THE RAFFLES BULLETIN OF ZOOLOGY 2002 50(2): 419-435@ National University of Singapore

NEW SPECIES OF CAVERNICOLOUS CRABSOF THE GENUS SESARMOIDES FROM THE WESTERN PACIFIC,WITH A KEY TO THE GENUS(CRUSTACEA:DECAPODA:BRACHYURA:SESARMIDAE)Peter K. L. Ng
Department ofBiological Sciences,National University of Singapore,
Kent Ridge, Singapore 119260,Republic of Singapore
Email: petemg@nus.edu.sgj'ABSTRACT. -Five newspeciesof cavemicoloussesarmidcrabs of the genusSesartnoidesare describedfrom Indonesia,Loyalty Islands,Philippinesand Guam,viz., S. balicus,S. loyalty,S. sulu,S. boholanoandS. guamensis.Diagnosesand detailedfigures are provided for all species.The taxonomyof S. emdi Ng &Whitten, 1995,is also clarified, and a key to the 14 recognisedspeciesof Sesartnoidesis provided.

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KEY WORDS. -Taxonomy, Sesarmidae,Grapsidae,Indonesia, Loyalty Islands, Philippines, Guam,anchialine caves, new species,Sesartnoides.

I

ii

INTRODUCTIONFAMILYOver the last few years, the author has obtained numerous
specimens of cavernicolous sesarmid crabs from various
parts of the western Pacific, including Southeast Asia. Mostof them belonged to the genus Sesarmoides Serene & Soh,
1970, and all appear to be undescribed. The present paper
reports on the five new species from Indonesia, Philippines,
Guam and Loyalty Islands. A key to the 14 recognised
species is also provided.

GRAPSillAE

MACLEAY,

1838

Genus Sesarmoides Serene & Soh, 1970

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Type species. -Sesarma kraussi De Man, 1887, by original
designation.
...
Re".'~rks.. -In ~eIr reVISIon of the ge~era ofthe!ndo-West
PacIfIc Sesarmmae. (present SesarmIdae), Seren~ & Soh(1970: 403) establIshed a new genus, Sesarmozdes, for
species with a relatively flattened carapace with strongly
divergent lateral margins, a narrow frontal margin which isshorter than the postenor carapace margIns, a.
and globular basal antennal segment wIth a nearlylongItudinal peduncle, an epistome WIth a distInct transverse
rim and deepmedian notch, and slender and long ambulatory
legs, with the third leg (pereiopod 4) more than twice thenat.Iona~ ,d HIS!OIre .n~tu~elle (MNHN), Pan~, Fra~~e;UmversIta deglI StUdi dl Firenze, Museo ZOOIOgiCOde La
Specola", Firenze (MZF), Italy; Florida Museum of Natural
History (FMNH) , Gainesville, Florida, U.S.A.; and the
Zoological Reference Collection (ZRC) of the Raffles
Museum of Biodiversity Research, National University ofSingapore. Measurements, inmillimetres, are of the carapace
widthandlengthrespectively.TheabbreviationsGlandG2
are used for the male first and second pleopods respectively.
The first to fourth ambulatory legs correspond to the second
to fifth pereiopods respectively. The terminology used here
essentially follows Ng (1988).

length of the carapace. The genus currently contains nine
Indo-West Pacific species, viz. S. borneensis (Tweedie,
1950), S. cerberus (Holthuis, 1964), S. emdi Ng & Whitten,
1995,S.jacksoni(Balss, 1934),S.jacobsoni(Ihle, 1912),S.
kraussi (De Man, 1887) (type species by original
designation), S. longipes (Krauss, 1843), S. novabritannia
Ng, 1988, and S. ultrapes Ng, Guinot & niffe, 1994 (seeSerene & Soh, 1970; Ng, 1988a; Ng et al., 1994; Ng &Whitten, 1995). Two Atlantic species that Serene & Soh(1970) suggested may also be Sesarmoidesspecies, Sesarma
verleyi Rathbun, 1914, and Sesarmajarvisi Rathbun, 1914,
are not included here as they differ from typical Sesarmoides

419

Ng: On the genus Sesarmoides
in severalmajoraspectsincluding atthe molecularlevel (seealso Abele, 1992; Schubartet al., 1998). They are retainedin SesarmaSay, 1817, sensustricto.

Sesarmoidesemdi Ng & Whitten, 1995
(Figs. 2, 3, 9A, B, lOA)
Sesarmoidesemdi Ng & Whitten, 1995: 370 (part), Figs. 1-6.

Ng et al. (1994) and Ng & Whitten (1995) commented that
there are two species groups in Sesarmoides. One group
includes three species usually associated with mangroves,estuarine areasand sometimes coastal caves,viz. S. longipes,
S. kraussi and S. borneensis, and morphologically, aredistinguished by their smaller adult carapace size, a relatively
shallower groove between the epigastric regions (Figs. lA,B), presence of a longitudinal row of small granules or ridgeon the outer surface of the pollex (Fig. 1 C), and the G 1
relatively more slender. The second group contains usuallyrelatively larger species, with swollen epigastric regions
separated by a deeeper groove, often possessing a row of
granules on the dorsal margin of the dactylus of the chelipeds,
and there are no longitudinal row of granules or ridge on theouter surface of the pollex, and include S. jacobsoni, S.
cerberus, S. novabritannia, S. ultrapes, S. emdi and possibly
S. jacksoni.

Fig. 1. Sesarmoidesborneensis.Male (12.3 by 9.7 mm) (ZRC),
Kampung Ladong, Pu1auTekong,Singapore.A, overall view; B,
carapace;C, chela.

