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Crustorhabditis chitwoodi sp. nov.(Nematoda: Rhabditidae): An intertidalspecies from the coast of New South
Wales, Australia, with observations onits ecology and life historyWarwick L. Nicholas
a
a Division of Botany and Zoology , Australian National University ,
Canberra, ACT, 0200, Australia E-mail:
Published online: 30 Mar 2010.
To cite this article: Warwick L. Nicholas (2004) Crustorhabditis chitwoodi sp. nov. (Nematoda:Rhabditidae): An intertidal species from the coast of New South Wales, Australia, with observations
on its ecology and life history, New Zealand Journal of Marine and Freshwater Research, 38:5,
803-808, DOI: 10.1080/00288330.2004.9517279
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8/17/2019 Crustorhabdsaditis Chitwoodi Sp. Nov. (Nematoda Rhabditidae)
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New Zealand Journal
of
Marine
and
Freshwater Research, 2004,
Vol
38Nicholas—Crustorhabditischitwoodisp.n
0 0 2 8 - 8 3 3 0 / 0 4 / 3 8 0 5 - 0 8 0 3
©
T h e
R o y a l S o c i e t y
of
N e w
Z e a l a n d 2 0 0 4
803
rustorhabditis
chitwoodi sp nov.
Nematoda:
Rhabditidae):
an
intertidal
spec ies from the coast of New
South
Wales,
Australia, with observations on its ecology and life history
WAR WICK L. NICHOLAS
Division of Botany and Z oology
Australian National University
Canberra
ACT 0200, Austral ia
email: warwick@webone.com.au
Abstract A new species, Crustorhabditis chit-
woodi ,
w as discovered in nutrient agar plates inocu-
lated with beach sand co llected from an o cean beach
in New South Wales, Austral ia.
The
three other
known species
of
the genus have
all
been found
as
commensal inhabitants
of
ocypodid shore crabs.
It
is suggested that the sand inoculum was seeded w ith
dauer larvae of the nematod e that had been dispersed
by scavenging crabs. The new species is distin-
guished from the three previously described species
by possessing a smaller number of differently ar-
ranged bursal papillae, eight rather than
10. The
species
is
amphim ictic, oviparous,
and
produces
abundant dauer larvae
in
culture, which can be sus-
tained indefinitely
on sea
water nutrient agar
in
which
it
feeds
on
associated bacteria.
K e y w o r d s
Crustorhabditis;
Brach yura; in tertidal
beach; marine; nematode
M0 4115; Online publication date
24
November 2004
Received 1 June 2004; accepted
9
September 2004
INTRODUCTION
The name Crustorhabditis was given by Sudhaus
(1974) to an ew subgenus of Rhabditidae to accom-
modate three species that are intimately associated
with beach-inhabi t ing ocypodid crabs . The new
species, described in this paper, was c ollected from
a sandy beach
in
south-eastern A ustralia awa y from
crabs
and can
reproduce
in the
laboratory
in
their
absence.
The
ghost crab,
Ocypode cardimana is
found o n the same beach, but with burrows near the
high t ide mark. Sudhaus (1974) described
C
riemanni, the type species, from nem atodes cultured
in the laboratory from specimens isolated from the
mouthparts and branchia l chamber of Ocypode
kuhlii, where it apparently lives as a saprobiont. T he
crab cam e from a beach at Kikambala, K enya, E ast
Afr ica . Most Rhabdi t idae
are
bacteria-feeding
terrestrial nematodes and, al though
a
number
of
bacteria-feeding Rhad itidae are comm only found in
the intert idal zone, only
the
three previously
described species
of
Crustorhabd itis
are
known
to
be closely associated with crabs.
Chitwood (1935) originally described
C. ocypo-
dis, which
he
found
on the
eggs
of O albicans
inhabit ing
a
sandy beach
in
North Carol ina ,
as
Parasitorhabditis ocypodis, but
later changed
the
n a me to Rhab ditis ocypodis (Chitwood, 1951).
