Striatodoma Dorothea (Cheilostomatida : Tessaradomidae), A New Genus And Species Of Bryozoan From Deep Water Off California

6 Pages·1999·2.9 MB·

by  J E Winston

PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON
112(2):313-318. 1999.
Striatodoma dorothea (Cheilostomatida: Tessaradomidae), a new
genus and species of bryozoan from deep water off California
Judith E. Winston and Stace E. Beaulieu
(JEW) Virginia Museum of Natural History, Martinsville, Virginia 24112, U.S.A.;
(SEB) Marine Biology Research Division, Scripps Institution of Oceanography,
La Jolla, California 92093-0202, U.S.A.
(Current address) Applied Ocean Physics and Engineering Department,
Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, U.S.A.
—
Abstract Striatodoma dorothea, a new genus and species of cheilostomate
bryozoan, is described from material found attached to hexactinellid sponges
m
and pogonophoran tubes at an abyssal station (4100 depth) off central Cal-
ifornia. Members of this new genus can be distinguished from other members
of the family Tessaradomidae by the presence of biserial, rather than quadris-
erial branches, and a peristomial sinus, rather than an enclosed spiramen. Two
&
other Pacific species, Diplonotos striatum Canu Bassler, 1930, and Tessar-
adoma bifax Cheetham, 1972, are transferred to Striatodoma.
Although bryozoans have been identified lostome which we name and describe be-
from deep-sea stations down to 8300 m, re- low.
views by Schopf (1969) and Hayward
(1981) have shown that only a tiny portion Tessaradomidae Jullien, 1903
of the deep ocean floor has been sampled Striatodoma, new genus
for the group. Nothing is known of the
—
deep-sea bryozoan fauna of the eastern Pa- Diagnosis. Tessaradomidae character-
cific with the exception of three species ized by subcylindrical, proximally thick-
found at two stations in the eastern Pacific ened branches with two series of zooids,
between Acapulco and Panama during the longitudinally striated calcification, a spi-
Galathea Expedition (Hayward 1981). Re- ramen in close association with zooid peri-
cently, as part of a study by Beaulieu stome, rows of marginal pores, some of
(1998) of hard substrate epifauna at abyssal them replaced by oval avicularia, and a
depths off California, an attempt was made subglobular imperforate ovicell. Striatodo-
to identify all taxa attached to biogenic ma differs from Tessaradoma in possessing
structures that protruded from the soft sed- branches made up of two, rather than four
iment of the sea floor. Individual stalks of series of zooids, and in confluence of the
the hexactinellid sponge Hyalonema sp. and spiramen with a —peristomial sinus.
individual tubes of the pogonophoran Uni- Type species. Striatodoma dorothea,
brachium sp. were sampled in tube cores new species, by present designation.—
m
using the submersible Alvin at 4100 Additional species ofStriatodoma. Tes-
depth. Two of the approximately 140 spe- saradoma bifax Cheetham, 1972 and Di-
cies found attached to the sponge stalks and plonotos striatum Canu & Bassler, 1930.
—
pogonophoran tubes were bryozoans. One Etymology. The first part of the genus
is a ctenostome, Arachnidium hippothooi- name is from the Latin, striatus = fur-
des Hincks, 1862. The other is an undes- rowed, channeled, descriptive of the striated
cribed genus and species of deep-sea chei- appearance of colony walls. The second
314 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON
part, doma, is derived from the Greek brevissima from the Tasman Sea, but Gor-
8a)fxa, 8a)|jLaTo^, house, roof, to parallel the don (1989), who recorded T. brevissima
other genus name in the family, Tessara- from additional deep water localities off
doma. Gend—er neuter. New Zealand, placed the species in the ge-
Remarks. ^During the last hundred years nus Galeopsis (family CeUeporidae) on the
seven Uving and fossil species of deep wa- basis of the following characters: paired av-
ter cheilostomes have been described and icularia in close association with peristome
placed in the family Tessaradomidae Jul- and sinus, and an ovicell with a central tab-
lien, 1903, and genus Tessaradoma Nor- ulate or fenestrate area and labellum. Two
man 1869, type species Onchopora borealis South African species, Tessaradoma bispi-
Busk, 1860. Jullien defined the family as ramina and Tessaradoma circella, de-
having erect or encrusting colonies and zo- scribed by Hayward & Cook (1979), and
oids, a tubular peristome with a tubuHform the Indonesian species Tessaradoma bipa-
spiramen opening into its base, and with a tens, described by Harmer (1957) also seem
small, spherical, imperforate ovicell, also to belong in this group.
