A new genus and new species of the family Paguridae (Crustacea: Decapoda: Anomura), from Hachijo-jima Island, Japan, with a list of hermit crab species found in the same collection sites

13 Pages·2003·8.4 MB·

by  Masayuki Osawa

PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON
116(4):943-955. 2003.
A new genus and new species of the family Paguridae (Crustacea:
Decapoda: Anomura), from Hachijo-jima Island, Japan, with a list of
hermit crab species found in the same collection sites
Masayuki Osawa and Junji Okuno
(MO) Department of Zoology, National Science Museum, Tokyo, 3-23-1, Hyakunincho,
Shinjuku-ku, Tokyo 169-0073, Japan, email: [email protected];
(JO) Coastal Branch of Natural History Museum and Institute, Chiba, 123, Yoshio, Katsuura,
Chiba 299-5242, Japan, email: [email protected]
—
Abstract. A new genus and new species of pagurid hermit crab, Hachijo-
pagurus rubrimaculatus, is described and illustrated on the basis of three spec-
imens from Hachijo-jima Island in the Izu Islands, Japan. The new genus Hach-
ijopagurus appears close to Pygmaeopagurus McLaughlin, 1986, but differs
from the latter in having the eighth thoracic sternite with a pair of ventrally
flattened lobes in male and female, and a rod-like sexual tube on the coxa of
the right fifth pereopod in male. The distinct concavity at the dorsomesial distal
angle of the palm of the right cheliped can be regarded as unique for H.
rubrimaculatus since such the structure has not been described for any known
A
pagurid species. list of the hermit crab species found in the collection sites
of the present new species is provided.
Kato & Okuno (2001) introduced the tion follows that of McLaughlin (1974:9),
richness of the shallow-water decapod crus- with the exception of the posterior carapace
tacean fauna around Hachijo-jima Island of (see Lemaitre 1995:2), fourth pereopod (see
the Izu Islands, Japan, in their local guide- McLaughlin 1997:435), and gill structure
&
book "Shrimps and crabs of Hachijo Is- (see McLaughlin de Saint Laurent 1998:
land", with many underwater photographs. 161). The submedian grooves on the shield
Their book contains a photograph of an un- are termed "paragastric grooves" (see Ko-
usual hermit crab, "Paguridae sp.", taken mai & Osawa 2001:1291). Forest et al.
at the depth of 40 m. The photographed (2000:24) is followed in the interpretation
specimen could be collected, and was found of the ocular peduncle, which is provided
to have a characteristic right cheliped with basally with a small calcified plate referred
a distinct concavity at the dorsomesial distal to as the "ocular acicle". The sternites of
angle of the palm. In addition to this spec- the third maxillipeds and third and fifth pe-
imen, two hermit crabs proved to be con- reopods are each shown as "third",
&
specific with Kato Okuno's (2001) "Pa- "sixth", and "eight" thoracic sternites.
guridae sp." from Hachijo-jima Island were Shield length (si), as measured from the tip
made available for close taxonomic study. of the rostrum to the midpoint of the pos-
The examination of the three specimens re- terior margin of the shield, indicates spec-
vealed that they represent an undescribed imen size. The lengths of the segments of
species that can not be assigned to any the chelipeds were measured along the dor-
known pagurid genera. Thus, we herein de- somesial margin except for the chelae,
scribe and illustrate these specimens as a which were measured along each the dorsal
new genus and new species. midline from the proximal margin of the
General terminology used in the descrip- palm to the level of the distal tip of the
944 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON
fixed finger. The widths of the chelae were pleopods on second to fifth abdominal so-
measured at the dorsoproximal points ofthe mites. Abdomen well developed, dextrally
fingers. The lengths of the segments of the coiled. Uropods markedly asymmetrical.
ambulatory legs were measured along the Telson with midlateral transverse identa-
dorsal margins, but for the propodus, ex- tions on lateral margins; posterior lobes
cluding the proximal oblique margin and with terminal margins separated by shallow
distal projection. The heights of the propodi median cleft. —
and meri of the ambulatory legs were mea- Type species. Hachijopagurus rubri-
sured along the lateral transverse midline. maculatus, new species, by present desig-
The drawings were made with the aid of a nation.