420

Material examined.-Holotype -male (17.8 by 15.5 mm) (MZB),
100 m from opening of Gua Paoncave, Dusun Karangsan,Desa
Suana,Nusa Penida, southeastof Bali, Indonesia, coli. A. J.
Whitten, 12 Dec.1993.
Paratypes-2 males(23.7by 20.5mm, 18.5by 15.5mm), 1 female(14.6 by 11.8 mm) (ZRC 1995.278),Gua Girl Putrl cave, 50 m
asl,DusunKarangsari,DesaSuana,NusaPenida,southeast
of Bali,Indonesia,colI. A. J. Whitten, 21 Mar.1994.
Diagnosis (holotype). -Carapace approximately trapezoidal
in shape; anterior regions well defined, almost glabrous;
lateral regions covered with oblique striae; epigastric region
pronounced, separated by prominent groove; frontal margin
with prominently concave median emargination; external
orbital tooth with tip not extending beyond level of frontal
margin; outer margin almost straight to gently convex,
separated from first anterolateral tooth by small V -shaped
cleft; first anterolateral tooth separated from second
anterolateral tooth by fissure. Chelae relatively stout, fingers
subequal to length of palm; ventral margin of pollex gently
concave. Ambulatory legs very long, in males, length towidth ratios of meri of second and third legs 4.3 and 4.0
respectively; dorsal and ventral margins with weak serrations,more prominent distoventrally, dorsal subdistal edge angular
but not spiniform; brush-like setaepresent on ventral margins
of propodi and dactyli of first and second legs, setae usuallysparse on propodi and dactyli of third leg and completely
absent on fourth leg. Prominent tufts of short setae between

Fig. 2. Sesarmoidesemdi. A, paratypemale (18.5 by 15.5 mm)(ZRC 1995.278),Bali; B, paratypefemale(14.6by 11.8 mm)(ZRC
1995.278),Bali.

THE RAFFLES BULLETIN OF ZOOLOGY 2002

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Fig. 3. Sesarmoidesemdi. Paratypemale (18.5 by 15.5 mm) (ZRC 1995.278),Bali. A, carapace;B, second ambulatoryleg; C, thirdambulatoryleg; D, abdominalsegments4-6 and telson; E, left Gl; F, G, distal part of left Gl (denuded)(after Ng & Whitten, 1995:Fig.
6C, D). Granulesand setaeon structuresomitted. Scales:A-C = 5.0 mm, D = 2.0 mm.

421

Ng: On the genusSesarmoides
coxae of first to third ambulatory legs. Male abdomen lessbroad, lateral margins of male telson subparallel. G I
relatively short, stout, inner margin almost straight; distal
part sharply bent outwards and slightly downwards, chitinous
distal part short.
Paratypes. -Only one female specimen is known, andalthough rather small, is almost adult size. The only
significant non-sexual difference with the other types seemto be the presence of very short and widely but evenly spaced
setae on the dorsal surface of the carapace, especially on theanterior part; and none of the ambulatory leg segments
possess brush-like setae.

Colour. -The dorsal surface of the carapace is dark
purplish-brown,ambulatorylegs dark brown, carpusof thecheliped purplish with the chelaebright orange(seeNg &Whitten, 1995).
Remarks. -Recently, as part of the comparisons with smaller
allied species from Philippines (S. boholano, new species)
and Guam (S. guamensis, new species), the author reexamined all the type specimens of S. emdi. One of thesmaller paratype male specimens (17.8 by 15.4 mm)
appeared slightly different from the other males in having
a more setose carapace, different anterolateral margin
armature, proportionately shorter ambulatory legs and atel son that had the lateral margins relatively more subparallel.
In describing S. emdi, Ng and Whitten (1995: 371), had notedthat one of "... the smaller paratypes (17.8 x 15.4 mm) hasvery small tufts of setae scattered on its carapace ..." butthey accepted this as part of the variation within the species.

to S. emdi. The other male paratypes agree with the holotype
male of S. emdi in all the original diagnostic characters,
including the structure of the G I; while the sole female
paratype has the same type of anterolateral armature as theholotype of S. emdi. While the dorsal surface of the carapaceof the paratype female is more setose (Figs. 2B, 9B) (likethat of S. balicus), such variation between sexes is known
for some Sesarmoides species (e.g. S. guamensis) and is notconsidered to be significant.
The presence of two closely related-species in the same cavein Bali is very surprising, but the differences observed here
warrant suchan action. More collections will need to be madeto ascertain if the niches of S. emdi and S. balicus reallyoverlap.

Sesarmoidesbalicus, new species(Figs. 4A, 5, 9C, lOB)
Sesarmoidesemdi Ng & Whitten, 1995: 370 (part).
Material examined.-Holotype -male (17.8by 15.4 mm) (ZRC),
Gua Giri Putri Cave,50 m asl, Dusun Karangsarl,Desa Suana,
Nusa Penida,southeastof Bali, Indonesia,coIl. A. J. Whitten, 21
Mar. 1994.

Diagnosis(holotype).-Carapace approximatelytrapezoidal
in shape;anteriorregions well defined, with short, widely
but evenlyspacedsetae;lateralregionscoveredwith obliquestriae;epigastricregionpronounced,separatedby prominent
groove;frontal margin with concavemedianemargination;
externalorbital tooth with tip not extendingbeyondlevel ofA re-examination of this specimen's (17.8 by 15.4 mm) G1and
removal of the dense setae surrounding the chitinousdistal
part showed that it actually differs markedly from theG1 s of the other type specimens of S. emdi, with its chitinousdistal
part far longer than can be accounted for by growthor variation. The G 1 difference is so substantial (Figs. 5E-G
vs. Figs. 3E-G) that there can be question that two speciesare
involved. As such, the differences observed in thecarapaceof the 17.8 by 15.4 mm specimen (more setoseanterior part of the dorsal surface [Figs. 4A, 9C], vs. glabrous[Figs. 2A, 9A]); anterolateral margin (the external orbital
and anterolateral teeth separatedby very shallow clefts [Figs.
5A, 9C], vs. deep [Figs. 3A, 9A]); male telson form (lateralmargins
gently diverging backwards [Fig. 5D], vs.
subparallel [Fig. 3D]), as well as the shorter leg proportions(length to width ratios of meri of second and third ambulatory
legs 3.3 and 3.6 respectively, vs. 4.1 and 4.5 respectively[Figs. 5B, C vs. Figs. 3B, C]), cannot be considered to be
mere variation within S. emdi. While many species ofcavernicolous Sesarmoides species previously describedhave beenbased on only a few specimens,the excellent seriesof S. boholano and S. guamensis studied here show that thedifferences discussed above cannot be attributed to just infraspecific variation.
As such, a new species,S. balicus, has been established forthe 17.8 by 15.4 mm paratype specimen previously attributed422

Fig. 4. A, Sesannoidesbalicus, new species,holotype male (17.8
by 15.4 mm) (ZRC), Bali; S. loyalty, new species,holotype male
(16.3 by 13.7 mm) (MNHN), Loyalty Island.

