A new species of Syrticola Willems

12 Pages·1993·4.4 MB·

by  Rony Huys

Bull. nat. Hist. Mus. (Zool.)59(1): 83-94 Issued24June 1993
A &
new species of Syrticola Willems Claeys,
1982 (Copepoda: Harpacticoida) from Japan
with notes on the type species
RONY HUYS
DepartmentofZoology TheNaturalHistory Museum, CromwellRoad, London SW75BD
,
SUSUMU OHTSUKA
Fisheries Laboratory, Hiroshima University, 1294 Takehara-cho, Takehara, Hiroshima 725, Japan
CONTENTS
Introduction 83
Materialsand Methods 83
Descriptions 84
FamilyCylindropsyllidae Sars, 1909 84
SubfamilyLeptopontiinae Lang, 1948 84
SyrticolaWillems& Claeys, 1982 85
Syrticolaintermediussp nov 85
.
SyrticolaflandricusWillems& Claeys, 1982 92
Remarks 92
Discussion 93
Keytospecies 93
Acknowledgements 93
References 94
Synopsis. A newspeciesofSyrticola Willems& Claeys, 1982 (Harpacticoida: Cylindropsyllidae) isdescribed from
Okinawa, Japan. Morphological notes on the type species S. flandricus Willems & Claeys, 1982 and a key to the
species are given. The inadequately described S. trispinosus A. Scott, 1896 is ranked as species inquirenda. The
diagnosisofthegenusisamendedanditspositionin theCylindropsyllidae re-assessed. BothsexesofS. intermedins
sp. nov. were found to be infested by early parthenogenetic female stages of an as yet undescribed genus of
Tantulocarida.
INTRODUCTION In the course ofa surveyofthe sandy bottom copepods off
Nagannu Island, Okinawa (Ryukyu Archipelago) by one of
us (S.O.), several interstitial harpacticoids were found to be
Tkhnoewnin,tearsstiistitahlathoafrpmaocstticeoaisdtfAasuinaancoofunJtarpieasn. iTshveerpayucpiotoyrloyf Tinhfiesstpeadpewrithdestcarnitbuelsocaarnideawnssp(eHcuiyessoeft Sayir,tiicnolpareWpialrlaetmiosn)&.
data on marine interstitial species stands in marked contrast Claeys (Cylindropsyllidae) based on two specimens thatwere
with the number of studies on subterranean copepods pro- parasitized by parthenogenetic females of an as yet unde-
duced by workers like Miura and Takashi Ito. In fact, with scribed tantulocarid.
the possible exception of Microsetella norvegica (Boeck,
1864) only 11 genuinely interstitial harpacticoids have been
recorded from marine and brackish water habitats in Japan
MATERIALS AND METHODS
(Table 1) and the majority of these was described by the
latter author's namesake, the late Tatsunori Ito, whose
activities were mainly focussed on the fauna from Hokkaido
SpecimensofSyrticola intermediussp. nov. were collected by
inthe north and the Bonin Islands in the southeast. The only dredging of a sandy bottom off Nagannu Island, Okinawa,
ottaihneerdiinnftohremaptaipoenrsonofmKieksuocphsiam(1m9i7c0,h1a9r7p2a)ctaincodidKsikuischcion&- SOohuttshukJaa)paonn (926A°pr1i4l' 1N9,921.27T°he32'drEe,dgdeep(tmhou4t6.h49armea;:l5e0g.cSm.
Yokota (1984), reporting on species from Lake Hinuma, a wide x 15 cm high; mesh size 5 mm) was towed along the
brackish lagoon near the central east coast of the Japanese bottomataspeedof2knotsbytheT/VToyoshio-maruofthe
mainland.
Hiroshima University for about 5 minutes. Copepods were
84 R. HUYS AND S. OHTSUKA
Table1 Interstitialharpacticoidcopepodsreportedfrom marine localitiesinJapan.
