A new species of hermit crab of the family Parapaguridae (Decapoda, Anomura) from French Polynesia

7 Pages·1998·2.2 MB·English

by  Lemaitre, Rafael

A new species of hermit crab of the family
Parapaguridae (Decapoda, Anomura)
from French Polynesia
Rafaël LEMAITRE
Smithsonian Institution, National Muséum of Natural History,
Department of Invertebrate Zoology,
Washington, D. C. 20560 (United States)
Lemaitre R. 1998. — A new species of hermit crab of the family Parapaguridae (Decapoda,
Anomura) from French Polynesia. Zoosystema 20 (1) : 101-107.
ABSTRACT
A new deep-water hermit crab species of the family Parapaguridae,
Oncopagurus oimos, is described from Moruroa (French Polynesia, Tuamotu
Archipelago). The new species is distinguished primarily by its distinctive
colour pattern (still visible in alcohol-preserved spécimens after one year),
and consisting of broad stripes on the left cheliped and ambulatory legs.
Other diagnostic characters of the new species are: (1) maies lacking first
KF.YWORDS pleopods and having reduced unpaired left second pleopods; (2) slender left
deep-water hermit crab,
cheliped; (3) rounded mesial face of the right chela. The new species is com-
new species,
Parapaguridae, pared to another congeneric species, O. tuamotu Lemaitre, 1994 that also
Oncopagurus, occurs in French Polynesia, as well as to other species of the genus in which
French Polynesia,
Tuamotu Archipelago. maies lack fitst pleopods.
RÉSUMÉ
Une espèce nouvelle de pagure de la famille des Parapaguridae (Decapoda,
Anomura) de Polynésie française. Une espèce nouvelle de pagure d'eau profonde,
appartenant à la famille des Parapaguridae, Oncopagurus oimos, est déctite de
Motutoa (Polynésie française, archipel des Tuamotu). Cette espèce nouvelle
se distingue en patticulier par la couleur (encore visible après un an de
conservation en alcool) des bandes longitudinales sur le chélipède gauche et
les pattes ambulatoires. D'autres caractères distinctifs sont : (1) la présence,
MOTS CLÉS chez les mâles, d'un seul deuxième pléopode gauche ; (2) le chélipède gauche
pagure d'eau profonde,
grêle ; (3) la face mésiale de la pince droite arrondie. Cette nouvelle espèce
nouvelle espèce,
Parapaguridae, est comparée à une autre espèce du genre, O. tuamotu Lemaitte, 1994 qui se
Oncopagurus, trouve également en Polynésie française, ainsi qu'aux autres espèces du genre
Polynésie française,
archipel des Tuamotu. dont les mâles n'ont pas de premiers pléopodes.
ZOOSYSTEMA • 1998 • 20(1) 101
Lemaitre R.
Study of parapagutid samples, obtained from margins sloping; posterior margin broadly roun­
Ftench Polynesia since Lemaitte's (1994) report ded. Rostrum broadly rounded, weakly produ-
on the species of this family from the area, has ced, and with shott mid-dotsal ridge.
revealed the existence of an undescribed species. Venttolateral margins of shield each with small
This new species belongs in the recenrly propo- spine (not visible in dorsal view, and often only
sed genus Oncopagurus Lemaitre, 1996, the spe­ on one side). Anterodistal matgin of branchioste-
cies of which are characterized primarily by: gite rounded, unarmed, serose.
Ocular peduncles more than half length of
(1) présence of upward curved epistomial spine;
shield, with dorsal row of setae. Cotnea weakly
(2) phyllobtanch gills; (3) operculate right chela;
dilated. Ocular acicles subttiangular, terminating
(4) maies having pootly to modetately developed
in strong spine; separated basally by less than
fitst and second pleopods, with first sometimes
basai width of one acicle.
absent (Lemaitte 1996).