—
drawing tube mounted on a Leica MZ8 ste- Etymology. The genus name is a com-
reomicroscope. The type material of the bination of ''Hachijo'\ meaning the locality
new species is deposited in the Coastal where the type species was collected, and
Branch of Natural History Museum and In- ''pagouros,'' meaning crab in Greek. Gen-
stitute, Chiba (CMNH, with code of ZC), der is mascu—line.
and National Science Museum, Tokyo Remarks. Hachijopagurus shares with
(NSMT, with code of Cr). certain species belonging to the genera
A &
list of hermit crabs found in the col- Alainopagurus Lemaitre McLaughlin,
lection sites of the present new species is 1995, Decaphyllus de Saint Laurent, 1968,
given in "Appendix", with the specimen Iridopagurus de Saint Laurent-Dechance,
&
and collection data. The specimens are de- 1966, Nematopaguroides Forest de Saint
posited in CMNH. Laurent, 1968, Nematopagurus A. Milne-
&
Edwards Bouvier, 1892, and Solitario-
HachijopaguruSy new genus pagurus Tiirkay, 1986, a pair of sexual
— tubes being longer than the coxa of the fifth
Diagnosis. Eleven pairs of biserial, pereopod in male measured on the ventral
phyllobranchiate gills. Shield with moder- surface. Among these genera, Hachijopa-
ately well developed, broadly triangular gurus resembles Nematopaguroides or Ne-
rostrum. Ocular acicles subtriangular, not matopagurus in that the right sexual tube is
elongate. Antennal peduncles with super- slender and distally filamentous, but differs
numerary segmentation. Maxillule with en- from the latter two genera in having mark-
dopod bearing subtriangular external lobe. edly unequal chelipeds in both male and fe-
Third maxilliped with ischium bearing de- male, and unpaired left gonopore in female.
veloped crista dentata and accessory tooth. Species of Nematopaguroides and Nema-
Chelipeds markedly unequal, right much topagurus have subequal or somewhat un-
stronger. Fourth pereopod semichelate, pro- equal chelipeds, and paired gonopores in fe-
podal rasp composed of single row of cor- male (see McLaughUn 1997, 2003; Wang
&
neous scales, dactyl lacking preungual pro- McLaughlin 2000).
cess. Sixth thoracic sternite with semicir- Hachijopagurus rather appears close to
cular anterior lobe. Eighth thoracic sternite Pygmaeopagurus McLaughlin, 1986 cur-
with pair of ventrally flattened lobes. Male rently recognized as monotypic (type spe-
with coxae of fifth pereopods slightly asym- cies: P. hadrochirus McLaughlin, 1986
metrical, right larger; each with sexual tube from Hawaii), in sharing a set of characters
rod-like, distally curved, longer than coxal as follows: eleven pairs of biserial gills;
length measured on ventral surface; 3 un- shield with a moderately well developed,
paired, unequally biramous left pleopods on broadly triangular rostrum; crista dentata of
third to fifth abdominal somites. Female the third maxilliped with an accessory
with unpaired left gonopore; no paired ple- tooth; semichelate fourth pereopods with a
opods; 4 unpaired, unequally biramous left single row of corneous scales in the pro-
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116, 4 945
podal rasp; male with a rod-like sexual tube Hachijopagurus rubrimaculatus
on the coxa of the left fifth pereopod and new species
three unpaired left biramous pleopods; and Figs. 1-3
female with unpaired left gonopore, no pair Paguridae sp.: Kato & Okuno 2001:83, un-
of pleopods modified as goponods on the
numbered
fig.
first abdominal somite, and four unpaired —
left biramous pleopods. However, the shape Type material. Holotype: male (si 1.6
of the eighth thoracic sternite in both male mm), Nazumado, Hachijo-jima Island, Izu
and female and the coxa of the right fifth Islands, 45 m, 25 Nov 2000, SCUBA dive,
CMNH-ZC
pereopod in male immediately distinguish coll. S. Kato, 470. Paratypes: 1
the two genera. The eighth thoracic sternite female (si 1.4 mm), Nazumado, Hachijo-
consists of a pair of ventrally flattened lobes jima Island, Izu Islands, 40 m, 17 Dec
in Hachijopagurus, whereas it is produced 2000, SCUBA dive, coll. S. Kato, NSMT-
as two closely-set lobes in Pygmaeopagu- Cr 14556 [specimen of "Paguridae sp."