Species Locality Reference
ECTINOSOMATIDAE
Microsetellanorvegica (Boeck, 1864) Hokkaido Ito (1968)
Arenosetellabidenta Ito, 1972 Hokkaido Ito (1972, 1984)
Noodtiellasp. Hokkaido Ito (1984)
DARCYTHOMPSONIIDAE
Leptocarisbrevicornis (van Douwe, 1904) LakeHinuma1 Kikuchi& Yokota
(1984)
PARAMESOCHRIDAE
Paramesochrasp. Hokkaido ltd (1984)
LEPTASTACIDAE
Cerconeotesjaponicus(Ito, 1968) Hokkaido Ito (1968, 1984)
ParaleptastacusunisetosusIto, 1972 Hokkaido Ito (1972, 1984)
CYLINDROPSYLLIDAE
Arenopontiaishikariana Ito, 1968 Hokkaido Ito (1968, 1984)
ArenopontiasakagamiiIto, 1978 Bonin Islands Ito (1978)
StenocarisintermediaIto, 1972 Hokkaido Ito (1972)
PsammopsyllusimamuraiKikuchi, 1972 Lake Hinuma1 Kikuchi (1972)
PARASTENOCARIDIDAE
Parastenocarishinumaensis Kikuchi, 1970 Lake Hinuma1 Kikuchi (1970)
1 Brackishlagoon.
fixed and preserved in 10% neutralized formalin/sea-water. species provisionally placed in Notopontia but subsequently
Females of S. flandricus Willems & Claeys, 1982 were allocated toSyrticola (Bodiou & Colomines, 1986; Willemset
collected by the senior authorin different localities along the ai, 1987). However, none of these authors has formally
coast of The Netherlands in the course of the biological assigned either of these genera to any of the subfamilies of
monitoring programme BIOMON. All specimens have been the Cylindropsyllidae recognized at that time. The only
deposited in the collections ofThe Natural History Museum, attempt was that by Bodiou (1977) who suggested that
London. Notopontiaisclosestto Evansula (Cylindropsyllinae) butto a
Specimens were dissected in lactic acid and the dissected certain extent is also related to Arenopontia Kunz and
partswere placed in lactophenol mountingmedium. Prepara- LeptopontiaT. Scott (Leptopontiinae).
tions were sealed with glyceel (Gurr®, BDH Chemicals Ltd, Lang (1948) subdivided the family into the Cylindropsylli-
Poole, England). All drawings have been prepared using a nae, Leptastacinae and Leptopontiinae and a fourth subfam-
camera lucida on a Leitz Diaplan differential interference ily, the Psammopsyllinae, was added by Krishnaswamy
contrast microscope. The descriptive terminology is adopted (1956). Recently, the Leptastacinae hasbeenupgradedtofull
from Huys & Boxshall (1991). Abbreviations used in the text familystatus (Huys, 1993). The diagnosticsexualdimorphism
are: P1-P6, first to sixth thoracopod. displayed on thoracopods 2 and 3 by all genera of the
Cylindropsyllinae excludes Notopontia and Syrticola from
this subfamily since their swimming leg sexual dimorphism is
only slightly developed (and therefore might well have been
DESCRIPTIONS
overlooked in Notopontia for which it has been recorded as
being completely absent). A detailed comparison with the
Family Cylindropsyllidae Leptopontiinae, currently encompassing Arenopontia,
Pararenopontia Bodiou & Colomines and Leptopontia,
reveals a suite of apomorphic characters supporting a sister-
Subfamily Leptopontiinae Lang, 1948
group relationship between Leptopontia and the Notopontia-
The genus Syrticola was established by Willems & Claeys Syrticola lineage. These characters include: (i) anal
(1982)toaccommodatethetype speciesS.flandricusWillems operculum drawn out into spinous process(es); (ii) outer
& Claeys, 1982 and Tetragoniceps trispinosus A. Scott, 1896. distal corner of caudal ramus produced into backwardly
Previously, the latter species had been considered 'species directed spinous process; (iii) first antennulary segment (
incertcC in the genus EvansulaT. Scott and thusplacedin the extremely elongated, much longer than second; (iv) mandib-
