Studies on western Atlantic Octocorallia (Coelenterata: Anthozoa). Part 3: The genus Narella Gray, 1870

32 Pages·2003·19.5 MB·

by  Stephen D Cairns

PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON
116(3):617-648. 2003.
Studies on western Atlantic Octocorallia (Coelenterata: Anthozoa).
Part 3: The genus Narella Gray, 1870
Stephen D. Cairns and Frederick M. Bayer
Department of Systematic Biology (Invertebrate Zoology), National Museum of Natural History,
Smithsonian Institution, P.O. Box 37012, Washington, D.C. 20013-7012, U.S.A.,
e-mail: [email protected]
—
Abstract. The seven species of Narella known from the North Atlantic are
SEM
described and illustrated, often with the aid of stereo photomicrographs
in order to show the shape and relationships of the body wall sclerites. Two
species are described as new: A^. alvinae and A^. spectabilis, the former the
deepest known representative of this genus. Two keys, tabular and dichoto-
mous, are provided for the seven species. The types of all but one of the species
were examined; only photographs of the syntype were studied ofA^. bellissima.
New material is reported for all but one species, based primarily on collections
housed at the USNM and MCZ.
Like many primnoid genera, species of Iselin, Pillsbury, Gerda) and later deposited
the genus Narella have very conspicuous to the USNM. Other specimens were ob-
MCZ ROM
polyps composed of a discrete number of tained from the {Atlantis) and
large sclerites (scales), which are often del- {Alvin).
icately sculptured and arranged in a definite Designation of polyp scales follows the
pattern and number. In most species there terminology employed by Versluys (1906)
are only 16-18 sclerites in each polyp (ex- as amplified by Bayer et al. (1983). Syn-
clusive of tentacular sclerites), which are al- onymies for all species are purported to be
ways arranged in pairs. Even the eight oper- complete. The SEM photomicrographs
cular scales are paired across the sagittal were taken by the authors on a variety of
SEM
axis. Species of Narella live exclusively in microscopes both at the University of
deep water (146-3419 m) and are found Miami and the Smithsonian. Unprefaced
worldwide, including off Antarctica. One of SEM stub numbers pertain to the series of
the Atlantic species, N. alvinae, is the deep- Bayer, those prefaced with a C, to the series
est known for this genus and the second of Cairns.
deepest collected primnoid. Twenty-seven T—he following abbreviati—ons are used:
species of Narella are known: seven occur- Alb USFWS Albatross; Atl Atlantis and
BL—
ring in the Atlantic, 14 from the western RA^ Atlantis II U.S. Coast Survey
—
BM
Pacific, three from the Hawaiian Islands, Steamer Blake; British Museum (now
one from the southwest Indian Ocean, one The Natural History Museum, London);
— —
from the Galapagos, and one from off Ant- CI RTV Colombus Iselin; G RA^ Gerda;
—
arctica. H:W height to maximum width of an
—
opercular scale; JS Johnson-Smithsonian
—
Material and Methods Deep Sea Expedition;—JSL-II RA^ John-
son Sea-Link II; MCZ Museum of Com-
Most of the new specimens reported in parative Zoology, Harvard, Cambridge;
—
MOM
the paper were collected by vessels oper- Museum Oceanographique, Mona-
O—
ated by the University of Miami {Columbus co; M/V, R/V Oregon; P—R/V Pills-
618 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON
—
ROM
bury\ Royal Ontario Museum, On- pair meeting at the adaxial (lower) side of
SEM—
tario; SB—M/\, R/V Silver Bay; the polyp to form a complete ring, the other
Scanning Electron Microscope stub num- not. However, as some of the specimens in-
—
USNM
ber; United States National vestigated for the present account have
Museum (now the National Museum of some polyps with "closed" basal scales and
Natural History, Washington, D.C.). others with "open" basals, even on a single
branch, it appears that this character is not
Subclass Octocorallia reliable even at the specific level. It has
Order Alcyonacea therefore been omitted as a basis for clas-
Suborder Calcaxonia sification.