Sudhaus (1974) redescribed the species from fixed
material obtained by R iemann from O. albicans from
a sandy Caribbean beach in Colum bia, South
Am erica. Sudhaus also redescribed
C. scanica,
origi-
nally named
Rhabdit is scanica by
Allgén (1949),
from specimens found between the mo uthparts of the
same beach crab that hosted
C. riemanni
when
the
crab was collected
at
Kikambala
in
Kenya.
Crustorhabditis is morphologically very close to
the subgenus M esorhabditis Osche, 1952. Osche's
mon ograph sets out to review the morphology of all
the then described species of Rhabd itis, but over-
looked Allgén's description of R. scanica. Osche
assigned
R. ocypodis
Chitwood, 1935,
to R habdit is
(Mesorhabditis) ocypodis.
Dougherty (1955),
in a
nomenclatorial review
of
the Rhabd it idae Örley,
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804
New Zealand Journal of Marine and Freshwater Research, 2004, Vol. 38
1880, assigned both R. scanica and R. ocypodis to
the subgenus M esorhabditis . In a mono graph on the
taxonomy of the Rhabdi t idae, Andràssy (1983)
raised O sche's (1952) subgenera to generic rank.
METHODS
A culture of C. chitwoodi sp. nov. was established
fortuitously when a small amo unt of beach sand was
scattered on a 5 0 cm agar plate. The medium was 2
agar in sea water enriched w ith 5 m g Na
2
S iO
3
,5 mg
K
2
HPO
4
and 5 mg Fe(NH
4
)
2
(S O
4
)
2
per litre.
The intention had been to culture algae and
diatoms as part of ongoing studies of the dietary
habits of nematodes, but instead brown clumps of
glutinous bacteria-forming rosettes of cocci formed,
later to be dispersed and fed upon by the nematodes.
Some nematod es were transferred to 0.5 bacterio-
logical nutrient agar in sea water. Dense cultures and
many gen erations of the nem atodes were ma intained
by serial subculture on the same nutrient agar
medium. At this agar concentration the nematodes
move freely through the medium and are not
restricted to the surface.
Individual larval nematodes, or small groups of
eggs,
or newly hatched larvae were transferred to
small 5 cm closed agar plates and incubated at 20°C
to study the life cycle. All the nematodes fed on
bacteria transferred with the nema tode inoculum.
Nematode type specimens were fixed in 5
formalin plus 10 acetic acid for 24 h then washed
in distilled water and transferred to 5 aqueo us
glycerol. Water was evaporated in an oven at 40°C
and the nem atod es were then transferred with a fine
needle to anhydrous glycerol on glass slides and a
cover sl ip was supported by fine glass beads
(ballatini) and ringed with Glyceel (G urr). M easure-
ments were made of nematodes after fixation and
mounting in this way.
SYSTEMATICS
A diagnosis of genus Crustorhabditis is taken from
Andràssy's (1983) taxonomic monograph on the
Rha bditoidea, w hich places the genus hierarchically
in the Rhabd itidae, and M esorhabditinae. The body
is relatively large, 0.8 to 4 mm long, cuticle with
transverse annules and fine longitudinal striae. Head
slightly offset, lips well separated with small rod -like
papillae, amphids very small, on lateral lips. Stoma
(buccal cavity) 1.5 to 2 times as long as head
diameter. Cheilostom not cuticularised, promesos-
tom tubular with parallel walls; metastom consisting
of three hemispherical swellings, each bearing two
minute den ticles; pharyngeal sleave do es not invest
promesostom . Pharygeal corpus swollen, muscular,
isthmus long and non -muscular, nerve ring encloses
isthmus posteriorly, metacorpus with cuticular valve,
muscular, cardia small tripartite enclosed by anterior
intestine. Female gonad unpaired prodelphic, vulva
far posterior, close to anu s, tail conical. Ma le gona d
unpaired, spicules strong, the posterior two thirds
fused, bursa pelloderean, open anteriorly, anterior
half with crenulated margin, 10 pairs of genital
papillae present, two of them lying prean al, tail very
short, phasmids open close to anus.
