Urticina Mcpeaki, A New Species Of Sea Anemone (Anthozoa : Actiniaria : Actiniidae) From The North American Pacific Coast

9 Pages·1999·4.4 MB·

by  J S Hauswaldt

PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON
112(4):652-660. 1999.
Urticina mcpeaki, a new species of sea anemone
(Anthozoa: Actiniaria: Actiniidae)
from the North American Pacific coast
J. Susanne Hauswaldt and Katherine E. Pearson
The University of Kansas Natural History Museum and Biodiversity Research Center and
Department of Ecology and Evolutionary Biology, The University of Kansas,
Lawrence, Kansas 66045, U.S.A.
—
Abstract. Urticina mcpeaki, a new species of sea anemone, is described
based on specimens collected from the Coronados Islands, Baja California del
Norte, Mexico; Santa Cruz and Anacapa Islands, Channel Islands, CaUfomia;
and Point Loma, California. Mesenteries and tentacles of the new species are
arranged hexamerously, rather than decamerously as is typical for other species
of Urticina. The new species is distinguished externally from other species in
the genus by a radial banding pattern on the oral disc, longitudinal striping on
the tentacles, and typically debris-covered adhesive verrucae on a bright-red
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column. include the first detailed description of the two morphologically
different types of microbasic p-mastigophores in the mesenterial filaments. Ad-
ditionally, size ranges of holotrichs in the tentacle tips are given for the first
time for a species in the genus Urticina.
Urticina Ehrenberg, 1834 is the most Northwest Pacific and on both sides of the
speciose genus of sea anemones on the Pa- North Atlantic. Though originally applied
cific coast of North America. Gotshall to North Atlantic species, the names U. cor-
(1994) recognized five species: Urticina iacea, U. crassicomis, and U. lofotensis are
Columbiana Verrill, 1922; U. coriacea (Cu- applied to Northeast Pacific species sensu
vier, 1798); U. crassicomis (Miiller, 1776); Hand (1955).
U. lofotensis (Danielssen, 1890); and U. External characters that have been used
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piscivora (Sebens Laakso, 1977). Sebens for distinguishing species in the genus Ur-
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Laakso (1977) recognized the same five ticina are color pattern and the presence and
species under the generic name Tealia nature of verrucae on the column (Cutress
Gosse, 1858, a junior synonym of Urticina 1949, Hand 1955, Sebens & Laakso 1977,
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(Williams in Manuel, 1981). In addition to Gotshall 1994, Zamponi Acuna 1996).
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these species, Zamponi Acuna (1996) re- Internal characters include size and distri-
ported Urticina asiatica (Averincev, 1967) bution of cnidae, number and arrangement
and U. tuberculata (Cocks, 1851) from of mesenteries, and distribution of fertile
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Barkley Sound, British Columbia, Canada. mesenteries (Hand 1955, Sebens Laakso
On the west coast of North America, the 1977, Zamponi & Acuna 1996).
genus Urticina ranges from Alaska to Baja
California. Within this range, animals occur Materials and Methods
either in the subtidal or in both the intertidal
and subtidal zones (Cutress 1949, Hand Divers collected nine animals in Septem-
1955, Sebens & Laakso 1977, Gotshall ber 1995 at 25 m from 1.85 km southeast
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1994, Zamponi Acuiia 1996). Sea anem- ofthe tip of South Coronado Island, the Co-
ones in the genus Urticina also occur in the ronados Islands, Baja California del Norte,
VOLUME 112, NUMBER 4 653
Mexico. Ten animals were collected in May smaller than other species in genus found
1997 from Point Loma, San Diego, Cali- in Northeast Pacific; not larger than 5-6 cm
fornia at 15 m. Animals were held in tanks pedal disc diameter when expanded. Height
for observation before relaxation with mag- generally not greater than 3-4 cm; oral disc
nesium sulfate and fixation with 10% for- diameter when expanded similar to pedal
malin. Five museum specimens from the disc diameter. No cinclides present.