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Fig. 5. Sesarmoidesbalicus, newspecies.Holotype male (17.8 by 15.4 mm) (ZRC), Bali. A, carapace;B, secondambulatoryleg; C, thirdambulatoryleg; D, abdominalsegments4-6 and telson; E-G, left G1 (denuded).Granulesand setaeon structuresomitted. Scales:A-C= 5.0 mm, D = 2.0 mm, E = 1.0 mm, F, G = 0.5 mm.

423

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Fig. 6. Sesarmoidesloyalty, newspecies.Holotype male (16.3 by 13.7 mm) (MNHN). A, carapace;B, secondambulatoryleg; C, thirdambulatoryleg; D, abdominalsegments4-6 and telson; E-G, left Gl (denuded).Granulesand setaeon structuresomitted. Scales:A-C= 5.0 mm, D = 2.0 mm, E = 1.0 mm, F, G = 0.5 mm.

424

THE RAFFLES.BULLETIN OF ZOOLOGY 2002
frontal margin; outermarginalmostgentlyconvex,separated
from first anterolateraltooth by very shallow notch; firstanterolateraltooth separatedfrom secondanterolateraltoothby small notch. Chelaerelatively stout,fingers subequalto
length of palm; ventral margin of pollex almost straight.
Ambulatory legs long, length to width ratios of meri of
secondand third legs 3.3 and 3.6 respectively; dorsal andventral margins with weak serrations,dorsal subdistaledge
angularbut not spiniform; brush-likesetaepresentonventral
margins of propodi and dactyli of first and second legs,
undiscemible on third and fourth legs. Prominenttufts ofshort setaebetweencoxaeof first to third ambulatorylegs.
Male abdomen relatively broad, lateral margins of maletelsongentlydivergingbackwards.G1 relatively short,stout,
inner margin almost straight; distal part sharply bent
outwardsat approximatelyright angles,chitinous distalpartelongate,straight.
Etymology. -The speciesname is derived from the type
locality, Bali. .
Colour. -Not known, presumablysimilar to S. emdi

Colour. -In the freshly preserved specimen,the dorsal
surface of the carapaceis purplish-brown, with the legsslightly lighter in colour. The chelaeare light orange.
Remarks. -The G 1 of S. loyalty most closely resembles thatof S. balicus, but it is proportionately shorter and stouter(Fig. 6E vs. Fig. SE), the inner submedian margin possessing
a distinct hump (Fig. 6E vs. Fig. SE). Externally, the external
orbital and anterolateral teeth of S. loyalty are also separated
by distinct clefts (Figs. 6A, 9D) (vs. shallow, Figs. SA, 9C),
and the lateral margins of the male telson are subparallel(Fig. 6D) (vs. gently diverging, Fig. SD).

Sesarmoidessulu, new species(Figs. 7, 8, 9E, F, 16A)
Material examined.-Holotype-male (18.9 by 15.1 rom)(MZF),
lateral branch,St. Paul N. P. Cave, PalawanIsland, Philippines,
colI. Borri & C. Volpi, 25 Feb.1991.
Paratype-1 female(23.0 by 18.1 mm) (MZF), betweenentrance
and rocky parts,St. PaulN. P. Cave,PalawanIsland, Philippines,
colI. R. Berti & G. Ferret,23 Feb.1991.

Remarks. -See discussionfor S. emdi

Sesarmoidesloyalty, new species(Figs. 4B, 6, 9D, laC)
Material examined. -Holotype -male (16.3 by 13.7 mm)(MNHN), station NCOO-I14,Peng Cave, Hapetra,Lifou Island,coIl. L. Deharveng & A. Bedos, 26 Oct.2000.
Diagnosis (holotype). -Carapace approximately trapezoidal
in shape; anterior regions well defined, with very shortwidely, evenly spacedsetae; lateral regions covered with low
oblique striae; epigastric region pronounced, separated byprominent groove; frontal margin with gently concave
median emargination; external orbital tooth with tip notextending beyond level of frontal margin; outer margin
almost straight, separated from first anterolateral tooth bu
small V -shaped cleft; first anterolateral tooth separatedfrom
second anterolateral tooth by small fissure. Chelae relatively
stout, fingers subequal to length of palm; ventral margin ofpollex gently concave. Ambulatory legs long, length to width
ratios of meri of second and third legs 3.1 and 3.5
respectively; dorsal and ventral margins with weak serrations,dorsal subdistal edge angular but not spiniform; brush-likesetae present on ventral margins of propodi and dactyli offirst and second legs, undiscemible on third and fourth legs.
Prominent tufts of short setae between coxae of first to thirdambulatory legs. Male abdomen relatively broad, lateral
margins of male telson subparallel. G1 relatively short, stout,with submedian hump along inner margin; distal part sharply
bent outwards at approximately right angles, chitinous distal
part elongate, almost straight.

Etymology. -The speciesis named after its type locality,
Loyalty Islands.The nameis usedas a noun in apposition.

Diagnosis (holotype). -Carapace approximately trapezoidal
in shape; anterior regions well defined, with widely but
evenly spaced short setae; lateral regions covered withoblique striae; epigastric region pronounced, separated byprominent groove; frontal margin with distinct concave
median emargination; external orbital tooth with tip almost
reaching level of frontal margin; outer margin gently convex,
separated from first anterolateral tooth by deep V -shaped
cleft; first anterolateral tooth separated from second
anterolateral tooth by small cleft. Chelae relatively stout,
fingers subequal to length of palm; ventral margin of pollex

Fig. 7. Sesarmoidessuiu, newspecies.A, holotype male (18.9 by
15.1 mm) (MZF), PalawanIsland; B, paratypefemale (23.0 by
18.1 mm) (MZF), PalawanIsland.

