THE RAFFLES BULLETIN OF ZOOLOGY 2009
THE RAFFLES BULLETIN OF ZOOLOGY 2009 Supplement No. 20: 267–270
Date of Publication: 31 Jul.2009© National University of Singapore

A NEW SPECIES OF ALOX TAN & NG, 1995
(DECAPODA: BRACHYURA: LEUCOSIIDAE)
FROM BALICASAG ISLAND, THE PHILIPPINES
Bella S. Galil
National Institute of Oceanography,
Israel Oceanographic and Limnological Research
P.O.B. 8030, Haifa 31080, Israel
Email: bella@ocean.org.il

Peter K. L. Ng
Tropical Marine Science Institute andDepartment of Biological Sciences, National University of Singapore, Kent Ridge,Singapore 11920, Republic of SingaporeEmail: dbsngkl@nus.edu.sg

ABSTRACT. – A new species of leucosiid crab of the genus Alox Tan & Ng, 1995, is described from thePhilippines. Alox tormos, new species, is distinguished from its 11 congeners by the distinct sculpture of
the dorsal surface of carapace and the distally flaring, petaloid tip of the male first pleopod.
KEY WORDS. – Crustacea, Decapoda, Brachyura, Leucosiidae, Alox, new species, Philippines.

INTRODUCTION
The leucosiid crab fauna of the Philippines has been
extensively studied, including material collected by theAlbatross Expedition (1907–1910) (Tan, 1996), and three
expeditions conducted under the aegis of the Muséum nationald’Histoire naturelle, Paris (1976, 1980, 1985) (Chen, 1989;Galil, 2001a, b, 2003a, b, 2005, 2006). In recent years,
the Philippines National Museum, Philippines Bureau ofFisheries, Muséum national d’Histoire naturelle in Paris,
University of San Carlos, National Taiwan Ocean University,and the Raffles Museum of the National University ofSingapore, have conducted a series of expeditions to thePhilippines. These collections have already resulted in a
number of reports on the leucosiid fauna by Galil & Takeda(2004), Komatsu et al. (2004, 2005) and Galil & Ng (2007,2009).
The genus Alox Tan & Ng, 1995, was established for species
formerly included in Oreophorus Rüppell, 1830, where thecarapace bears mushroom-shaped flattened granules andantennular fossae fully sealed when the basal segment of
the antennule is retracted. Of the 11 Alox species described(Tan & Ng, 1995; Naruse & Ng, 2006; Galil & Ng, 2007;
Ng et al., 2008), only four have been found in the Philippines
thus far: A. rugosum (Stimpson, 1858) (see Tan, 1996), A.
ornatum (Ihle, 1918) (see Chen 1989; Tan & Ng, 1995), A.

bothros Galil & Ng, 2007, and A. chaunos Galil & Ng, 2007(see Galil & Ng, 2007).
Examination of shallow water material collected by hand off
Balicasag Island, Phillipines, disclosed a single specimenthat is described herein as a new species. The specimen
is deposited in the Crustacean Collection of the National
Museum of the Philippines (NMCR). The terms used follow
Tan & Ng (1995), with the measurements (in millimeters)
provided of the carapace length and width, respectively.

TAXONOMY
Alox Tan & Ng, 1995
Alox tormos, new species(Figs. 1–3)
Material examined. – Holotype, male (4.2 × 5.6 mm) (NMCR),
station B5, 9º35.402'N 123º44.315'E, 4 m depth, soft and hard corals,
in drop-off area with caves, Balicasag Island, Biking, Panglao, off
Bohol, central Philippines, coll. 2 Jun.2004.

Description of holotype male. – Carapace subpentagonal,carapace width about 1.3 times length. Dorsal surface ofcarapace prominently sculpted, irregularly surfaced with267

Galil & Ng: A new species of Alox from the Philippines
flattened granules, pitted, resembling coral rubble. Front
narrow, produced, somewhat upcurved, divided into 2 swollen
closely-granulate lobes, separated by deep furrow. Anterior
margin almost vertical. Antennule well developed, basal
antenular segment operculiform, rugose, entirely sealing
subtriangular antennular fossa. Antennae folded in orbital
hiatus without gap. Orbits small, rounded, visible in dorsal