Sudhaus & Fitch (2001) give a very detai led
review of the genus
Crustorhabditis
based on
C .
ocypodis
and
C. r iemanni,
but ignore
C. scanica.
Crustorhabditis
is morphologically very close to
Mesorhabdit is
and two of the three previously
described species were transferred by Sudhaus
(1974) to the newly created genus Crustorhabditis.
In distinguishing the two genera, Sudhaus draws
attention to their association with beach-inhabiting
ocypodid crabs, their large size, the crenulated
anterior bursal velum, the strong spicules fused for
the posterior two thirds of their length (in
Mesor-
habditis
usually fused for less than two thirds of their
length).
Crustorhabditis scanica
is smaller than the
other two species and the dependen ce of this species
on ocypod id crabs needs qualification.
Type species
Crustorhabditis chitwoodi sp. nov.
Material examined
Holotype male, AN IC slide 32 specimen
4 1:
Allo-
type female, slide 32 specimen 4 2; 9 paratype m ales:
slide 33 specimen 45, slide 35 specimens
5 0 - 5 3 ,
slide 36 specimens 5 7-5 9; slide 37 specimen 6 1; 9
paratype females: slide 32 specimens 43–44, slide
33 specimen 4 6, slide 34 specimens 4 7–49, slide 36
specimen 60, slide 37 specimens
6 2 - 6 3 .
All type
specimens taken from same agar plate culture
inocula ted with beach sand from the Brou lee beach,
New South Wales on 4 April 2004. Type specimens
are deposited in the Austral ian National Insect
Collection, Nematode Collection (ANIC), CSIRO
Entomology, G.P.O Box 1700, Canberra , ACT,
Australia.
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Nicholas— Crustorhabdit is chitwoodi sp. nov
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Description
Measurements in µm are given in Table 1, see also
Fig. 1.
Holotype male Body predominantely cylindrical,
tapered towards the head and truncated abruptly at
the posterior end; cuticle annulated; six slightly
offset lips bearing papilliform outer labial and
cephalic papillae, inner labial papillae not visible.
Cheilostom not cuticularised, Promesostom cylin-
drical, parallel sided, strongly cuticularised; a nterior
pharynx muscular, expanded to form muscular
corpus, followed by non-m uscular narrower isthmus,
then expanded to form muscular metacorpus;
metacorpus with semilunar cuticular valves,
terminating in tripart i te short muscular cardia.
Straight intest ine, anteriorly encloses cardia,
terminates in short narrower rectum , about level with
spicule capitulum, that terminates in cloaca. Single
testis, vas deferens ventral to gut, opens ven trally to
cloaca. Paired, long strongly built spicules, with
distinct capitulum, grooved shaft, fused for posterior
two thirds of their length, with sharp straight tip.
Bursa open a nteriorly, velum crenulated for anterior
half eight paired bursal rays, two short pair
pre-cloacal, one pair at level of cloacal opening,
paired group of three post-cloacal then two more
pairs slightly separated from their group of three, at
extreme posterior of bursal velum, beside very short
tail, triangular from dorsal view, no terminal notch
in velum (Fig 1).
Five paratype m ales do not differ significantly
from holotype.
Allotype female Essentially similar to male apart
from sexual organs and po sterior end of body. Single
ovary, uterus and oviduct ventral to gut, oviduct
terminating in a posterior vulva, close to but anterior
to an us. Oviduct with two uncleaved eggs. Tail initially
conical but drawn out into a terminal filament.
The excretory system described by Sudhaus &
Fitch (2001) was not identified in any of the types
or paratypes. A small perturbation of the cuticle
posterior to the nerve ring observed in several
specimens may be the excretory pore, but no
terminal cuticular duct was evident so the identity
of the cuticular structure is doubtful. Perhaps the
excretory system is less prominent in specimens
cultured in a saline medium than in typical terrestrial
rhabditids.
Table
Measurements of type specimens of Crustorhabdit is chitwoodi sp. nov. All measurements in µm.
Type
Length
Buccal cavity
Prostom
Pharynx
Head to corpus
Corpus length
Head to nerve ring
Head to bulb
Bulb length
Head to intestine
Head to gonad
Spicule length
Gubernaculum
Bursa length
Head to vulva
Vulva to anus
Head to anus
Tail length
Max. width
Width at vulva
Width at anus
de M an's a
de M an's b
de M an's c
de M an's V
Holo.