Family Primnoidae Gray, 1858 One of the most diagnostic features at the
Genus Narella Gray, 1870 species level among the Atlantic Narella,
and perhaps among all the species of this
Narella Gray, 1870:49 [type-species: Prim-
& genus, is the shape and sculpture of the
noa regularis Duchassaing Michelotti,
body wall sclerites, especially the basal
1860, by monotypy].
& sclerites, each species having a unique ar-
Stachyodes Wright Studer in Studer,
chitecture (shape) and surface texture
1887:49 [no species originally included;
(crests and/or granulation). But, this feature
type-species: Stachyodes regularis
& is difficult to determine, often requiring
Wright Studer, 1889 (not Duchassaing
SEM
& or various staining techniques to see.
Michelotti, 1860), —Stachyodes stu-
Thus, the dichotomous key, designed for
deri Versluys, 1906, by subsequent mon-
& ease of use, does not emphasize that char-
otypy (Wright Studer, 1889:54)].
& acter, rather the grosser characters such as
Calypterinus Wright Studer in Studer,
the branched or unbranched nature of the
1887:49 [no species originally included;
colony. Unfortunately, branching character-
type-species: Calypterinus allmani
& istics can be misleading, in that long
Wright Studer, 1889, by subsequent
& branches of a branched colony are often
monotypy (Wright Studer, 1889:53)].
collected separated from the main colony,
—
Diagnosis. Colonies of moderate size falsely suggesting that such a detached
(up to about 50 cm), dichotomously branch is an unbranched colony. Thus, we
branched in one plane or unbranched; pol- recommend favoring the tabular key (Table
yps facing downward in whorls or pairs, 1) for identification purposes, which gives
rarely isolated; 3 or 4 pairs of large abaxial a suite of characters for every species, in-
body scales, adaxial scales reduced to 1 cluding aspects of the basal sclerite archi-
well-developed buccal in each row, some- tecture and texture.
times with 1 or 2 more below it; operculum The four pairs of opercular sclerites of
consisting of 8 generally triangular scales all species of Narella appear to follow a
each with a more or less distinct longitu- similar pattern of size and shape. Sclerites
dinal keel on inner surface and correspond- of the adaxial pair are always the smallest
ing trough on outer; tentacles usually with in height and width (usually at least twice
numerous flat rodlets; coenenchymal scler- as tall as the basal width, shaped like an
ites as scales, generally elongated, some- isosceles triangle) and are symmetrical in
times with raised external crests; axis heavi- shape. The scales of the inner- and outer-
ly calcified, longitudinally grooved, with a lateral pairs are progressively taller and
discoidal basal holdfast attached to solid wider and asymmetrical, the adaxial side of
objects. each scale produced as a "shoulder" that
—
Remarks. Versluys (1906) divided the overlaps the edge of the scale to its adaxial
species of Narella (as Stachyodes) into two side. The abaxial operculars are invariably
groups, one with the sclerites of the basal the largest of the operculars, both in height
VOLUME 116, NUMBER 3 619
and width, the widest part occurring at 5'. Whorls of polyps more distantly spaced,
about mid-height (often resembling the 7-9 in 3 cm of axial length; usually 3
playing card spade) and are symmetrical, (2-4) polyps per whorl; outer surface of
having projecting shoulders on both edges. large body scales smooth except for
more or less conspicuous radial wrin-
The triangular shape of the operculars in-
kles N. pauciflora Deichmann, 1936
variably changes in the ad- to abaxial di-
6. Colonies sparingly branched dichoto-
rection, such that the ratio of height to max-
mously in one plan; polyps in whorls of
imum width decreases, essentially changing 3-5, with 5-7 whorls in 3 cm of axial
form isosceles to almost equilateral trian- length; body scales without longitudinal
gular. This ratio of height to maximum crests N. laxa Deichmann, 1936
width is often species specific and thus the 6'. Colonies apparently unbranched; polyps
term H:W is introduced herein to define this in whorls of 4, with 8 whorls in 3 cm
shape for the opercular scales. of axial length; body scales with longi-
tudinal crests TV. spectabilis, n. sp.
Key to the Seven Atlantic Species
of Narella Narella bellissima (Kiikenthal, 1915)
Figs. lA, 2A-C, 3A-D, 14
1. Polyps with 3 pairs of large body scales
2 Not Primnoa trilepis Pourtales, 1868:130.
—
1'. Polyps with 4 pairs of large body scales Stachyodes trilepis. Studer, 1901:41-42,
6
pi. 5, pi. 11,—figs. 3, 6, 7.
