A new species of Pseudopaguristes McLaughlin, 2002 (Crustacea: Decapoda: Diogenidae) from Japan

11 Pages·2003·6 MB·

by  Akira Asakura

PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON
116(2):453-463. 2003.
A new species of Pseudopaguristes McLaughlin, 2002
(Crustacea: Decapoda: Diogenidae) from Japan
Akira Asakura and Patsy A. McLaughlin
(AA) Natural History Museum and Institute, Chiba. 955-2, Aoba-cho, Chuo-ku,
Chiba 260-8682, Japan;
(PM) Shannon Point Marine Center, Western Washington University, 1900 Shannon Point Road,
Anacortes, Washington 98221-9081B, U.SA.
—
Abstract. Pseudopaguristes bollandi, a new species of the recently estab-
lished diogenid genus Pseudopaguristes McLaughlin, is described and illus-
trated from Okinawa, Japan. This is only the second species assigned to this
genus.
A
distinctive and unfamiliar hermit crab is no pleurobranch on the thoracic wall
from Okinawa was recently send to the first above the second pereopod. The specimen
author for identification. This specimen su- from Okinawa clearly belongs to Pseudo-
perficially looked very much like a species paguristes and represents a new species de-
of the diogenid genus Paguristes Dana, scribed herein. The holotype is deposited in
1851, particularly in having paired first and the Natural History Museum and Institute,
second pleopods modified as gonopods. Chiba (CBM-ZC). Terminology used fol-
However, the right cheliped was larger than lows McLaughlin (1974) with the exception
the left, a character uncommon in species of the fourth pereopods as defined by
of that genus. Further examination revealed McLaughlin (1997), and gill structure as de-
&
a gill formula aberrant for Paguristes. fined by McLaughlin de Saint Laurent
McLaughlin (2002) recently established (1998). Abbreviations used are; coll., collec-
the new genus Pseudopaguristes, for P. ja- tor; and SL, shield length, measured from
netkae McLaughlin, 2002, a brilliantly col- the tip of the rostral lobe to the posterior
ored and strikingly sexually dimorphic spe- margin of the shield.
cies from Guam, Micronesia. Females of
Pseudopaguristes could easily be assigned Pseudopaguristes bollandi, new species
to the genus Paguristes, because the cheli- Figs. 1-8
peds are similar in size and armature, a char-
—
acter commonly seen in Paguristes. How- Material examined. Holotype: male,
ever, the males differ appreciably in having SL = 3.2 mm, 69 m, Seragaki, Onna-son,
chelipeds quite dissimilar in armature, with Kunigami-gun, Okinawa-hontow, 14 Aug
the right largest. McLaughlin reported that 2000, coll. R. —F Holland, CBM-ZC 6442.
males and females of Pseudopaguristes Description. Eight functional pairs of
share with Paguristes the distinctive char- weakly quadriserial, phyllobranchiate gills
acter of sexually modified pleopods. How- (Fig. lA, B). Shield (Fig. IC) 1.2 times lon-
ever, Pseudopaguristes janetkae has only ger than broad; anterior margin between
eight functional pairs of gills, whereas Pa- rostrum and lateral projections concave; lat-
guristes species have 13 pairs. In Pseudo- eral projections (Fig. ID) triangular, right
paguristesjanetkae, the paired arthrobranchs with small, submarginal, corneous spine,
at the base of the third maxillipeds and che- left unarmed; anterolateral angles (Fig. IE)
Upeds are rudimentary or vestigial, and there each with strong corneous spine (not visible
454 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON
Fig. L Pseudopaguristes bollandi, new species, holotype male (CBM-ZC 6442), SL = 3.2 mm, Seragaki,
Onna-son, Kunigami-gun, Okinawa-hontow. A, arthrobranch gill lamella; B, position and shape of gills; C,
shield and cephalic appendages; D, ocular acicles and anterior portion of shield; E, right lateral view of ocular
peduncle, antenna and anterior portions of branchiostegite and shield; F, left antennule, lateral view; G, left
mm mm
antenna, lateral view; H, antennal flagellum. Scales equal 0.33 (A) and 1 (B-H).