Male
970
22
17
194
98
41
149
182
34
223
317
67
48
53
95 3
17
43
23
23
5.0
40
Males
Mean
1020
23
17
194
93
35
144
174
35
21 8
32 8
62
37
58
989
24
43
23
24
5.3
4 2
n = 10
SD
57
1.66
1.48
9.6
8.61
3.6
10.4
10
4.0
10.4
31
4.6
6.4
5.6
56
2.3
4.9
2.07
2.91
0.23
2.1
Range
970-1084
19-24
15-19
196-202
77-101
31–41
134-158
161-188
30–43
199-226
283-379
53-67
26–48
53-70
944-1065
2 4 -3 6
36–48
2 0 -2 6
2 1 -3 0
5.0-5.6
37-57
Allo.
Female
1090
22
17
196
91
41
1581
185
41
22 6
468
960
41
1001
89
43
43
26
25
5.6
12.3
88
Females
Mean
1086
22 2
18
193
93
3.5
158
180
38
218
34 9
961
49
946
89
40
36
27
28
5.6
12.3
89
n= 10
SD
64
3.0
2.4
10.9
4.0
8.84
10.4
2.9
12.4
41
58
4.5
8.62
67
3.1
6.2
3.1
5.63
4.61
0.24
1.15
1.8
Range
–10841090
17-24
17-22
178-213
86-96
29–41
132-136
161-195
35–41
197-228
332-467
883-990
4 3 - 5 3
869-1039
82-101
36–48
30-46
19-41
2 2 -3 4
5.2-5.9
9.7-13.1
86-89
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New Zealand Journal of Marine and Freshwater Research, 2004, Vol. 38
50ftm
X
Fig. 1 Crustorhabdit is sp. nov.
50 nm A, head and pharyngeal region; B,
head and buccal cavity; C, hind
end of female in lateral view; D,
hind end of male in lateral view;
E, hind end of male in dorsal view.
chitwoodi
riemanni
scanica
ocypodis
Fig . 2 Com parison of the bursal
region and bursal papillae of all
four known species of the genus
Crustorhabdit is. C. riemanni, C.
ocypodis,
and
C. scanica
from
Sudhaus (1974); C. chitwoodi, n.
sp .
original. Drawin gs not to same
scale.
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Nicholas— Crustorhabdit is chitwoodi sp. nov
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Dauer larvae, 536-78 7 µm long 21- 24 µm wide,
accumulate in cultures. These are a non-growing
dispersive stage in the life cycle. In common with
other Rhabdit idae, these dauer larvae retain the
cuticle of the second instar, the lips and lumen of the
alimentary canal are closed, but they retain m otility.
Differential diagnosis
Significant differences between C. chitwoodi sp .
nov.,
C. r iemanni, C . ocypodis ,
an d
C. scanica
are
listed in Table 2.
C . r iemanni
an d
C. ocypodis
are
much larger than the other two species, which are
of comparable size. De M an 's ratios of pharyngeal
length to body length,
b ,
and tail length to body
length, c, as well as the ratio of the distance b etween
the vulva and an us to tail length and the absolute tail
length are greater in the former two, probably related
to their greater size. De Man's rat ios are not
independent of body length. C. scanica has shorter
spicules than any of the other three species.
C .
scanica
an d
C. chitwoodi,
sp. nov. are more alike
than the other two. However, the most significant
difference between the four species is the difference
in the number and disposition of the bursal papillae
(Fig. 2). Unlike the other species with 10 pairs, C .
chitwoodi sp. nov. has only 8 pairs. Baird (2001)
shows that in the rather closely related Caeno-
rhabditis briggsae the bursal papillae are a good
indicator of species, although some variation can
occur in strains.
Type locality
Mid-tide level on a sandy beach at Broulee on the
South East Coast of New South Wales, Australia,
La titu de 35º55¢ , Lon gitu de 150º9¢ .
