The first zoea of
Camptandrium sexdentatum
is described for the first time with a digital image of live zoeas. An ovigerous crab of
C. sexdentatum
was collected at the muddy sand flat in Namhaedo Island on 2 June 2012 and hatched in the laboratory on 6 June 2012. In Camptandriidae, the first zoea of
C. sexdentatum
is distinguished from the first zoeas of
Cleistostoma dilatatum
and
Deiratonotus cristatum
by having no dorsal and lateral carapace spines, an abdomen significantly broadened posteriorly, and a subovoid telson without forks. Especially, the finding of a subovoid telson without forks is the first report in brachyuran zoeas.
INTRODUCTION
Crabs of the Camptandriidae currently include 37 species of 19 genera in the world (
Ng et al., 2008
), of which, three species of three genera have been reported in Korea (
Kim, 1973
;
Kim and Kim, 1997
):
Cleistostoma dilatatum
(
De Haan, 1833
),
Deiratonotus cristatum
(
De Man, 1895
), and
Camptandrium sexdentatum
Stimpson, 1858. They inhabit mudflats between high and low tidal marks. The type genus
Camptandrium
contains only one species,
C. sexdentatum
and has a wide Indo-West Pacific distribution from India, Thailand, Indonesia, China, Japan, to Korea (
Tan and Ng, 1999
). Larvae of
C. dilatatum
and
D. cristatum
have been described by
Kim and Lee (1982)
and
Terada (1979)
; however, those of
C. sexdentatum
are unknown.
In the present study, the first zoeal stage of
C. sexdentatum
is described and illustrated for the first time. Its characteristics are compared with those of other two species of the family.
MATERIALS AND METHODS
On 2 June 2012, an ovigerous crab of
C. sexdentatum
was collected at the muddy sand flat in Namhaedo Island, Gyeongsangnam- do, Korea (34˚49′44.55′′N, 128˚02′12.28′′E). Its zoeas hatched in the laboratory on 6 June 2012 and were preserved in 95% ethanol for examination. Zoeal specimens were dissected using a Leitz zoom stereomicroscope and appendages were examined under a Leitz Laborlux S microscope (Leica, Wetzlar, Germany). Drawings were made with the aid of
camera lucida
. Setal counts and measurements were based on ten specimens. The sequence of the zoeal description is based on the malacostracan somite plan and described from anterior to posterior. Setal armature of appendages was described from proximal to distal segments and in order of endopod to exopod (
Clark et al., 1998
). The long plumose natatory setae of the first and second maxillipeds were drawn truncated. A micrometer was used for zoeal measurements: carapace length (CL) was measured from the anterior margin of the eyes to the most posterior carapace margin. The brachyuran classification follows that of
Ng et al. (2008)
. The remaining zoeas and the spent female were deposited at Silla University, Korea.
RESULTS
-
Order Decapoda Latreille, 1803
-
Family CamptandriidaeStimpson, 1858
-
GenusCamptandriumStimpson, 1858
-
Camptandrium sexdentatumStimpson, 1858
-
First zoea(Figs. 1A,2A-J)
A, Photograph of first zoeas of Camptandrium sexdentatum. Photographs of zoeal abdomen and telson: B, Cleistostoma dilatatum; C, Camptandrium sexdentatum; D, Philyra pisum. Scale bars: A=0.4 mm, B-D=0.1 mm.
Camptandrium sexdentatum, first zoeal stage. A, Lateral view; B, Antennule; C, Antenna; D, Mandibles; E, Maxillule; F, Maxilla; G, First maxilliped; H, Second maxilliped; I, Dorsal view of abdomen and telson; J, Posterior region of telson. Scale bars: A, I=0.1 mm, B-H, J=0.05 mm.
Size: CL 0.35±0.01 mm.
Carapace (
Figs. 1A
,
2A
): Rostral spine extremely short, dorsal and lateral spines absent; 1 pair of posterodorsal setae present; each ventral margin with 1 plumose seta; eyes sessile.
Antennule (
Fig. 2B
): Uniramous; with 2 long aesthetascs and 1 small seta distally.
Antenna (
Fig. 2C
): Protopod spinulate distally, longer than rostral carapace spine; exopod approximately equal length to protopod, simple distally, with 1 submedial seta.
Mandibles (
Fig. 2D
): Asymmetrical.
Maxillule (
Fig. 2E
): Coxal endite with 4 setae; basial endite with 5 setae (4 plumodenticulate); endopod 2-segmented, proximal segment without seta, distal segment with 4 setae.
Maxilla (
Fig. 2F
): Coxal endite bilobed, with 3+3 setae; basial endite bilobed, with 4+5 setae; endopod bilobed, with 2+3 setae; scaphognathite with 3 marginal plumose setae and 1 distal stout process.
First maxilliped (
Fig. 2G
): Coxa with 2 setae; basis with 10 setae arranged 2+2+3+3; endopod 5-segmented, with 2, 2, 1, 2, 5 (1 subterminal+4 terminal) setae; exopod with 4 long plumose natatory setae distally.
Second maxilliped (
Fig. 2H
): Coxa without seta; basis with 3 setae arranged 1+1+1; endopod 3-segmented, with 0, 1, 6 (3 subterminal+3 terminal) setae; exopod as in first maxilliped.
Abdomen (
Figs. 1A, C
,
2A, I
): With 5 somites, significantly broadened posteriorly; somites 2, 3 each with 1 pair of lateral processes; somites 2-5 each with 1 pair of posterodorsal setae; pleopod buds absent.
Telson (
Figs. 1A, C
,
2I, J
): Subovoidal, narrowing posteriorly; fork absent; posterior margin with shallow median cleft and 5+5 processes, which increasing its length towards inside.