425

Ng: On the genus Sesarmoides

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Fig, 8. Sesarmoidessulu, newspecies.Holotypemale (18.9by 15,1 mm) (MZF), A, carapace;B, secondambulatoryleg; C, third ambulatoryleg; D, abdominalsegments4-6 and telson; E-G, left Gl (denuded).Granulesand setaeon structuresomitted. Scales:A-C = 5.0 mm,
D = 2.0 mm, E = 1.0 mm, F, G = 0.5 mm.

426

THE RAFFLES BUUETIN OF ZOOLOGY 2002

Fig. 9. Carapacesof Sesarmoides.A, S. emdi,paratypemale (18.5 by 15.5 mm) (ZRC 1995.278),Bali; B, S. emdi,paratypefemale (14.6
by 11.8 mm) (ZRC 1995.278)Bali; C,S. balicus, new species,holotype male (17.8 by 15.4 mm) (ZRC), Bali; D, S. loyalty, new species,
holotype male (16.3 by 13.7 mm) (MNHN), Loyalty Island; E, S. sulu, new species,holotype male (18.9 by 15.1 mm) (MZF), Palawan
Island; F, S. sulu, new species,paratypefemale (23.0 by 18.1 mm) (MZF), PalawanIsland.

427

Ng: On the genusSesarmoides
gently concave. Ambulatory legs very long, length to width
ratios of meri of second and third legs 3.8 and 4.1
respectively; dorsal and ventral margins with very weak
serrations to almost smooth, dorsal subdistal edge with small
but distinct spine; brush-like setae present on ventral margins
of propodi and dactyli of fITstand second legs, undiscernible
on third and fourth. Prominent tufts of short setae between
coxae of first and second ambulatory legs, not discernible
on third leg. Male abdomen relatively broad, lateral margins
of male telson gently diverging backwards. G 1 relatively
stout, inner margin with very gentle submedian hump; distal
part sharply bent outwards at approximately right angles,
chitinous distal part short, subtruncate.

Paratype.-Only oneparatypefemaleis known. In addition
to the sexual characters, the adult female has a
proportionately broader carapace and relatively longer
ambulatorylegs, especiallythe secondand third legs. The
clefts separatingthe lateralcarapaceteetharealso relatively
deeper, and the setae on the dorso-anterior part of thecarapaceare also shorter.None of the legs havebrush-likesetaeon any of the segments.

Etymology.-The speciesis namedafterthe Sulu Sea,where
PalawanIsland is located.The name is used as a noun inapposition.
Colour. -Not

known. Preserved specimens decolorised.

Remarks. -In the form of the G 1,S. sulu is perhaps closest
to S. emdi, but its inner margin has a gentle submedian hump
(Fig. 8E) (vs. absent, Fig. 3E) and the chitinous distal partis relatively stouter and more truncate (Figs. 8E-G vs. Figs.
3F, G). The second ambulatory leg of S. sulu is also relatively
shorter (length to width ratio of merus 3.8 vs. 4.3) (Fig. 8B
vs. Fig. 3B), and the sixth male abdominal segment is
proportonately less wide (Fig. 8D vs. Fig. 3D).
Two specimens of S. borneensis (1 male, MZF, lateralbranch, St. Paul N. P. Cave, Palawan Island, Philippines,
colI. Born & C. Volpi, 25 Feb.1991; I female, MZF, Palawan
Island, Philippines, coIl. G. Messana, 25 Jan.1991) were alsocollected from Palawan, one with the holotype male of S.
sulu. Sesarmoides borneensis is a new record for thePhilippines.

Sesarmoidesboholano, new species(Figs. 11, 12, 15A, B, 16B, 17b)
Material examined.-Holotype -male (15.6 by 13.1 mm) (USC),
Tawala Cave,Tawala,PanglaoIsland,Bohol, Philippines,colI. P.
K. L. Ng et al., 27 Nov.2001.
Paratypes-1 male (15.1 by 12.3 mm), 1 female (17.5 by 14.3mm) (ZRC), samedataasholotype;4 males(9.9-16.0 by 8.1-13.6mm), 1 female (13.4 by 11.0 mm) (ZRC), Tawala Cave, Tawala,
Panglao,PanglaoIsland, Bohol, Philippines,coli. P. K. L. Ng etFig. 10. Male chelae of Sesarmoides.A, S. emdi,paratype (18.5
by 15.5 mrn) (ZRC), Bali; B, S. balicus, new species,holotype(17.8 by 15.4mrn) (ZRC),Bali; C,S. loyalty, newspecies,holotype(16.3 by 13.7 mm) (MNHN), Loyalty Islands.

428

Fig. 11. Sesarmoides boholano, new species. A, paratype male
(15.1 by 12.3 rom) (ZRC), Pang1aoIsland; B, paratype female (17.5
by 14.3 rom) (ZRC), Panglao Island.

THE RAFFLES BULLETIN OF ZOOLOGY 2002\:";~("

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Fig. 12. Sesarmoidesboholano, newspecies.Paratypemale(15.1 by 12.3 mm) (ZRC). A, carapace;B, secondambulatoryleg; C, thirdambulatoryleg; D, abdominalsegments4-6 and telson; E-G, left G1 (denuded).Granulesand setaeon structuresomitted. Scales:A-C= 5.0 mm, D = 2.0 mm, E = 1.0 mm, F, G = 0.5 mm.