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Fig. 2. Pseudopaguristes bollandi, new species, holotype male (CBM-ZC 6442), SL = 3.2 mm, Seragaki,
Onna-son, Kunigami-gun, Okinawa-hontow. Left mouthparts: A, mandible, external; B, maxillule, external; C,
same, endopod; D, maxilla, internal; E, first maxilliped, internal; F, second maxilliped, external; G, third max-
illiped, external; H, ischium and basis of same, internal. Scales equal 1 mm.
in dorsal view); lateral margins straight; IC, E) very slightly dilated. Ocular acicles
posterior margin truncate; dorsal surface (Fig. ID) with 2 (right) or 3 (left) strong
slightly convex, with scattered tufts of short corneous spines on distal margin; separated
setae and 1 or 2 short ridges laterally. Ros- basally by more than breadth of rostrum.
trum (Fig. ID) prominent, triangular, pro- Antennular peduncles (Fig. IC, F) stout;
duced beyond bases of ocular acicles, with when fully extended, distal margins of ul-
terminal corneous spine. Accessory por- timate segments very slightly exceeding
tions of shield (Fig. IC) small, well calci- distal margins of corneas; ultimate and pen-
fied, unarmed. Branchiostegites (Fig. IE) ultimate segments each with tuft of setae
partially calcified anterodorsally, with row dorsodistally; basal segment with acute
of acute, slender spines, several corneous- spine laterally.
tipped, on dorsodistal and anterodorsal mar- Antennal peduncles (Fig. IC-E, G) mod-
gins. erately long, when fully extended, reaching
Ocular peduncles (Fig. IC) moderately bases of corneas; fifth segment with row of
short, 0.6 length of shield. Corneas (Fig. setae dorsally and laterally; fourth segment
456 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON
Fig. 3. Pseudopaguristes boUandi, new species, holotype male (CBM-ZC 6442), SL = 3.2 mm, Seragaki,
Onna-son, Kunigami-gun, Okinawa-hontow. Right cheliped: A, dorsal; B, mesial; C, lateral; D, dactyl and fixed
finger, ventral; E, fixed finger, dorsal. Scales equal 1 mm.
with strong corneous spine at dorsodistal gle produced, bearing 3 strong corneous
margin and another corneous spine at ven- spines, dorsomesial distal angle with acute
trodistal margin; third segment with prom- corneous spine; first segment unarmed. An-
inent corneous spine at ventrodistal margin; tennal acicles moderately long, straight; lat-
second segment with dorsolateral distal an- erally compressed; dorsomesial and ventro-
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Fig. 4. Pseudopaguristes bollandi, new species, holotype male (CBM-ZC 6442), SL = 3.2 mm, Seragaki,
Onna-son, Kunigami-gun, Okinawa-hontow. Left cheliped: A, dorsal; B, mesial; C, lateral; D, anterior portions
of dactyl (tip broken) and fixed finger, dorsal; E, same, ventral. Scales equal 1 mm.
mesial margins each with row of corneous- lobe with 2 bristles. Maxilla (Fig. 2D) with
tipped slender spines; distal margins each moderately narrow scaphognathite. First
with 3 strong corneous spines; lateral mar- maxilliped (Fig. 2E) with well developed,
gins each with strong, subdistal corneous setose epipod. Second maxilliped (Fig. 2F)
spine. Antennal flagella (Fig. IH) consist- without distinguishing characters. Third
ing of about 15 articles, each article with maxilliped (Figs. 2G, H, 7A) with dorso-
several setae of various lengths. distal margin of carpus bearing acute cor-
Mandible (Fig. 2A) without distinguish- neous spine; merus with ventral margin
ing characters. Maxillule (Fig. 2B, C) with bearing row of slender corneous-tipped
external lobe of endopod recurved, internal spines, and dorsodistal margin bearing
458 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON
acute corneous spine; ischium with well-de- spines and sparse setae on ventromesial
veloped crista dentata, no accessory tooth, margin. Coxa (Fig. 7B) with strong corne-
strong corneous spine at ventrodistal mar- ous spine ventromesially.
gin; basis with few corneous spines. Second pereopods (Fig. 5A-C) similar
Right cheliped (Fig. 3) larger than left. from left to right. Dactyls 1.1 length of pro-
Dactyl 0.4 length of palm; terminal margin podi, each terminating in strong corneous
slightly convex, with very broad corneous claw; mesial faces each with row of cor-
claw (Fig. 3D); dorsal face flat, with scat- neous or corneous-tipped spines dorsally
tered tubercles; cutting edge with 1 strong (Fig. 5B); ventral margins each with row of
and 4 broad, low calcareous teeth. Fixed 9 (left) or 10 (right) strong corneous spines.
