Table Of ContentPROC. BIOL. SOC. WASH.
107(1), 1994, pp. 151-163
PSEUDOCYCLOPS LAKSHMI, A NEW SPECIES
(PSEUDOCYCLOPIDAE: CALANOIDA: COPEPODA)
FROM THE LACCADIVES, INDIA
P. Haridas, M. Madhupratap, and S. Ohtsuka
Abstract.—Pseudocydopslakshmi, newspecies,isdescribedfromtheKadmat
and Agatti atolls of the Laccadives, India, along with its dimorphic males.
Characters separating the new species from the rest ofits congeners are dis-
cussed. This species is epibenthic and emerges in large numbers into the water
column at night.
The hyperbenthic calanoid copepod ge- satus from the Indian Ocean was reported
nusPseudocydopsGiesbrecht, 1893 atpres- but not illustrated by Thompson & Scott
ent consists of 29 species described from (1903); there remains the possibility that
shallow waters of the Atlantic and Indo- not all ofits records are correct. Similarly,
Pacific regions (Brady 1872; Brady & Rob- P. australis Nicholls, 1944a, originally de-
ertson 1873; Giesbrecht 1893; Sars 1903, scribed from South Australia has been re-
1919; Esterly 1911; Gumey 1927; Sewell cordedfrom SouthJapan(Tanaka 1966) al-
1932; NichoUs 1944a, 1944b; Noodt 1958 beit with differences in the structure of
Bowman &Gonzalez 1961; Vervoort 1964 exopods ofantenna and mandibular palp.
Tanaka 1966; Wells 1967; Fosshagen 1968 During investigations on zooplankton of
Por 1968; Dawson 1977; Andronov 1986 the atolls ofthe Laccadive Sea (Madhupra-
Othman&Greenwood 1989;Barr&Ohtsu- tap et al. 1991a, 1991b), an undescribed
ka 1989). Nine species of the genus have species ofPseudocydops was found to be a
hitherto been recorded/described from the dominant calanoid copepod in the night-
Indian Ocean including the Red Sea and timenettowsintheshallowlagoonsofKad-
Suez Canal, viz. P. obtusatus Brady & Rob- mat and Agatti atolls. Although Pseudocy-
ertson, 1873 from the Arabian Sea and Sri dops species are usually distributed near or
Lanka (Thompson & Scott 1903); P. um- on the seabottom, they are often found in
bricatus Giesbrecht, 1893 and P. latens the water column due to their vertical mi-
Gurney, 1927 from the Suez Canal; P. la- gration (e.g., Esterly 1911, Gumey 1927,
tisetosus Sewell, 1932, and P. simplex Sew- Vervoort 1964, Fosshagen 1968, Dawson
ell, 1932 (typelocalitiesofthesetwo species 1977, Othman & Greenwood 1989, Oht-
are not given in Sewell 1932); P. reductus suka unpublished data). The present paper
Nicholls, 1944b, P. gohariNoodt, 1958 and describes both sexes ofthe new species of
P. steinitziPor, 1968 fromtheRed Sea, and Pseudocydops including the apparently di-
P. xiphophorus Wells, 1967 from Mozam- morphic males.
bique. Their occurrences so far are known
onlyfromtypelocalitiesexceptP. obtusatus
Pseudocydops lakshmi, new species
which is recorded broadly from the North
Figs. 1-7
Atlantic Ocean, the Mediterranean Sea and
the Indian Ocean (see Thompson & Scott Marer/a/.—Specimens were collected in
1903, Rose 1933, Vervoort 1964, Othman surface hauls at night using a square net
& Greenwood 1989). Pseudocydops obtu- (mesh width 200 /um) from Agatti on 10-
PROCEEDINGSOFTHE BIOLOGICALSOCIETY OFWASHINGTON
152
VOLUME NUMBER
107, 1 153
Fig.2. Pseudocyclopslakshmi.Female:SEMphotomicrographs.A.Urosomedorsalview;B.Urosomeventral
view; C. Distal margin ofgenital double-somite dorsal view; D. Genital double-somite ventral view. All scale
bars = 10^m.
Fig. 1. Pseudocyclopslakshmi, Female:A.Habitus,dorsal;B.Habituslateral;C.Urosome.Male:D.Habitus,
dorsal; E. Habitus lateral; F. Urosome.