subfamilyCylindropsyllinae (Lang, 1948). Theclose relation- ular gnathobase stylet-like with teeth along one side; (v)
ship between Syrticola and Notopontia Bodiou noted by distalexopodsegmentPI with3armatureelements(proximal
Willems & Claeys (1982) was already hinted at by Bodiou outer spine lost); (vi) middle exopod segment PI without
(1977) who recognized a certain resemblance between T. outerspine (inSyrticolaandNotopontiathe middle anddistal
trispinosus and N. stephaniae Bodiou, 1977, and indirectly segment are fused or have failed to separate); (vii) apical
also by Mielke (1982) who described (?) N. galapagoensis, a spines ofdistalexopod segments P3-P4setiform; (viii) sexual
NEW SPECIES OFSYRTICOLA FROM JAPAN 85
dimorphism endopod P3 involving fusion of distal spine to Anal somite (Figs. 1A-B; 4A; 5A-B) with dorsal opercu-
segment; (ix) P5 exopodwith 3 elementsin bothsexes. There lum drawn out into median, posteriorly directed, spike;
islittleevidencethatArenopontiaandPararenopontiashare a processabout aslongas analsomite proper;ventralposterior
close relationship with this core group, however pending a margin spinulose medially.
revision of these genera it is preferable to retain them in the Caudal rami (Figs. 4A; 5A-B) divergent; outer distal
Leptopontiinae. cornerdrawn out intobackwardlydirected, acutelyrecurved,
spinous process; with 7 setae; seta I minute, setae II and III
Syrticola Willems & Claeys, 1982 located anterior to seta I, seta IV tiny and located between
spinous process and large seta V, seta VII long and tri-
Diagnosis (amended). Leptopontiinae. Body cylindrical, articulate at base, seta VI minute.
but not particularly vermiform. Hyaline frill of all body Antennule (Fig. 2A) 7-segmented, articulating on a small
somites incised. Antennule 6- or 7-segmented in 9- Maxilla pedestal as in the male (Fig. 6B); slender, anteriorly directed
with one syncoxal endite. Midventral spinous process ante- (Fig. 1A); first segment extremely elongate, about 4times as
rior to intercoxal sclerite of PI. PI exopod 2-segmented. long as maximum width, with 1 short seta distally; aesthetasc
Distal segment PI endopodwith 1 geniculate seta and 1 claw. on fourth segment fused basally to long seta; distal 2 setae of
Distal segment P3-P4 exopods with 1 outer spine. P2-P4 last segment fused basally. All setae bare; setal formula: [1,
endopods 1-segmented in 9> P3 endopod 1- or 2-segmented 8, 3,2+ae, 1,2,9].
and sexually dimorphic in cf. P5 with fused baseoendopod Antenna (Figs. 2B-D). Coxasmall, not ornamented. Basis
and exopod in both sexes; endopodal lobe drawn out into and proximal endopod segment fused to form allobasis,
triangularprocesswith0-1 seta,exopodal lobe atuberclewith originalsegmentation marked byinternalchitinousribanteri-
3 elements. Genital apertures not fused in 9- Anal opercu- orlyandincomplete suture line posteriorlynearexopod;basis
lum with a series of small spinous processes or one large with serrate seta located on inner lateral surface; exopod
medianspike. Caudalramusseta III inserted proximal toseta small, 1-segmented, with 1 small, apical seta; free endopod
V. articulating with allobasis at right angle (Fig. IB), lateral
TYPESPECIES. Syrticolaflandricus Willems & Claeys, 1982 margin with 2spines, distal margin with 1 pinnate spine and4
geniculate setae, the largest of which is fused basally with
Other species. S. trispinosus (A. Scott, 1896), S. galapa- vestigial seta and bearing coarse spinule at about midway.
goensis (Mielke, 1982), 5. mediterraneus Willemsetal., 1987, Labrum (Fig. 5C)aventrallyprojected, elongate, membra-
5. intermedius sp. nov. nous outgrowth, distinctly tapering distally. Paragnaths small
membranous lobes.
