THE RAFFLES BULLETIN OF ZOOLOGY 2004
THE RAFFLES BULLETIN OF ZOOLOGY 2004 52(1): 239-249© National University of Singapore

GEOSESARMA HEDNON, A NEW SPECIES OF TERRESTRIAL CRAB
(CRUSTACEA: DECAPODA: BRACHYURA: SESARMIDAE)
FROM TAIWAN AND THE PHILIPPINESPeter K. L. Ng
Department of Biological Sciences, National University of Singapore,
Kent Ridge, Singapore 119260, Republic of Singapore
Email: peterng@nus.edu.sg

H.-C. Liu
Institute of Zoology, Academia Sinica, Nankang, Taipei 115, Taiwan, R.O.C.
Email: liuhc@gate.sinica.edu.tw

Christoph D. Schubart
Biologie 1, Universität Regensburg, 93040 Regensburg, Germany
Email: christoph.schubart@biologie.uni-regensburg.de

ABSTRACT. – A new species of Geosesarma, G. hednon, is described from Taiwan and the Philippines. The
new species represents the northernmost record of this genus. Geosesarma hednon is morphologically closest
to G. maculatum (De Man, 1892) and G. ternatenese (Serène, 1968) (both from Indonesia), but can be
distinguished from them by outer margin of the external orbital tooth being subparallel to the rest of thelateral carapace margin, a short flagellum of the third maxilliped, the shape of the male abdomen, and thestructure of the male first pleopods. Geosesarma hednon has small eggs and marine planktonic larval
development, which distinguishes it from many other species of Geosesarma that are known to have abbreviatedor direct development. This supports current doubts about the homogeneity and monophyly of the genus
Geosesarma.
KEY WORDS. – Sesarmidae, new terrestrial crab, Geosesarma, taxonomy.

INTRODUCTION
Of the over 40 species of sesarmid crabs of the genus
Geosesarma De Man, 1892, known from Southeast Asia andneighbouring areas (Ng, 1988), the most northerly record has
been G. vicentense (Rathbun, 1914) from Port San Vicentein Luzon. The genus has not been previously reported from
Taiwan. In the Philippines, there are two other known speciesof Geosesarma, viz. G. rathbunae (Serène, 1968) [Culasi,
Panay Island] and G. protos Ng & Takeda, 1992 [Mindanao].
In this paper, we describe a new species from the central
Philippines and Taiwan.
The terminology follows Ng (1988). The abbreviations G1
and G2 are for the male first and second pleopods respectively.
All measurements, in millimetres, are of the carapace widthand length respectively. Specimens are deposited in the
Taiwan National Museum, Taipei, Taiwan (TMCD); Instituteof Zoology, Academia Sinica (ASIZ), Nankang, Taipei,
Taiwan; Zoological Reference Collection (ZRC) of the
Raffles Museum of Biodiversity Research, National

University of Singapore; The Naturalis (ex-Rijksmuseum van
Natuurlijke Historie), Leiden, The Netherlands (RMNH); andthe Senckenberg Museum (SMF), Frankfurt a. M., Germany.

TAXONOMY
Geosesarma De Man 1892
Remarks. – The genus Geosesarma De Man 1892 (sensu
Serène & Soh, 1970) is clearly not homogeneous, and Ng(1988: 119) recognised three separate groups for convenience.
As has been discussed by some authors (see Ng, 1988: 118),
the genus Geosesarma is not well defined, and is characterised
mainly by their wholly freshwater habits, swollen basal
antennular segment and large eggs (ca. 1.0 mm in diameteror larger). Many other sesarmid genera, however, also haverepresentatives living in fresh water habitats, sometimes great
distances from the sea. The swollen antennular segment is a
useful character, but is not always reliable as it is also evident
in members of other genera (e.g. Labuanium) (unpublished239