In the material examined section, the length of Antennulat peduncle long, slender, exceeding
the shield of the spécimens is indicated in paren- distal margin of cornea by enrire length of ulti-
thesis, measured (to the nearest 0.1 mm) ftom mate segment; venttal flagellum with five to six
the tip of the tostrum to the midpoint of the articles. Ultimate segment twice as long as penul-
postetiot région of the shield. The term "semi- timate segment, with scatteted setae. Basai seg­
chelate" is used for the foutth peteopod in accor- ment with strong ventromesial spine; latéral face
dance with the définition ptovided by with distal subtectangular lobe armed with one
McLaughlin (1997). The spelling of the island or two small spines, and strong spine proximally.
locality whete this new species was found is Antennal peduncle (Fig. 1B) exceeding distal
accotding to Mottelet (1986). A summaty of margin of cornea by about one thitd length of
deep-water collecting activities in Ftench fifth segment. Flagellum long, exceeding exten-
Polynesia, including a list of ctustacean species ded tight cheliped and ambulatoty legs, articles
and station data, can be found in Poupin (1996). with setae less than one to two flagellar articles in
length (Fig. 1C). Fifth segment unatmed, but
with scatteted setae. Fourth segment with strong
Oncopagurus oimos n.sp.
spine on dotsolateral distal angle. Thitd segment
(Figs 1-3)
with strong ventromesial distal spine. Second
segment with dotsolatetal distal angle ptoduced,
MATERIAL EXAMINED. — French Polynesia.
Tuamotu Archipelago, Moruroa atoll, Marara, terminating in strong, simple spine; mesial mar­
stn 499, 21°47,6'S - 138°55,7'W, trapped, 200 m, gin with spine on dorsolatetal distal angle. First
5.V.1996: holotype $ (2.8 mm) MNHN-Pg 5505; segment with unarmed latetal face; ventromesial
paratypes, 1 d (2.4 mm), 1 2 (2.7 mm) MNHN-
angle ptoduced, with three to four small spines
Pg 5506; 1 d (2.9 mm) USNM 276085.
latetally. Antennal acicle slightly curved outward
ETYMOLOGY. — The spécifie name is from the Greek (in dorsal view), at most slightly exceeding distal
oimos, meaning stripe, used as a noun in apposition, matgin of cornea, terminating in strong spine;
and refers to rhe distinctive colour pattern of this spe­ mesial margin with row of eight to thirteen
cies.
spines, setose.
DISTRIBUTION. — Known so far only from Moruroa Mandible (Fig. 2A) with three-segmented palp.
atoll, on the Tuamotu Archipelago, French Polynesia.
Maxillule (Fig. 2B) with extetnal lobe of endo-
Depth: 200 m.
pod weakly developed, internai lobe with long
tetminal seta. Maxilla (Fig. 2C) with endopod
HABITAT. — Gastropod shells.
exceeding distal maigin of scaphognathite. Fiist
maxilliped (Fig. 2D) with endopod exceeding
DESCRIPTION
exopod in distal extension. Second maxilliped
Shield (Fig. 1A) as broad as long; dorsal surface
(Fig. 2E) with exopod about seven times as long
evenly calcified, with scatteted short setae; ante­
as broad. Thitd maxilliped (Fig. 2F) with distal
rior margins weakly concave; latéral projections
rwo segments each twice as long as wide; crista
subttiangulat, tetminating acutely; anterolateral
102 ZOOSYSTEMA • 1998 • 20(1)
New parapagurid from French Polynesia
dentata with about twelve corneous-tipped teeth; (Fig. 1D-F) massive, with sparse setation. Fingers
coxa and basis each .with one tooth mesially. curved ventromesially, each terminating in cor-
Sternite of third maxillipeds with small spine on neous claw; cutting edges with irregularly-sized
FIG. 1. — Oncopagurus oimos n.sp., Marara, stn 499, Moruroa atoll: A-H, holotype S (2.8 mm) (MNHN-Pg 5505); I, paratype S
(2.9 mm) (USNM 276085). A, shield and cephalic appendages; B, right antennal peduncle (latéral view); C, proximal portion of fla­
gellum of same; D, right cheliped (dorsal view); E, right chela of same (ventral view); F, merus and carpus of same (mesial view); G,
left cheliped; H, left second pleopod (arrow) and portion of pleuron (latéral view); I, left second pleopod (latéral view). Stippled areas
on shield (A), merus and carpus of right cheliped (F), and left cheliped (G) indicate reddish colour pattern. Scales bars- A D-G
1 mm; B, C, H, I, 0.5 mm.