429

Ng: On the genusSesarmoidesaI., 17 Dec.2000; 2 males (13.9 by 11.8 mm, 15.4 by 13.3 mm)(ZRC), Tawala Cave, Tawala, Panglao, Panglao Island, Bohol,
Philippines, colI. P. K. L. Ng, 17 Dec.2000; 1 male (11.7 by 9.8mm) (ZRC), Virata Cave, Libaong, Panglao, Panglao Island, Bohol,
Philippines, colI. Y. Cai, 18 Dec.2000; 1 male (ZRC), Virata Cave,
Libaong, Panglao, Panglao Island, Bohol, Philippines, colI. P. K.
L. Ng, 18 Dec.2000; 1 male (16.8 by 15.1 mm), 1 female (16.6 by
15.0 mm) (USC), Virata Cave, Libaong, Panglao, Panglao Island,Boho1, Philippines, colI. A. Porpetcho et a1.,17 Apr .-10 May .2001;
2 males (12.9 by 10.1 mm, 12.4 by 10.0 mm), 2 females (14.1 by
11.8 mm, 15.5 by 13.0 mm) (ZRC), Virata Cave, Libaong, Pang1ao,
Panglao Island, Boho1, Philippines, colI. H.-C. Liu & P. K. L. Ng,
27 Nov.2001; 2 males (14.0 by 12.0 mm, 11.3 by 9.8 mm), 2
females (10.5 by 8.8 mm, 10.4 by 9.2 mm) (TMCD), Tawala Cave,
Tawala, Pang1ao,Pang1ao Island, Bohol, Philippines, colI. H.-C.
Liu, 26 Nov.2001; 4 males (12.0-13.9 by 10.1-11.0 mm) (ZRC),
Hinagdanan Cave, northern part of Panglao Island, Bohol,
Philippines, colI. P. K. L. Ng, 30 Nov.2001; 1 female (14.1 by
11.9 m) (ZRC 2001.2313), Hinagdanan Cave, northern part of
Panglao Island, Bohol, Philippines, colI. P. K. L. Ng, 30 Nov.2001;
2 males (12.2 by 10.2 mm, 14.9 by 12.1 mm) (ZRC), caves near
Hinagdanan Cave, northern part of Panglao Island, Bohol,
Philippines, colI. P. K. L. Ng, 29 Nov.2001.

Diagnosis (holotype). -Carapace approximately trapezoidal
in shape; anterior regions well defined, with very short,widely but evenly spaced setae; lateral regions covered withoblique striae; epigastric region pronounced, separated byprominent groove; frontal margin with distinct concave
median emargination; external orbital tooth with tip justreaching level of frontal margin;, outer margin almost
straight, separated from first anterolateral tooth by deep Vshaped cleft; first anterolateral tooth separated from second
anterolateral tooth by small notch. Chelae relatively stout,
fingers subequal to length of palm; ventral margin of pollex
gently concave. Ambulatory legs long, length to width ratiosof meri of second and third legs 3.4 and 3.7 respectively;
dorsal and ventral margins with weak serrations, dorsal
subdistal edge angular but not spiniform; brush-like setae
present on ventral margins of propodus and dactylus of firstleg, usually present on second leg, sparse to undiscernible
on third leg, absent on fourth leg. Prominent tufts of shortsetae between coxae of first to third ambulatory legs. Male
abdomen relatively broad, lateral margins of male telson
gently diverging backwards. G I relatively short, stout, inner
margin almost straight; distal part sharply bent outwards atapproximately right angles, chitinous distal part short.

Remarks. -In general body form and approximate leg
proportions, S. boholano resembles S. guamensis and S.
loyalty. It can easily be distinguished from S. loyalty by its
G 1 possessing an almost straight inner margin (Fig. 12E)
(vs. with a submedian hump, Fig. 6E) and having a relatively
short chitinous distal part of the Gl (Figs. 12E-G) (vs.long,Figs. 6E-G). Compared to S. guamensis,the external orbital
tooth of S. boholano is also more prominently separatedfrom
the first anterolateral tooth by a deeper and more distinct V shaped cleft (Figs. 12A, 15A, B vs. Figs. 14A, 15C, D), theambulatory legs are relatively slightly shorter (Figs. 12B, C
vs. Figs. 14B, C), and the lateral margins of the male telson
are gently diverging backwards (Fig. 12D) (vs. subparallel,
Fig. 14D). The GIs of S. boholano and S. guamensis arevery similar, but that of S. boholano is slightly shorter andmore truncate in shape (Figs. 12F, G vs. Figs. 14F, G).

Sesarmoides
boholanois especiallycommonon the moisterpartsof the caveroof, hiding in the crevicesduring the day.
Many specimenswere observedto haveexcavatedburrows
in the soft earth betweenthe crevices,and are often seen
with only their long second and/or third ambulatorylegs
partially protruding. They have beenobservedto scrapethe
lichens and/oralgae from the rocks.

Sesarmoidesguamensis,new species(Figs. 13, 14, 15C, D, 16C, 17b)
Material examined. -Holotype -male (14.2 by 11.8 mm)(FMNH), in limestonecaveand adjacentlimestonecliffs and beach,
Faifai Beach,near Gun Beach,Tumon Bay, Guam,coli. P. K. L.
Ng et al., 28 JuI.-1 Aug.2001.
Paratypes -8 males (11.7-15.1 by 9.5-12.4 mm), 6 females (15.318.5 by 12.2-14.2 mm) (ZRC), I female (FMNH), I male, I female(QM), same data as holotype.

Paratypes. -Other than in the sexual characters, adultfemalesdiffer from malesin having proportionatelybroader
carapacesand relatively longer ambulatorylegs, especiallythe secondandthird pairs.The notches/cleftsseparatingthe
lateral carapaceteeth are also usually deeperand more
prominent.None of the legs havebrush-like setaeon anyof
the segments.
Etymology. -The species name is derived from local nameused for residents of Bohol. It is used as a noun in apposition.

Colour. -The dorsal surfaceof the carapaceis brown toorangish-brown,with the ventralsurfacesdirty to yellowish
white. The male chelipedsare bright orange,with thoseof
the female paler orange. The ambulatory legs are lightorangish-brown(Fig. 17a).

430

Fig. 13. Sesarmoidesguamensis,new species.A, paratypemale(15.1 by 12.4 mm) (ZRC), Guam; B, paratypefemale (18.5 by
14.2 mm) (ZRC), Guam.

THE RAFFLES BULLETIN OF ZOOLOGY 2002..~"";:,--'."".
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~f

!