Etymology
The specific epithet nam ed in hono ur of the greatest
nematologist and the describer of
Crustorhabditis
ocypodis .
Reproductive biology
Crustorhabditis chitwoodi sp. nov. is amphimictic,
with approximately equal numbers of male and
female progeny. Females are normally oviparous,
but sometimes eggs hatch in utero and the larvae
devour the mother, i.e., endotokia matricida. Chen
& Caswell-Chen (2003) show that in the related
rhabditid
Caenorhab ditis elegans
this behaviour is
an adaptive response to failing food resources. In the
absence of ma les, females die with several unhatched
eggs
in utero.
Protandrous hermaphrodi t i sm,
comm on in some rhabditids, has not been observed.
The generation time at 20°C is c. 7 days.
Ecology
Crustorhabditis ocypodis was recovered from the
eggs of the shore crab
Ocypode albicans
in North
Carolina in North Am erica by Chitwood (1935) and
again from the branchial chamber of the same
species from Columbia in South America
(Rieman n, 1970).
C. riemanni
has been found in the
branchial chamber and between the mouth parts of
the shore crab Ocypode kuhlii in Ken ya, East Africa,
together with C. scanica. How ever, C. chitwoodi sp.
nov. was not found in direct association with crabs
when it was recovered from sand at mid-tide level,
although
Ocypode cardimana
occurs on the same
beach clo se to the high tide mark. Con sequently this
species is not totally restricted in its distribution to
the immed iate presence of crab s. It can multiply for
Table 2
Com parison of significant taxono mic measurements of three previously described species of
Crustorhah bdit is
an d
C . chitwoodi
sp. nov. All measurements in µm.
Species:
Sex:
Body length
Vulva-anus/tail
Tail length
Spicules length
spicule fused
Bursal formula
d eM a n s ' a
de Ma n's b
de Ma n's c
C. riemanii
Male
1895-2820
0.96
27-54
53-62
66
2 .2 .6= 10
16.5-21.8
6.5-9.1
39.2-64.7
Female
2422-3890
91-158
14.5-23
7.9-11.8
19.6-35.8
C. ocypodis
Male
2015-2380
0.68
24-30
65-71
69
2.1.7 = 10
26.7–40.4
6.1-7.4
71.1-98.5
Female
2 4 2 2 3 8 9 2 1 5 – 2 3 8
101-162
25.4-38.9
6.8-8.7
14.2-17.8
C. scanica
Male
7 8 5 - 1 1 7 0
17-26
38–48
54
2.8 = 10
15.0-22.8
4 . 0 - 6 . 5
31 .4-49 .3
Female
857-1516
0.56
8 3 - 1 2 5
15.0-22.816
6.1-7.46.8
8.7-16.4
C .
chit
Male
970-1084
24-36
53-67
57-60
2.1.3.2 = 8
21-30
5.0-5.6
37.3-57
woodi
Female
950-1090
0.40-0.63
82-101
22-34
5.2-5.9
8.7-1
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New Zealand Journal of Marine and Freshwater Research, 2004, Vol. 38
many generations on nutrient agar, feeding on
associated bacteria.
The dependence of C. scanica for reproduction
on the presence of crabs is uncertain. Schuurmans
Stekhoven (1943) reported Rhabdit is monhystera,
which seems from its description to be a synonym
for
C. scanica,
from sand together with the macro-
algae
Codium
and
Caulerpa
in the Mediterranean.
According to Sudhaus (1974), Allgén (1934)
reported a single male as
Rhab ditis marina
with the
bursal papilla formula of 2/8 so that this specimen
was in all probability C. scanica. Allgén (1949),
again according to Sudhaus (1974), described C .
scanica as a new species from a single male derived
from marine algae. Sudhaus (1974) equates the
single female figured by Gerlach (1953) from c oastal
ground water in Madagascar as
C scanica,
but its
identi ty is by no means certain. In summary,
although
C. scanica
has been found in the mouth
parts of ocypode crabs it has also been found in the
absence of crabs. Sudhaus suggests its dauer larvae
may have been dispersed by c rabs.
