Anomoeomunida, a new genus proposed for Phylladiorhynchus caribensis Mayo, 1972 (Crustacea: Decapoda: Galatheidae)

4 Pages·1993·1.9 MB·

by  K Baba

PROC. BIOL. SOC. WASH.
106(1), 1993, pp. 102-105
ANOMOEOMUNIDA, A NEW GENUS PROPOSED FOR
PHYLLADIORHYNCHUS CARIBENSIS MAYO, 1972
(CRUSTACEA: DECAPODA: GALATHEIDAE)
Keiji Baba
Abstract. —Anomoeomunida, a. new genus, is established for Phylladiorhyn-
chus caribensis Mayo, 1972, and is differentiated from PhylladiorhynchusBaba,
1969, by the presence of male pleopods on the first abdominal segment, the
rostrum bearing a dorsal ridge in midline, the single spine at the distolateral
angle of the antennular basal segment, and the lack of ventral spines on the
sickle-shaped dactyli ofthe walking legs. It is also distinguished from Pleuron-
codes Stimpson, 1860, by the pterygostomial flap not visible from a dorsal
view and the dactyli ofthe walking legs sickle-shaped without ventral spines.
Inapreviouspaper, Baba(1991:484) sug- Etymology.—From the Greek anomoios
gested that Phylladiorhynchus caribensis (unlike, dissimilar) plus Munida, suggesting
Mayo, 1972 from the Caribbean Sea be re- that the genus is different from Munida.
moved from that genus. It was suggested Remarks.—Mayo (1972:526) noted that
m
that the species was close to Pleuroncodes Phylladiorhynchuscaribensisfrom 1 1-38
Stimpson, 1860, from the eastern Pacific in the Caribbean Sea was intermediate be-
but that a new genus was needed. A more tween Galathea Fabricius, 1793, andMuni-
thorough comparison now allows a new ge- da Leach, 1820, and placed it in Phylla-
nus, Anomoeomunida, to be proposed to diorhynchus Baba, 1969. She stressed the
include this species, and be discussed. rostral shape in species of the genus and
amended the generic diagnosis to allow for
the lack of spination on the walking legs,
Anomoeomunida, new genus
and for three rather than four or five ter-
Diagnosis.—K^osXnxvci relatively narrow, minal spines (counting the double mesial
dorsally with rounded low ridge, with well- terminal spines as two) on the basal anten-
developed supraocular tooth on each side. nular segment. Lewinsohn (1982:298) sug-
Lateral limit of orbit with distinct angle in gestedthatthiswesternAtlantic form should
dorsalview. Basal segment ofantennulewith eventually be placed in a new genus. Fol-
3 small terminal spines, mesial one not bi- lowing the examination ofthe type material
fid. Third thoracic stemite with 2 convex- deposited at the National Museum ofNat-
ities on anterior margin, posterior margin ural History, Smithsonian Institution,
contiguous to following stemite on entire Washington, D.C. (USNM 140187-8) ofP.
width. Walkinglegslackingspinesotherthan caribensis, I am inclined to believe that
terminals on merus and carpus; dactylus Lewinsohn was correct.
sickle-shaped, lacking ventral spines. Male Anomoeomunida caribensis has most of
pleopods present on first and second ab- the characteristics ofMunida in the general
dominal somites. striation ofthe carapace and abdomen, and
Gender. —Feminine. shapes ofthe antennular basal segment, an-
Type species.—Phylladiorhynchus cari- tenna and sternum (the anterior portion in
bensis Mayo, 1972. particular). But the lateral limit ofthe orbit
VOLUME NUMBER
106, 1 103
a o
m
Fig. 1. Anteriorpartofcarapace Anomoeomunidacaribensis[=PhylladiorhynchuscaribensisMayo, 1972]:
a, male holotype (USNM 140187), dorsal view, right supraocularspine partlybroken; b, same, left lateral view.
= mm.
Scales 1
&
angled in dorsal view, and the walking legs 6c for P. pusillus; Tirmizi Javed 1980:
with smooth, sickle-shaped dactyli and meri fig. 2E for P. bengalensis; Lewinsohn 1982:
without dorsal spines, differentiate it from fig. Iffor P. integrirostris), while it is a thin
other species ofMunida. scallop with a very small median process in
The unique morphology of the walking P. caribensis (Fig. lb). The male pleopods
legsalso separatesA. caribensisfrom species on the first abdominal somite are absent
of Phylladiorhynchus. The rostrum in spe- from Phylladiorhynchus, but present on the
cies of Phylladiorhynchus is broadly trian- Caribbean species. At my request, F. A.
gular, dorsally excavated, and lacks the dor- Chace, Jr. of the Smithsonian Institution
salridge seeninthe Caribbean species. Mayo examinedthe types ofP. caribensis; he wrote
(1972:523) noted thatthelateral limit ofthe to me that "there definitely is a pair ofap-
orbit in P. caribensis bears a small spine. parently uniramous pleopods inserted lat-
