Redescription Of Helmetophorus rankini Hartman, 1978 (Polychaeta, Helmetophoridae) And Its Transfer To The Flabelligeridae

4 Pages·1991·1.9 MB·English

by  C J Glasby

PROC. BIOL. SOC. WASH.
104(4), 1991, pp. 684-687
REDESCRIPTION OF HELMETOPHORUSRANKINI
HARTMAN,
1978
(POLYCHAETA: HELMETOPHORIDAE) AND ITS
TRANSFER TO THE FLABELLIGERIDAE
Christopher J. Glasby and Kristian Fauchald
Abstract.—ThQ only representative ofthe Helmetophoridae, Helmetophorus
rankini Hartman, 1978, is redescribed and transferred to the Flabelligeridae.
The species shares in common with the Flabelligeridae a papillated body sur-
face,abuccalregionwithbranchiaeandgroovedpalpsthatiscovered(partially)
by a cephalic hood, weakly developed parapodia, and cross-barred capillaries.
The Helmetophoridae is currently rep- partiallycoveredbycephalichood.Oraltube
resentedbya single species, Helmetophorus non-retractile, cylindrical and muscular.
rankini Hartman, 1978, collected from the Branchiae, 5 pairs, of 2 types: 3 pairs cla-
Weddell Sea, Antarcticain 3111 m. The spe- vate-cirriform, arising from reduced bran-
cieshasnotbeenrecordedsincetheoriginal chial membrane; 2 pairs foliaceous, arising
description. During a recent study ofphy- posteroventrally to branchial membrane.
logenetic relationships of nereidoid poly- First parapodia lacking neuropodia (and
chaetes by CJG, it was found that Helme- neurosetae), subsequent ones with both
tophoridae was assigned to the order neuropodia and notopodia. All setae cross-
Phyllodocida: superfamily Nereidoidea by barred capillaries. Anterior setae directed
George & Hartmann-Schroder (1985:23). forward, but not prolonged and cage-form-
The classification of the Helmetophoridae ing.
was influenced by Hartman's (1978) opin- Remarks.—The most remarkable feature
ion that H. rankini resembled the Hesio- of this genus is the prominent oral tube,
nidaeinhavingthefirstthreesegmentswith which appears not to be retractable. Other
tentacular cirri, a muscular eversible pro- flabelligerids having an oral tube include
boscis, and biramous parapodia. We have Buskiella Mcintosh, 1885; Therochaeta
examinedthetype specimens of//, rankini, Chamberlin, 1919; and Therochaetella
plus an additional specimen from near the Hartman, 1967. Helmetophorus differs in
typelocality,andfindthatthisspeciesshould lacking a true cephalic cage, and in having
be transferred to the order Flabelligerida: an extremely reduced branchial membrane
family Flabelligeridae. withfewbranchialfilaments. Thegenusalso
shows some resemblance to Diplocirrus
Haase, 1915, in having branchial filaments
Order Flabelligerida
oftwotypes;however,Diplocirrushas4pairs
Family Flabelligeridae
ofbranchiae (Fauchald 1977:116). The ge-
Saint-Joseph, 1894
neric groupings within the Flabelligeridae
Genus Helmetophorus \i3.rXn\2in, 1978
are poorly understood (Chamberlin 1919:
Type species. —Helmetophorus rankini 397, Fauchald 1972:213), and it is not pos-
Hartman, 1978 by monotypy. sible to further evaluate the relationship of
Diagnosis.—¥\3)oQ\\\gQV\ds with buccal Helmetophorus within the family at this
apparatus (prostomium and peristomium) time.
VOLUME NUMBER
104, 4 685
Helmetophorus rankini Hartman from dorsal crest in branchial membrane;
Fig. la-d B3 arising posterior to B2 from branchial
membrane between ventral loop and mid-
HelmetophorusrankiniHartman, 1978:145, dorsalregion; B4arisinglaterallyjustbelow
fig. lla-f.
ventral loop of branchial membrane; and
Material examined.—YioloXypQ: USNM B5 arisingjustdorsolaterally to B4 (Fig. la,
46748, Antarctic Ocean, Weddell Sea, b).