Syrticola intermedius sp. nov. (Figs. 1—4, 5A-C, 6) Mandible (Figs. 2E-F) with conspicuous coxa, drawn out
Material examined. Holotype 9 dissected on 8 slides, to form a slender, stylet-like gnathobase bearing small teeth
and a long serrate seta near the apex. Palp elongate,
deposited underreg. no. 1992.1075. Paratype a" dissected on
2-segmented; proximal segment representing basis, slightly
6slides, deposited under reg. no. 1992.1076. Drawings based
on the paratype are Figs. 2E-F, 4D-F, 5A-C, 6A-G; all sigmoid, swollen in distal half, with 1 seta and spinular row;
distal segment representing endopod, with 2 lateral and 3
otherswere drawn from the holotype 9
• apical setae.
Female. Body length measured from tip of rostrum to Maxillule (Fig. 2G). Praecoxa with large, cylindrical arth-
posterior margin ofcaudal rami 485 um (Figs. 1A-B). Maxi- rite bearing 2 anterior surface setae and 6 setae along the
mumwidth 75 [im measured at rearmargin ofcephalothorax. distal margin; coxal endite with 2 setae; palp representing
Integument pitted. Pleural areas of cephalothorax not well fused basis and rami; exopod, endopod, proximal and distal
developed so that appendages are clearly exposed in lateral basal endites represented by 1, 2, 2 and 3 setae, respectively.
aspect (Fig. IB). Posterior margin of body somites (except Maxilla (Fig. 2H) reduced, 2-segmented. Syncoxa with
cephalothorax and anal somite) fringed dorsally and laterally single endite bearing unipinnate seta and conspicuous
with finely incised hyaline frill; this frill also present ventrally aesthetasc-like structure representing modified seta with chi-
on genital double-somite and abdominal somites (Figs. IB, tinizeddorsal margin andtubularmembranouspartventrally;
4A-B). Abdominal somites also with transverse spinular row exit ofmaxillary gland discernible in proximal half. Allobasis
in anterior half which is usually concealed beneath the drawn out into pinnate claw bearing serrate seta at its base.
hyaline frill ofthe preceding somite as shown in Fig. 5A. No trace ofendopod.
Rostrum triangular, with 2 delicate sensillae (as in male, Maxilliped (Fig. 4F) subchelate. Syncoxa and basiswithout
Fig. 6B). armature but with 3 spinular rows each. Endopod repre-
Genital double-somite (Fig. 4B) about as long as wide; sented bystrongclawbearingtinyspinulesalongdistal halfof
original segmentation not marked by any external or internal inner margin; an accessory setule is located at the base ofthe
cuticularstructure; anteriormarginwith 2 transverse spinular claw.
rows. Genital apertures located in anterior quarter ofgenital PI (Fig. 3A). Praecoxa a small sclerite located around the
double-somite, closely set together but separate and each outer lateral margin of the limb base. Intercoxal sclerite a
closed off by small operculum derived from sixth leg; no minute rounded plate. Coxa with spinular row. Basis with
armature observed but posterior margin of operculum with inner and outer basal seta and with spinules at middle distal
minute spinous processes and a circular scar at the outer margin. Exopod 2-segmented, proximal segment with blunt
distalcorner(probablyindicatinginsertionsite oflongsetaas spine bearing long setules, distal segment with 2 geniculate
in 5. flandricus, cfr. Fig. 5G). Copulatory pore located far setae and 1 unipinnate spine. Endopod 2-segmented, elon-
anteriorly between genital apertures (arrowed in Fig. 4B). gate, prehensile; proximal segment about twice as long as
Seminal receptacles not confirmed. Paired widely separated exopod, with serrate inner seta near proximal margin; distal
secretory pores at about 2/5 distance from anterior margin. segment with 1 geniculate seta, 1 short claw and a patch of
86 R. HUYSANDS. OHTSUKA
Fig. 1 Syrticolaintermediussp. nov. female. A, Habitus, dorsal; B,same, lateral.