finger terminating in small corneous-claw Propodi 1.8 length of carpi, each with row
(Fig. 3E); ventral face with row of 3 cor- of 10 (left) or 12 (right) strong corneous
neous tubercles (Fig. 3D); dorsal face flat, spines on dorsal margin and 1 (right) or 2
with scattered tubercles; cutting edge with (left) acute corneous spines at ventromesial
7 strong calcareous teeth. Palm 1.5 length distal margin (Fig. 5B). Carpi 0.6 length of
of carpus; dorsal surface flat, with scattered meri, each with strong, corneous-tipped,
tubercles; dorsomesial margin with row of slender spine at dorsodistal angle and row
very strong spines; dorsolateral margin with of 5 (left) or 4 (right) slender, corneous-
row of spines. Carpus 0.6 length of merus; tipped spines on dorsal face mesially (Fig.
dorsal face with scattered spines, dorsolat- 5C). Meri with ventral margins each bear-
eral and dorsomesial margins each with row ing acute subdistal spine and row of slender
of very strong spines. Merus with numerous corneous-tipped spines; dorsal margins
spines, some corneous-tipped, on distal half each with proximal row of corneous-tipped
of dorsal face; ventromesial margin with spines. Ischia each with few, slender cor-
strong corneous or corneous-tipped spines; neous-tipped spines dorsally. Coxae (Fig.
ventrolateral margin with row of spines or 7B) unarmed.
tubercles. Coxa (Fig. 7B) with strong cor- Third pereopods (Fig. 6A, B) similar
neous spine ventromesially. from left to right. Dactyls 1.1 length ofpro-
Left cheliped (Fig. 4) with armature podi, each terminating in strong corneous
much weaker than right. Dactyl (terminal claw; mesial faces each with row of small
portion broken off) (Fig. 4D, E) with dorsal corneous spines ventrally (Fig. 6B); dorsal
face flat, bearing few tubercles; cutting margins unarmed; ventral margins each
edge generally straight. Fixed finger termi- with row of 10 (left) or 11 (right) strong
nating in broad corneous claw (Fig. 4D, E); corneous spines. Propodi 1.6-1.7 length of
dorsal face flat, with few tubercles; cutting carpi; dorsal faces unarmed; acute corneous
edge with small, blunt calcareous teeth. spine at each ventromesial distal angle (Fig.
Palm 1.3 length of carpus; dorsal surface 6B). Carpi 0.6 length of meri, each with
flat, with scattered tubercles, dorsomesial strong, corneous-tipped slender spine at
margin with row of strong spines, dorsolat- dorsodistal angle; other portions unarmed.
eral margin with row of spines, some cor- Meri with ventral margins each bearing
neous-tipped. Carpus 0.5 length of merus; small, subdistal corneous spine; dorsal mar-
dorsal face with scattered spines, several gins each with row of corneous spines. Is-
corneous-tipped; ventrolateral and ventro- chia each with few slender, corneous-tipped
mesial margins each with row of spines. spines dorsally and acute corneous spine
Merus with numerous spines, most corne- ventrally. Coxae (Fig. 7B) unarmed.
ous-tipped on dorsal face; ventromesial Sternite of third pereopods (Fig. 7B) with
margin with row of spines, subdistal spine anterior lobe rectangular, unarmed.
sharp; ventrolateral margin with row of Fourth pereopod (Fig. 6C, D) subchelate.
spines. Ischium (Fig. 4B) with row of small Dactyl terminating in strong corneous claw;
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Fig. 5. Pseudopaguristes bollandi, new species, holotype male (CBM-ZC 6442), SL = 3.2 mm, Seragaki,
Onna-son, Kunigami-gun, Okinawa-hontow. A, second right pereopod, lateral; B, dactyl and distal portion of
propodus of same, mesial; C, carpus of same, mesial; D, left uropod; E, right uropod; F, telson, dorsal; G,
posterior lobes of same, ventral. Scales equal 1 mm.