USCGC
73°28.4'S, 30°26.9'W, Glacier Cr. Parapodia low, first pair with notopodia
2, Sta. 22, 3111 m, coll. J. S. Rankin, 13 only, remaining pairs with both noto- and
Mar 1969. Paratypes: 4 (USNM 46749), neuropodia;anteriorparapodiadirectedan-
collectiondetailsasforholotype. Non-type: terolaterally (Fig. la), posterior parapodia
1 (USNM 97424), Antarctic Ocean, Wed- directed posterolaterally. Notopodia and
dellSea, 73°52'S, 31°18'W, USCGC Glacier neuropodia with small retractile conical
Cr. 2, Sta. 21, 2288 m, coll. J. S. Rankin, lobes and small bundles of setae; distance
13 Mar 1969, det. K. Fauchald. between noto- and neuropodia similar
Description.—\lo\oXypQ complete with 22 throughout (Fig. Ic, d). True aciculae ab-
mm mm
setigers, 6.5 long, 0.8 wide maxi- sent, although 6 or so fine, short internal
mally; left 4th parapodium removed, not spinespresentventraltoneurosetae(Fig. Ic,
3rdasindicatedbyHartman(1978:fig. 11d); d).
moderately-well preserved, many setae All setae cross-barred capillaries, poste-
damaged. rioronesappearingtohavetipswithweaker
Bodyinflated anteriorly, widest at setiger bars (Fig. Ic, d); setae ofparapodia in mid-
9, tapering greatly after setiger 12 to well body generally slightly longer than those of
defined tail; color in alcohol white, setae anteriorandposteriorparapodia.Notosetae
clear;bodypapillaeminute(18-24nmlong), and neurosetae similarwithin parapodium,
clavate, sparsely coveringdorsum and ven- with 3-7 capillaries in eachbundle, varying
trum,moreabundantonparapodiawithad- in basal width (3.5-8.8 fxm) and length
mm
ditional 2-3 larger papillae (0.1-0.4 (about 0.5 to almost 2 times body width).
long) on presetal and/or postsetal lips (Fig. Anusterminal; noindicationofanalcirri.
1c, d); mucouscoatorencrustedsandgrains Variation. —Paratypes approximately
absent. same size and numbers of setigers as ho-
Prostomiumroundeddorsally,ill-defined lotype, generally poorly preserved. Body
anteriorly merging into oral tube; eye-spots widest over setigers 6-9. Head region more
absent(Fig. la). Oral tubecylindrical, mus- extended(i.e., cephalichoodretracted)than
cularwith pairofinnerdorsal lips arranged inholotype,exposingsmoothposteriorbuc-
in sagittal plane, separated by deep medial cal region. B1-B3 usually absent or dam-
groove (Fig. lb). Palpal scars anterolateral aged; B4, B5 absent, branchialscarsdifficult
to prostomium (Fig. la, b). Cephalic hood to discern. Non-type specimen with B4
helmet-like dorsally, low and collar-like present, foliaceous, similar in length to cla-
ventrally, extending anteriorly to branchial vate-cirriformtype; onepalppresent,weak-
membrane (Fig. la). Branchial membrane lygrooved, extendingjustbeyondoraltube.
ridge-like, convoluted laterally, extending i^^m^air/c^.—Since Hartman (1978) con-
across dorsum behind prostomium poste- sideredthisspeciestoresembleHesionidae,
riorly (Fig. la, b). Branchiae, 5 pairs, ar- her terminology and interpretation of cer-
ranged as follows (B4 and B5 absent in ho- tainhead-endcharactersreflectedthatopin-
lotype, arrangement inferred by scars): Bl ion. For example, she considered the first
arising laterally from anterior end ofbran- four segments to be achaetous, with seg-
chial membrane; B2 arising dorsolaterally ments 1-3 each having a pair oftentacular
686 PROCEEDINGSOFTHEBIOLOGICALSOCIETYOFWASHINGTON
Fig. 1. Helmetophorusrankini:a, Holotype, head-end, lateralview(B1, B2 illustratedfrom othermaterial;
B4,B5 absent, scarsonlyvisible);b. Diagrammaticrepresentationofhead-end,frontalview(B4, B5 ofleft-side
not shown); c, Paratype, left parapodium 6, posterior view; d, Paratype, left parapodium 15, anterior view.
