A new Species of Namanereidinae: Namalycastis Glasbyi Sp Nov from Indian Waters

2007·1.9 MB·

by  Olivia T Fernando

)
Journal of the Bombay Natural History Society, 104 (1), Jan-Apr 2007 64-67
A NEW SPECIES OF NAMANEREIDINAE: NAMALYCASTIS GLASBYI SP. NOV.
FROM INDIAN WATERS
1
OliviaJ. Fernando2,3andR. Rajasekaran2,4
'Accepted July 05, 2005
2Centre ofAdvanced Study in Marine Biology, Annamalai University, Parangipettai 608 502, Tamil Nadu, India.
’Email: [email protected], [email protected]
+Email: [email protected]
A new species ofthe Genera Namalycastis. Subfamily Namanereidinae, Family Nereidae, is being described here.
Collections from Gorai creek, Mumbai, included Nereid worms previously undescribed. Namalycastis indica is a
speciesofNamalycastisrecordedmostfrequentlyfromIndia. SubsequentlyN.fauvleihasbeendescribedfromIndian
waters. In addition to this N. abiuma species group has also been observed though not recorded. As N. indica and
N. abiumaresembleeachother,therehasbeensomeconfusionwithregardstotheiroccurrencefromthedifferentareas
studied. The present study records the occurrence ofa new species Namalycastisglasbyi; akey is being provided to
helpdistinguishthedifferentspeciesofNamalycastisoccurringinIndianwaters.
Keywords: Nereidae,Namalycastisglasbyisp.nov.,Mumbai,Namalycastisindica Namalycastisfauveli
,
Hartman(1959)consideredthegenusLycastisSavigny Table 1: Records of distribution of Namalycastis indica
1822ofthesubfamilyNamanereidinaeasasynonymofNereis and N. fauvelialong the Indian coast
Linnaeus 1758andproposedthenameNamalycastistoreplace
it. Characters used to distinguish genus Namalycastis are: SI.No Reference Study area N. indica N. fauveli
presenceofamid-anteriorcleftontheprostomium,twosmall
1. Southern (1921) ChilikaLake X
conicalantennae,twoconspicuous,broadpalpswithdistinct 2. Balasubrahmanyan Vellar X
palpostyle, twopairs oftentacularcirri on eitherside in two (1960)
bundles oftwo tentacles each, ofwhich the longest reaches 3. Ghosh (1963) Thiruchendur X
backwaters
up to the fourth segment and absence of papillae and
4. Soota & Rao (1977) Andaman & X
paragnathsinthepharynx. Dorsalcirrianteriorlyslenderand i
Nicobar islands
small, conical, posteriorly elongated, nearly one and a half 5. Rao (1981) Bytarani estuary X X
times the length ofthe dorsal cirrus ofthe anteriorsegment. 6. Srinivasa Rao & Vashista-Godavari X
ThereducedorlackofnotopodialconditionsofNamanereidinae RamaSarma(1981)
is a unique feature among this group. The presence of both 7. Antony and Vembanad estuary X
Kuttyamma (1983)
notoacicula and neuroacicula in the parapodiaofthe first two 8. Misra etal. (1984) Gangetic delta X
setigersis alsounusual among theNereididae. 9. Misraand Sagar Island X
TheearliestrecordofthisgenusinIndiaisbySouthern Choudhary(1985)
(1921) from Chilika Lake as Lycastis indica. Since then, 10. Misra etal. (1987) Orissa backwaters X
Namalycastis indica has been recorded from several 11. SunderRaj & Pulicat X
Sanjeeva Raj (1987)
estuaries,backwatersfromtheAndamanandNicobarIslands
12. Kalaiselvi and Vellar estuary X
andtheeastandwestcoastoflndia(Table 1).Southern(1921 Ayyakkannu (1986)
also mentions two specimens collected from Cochin (now 13. Rao (1993) Mahanadi X
Kochi backwaters and Garia, lowerWest Bengal, ofwhich 14. Rao (1995) Chilika X X
)
thesinglespecimenfromCochinisdescribedtohaveasingle 15. Misra (1995) HooghlyMalta X X
16. Rao (1998) Bytarani estuary X X
setae anterior to the dorsal aciculum and shorter antennae
17. Rao (1999) Godavari X
andtentacularcirri,thusdifferingfromLycastisindica.Glasby 18. Rao (2001) Godavari X X
(1999)isoftheopinionthatthissinglespecimenfromCochin, 19. Pillai(2001) Cochin backwater X
collected by Southern, may likely be another species,
MATERIALANDMETHODS
N.abiumasp.group.AnotherspeciesdescribedfromBytarani
estuarybyRao(1981)-Namalycastisfauveli-hasalsobeen
frequentlyobservedfromseveralregionsalongtheeastcoast During the present study four specimens ofthe genus
oflndia. (Table 1) Namalycastis were collected from sandy, clayey intertidal
NEW DESCRIPTIONS
Fig. 1: Nemalycastisglasbyi: a. head; b. parapodia of segment 8; c. parapodia of segment 20; d. parapodia of segment 50;
e. parapodia of segment 100; f. parapodia of segment 160; g. jaw piece, ventromedial view; h. neuropodial setae
sediments,about3kmupstreaminGoraicreek,Mumbai.Gorai creek mouth, lies theAkse-Madh coastal strip; the northern
creeksituatedin the suburbsofMumbai (formerly Bombay) bankofthecreekisborderedbyManori village,whichforms
(19° 12' N, 72° 48' E) extends 12 km inland through vast a natural beach. As these specimens were different from the