rus. The coxa of the right fifth pereopod has photographed by Kato & Okuno (2001)]. 1
a rod-like sexual tube in Hachijopagurus, female (si 1.3 mm), Kyokucho-hama,
but lacks a sexual tube and gonopore in Hachijo-jima Island, Izu Islands, 40 m, 9
Pygmaeopagurus. Jul 2002, SCUBA dive, coll. J. Okuno &
CMNH-ZC
K. Tanaka, 930.
Hachijopagurus is also allied to Anapa- —
Description. Eleven pairs of biserial
gurides de Saint Laurent-Dechance, 1966,
but the structure of sexual tubes in male is phyllobranchiate gills; 2 moderately well to
different in the two genera. Hachijopagurus well developed arthrobranchs on each third
maxilliped to fourth pereopod; single mod-
has a rod-like sexual tube on each the right
erately well developed pleurobranch on
and left coxae of the fifth pereopods, but
seventh thoracic somite.
Anapagurides possesses a pair of short or
Shield (Fig. lA) slightly longer than
very short sexual tubes or only a right tube
broad or slightly broader than long, not
(see Komai 1999:25). On the coxa of the
strongly calcified; anterior margin between
left fifth pereopod, Anapagurides facetus
rostrum and lateral projections concave; an-
(Melin, 1939) from the Ogasawara Islands
terolateral margins sloping; posterior mar-
of Japan has a slightly protruded vas defer-
& gin roundly truncate; dorsal surface weakly
ens (see McLaughlin Sandberg 1995:
convex in general but concave laterally
583); while A. reesei (McLaughlin, 1986)
along conspicuous paragastric grooves,
from Hawaii possesses frequently a vestige
with short setae behind rostrum and lateral
of sexual tube (see McLaughlin 1986:801,
projections. Rostrum moderately well de-
as Nanopagurus McLaughlin, 1986), and A.
veloped, broadly triangular, terminating in
aequalis Komai, 1999 from off Torishima
small spine directed ventrally at slight an-
Island of Japan has a very short sexual tube
gle, overreaching lateral projections, dorsal
(see Komai, 1999:24). surface with weak, short median ridge. Lat-
The monotypic Trichopagurus de Saint eral projections broadly subtriangular, each
Laurent, 1968 (type species: Catapaguro- with small submarginal spine. Accessory
idesl trichophthalmus Forest, 1954 from portions along cervical groove (not illus-
Tahiti) is somewhat similar to Hachijopa- trated) narrow, generally membranous but
gurus, but has quadriserial gills with la- slightly calcified along cervical groove.
mellae weakly divided distally, and a rudi- Posterior carapace membranous, with few
mentary left sexual tube in male (see de tufts of short setae; posteromedian plate
Saint Laurent 1970:210, figs. 11, 16). very weakly calcified, with pair of tufts of
Hachijopagurus has biserial gills, and a short setae in posterior half; cardiac sulci
rod-like left sexual tube. weakly marked, subparallel in anterior half
946 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON
Fig. L Hachijopagurus rubrimaculatus, new genus and new species. Holotype male (si 1.6 mm) from
Hachijo-jima Island, Izu Islands, Japan, CMNH-ZC 470. A, shield and cephalic appendages, dorsal; B, left
mandible, internal; C, same, palp, internal; D, right maxillule (coxal endite missing), external; E, same, lateral;
F, right maxilla, external; G, right first maxilliped (flagellum of exopod missing), external; H, left second max-
illiped, external; I, left third maxilliped, lateral; J, same, ischium and basis, dorsal (internal); K, sixth thoracic
sternite, ventral; L, eighth thoracic sternite, ventral; M, left sexual tube, lateral; N, telson, dorsal. Scales equal
mm.