opening into the peristome above the zo- In contrast, the new Pacific species de-
oidal operculum. The genus Tessaradoma scribed below, as weU as two other Pacific
has a colony form consisting of erect, un- species, the Eocene Tessaradoma bifax
jointed cyHndrical branches arising from an from the smaU western Pacific Island of
encrusting base, zooids with a projecting Tonga (Cheetham 1972), and the Recent
peristome and prominent spiramen, imper- Tessaradoma striatum from the Galapagos
&
forate ovicells obscured by increasing cal- (Canu Bassler 1930), differ from them in
cification, and adventitious avicularia (Hay- the furrowed appearance offrontal wall cal-
&
ward Ryland 1979). The type species, cification, the subspherical imperforate ovi-
Tessaradoma boreale, has a Recent distri- cell and the association of the spiramen
bution in both the North and South Atlantic with the peristomial sinus. These Pacific
and is also known from Neogene fossil lo- species appear to be related to Tessarado-
caUties in western Europe and the Mediter- ma, but their shared features indicate they
ranean (Cheetham 1972, Lagaaij & Cook should be grouped with the new species de-
1973). Its colonies are erect, rigid, and scribed below in a new genus, Striatodoma.
spreading, with quadriserial branches con- The Eocene Tessaradoma bifax described
sisting of elongate oval zooids, arranged by Cheetham (1972) from Tonga, is very
back to back in alternating pairs. The zooid similar in morphology to Striatodoma do-
primary orifice is concealed by a tubular rothea, with biserial branches, tubular peri-
peristome with a spiramen tube near its stome, and with lateral pores and avicularia
base, its opening projecting from the zooid making a sinuate double trail along the
frontal surface about one third of the way sides of branches. In this species, however,
down the frontal waU. Wall calcification is the sinus (at least in the fragmentary ma-
granular, becoming striated around the con- terial available) does not become calcified
spicuous marginal pores. Oval adventitious into a tube. In addition, its oviceU is not as
avicularia are also developed in the mar- prominent as that of S. dorothea, appearing
gins, particularly lateral to the spiramen. only as a sUght enlargement of the peri-
The ovicell is small, smooth, imperforate, stome of the maternal zooid, and a swelling
subspherical (slightly broader than long), of the frontal shield of the distal zooid. The
and though conspicuous in young zooids Recent Diplonotos striatum collected from
becomes increasingly immersed in calcifi- the Galapagos at 1251 m depth (Canu &
&
cation as zooids age (Hayward Ryland Bassler 1930) also belongs in this group.
1979). Based on his studies of syntype material,
Hayward (1981) described Tessaradoma Cheetham (1972) transferred that species to
VOLUME NUMBER
112, 2 315
Fig. 1. Striatodoma dorothea new species. All illustrations fromportions ofholotype colony. CASIZ 113579,
m
attached to pogonophoran tube collected 4100 depth onAlvin Dive 2828 at 34°42'N, 123°00'W, offCalifornia.
(A) Largest colony fragment showing colony form and branching pattern [scale = 2 cm]. (B) Zooid morphology
[from left to right] autozooids in side and front view; ovicelled zooids in front and side view [scale bar = 0.6
mm]. (C) Closeup ofperistome, showing spiramen sinus [scale bar =150 ixm]. (D) Closeup ofmature ovicelled
zooids, showing constricted peristome and completely enclosed sinus [scale bar = 0.270 mm]. (E) Closeup of
lateral avicularium, showing diagonally tilted rostrum and calcified pivotal hinges [scale bar =100 jxm].
Tessaradoma on the basis of its similarity sinus in S. striatum may become completely
to T. bifax, remarking that, contrary to enclosed to form a tube.
Canu and Bassler's original description, the
primary orifice does lie at the base of a Striatodoma dorothea new species
peristomial shaft, but that shaft is almost Fig. 1
completely immersed in the thickened fron-
—
tal shield. Its chief difference from the other Holotype. California Academy of Sci-
two species lies in the extreme development ences, CASIZ 113579, attached to pogo-
of frontal wall calcification, in which stri- nophoran tube collected as stalk no. 3
ation becomes rugosity and external zooid (Beaulieu 1998) at 34°42'N, 123°00'W,
m
boundaries are lost. The positions of lateral 4100 depth, 17 Sep 1994.
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avicularia and pores may still be faintly dis- Paratypes. Virginia Museum ofNatural
cerned, however, and match the pattern in History 567; from stalk 4, —4100 m,
the other two species. Like S. dorothea, the PULSE 22 Cruise, Chief Scientist Kenneth
316 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON
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Table 1. Measurements (in mm) of holotype and paratype specimens of Striatodoma dorothea.