ZOOSYSTEMA • 1998 • 20(1)
103
Lemaitre R.
oblique angle to longitudinal axis of palm; mesial of about ten to fourteen corneous spines; latéral
margin broadly curved, well defined by row of and mesial faces with shallow, longitudinal sulcus
spines (corneous-tipped on distal half); dorsal on proximal half (deeper on mesial face).
face with scattered small spines proximally; ven­ Propodus with row of setae on dotsal and ventral
tral face smooth; venttomesial face concave. margins. Carpus with small dorsodistal spine and
Fixed finger broad at base; latéral margin well setae dorsally and ventrally. Merus unarmed,
defined by row of spines (corneous-tipped on with setae on dorsal and ventral margins.
distal half); dorsal face with scattered small Ischium and coxa unarmed. Anterior lobe of
spines or tubercles; ventral face smooth. Palm sternite of third pereopods setose, subsemicircu-
broader than long; latéral margin broadly roun­ lar, armed with simple terminal spine.
ded, well delimited by row of blunt to sharp Fourth pereopod (Fig. 3E) semichelate. Dactyl
spines; dorsomesial margin marked by row of terminating in sharp corneous claw; with ventro­
small spines; mesial face rounded, with small lateral row of small corneous spinules. Propodus
spines or tubercles; dorsal surface smooth except longer than dorsoventral width, rasp formed of
for scattered small tubercles; ventral surface one row of rounded scales. Carpus with long
smooth. Carpus with latéral margin well delimi­ setae on dotsal margin. Merus with rows of long
ted by row of spines; dorsal face with numerous setae on dorsal and venttal margins.
small spines; dorsodistal margin with row of Fifth pereopod (Fig. 3F) chelate. Propodal rasp
spines; ventromesial distal margin slightly expan­ extending to mid-length of segment.
ded mesially, with row of spines; venttal face Uropods and telson (Fig. 3G-I) markedly asym­
with scattered small tubercles. Merus with dorsal metrical. Telson lacking ttansverse suture; dorsal
row of small spines; ventromesial margin with
surface with scatteted setae; terminal margin
row of spines. Ischium with ventromesial row of
with shallow médian cleft separating left and
small spines. Coxa with one or two small spines
tight lobes, each with sevetal marginal corneous
on ventromesial and ventrolateral margins, and
spines.
ventromesial row of setae.
Maie lacking first pleopods; with unpaired redu-
Left cheliped (Fig. 1G) slender, with chela as ced second left pleopod (Fig. 1H, I) consisting of
long as carpus; well calcified. Fingers terminating minute bud or very short segment with few ter­
in small corneous claws; dorsal and ventral sur­ minal setae. Female lacking vestigial second right
faces unarmed except for scattered tufts of setae; pleopod.
cutting edge of dactyl and fixed finger each with
row of minute corneous teeth. Dactyl subequal Colourpattern (Figs 1A, F, G, 3A, B)
to palm in length. Palm unarmed or at most with No observations of colour in life were made of this
inconspicuous tubercle on dorsomesial angle, species. Howevet, after approximately one year in
and scattered setae; ventral face smooth except alcohol, a distinctive reddish colour pattern was
for scattered setae. Carpus with strong dorsodis­ still visible in the spécimens. The shield has two
tal spine; dorsal margin with moderate setation; small reddish spots (Fig. 1A) on the anterior half,
ventral face smooth. Merus with setae on dorsal one just behind each latéral projection. On both
margin; ventrolateral distal matgin with row of chelipeds (Fig. 1F, G), the dorsodistal portions of
spines; ventral face smooth. Ischium unarmed, the meri are reddish. The carpus of the right cheli­
with setose ventral face. Coxa with one spine on ped has a reddish area on the proximal portion of
ventromesial and ventrolateral distal margins, the latéral and mesial faces. The carpus of the left
and ventromesial row of setae. cheliped has a distinctive broad reddish stripe on
Ambulatory legs (Fig. 3A-C) similar from right the dorsolateral and mesial faces; the dotsomesial
to left, teaching approximately to, or just margin of the palm is light reddish; the dactyl is
beyond, tip of extended right cheliped. Dactyl reddish. The ambulatory legs (Fig. 3A, B) have a
slightly less than twice as long-as propodus, ter­ reddish colour dorsodistally on the meri; the carpi
minating in sharp corneous claw; with dotsal and each have a reddish stripe on the latéral and mesial
dorsomesial rows of setae, and venttomesial tow faces, and the stripes of the carpi continue on the
ZOOSYSTEMA • 1998 • 20(1)
104
New parapagurid from French Polynesia
ZOOSYSTEMA • 1998 • 20(1) 105
Lemaitre R.