Ng et al.: New terrestrial crab of the genus Geosesarmadata). The egg sizes of many species currently referred toGeosesarma are still not known, and it is doubtful if thischaracter alone is sufficient to diagnose a genus. The
development of only two species is known for certain, G.
peraccae and G. notophorum. Geosesarma peraccae has anabbreviated development, with the advanced zoeae possessing
their own food reserves and developing rapidly in the burrows(Soh, 1969), while G. notophorum has direct developmentwith the young crabs staying on the mother’s back for a shorttime (Ng & Tan, 1995). Large eggs and abbreviateddevelopment have also been reported for other inland andcoastal sesarmid taxa (Hartnoll, 1964; Schubart & Cuesta,
1998; Cuesta et al., 1999; Schubart & Ng, in prep.).
The present description of a new species, G. hednon, fromthe central Philippines and Taiwan is noteworthy as the twosites are some distance apart. However, many ovigerous
females of G. hednon had been obtained and the eggs are
small, much smaller than those known for other Geosesarma
species (see Ng 1988: 118). The eggs from some of theseovigerous females hatched into normal planktonic zoeae andthey will be described at a later date. As such, this species
has a rather wide distribution compared to more typical

Geosesarma species. Geosesarma hednon thus lacks one of
the key attributes of the genus, i.e. the possession of large
eggs with abbreviated or direct development. The authors
have on hand, ovigerous females of G. nemesis Ng, 1986, G.
cataracta Ng, 1986, G. tiomanicum Ng, 1986, G. penangense
Tweedie, 1940, G. malayanum Ng & Lim, in Ng, 1986, G.
aurantium Ng, 1995, and G. noduliferum (De Man, 1892),
all of which have large eggs. We expect some of the other
Geosesarma species (e.g. G. maculatum) to also have small
eggs like G. hednon. While we have seriously consideredestablishing a new genus for G. hednon and its close allies(the type species of Geosesarma is G. noduliferum), we havedeferred from doing so as the affinities of too many of thespecies in the genus are still poorly understood. Most of thespecies have not even been reported or redescribed since their
original discovery.

Geosesarma hednon, new species(Figs. 9-14)
Material examined. – Holotype – male (13.4 by 12.3 mm) (TMCD),
mouth of Kangkou stream Manchow, Pingtung County, Taiwan,
21°59'26" N 120°50'09"E, coll. H.-C. Liu, 7 Jan.2000.
Paratypes – Taiwan: 3 males (13.9 by 13.3 mm, 11.4 by 11.0 mm,
11.0 by 10.4 mm) (ZRC), mouth of Kangkou stream, Manchow,
Pingtung County, 21°59'26" N 120°50'09"E, coll. H.-C. Liu, 13
Dec.1999 ;1 female (12.6 by 11.4 mm) (SMF 28101) (DNAvoucher), mouth of Kangkou Stream, Pingtung County, 21°59'26"
N 120°50'09"E, coll. H.-C. Liu, 1 Sep.1999 ;1 male (13.1 by 12.1mm) (TMCD), mouth of Kangkou stream, Manchow, PingtungCounty, 21°59'26" N 120°50'09"E, coll. H.-C. Liu, 17 Dec.1999 ;2Fig. 1. Geosesarma maculatum (De Man, 1892). Male (12.8 by 12.2mm) (RMNH D30584), Sumba. A, overall view; B, carapace; C,
frontal view.

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Fig. 2. Geosesarma maculatum (De Man, 1892). Male (12.8 by 12.2mm) (RMNH D30584), Sumba. A, ventral view; B, right chela, outerview.

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males (10.1 by 9.4 mm, 8.8 by 8.5 mm), 2 females (8.0 by 7.1 mm,
7.0 by 6.4 mm) (TMCD), 2 males (9.9 by 9.4 mm, 6.8 by 6.4 mm),
1 female (10.9 by 9.9 mm) (ZRC), mouth of Meilun stream, Hualien
City, Hualien County, 23°58’54"N 121°36’37"E, coll. H.-C. Liu,
18 Jun.2000 ;2 females (10.3 by 9.6 mm, ovigerous; 8.3 by 7.3 mm)(TMCD), mouth of Meilun stream, Hualien City, Hualien County,
23°58’54"N 121°36’37"E, coll. H.-C. Liu, 12 Jul.2000 ;1 female(12.3 by 11.1 mm, with larvae) (TMCD), mouth of Meilun stream,
Hualien City, Hualien County, 23°58’54"N 121°36’37"E, coll. H.C. Liu, 21 Sep.2000 ;1 female (13.7 by 12.2 mm, with larvae)(TMCD), mouth of Meilun stream, Hualien City, Hualien County,
23°58’54"N 121°36’37"E, coll. H.-C. Liu, 19 Jun.2000 ;1 female(9.5 by 8.5 mm, ovigerous), mouth of Meilun stream, Hualien City,
Hualien County, 23°58’54"N 121°36’37"E, coll. H.-C. Liu, 3
Oct.2000 ;1 male (12.6 by 11.5 mm), 1 female (12.4 by 11.3 mm),
2 juveniles (ZRC 2002.416), mouth of Meilun stream, Hualien City,
Hualien County, 23°58’54"N 121°36’37"E, coll. P. K. L. Ng & H.C. Liu, 22 Jun.2002.
Other material – Philippines: 2 males (17.7 by 16.0 mm, 11.6 by
10.7 mm), 2 females (17.7 by 15.6 mm, 12.7 by 11.1 mm) (ZRC),
1 male (13.7 by 13.0 mm) (TMCD), 1 female (13.2 by 11.7 mm)(ASIZ), Kawasan Falls, Matutinao River, western Cebu, Philippines,
coll. H.-C. Liu, 4 Dec.2001.