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California Academy of Sciences Depart- Tentacles. Long and slender when ex-
ment of Invertebrate Zoology and Geology panded, short and blunt with longitudinal
(CASIZ) were also examined: CASIZ furrows when contracted. Arrangement
61487 (two specimens) and 61488 (one hexamerous with up to 5 cycles; in most
specimen) from Santa Cruz Island, Channel specimens fifth cycle incomplete. Number
Islands, California, and CASIZ 61491 (two of tentacles 68-93. Base color of tentacles
specimens) from Anacapa Island, Channel in most individuals red; in some pink, tan,
Islands, California. or brown. Each tentacle encircled with
Undischarged cnidae capsules from the light-colored band at base. Longitudinal
column and structures at the margin, the ac- stripe extends upward from band at base 1/
tinopharynx, mesenterial filaments, and the 2-2/3 length of tentacle on aboral side (Fig.
tips and bases of the outer and inner ten- lA), then broadens, creating chevron shape
tacles were measured from squash prepa- on oral side (Fig. IB). In most individuals
rations at lOOOX magnification. Cnidae no- stripe white; other colors such as orange
menclature follows Mariscal (1974). Dis- may occur. Bases of tentacles outlined by
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play of cnidae data follows Dunn, Chia, dark red bands corresponding to mesenter-
Levine (1980). Histological sections 8 [xm ial insertions (Fig. IB). Longitudinal mus-
thick were stained with hematoxylin and cles strong, mesoectodermal; circular mus-
eosin (Humason 1979). Oocytes were mea- cles weak, en—dodermal (Fig. 3).
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sured following the method of Wedi Oral disc. Color in most individuals
Dunn (1983). red; in some orange or pink. Mesenterial
insertions clearly visible. Broad, tentacle-
Urticina mcpeaki, new species free region around mouth, usually white or
Figs. lA, B, 2-5 light olive green, gives way to distinctive
radial banding pattern, such that 12 thick
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Pedal disc. Circular, strongly adhesive. bands extend outward to spaces between
Color bright red; mesenterial insertions vis- first two cycles of tentacles (Fig. IB). Ac-
ible as darker red radiating lines. Well de- tinopharynx red, ribbed, with 2 red siphon-
veloped basilar muscles along each mes- oglyphs. Radial muscles strong, mesoecto-
entery. — dermal. —
Column. Bright red with many small, Mesenteries and internal anatomy.
white, adhesive verrucae. Verrucae usually Mesenteries arranged hexamerously in 4
heavily encrusted with debris (Fig. lA) and cycles. Fourth cycle usually incomplete;
arranged in longitudinal rows correspond- fourth cycle mesenteries added in exocoels
ing to endocoels and exocoels. No verrucae between first and third cycles first, then be-
on limbus. Well developed margin and tween second and third cycles. Typical ar-
fosse. Distinct round marginal structures; in rangement from half of an animal, directive
D43234143243414
life yellow, with dark-colored depression in to directive:
center (Figs. lA and 2A). Histology (Fig. 3 2 3 4 D. Number of mesentery pairs 29-
2B) and cnidae complement of marginal 44; one irregular individual with 52 pairs.
structures is not distinct from rest of col- Number of mesenteries same proximally
unm. When expanded, column generally and distally. Two pairs of directive mesen-
wider than tall. Maximum size of animals teries attached to siphonoglyphs. First and
^
654 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON
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VOLUME 112, NUMBER 4 655
Endodermal marginal sphincter muscle
circumscribed, large, strong; circular to
oval in shape (Fig. 3) and attached to col-
umn wall roughly halfway between fosse
and parapet. Laminae arranged pinnately
and of equal length on both sides of lamel-
la. —
Cnidom. Spirocysts, basitrichs, holo-
trichs, and microbasic p-mastigophores
(two types).
Distribution and size ofnematocysts and
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spirocysts. In the following table, n sig-
nifies the number of individual capsules
measured, N signifies the ratio of the num-
ber of specimens in which a type of cnida
was found to the number of specimens ex-
amined, and measurements in parentheses
indicate individual capsules that fell outside
the range.
Tentacles (tip and base of inner and out-
er):
Spirocysts (Fig. 5A) 12.5-39.9 X 1.4-
= N =
4.4 fjim; n 528, 15/15
Basitrichs (Fig. 5B) 6.5-32.3 X 1.1-
= N =
4.8 [xm; n 709, 15/15
Holotrichs (Fig. 5C) (found only in
tips, particularly of outer tentacles)
13.8-23.3 X 2.9-4.9 ixm; n = 111,
N =
11/15
Column, including margin:
Fig. 2. Urticina mcpeaki, new species. A, View of Basitrichs (Fig. 5B) 4.5-9.2 X 1.0-2.5
column showing marginal structures (slanted arrow)
and verrucae (horizontal arrow). Scale bar =1.5 cm. luim; n = 46,N = 10/11
B, Histological section showing marginal structure and Basitrichs (Fig. 5B) 13.4-23.1 (35.4)
sphincter (s). Scale bar = 0.2 mm. C, Histological sec- X 1.5-4.6 \xm; n = 152, N = 11/11
tion showing verrucae with modified glandular ecto-
Actinopharynx:
derm (arrow). Scale bar = 0.2 mm.