154 PROCEEDINGSOFTHE BIOLOGICALSOCIETY OFWASHINGTON
Fig. 3. Pseudocyclopslakshmi. Female; A. Antennule. Male: B. Rightantennule.
1 1 Dec 1988 andfromKadmatbetween 14- withapairofminutesensilla. Urosome(Fig.
16 Dec 1988. The morphological terminol- IC) 4-segmented, distal margins of first 2
ogy follows Huys & Boxshall (1991). The somites lamellar. Genital double-somite
urosomesoffemalesofthenewspecieswere largest, as long as following 2 somites com-
examined with a Scanning Electron Micro- bined and covered with numerous minute
scope (SEM-JEOLJSM T-20). Alltypes are prominences (Fig. 2A, C). Gonopores and
deposited at the Indian Ocean Biological copulatory pores paired, closed offby oper-
Centre (lOBC), Cochin. culum-like leg 6 (Fig. 2B, D). Second and
Types.—WoloXypc: Female, total length third urosomal somites with subterminal
0.90 mm, lOBC 0405-08-46-1992. Allo- transverse row of minute spinules; third
type: Male, morph "A"-IOBC 0406-08- urosomal somite produced posterodorsally
46-1992. Paratypes: 10 females & 1 1 males into 2 triangular processes reaching beyond
(6 morph "A" and 5 morph "B"), lOBC midlength ofcaudal ramus (Fig. 2A); anal
0407-08-46-1992plustwofemalesandfour somite small and telescoped into third uro-
malesdissectedandmountedonglassslides some somite. Caudal ramus with serrate
IOBC-0408-08-46-1992. posterior margin dorsomedially and
1
Description.—¥tvc\2i\t. Body (Fig. lA, B) bluntly pointed processventromediallyand
mm
0.86-0.95 in total length (average 0.90 with 1 dorsal, 4 terminal and 1 outer sub-
mm, n = 13). Prosome oval in dorsal view, terminal setae.
cephalosome separate from first pedigerous Antennule (Fig. 3A) 21-segmented, not
somite, fourth and fifth pedigerous somites quite reaching to posterior end ofcephalo-
completely separate, posteriorcomeroffifth some; first segment with 3 large aesthetascs
pedigerous somite smoothly rounded, and 1 1 setae; fourthandfifthandeighteenth
reaching to one-third length ofgenital dou- and nineteenth segments partly fused; ter-
ble-somite. Rostrum pointed, triangular. minal segment with one aesthetasc. Anten-
VOLUME 107, NUMBER 1 155
005 mm
I )
Fig. 4. Pseudocyclopslakshmi. Female: A. Antenna; B. Mandible; C. Maxillule; D. Maxilliped.
na (Fig. 4A) basis with seta on inner distal having 1 seta, seventh segment with 1 me-
comer;endopod3-segmented, firstsegment dial and 4 terminal setae. Mandible (Fig.
with 2 setae at midlength of inner margin 4B)gnathobasewith 8 bluntteeth;basiswith
and subterminal patch ofminute spinules, 2 inner setae and patch of minute promi-
second segment with 5 inner marginal and nences subterminally; endopod 2-segment-
4 terminal setae, third segment bearing 7 ed, first segment small, having 4 inner ter-
setae terminally and 4 rows ofspinules; ex- minal setae, second segment tapering
opod 7-segmented, third to fifth segments proximally, with 1 terminal setae; exopod
incompletely fused, first 6 segments each 4-segmented, first 3 segments each bearing
156 PROCEEDINGSOFTHE BIOLOGICALSOCIETYOFWASHINGTON
0-05mm
Fig. 5. Pseudocyclopslakshmi, Male: A. Morph B maxilla; B. Morph A maxilla.
inner seta, terminal segments carrying 3 se- setae along inner margin; coxal and 2 basal
tae. Maxillule (Fig. 4C) well developed; enditeshaving 3, 4and 5 setae respectively;
praecoxal arthrite with 5 setae on posterior coxal epipodite furnished with 9 setae of
surface and 1 weak and 8 stout spine-like unequal lengths; basal exite having short
VOLUME 107, NUMBER 1 157
single seta; endopod 2-segmented, first seg- mm (average 0.83 mm, n = 10) and that of
mentbearing 5 middle and 5 terminal setae morph B 0.85-0.95 mm (average 0.90 mm,
along inner margin, second segment with 6 n = 10), prosome ofboth morphs similar
terminal setae; exopod 1-segmented, with to female (Fig. ID, E).
