A New Species Of Dorvilleidae (Annelida : Polychaeta) From A Cold Seep Site In The Northeast Pacific

7 Pages·2001·2.2 MB·English

by  B Hilbig

PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON
114(2):396-402. 200L
A new species of Dorvilleidae (Annelida: Polychaeta) from a cold
seep site in the northeast Pacific
Brigitte Hilbig and Dieter Fiege
(BH) Zoologisches Institut und Museum der Universitat Hamburg, Martin-Luther-King-Platz 3,
20146 Hamburg, Germany;
(DF) Forschungsinstitut Senckenberg, Senckenberganlage 25, 60325 Frankfurt/M., Germany
—
Abstract. Parougia oregonensis, a new species of the Dorvilleidae (An-
nelida: Polychaeta), is described from 5 specimens collected from a cold seep
m
site at 600-800 depth in the northeast Pacific at the Cascadia Margin off
Oregon. This new species differs from all other species of Parougia in the
degree of sclerotization of the mandibles, which are anteriorly smooth rather
than serrated, and in morphological details of the maxillae. Parougia orego-
nensis is the first member of the Dorvilleidae to be recorded from a cold seep
site.
During a joint German-Canadian-U.S. is reported from deep waters of the north-
project conducted in summer 1996 to study east Pacific, and P. wolfi was described
the cold seep sites along the Aleutian con- from hydrothermal vents of the Juan de
vergence zone, a few days were set apart Fuca Ridge, P. caeca from the Arctic and
initially to deploy the Canadian ROPOS P.fi^rcata from the Antarctic, while P. elia-
(Remotely Operated Platform for Ocean soni and P. nigridentata were described
Sciences) at the Cascadia convergent mar- from Norway and Skagerrak, respectively.
gin off Oregon. In this area, an abundant The new species is the first in this genus to
deep-sea benthic community, dominated by be recorded from cold seep environments.
the vestimentiferan tube worm, Lamellibra-
chia barhami Webb, 1969 and the clams, Material and Methods
Calyptogena sp. and Solemya sp. had been
m
observed before at a depth of ca. 2000 The material was collected during ajoint
(Suess et al. 1985). Investigations were per- German-Canadian-U.S cruise with R/V
formed at the Second Accretionary Ridge Sonne (SO 110 leg la, July 1996) to the
(=Hydrate Ridge) near ODP-site 892 where Second Accretionary Ridge =Hydrate
(
&
gas hydrates and active fluid venting had Ridge) off central Oregon (Suess Bohr-
been shown to occur near the summit of mann 1997). For collecting either a TV-
this ridge during ODP leg 146 and cruise grab (TV-G) or the ROPOS system was
109 of RA^ Sonne (Herzig et al. 1997). used. Drawings were made using a Leitz
Among the fauna collected were five spec- microscope and Wild dissection micro-
imens of a previously undescribed dorvil- scope. The pharynx was dissected and kept
leid polychaete belonging to the genus Par- in glycerin over night for better visibility of
ougia. To date, the genus is represented by thejaws. For scanning electron microscopic
only six species: P. caeca (Webster & Ben- (SEM) investigations, one specimen was
edict, 1884), P.furcata (Hartman, 1953), P. dehydrated via a graded ethanol series, crit-
batia (Jumars, 1974), P. eliasoni (Oug, ical point dried using COj, coated with Au-
1978), P. nigridentata (Oug, 1978), and P. Pd, and examined in a CamScan CS 24
wolfi Blake & Hilbig, 1990. Parougia batia SEM.
VOLUME 114, NUMBER 2 397
Fig. 1. Parougia oregonensis, new species. SEM micrographs of paratype (SMF A, anterior end.
anteroventral view; B, C, furcate chaetae; D, subacicular chaetae.
398 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON
mm
1
500|jm
Fig. 2. Parougia oregonensis, new species. A, entire animal, paratype (ZIM-P24243), dorsal view; B, para-
podium, middle segment, anterior view; C, furcate chaeta; D, E, subacicular, compound chaeta, shortest and
longestblades offascicle; F, smallcompoundchaetafromtipofinferiorsubacicularlobe. B-C,paratypeLACM-
AHF Poly 1969; D-F drawn to scale.