1.0
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116, 4 947
but divergent in posterior half, extending to arcuate, reaching midlength of fifth pedun-
posterior margin; sulci cardiobranchialis cular segment and overreaching bases of
extending posteriorly along posterior mar- corneas, each terminating in small spine;
gin of branchiostegite. Branchiostegites mesial margin with tufts of moderately long
membranous; anterior margins broadly setae. Antennal flagella (missing in holo-
rounded, unarmed, fringed with short setae. type) approximately 3.0 times longer than
Ocular peduncles (Fig. lA) stout, sub- shield, with 4 short setae distally on every
cylindrical, 0.7 times as long as shield; dor- article.
sal surface with 2 rows of sparse tufts of Mandible (Fig. IB, C) with incisor pro-
short setae mesially; basal portion inflated; cess without distinct teeth on mesial mar-
median portion concave laterally but slight- gin. Maxillule (Fig. ID, E) with external
ly convex mesially; corneas occupying 0.3 lobe of endopod subtriangular, not re-
length of peduncle, not dilated, semispher- curved; internal lobe with apical bristle.
ic, pigmented. Ocular acicles well devel- Maxilla (Fig. IF) with endopod overreach-
oped, subtriangular, each with distinct mar- ing anterior margin of scaphognathite. First
ginal spine terminally, separated basally by maxilliped (Fig. IG) with endopod less than
half basal width of 1 acicle; dorsal surface half length of exopod, exopod inflated
convex; mesial margin with short and mod- proximally. Second maxilliped (Fig. IH)
erately long setae. with basis-ischium fusion incomplete. Third
Antennular peduncles (Fig. lA), when maxilliped (Fig. II, J) with carpus unarmed
fully extended, exceeding ocular peduncles on dorsodistal margin; merus bearing small
by 0.9 length of ultimate segment. Ultimate distolateral spine; ischium with crista den-
segment elongate, 1.8 times longer than tata composed of row of small corneous
penultimate segment, somewhat deeper dis- teeth, accessory tooth small but distinct; ba-
tally, with 3 long setae near dorsodistal sis-ischium fusion incomplete; basis with
margin. Penultimate segment with few few small denticles on mesial margin.
short setae on dorsodistal margin. Basal Chelipeds (Figs. 2A-F, 3A-D) consider-
segment elongate; statocyst lobe produced ably unequal, right much stronger than left.
laterally, with spine on lateral margin; ven- Right cheliped of male holotype (Fig. 2A-
trodistal margin with minute spine and D) massive, dactyl articulating obliquely
short setae. Upper flagellum elongate, with palm, propodal-carpal articulation not
slightly longer than ultimate peduncular twisted. Chela with general outline subov-
segment; lower flagellum reaching mid- ate in dorsal view, 1.6 times longer than
length of upper flagellum. wide; dactyl and fixed finger weakly curved
Antennal peduncles (Fig. lA), when ful- ventrally, each terminating in small corne-
ly extended, exceeding distal margins of ous claw. Dactyl slightly longer than fixed
corneas by approximately half length of finger, 0.9 length of palm; cutting edge with
fifth segments. Fifth and fourth segments rounded calcareous teeth on proximal 0.8
with few scattered, moderately long setae. and small corneous teeth on distal 0.2; dor-
Third segment with few moderately long sal surface convex, with closely-set, small
setae and small spine at ventromesial distal rounded tubercles and several short setae;
angle. Second segment with dorsolateral dorsomesial margin delimited by subacute
distal angle strongly produced, reaching ridge of rounded tubercles; mesial surface
midlength of fourth segment, terminating in with irregular rows of small rounded tuber-
small spine; dorsomesial distal angle with cles along dorsal and ventral margins; ven-
small spine; mesial margin with few short tromesial margin delimited by subacute
setae. First segment with small spine on ridge of rounded tubercles, with several
ventrolateral margin distally; ventrodistal short setae; ventral surface with small
margin unarmed. Antennal acicles slender, rounded tubercles and double row of tufts
948 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON
Fig. 2. Hachijopagurus rubrimaculatus, new genus and new species. A-D, holotype male (si 1.6 mm) from
Hachijo-jima Island, Izu Islands, Japan, CMNH-ZC 470; E, F, paratype female (si 1.4 mm), same locality as
holotype, NSMT-Cr 14556. Right cheliped. A, entire cheliped, mesial; B, same, lateral; C, E, chela, dorsal, setae
omitted; D, F, carpus, dorsal, setae omitted. Scale equals 1.0 mm.
