Leucosia galantua sp. nov. found in Western Australia and northern Papua New Guinea is described and figured. The relationships with other species are discussed

Ovaere, A.

Open Marine Archive

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BULLETIN DE L'INSTITUT ROYAL DES SCIENCES NATURELLES DE BELGIQUE, BIOLOGlE, 58: 95-98, 1988 
BIOLOGlE, 58: 95-98, 1988 BULLETIN VAN HET KONlNKLIJK BELGISCH lNSTITUUT VOOR NATUURWETENSCHAPPEN, 
A new species of the genus Leucosia from Australia and Papua New Guinea 
(Crustacea, Brachyura) * 
by A.A. OV AERE 
Abstract 
Leucosia galantua sp. nov. found in Western Australia and northern Papua 
New Guinea is described and figured. The relationships with other species 
are discussed. 
Key-words: Brachyura, Leucosia, taxonomy, new species, Australia, 
Papua New Guinea. 
Resume 
Leucosia galantua sp. nov. trouvee en Australie occidentale et en Papouasie 
Nouvelle-Guinee est decrite et figuree. Les rapports avec des especes 
voisines sont discutes. 
Mots-clefs : Brachyoures, Leucosia, taxonomie, nouvelle espece, Australie, 
Papouasie Nouvelle-Guinee. 
Introduction 
In an earlier study (Ov AERE, 1987) on Leucosia angulata 
(RATHBUN, 1911) it has been suggested that the specimen 
WAM 227-60 from Maud Landing, Western Australia, 
described by TYNDALE-BiscoE and GEORGE, 1962 belongs 
to a separate species. The study of this interesting specimen 
and of an additional specimen from northern Papua New 
Guinea and the comparison with five specimens of L. 
angulata (RATHBUN, 1911) in the collections of the 
Koninklijk Belgisch Instituut voor Natuurwetenschappen 
(Brussels), confirmed this opinion. Specimen W AM 227-
60 is chosen as the holotype of Leucosia galantua sp. nov. 
and is deposited in the Western Australian Museum, Perth. 
The other material mentioned is deposited in the collections 
of the Koninklijk Belgisch Instituut voor Natuurweten-
schappen, Brussels. 
* Leopold ill Biological Station, Laing Island, Contribution no. 178. 
Systematic account 
Order DECAPODA LATREILLE, 1803 
Infraorder BRACHYURA LATREILLE, 1803 
Family LEUCOSIIDAE SAMOUELLE, 1819 
Genus Leucosia WEBER, 1795 
SYNONYMY 
L eucosia galantua sp. nov. 
(Figs. 1-3) 
Leucosia angulata. - TYNDALE-BtscoE & GEORGE, 1962 : p. 77-80, 
pl. 1, fig. 3, pl. 2, fig. 3. [Non (RATHBUN, 1911)] 
MATERIAL EXAMINED 
A. Holotype : 
An intact adult female (c.!. 15.7 mm; c. b. 15.5 mm), W AM 
227-60, Western Australia, Maud Landing, dredged at 10 
fathoms (approx. 18.3 m) on sand, weed and rock, leg. 
Mr. R.D. RoYcE on the "Davena" during the Bernice P. 
Bishop Museum of Hawaii Expedition to Western Austra-
lia, 
20 Mai 1960. 
B. Paratype : 
A young female (c.!. 11.1 mm, c.b. 10.3 mm), B.C. 1168, 
Papua New Guinea, Hansa Bay (Madang Province), Laing 
Island, dredged on sandy bottom at - 19 to - 20 m, leg. : 
team of Prof. J. BouiLLON, 23 December 1979. 
TYPE LOCALITY 
Western Australia, Maud Landing, 23°12'S-ll3°45 'E. 
DERIVATION OF NAME 
Anagram of angulata, because the species was originally 
refen ed to as Leucosia angulata (RATHBUN, 1911) by TYN-
DALE-BtscoE & GEORGE, 1962. 
96 A.A. OV AERE 
DIAGNOSIS 
Carapace slightly longer than wide; antero-lateral margins 
of the carapace angulate due to the projection of the hepatic 
margin; anterior margin of merus of chelipeds with large 
pearl-like tubercles; thoracic sinus with a row of tubercles, 
the two anteriormost being large and pearl-shaped. 
DESCRIPTION 
(based on the holotype, unless otherwise stated) 
Measurements : 
Adult female WAM 227-60 (holotype), carapace length 
15.7 rnm, carapace breadth 15.5 rnm, cheliped length 22.0 
rnm; juvenile female B.C. 1168, carapace length 11.1 rnm, 
carapace breadth 10:3 rnm, cheliped length 14.4 mm. 
Carapace: 
A little longer than wide; high in the middle; scattered 
hairs on the upper surface of the carapace, becoming more 
dense on the true postero-lateral margins, though not form-
ing a strip of fur (those hairs are absent in the specimen 
from Papua New Guinea); front moderately prominent, 
rounded, weekly quadrilobate in the adult female holotype, 
bilobate in the young female; antero-lateral margin milled, 
with a pronounced rounded projection of the hepatic angle; 
hepatic region slightly elevated; antero-lateral margin 
forming a re-entering angle with the rounded lateral epi-
branchial angle; lateral epibranchial angle milled; true post-
ero-lateral margin (in the holotype) with a higher density 
of hairs than the rest of the dorsal surface of the carapace; 
epirneral edge moderately broad, milled, beginning at the 
basis of the first pair of walking legs, continuous and 
forming rounded angles with the posterior margin; poste-
rior margin milled, convex; a tooth in the middle of the 
intestinal region (as well in holotype as paratype). 
Thoracic sinus : 
Anterior part deep, anteriorly defined by the strongly over-
hanging posterior margin of the pterygostomian region, dor-
sally defined by the overhanging lateral epibranchial angle; 