mangrove mudflatsand low-lying marshy area. Southofthe species of Namalycastis described earlier, more detailed
1 Bombay Nat. Hist. Soc., 104 (1), Jan-Apr 2007 65
.
NEW DESCRIPTIONS
observations were made. aboutearliertaxonomicreferences.
Threeofthefourspecimenswerecomplete;thelargest The present specimens differ from TV. indica by
mm mm
had 289 segments up to 64 long and 1 wide. The presence of nearly coalescent eyes, unjointed dorsal cirrus
longest tentacular cirri reached up to the fifth segment. that is elongated and enlarged in the posterior segments. It
Maximumwidthisatsegment 15afterwhichittapersgradually. alsodiffersfromTV.fauveliinwhichtheanteriorcleftisabsent,
Theprostomiumhasashallowcleftwithanarrowlongitudinal the two pairs ofeyes arranged transversely and presence of
groove extending from tip to mid-posterior ofprostomium. 2-3 subterminalteethinthejaw. ItdiffersfromTV. abiumaby
Eyes are in a straight line at the posterior margin of the the presence of notopodial setae (1-3) up to the mid body
prostomium and nearly coalescent. The proboscis is armed region,in noparticularorder,andbythepresenceofunequal
with a pair ofjaws but lacks paragnaths and papillae. Each number of heterogomph spinigers and falcigers in the
jaw has a distinct terminal tooth, a single subterminal tooth neuropodia.
(Fig.lg)andagroupoffourteethensheathedproximally.The The presence ofa single subterminal tooth in thejaw
presence of a single subterminal tooth distinguishes this and the presence ofnotopodial setaeranging between 1 and
specimen fromall othersoftheTV. abiuma sp. group. 3 in the anterior part ofthe body distinctly separates these
The parapodia are sub-biramous, each carries two specimens from the previously described species and is
2.
acicula. Neuropodial ligule bilobed with superior lobe therefore described here as a new species Namalycastis
papilliform and inferior lobe globular. Notopodial spiniger glasbyi.
startsfromsetiger4-6andvariesinnumberfrom 1-3,extending
up to the 60th segment. Neurosetae are in two fasicles, one Keyto distinguish genusNamalycastis
belowandoneabovetheventralaciculum.Thefasicleabove OBSERVEDFROM INDIANWATERS
theventralaciculum(VA)has8spinigersand5 falcigers;the
fasiclebelow theVAhas 3 spinigersand 8 falcigers. 1 Acicularneuropodialligulebilobed,superiorlobepapilliform.
Joint of the dorsal cirri with cirrophore is indistinct, inferiorlobeglobular 2
—
posteriordorsal cirri nearly three and ahalftimes as long as Acicularneuropodialligulesubconicalorweaklybilobed ... 4
the parapodial lobe. The dorsal cirri increase in length — Antennae small,extendingtotipofpalpaphore 3
posteriorly. On the anteriorsegment it isconical andonly as Antennaesmall, usuallyextendingshortoftipofpalpaphore,
jaw with4-5 subterminalteeth& 3-5 ensheathedproximally
long as the podium, almost double in length 50th segment
N. abiuma sp. group
onwards and nearly fourtimes long at the 160th segment. At
3. Jaw with 4 subterminal teeth, 4 ensheathed proximally
Tthheopuogshtetrhieorreeinsdnothaertliecnugltahtiiosn,fiavesltiigmhetscointsstwriidctthio(nFiisg.prleas-ehn)t. — Jaw with 1 subterminal tooth and 4 ensheathed pTVr.oxaibmiaulmlay
inthe dorsalcirrus. N.glasbyi
4. Jaw with 2-3 subterminal teeth, 2-4 ensheathed proximally,
DISCUSSION heterogomphfalcigerswithbossextremelyprolonged
N.fauveli
—
TV. indicaandTV. abiumasp.grouparesimilarinexternal Jaw with 2-5 subterminal teeth, 3-5 ensheathed proximally,
appearance, and unless setal types and distribution are heterogomphfalcigerswithbossnotprolonged N. indica
examined carefully the two species are very difficult to
separate (Glasby 1999). Glasby is also of the opinion that Habitat; Holotype from a tidal creek nearly 3 km
mostdescriptionsofTV. indicainthetaxonomic literaturefail upstream, salinityunknown.
to give an adequate account of setal type distribution and rIVpelocality:Goraicreek,Mumbai,westcoastofIndia.
therefore it is quite possible that the two species have been Etymology: NamedafterDr.ChristopherJ.Glasbyfor
widelyconfused. DoubtfultaxonomicreferencetoTV. indica hisdetailedstudyofNamanereidinae.
include those ofGhosh (1963), Day (1967) and Sunder Raj
andSanjeevaRaj(1987).Asthereisconsiderabledifficultyin ACKNOWLEDGEMENT
describing the distribution ofsetae, i.e. pre and post supra-
acicular neurosetae, and the pre and post subacicular WethankTheDirector,CASinMarineBiologyandthe
neurosetae,itisnotsurprisingthatthereisconsiderabledoubt authoritiesofAnnamalaiUniversityforfacilitiesprovided.
66 J. Bombay Nat. Hist. Soc., 104 (1), Jan-Apr 2007
NEW DESCRIPTIONS
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