Basitrichs (Fig. 5D) 19.2-38.9 X 2.5-
6.0 ixm; n = 245, N = 14/14
second cycles perfect. First cycle sterile; all
Microbasic p-mastigophores type I
subsequent cycles may bear gametogenic
(Fig. 5E) 16.5-29.2 X 4.0-7.6 ^-m;
tissue. Sexes separate. Maximum diameter = N =
n 64, 8/14
of ripe oocytes in section approximately
450 |jim. Retractor muscles strong, diffuse Mesenterial filaments:
to restricted (Fig. 4). Parietobasilar muscles Basitrichs (Fig. 5B) 11.5-29.8 (34.4,
well developed and extending from half to 36.2) X 1.9-4.1 iJim; n = 207, N =
entire distance from column to retractor 11/11
muscle, terminating in free flap (Fig. 4). Microbasic p-mastigophores type I
Marginal stomata present; oral stomata not (Fig. 5E) 11.7-30.3 (33.1) X 3.5-
= N =
seen. 6.8 ^JLm; n 122, 11/11
656 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON
Fig. 3. Urticina mcpeaki, new species. Histological section showing sphincter muscle and cross section of
tentacle. Scale bar = 0.25 mm.
Microbasic p-mastigophores type II ifornia, south at least to Asuncion, Baja
(Fig. 5F) 19.8-42.9 X 3.6-8.6 |jLm; California, Mexico.
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= N =
n 113, 11/11 Habitat. Subtidal, in shallow debris-
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Distribution. From Santa Barbara, Cal- filled depressions of rocks.
Fig. 4. Urticina mcpeaki, new species. Histological section showing oocytes and three pairs of mesenteries
with retractor muscles and parietobasilar muscles. Scale bar = 1 mm.
VOLUME 112, NUMBER 4 657
KUNHM
specimens examined deposited at
001038, 001162 through 001168.
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Etymology. The specific epithet
mcpeaki honors Mr. Ron McPeak, who first
noticed this species in 1958 and suspected
it was a new species of Urticina. He pro-
vided many of the specimens examined.
Discussion and Differential Diagnosis
Urticina mcpeaki, new species, fits the
generic description of Tealia {= Urticina)
sensu Carlgren (1949). It is an actiniid with
a well-developed pedal disc, adhesive ver-
rucae on the column, and a well-developed
fosse. It has a strong, circumscribed, en-
dodermal sphincter, and the longitudinal
musculature of the tentacles and radial mus-
culature of the oral disc are mesoectoder-
mal. The basitrichs ofthe actinopharynx are
larger than those of the tentacles.
The major morphological difference be-
tween U. mcpeaki and other species in this
genus is that mesenteries and tentacles of
the first three cycles are always arranged
hexamerously. Mesenteries in the fourth cy-
cle are not added simultaneously, resulting
in a break of the hexamerous pattern. In
other species of Urticina, mesenteries and
tentacles are usually arranged decamerously
(Carlgren 1893, 1921, 1949; Hand 1955,
Fig. 5. Urticina mcpeaki, new species. Cnidae si| &
nature. See text for explanation. Scale bar = 5 (xm. Sebens Laakso 1977, Manuel 1981).
Hexametry in U. mcpeaki is unusual, but it
is not unique within Urticina. Several au-
—
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Type material and locality. Holotype thors (e.g., Carlgren 1902, 1949; Sebens
collected May 1997 from Point Loma, San Laakso 1977, Zamponi & Acuiia 1996) re-
Diego, California at 15 m; deposited at the fer to specimens of Urticina in which the
CASIZ 114595. Histological slides of spec- arrangement of either the mesenteries or the
imen also deposited. tentacles is not strictly decamerous, but
Paratypes from type locality CASIZ rather hexamerous.
114596 and 114597, Santa Barbara Muse- The new species can also be distin-
um of Natural History (SBMNH) 145138 guished from other species in this genus by
and 145139, University of Kansas Natural its geographic range. Urticina mcpeaki oc-
History Museum (KUNHM) 001041, Na- curs as far north as Santa Barbara, Califor-
tional Museum of Natural History (NMNH) nia (Jack Engle, Ron McPeak, pers.