1 1 setae. Praecoxal and coxal endites of Urosome (Fig. IF) 5-segmented, covered
maxilla (Fig. 5B, female maxilla similar to with minute prominences as in the female;
morphAofmale)having6, 3, 3 and 3 setae first 3 somites with finely striated posterior
respectively;basiscompletelyfiisedwithfirst marginasinfemale; 2triangulardorsalpro-
endopod segment to form allobasis, fur- cesses of fourth somite reaching to distal
nished with 7 setae; endopod 3-segmented, endofcaudalramus; analsomitetelescoped
first to third segments having 2, 2 and 3 into fourth somite. Caudal ramus with ser-
setaerespectively. Maxilliped(Fig.4D)syn- rate dorsomedial margin and ventromedial
coxal endites with 1, 2, 3 and 3 setae re- blunt process.
spectively; allobasis with 3 medial and 2 Right antennule (Fig. 3B) 18-segmented,
terminal setae along inner margin; second geniculatebetween 14thand 15thsegments;
tofifthendopodsegmentseachwith4 setae. first segment with 3 large aesthetascs and 3
Legs 1—4 (Fig. 6A-D) each with 3-seg- rowsofminutespinules; seventhandeighth
mented rami, all bearing numerous minute segments fused or separate; 14th segment
spinulesonbothanteriorandposteriorsur- with sinuous process along whole length of
faces. Exopod segments 1 and2with 1 seta, anterior margin; 16th segment produced
exopod segment 3 with 5 setaeexceptin leg distally into triangular process reaching
1 (4 setae), endopod segments 1 and 2 with midlength of 17th segment; terminal seg-
1 and2setaerespectively,endopodsegment ment with one aesthetasc. Left antennule
3 with 8 setae except in legs 1 (6 setae) and 21-segmented; fourth and fifth, and eigh-
4 (7 setae). Outer distal comers of second teenth and nineteenth segments incom-
endopod segments of legs 2-A each pro- pletely fused as in female antennule.
duced into bifid process; distal comers of Antenna, mandible, maxillule, maxilli-
third endopod segments oflegs 1-4 acutely ped and legs 1-4 ofboth morphs similar to
produced. Second exopod segment ofleg 1 those ofthe female.
withbulbousprocessonouterdistalcomer; Maxillaofmorph B(Fig. 5A)abouttwice
terminalspinesofthirdexopodsegmentsof as long as that ofmorph A (Fig. 5B); 2 ser-
legs 1-4 elongate but not flanged. rate setae on basis (indicated by small ar-
Leg 5 (Fig. 6E). Basis with outer subter- rows) much stouter in morph B than in
minal seta on posterior surface; endopod morph A; seta on second endopod segment
3-segmented, first segment having a small (indicatedbylargearrow)longerandstouter
outerspinule, firstandsecondsegmentwith in morph B than in morph A.
innerterminal seta, third segment having 1 Legs 5 ofbothmorphs(Fig. 7A-I)similar
inner, 1 outer 2 terminal setae; exopod to each other except being slightly smaller
3-segmented, third segment with 4 flanged in morph A. Right leg: coxa and intercoxal
spines and 4 inner setae. scleritefused;basisseparatefromcoxa,with
Male: Dimorphism was observed only in 1 seta on posterior surface; endopod (Fig.
males. The differences between the two 7A, D, E, F) 1-segmented with small ter-
morphs are found in body length and max- minal spinulesandminutesurface spinules,
illa. In particular, the two morphs differ in usually without terminal seta; exopod
the size ofmaxilla (see Fig. 5A, B). In this 2-segmented, first segment with stout,
paper, males with small and large maxillae flangedterminalspine,secondsegmentwith
are referred to as morphs A and B respec- 3 processes, outerlong, thick, and medially
tively. Body length ofmorph A 0.81-0.85 curved, middle small at base ofouter pro-
158 PROCEEDINGSOFTHE BIOLOGICALSOCIETY OFWASHINGTON
Fig. 6. Pseudocyclopslakshmi, Female: A. Leg 1; B. Leg 2; C. Leg 3; D. Leg4; E. Leg 5.
VOLUME NUMBER 159
107, 1
Fig. 7. Pseudocyclopslakshmi. Maleleg5:A.Posteriorview(leftexopodsegment2omitted);B. Leftexopod
segment 2; C. Left endopod; D. Anteriorview; E-F. Rightendopod variability; G-L Pointed process on basis
ofleftleg showingvariability in shape.
