TWO NEW HYDROMEDUSAE FROM THE CALIFORNIA COAST

TWO NEW HYDROMEDUSAE FROM T H E
CALIFORNIA COAST
2
LIBBIE H. HYMAN
Reprinted f ran TRANSACTIONS
OF THE AMERICAN MICROSCOPICAL
SOCIETY
Vol. LXVI, No. 3, J u l y , x
TWO NEW HYDROMEDUSAE FROM THE
CALIFORNIA COAST
LIBBIE H. HYMAN
American Museum of Natural History, New York City
These two medusae have attracted attention on the California coast as
forms in need of taxonomic treatment. Although they are not closely related, they are ecologically similar, being_ provided
with adhesive structures
_
for a semi-sedentary life in t
Suborder Anthomedusae
Family Cladonemidae
Cladonema californica, n, sp.
Material. Many well-preserved specimens sent by Dr. F. A. Pitelka, of
the University of California.
Bell and manubrium. The bell is of rounded form, widest above the
middle (Fig. l), a little shorter than wide. The larger specimens measure
2-3 mm across the widest part. No definite coloration was evident on the
preserved specimens. The wallof the bell is rather thin with no great amount
of jelly. There is a strong muscular velum of considerable width. The manubrium, dependent from the under side of the bell summit, can be extended
through the aperture of the velum to a considerable extent. The manubrium
consists of two regions, an upper and broader region with irregular contour,
and a lower region of firm, smooth appearance. The upper part, constituting
about three-fourths of the manubrium, is ridged and wrinkled; it increases
in diameter to the area bearing the gonads, then decreases again, with a
final abrupt decrease to the distal smooth region. The gonads form elongated, rounded protrusions around the manubrium, usually six, sometimes
seven in number. The smooth distal part of the manubrium bears six dark
longitudinal stripes, consisting of rounded pigment granules, and near the
end between these stripes are six very short oral tentacles, each terminating
in a nematocyst head (Fig. 2). The radial canals springing from the summit
of the manubrium are simple, straight canals that enter the ring canal.
Their number is the same as that of the tentacles, nine, rarely eleven. On
the bell margin there is an elongated eye-spot a t the junction of each radial
canal with the ring canal.
Tentacles. As already indicated there are nearly always nine tentacles
but one of the specimens has eleven. The tentacles have the structure
characteristic of the genus. There is a short basal stem in which the thickened epidermis forms a tentacular bulb (Fig. 3). This as in other hydromedusae (Hyman, 1940a) is packed with nematocysts, being in fact a depot
for the formation and distribution of nematocysts. Shortly distal to the
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NEW HYDROMEDUSAE FROM CALIFORNIA
263
tentacular bulb the tentacle forks into two or three branches (Fig. 3 ) . One
of these branches terminates in a sucker and may be called a sucker-branch
and the others, that may be termed stinging branches, are ordinary tentacles
armed with warts loaded with nematocysts. The smaller specimens have
one stinging branch, the larger two, and it appears that the second stinging
branch is an outgrowth of the first. The tentacles and their branches are
hollow with conspicuous canals continuous with the canal system of the
bell.
Nematocysts. The nematocysts of Cladonema rcdiatzcm were studied by
Weill (1936) who found two types, stenoteles and desmonemes. The same
two types exist in C. californica except that there are two sizes of stenoteles
(Fig. 4). The tentacular warts contain several stenoteles of both sizes and
many desmonemes. The nematocyst heads of the oral tentacles consist
chiefly of stenoteles.
Histology. One specimen, a female, was sectioned and found to be well
preserved for histological study. The structure of the bell conforms to that
of other hydromedusae. The cuboidal exumbrellar epidermis is devoid of
muscle bases and rests upon a relatively thin layer of mesogloea. The subumbrellar epidermis is taller and provided with strong and obvious muscle
fibers. In the radial canals, the gastrodermis is very thin on the outer side,
much thicker on the inner side where the free cell ends contain food remnants. Sections through the manubrium show a thick gastrodermis packed
with food bodies and a greatly thickened epidermis filled with clusters of
interstitial cells and ovocytes in various stages of development. The gonadal
protrusions have the same structure as the manubrial wall, being simply
outfoldings of the latter. The production of eggs is proceeding just as extensively in the whole of the proximal three-fourths of the manubrium as
in the gonadal protrusions and it is this process that causes the ridged, irregular contours G f this part of the manubrium. On the other hand the distal
fourth of the manubrium which has a reduced diameter and a firm, smooth
appearance lacks participation in sex cell production and is provided with a
very thin epidermis. It is evident that this medusa is strictly dioecious.