99971 and 99972, and Royal British Co- comm.). The geographic ranges of all other
lumbia Museum (RBCM) 998-221-1. Par- species of Urticina on the west coast of
atype from the Coronados Islands also de- North America extend at least as far north
RBCM
posited at 998-222-1. Additional as Vancouver Island, British Columbia,
658 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON
Canada. Most species are found as far north are absent from the limbus. In U. lofotensis,
as Alaska (Gotshall 1994). The range of U. verrucae extend to the limbus where they
mcpeaki overlaps with the ranges of U. Co- are smaller and closer together than the ver-
lumbiana, U. coriacea, U. lofotensis, and rucae of the column.
U. piscivora (Ron McPeak, pers. comm.). Lastly, the two species differ in size. The
Of all species of Urticina on the North pedal disc diameter in the largest specimens
American Pacific coast, U. mcpeaki most of U. mcpeaki is 6 cm, while in U. lofoten-
closely resembles U. lofotensis externally. sis it can reach to 18 cm (Sebens & Laakso
Both species have a bright red column with 1977).
distinct white verrucae arranged in longi- This is the first detailed description ofthe
tudinal rows. However, U. mcpeaki can be two types of microbasic p-mastigophores
distinguished externally from U. lofotensis found in the mesenterial filaments. Micro-
by the color pattern ofthe tentacles and oral basic p-mastigophore type I (Fig. 5E) is
disc. Urticina mcpeaki has a distinct lon- more oval than type II (Fig. 5F) and has
gitudinal stripe on the otherwise uniformly pronounced serrations all along its robust
colored tentacles (Fig. lA). Urticina lofo- shaft. Cnidae of type II are usually larger
tensis does not have stripes on the tentacles than those of type I; however, there is some
and the color changes from yellow at the overlap in size within individuals. Type 11
base to red at the tip (Fig. ID). In U. are more slender than type I, in proportion
mcpeaki, the oral disc has a distinct radial to their lengths, and the serrations of the
banding pattern (Fig. IB), while the oral shaft are not as distinct. In a few individ-
disc of U. lofotensis lacks this pattern (Fig. uals, small numbers of microbasic p-mas-
ID). tigophores type I were also found in other
The structures at the margin of U. tissues (column, actinopharynx, and tenta-
mcpeaki differ from those of U. lofotensis. cle base). These capsules were considered
In U. mcpeaki they are yellow and have a contaminations of those tissues. Microbasic
dark-colored depression in the center (Figs. p-mastigophore type II were found only in
lA and 2A). The structures in U. lofotensis the mesenterial filaments. We have subse-
are white and do not differ in appearance quently found both types of microbasic p-
from the verrucae on the column (Fig. IC). mastigophores in U. columbiana, U. cori-
Histologically the marginal structures in acea, U. crassicomis, U. lofotensis, and U.
both species differ from verrucae. Verrucae, piscivora from the Northeast Pacific. In his
sensu Carlgren (1949), have modified ec- monograph on sea anemones of central Cal-
toderm (e.g.. Fig. 2C), which is lacking in ifornia, Hand (1955) included line drawings
the marginal structures. The distinct mar- of the two types of microbasic p-mastigo-
ginal structures of U. mcpeaki may be con- phores he found in the mesenterial fila-
fused externally with other marginal spe- ments of Tealia crassicomis (p. 74) and T.
cializations such as spherules or pseudo- lofotensis (p. 85) and the one type he found
spherules. However, they do not fit the in T. coriacea (p. 81). He did not describe
definition of marginal spherules or pseu- the differences between the two types. Our
dospherules, sensu Carlgren (1949), be- type I corresponds to Hand's line drawing
cause they have no distinctive histology labeled "g" for T. crassicomis and T. lo-
(Fig. 2B) or cnidae. fotensis, and "k" for T. coriacea. Our type
The verrucae of U. mcpeaki usually have II corresponds to Hand's line drawing la-
debris attached to them (Fig. lA). Although beled "h" for T. crassicomis and T. lofo-
the verrucae of U. lofotensis are capable of tensis.
attaching debris (pers. observation), speci- This is also the first description of a spe-
mens are usually found with no debris at- cies of Urticina that includes a size range
tached (Fig. IC). In U. mcpeaki, verrucae for tentacle holotrichs. In their report of
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VOLUME 112, NUMBER 4 659
several species of Urticina from British Co- Laboratory for helpful comments on the
lumbia, Zamponi & Acuna (1996) did not manuscript. Order of authorship was deter-
give sizes and probably identified the type mined by coin toss.
of cnidae we term holotrichs as atrichs.
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—
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1982) pointed out, atrichs and holotrichs
Bigger, C. H. 1976. The acrorhagial response in An-
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&
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—
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—
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Acknowledgments
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