2. Colonies unbranched
Stachyodes sp. Versluys, 1906:123-124.
A^. versluysi (Hickson, 1909)
Stachyodes bellissima Kiikenthal, 1915:
2' Colonies branched, sometimes sparingly
.
154; 1919:457; 1924:310.
so 3 —
3. Colonies dichotomous branched in a Stachyodes regularis. Kiikenthal, 1919:
lyriform pattern; opercular scales cov- 466-467 (specimen from St. Vincent at
ered in abaxial view 88 fms, BL-232).
—
N. bellissima (Kiikenthal, 1915) Stachyodes Allmani. Thomson, 1927:29.
—
3'. Colonies dichotomous branched, but not Narella regularis. Deichmann, 1936:169,
—
in a lyriform pattern; opercular scales pi. 26, fig. 3. Tixier-Durivault &
visible 4 d'Hondt, 1974:1412.—Grasshoff, 1982a:
4. Distal margin of upper (i.e., "abaxial") 738, map 3; 1982b:947, figs. 15-17.
part of basal scales projecting conspic- — &
Narella bellissima. Grasshoff Zibrow-
uously as a pair of broad, flat, truncated
or rounded lobes standing approximate- ius, 1983: in part, 122-123, pi. 4, figs.
ly normal to axis; lateral part of basal 17-18 (not page 120, pi. 2, f—ig. 8).—Car-
&
scales abruptly meeting upper ("abaxi- pine Grasshoff, 1985:33. Grasshoff,
al") part at about 90°, ridged; sparingly 1986:26-27.
branched N. alvinae, n. sp. —
4'. Distal margin of basal scales projecting Material examined. Mona Passage:
only as a pair of short, rounded lobes, 18°12'N, 67°42'W, 515 m, 0-2644, 5 Oct
oriented downward to axis; lateral part 1959, 3 colonies almost complete save for
of basal scales meeting as smooth holdfast, USNM 52776 {SEM 378, 1734,
curve, not a 90° angle and not ridged; unnumbered stub made in 1971, CI031).
regularly and profusely branched 5
Off St. Vincent: 13°20'N, 61°02.5'W,
5. Whorls of polyps closely placed, 10-12
576-823 m, P-881, 6 Jul 1969, one small
in 3 cm of axial length; 5 or more pol-
colony almost complete but lacking hold-
yps per whorl; outer surface of large
body scales rough, closely covered by fast, USNM 52777 {SEM 380, 1723).
small, sharp granules A^. regularis West of Puerto Rico: 18°03'45"N,
(Duchassaing & Michelotti, 1860) 67°48'10"W, 439-549 m, JS-43, 11 Feb
1
^ \
620 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON
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622 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON
Fig. 1. A, Narella bellissima, 0-2644, USNM 52776, colony in two pieces, XO.33; B, N. regularis, Alb-
USNM USNM
2752, 49385, colony, X0.50; C, N. spectabilis, holotype, 57578, X0.67; D, N. pauciflora, ho-
MCZ USNM
lotype, 4809, X0.80; E, N. laxa, holotype in two pieces, 11853, X0.55; F, N. versluysi, C/-140,
USNM
57570, X0.55.