of short setae along cutting region. Palm ally accompanied by tuft of few short setae,
slightly shorter than carpus; dorsomesial palm with weakly elevated longitudinal row
margin subacute, distinctly delimited by of tubercles on midline and extending onto
row of moderately large tubercles, bearing fixed finger along cutting edge; dorsolateral
few short setae, dorsomesial distal angle margin convex, delimited by subacute ridge
with prominent concavity; dorsal surface of of rounded tubercles and low protuberanc-
palm and fixed finger convex, with numer- es, with several short setae; mesial surface
ous small rounded tubercles each occasion- with numerous, small tubercles; lateral sur-
VOLUME NUMBER
116, 4 949
face with numerous, small low protuber- dorsal surface; surfaces with scattered short
ances; ventromesial and ventrolateral mar- setae. Coxa unarmed but with long setae on
gins each delimited by subacute ridge of ventromesial margin. On carpus and merus,
low protuberances; ventral surface with nu- setae on ventromesial and ventrolateral
merous, small low protuberances and tu- margins and ventral face plumose; setae on
bercles, and several short setae, larger pro- other faces and on chela and coxa appar-
tuberances present on longitudinal midline ently simple.
of palm, several tufts of setae present along Right cheliped of each female paratype
cutting region; cutting edge of fixed finger (Fig. 2E, F) smaller than that of male ho-
with low, rounded calcareous teeth on prox- lotype; chela narrower and less tuberculate
imal 0.6 (distalmost tooth well developed) on dorsal surface than that of male holo-
and small rounded calcareous teeth each type, 1.7-1.8 times longer than wide; dactyl
with minute corneous tip on distal 0.4. Car- 0.9-1.0 length of palm; palm 0.7 length of
pus broad, becoming broader distally in carpus, with more strongly elevated, longi-
dorsal view, 1.2 times longer than merus; tudinal median row of larger tubercles ir-
dorsomesial margin depressed, with irreg- regularly arranged in single or double, and
ular row of curved spines accompanied by more strongly elevated dorsomesial and
few short setae, distal part with small tu- dorsolateral margins than those of male ho-
bercles, distal angle produced bluntly; dor- lotype.
sodistal margin unarmed; dorsal surface Left cheliped (Fig. 3A-D) moderately
with short row of curved spines distally on slender, reaching (female paratypes) or not
mesial half, row of curved spines adjacent reaching (male holotype) to proximal mar-
to dorsolateral margin, and scattered small- gin of dactyl of right cheliped; dactyl artic-
er spines and tubercles, each spine occa- ulating obliquely with palm; propodal-car-
sionally accompanied by few short setae; pal articulation not twisted. Chela elongate,
dorsolateral margin weakly delimited, with 3.2-3.4 times longer than wide; dactyl and
irregularly arranged small spines and tuber- fixed finger slightly curved ventrally, each
cles, distal angle produced bluntly; mesial terminating in small corneous claw. Dactyl
face with few scattered short setae, distal slightly longer than fixed finger, 1.2 length
margin with tuberculate ridge; ventromesial of palm; cutting edge with row of sharply
margin protuberant, with tufts of moderate- pointed, small corneous teeth on distal 0.7;
ly long setae; lateral face with small low dorsal surface weakly convex, with few
protuberances, distal margin wich tubercu- very short ridges each bearing short setae
late ridge; ventrolateral margin smooth, dis- along cutting region; dorsomesial margin
tal part produced, subtriangular ventrally, delimited by small low protuberances and
bearing moderately long setae; ventral sur- short transverse ridges each bearing tuft of
face slightly concave, with scattered, mod- few short and moderately long setae, prox-
erately log setae, distal margin without imal part subacute; mesial surface with few
spines or tubercles. Merus subtriangular in very short ridges bearing short and mod-
dorsal view; dorsal surface roundly ridged erately long setae; ventromesial margin
along midline, with row of short transverse rounded; ventral surface with row of tufts
ridge; dorsodistal margin unarmed but with of few short and moderately long setae
row of short setae; mesial face with few along cutting region. Palm 0.5-0.6 times as
short setae; lateral face with few small flat- long as carpus; dorsomesial margin delim-
tened tubercles; ventromesial margin un- ited, with row of irregularly arranged small
armed but with short setae; ventrolateral tubercles and several moderately long setae,
margin with row of small spines on subdis- proximal tubercles spinulose; dorsal surface
tal part and short setae; ventral surface with convex, with elevated row of spines and
few very short setae. Ischium unarmed on spinulose tubercles on midline of palm and
950 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON
Fig. 3. Hachijopagurus rubrimaculatus, new genus and new species. Holotype male (si 1.6 mm) from
CMNH-ZC
Hachijo-jima Island, Izu Islands, Japan, 470. A, left cheliped, mesial; B, same, lateral; C, same,
chela, dorsal, setae omitted; D, carpus of same, dorsal, setae omitted; E, right second pereopod, lateral; F, left
third pereopod, lateral; G, left fourth pereopod, dactyl and propodus, lateral. Scales equal 1.0 mm.