Character Range Mean SD n
Zooid Length 0.364-0.501 0.444 0.038 12
Zooid Width 0.191-0.273 0.231 0.027 12
Orifice Length (autozooid) 0.073-0.100 0.085 0.009 12
Orifice Width (autozooid) 0.091-0.109 0.—102 0.—008 12
Orifice Length (ovicelled zooid) 0.073 — — 2
Orifice Width (ovicelled zooid) 0.100 2
Ovicell Length 0.109-0.155 0.134 0.016 6
Ovicell Width 0.182-0.210 0.196 0.011 6
Avicularia Length 0.036-0.055 0.044 0.007 11
Avicularia Width 0.027-0.046 0.036 0.004 11
Branch Width (Distal end) 0.291-0.337 0.301 0.025 12
Branch Width (Basal end) 0.364-0.728 0.558 0.103 9
L. Smith, Jr., Scripps Institution of Ocean- ran tubes by an encrusting base. Zooids
ography, Alvin Dive 2828, 17 Sep 1994. elongate, rectangular, growing back to back
Water temperature 1.2°C, 34°42'N, in two alternating longitudinal series (Fig.
123°00'W; CASIZ 113580, stalk 37, IB). Frontal wall convex, with faint longi-
34°56'N, 123°07'W, 4100 m, PULSE 24 tudinal striations, most of its surface im-
FVGR, 16 Feb 1995; CASIZ 113581, stalk perforate, but with a row of small oval
33, 34°42'N, 123°00'W, 4100 m, PULSE pores just inside zooid lateral margins. Pri-
25, Dive 2920, 30 Apr 1995; CASIZ mary orifice transversely oval, surrounded
113582, stalk 12, 34°42'N, 123°00'W, 4100 by a short peristome (Fig. IC). No out-
m, PULSE 22, Dive 2834, 23 Sep 1994; wardly visible spiramen; instead, the peri-
collector for al—l, Stace Beaulieu. stome of young zooids has a proximal si-
Etymology. dorothea, the Latinized nus, which is encircled by calcification as
spelling of Dorothy, used as a noun in ap- the zooid ages, becoming increasingly tu-
position. The species is named in honor of bular and projecting. Ovicells are smoothly
Dorothy E Soule, in recognition of her el- calcified and globular, reaching the height
egant studies of Pacific bryozoans and of of the peristome opening, which becomes
her active stewardship of California marine slightly narrowed in fertile zooids (Fig.
environments.— ID). About one pore per zooid is replaced
Diagnosis. Characterized by subcy- by an oval adventitious avicularium, about
Hndrical branches made up of two series of 50 |ULm in length. In side view the sinuate
rectangular zooids, with longitudinally stri- double track of pores and avicularia is dis-
ated calcification, rows of marginal pores, tinctive (Fig. IE, B). In basal regions ofthe
with occasional pores replaced by oval av- colony zooid openings are calcified over
icularia, short peristome with spiramen en- and branches become thickened. Some of
closed in proximal peristomial sinus, and the avicularia and pores are calcified over
relatively prominent ovicell. also. Branch thickness (the depth of two
—
mm
Description. Colony erect, rigidly cal- back to back zooids) averages 0.301 in
cified, unjointed, broadly branching in a zooids near the growing edge of branches
planar fashion, up to several cm in size, the and 0.558 mm in zooids near the colony
two biggest branch fragments of the largest base. Zooid measurements are summarized
specimen found (the holotype), measuring in Table 1. —
3 cm h X 7 cm w and 5 cm h X 5 cm w, Distribution and ecology. The species
respectively (Fig. lA). Attached to stalks of was observed and/or collected at 4060-
m
deep water glass sponges and pogonopho- 4100 depths off California, between lat-
VOLUME 112, NUMBER 2 317
itudes 34°38' and 34°56'N and longitudes
122°59' and 123°15'W. General area: 220
km west of Point Conception, CA. Beaulieu a
(1998) collected a total of 35 tube core ii >
5
samples at the abyssal station and found s
G
—
seven colonies of S. dorothea (one colony c >^. ca
per substrate; Table 2). The species was at- §'-I -«S
tached to pogonophoran tubes, the basal ^
•S
spicules of Hyalonema sp., and to other or- S -B
ganisms that were attached to the host sub- a &
strate. The branches of S. dorothea also o -o
—
provided substrate on which other species U
•--a
attached (Table 2). (c«U O 'o
l-l
In order to determine the abundance of 2 3
S. dorothea at the abyssal station, all colo- £ "o^ a!i Ti -a^
"c -I c
nies large enough to identify with certainty 5 e _o
2 o "o
were enumerated in photographic transects o
>^
of the sea floor (procedures described in dj o O X5 Xc)
We
Beaulieu 1998). photographed approx- ^1
o
imately 9 km of the sea floor (total of seven 3 ^
(U (U