160 PROCEEDINGSOFTHEBIOLOGICALSOCIETY OFWASHINGTON
cess, inner slender and recurved appearing 1968, P. mathewsoni Fosshagen, 1968, P.
as chela. Left leg: coxa incompletely fused reductus, P. rubrocinctus Bowman & Gon-
with basis on both surfaces; basis covered zalez, 1961 and P. Steinitze although their
with minute surface prominences, with antennules and antennae are more ad-
elongate, pointed process originating from vanced.
anterior surface (Fig. 7A, D, G, H, I) and 1 The present new species, however, has
setaonposteriorsurface; endopod(Fig. 7A, several advanced morphological characters
C) 1-segmented, with numerous surface present on the urosome, leg 1 and female
prominencesand 5 plumoseterminal setae; leg 5. The urosome is covered with minute
exopod 2-segmented; first segment with prominences, the second exopod segment
outer terminal flanged spine; second seg- ofleg 1 has an outer bulbous process, and
ment (Fig. 7B) spoon-shaped, complex and there are 4 setae on the third endopod seg-
membranous, proximal lobe oblong with 2 mentofthefemale leg 5 (6 setaeinP. kulai,
hemispherical hyalineprocesses originating P. lepidotus Barr 8l Ohtsuka, 1989, P. ma-
from medial margin and 2 terminal pro- thewsoni, P. rubrocinctus, and P. steinitzi).
cesses, 2 outerprocessesattachedontoout- Theurosomewithnumerousminuteprom-
ermargin;proximalprocessrod-shapedwith inences appears to be unique to the new
bulbous projection and short seta at base species although P. lepidotus has foliaceous
and distal process more or less napiform scalesontheurosome. Thebulbousprocess
with subterminal cleft. on the second exopod segment of leg 1 is
Variation.—Segment fusion pattern is known in P. australis and P. gohari; some
variable in right antennule of morph A congeners have a well developed process
male—seventh and eighth segments com- distal to the outer spine on the second ex-
pletely or incompletely fused. Right endo- opod segment of leg 1 different in shape
pod ofleg 5 ofmorph B male has none or from that of P. lakshmi. Pseudocydops
1 terminalseta.Theprocessoriginatingfrom lakshmiseems to be most closely related to
left basis ofleg 5 ofmorph A male is vari- P. australisfrom SouthAustraliaandJapan
able in shape, smoothly taperingdistally or and P. gohari from the Red Sea in having
having a knob medially (Fig. 7G-I). 3-segmented endopod of the female leg 5
Etymology.—This new species is named with 4 setae on the terminal segment and a
after goddess "Lakshmi" (Hindu mytholo- bulbous process on the second exopod seg-
gy) who symbolizes abundance and wealth. ment ofleg 1. In particular, the structures
Asmentionedearlier,thisspeciesisthemost ofleg5 ofbothsexesofP. lakshmiresemble
abundant calanoid copepod in the two la- those ofP. gohari. The leg 5 of female P.
goons. reductus from the Red Sea also shows sim-
Discussion.—The new species lakshmi is ilarity to that offemale P. lakshmi, but Ni-
one ofthe most primitive species ofthe ge- choll's (1944b) description is too incom-
nus Pseudocydops, having 5 separate pe- plete to compare the two in detail.
digerous somites, 21-segmented female an- Pseudocydops lakshmi is distinguishable
tennule and 7-segmented antenna exopod; from P. australis, P. gohari, and P. reductus
it has an outer basal spine on leg 3, in metasome, urosome, and legs 1 and 5 in
3-segmentedendopodinleg 5 offemaleand addition to antennule and antenna. Cepha-
5 plumose setaeontheleftendopodofmale losome and the first pedigerous somite are
leg 5. Such primitive characters as 5 sepa- separate in P. lakshmi and P. australis, but
rate pedigerous somites, 3-segmented en- fused in P. gohari. Male P. gohari has 8, 8
dopod of female leg 5 and 5 setae on left and 6 well-developed posterodorsal pro-
endopod ofmale leg 5 are found also in P. cesses on the second, third and fourth uro-
australis, P. gohari, P. kulai Othman & somal somites respectively; theterminal se-
Greenwood, 1989, P. lerneri Fosshagen, taeonthecaudalramusareextremelyswollen.
