Presence of Beania mirabilis Johnston in the Gulf of San Matías (Argentina), with a key to the Argentine species of Beania (Bryozoa, Cheilostomatida)

4 Pages·2001·0.19 MB·English

by  Gappa, Juan López

Reu. Mus.A rgentina Cienc. Nat., n.s.
3(1): 73-76, 2001
Buertus Area, ISSN 1514-5158
Presence of Beania mirabilis Johnston in the Gulf of San Matias
(hgentina),w ith a key to the Argentine species of Beania
I (Bryozoa, Cheilostomatida)
Juan LOPEZ GAPPA
Museohrgentino de Cicncias Naturales dernardino ltivadavia~>,AAv. ,G allardo 470, C1405DJR Buenoshires,
Argentina. E-mail: 1gappahail.rctina.ar
Abstracl: Beanirt mirabilis Johnston is recorded far the firstt ime inArgentina.I t was found on bivalve shells and
polychnete tubes in tbe intertidal and subtidal zones ofthe Gulf of Sanhlatias (40" 46'8, 64" 65'W,provinceo fRio
Ne~o,Argentina).'Chisre cord increases in more than 16" oflatitude its southern distribution lunit in the southwest
Atlantic Occan. An illustrated key for the identiiicalion of the eight species of Beania known for the Argentine
Sea is included.
Key words: Bryozoa, Cheilostomatida, Beaniii, key to species,A rgentina
The genus Beania Johnston, 1840, comprises species of this genus. It was originally described
more than 50 species distributed throughout the from matcrit~lc ollected by Charles Darwin in
world's oceans, including Antarctica. Reuniu is Patagonia and Cape Horn, although without
characterized by its reticulate or ramifiing giving precise localities within this region. B.
colonies, with zooids loosely attached to the australis was found again just once, off the state
substratum by rhizoids issuing from their basal of Szo Paulo, Brazil. This unlikely distribution
surfaces, and connected by tubular extensions. was confirmed, however, by the comparison of
Several species of Beania have been already the Brazilian material with the type specimens
recorded for the coast and the continental shelf of the species (Marcus, 1937).
of' Argentina (see Hastings, 1943; Amor & While processing intertidal and subtidal
Pallares, 1965; L6pez Gappa & Lichtschein, samples of benthic invertebrates from the Gulf
1990). The geographic distribution of H. costutu of San Maticis, several colonies of a species of
(Busk, 18761, B. fragilis (Ridley, 18811, B. Beania still unrecorded for Argentina were
znerrnis (Busk, 1852), B. magellanica (Busk, discovered. It was identified as Beania mirabzlis
18521,B.m axilla (Jullien, 1888) andB. unicornis Johnston, 1840, a widely distributed species,
(I-Iastings, 1943) between 35" and 56" S, and whose southern distribution limit known to date
between 50" W and the coast of Argentina has in the southwest Atlantic Ocean was Brazil. The
been summarized by L6pez Gappa (2000), and aim of this study is to document its presence in
maps showing known records of five species in coastal waters of Argentina. In addition, an
the Patagonian shelf have been published by illustrated key for the Argentine species of
L6pez Gappa & Lichtschein (1990). Beania is presented, in order to facilitate their
These species are usually found in cold- identification by other marine researchers not
temperate waters under the influence of the Familiar with the taxonomy of this group of
Malvinas Current. They have been recorded for benthic invertebrates.
the Maeellan Strait. Cane Horn. the Burdwood
Bank, &ound.the Malv;nas (Falkland) Islands,
Reania mirabilis Johnston, 1840
and along the coast and continental shelf off the
(Figs. 1, 2)
provinces of Tierra del Fuego, Santa Cruz and
Chubut' Only maxizla extends further north
Beanie rnirehilis Johnston, 1840:272,figs.1 ,2.
in Argentina, towards deeper shelf areas ,nirabilis: M ~1937:~ 60, ~~11fi,g~ . 29 ,
province of Buenos Aires (Roux et al., 1988). (Synonymy).
A little known species, B. australis Busk, BeaIaiaI nirabilis: Ryland & Flayward, 1977: 150,fig.
1852, can be added to the list of Argentine 73.
Revista del Museo Argentino de Ciencias Nata~ales,n . s. 3 ilj, 2001
S, 64" 63 W) Low intertidal and subtldal (0-5
m),VanVeen grab 26103199, collected by J 1,opez
Gappa MACK 34615 On Brachzdontes
rodr~guezls hells and polychaete tubes
Geographic Distribution
B. mirabilis is widely distributed in
temperate and tropical waters of the Atlantic,
Indian and Pacific Oceans, although its
geographic range seems to be based on more
than one species (see below). 111 the south
Atlantic, it has been previously recorded only
for Santa Helena Island (Marcus, 1938) and S&o
Panlo, Brazil (24" S) (Marcus, 1937). Its southern
distribution limit in this ocean is therefore ex-
tended in more than 1.6" of latitude. From the
intertidal zone up to B depth of 130 m (Marcus,
1937).