NEW SPECIES OFSYRTICOLA FROM JAPAN 87
20 jj
g.2 Syrticolaintermediussp. nov. female. A,Antennule; B, antenna, innerlateralview;C, distalendofantennaryendopod,outerlateral
view;D, antennaryexopod,outerlateralview;G, maxillule; H, maxilla. Male. E, mandible; F, Mandible,gnathobase.
R. HUYSAND S. OHTSUKA
\\
\
\
i
11
I
1
Fig.3 Syrticolaintermediussp. nov. female. A, PI, anterior;B, P2, anterior; C, P3, anterior; D, P4, anterior.
NEW SPECIES OFSYRTICOLA FROM JAPAN 89
l»iif^
4 Syrticolaintermedinssp. nov. female. A, Urosome,ventral; B, genitaldouble-somite,ventral;C,P5, anterior. Male. D, P5, anterior;
fg.
E,sixthpairoflegs;F, maxilliped. [ArrowsinC-Eindicatingvestigialseta;copulatorypore arrowedinB.]
90 R. HUYSANDS. OHTSUKA
^:;^:-X;;:^il;m
Fig 5 Svrftco/amtewze^sp. nov. male. A, Analsomite andleftcaudalramus, dorsal; B, analsomiteandrightcaudalramus ventral- C
labrum, anterior. Femaleofundescribed tantulocaridan. D, Cephalicshield, dorsal; E, same,lateral. Syrticolaflandricusfemale F P5
anterior;G, genitaldouble-somite,ventral;H, analoperculumandleftcaudalramus, dorsal.
91
ig.6 Syrticolaintermediussp. nov. male. A, Habitus, dorsal; B, rostrumandantennule,dorsal;C, antennule,segments3and4, anterior
[armatureofthesesegmentsomitted;segment4stippled]; D, antennularysegment3, anterior; E, antennularysegment4, anterior;F,
proximalpartofantennularysegment5,anterior; G, P3endopod, anterior.
92 R. HUYS AND S. OHTSUKA
finespinules. Adistinct, ventrallydirected, spinousprocessis Etymology. The species name is derived from the Latin
located at the ventral midline between the maxillipedal inter, meaning between, and medius, meaning middle, and
syncoxae and the coxae ofthe first leg (Fig. 3A). refers to the intermediate position between S. galapagoensis
P2-P4 (Figs. 3B-D) with 3-segmented exopods and and the European species ofthe genus.
1-segmented endopods. Intercoxal sclerites small, rectangu-
lar, bare (Fig. 3C). Spines of distal exopodal segment elon- Syrticolaflandricus Willems & Claeys, 1982 (Figs.
gate and slender in P3 and P4. Inner seta of P2 endopod 5F-H)
serrate and typically recurved (Fig. 3B). Inner margin of
endopod P3 with serrate seta and vestigial seta represented Materialexamined. 3 5$ fromoffWalcheren,The Neth-
bysetule (seeinsetFig. 3C). Distalspinesofendopodpinnate erlands, southern North Sea, 51° 57'25" N, 02° 40'45" E,
in P2-P3, bare in P4. Armature formula as follows: depth 44.5 m, coarse sandy sediment, 08 May 1991, coll. R.
Huys. One $ in alcohol deposited under reg. no. 1992.1077.
The description given by Willems & Claeys (1982) is
coxa basis exopodsegment endopodsegment detailed and therefore only a few corrections to the original
1 2 3 1 2 figures are noted here.
Antenna. The exopod possesses only one seta as in S.
intermedius and 5. galapagoensis. The oblique suture line has
PPI2 00--00 11--10 11--00;; 11-,02;,0 1,11,0 00,-111;,1 0,1,1 probablybeen mistaken for the lateral seta (compare Fig. 2D
P3 0-0 1-0 1-0; 1-0; 1,1,1 0,1,2 with Fig. 2B in Willems & Claeys (1982)), and it is conceiv-
P4 0-0 1-0 1-0; 1-0; 1,1,1 0,1,1 able that the same misinterpretation applies for S. mediterra-
neus (cf. Willems etai, 1987: Fig. 3A).