2-3 large pearly tubercles in its anterior part followed by 
a row of smaller tubercles above the basis of the chelipeds; 
lower margin of the sinus finely milled; filled with long 
hairs, especially in its anterior and superior parts. 
M outhframe : 
As figured; third sternite with a rounded tooth on its antero-
lateral side. 
Chelipeds: 
Moderately long, 1.3 (young female) - 1.4 (holotype) times 
the carapace length; merus with a dense fur proximally; 
anterior margin of the merus with 2-3 large pearly tubercles 
in the median portion and smaller rounded tubercles in the 
proximal and distal portion; posterior margin of mems with 
a double row of tubercles fused to 3 upstanding oval tuber-
cles in the median portion; lower margin with a triangular 
cluster of rounded tubercles; carpus with a row of small 
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tubercles on the outer and inner upper margins; length of 
palm and fingers almost equal; immovable finger with a 
sharp cutting edge and a tooth at one fourth of its length 
(this tooth being absent in the young female). 
Walking legs: 
Merus of the first and second pair with two dorsal and 
two ventral rows of granules; merus of the third and fourth 
pair with a single dorsal and a double ventral row of 
granules (granules worn in the holotype, clearly visible in 
the paratype); carpopodites rounded ventrally, keeled dor-
sally; propodi keeled dorsally and ventrally; dactyli long. 
Female abdomen : 
Three pieces visible, second segment free; third to sixth 
segment fused into a strongly vaulted plate; telson some-
what longer than wide, rounded anteriorly. 
Colours of specimens preserved in alcool: 
Ground-colour ivory white, mottled with brown-grey on 
the upper parts, conspicious orange brown spot on the 
posterior margin above the first walking legs; spots of the 
same colour distributed on the abdomen and the underparts. 
DISTRIBUTION 
Western Australia, Papua New Guinea. 
DISCUSSION 
Although at first sight Leucosia angulata (RATHBUN, 1911) 
and L. galantua can be confused because of their angular 
antero-lateral margins of the carapace and their quadrilobate 
front, they are clearly separated by the form of the tubercles 
on the anterior margin of the merus of the chelipeds, these 
tubercles being flattened and tooth-like in L. angulata, while 
rounded and pearl-shaped in the new species. The ornamen-
tations of the thoracic sinus are different in both species : 
one large mushroom-shaped tubercle in L. angulata versus 
2-3 large rounded tubercles in L. galantua. Whether the 
presence of a tooth on the intestinal region is a good distinc-
tive character between the two species remains questionable 
as mentioned earlier (OvAERE, 1987) in relation to the varia-
bility of this character in L. sagamiensis SAKAI, 1961. Never-
theless L. galantua sp. nov. is more closely related to L. 
angulata than to any other Leucosia yet described. 
The new species belongs to the group of urn-shaped, fur-
bearing Leucosia as described in Ov AERE, 1987. 
Acknowledgements 
I am most grateful to Dr. G. MoRGAN and Dr. D.S. JoNES 
of the Western Australian Museum for borrowing specimen 
227-60. I wish to thank Dr. J. VAN GoETHEM and Dr. K. 
WouTERS for their encouragement and critically reading of 
the manuscript. The Papua New Guinea research project 
is supported by the Leopold III Foundation and by the 
F.K.F.O. (Belgian Fund for Joint Basic Research). 
I I 
Leucosia galantua sp. nov. from Australia and Papua New Guinea 97 
3 
Figs. 1-3. - Leucosia galantua sp. nov. 
I . female holotype WAM 227-60, dorsal view; 2. f emale holotype WAM 227-60, ventral view with chelipeds in different 
positions to show the thoracic sinus; 3. juvenile fema le para type BC 11 68 , dorsal view. Scale = 1 mm. 
98 A.A. OV AERE 
Literature cited 
OvAERE, A.A., 1987. The fur-bearing species of the genus Leuco-
sia from Northern Papua New Guinea, with a description of two 
new species (crustacea, Brachyura). Bulletin de 1' lnstitut Royal 
des Sciences Naturelles de Belgique, Biologie, 57 : 185-204. 
RATHBUN, M.J., 1911. The Percy Sladen Trust Expedition to the 
Indian Ocean in 1905. No. XI. Marine Brachyura. The Trans-
actions of the Linnean Society of London, Zoology, 14 (2): 191-
261, pl. 15-20. 
SAKAI, T., 1961. New species of Japanese crabs from the Collec-
tion of His Majesty the Emperor of Japan. Crustaceana, 3 (2) : 
131-150. 
'' 
TYNDALE-BiscoE, M. & GEORGE, R.W., 1962. The Oxystomata 
and Gymnopleura (Crustacea, Brachyura) of Western Australia 
with Descriptions of Two New Species from Western Australia 
and one from India. Journal of the Royal Society of Western 
Australia, 45 (3) : 65-96. 
A.A. 0VAERE 
Recent Invertebrates Section 
Koninklijk Belgisch Instituut 
voor Natuurwetenschappen 
Vautierstraat 29 
B-1040 Brussels, 
Belgium. 


A new species of the genus <i>Leucosia</i> from Australia and Papua New Guinea (Crustacea, Brachyura)

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