Diagnosis. – Carapace squarish, dorsal surfaces finely
granular; external orbital tooth with outer margin almost
straight and flush with rest of lateral margin, separated fromrest of margin by narrow cleft; lateral carapace margins
subparallel; exopod of third maxilliped slender, with shortflagellum (sometimes absent); dactylus of male chela withnumerous unevenly arranged simple sharp granules on dorsal
margin; meri of ambulatory legs relatively broad, ventral
margins of first dactylus and propodus usually with brushlike setae in adults; thoracic sternites 3 and 4 separated bygently curved ridge, with anterior and posterior surfaces
depressed; abdomen triangular; G1 relatively slender, distal
chitinous part very elongate, ca. half length of basal segment,
tip forked.
Description of male. – Carapace squarish, slightly broader
than long, broadest at posterior part of carapace, dorsal
surfaces finely granular, regions not prominently swollen,with distinct grooves separating them; transverse groove
separating cardiac and intestinal regions distinct;
posterolateral regions with well developed oblique striae.
Frontal margin strongly deflexed, slightly sinuous from dorsal
view, vaguely divided into 2 low, subtruncate lobes;
postfrontal cristae distinct, sharp, almost straight, separated
into 4 parts, median parts separated by deep fissure, lateralparts separated by short, narrow fissure; frontal region
concave. Antero- and posterolateral margins not discernible;
external orbital tooth low, directed anteriorly, outer marginusually almost straight and flush with rest of lateral margin,separated by small, relatively narrow cleft; lateral carapace
margins gently convex to almost straight, subparallel, no otherlateral teeth discernible. Merus of third maxilliped
longitudinally ovate, widest part much wider than length ofproximal margin; ischium with shallow median sulcus;
exopod slender, with short, slender flagellum that does notextend across width of merus, sometimes vestigial or absent.
Male chelipeds subequal; outer surface with numerous
rounded granules singly or in small clumps. Merus withnumerous rounded granules on outer surface; outer and inner
margins serrated, without subdistal spines; inner margin with
distal part dilated, sublamelliform. Carpus with outer surface
granulated; longer than broad; inner distal angle with several
sharper tubercles but without distinct tooth or spine. Palm
inflated, especially on inner surface; dorsal and inner surfaces
with numerous rounded granules; outer surface of larger maleswith median part almost smooth to pitted; fingers slightly
longer than palm, forming small gape proximally whenclosed; dactylus with numerous unevenly arranged simple
sharp granules on dorsal margin, cutting margin with several
teeth and denticles; pollex with several low teeth, may beeroded in larger specimens.

Fig. 3. Geosesarma maculatum (De Man, 1892). Male (12.8 by 12.2mm) (RMNH D30584), Sumba. Ambulatory legs. A, ventral viewof first propodus and dactylus; B, dorsal view of second (top) andthird (below) propodi and dactyli; C, dorsal view of fourth propodus
and dactylus.

Second and third ambulatory legs longest, meri of all legs
relatively broad (cf. Ng, 1988). Upper margin weakly but
unevenly serrated, with a low, but not spiniform subdistal
tooth; dorsal and ventral margins of merus and carpus with
scattered long setae. Dorsal and ventral margins of propodus
and dactylus with numerous long, stiff setae, but not obscuringmargins. Ventral margins of first dactylus and propodus with241