The main point of the histological examination was the structure of the
suckers. They are formed of a very thick epidermis consisting of tall,
slender cells without muscle bases (Fig. 5). Between these cells occur spaces
that generally appear empty but here and there are occupied by vague
granular material. No good evidence was found of the occurrence of any
gland cells in the sucker. In the interior of the sucker is a thick pad of
mesogloea separating its epidermis from the termination of the gastrodermal canal. The stalk of the sucker has the same structure as the stinging
branches.
The heavy load of food bodies in the free ends of the gastrodermal cells
everywhere indicates that intracellular digestion occurs throughout the
264
LIBBIE H. HYMAN
gastrovascular system but as in other hydromedusae (Hyman, 1940a) this
process is most intense in the gastrodermis of the manubrium and the basal
parts of the tentacular canals.
Habits. Occurs on mud flats covered with Ulva that are more or less
exposed a t very low tides; swims about in pools left by the tide and also
clings to the Ulva.
Locality. Found in a protected cove a t the upper end of Tomales Bay,
branch of Bodega Bay, Marin County, California; collected May 31, 1943.
Was not found in intensive studies o€ this area in May and June, 1941, nor
in June, 1945.
Differential diagnosis. C. californica difters from other species of the
genus in the morphology of the tentacles which branch into one suckerbranch and one or two stinging branches.
Type. One whole mount deposited in the American Museum of Natural
History, Cat. No. 3264,
Order Trachylina
Suborder Trachymedusae
Family Olindiidae
Vallentinia adherens, n. sp.
Material. Some ten years ago while a t Pacific Grove, California, making
studies of invertebrates for my book (Hyman, 1940b), I had a few specimens of this medusa, and made two drawings reproduced in this book (p.
458). I have been unable to obtain further material and hence the description is based on these figures, here reproduced,(Figs. 6 and 7). Ordinarily
one would not wish to make a taxonomic description without additional
~~
EXPLANATION OF FIGURES
FOR ALL FIGURES
1, manubrium; 2, oral tentacles; 3, eye-spot; 4,radial canal; 5, sucker-branch; 6 , stinging
branches; 7 , velum; 8, sucker-tentacles; 9, gonad; 10, statocysts; 11, tentacular bulb; 12,
stinging tentacles; 13, cirri; 14, ring canal; 15, nematocyst warts and ridges; 16, sucker; 17,
tentacular canals; 18, adhesive pads; 19, stenoteles; 20, desmoneme; 21, epidermal cells of
sucker; 22, mouth; 23, pigment stripe; 24, mesogloea1pad inside sucker.
PLATE I. Cladonema californica
FIG. 1. Cladonema californica; only five of the nine tentacles and radial canals are shown.
FIG. 2. Distal end of the manubrium of C. californica, showing oral tentacles and pigment
stripes.
FIG. 3. Tentacle of C. californica, enlarged, showing sucker-branch, two stinging branches,
and tentacular bulb filled with nematocysts.
FIG. 4. Nematocyst types of C. californica; desmoneme and two sizes of stenoteles.
FIG. 5. Section through the sucker of the sucker-branch, showing attenuated epidermal cells
of which it is composed.
26.5
N E W HYDROMEDUSAE FROM CALIFORNIA
PLATE I
e
266
I
LIBBIE H. HYMAN
material but the salient features of the medusa are evident in the drawings
and the animal is well-known a t Pacific Grove and consequently in need of
being given a name.
Description. I n general form and appearance this medusa closely resembles the familiar Gonionemus mwbachii and seems to be regarded locally
as a species of Gonionemus. The bell has the form of a shallow bowlwith the
short quadrangular manubrium dependent from the center of the under
surface of the summit. The four radial canals, equally spaced, proceed from
the summit of the manubrium to the ring canal in the bell margin. The
gonads in the form of a ruffled fold as in Gowionemus are borne on the under
surface of the radial canals. There is a well-developed muscular velum. The
bell margin bears numerous stinging tentacles, at least forty in number,
very similar to those of Gonionemus. They are hollow extensions provided
with circular ridges filled with nematocysts and a t least some of them bear
towards the distal end an adhesive pad devoid of nematocysts and employed
in clinging to objects. The bases of the tentacles pass through the jelly of
the bell margin (Fig. 7) and where they join the radial canal are provided
with a tentacular bulb composed of thick epidermis packed with nematocysts. I n place of four of the tentacles there are suckers on long stalks, distributed fairly evenly around the periphery but ..,--.-not perradial- in position.