B

I

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\

;

A

c
I

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E
G

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Fig. 14. Sesarmoidesguamensis,newspecies.Paratypemale (15.1 by 12.4 mm)(ZRC). A, carapace;B, secondambulatoryleg; C, thirdambulatoryleg; D, abdominal segments4-5 and telson; E-G, left Gl (denuded).Granulesand setaeon structuresomitted. Scales:A-C= 5.0 mm, D = 2.0 mm, E = 1.0 mm, F, G = 0.5 mm.

431

Ng: On the genus Sesarmoide.l
Diagnosis (holotype). -Carapace approximately trapezoidaJ
in shape; anterior regions well defined, with very shortwidely but evenly spaced setae; lateral regions covered witt
oblique striae; epigastric region pronounced, separated b)
prominent groove; frontal margin with distinct concave
median emargination; external orbital tooth with tip n01
reaching level of frontal margin; outer margin almost straight,
separated from first anterolateral tooth by small V -shaped
cleft; first anterolateral tooth separated from second
anterolateral tooth by small fissure. Chelae relatively stout,
fingers subequal to length of palm; ventral margin of pollex
gently concave. Ambulatory legs long, length to width ratiosof meri of second and third legs 3.7 and 4.1 respectively;
dorsal and ventral margins with weak serrations, especiallyventrally, dorsal subdistal edge angular but not spiniform;
brush-like setae present on ventral margins of propodus anddactylus of fIrst leg, usually present on second leg, sparseto occasionally absent on third leg, undiscernible on fourthleg. Prominent tufts of short setae between coxae of first to
third ambulatory legs. Male abdomen relatively broad, lateral

margins of male telson subparallel. G I relatively short, stout.
inner margin almost straight; distal part sharply ben1
outwards at approximately right angles, chitinous distal pm
short.

Paratypes. -In addition to the sexual characters,adultfemales have proportionately broader carapaces andrelatively longer ambulatorylegs,especiallythe secondand
third legs.None of the legs havebrush-like setaeon any of
the segments.The anterior dorsalhalf of the carapacealso
has evenlyspreadout shortsetaethat are usually relatively
longer and more prominentthan those in males.
Etymology. -The speciesis named after its type locality,
Guam.
Colour.-The dorsalsurfaceof the carapaceis light purplishbrown, with the ventral surfaces dirty white. The malechelipedsare bright orange,thoseof the femalebeing palerorange.The ambulatorylegs are purplish-brown(Fig. 17b).

Fig. 15. Carapacesof Sesarmoides.A, S. boholano,newspecies,paratypemale(15.1 by 12.3 mm) (ZRC),PamglaoIsland; B, S. boholano,
new species,paratypefemale (17.5 by 14.3 mm) (ZRC), PanglaoIsland; C,S. guamensis,new species,paratypemale(15.1 by 12.4 mm)(ZRC), Guam; D, S. guamensis,new species,paratypefemale (18.5 by 14.2 mm) (ZRC), Guam.

432

THE RAFFLES BULLETIN OF ZOOLOGY 2002
Remarks. -Sesarmoides guamensis is perhaps closest to S.
boholano, including the form of its GI, but can easily beseparated by several carapace and ambulatory leg characters(see discussion for S. boholano).
Most of the specimens of S. guamensis were obtained fromthe moister parts of the cave roof. Some were observed toscrapethe blue-green algae from the rocks. Several ovigerous
specimens were obtained but the first zoeae could not be
hatched. These females invariably pulled off the eggs fromthe abdomen after a few days in captivity. The eggs are verysmall and the zoeae almost certainly planktonic.

DISCUSSION
In male S. boholano, only the ventral margins of the propodi
and dactyli of the first ambulatory leg are lined with a dense
row of short, stiff setae,resembling a brush; being sparse toabsent in the second and third third ambulatory legs, and arealways absent on the fifth leg. In male S. guamensis, theventral margins of the propodus and dactylus of the firstambulatory leg always have the brush-like setae; on thesecond third ambulatory leg, the brush-like setae are usuallypresent on the ventral margins of the propodus and dactylus,
but is often less dense, and barely discernible in a few
specimens, and on the third ambulatory leg, the brush-likesetae on these articles are usually sparse,sometimes absent.
In S. loyalty, known only from one male specimen, suchbrush-like setae are only present on the first and second
ambulatory legs, being undiscernible on the third and fourth.
In S. balicus and S. sulu, both known only from one male,the brush-like setae are present on the propodi and dactyliof the first and second ambulatory legs but not discernible
on the third. These brush-like setae are always absent on the
fourth male ambulatory legs of all the species discussed
above. They are also absent on all the female ambulatorylegs.
In addition to the presence of the brush-like setae on theambulatory legs, adult female specimens of S. boholano, S.
guamensis and S. sulu also have distinctly broader carapaces
proportionately and relatively longer ambulatory legs (Figs.
7, 9E, F, 11, 13, 15). In the good series of specimens of S.
boholano and S. guamensis examined, females also usually
have slightly longer setae on the anterior part of the dorsal
surface of the carapace and thus appear somewhat moresetose (Fig. 15). In S. sulu on the other hand (but known
from only one heterosexual pair), the carapace setae of themale are more prominent (Figs. 7, 9E, 1:').
Sesannoidesjacksoni is not well known, although the species
is very distinctive with its very long ambulatory legs (cf.
Balss, 1934; Ng, 1988a). The carapace shape and thepresence of setae between the bases of the first to thirdambulatory legs allies S. jacksoni with most of the taxa
treated here, but its more elongate legs (length to width ratio

Fig. 16. Male chelae of Sesarmoides.A, Sesarmoidessulu, newspecies,holotype (18.9 by 15.1 mm) (MZF); B, S. boholano,new
species,paratype(15.1 by 12.3 mm) (ZRC), PanglaoIsland; C,S.
guamensis,newspecies,paratype(15.1 by 12.4mm)(ZRC),Guam.

Fig. 17.Life colours.a,Sesarmoidesboholano,newspecies,Virata
Cave, Panglao,Panglao Island, Bohol, Philippines (photograph:author); b, S. guamensis, new species, Faifai Beach, Guam(photograph:H.-C. Liu). (Specimensnot collected).