VOLUME NUMBER
116, 4 951
extending onto fixed finger along cutting re- On carpus and merus, setae on ventromesial
gion, tubercles on fixed finger reduced, lat- and ventrolateral margins and ventral face
eral part of fixed finger with irregularly ar- plumose; setae on other faces and on chela
ranged small protuberances and tubercles, and coxa apparently simple.
spines and tubercles accompanied by few Second and third pereopods (Fig. 3E, F)
short or moderately long setae; dorsolateral generally similar from left to right but dif-
margin not delimited; mesial face with ferent in length, right subequal to or slightly
small flattened tubercles and short oblique longer than left; right second pereopod
ridges dorsally; lateral face with small low slightly overreaching tip of right cheliped.
protuberances, short oblique ridges, and Dactyls 1.2 times as long as propodi in sec-
several short and moderately long setae; ond, 1.2 times as long in third, moderately
ventral surface roundly crested on longitu- slender, weakly curved ventrally in lateral
dinal midline, with several short transverse view, straight in dorsal view, each termi-
ridges bearing long and short setae on palm nating in corneous claw; lateral and mesial
and longitudinal double row of irregularly surfaces unarmed but each with shallow
arranged tufts of short and moderately long sulcus along midline and tufts of sparse
setae on fixed finger; cutting edge of fixed short setae along dorsal margin; ventral
finger with row of small calcareous teeth margins each with 6-8 (second) or 6-9
interspersed with very short corneous teeth. (third) slender corneous spines and few
Carpus 1.1-1.2 times longer than merus; short setae. Propodi 1.3 times longer than
dorsomesial and dorsolateral margins each carpi and 3.8 times longer than high in sec-
with row of strong spines and several mod- ond, 1.2-1.4 times longer than carpi and 3.5
erately long setae, spine at each distal angle times longer than high in third; lateral and
largest; dorsodistal margin unarmed; dorsal mesial surfaces with few tufts of very short
surface with few small tubercles; mesial setae along each dorsal and ventral margin;
face with row of small spinulose protuber- dorsal faces weakly protuberant on right but
ances and moderately long setae adjacent to apparently smooth on left, each with row of
dorsomesial margin; lateral face with short sparse, moderately long setae; ventral faces
or very short transverse ridges sometimes each with row of 4-6 small corneous spines
bearing short setae; ventromesial margin and few short setae, spine at distal angle
with few tufts of long setae; ventrolateral largest. Carpi 0.7 length of meri in second,
margin with small tubercles, protuberances, 0.8-0.9 length in third, each with spinule
and tufts of long setae; ventral surface near dorsodistal angle; lateral and mesial
slightly concave, with tufts of long and surfaces with few short setae; dorsal and
moderately long setae. Merus subtriangular ventral faces with sparse setae, setae on
in dorsal view; dorsal surface roundly dorsal face longer. Meri 2.9 times longer
ridged along midline, with few short trans- than high in second, 2.4-2.7 times longer
verse ridges bearing short setae; dorsodistal in third; lateral surfaces apparently naked;
margin unarmed but with row of moderate- ventral margins each with few small pro-
ly long setae; mesial face nearly naked; tuberances, and small spine at each distal
ventromesial margin unarmed but with angle and distal third on second, but un-
transverse tufts of long setae; lateral surface armed on third; dorsal and ventral surfaces
with short and very short transverse ridges; each with row of sparse short and moder-
ventrolateral margin with strong spines dis- ately long setae; mesial faces naked. Ischia
tally, and long and short setae; ventral sur- with short and moderately long setae on
face with several long setae. Ischium un- dorsal and ventral surfaces. Coxae un-
armed on dorsal surface; ventral surface armed, with few tufts of short and moder-
with moderately long setae. Coxa unarmed ately long setae; female with gonopore only
but with long setae on ventromesial margin. on left side.