view; when retracted, ocular peduncle nearly seals orbit; outerorbital margin bisutured. External maxillipeds concealing
trapezoid buccal opening, closely set with granules;
endognathal meri visible in anterior view. Anterolateral
margin sinuous, indistinctly rimmed, with pit-like indentation
medially. Subhepatic margin with rounded facet medially,visible in dorsal view. Lateral margins of carapace expanded.
Posterolateral margin with granulate tubercle submedially.
Posterior carapace margin produced, visible in dorsal view,bilobate. Postfrontal median longitudinal ridge narrow,
distinct, separated laterally by deep grooves. Granulelined furrow meandering from postfrontal ridge to distal
posterolateral margin. Branchial regions raised, irregularly
pitted, a pair of granule-rimmed cavities submedially on
anterior margin. Cardiac region surfaced with flattened
granules. Intestinal region raised, well demarcated, distinctly
pitted. Chelipeds subequal, robust, closely and evenly
granulate; chela almond-shaped, upper and lower margins
carinate; fingers as long as palm; propodal finger very highFig. 1. Alox tormos, new species. Holotype male (4.2 × 5.6 mm)(NMCR), colour in life.

Fig. 2. Alox tormos, new species. Holotype male (4.2 × 5.6 mm)(NMCR). A, overall carapace view; B, frontal view; C, face,showing third maxillipeds.

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Fig. 3. Alox tormos, new species. Holotype male (4.2 × 5.6 mm)(NMCR). A, B, right male first pleopod. Scale bar = 1 mm.

THE RAFFLES BULLETIN OF ZOOLOGY 2009
proximally, almost twice height of dactylar finger. Second to
fifth pereiopods stout, short, closely granulate; dactyli slender,longer than propodi, terminating in incurved claw. Thoracic
sternum closely, irregularly granulate, horizontally ridged,ridges interspaced with 3 minutely granulated grooves. Maleabdominal sulcus deep, reaching buccal cavity. Abdomenclosely covered with flattened granules; first and second maleabdominal somites slender, horizontal; third to fifth somites
fused, narrowing distally, more than twice as long as sixth
somite; sixth somite subtrapezoid, lateral margins distinctly
convex; telson laciniate, as long as sixth somite. Shaft of malefirst pleopod (Fig. 3a, b) stocky, nearly straight, subdistallysetose, distally dilate, petaloid, tip pointed. Second malepleopod short, slender, apex scoop-like.
Etymology. – From tormos, Greek for hole; alluding to thepitted appearance of the dorsal surface of its carapace. Used
as a noun.
Colour. – Carapace light brown on all dorsal surfaces;
pereiopods and ventral surfaces white (Fig. 1).
Distribution. – Known only from type location in Balicasag
Island, Panglao, the Philippines.
Remarks. – In the general appearance of the carapace,mouthparts, chelipeds, ambulatory legs and male abdomen,
Alox tormos, new species, closely resembles A. zalion Tan& Ng, 1995 (type locality Kii Peninsula, Japan). However,A. tormos is easily distinguished from the latter in having
prominently bilobate frontal and posterior margins (Fig. 1,2A) (versus weakly so, cf. Tan & Ng, 1995: Pl. 8E, Fig.
13A); a more eroded anterolateral rim (Figs. 1, 2; Tan & Ng,
1995: Pl. 8E, F, Fig. 13A); the distal part of fused abdominal
somites 3 to 5 is relatively more slender (cf. Tan & Ng,1995: Fig. 13J); and the structure of the male first pleopod
is distally flaring and petaloid (Fig. 3), rather than bulbous(cf. Tan & Ng, 1995: Fig. 13I).

ACKNOWLEDGEMENTS
The 2004 Panglao Expedition was conducted as a joint
exercise between the Musèum national d’Histoire Naturelle(MNHN, Paris), University of San Carlos, Bureau ofFisheries and Research (BFAR, Manila), National Museumof the Philippines (NMP, Manila), National Taiwan Ocean
University, Keelung, and the National University ofSingapore. Thanks are due to Philippe Bouchet (MNHN),
Danilo Largo (USC) and Marivene Manuel-Santos (PNM)
for all their kind help. The kind financial assistance of theTOTAL Foundation is kindly acknowledged. The study hasbeen partially supported by a research grant (R-154-000334-112) from the National University of Singapore. The
first author thanks a Raffles Museum research fellowshipfor funding her stay in Singapore.