433

Ng: On the genus Sesarmoidesof third ambulatory leg 5.1) easily distinguishes it from these.
It is known only from Christmas Island in the Indian Ocean

b. Distinct tufts of setae between coxae of first to thirdambulatory legs
8thus far, primarily from caves, although it is known to wander
outside this habitat (see Ng, 1988a: 186).

6

None of the species of cavernicolous Sesarmoides species
discussed here have the reduced eyes or loss in pigmentation
associated with true troglobites(sensu Guinot, 1988),

a. Ambulatory legs extremely long, third ambulatory leg (merus
to dactylus length) about 4.9 times carapace length [Solomon
Islands]
S. ultrapesb. Ambulatory legs long, but third ambulatory leg (merus
to dactylus) distinctly less than 4.5 times carapace
length7although all have long ambulatory legs. The only species of
Sesarmoides with reduced eyes is S. jacobsoni from Java.
Ovigerous S. guamensis were collected, but no larvae were7

obtained; the specimens having very small eggs. Thus far,larvae are not known for any Sesarmoides species but nospecies is expected to have completely or even partiallyabbreviated development like in Geosesarma species (see8a. Tip of external orbital tooth reaching just beyond level offrontal margin; male tel son equal in length to segment 6[Ambon: Indonesia] .''.'..'.'"
S. cerberus
b. Tip of external orbital tooth not reaching level offrontal margin; male telson shorter than segment 6[New Britain]
S. novabritannia
a. Surface of carapace without obvious oblique striae on

Ng, 1988b). How the species of anchialine or coastal cavedwelling Sesarmoides species release their eggs is still not
known. It is seems likely that some of the species may haveto migrate to the open sea, perhaps like the cavernicolous
gecarcinid Discoplax longipes (see Ng & Guinot, 2001).

posterior branchial region; meri of second to third ambulatory
legs 4.7 and 5.1 times carapace length respectively[Christmas Island: Indian Ocean]S. jacksoni
b. Surface of carapace with clear oblique striae on posterior
branchial region; meri of second to third ambulatory legs

Sesarmoides boholano for example, was obtained in caves
where there were no obvious connections to the sea (e.g.
Virata) as well as in caves with permanent pools (e.g. Tawalaand Hinagdanan) with clear underground connections to theless than 4.5 and less than 5.0 times carapace length
respectively
9a. Meri of first to third ambulatory legs with sharp distal dorsal
spine (Figs. 8B, C) [Palawan: Philippines]
S. sulu

9

open sea.

b.Meri of first to third ambulatory legs without distal dorsal
spine, may be angular but never spiniform

KEY
1

2

3

5

lOa. External orbital tooth truncate, outer margin straight to gently
concave, separated from first anterolateral tooth by

OF SESARMOIDES

b. Ocular peduncle and cornea of normal size and occupying
entirely the orbital cavity
2

prominent, deep V-shaped notch (Fig. 12A) [Bohol:
Philippines]
S. boholano..
b. External orbItal tooth not truncate, outer margIn a1moststraight to gently convex, separated from first anterolateral
tooth by narrow cleft or relatively shallower notch (e.g. Figs.

a. Outer surface of pollex of chela with a distinct longitudinalrow of small conical tubercles, more prominent in males (Fig.
1C)
3

5A, 14A)
11
11 a. G 1 with elongate, slender chitinous distal part (e.g. Figs.
5F, G)
12

b. Outer surface of pollex of chela may be rugose or granulated,
but without longitudinal row of small conical tubercles 5

b. G 1 with relatively short, truncate chitinous distal part (e.g.
Figs. 3F, G)
13

a. Carapace with only 1 epibranchial tooth; length of thirdambulatory leg less than 3 times extraorbit.al width, propod~s
about 2-3 times as long as broad; antenor frontal margInnearly straight; male abdomen with tel son .slightly shorter
than broad at base; length of segment 6 SlIghtly less t~an
twice width [East Africa]
S. longlpes.b.
b. Carapace with 2 epibranchia!
teeth; lengt~ of t.hud
ambulatory leg more than 3 tImes extraorbItal wId.th,
propodus a~out 4 tim.es as long as broad; anterIor
frontal margIn gently SInUOUS;leQgth of segment 6 not

12 a. External orbital tooth separated from first anterolateral toothby very shallow notch (Fig. 6A); length to width ratios ofmeri of second and third ambulatory legs 3.1 and 3.5
respectively (Figs. 6B, C); inner margin of G1 with gentle
submedian hump (Fig. 6E) [Loyalty Islands]
S. loyalty

a. Ocular peduncle short, cornea small, eyes occupying only
part of orbit [Java: Indonesia]
S. jacobsoni

as above

4

TO SPECIES

10

'.'

'

'

'..'

4

External orbital tooth separated from first anterolateral toothby very shallow notch (Fig. 5A); length to width ratios ofmeri of second and third ambulatory legs 3.3 and 3.6
respectively (Figs. 5B, C); inner margin of G 1 almost straight(Fig. 5E) [Bali: Indonesia]
S. balicus.

...13
a. Out~r surface of pollex WIth a 10ngItudm~ row of 8-13 s~all
comcal tubercles; ~dult ma~eabdomen wIth s~gment6 a lIttle
shorter than ?alf Its proxImal breadth [IndIan Ocean an~
Southeast AsIa]
S. kraussla. Length to width ratios of merus of second and thIrd
ambulatory legs 4.3 and 4.0 respectively (Figs. 3B, C); length
to width ratios of propodi of second and third ambulatory
legs 4.1 and 4.5 respectively; G 1 with chitinous distal
part slightly bent downwards (Figs. 3F, G) [Bali:b. Outer surface of pollex with a longitudinal ro,,:, of 3-5 moreelongated tubercles; adult male .abdomen WIth segment 6
sli~htly longer than half proxImal breadth [Southea~t
AsIa]
S. bomeensls