Material has been deposited in the col- Family Dorvilleidae Chamberlin, 1919
lections of the Zoologisches Institut und Genus Parougia Wolf, 1986
Museum, Hambu—rg, (ZIM), Los Angeles Parougia oregonensis, new species
County Museum Allan Hancock Founda- Figs. 1-3
tion, Los Angeles (LACM-AHF) and the —
Senckenberg Museum, Frankfurt (SMF). Material examined. NE Pacific, off
VOLUME 114, NUMBER 2 399
Oregon, Cascadia Margin, Second Accre- tional s-shaped ciliary bands running along
tionary Ridge (^Hydrate Ridge): SO 110/ anterior margin of palps and lateral margin
la, ROPOS 339, 10 Jul 1996, 44°40.2'N, of antennae. Peristomium biannular, ante-
125°6.5'E, 632 m, Pete Vent; holotype (SMF rior ring dorsolaterally split into 2 rings fus-
8897), 1 paratype (ZIM P-23243), 1 para- ing again ventrolaterally and produced ven-
type (LACM-AHF Poly 1969); SO 110/la, trally into crenulated lower lip; posterior
ROPOS 341 SS 1 (=suction sample 1), 12 ring simple, about as long as following
Jul 1996, 44°40.12'N, 125°05.80'E, 595 m, chaetigers.
northern summit of Hydrate Ridge; 1 para- Segments short and crowded throughout,
type + 1 posterior fragment (SEM stub 581, with highly arched dorsum and flat ven-
SMF 8898); SO 110/la, TV-G 18, 13 Jul trum; ciliary bands restricted to dorso- and
1996, 44°34,235'N, 125°08.891'W, 785 m, ventrolateral areas, continuing onto para-
southern summit of Hydrate Ridge; 1 para- podia and dorsal cirri. Parapodia very long
type (SMF 88—99). and slender, exceeding segmental width
Diagnosis. Generic definition accord- where best developed (Fig. 2A, B). Noto-
ing to Wolf (1986). Parapodia with supra- podia present from chaetiger 2, reduced to
chaetal, acicular, postchaetal, and inferior slender, tapered dorsal cirri supported by
chaetal lobes; dorsal cirri with long, tapered delicate acicula in cirrophore; cirrostyle
cirrophores, about as long as cirrostyles in short, pointed in anterior parapodia, in-
middle and posterior chaetigers; furcate creasing to about length of cirrophore
chaetae numerous, with long serrated sub- (when fully extended) in midbody and pos-
distal portion and smooth-tipped tines; su- terior parapodia; dorsal cirri subequal in
bacicular chaetae of 2 sizes, those in infe- length to neuropodia when relaxed; all
rior chaetal lobe much thinner than those of parapodial structures with varying propor-
acicular lobe. Mandibles smooth, delicate, tions due to muscle contraction during fix-
winglike; maxillae without inferior basal ation. Neuropodia with small digitiform su-
plates, with superiorbasal plate and heavily prachaetal lobe; short truncate acicular
sclerotized superior free denticles and del- lobe; triangular, somewhat longer postchae-
icate inferior denticles, distal ones with tal lobe; conical, often retracted inferior
whiplike termin—al tooth. chaetal lobe; and subterminal, digitiform
Description. Holotype: length about 17 ventral cirrus (Fig. 2B). Aciculae and bases
mm (coiled), width 1.0 mm, excluding of chaetae emerging from inferior chaetal
parapodia, for about 85 segments; paratypes lobe honey colored, other chaetae translu-
mm mm
5.5 to 12 long, 0.7 to 1.5 wide, cent.
about 47 to 80 segments. Color in alcohol Chaetae long and flowing, most numer-
uniformly pale. Prostomium broadly round- ous in anterior parapodia; supra-acicular
ed, wider than long, slightly widening to- chaetae of 2 types, serrated capillaries and
ward posterior margin, ventrally forming furcate chaetae with long, slender, unequal
large, medially incised upper lip (Figs. lA, tines and subdistal serration (Figs. IB, C,
2A). Antennae broken off on most speci- 2C); long tine about 2.0-2.5 times longer
mens, leaving deep, distinct scars; right an- than short tine, both with small hood-like
tenna on one specimen simple, tapering, structure on tip but not pubescent; subaci-
about 4 times as long as prostomial width cular chaetae compound with smooth
(Fig.lA). Palps about twice as long as pro- shafts, distally minutely serrated (visible
stomial width, evenly tapered, with short, only with SEM), and bidentate blades of
slightly clavate palpostyle, inserted lateral slightly varying length, tips appearing fine-
and slightly anterior to antennal scars; eyes ly serrated in SEM and equipped with
absent. Nuchal organs located at posterior sheath by light microscopy (Figs. ID, 2D,
prostomial margin behind antennae; addi- E). Small fascicle ofchaetae emerging from
400 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASfflNGTON
Fig. 3. Parougia oregonensis, new species, paratype LACM-AHF Poly 1969. A, maxillae, dorsal view, left
inferiordenticlerowomitted; B,C, superiorfreedenticle,dorsalandventralview;D,upperinferiorfreedenticle;
E, mandibles; A, E drawn to scale.
tip of inferior lobe distinctly thinner and trolateral anal cirri (all broken off, scarsdis-
shorter than remaining chaetae (Fig. 2F). tinct); anus slightly dorsal.