Color (
Fig. 1A, C
): Black chromatophores on posterodorsal region of carapace, around mouthparts, on base of each maxilliped, on each abdominal somite, and on posterior region of telson.
DISCUSSION
Based on zoeal descriptions of two species,
Cleistostoma dilatatum
by
Kim and Lee (1982)
and
Deiratonotus cristatum
by
Terada (1979)
,
Ko and Lee (2012)
reported that the zoeas of Camptandriidae could be distinguished from other Korean brachyurans by having the following characteristics: 1) endopods of the maxillule and maxilla each with 0, 4 and 2+3 setae, respectively, 2) basis of the first and second maxillipeds each with 2+2+3+3, 1+1+1 setae, respectively, and 3) short rostral and dorsal carapace spines. In the present study, the zoea of
C. sexdentatum
agrees with their description, except dorsal carapace spine. In respect to other characteristics, such as no lateral carapace spines and a telson without forks, it is significantly different from those of the other two species having lateral carapace spines and telson forks (
Table 1
).
Comparison of the first zoeal characteristics in three species of the Camptandriidae
A subquadrate telson with forks (
Fig. 1B
), as seen in zoeas of
C. dilatatum
and
D. cristatum
, is usually found in brachyuran zoeas. A subovoid telson without forks (
Fig. 1C
) in
C. sexdentatum
is reported for the first time, although, a triangular telson without forks (
Fig. 1D
) is reported in a pinnotherid,
Arcotheres sinensis
(
Shen, 1932
) by
Ko (1991)
and a leucosiid,
Philyra pisum
De Haan, 1841
by
Ko (1996)
.
Long larval spines which increase the surface area are considered to be morphological adaptations to enhance buoyancy (
Calado, 2009
). So, zoeas of the above three species (
C. sexdentatum
,
A. sinensis
, and
P. pisum
) without dorsal and lateral carapace spines might be difficult to stay stationary in turbulent sea water. Therefore, it is considered that zoea of
C. sexdentatum
should be equipped with an abdomen broadened posteriorly and a subovoidal telson for the purpose of buoyancy and swimming.
Calado R
2009
Marine ornamental shrimp: biology, aquaculture and conservation
Wiley-Blackwell
Oxford
1 -
280
Clark PF
,
Calazans D
,
Pohle GW
1998
Accuracy and standardization of brachyuran larval descriptions
Invertebrate Reproduction and Development
33
127 -
144
De Haan W
,
von Siebold PF
1850
1833-1850. Crustacea;Fauna Japonica, sive Descriptio animalium, quae in itinere per Japoniam, jussu et auspiciis superiorum, qui summum in India Batava imperium tenent, suscepto, annis 1823-1830 collegit, notis, observationibus et adumbrationibus illustravit
Lugduni-Batavorum
Leiden
1 -
243
De Man JG
1895
Berichtuber die von Herrn Schiffscapitan Storm zu Atjeh, an den westlichen Kusten von Malakka, Borneo und Celebes sowie in der Java-See gesammelten Decapoden und Stomatopoden. (In 6 parts). Zoologische Jahrbucher, Abtheilung fur Systematik
Geographie und Biologie der Thiere
8
485 -
609
Kim CH
,
Lee HJ
1982
First zoeal stage of Cleistostoma dilatatum De Man and its taxonomic significance
College of Library Science of Pusan National University
34
275 -
262
Kim HS
1973
Anomura, Brachyura. Illustrated encyclopedia of fauna and flora of Korea. Vol. 14
The Ministry of Education of Korea
Seoul
1 -
506
Kim W
,
Kim HS
1997
List of animals in Korea (excluding insects)
Academy Press
Seoul
212 -
223
Ko HS
1991
The First Zoeal Stage of Pinnotheres sinensisShen, 1932(CURSTACEA,BRACHYRA, PINNOTHERIDAE) Reared in the Laboratory
Animal Systematics, Evolution and Diversity
7
(2)
257 -
264
Ko HS
1996
Larval Development of Philyra pisum De Haan, 1841(Crustacea: Decapoda: Leucosiidae)Reared in the Laboratory
Animal Systematics, Evolution and Diversity
12
(2)
91 -
99
Ko HS
,
Lee SH
2012
Invertebrate fauna of Korea. Vol. 21, No. 15. Crabs and zoeas I. Arthropoda: Crustacea: Decapoda: Brachyura: Thoracotremata: Grapsoidea, Ocypodoidea
National Institute of Biological Resources, Ministry of Environment
Incheon
1 -
83
Ng PKL
,
Guinot D
,
Davie PJF
2008
Systema Brachyurorum: Part 1. An annotated checklist of extant brachyuran crabs of the world
Raffles Bulletin of Zoology
17
1 -
286
Shen CJ
1932
The brachyuran crustacea of north China
Zoologica Sinica
9
1 -
320
Stimpson W
1858
Prodromus descriptionis animalium evertebratorum, quae in Expeditione ad Oceanum Pacificum Septentrionalem, a Republica Federata missa, Cadwaladaro Ringgold et Johanne Rodgers Ducibus, observavit et descripsit. Pars V. Crustacea Ocypodoidea
Proceedings of the Academy of Natural Sciences of Philadelphia
10
93 -
110
Tan CGS
,
Ng PKL
1999
A revision of the genus Camptandrium Stimpson, 1858 (Crustacea: Decapoda: Brachyura: Camptandriidae)
The Raffles Bulletin of Zoology
47
193 -
219
Terada M
1979
On the zoea larvae of five crabs of the family Ocypodidae
Zoological Magazine
88
57 -
72