These may be termed sucker-tentacles in contrast to the stinging tentacles.
They are hollow without nematocyst ridges but provided with tentacular
bulbs, and sucker-tentacles and stinging tentacles form one series of which
all the bases are imbedded in the jelly. I n addition to this series, there is a
series of small tentacles, called cirri by some authors, shown in Figure 7,
that do not have their bases imbedded in the jelly but spring directly from
the,margin. Th-ex-are provided with small tentacular bulbs a
with Gngs of nematocysts but lack adhesive dsIThey more or less alternate with the large tentacles. Thus V . adherem has two sets of tentacles as
in some other Olindiidae, showing different modes of attachment to the bell
margin. Along the bell margin between the bases of the large series are
conspicuous statocysts, o_n_ee-or
two between successive tentacle bases. They
appear to project freely to the--outer side of the bell margin. The nematocysts were not examined.
Habits. Found clinging to algae in shallow water near the shore.
Locality. Pacific Grove, California, near the Hopkins Marine Station.
Differential dicgnosis. V . adherens differs from the other known species
of the genus, V.falkZandica Browne 1902, in the following characters: flatter
bell, larger number of tentacles and statocysts, ruffle form of the gonads,
and non-perradial position of the sucker-tentacles.
Type. No type specimen is available. If a specimen can be obtained
later, it will be deposited in the American Museum of Natural History.
Remarks. I n 1902, Browne created the genus Vallentinia for a single
^
_
I
1
1
i
@
.
*-I
.
N E W HYDROMEDUSAE FROM CALIFORNIA
267
PLATE 11. Vallentinia adherens
FIG. 6. Vallentinia adherens, viewed from the subumbrellar side, showing the four sucker
tentacles among the numerous stinging tentacles,
FIG. 7. A small stretch of the bell margin of Vallsntinia adherens, showing tentacular bulbs,
cirri, statocysts, and mode of attachment of the two series of tentacles to the bell margin.
specimen collected in the Falkland Islands, probably found clinging to kelp.'
He defined the genus on the presence of the four sucker-tentacles replacing
four of the stinging tentacles. His description is fairly satisfactory but fails
to state if the stinging tentacles are provided with adhesive pads and if
cirri are present, and unfortunately no figures were given. This medusa has
not been taken again. The supposition of Mayer (1910, p. 352) that Val2entinio falklandica is probably an immature Qlindias i s difficult to under-
x
268
LIBBIE H. HYMAM
stand for in the first place Browne's medusa had gonads and in the sec
place one would have to assume a later transformation of the suckertentacles into stinging tentacles, something that appears quite impossible.
With the finding of another: species provided with sucker-tentacles, there
remains no doubt of the validity of the genus Vallentinia.
I n recent years, Kramp (1938, 1940) has maintained that the Olindiidae
should be removed from the Trachylina and together with the families
Moerisiidae and Williidae placed under the Eydroida in a separate suborder
Limnomedusae. I do not consider myself competent to judge the validity of
this change but it must be admitted that the Olhdiidae have strong resemblances to the Leptomedusae.
CITATIONS
'
Browne, E. T. 1902. A preliminary report on hydromedusae from the Falkland Islands. Ann.
Mag. Nat. Hist. 9, ser. 7 : 272-284.
Hyman, L. H. 1940a. Experiments and observations on the physiology of medusae. Biol. Bull.
99: 282-296.
1940b. The Invertebrates: Protozoa through Ctenophora. New York, McGraw-Hill Co.,
726 pp.
Kramp, P. L. 1938. Die Meduse von Ostroumanovia inkermanica (Pal.-Ostr.) und die syatematische Stellung der Olindiiden. 2001. Anz. 122: 103-108.
1940. Occasional notes on Coelenterata. 111.A. On the systematical position of the Williidae. Vidensk. Meddelel. Dansk Naturhist. Foren. 103: 503-510.
Mayer, A. G. 1910. Medusae of the world. Carnegie Inst. Washington, Publ. No. 109, vol. 11,
p. 352.
Weill, R. 1936. Le cnidome des cladonCmides Eleutheria dichotoina et Cladonema radiatum,
son cycle et son interpr6tation. C. R. Acad, Sci, Paris 203: 816-818.
.
.