. 46 10 mm FIG. 48 PLATE X Figure 44. Plumularia sp. Figure 45. Plumularia sp. hydrocladium 85 Plate X 0.25 mm FIG. 44 ■&5ZH 0.25 mm FIG. 45 86 LITERATURE CITED Adams, J. 1960. A contribution to the biology and post larval development of the sargassum fish, Histrlo histrio Linnaeus, with a discussion of the sargassum complex. Bull. Mar. Sci. Gulf. Caribb. 10: 55-82. Agassiz, A. 1865. North American Acalephae, Mem. Mus. Comp. Zool. Harvard 2(1): 234 p. Agassiz, L. 1862. Contributions to the natural history of the United States of America. Vol. 4. Little, Brown, and Co., Boston, 380 p. Allman, G. J. 1871, 1872. A monograph of the gymnoblastic or tubularian hydroids. Ray Society, London. 450 p. Allman, G. J. 1877. Reports^on the Hydroida collected during the exploration of the Gulf Stream by L. F. de-Pourtales. Mem. Mus. Comp. Zool. Harvard 5 (2): 1-66. Allwein, J. 1967. North American hydromedusae from Beaufort, North Carolina. Vidensk. Meddr. Dansk Naturh. Foren. 130: 117-136. Ayers, W. C. 1854* Description of a new species of polyp Globiceps tiarella Ayres. Proc. Boston Soc. Natur. Hist. 4: 19 3-194. Bennitt, R. 19 22. Additions to the hydroid fauna of the Bermudas. Proc. Amer. Acad. Arts. Sci. 57: 239-259. Brinckmann-Voss, A. 1968. Anthomedusae/Athecatae (Hydrozoa, Cnidaria)of the Mediterranean. Part I. Capitata, Fauna & Flora Del Golfo di Napoli. 39 Monografia: 96 p. Burkenroad, M. D. 19 39. Hydroids on pelagic sargassum In: A. E. Parr, Quantitative observations on the pelagic sargassum vegetation of the western North Atlantic. Bull. Bingham Oceanogr. Coll. 6(7): 23-35. 87 Calder, D. R. and M. L. Brehmer. 1967. Seasonal occurrence of epifauna on test panels in Hampton Roads, Virginia. Int. J. Oceanol. Limnol. 1(3): 149-164. Calder, D. R. 1970. Thecate hydroids from the shelf waters of northern Canada. J. Fish. Res. Bd. Canada. 27: 1501-1547. Calder, D. R. 19 71. Hydroids and hydromedusae of Southern Chesapeake Bay. V a . Inst. Mar. Sci., Spec. Pap. Mar. Sci. 1. 125 p. Calder, D. R. "1972a. Cnidaria of the Chesapeake: Bay. Chesapeake Sci. 13 suppl. S-100-S102. Calder, D. R. 1972b. Some athecate hydroids from the shelf - waters of northern Canada. J. Fish. Res. Bd. Canada 29: 217-228. Clarke, S. F. 1879. Report on the Hydroida collected during the exploration of the Gulf Stream and Gulf of Mexico by Alexander Agassiz, 1877-78. Bull. Mus. Comp. Zool. Harvard 5: 2 39-252. 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