meri but only on the latéral faces; the dactyls The othet four are O. haigae de Saint Laurent,
have teddish dorsal faces. 1972 (Eastern Pacific); O. orientalis de Saint
Lautent, 1972 (Indo-Pacific); O. tuamotu
Lemaitre, 1994 (known only from the Tuamotu
REMARKS
This new species is the fifth in the genus Atchipelago); and O. cidaris Lemaitte, 1996
Oncopagurus in which maies lack first gonopods. (known only from Austtalia). The maies of thèse
FIG. 3 — Oncopagurus oimos n.sp., Marara, stn 499, Moruroa atoll: holotype d (2.8 mm) (MNHN-Pg 5505). A, left second pereopod
(latéral view); B, lett third pereopod (latéral view); C, dactyl of same (mesial view); D, sternite of third pereopods (ventral view); E, left
fourth pereopod (latéral view); F, propodus and dactyl of left fifth pereopod (latéral view); G, exopod of left uropod (dorsal view);
H, telson (dorsal view); I, exopod of right uropod (dorsal view). Stippled areas on second (A) and third (B) pereopods indicate reddish
colour pattern. Scale bars: A-D, 1 mm; E-l, 0.5 mm.
106 ZOOSYSTEM A • 1998 • 20(1)
New parapagurid from French Polynesia
four species have paired asymmetrical second previously mentioned différences in pleopod
gonopods; however, Lemaitre (1996, 1997) has conditions, othet chatacters can also be used to
documented intra-specific variation in maies of distinguish O. oimos n.sp. from O. tuamotu. The
O. orientalis and O. cidaris, where the second fight mesial face of rhe right palm is rounded in the
gonopod is occasionally lacking. The three known new species, with a weak irregular dorsomesial
maies of O. oimos n.sp. have only reduced, simple row of spines, whereas the mesial face is expan-
unpaired left second pleopods. The segmentation ded distally, and thete is a distinct dorsomesial
of the maie second pleopods in thèse five species and venttomesial rows of spines in O. tuamotu.
differs. The second pleopods are unsegmented in The left chela is noticeably more slender, as long
O. oimos n.sp., O. haigae and O. orientalis; they as the carpus, and the fingers are ser nearly paral
are two-segmented in O. tuamotu; and one- or lel ro the longitudinal axis of the palm in the
two-segmented in O. cidaris. Of ail known species new species; the chela is shorter than the catpus,
of Oncopagurus, O. oimos n.sp. is the only one in and the fingets are ser obliquely (pointing ven-
which females have only unpaired left second tiolaterally) to the longitudinal axis of the palm
pleopods; females of ail othet species have vestigial in O. tuamotu.
tight second pleopods as well.
The distinctive colout pattern of O. oimos n.sp., Acknowledgements
can be used to distinguish it from O. tuamotu, The collecting effot ts of Joseph Poupin in French
the only other congeneric species known from Polynesia have been invaluable in documenting
French Polynesia. The new species has broad the crusracean fauna from rhis area. His efforts
sttipes on the left cheliped and ambulatory legs are gratefully acknowledged. I thank also Alain
(Figs 1G, 3A, B), whereas O. tuamotu has red Crosnier for fosteting this and othet studies
bands on the cheliped and walking legs (see based on the important matetial gatheted during
Lemaitte 1994: 411, fig. 281). In addition to the many récent French expéditions.
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French Polynesia with descriptions of four new mit crabs of the family Paguridae from rhe Karubar
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Campagnes MUSORSTOM, Volume 12, P. (eds), Résultats des Campagnes MUSORS
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Submitted on 30 May 1997;
accepted on 8 September 1997.
ZOOSYSTEMA • 1998 • 20(1) 107