Obseruations
Figs. 1-2. Beania mirabilis ,Johnston, 1840. Pun- lnconspicuous colonies or this species were
ta Delgado, Gulf of San Matias, MACN 34615. found in the intertidal zone, on shells of the
Scale: 0.6 mzn. 1, Frontal view of zooid. 2, Late- mytilid Brachidontes rodriguezi densely
ral view of zooid. encrusted by spirorbid polychaehes. Less
frequent substrata were stones and the mussel
Mytilus edulis platensis. Other members of this
Diagnosis association were the rodophyte Polysiphonia sp.,
Colony uniserial, ramified. Zooids suberect, the bryozoan C~yptosulapallasiara~nad sponges.
0.55-0.60 mm long, spaced 1.1-1.7 zooid lengths In subtidal samples, B. mimbilis was found on
from each other, anchored to the substratum by B, rodriguezi shell fragments cemented to
rhizoids and connected by stolons. Three stolons polychaete tuhes, together with the bryozoan
per zooid, issuing latero- and mebio-proximally Celleporella hyalina.
from the base of the zooid. Two pairs of short In a recent study, Tilbrook el a?. (2001)
and erect spines around the operculum. Usually reported that several specimens apparently
6 (sometimes 7 or 8) pairs of sho1.t and delicate belonging to B. rnirabilis from Australia,
spines on each lateral margin, arched over the Vanuatu and the Mediterranean,might actually
frontal membrane. Avicularia and ovicells be regarded as iicw species, Differ,ences in zooid
absent. length and spacing, and number of marginal
spines between the I'atagonian material and
Material British specimens ofB. mirabilis are very slight,
Punta Delgado, Gulf of San Matias, province and do not seem to justify the introduction of a
of Rio Negro, Argentilia (approximately 40-46' new species.
KEY TO THE ARGENTINE SPECIES OF BEANIA 1
1. Usually onc or two avicularia per zooid, facing frontally
- Avicularia absent, or less frequent and pointing toward
2. Marginal spines arched over the frontal membrane. Usually one avicularia per zooid .......... 3
- Marginal spines absent. Two avicularia per zooid ...............................R.. magellanica (Fig. 3)
3. Three pairs of erect spines around the operculum. Operculum bearing one pair of irregularly
star-shaped processes B, maxilla (Fig. 4)
g one pair of horn-shaped
B costata (Fig. 5)
- Zooids erect or suberect
.
5. Marginal spines delicat , . .. . .. , .. . . . . .
I
Ldpez Gappa Presence of Beania mzrabzl~si n Argentzna
Figs. 3-10. Schematic view of zooids in the 8 species of Beania recorded for Argentina. 3, Beania
magellanica. 4, B. maxilla. 5, B, coslata. 6,B. inermis. 7, B. unicornis. 8, B. fragilis. 9, B. mirabilis.
10, B. australis. Figs. 3-7, frontal view, Figs. 8-10, lateral view. Not to scale. Modified from Ldpez
Gappa & Lichtschein (1990) (Figs. 3-5 and 8), Amor & Pallares (1965) (Fig. 61, Hastings (1943)
(Fig. 71, Ryland & Hayward (1977) (Fig. 9), and Marcus (1937) (Fig. 10).
76 Reuzsta rlel Museo Argentzno de Czenczas Nalurales, 12 s 3 (I), 2001
- Numerous and well developed marginal spines. Zooids well separated among each other ..............
................................ ...................................................................................... B. unicornis (Fig. 7)
6. Spines numerous, long, and conspicuous, located even at the dorsal surface of the zooid, pointing
. .
in all d~rections.. ..................... ... ...............................................................B. . fragilis (Fig. 8)
-
Spines only along the edge of the frontal membrane, or around the opercuium ..................... 7
7. Spines short and delicate, not covering the frontal membrane .................. B. mimbilis (Fig. 9)
- Two series of well developed spines covering the frontal membrane ....... B australis (Fig. 1.0)
ACKNOWLEDGEIVIENTS 1883). Zoo1 6 1-94 Cauthiei-Villdrs et Cie Paris
Lopez Gappa, J 2000 Species rlchnoss of mar.in*e-
1 am indebted to ~~~~~d~ ~ ~ and~ ~Bryo~koain tdhe con tinental shelf and slope off
Alejandro for their advice on the use of gentina (south-west Atlantic). Diurrsity and
Distributions, 6: 15-27.
soft~refo r the design and edition of digital
Lhi,ez Craplla, J. & ". Lichtschein. 1990. briozoos
images. The National Council for Scientific
,,~,,,i,,,~i~s pore ~ ~ / ~ ~ j ~ i , ~ h ~ i ~ ~ ~ ~ ~ l ~ ~ l ~ ~ ~ .
Research and Technology (CONICETI of Argen- lbrma continental nreentina. Scm. Hidraer. Na-
tina is gratefully acknowledged fir financial val, Buenos Aires, :i2 pp. v
support to the author during the course of this Marcus, E. 1937.B ryozo:iriosrniirinhos brasileiros. I.Bol.
study. Fat. Phil. Sei. Letr. Uniu. SrioPaulol, Zool. 1: 1-224.
- 1938. Papers from Dr. Th. Mortensen's I'acifie
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