transects) in which we encountered 55 col- <DO ** O Z O> Zo Zo
onies of S. dorothea. Of these, 53 were at-
tached to dead Hyalonema spicules, one to
a pogonophoran tube, and one to an un-
identified structure. The encrusting bases of oo
most of the colonies were attached at the X3) X3I
middle of the host substrate, elevating the 0 -i-i
^^
colonies about 10 cm above the sea floor. "w^ diy5
Xi
Density estimates (no. colonies per unit •2
U. c/3 r~^
caroemapuotfesreaprfloogorr)amweDreIScaTlAcuNlCatEed(uLsaiankgetheet o -caa X^3d)^ X3) 3 1^^.^S3
al. 1994). Mean density estimates for the cc3 <^ Ccd '«3a "1S "e^x
3 a CQ 3
individual transects ranged between 3 and X3
t8hecoblioongieensipcerstr1u0c0t0urems^.enOunmleyraatbeodutin2%phoo-f § "CcJIOs7-K^^--^S (c50 n1-3; nT-3; -5?K<i4j^ •7u3-3 ^.si^:^
o cu 0, c c ^ c/5 "t:
tographic transects appeared to be colo-
nized by S. dorothea. However, 20% of the ^
structures collected from the sea floor had
S. dorothea attached; therefore, the density
estimates from the photographic transects c c
maDyisbceusasnioonr.d—erToefsmsaagrnaidtoumdiedslobwe.long to w-J-. ;7-i x^oao;. XOaouI 31c^ <cc^s ^Q a^ Q
c c o
the fauna of the outer continental shelf and o o o 3^ 3 3 5 >3 O 73
slope. The 4100 m depth recorded for S. "o 0o- CoU a: 5>:^ :>i:! 3>:. :'i^;. E'^ '^5
o
dorothea in this study is the deepest re- c/3 'iJ
corded, but it is not much deeper than the a ^
m (N
3700 recorded for T. boreale. However,
T. boreale is found in much shallower wa- 3H (N r<^ Tf in ^ t^ o .
m
ter in the Arctic (70 depth), and Cheet-
—
318 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON
—
ham (1972) suggested that distribution of of the Galapagos Islands. Proceedings of the
such deep-sea species may be temperature U.S. National Museum 76, Art. 13:1-78.
Cheetham, A. H. 1972. Cheilostome Bryozoa of Late
controlled, limited to water temperatures —
Eocene Age from Eua, Tonga. U.S. Geologi-
between 2° and 13° C. This paper and Beau- cal Survey Professional Paper 640-E:l-26.
lieu (1998) provide a glimpse of how erect Gordon, D. P. 1989. The marine fauna of New Zea-
bryozoans with an attached base may sur- land: Bryozoa: Gymnolaemata (Cheilostomida
vive on the muddy deep sea floor. But as Ascophorina) from the weste—rn South Island
continental shelf and slope. New Zealand
yet, these species are known only from a
Oceanographic Institute Memoir 97:1-158.
few broken fragments, collected at widely Harmer, S. F. 1957. The Polyzoa of the Siboga Expe-
scattered localities by various expeditions. dition, part 4, Cheilostomata Ascophora II.
Better understanding of their ecology as Leyden, Siboga Expedition Reports, 28d:641-
1147.
well as clarification of their relationships
with shallow water species must await the Hayward, P. J. 1981.—The Cheilostomata (Bryozoa) of
the deep sea. Galathea Report 15:21-68.
kinds of collections that can provide mate- , & R L. Cook 1979. The South African Mu-
rial adequate for the detailed anatomic seumis Meiring Naude Cruises, part 9. Bry-
—
study necessary for phylogenetic analysis. ozoa. Annals of the South African Museum
79:43-130.
&
Acknowledgments , J. S. Ryland. 1979, British Ascophoran
Bryozoans. London, Academic Press, 312 pp.
We would like to thank K. Smith and the Hincks, T 1862. A catalogue ofthe—zoophytes ofsouth
Devon and south Cornwall. Annals and Mag-
pilots of Alvin for making the collections azine of Natural History, series 3, 9:467-475.
and in situ observations possible. S. Beau- Jullien, J. 1903. Bryozoaires prove—nant des campagnes
lieu was supported by a National Defense de I'Hirondelle (1886-88). Resultats des cam-
and Engineering Grant and by NSF grant pagnes scientifiques accompli par le Prince Al-
OCE92-17334Wto K. Smith. We are also in- Laake,bJe.rtS.I,,S2.3:T1-B1u2c0k.land, D. R. Anderson, & K. P
debted to Dr. C. Banta (American Uni- Bumham. 1994. DISTANCE User's Guide V2.1
versity) and Dr. A. H. Cheetham (National Colorado Cooperative Fish and Wildlife Re-
Museum of Natural History) for their help- search Unit, Colorado State University, Fort
ful reviews of the manuscript. Collins, Colorado, 84 pp.
Lagaaij, R., & P L. Cook. 1973. Some Tertiary to Re-
cent Bryozoa. Pp. 489-498 in A. Hallam, ed..
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—
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—
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