Fifth legs (Figs. 4A, C) closely set together, no intercoxal Mandible. The basis bears only one seta; the supernumer-
sclerite. Baseoendopod and exopod fused to form a single aryproximal 'setae'figuredbyWillems& Claeysare partofa
platewith 2secretoryporesand4armature elements in total; transverse row of long spinules running around the lateral
endopodal lobe represented by long, triangular, spinous margin ofthe basis.
process without setae but with tiny spinules along proximal Maxillule. The arthrite ofthe praecoxa has 6 marginal and
outer margin and on posterior surface; exopod presumably 2 surface setae, the coxal endite 2 setae and the distribution
represented by weakly developed process bearing outer pin- pattern of the palp setae is identical to 5. intermedius (Fig.
nate spine, innerslenderseta and avestigial seta in between. 2G).
Outer basal setaelongate and bare. Maxilliped. The endopodal claw bears an accessory setule
at its base.
Male. Body length measured from tip of rostrum to poste- PI. A seta is located at the inner distal cornerofthe basis.
riormarginofcaudal rami (Fig. 6A) 460 \im. Ornamentation P5. The armature ofthe exopodal lobe consists ofan outer
of body somites generally as in female; genital and first spine, an innerseta and a setule in between (Fig. 5F).
abdominalsomitesseparate, with spinulose hyaline frill each. The genital field is basically the same as in S. intermedius
Sexual dimorphism in antennule, P3 endopod, P5, P6 and in (Fig. 5G).
genital segmentation. Spermatophore not observed.
Antennule (Figs. 6B-F) indistinctly8-segmented, articulat-
ingon asmall pedestal. Relative lengthsoffirst twosegments
REMARKS
asin female. Third and fourth segment (= ancestral segment
XIII) interdigitating as shown in Fig. 6C. Major geniculation
between segments 6 and 7. Segmental fusion pattern: I, Asingle probablyparthenogeneticfemale ofatantulocaridan
II-VIII, IX-XII, XIII, XIV-XVIII, XIX-XX, XXI-XXII,
was found attached to the pleurotergite of the P3-bearing
XXIII-XVIII. Segment 6 with 1 modified flat spine and 1 somite of the holotype 2 of S. intermedius (Fig. 1A). The
eselteumleen,t.seAgrmmeanttur7ewfiotrhmusliam:il[a1r, 9s,pi5n,e2,an4d+ae1,s2t,ub2b,y9]p.innate sdepveecliompemnenist.aboTuhte16l0ar\viaml lpoonsgtcaenpdhailsicat tarnunekarlhyasdtagbeeeonf
P3 endopod (Fig. 6G) 2-segmented. Proximal segment
sloughed already but no differentiating tissue could be
unarmed. Distal segment drawn out into pinnate process
observed inside the sac. The male paratype was also infested
(derived from distal spine in $) with spatulate tip bearing 2 by a parthenogenetic female (Fig. 6A) which was larger
rows of denticles; inner margin with short pinnate seta and
(235 jim) and attached to the pleurotergite of the genital
minute setule. somite. Inside the sac a large number of small eggs of about
P5 (Fig. 4D). Relativeposition, shape andarmature largely 20-25 um in diameter is contained. Both tantulocaridan
similar to female except for the inner exopodal and outer
stages most likely belong to an as yet undescribed species
basalsetabeingdistinctlyshorter. Ornamentationofendopo- which was found to infest harpacticoids belonging to at least
dal lobe also slightly different with fewer spinules along the two other families (Huys et al., in preparation). Since only<
proximal outer margin and tiny spinules along the inner
the head shield (Figs. 5D-E) is left for comparison this;
margin.
identification has to be consideredprovisional.
Sixth pair of legs (Fig. 4E) positioned midventrally, sym-
metrical; inner distal corner with numerous minute spinules
and produced into a small process; armature consisting of
innerstrong spine, outerslender seta and avestigial setule in
between.
Variability. An aberrant left P3 was noticed in the holo-
type $ (Fig. 3C).