Pygidium ring-shaped, with long, conical Maxillae consisting of 2 rows of denti-
ventromedian style and apparently 2 ven- cles, superior row with basal plates (Fig.
'
VOLUME NUMBER
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402 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OFWASHINGTON
3A). Basal plates relatively short, about chaetae, and the maxillary denticles aredel-
one-fourth of total length of superior max- icate and few in number; P. caeca lacks
illary row, with toothed edge, about 16 ma- suprachaetal parapodial lobes and has a
jor teeth alternating with very small ones; strongly sclerotized mandible with serrated
superior free denticles 14 or 15 on a side, cutting edge. All other species ofthe genus
heavily sclerotized oval plates with large Parougia also differ from P. oregonensis in
main fang and row of alternating small and the heavily sclerotized, anteriorly serrated
large teeth along cutting edge and sclero- mandibles and in morphological details of
tized ribs across plate, some bearing addi- the maxillae. A synopsis of some important
tional tooth directed upward (Fig. 3B, C). morphological characters among species of
Inferior basal plates absent; free denticles Parougia is g—iven in Table 1.
17 or 18 on a side, all broadly rounded, Etymology. The species is named after
delicate plates with very finely serratedcut- its type locality—off Oregon.
ting edge, from D6 on additional long, Distribution. Known only from cold
m
whiplike marginal tooth (Fig. 3D). Mandi- seeps off Oregon, about 600-800 depth.
bles wing-shaped, with slightly divergent
sclerotized handles and smooth cutting Acknowledgments
edge; wing-like anterior part of mandible We thank Heiko Sahling (GEOMAR,
with sclerotized rib between tip of handle Kiel) for making the material available to
and anterior—margin (Fig. 3E). us and for information on the collecting
Remarks. Most dorvilleids described site. Jim Blake and an anonymous reviewer
from deep water in general, and geologi- are thanked for their helpful comments.
cally active sites in particular, belong to ei-
ther Ophryotrocha or Exallopus (for ex- Literature Cited
& &
ample, Blake Hilbig 1990, Hilbig
Blake 1991). Species of Parougia reported Blake, J. A., & B. Hilbig. 1990. Polychaeta from the
vicinity of deep-sea hydrothermal vents in the
from deep waters of the northeast Pacific Eastern Pacific II. New species and records
are P. batia (Jumars, 1974), P. caeca (Web- from—the Juan de Fuca and ExplorerRidge sys-
ster & Benedict, 1884) and P. wolfi Blake tems. Pacific Science 44:219-253.
& Hilbig, 1990, the latter being the only Herzig, P, E. Suess, & R Linke (eds.). 1997. RV Son-
ne. Cruise report SO109. Geomar Report 58.
dorvilleid from the Dorvillea-Ougia-Par-
250 pp. Geomar, Kiel.
ougia group so far described from geolog- Hilbig, B., & J. A. Blake. 1991. Dorvilleidae (Annel-
ically active environments, i.e., hydrother- ida: Polychaeta) from the U.S. Atlantic slope
mal vent systems. Parougia oregonensis, and rise. Description oftwo new generaand 14
new species, differs from P. wolfi most ob- new spec—ies, with a generic revision ofOphry-
otrocha. Zoologica Scripta 20:147-183.
viously in the presence oflong-tinedfurcate Suess, E., & G. Bohrmann (eds.). 1997. RV Sonne.
chaetae and distally entire rather than bi- Cruise report SOI10. Geomar Report 59. 181
dentate capillaries. Furthermore, P. orego- pp. Geomar, Kiel.
nensis has mandibles with a smooth rather , B. Carson, S. D. Ritger, J. C. Moore, M. L.
Jones, L. D. Kulm, & G. R. Cochrane. 1985.
than serrated cutting edge, and there are
large differences in the shape and degree of BsiuobldougcitciaolnczoomnmeunoiftfieOsregatont.h—e Bsuitlelsetailnonogf tthhee
sclerotization ofthe free denticles. This dif- Biological Society ofWashington 6:475-484.
ference can be easily seen by examining the Wolf, P. 1986. Three new species ofDorvilleidae(An-
maxillae in situ through a middorsal inci- nelida: Polychaeta) from Puerto Rico and Flor-
sion of the anterior thorax without further ida and a new genus fordorvi—lleids from Scan-
dinavia and North America. Proceedings of
dissection. Parougia batia is much smaller the Biological Society of Washington 99:627-
than P. oregonensis and has no furcate 638.