,
VOLUME NUMBER
116, 3 623
1933, 3 dichotomous branches, the tallest lyriform colony shape. The largest speci-
15.5 cm, USNM 54281 (SEM 412). men examined ((9-2644) has a main stem 2
West of Puerto Rico: 18°17'05"N, cm in height and 5 mm in axial diameter, a
67°24'45"W, 512-622 m, JS-47, 13 Feb total colony height of 43 cm, and approxi-
1933, one nearly complete small colony mately 14 branches that originate from each
with part of calcareous holdfast, and 6 de- of the subsidiary branches. The branches
tached branches, USNM 57444 {SEM 1726) originating from the two subsidiary branch-
Bahamas, off Egg Island, Eleuthera: es are up to 28 cm in length, most of which
25°30.85'N, 76°55.10'W, 790 m, JSL-II- bifurcate only once, some of which bifur-
813, 12 Apr 1984, branches cut from a cate twice, and several of which are un-
large colony, USNM 1004869 (SEM 1727). branched. The axis is strongly calcified,
Bahamas, off Chub Cay, Berry Islands: fairly stiff, and golden-yellow in color; it
25°23.40'N, 77°55.25'W, 792 m, JSL-II- bears fine longitudinal grooves. Polyps are
815, 13 Apr 1984, branches cut from a arranged in whorls of 3-8 (average 5), the
large colony, USNM 1004866 (SEM 1709, lower number characteristic of whorls at the
1711). ends of branches, the higher number found
Straits of Florida between Delray Beach, on larger-diameter basal branches. Whorls
Florida, and Grand Bahama Island: and polyps are so closely spaced that the
26°24'N, 79°36'W, 738 m, CI-140, 28 Sep branch coenenchyme cannot be seen, 10-
1973, one branch 14 cm tall, USNM 57568 13 whorls occurring in 3 cm branch length,
(SEM 1733). the tips of the opercular scales almost
Off Northwestern Spain, Bay of Biscay: touching the basal scales of the adjacent
44°irN, 8°40'W, 450-500 m, Thalassa proximal polyp and the sides of each polyps
USNM
V807, 28 Oct 1968, 2 branches, touching their adjacent polyp in the same
94560 and 94561 (SEM 894, 1712-1716) whorl. As is characteristic for the genus, the
(reported by Grasshoff, 1982b). polyps point downward; the length of a pol-
MCZ
Lesser Antilles: BL-232, 4807, sev- yp, as measured parallel to the axis from
eral colony and branch fragments now sep- basal scale to the tip of the operculars, is
arated into 8 lots, alcohol and dry, previ- 2.0-2.2 mm.
ously reported as A^. regularis by Deich- Each polyp is protected by three pairs of
mann (1936). large abaxial body scales and a pair of small
MCZ
Lesser Antilles: BL-233, 4808, sev- adaxial buccal scales. The pair of basal
eral branches now separated into two lots, scales are quite prominent, standing perpen-
mm
alcohol, previously reported as A^. regularis dicular to the axis up to 1.8 in height,
by Deichmann (1936). the upper half of each of these scales pro-
Photog—raphs of syntypes (MOM). jecting above the medial scales as a tall,
Types. Four syntypes are deposited at broad, rounded lobe. The sides of these bas-
MOM,
the one in alcohol and three dry al scales curve around the base of the polyp
&
(Carpine Grasshoff 1985), cataloged as and meet on the adaxial side in a ring struc-
12 0011. Type Locality: Hirondelle station ture, but do not fuse. At the point of cur-
105: 38°23'45"N, 30°5r30"W (off Azores), vature from the abaxial to lateral edges,
927 m. there is usually a low longitudinal ridge on
—
Description. Colonies have a short, the lower half of the sclerite. The pair of
stout main stem, which bifurcates into 2 medials are much smaller sclerites (0.7-0.8
mm
subsidiary branches, the angle between in length), roughly square, and slightly
these two branches being 100°—110°, each creased transversely, resulting in a slight
of which give rise to a series of regularly distal flare; they do not meet on the adaxial
spaced (every 12-15 mm) branches on their side. The pair of abaxial buccals are quite
mm mm
facing sides, altogether forming a uniplanar, large (up to 1 .3 in length and 0.90
624 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON
USNM
Fig. 2. Narella bellissima: A, B, JS-47, 51AAA, a complete polyp whorl and lateral view of a polyp;
C, JSL-II 815, USNM 1004866, adaxial view. Stereo views. All scale bars are 0.5 mm.