Abbreviations:B1-B5 = branchiae;Bm =branchialmembrane;Ch =cephalichood; Dl =dorsallip;Ot=oral
tube; Pr = prostomium; Ps = palpal scar. All scalebarsin mm.
VOLUME 104, NUMBER4 687
cirri and segment 4 being long and neck- 1900 and 1904-1905.-Memoirs ofthe Muse-
like. These so-calledsegmentsareherecon- um ofComparativeZoology, Harvard48.
Fauchald, K. 1972. Benthic polychaetous annelids
sidered to be a part ofthe buccal apparatus
from deep water offwestern Mexico and adja-
(i.e.,pre-segmental),andhertentacularcirri centareasin the eastern Pacific Ocean.—Allan
areinterpretedasbranchiae. Hartmanover- Hancock Monographs in Marine Biology 7:1-
looked the branchial scars ofthe posterior 575.
2 pairs ofbranchiae (B4, B5). . 1977. Thepolychaeteworms.Definitionsand
Thereremain somequestions concerning keystotheorders, familiesandgenera.Natural
History Museum ofLos Angeles County, Los
the origin and function ofthe branchial ap- Angeles, 188 pp.
pendages in this species. Branchiae 4 and 5 George,J.D.,&G.Hartmann-Schroder. 1985. Poly-
may not be homologous with B1-B3 be- chaetes: British Amphinomida, Spintherida &
cause the latter arise from the branchial Eunicida. Keysand notes forthe identification
membrane and are clavate-cirriform in ofthe species. Pp. 1-221 in D. M. Kermack&
R. S. K. Barnes, eds.. Synopses ofthe British
shape, whereas B4 andB5 ariseposteriorto faunaNo. 32.E.J.Brill,Dr.W. Backhuys,Lei-
thebranchial membrane and B4, atleast, is den.
foliaceous. None of the material had B5 Haase,P. 1915. BorealeundarktischeChloraemiden.
present and the shape of this structure is Wissenschaftliche Meeresuntersuchungen Ab-
unknown. However, as flabelligerids may teilungKiel 17:169-228 [not seen].
Hartman, O. 1967. Polychaetous annelids collected
have 2 different types ofbranchial append- bytheUSNSEltaninandStatenIslandcruises,
ages (e.g., Diplocirrus species), forthe pres- chiefly from Antarctic Seas.—Allan Hancock
ent all 5 pairs are tentatively considered to Monographsin Marine Biology 2:1-387.
bebranchiae. Aphylogeneticrevisionofthe . 1978. Polychaeta from the Weddell Sea
family may serve to clarify this point. quadrant, Antarctica. Paper 4. Pp. 125-223 in
D.L. Pawson,ed..BiologyoftheAntarcticseas
VI. Antarctic Research Series 26.
Acknowledgments Mcintosh,W.C. 1885. ReportontheAnnelidaPoly-
chaeta collectedby H.M.S. 'Challenger' during
ThispaperwascompletedusingthePost- the years 1873-1876.—Challenger Reports 12:
doctoral Fellowship ofCJG atthe National 1-554.
Museum ofNatural History, Smithsonian Saint-Joseph, M. le Baron de. 1894. Les Annelides
PolychetesdescotesdeDinard. Pt3.—Annales
Institution.
des Sciences Naturelles. Zoologie et Paleonto-
logie 7(17):l-395.
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