Indonesia]
S. emdib. Length to width ratios of meri of second and third ambulatory
legs 3.7 and 4.1 respectively (Figs. 14B, C); length to width
ratios of propodi of second and third ambulatory legs 3.4

a. No tufts of setae between coxae of first to third ambulatorylegs
6

and 4.2 respectively; G 1 with chitinous distal part bent atright angles (Figs. 14F, G) [Guam]
S. guamensis

434

l

I

THE RAFFLES BULLETIN OF ZOOLOGY 2002
ACKNOWLEDGEMENTS

Her Majesty's Treasury,Invertebratae(London: Smith, Elderand Co.), [1849], pp. 53-71,pis 2, 3.
Man, J. G., De, 1887. Report of the PodophthalmusCrustaceaof
the Mergui Archipelago,collectedfor theTrusteesof the IndianMuseum Calcutta, by Dr. John Anderson, F.R.S.
Superintendentof the Museum.Journal oftheLinneanSocietyof London,1887: 1-317,Pis. 1-19.
Ng, P. K. L., 1988a. A new sesarmine crab of the genus
SesarmoidesSerene and Soh, 1970 (Crustacea Decapoda,
Brachyura, Grapsidae) from Arawe Island, New Britain,
Solomon Sea, with notes on the genus. Micronesica, 21:
181-187,pl. 1.

The author is grateful to Gustav Paulay for his help during
his visits to Guam; and to Wang Chia-Hsiang and Liu HungChang with field collections there. H.-C. Liu is kindly
acknowledged for Fig. 17b. Lawrence Liao, Adonis
Porpetcho and Roxie Diaz Marco (USC) were instrumental
in obtaining specimens from the Philippines. Louis
Deharveng (University of Toulouse) and Marco Vannini(MZF) kindly sent me their sesarmid collections from the
Loyalty Islands and Palawan respectively.

Abele, L. G., 1992. A review of the grapsid crab genus Sesarma(Crustacea: Decapoda: Grapsidae) in America, with thedescription of a new genus. Smithsonian Contributions to
Zoology,527: 1-60.

Ng, P. K. L., 1988b.TheFreshwaterCrabs ofPeninsularMalaysia
and Singapore.Departmentof Zoology, National Universityof Singapore,ShingleePress,Singapore,pp. i-viii, 1-156,Figs.
1-63,4 colour plates.
Ng, P. K. L. & D. Guinot, 2001. On the land crabs of the genus
Discoplax A. Milne Edwards, 1867 (Crustacea:Decapoda:
Brachyura: Gecarcinidae), with description of a new

'i
I
i
ji
i
:'

Balss, H., 1934. Die Krabben der Reise J. W. Harms' nach der
Christmas-Inselund demMalaiischenArchipel. Zoologischer
Anzeiger, 106(10): 225-237.

cavernicolousspeciesfrom the Philippines.RafflesBulletin of
Zoology,49(2): 311-338.
Ng, P. K. L., D. Guinot & T. M. IIiffe, 1994.Sesarmoidesultrapes!i,~Guinot, D., 1988. Les crabescavernicolesdu monde. Memoires
de Biospeologie,15: 3-40.
.Crustacean
HolthuIs,
L. B., 1964. Sesarma (Sesarma) cerberus, a new'new species,a remarkablesesarminecrab from caves in the
Solomon Islands (Decapoda: Brachyura: Grapsidae).
Research 23: 12-22.

J
~
Iii.

cavernicolouscrabfrom Amboina. ZooiogischeMededelingen,40(9): 65-72.
Ihl J E W 1912 U b . kl ' B hSIe, ...,.eer erneerne
rac yurenamm ling ailS
unterirdischenFliissenvon Java.Notes ofthe LeydenMuseum,
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Krauss, F., 1843, Die Sadafrikanischen Crustaceen. Eine
Zusammenstellung aller bekannten Malacostraca,
Bemerkungenaber deren Lebensweiseund geographische
Verbreitung nebst und Abbildung mehrer neuen Arten.
Stuttgart,pp. 1-68, plates 1-4.
MacLeay,W. S., 1838. On the BrachyurousDecapodCrustacea.
Brought from the Capeby Dr. Smith.In: A. Smith,Illustrationsof the Zoology of SouthAfrica; consisting chiefly offiguresand descriptions of the objects of natural history collectedduring an expedition into the interior of South Africa, in the1834 1835
dI836 'HA".Ii
E I . CIA £..' ,h.hope ssoclatlon 0: xp ormg entra ~,I~a: t~get.erwlt
a summary of African Zoology, and an inquiry Into the'geographical ranges of speciesin that quarter of the globe.
Published under the Authority ofthe Lords Commissionersof

Ng, P. K. L. & A. J. Whitten, 1995. On a new cave-dwelling
Sesarmoides(Crustacea:Decapoda:Brachyura: Grapsidae)

I:!

LITERATURE

CITED

fi

years

,

,

an

,

d

Itte

b

out

"T

y

h

"e

C

ifG

ape

0

d

00

from
2 3'

NusaPenida,69-3
6Bali,lndonesia.

TropicaiBiodiversity,

1994,

i
i

( ).3
7.
Rathbun, M. J., 1914. New genera and species of American
bra~hyrhynchouscrabs. Proceedings of the United States
National Museum,47: 117-129,pis. 1-10.
Say, T., 1817-1818.An accountof the Crustaceaof the UnitedStates. Journal of the Academy of Natural Science ofPhiladelphia, 1(1-2): 57-63, 65-80 (pl. 4), 97-101, 155-160,
161-169[1817]; 235-253, 313-319, 374-380, 381-401, 423441 [1818].
Schubart,C. D., R. Diesel & S. B. Hedges,1998.Rapid evolution
to terrestriallife in Jamaicancrabs. Nature,393: 363-365.
R & C L S h 1970 N I d P .fi
II ' dS esarma Say, 1877 (Brac hJura, Decapod a, Crustacea.)
Treubia 27(4): 387-416.
.
Tweedie, M. W. F., 1950. Grapsoid crabs from Labuan andSarawak.SarawakMuseumJournal, 5(2): 338-369.

S'erene,.

..0,

.ew

n

0-

acIIcgeneraa

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to

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I

435