Ng et al.: New terrestrial crab of the genus Geosesarma
densely packed short setae forming brush-like structures insmaller specimens, absent or sparser in larger specimens;
brush-like setae usually present on second dactylus andpropodus but sparser; absent on dactylus and propodus of
third and fourth legs.
Thoracic sternites with smooth surface; sternites 3 and 4
separated by gently curved ridge, surfaces anterior andposterior to this ridge depressed; abdominal cavity reachingslightly beyond midpoint of sternite 4. Abdomen triangular.
Telson with lateral margins convex, slightly longer thanbroad, tip rounded. Segment 6 with lateral margins convex,
much broader than long. Segments 3-5 increasingly
trapezoidal; lateral margins of segments 4 and 5 gently
concave, that of segment 3 gently convex. Segments 1 and
2 transversely very narrow.
G1 relatively slender; basal segment gently sinuous; distal
chitinous part very elongate, ca. half length of basal segment,
gently sinuous from dorsal view and subspatuliform frommarginal view; tip gently forked. G2 short, without distalsegment.
Variation. – The female specimens agree with the male inalmost all non-sexual characters, although in a few females,
the carapace regions are slightly more inflated. The relative

length of the male telson compared to segment 6 varies
somewhat. In smaller males, the telson is usually slightly
longer or subequal to the length of segment 6 (Fig. 13A),
becoming relatively shorter in larger specimens (Fig. 14A).
Similarly, the lateral margins of male abdominal segment 6
are more prominently convex in larger specimens.
Geosesarma hednon is sexually dimorphic in the size of thechelae (larger chelae with higher palms in males) and in thebrush-like pubescence at the ventral side of the first two
ambulatory legs, which is absent in females, suggesting a
possible role during mating.
Colour. – Dorsal surface mostly brown to yellowish-brown,
sometimes with dark-purple streaks which are bilaterally
positioned; frontal region distinctly dark purple to almost
black, stopping sharply at postfrontal cristae; posterolateralsurface and margin with prominent broad dark purple to blackband which is sharply demarcated, even in juveniles. Dorsal
surfaces of ambulatory legs light brown, ventral surfaces ofmerus yellowish to dirty white. Ocular peduncle brightyellowish-green on dorsal surface, lateral and ventral surfaces
purplish; cornea black with numerous small iridescent green
spots. Third maxillipeds purple; oblique median ridge ofmerus and adjacent areas yellowish-green to yellow. Merus
and carpus of chelipeds purplish, with yellowish patches.
Outer surface of chela mostly light purple to purple, with

Fig. 4. Geosesarma maculatum (De Man, 1892). Male (12.8 by 12.2 mm) (RMNH D30584), Sumba. A-D, left G1 (setae denuded). Scales:
A, B = 1.0 mm, C, D = 0.5 mm.

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median parts sometimes somewhat yellowish; fingers dull
red with dorsal surface of dactylus purplish, distal one-quarteror one-fifth yellowish orange to yellow, tips corneous.
Thoracic sternum dirty to brownish-white.
Etymology. – The name is derived from the Greek “hednon”
for wedding gift. This alludes to the circumstances during
which the species was discovered. The species was first
identified as a new Geosesarma species by the third author
from among the second author’s material during the second
author’s engagement. The species name represents a gift by
the second author to his wife; and a wedding gift to the couple
from the first and third authors. The name is used here as anoun in apposition.
Remarks. – Geosesarma hednon, new species, is closest to
G. maculatum (De Man, 1892) and G. ternatense (Serène,1968). The identity of G. maculatum s. str. is not very clear.

The species was described from Flores (Lesser Sunda Islands)(as a Sesarma, De Man, 1892: 347, Pl. 21 Fig. 19), and was
subsequently reported from Ternate, Batjan and Halmahera
in eastern Indonesia by De Man (1902: 517). Gordon (1937)
examined the Ternate specimen and argued that it was notconspecific with real G. maculata but she did not apply a
new name. Serène (1968: 1092) stated that G. maculatum s.
str. could be distinguished by the presence of brush-like setaeon the first and second ambulatory propodus and dactylus;by the telson being as broad as long, with segment 6 being
proportionately less broad, the male abdominal cavity notreaching as far forwards to the ridge between thoracic sternites
2 and 3, and the tip of the G1 being somewhat flared anddistinctly bilobed (Figs. 1-4, 8A) (see also Gordon, 1937:
150, Figs. 1, 2c, d, 3a-c). On this basis, he argued that the
specimens of G. maculatum reported from Ternate (see also
Gordon, 1937) should be referred to a new species, G.
ternatense (Serène, 1968) (see present Figs. 5-7, 8B). The
identity of the Batjan and Halmahera specimens will need tobe verified (see Cai & Ng, 2000). We have examined
specimens of G. maculatum and G. ternatense, including theholotype of the latter species (see also Fransen et al., 1997:
123) and we concur with Serène’s (1968) observations andconclusions.
From both G. maculatum and G. ternatense, G. hednon canbe distinguished by the outer margin of the external orbital

Fig. 5. Geosesarma ternatense (Serène, 1968). Holotype male (13.9
by 12.9 mm) (RMNH D1205a), Ternate. A, overall view; B, frontal
view; C, ventral view.