VOLUME NUMBER
116; 3 625
in width), and, although they do not meet dinal groove exteriorly and a more promi-
on the adaxial side, form a protective cone nent keel on their inner surfaces in the ad-
enveloping the distal polyp and opercular to abaxial gradient. At first glance, in situ,
scales, such that only the tips of the oper- it would appear that the operculars are flat
cular scales can be seen from side or ab- with a medial ridge, but when disarticulat-
axial view. The distal edges of these buc- ed, it can be seen that these sclerites are
cals are quite thin and delicate, appearing deeply longitudinally grooved with a keel
translucent for the distal 0.1 mm because of on lower face. When closed, the opercular
a lack of tubercles on their inner surface of scales form a tight, somewhat overlapping
this region. The three pairs of large abaxial crown around the polyp, which is also pro-
scales overlap each other slightly on the tected by the abaxial buccals, all of which
sagittal line and are covered by very small are directed toward the branch axis. The
granules arranged in lines that radiate from tentacles contain small (80 \xm length),
a central point on each scale about V3 the granulated, slightly curved spindles. The
distance up from its base; however, the coenenchymal scales are elongate and irreg-
granulation is so fine that these scales ap- ular in shape, arranged in one layer, up to
A mm
pear smooth. pair of quadrate-shaped ad- 1.2 in length, and usually longitudinal-
axial buccal scales also occurs just beneath ly ridged. The inner surfaces of all sclerites
the adaxial operculars, these scales measur- are tuberculate, except for the distal edges
mm
ing about 0.3 in greater width. Their of the body wall scales. The tubercles are
inner surface is tuberculate, the outer gran- roughly 10 |jim in diameter and spiny, the
ular, and their distal edges finely serrate, the individual spines being about 1 ixm in di-
serrations being 2—6 fxm in width. Rarely, ameter. —
one can observe in some specimens 10-12 Comparisons. Narella bellissima is the
pairs of vestigial adaxial scales that are el- only Atlantic species in the genus to have
mm
liptical in shape and only about 0.1 in dichotomous branching that results in a lyr-
greater diameter. iform colony. Based on Table 1, it is most
The adaxial operculars are elongate-tri- similar to A^. alvinae, both species having
mm
angular and symmetrical, up to 0.7 in prominent lobate basal scales, but A^. bellis-
mm
height and 0.31 in basal width (H:W sima differs in having smaller polyps and
= 2.1-2.9). They are longitudinally con- consequently more whorls per cm, less
cave, sometimes bearing a short medial prominent ridging on the body wall scales,
ridge within this concavity, and also bear- proportionately longer buccal scales and
ing a prominent medial keel on the distal smaller operculars resulting in the opercu-
half of its under surface. The inner- and lars being almost completely hidden from
outer-lateral and abaxial opercular scales view, and occurs at a shallower depth.
—
are only slightly taller and wider (up to 0.75 Distribution. Eastern Atlantic: Bay of
mm tall and 0.47 mm wide: H:W about Biscay off France and NW Spain (Grass-
1.3-16) and asymmetrical, such that there hoff 1982b, 1986); off Portugal (Grasshoff
is a slight shoulder on the adaxial side, 1986); Azores (Studer 1901, Tixier-Duri-
making the interior keel appear off-center. vault & d'Hondt 1974); Madeira (Thomson
The abaxial operculars are only slightly 1927, Grasshoff 1982a); Canary Islands
taller but much wider than the laterals, (Grasshoff & Zibrowius 1983); Cape Verde
mm
sometimes wider than tall (e.g., 0.78 Islands (Grasshoff 1986); ?Dakar (Grass-
tall and 0.80 mm wide: H:W = 0.81-1.0) hoff & Zibrowius 1983); 225-1968 m.
and symmetrical, bearing shoulders on each Western Atlantic: Lesser Antilles and Ba-
side at mid height, making the longitudinal hamas (Fig. 14); 161-792 m.
—
interior keel centrally placed. The opercular Remarks. Studer (1901) was the first to
scales have a progressively deeper longitu- describe and beautifully illustrate a speci-
626 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON
Fig. 3. A-D, Narella bellissima (A, B, D, (9-2644, USNM 52776; C, P-881, USNM 52777): A. underside
of abaxial, outer-lateral, inner-lateral, and adaxial opercular scales; B, three coenenchymal scales; C, a tentacular
scale; D, an adaxial buccal scale. E-H, Narella regularis from Alb-2752, USNM 49385: E, underside ofabaxial,
outer-lateral, inner-lateral, and adaxial opercular scales; F, three coenenchymal scales; G, two tentacular scales;
H, an adaxial buccal scale. Scale bars: A, B, E, F = 0.5 mm; C, G = 0.05 mm; D, H = 0.25 mm.