952 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON
Fourth pereopods (Fig. 3G) subequal in margins oblique, each with 3 small spines
size, semichelate, with scattered tufts of and short setae (male holotype) or appar-
moderately long, simple and plumose setae ently lacking spines but bearing short stiff
marginally. Dactyl moderately curved, with setae (female paratypes), lateral angles
row of tiny corneous teeth on lateral face acute; lateral margins convex, each with
ventrally, no preungual process at base of weakly delimited ridge. —
terminal claw. Propodus with strongly con- Color in flesh specimens. Shield pale
vex ventral margin; propodal rasp com- pink or reddish. Ocular peduncles and aci-
posed of single row of small ovate and lan- cles, antennular and antennal peduncles,
ceolate, corneous scales on distal 0.8 of third maxillipeds, left cheliped, and second
ventral margin. Carpus unarmed on dorsal to fourth pereopods greenish or pale yellow
surface. with scattered small red speckles. Antennal
Fifth pereopods chelate; size of coxae flagella semitransparent with interspaced
(Fig. IL) slightly asymmetrical with right few red articles. Right cheliped pale pink or
larger in male, but equal in female. Male reddish wit—h yellow and orange tints.
with right coxa with membranous, rod-like Habitat. Small gastropod shells, Gyri-
sexual tube approximately 2.2 coxal length neum pusillum (Broderip) or Gyrineum spe-
measured on ventral surface, directed an- cies, family Ranellidae.
—
teriorly; distal part recurved posteriorly, na- Distribution. So far known only from
ked; left coxa (Fig. IM) with membranous, Hachijo-jima Island in the Izu Islands, Ja-
rod-like sexual tube directed ventromesial- pan; 40-45 m.
—
ly, slightly shorter and slenderer than right; Etymology. The specific name is a
distal part recurved posteriorly, naked. combination of the Latin, ''ruber'\ mean-
Third thoracic sternite unarmed on ante- ing red, and ''maculatus'\ meaning spotted,
rior margin. Sixth thoracic sternite (Fig. in reference to the scattered red speckles on
IK) with semicircular anterior lobe slightly most parts of the body.
—
skewed to left and bearing moderately long Remarks. The specimen of "Paguridae
setae on anterior margin. Eighth thoracic sp." depicted in a color photograph by Kato
sternite (Fig. IL) with pair of ventrally flat- & Okuno (2001:83) is a female paratype of
tened lobes separated by shallow median this new species (NSMT-Cr 14556).
depression, each with tuft of short bristles Hachijopagurus rubrimaculatus shows
(male holotype) or moderately long setae intraspecific variations in the structure of
(female paratypes) anteriorly. the right cheliped. The chela and carpus of
Male with 3 left pleopods subequal in the male holotype are broader than those of
size; each endopod 0.3 length of exopod. two smaller female paratypes. The palm of
Female (posterior half of abdomen missing the male is much more tuberculate, has a
in paratype, CMNH-ZC 930) with 4 left less elevated longitudinal row of smaller tu-
pleopods; pleopods on second to fourth so- bercles on the dorsal surface, and less ele-
mites well developed, pleopods on fourth vated dorsomesial and dorsolateral margins
somite slightly smaller than precedences; than those of the females.
pleopod on fifth somite much smaller; an- As noted in the remarks for the genus,
terior 2 pleopods each with endopod half Hachijopagurus resembles Pygmaeopagu-
length of exopod, posterior 2 pleopods each rus. Both H. rubrimaculatus and P. had-
with endopod 0.3 length of exopod. rochirus have relatively large right cheli-
Telson (Fig. IN) with distinct, midlateral peds, but the size is different in comparison
transverse identations on lateral margins in- to the total body mass. The cheliped is men-
dicating division of anterior and posterior tioned to be at least twice the mass in P.
lobes; posterior lobes slightly asymmetrical, hadrochirus (see McLaughlin 1986:790),
separated by shallow median cleft; terminal whereas it is approximately as same as or