Fig. 6. Geosesarma ternatense (Serène, 1968). Holotype male (13.9
by 12.9 mm) (RMNH D1205a), Ternate. Ambulatory legs. A, leftsecond or third leg; B, right fourth leg; C, right first or second leg.

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Ng et al.: New terrestrial crab of the genus Geosesarma

Fig. 7. Geosesarma ternatense (Serène, 1968). Holotype male (13.9 by 12.9 mm) (RMNH D1205a), Ternate. A, right side of carapace(schematic); B-E, left G1 (setae denuded). Scales: A = 2.0 mm, B, C = 1.0 mm, D, E = 0.5 mm.

Fig. 8. Male abdomen (segments 3-6 and telson). A, Geosesarma maculatum (De Man, 1892), male (12.8 by 12.2 mm) (RMNH D30584),
Sumba; B, G. ternatense (Serène, 1968), holotype male (13.9 by 12.9 mm) (RMNH D1205a), Ternate. Scales = 2.0 mm.

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tooth being subparallel to the rest of the lateral carapace, andseparated from it by a small or narrow cleft (Figs. 9B, 11B)
(vs. outer margin sharply sloping inwards towards thecarapace centre and the cleft with the lateral carapace margin
distinctly V-shaped, Figs. 1B, 5A, 7A); the flagellum of the
exopod of the third maxilliped being not longer than the widthof the merus (sometimes vestigial) (vs. flagellum long, longer
than width of merus); the elongate distal chitinous part of the
G1 being proportionately longer (Figs. 13C-G, 14C-H vs.
Figs. 4A-D, 7B-E) and the basal part being more sinuous(Figs. 13C-G, 14C-H vs. Figs. 4A-D, 7B-E). Geosesarma
hednon can be distinguished from G. ternatense in possessing
brush-like setae on the first and second ambulatory propodi
and dactyli (completely absent in G. ternatense). The maleabdomen of G. ternatense is remarkably broad and very
diagnostic (Fig. 8B) and easily distinguishes this species fromthe other two. The male abdomen of G. hednon (Figs. 13A,
14A) is also relatively more transversely narrow than that of
G. maculatum (Fig. 8A).
The taxonomic value of the presence or absence of brushlike setae on the ventral margins of the first and second
ambulatory propodus and dactylus depends to some degree

Fig. 9. Geosesarma hednon, new species. Holotype male (13.4 by
12.3 mm) (TMCD), Taiwan. A, overall view; B, carapace; C, frontalview.

on the size of the specimen. It has been used as a taxonomic
character to separate various sesarmid species (e.g. byGordon, 1937; Serène, 1968; for Geosesarma species) but isknown to be variable to some degree and is always absent infemales (see Ng, 2002). In the present series of G. hednon
from Taiwan, this character varies somewhat. In males, thebrush-like setae on the first and second ambulatory dactylus
are short but distinct; on the propodus, they are arranged insmall tufts and are neither as dense or fully continuous (Figs.
10B, 13I). In a large male of G. hednon from the Philippines(17.7 by 16.0 mm, ZRC), the brush-like setae of the firstambulatory dactylus are markedly more ragged and sparser
compared to the smaller males, and in this specimen, they
are also not discernible on the first ambulatory propodus aswell as second ambulatory propodus and dactylus. Malespecimens of G. hednon from Taiwan and Philippines smaller
than the holotype invariably have more prominent brush-likesetae. In the male specimen of G. maculatum examined, thesebrush-like setae are very dense and distinctly longer (Figs.
3A, B) compared to those of G. hednon (Figs. 10B, 13I).
Three other Geosesarma species have G1 structures which
are similar to the three species discussed above, viz. G.
sylvicolum (De Man, 1892), G. gordonae (Serène, 1968) and

Fig. 10. Geosesarma hednon, new species. Holotype male (13.4 by
12.3 mm) (TMCD), Taiwan. A, ventral view; B, left first ambulatory
propodus and dactylus; C, left second ambulatory propodus anddactylus.