Examination ofthe type material discloses erallyonthe firstabdominal somitebutthey
that this spine can be discernible in dorsal are softandflexible, not stiffenedto perform
view (Fig. 1a), but barely so in lateral view asgonopodslikethoseinlobstersandcrabs,"
(Fig. lb); in Phylladiorhynchus, the lateral (Chace, in litt.).
orbitalangleis sharplyproduced(Baba 1991: Anomoeomunida is also related to the
fig. 4). The distomesial margin of the an- eastern Pacific Pleuroncodes Stimpson,
tennular basal segment in Phylladiorhyn- 1860, which contains two species: P. mon-
&
chusbears double spines(see Miyake Baba odon (H. Milne Edwards, 1837) andP. plan-
1965:fig. 6A for P. ikedai\ Miyake & Baba ipes Stimpson, 1860. Comparative material
&
1967: fig. 6b forP. pusillus; Tirmizi Javed from the Smithsonian Institution of these
1980:fig. 2D for P. bengalensis; Lewinsohn two species was examined: P. planipes—4 S
mm
1982:fig. le for P. integrirostris), while that (12.3-13.3 in carapace length excluding
USNM
of P. caribensis bears a single thin small rostral spine), 1 ovig. 9 (14.0 mm),
spine (Mayo 1972:525, fig. le). The disto- 81336, pelagic at 20-40 miles off" shore,
ventral margin of the first (basal) segment southern LowerCalifornia (Magdalena Bay),
of the antennal peduncle is strongly pro- Mar 1940, coll. & id. E. F. Ricketts; P.
—
duced into an anteriorprolongation in Phyl- monodon 2 S (13.7, 16.3 mm), 2 9 (14.9,
ladiorhynchus (see Miyake & Baba 1965:fig. 17.3 mm), USNM 65710, "Albatross" Sta.
4B for P. ikedai; Miyake & Baba 1967:fig. 3396, off' Panama, 07°32'N, 78°36'W, 474
104 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON
be
iilMli Ilk
a
Fig. 2. Anterior part ofcarapace: a, Pleuroncodesplanipes Stimpson, male (USNM 81336), dorsal view; b,
same, ventral view; c, Pleuroncodes monodon (H. Milne Edwards), female (USNM 65710), dorsal view. Scales
= mm.
1
m, 11 Mar 1891, id. J. E. Benedict [these thebasal antennal segment is perfectlyfused
specimens were reported by Faxon (1895: with the orbit and bears a well-developed,
72) as P. monodon?]. basally wide ventromesial spine (Fig. 2a-c);
Haig (1955:34) suggested that P. mono- the rostrum is spiniform anddorsallyridged
don and P. planipes may be identical but on the midline (Fig. 2a, c); male gonopods
this seems not to be so. The specimens of are present on the first and second abdom-
P. planipes examined have fringes of long inal segments; the dactyli ofthe walking legs
setae on the pereopods, especially on the beara rowofdistinctbut fine ventral spines.
walking legs which suggests a pelagic life as Ofthese characteristics,Anomoeomunida
mentioned by Faxon (1895:72), whereas and most of the known species ofMunida
those of P. monodon do not; also the spi- share the presence oftwo pairs ofgonopods
nation ofthe pereopods is less pronounced and the dorsally ridged spiniform rostrum.
in P. planipes. In P. planipes, the third tho- The basal segment ofthe antennal peduncle
racic stemite is relatively wide, with its lat- is fused with the orbit in both Pleuroncodes
eral margins convergent posteriorly, while and Anomoeomunida, and even in Munida
in P. monodon it is narrow, with an acute speciosa von Martens, 1878.
anterolateral process directed straight for- Pleuroncodes differs most obviously from
ward. Anomoeomunida in the pterygostomial flap
These specimens share the following largely visible in dorsal view, the dactyli of
characteristics: the pterygostomial flap (or the walking legs bearing a row ofsmall ven-
linea anomurica) is largely visible from a tral spines, and the lateral Hmit ofthe orbit
dorsal view (see Faxon 1895:pl. 15: fig. 3; not angled.
Haig 1955:fig. 7); the antennular basal seg-
ment bears three prominent terminal spines
Acknowledgments
(mesial, lateral, and dorsolateral) and an ad-
ditional small spine proximal to the dor- I thank R. B. Manning for the loan ofthe
solateral one (Fig. 2b), as typical inMunida; type and comparative materials in the col-
VOLUME NUMBER
106, 1 105
lection ofthe Smithsonian Institution, and Lewinsohn,C. 1982. Phylladiorhynchusintegrirostris
F. A. Chace, Jr. for examining the types of (Dana) und Lauriea gardineri (Laurie) (Decap-
my oda, Anomura) aus dem nordlichen Roten
Phylladiorhynchus caribensis at request.
Meer.—Crustaceana 42:295-301.
The manuscript benefited from suggestions
Mayo, B. S. 1972. Three new species of the family
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MilneEdwards, H. 1837. HistoirenaturelledesCrus-
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