Although
C. chitwoodi
sp. nov. was not found in
the proximity of crabs, ocypode crabs do inhabit the
beach from which it was found. It is not a comm on
inhabitant of the beach m eiofauna bec ause it has not
previously been found in studies of this and neigh-
bouring beaches during several years of sampling
(Nicholas 200 1). The m ost likely explanation is that
Ocypode cardimana
crabs scavenge at night at low
tide on the beach and disperse dauer larvae, as
Sudhaus (1974) suggests, and though these are
capable of feeding and reproducing on bacteria, the
habitat does not facilitate sustained reproduction
without direct association with ocypode crabs. It
would be interesting to examine a number of the
local ocypodid crabs for nem atodes, but the author
sees no prospect of doing so in the near future.
REFERENCES
Allgén, C. 1949: Uber einiger sudschwedische Brack-
wasser und Eardnematoden.
Kunglia Fysiogra-
fiska Säliskkapets i Lund Förhandlingar19: 1—19.
Andràssy, I. 1983: A taxonomic review of the suborder
Rhabditina (Nematoda: Secernentia). Edit ions de
l Office de la Re sea rch e Scientifiqu e et Tec h-
nique outra-mer. Paris. Pp 1-240.
Baird, S. E. 2001: Strain specific variation in the pattern
of caudal papillae in
Caenorhabdit is briggsae
(Nematoda: Rhabditidae); implications for spe-
cies identification. Nematology 3: 373-376 .
Chen, J.; Caswell-Chen, E.
2003:
W hy
Caenorhabdit is
elegans adults sacrifice their bodies to progeny.
Nematology 5: 641-645.
Chitwood, B . G. 1935: Nema todes parasitic in, and asso-
ciated with, Crustacea, and description of some
new species and a new variety.
Proceedings of
the Helminthological Society of Washington 2:
93-96 .
Chitwood, B. G. 1961: North American marine nema-
todes.
Texas Journal of Science 3:
617-672.
Dougherty, E. C. 1955: The genera and species of the
subfamily Rhabditinae Micoletzky, 1922 (Nema-
toda):
a nom enclatorial analysis-including an ad-
dendum on the composit ion of the family
Rhabditidae Örley, 1880. Journal o f Helminthol-
ogy 29:
105-152.
Gerlach, S. A. 1953: Recherches sur la faune des eaux
interstitielles de Mad agascar.
M émoires de l Institut
scientifique de M adagascar Series A 8:
73-86 .
Nicholas, W. L. 2001: Seasonal variations in nematode
assemblages on an Australian ocean beach; the
effect of heavy seas and unusually high tides.
Hydrobiologia 464: 127-26.
Osche, G. 1952: Systematik und Phylogenie der Gatung
Rhabditis
(Nematoda).
Zoologische Jahbücher
(Systematik) 81:
190-280.
Riemanni, F. 1970: Das Keimenlückensustem von
Krebsen as lebensraum der Meiofauna, mit
Beschreibung freilebender Nematoden aus
karibichen amphibish lebenden Decapoden.
Veröffentl ichungen Insti tuts für Mee resforschung
in Bremerhaven 12: 413–428.
Schuurmans Stekhoven, J. H. Jr. 1943: Freilebende ma-
rine Nematoden des Mittlemeeres. IV. Freilebende
marine Nematodender Fischereigeregründe bei
Alexandreien.
Zoologische Jahbücher (Syste-
matik) 76:
417–465.
Sudhaus, W. 1974: Nematoden (insbesondere Rhab-
ditiden) des Strandanwurfs un ihre Beziiehungen
zu Krebsen. F auist isch-Ökologisch Mittei lungen
4: 365–400.
Sudha us, W. 1974: Zur Systematik, Verbreitung, Öko logie
und Biologie neuer und wenig bekannter Rhab-
ditiden (Nematoden) 2. Teil. Part II. Zoologische
Jahbücher (Systematik) 101: 417–465.
Sudhaus, W. Fitch 2001: Comparative studies on the
phylogeny and systematics of the Rhabditidae
(Nematoda). Journal of Nematology 33: 1-70.