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Ng et al.: New terrestrial crab of the genus Geosesarma
G. johnsoni (Serène, 1968) (see Gordon, 1937; Serène, 1968),
and all are probably related. Compared to G. hednon, theircarapace and G1 structures are different. When a full revisionof the genus is eventually done, hopefully supported bymolecular data, these species, together with G. maculatum,
G. ternatense and G. hednon, will probably have to be referredto their own genus.
Ecological notes. – Geosesarma hednon occurs on the sideof river banks, under forest cover or in burrows. It has beencollected from burrows that it apparently digs itself, as well
as from under stones or in crevices. In Taiwan, G. hednon
occurs sympatrically with Sesarmops intermedium, S.
impressum, Chiromantes haematocheir and Neosarmatium
rotundifrons (all Sesarmidae); and in the Philippines, it has
been collected with Sesarmops weberi and Bresedium
philippinense (both Sesarmidae). The preferred habitats areusually close to fresh water pools or streams (often within a
10 m radius). In Taiwan, the species was collected less than
300 m away from the sea, but in the Philippines, it was
obtained slightly further away (ca. 500 m). This species has

secretive habits and does not wander far from cover. The only
exceptions are ovigerous females which need to migrate to
the sea to release their larvae. Of the 38 ovigerous females
from Taiwan that were examined (not all preserved), thesmallest specimen measured 9.5 mm in carapace width.
Ovigerous females were found all year round. Ovigerous
females have small eggs that hatch out into pelagic, freeswimming larvae. The release of larvae does not appear to
be associated with lunar or semilunar cycles, with many
ovigerous females also observed during other periods.
Comparative material. – G. maculatum (De Man, 1892): 1 male
(12.8 by 12.2 mm), 1 female (11.0 by 10.3 mm) (RMNH D30584),
Bondokodi River, 2-3 km from river, west Sumba, Indonesia, coll.
E. Sutter, 10 Aug.1949; 1 female (RMNH D38588), Roti, Timor,
Indonesia, coll. H. Ten Kate, 1891. G. ternatense (Serène, 1968):
Holotype male (13.9 by 12.9 mm) (RMNH D1205a), Ternate, coll.
Kükenthal Expedition; 1 female (14.0 by 12.8 mm) (RMNH
D1205b), same data as holotype.

ACKNOWLEDGEMENTS
The study has been partially supported by a research grantto the first author from the National University of Singapore;
and a research fellowship, including travel funds to Taiwan,

Fig. 11. Geosesarma hednon, new species. Male (17.7 by 16.0 mm)(ZRC), Philippines. A, overall view; B, carapace; C, frontal view.

246

Fig. 12. Geosesarma hednon, new species. Chelae. A, B, holotype
male (13.4 by 12.3 mm) (TMCD), Taiwan; C, male (17.7 by 16.0mm) (ZRC), Philippines.

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Fig. 13. Geosesarma hednon, new species. Holotype male (13.4 by 12.3 mm) (TMCD), Taiwan. A, abdomen; B, right fourth ambulatoryleg; C-G, left G1 (setae denuded); H, left G2 (setae denuded); I, right first ambulatory propodus and dactylus. Scales: A, B = 2.0 mm, CE, H = 1.0 mm, E, G = 0.5 mm.

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Ng et al.: New terrestrial crab of the genus Geosesarma

Fig. 14. Geosesarma hednon, new species. A, D-H, male (17.7 by 16.0 mm) (ZRC), Philippines; B, C, male (11.6 by 10.7 mm) (ZRC),
Philippines. A, abdomen; B, right fourth ambulatory leg; C-H, left G1s (setae denuded). Scales: A = 5.0 mm, B = 2.0 mm, C-F = 1.0 mm,
G, H = 0.5 mm.

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to the third author from the Raffles Museum, National
University of Singapore. Lawrence Liao (University of San
Carlos, Cebu City, Philippines) kindly helped us withcollections in the Philippines. Charles Fransen (RMNH)
kindly sent us the material of G. maculatum and G. ternatense.

Ng, P. K. L., 1988. The Freshwater Crabs of Peninsular Malaysia
and Singapore. Department of Zoology, National University ofSingapore, Shinglee Press, Singapore, pp. i-viii, 1-156, 4 colour
pls.

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