no preungual process; ventral face with 2 Male first pleopods (Fig. 7B-D) paired,
corneous spines slightly laterally. Propodal modified as gonopods; basal lobe bearing
rasp with 2 rows of corneous scales. Carpus few setae at superior mesial angle; inferior
with large dorsodistal spine directed slight- lamella with distal margin bearing row of
ly mesially; ventral face with long, simple short, hooked spines, and lateral margin
setae and clump of long capsulate setae with row of setae; internal lobe with row of
(Fig. 6D). setae on mesial margin; external lobe dis-
Fifth pereopod (Fig. 6E) chelate; dactyl tinctly exceeding inferior lamella in distal
and propodus with well-developed rasps; extension. Second pleopods (Fig. 7B, E, F)
carpus with dorsodistal spine. paired, modified as gonopods; basal seg-
PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON
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Fig. 6. Pseudopaguristes bollandi, new species, holotype male (CBM-ZC 6442), SL = 3.2 mm, Seragaki,
Onna-son, Kunigami-gun, Okinawa-hontow. A, third right pereopod, B, dactyl and distal portion of propodus
of same, mesial; C, fourth right pereopod, lateral; D, carpus and ventral setae of same, mesial; E, fifth right
mm mm
pereopod. Scales equal 1 (A-C, E) and 0.5 (D).
ment naked; endopod with several long se- to fifth left pleopods each with exopod well
tae; appendix masculina strongly twisted; developed, endopod reduced.
lateral and distal margins and inferior face Uropods (Fig. 5D, E) asymmetrical, left
with moderately long setae. Third (Fig. 7G) larger than right; rasps of exopods and en-
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Fig. 7. Pseudopaguhstes bollandi, new species, holotype male (CBM-ZC 6442), SL = 3.2 mm. Seragaki,
Onna-son, Kunigami-gun, Okinawa-hontow. A, third maxillipeds, ventral; B, ventral view of cephalothorax and
anterior portion of abdomen; C, first pleopod, external; D, first pleopod, internal; E, second pleopod, external;
mm mm
F, second pleopod, internal; G, third pleopod. Scales equal 1 (A, B, G) and 0.2 (C-F).
dopods well developed; protopods each cleft, left lobe larger than right, terminal
with row of spines posteriorly. margins fringed with spines.
—
Telson (Fig. 5F, G) with lateral constric- Color in life. Shield white; antennular
tions; anterior portion unarmed; posterior flagella yellow; antennal flagella with alter-
lobes separated by moderately deep median native red and white bands; antennular, oc-
462 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON
RFB#3814-D ^
Fig. 8. Pseudopaguristes bollandi, new species: holotype male (CBM-ZC 6442), SL = 3.2 mm, Seragaki,
Onna-son, Kunigami-gun, Okinawa-hontow. Photo by Robert F. Bolland.
ular and antennal peduncles red; corneas to intraspecific variations, such as observed
yellow; second and third maxillipeds, che- in many hermit crab species. However, with
lipeds and second and third pereopods uni- so few specimens known it is not possible
form red (Fig.—8). to evaluate variability. The minor differenc-
Etymology. This species is named for es in the armature of the ambulatory legs
Professor Robert F. Bolland who collected and telson seen in the males ofthese species
the specimen. — may also reflect simple variability. One dis-
Distribution. Known only from the tinct difference between these two species
type locality—. is seen in the dactyls of the fourth pereo-
Remarks. Morphologically, P. bollandi pods. In P. janetkae a very prominent
new species is quite similar to P. janetkae preungual process is developed at the base
but minor differences are seen between of the claw, giving the dactyl a quasi-che-
them. Although the general shapes of the late appearance. No preungual process is
shield and cephalic appendages are quite present in the holotype and only known
comparable between P. janetkae and P. bol- specimen of P. bollandi.
landi, the majority of the spines of P. ja- Despite their general similarities in mor-
netkae lack the corneous tips found in P. phology, the two species are readily distin-
bollandi. That the dorsal surfaces of the guished in life by differences in coloration
chelae are provided with spines in P. ja- of the ambulatory legs. These appendages
netkae but only tubercles in P. bollandi are uniformly red in P. bollandi, whereas
may be diagnostic, or may be attributable the carpi, propodi and dactyls ofP. janetkae