LITERATURE CITED
Chen, H., 1989. Leucosiidae (Crustacea, Brachyura). In: J. Forest(ed.), Résultats des Campagnes MUSORSTOM, Volume 5.
Mémoires du Muséum National d’Histoire Naturelle, Paris(A), 144: 181–263.
Galil, B. S., 2001a. A revision of the genus Arcania Leach,
1817 (Crustacea: Decapoda: Leucosioidea). ZoologischeMededelingen, 75(11): 169–206.
Galil, B. S., 2001b. A revision of Myra Leach, 1817 (Crustacea:Decapoda: Leucosioidea). Zoologische Mededelingen, 75(24):409–446.
Galil, B. S., 2003a. Four new genera of leucosiid crabs (Crustacea:Brachyura: Leucosiidae) for three new species and nine species
previously in the genus Randallia Stimpson, 1857, with aredescription of the type species, R. ornata (Randall, 1939).
Proceedings of the Biological Society of Washington, 116(2):395–422.
Galil, B. S., 2003b. Contribution to the knowledge of Leucosiidae
II. Euclosia gen. nov. (Crustacea: Brachyura). ZoologischeMededelingen 77(20): 331–347.
Galil, B. S., 2005. Contribution to the knowledge of Leucosiida
III. Urnalana gen. nov. (Crustacea: Brachyura). Zoologische
Mededelingen 79(2):9–40
Galil, B. S., 2006. Contributions to the knowledge of Leucosiidae
VI. Soceulia gen. nov. (Crustacea: Brachyura). Zoologische
Mededelingen, 80(6): 71–79.
Galil, B. S. & P. K. L. Ng, 2007. Leucosiid crabs from Panglao,
Philippines, with description of three new species (Crustacea:Decapoda: Brachyura). Raffles Bulletin of Zoology, Supplement
No. 16: 83–98.
Galil, B. S. & P. K. L. Ng, 2009. Calappoidea and Leucosioidea(Crustacea: Decapoda: Brachyura) from Luzon, Philippines,
with descriptions of two new species of Mursia. Zootaxa,2085: 45–60.
Galil, B. & M. Takeda, 2004. On a collection of Mursia (Crustacea,Decapoda, Brachyura, Calappidae) from Balicasag Island,
Philippines. Bulletin of the National Science Museum, Tokyo(A), 30(1):23–35.
Ihle, J.E.W., 1918. Die Decapoda Brachyura der Siboga-Expedition.
III. Oxystomata: Calappidae, Leucosiidae, Raninidae. SibogaExpeditie 39b2: 1–322.
Komatsu, H., M. R. Manuel & M. Takeda, 2004. Some rare
leucosiid crabs (Crustacea, Decapoda, Brachyura) from thePhilippines, with description of a new species of the genus
Arcania. Biogeography, 6: 75–86.
Komatsu, H., M. R. Manuel & M. Takeda, 2005. A small collectionof leucosiid crabs (Crustacea; Decapoda; Brachyura) from
Balicasag Island, Bohol, Philippines. Species Diversity, 10:105–123.
Naruse, T. & P. K. L. Ng,. 2006. Two new species of leucosiid
crabs (Decapoda: Brachyura) from the Ryukyu Islands, Japan.
Crustacean Research, 35: 108–116.
Ng, P. K. L., D. Guinot & P. J. F. Davie, 2008. Systema
Brachyurorum: Part I. An annotated checklist of extant
brachyuran crabs of the world. Raffles Bulletin of Zoology,
Supplement No. 17: 1–286.
Rüppell, E., 1830. Beschreibung und Abbildung von 24 Artenkurzschwänzigen Krabben, als Beitrag zur Naturgeschichte
des rothen Meeres, Gedrukt und in Commission bei Heinrich
Ludwig Brönner. 28 pp., 6 pls. Frankfurt.

269

Galil & Ng: A new species of Alox from the Philippines
Stimpson, W., 1858. Prodromus descriptionis animalium
evertebratorum in expeditione ad Oceanum Pacificum
Septentrionalem missa, C. Ringgold et Johanne Rodgers ducibus,
observatorum et descriptorum. Pars VI. Crustacea Oxystomata.
Proceedings of the Academy of Natural Sciences of Philadelphia,
10: 159–163 [57–61].
Tan, C. G. S., 1996. Leucosiidae of the Albatross expedition tothe Philippines, 1907–1910 (Crustacea: Brachyura: Decapoda).
Journal of Natural History, 30: 1021–1058.

270

Tan, C. G. S. & P. K. L. Ng, 1995. A revision of the Indo-Pacificgenus Oreophorus Rüppell, 1830 (Crustacea: Decapoda:Brachyura: Leucosiidae). In: B. Richer de Forges (ed.), Les fonds
meubles des lagons de Nouvelle Calédonie (Sédimentologie,benthos). Etudes & Thèses, volume 2, ORSTOM: Paris:
101–189.