Crabs Of The Family Homolodromiidae (Crustacea, Decapoda, Brachyura), V-Dicranodromia Spinosa, A New Species From The Western Atlantic

7 Pages·1994·2 MB·English

by  J W Martin

PROC. BIOL. SOC. WASH.
107(3), 1994, pp. 451-457
CRABS OF THE FAMILY HOMOLODROMIIDAE
(CRUSTACEA: DECAPODA: BRACHYURA),
V. DICRANODROMIA SPINOSA, A NEW SPECIES
FROM THE WESTERN ATLANTIC
Joel W. Martin
Abstract.—A new species ofthe primitive homolodromiid crab genus Di-
cranodromia, D. spinosa, is described from amongthe specimens examinedby
M. J. Rathbun (1937) and previously considered to belong to the species D.
ovata A. Milne Edwards. The new species is represented by 10 known speci-
mens, one ofwhich was formerly a paratype ofD. ovata A. Milne Edwards,
all collected in the western Atlantic. The species is easily distinguished from
the other two American species, D. ovata and D.felderi, bythe overall size, by
the spination and setation ofthe carapace and pereiopods, and by the relative
lengths ofthe terminal segments ofpereiopod 5.
At the time ofpublication ofM. J. Rath- tion, Washington, D.C. (USNM), and were
bun's fourth and final volume on the crabs previously labeled Dicranodromia ovata.
ofAmerica (Rathbun 1937), the genus Di- Type material of D. ovata was borrowed
cranodromiaA. MilneEdwards, 1880, con- fromtheMuseumofComparativeZoology,
tained four species: D. ovata A. Milne Ed- Harvard University (MCZ) (the holotype
MCZ
wards, D. mahieuxii A. Milne Edwards, D. female, 6510, and two female para-
MCZ
doederleiniOrtmann,andD. baffini(Alcock types, 6511 [herein reassigned to the
&Anderson). Only one ofthese species was new species] and MCZ 2745), and the Mu-
known from the Americas: Dicranodromia seumnationald'Histoirenaturelle,Paris(the
MNHN
ovataA. MilneEdwards, 1880,thetypespe- third female paratype, MP-
cies ofthegenus. Thetotal numberofspec- B24324). Illustrations were made with the
imens ofD. ovata known to Rathbun, in- aid of a Wild M5APO dissecting stereo-
cluding the four specimens that comprised scope and drawing arm. The abbreviation
thetypeseries(seeMartin 1990),apparently CL indicates carapace length.
was 14. In my description of a second
American species of Dicranodromia from Dicranodromia spinosa, new species
the westernAtlantic, D.felderi, I noted that Figs. 1, 2
several lots among those labeled D. ovata
Dicranodromiaovata.—MiXne.Edwardsand
in the collections ofthe National Museum
Bouvier, 1902 (in part) [see discussion].
of Natural History appear to contain un-
Dicranodromia ovafa.—Rathbun 1937:60,
recognized species (Martin 1990). One of
tsheonsteedsbpeycimeoss,tcuorfitohueslsypeocniemetnhsateixsamreipnreed- f1i3g,. 1fi5g,s.ta3b,le4.1N6o(tinDpiacrrtaonnoldy)r,omainadopvlaattae
A. Milne Edwards, 1880.
and discussed by Rathbun, is described
herein. Maleholotype.-USNM68887,male,CL
Specimensuponwhichthisreportisbased (carapace length) = 6.1 mm. State Univer-
areintheholdingsoftheNationalMuseum sity ofIowa Biological Expedition to Flor-
of Natural History, Smithsonian Institu- ida Keys and the West Indies, Station 63.
452 PROCEEDINGSOFTHEBIOLOGICALSOCIETYOFWASHINGTON
Handwritten labels state "26767" and "abd. mature female, CL = 6.5 mm. Florida, off
drawn" [abdomen drawn; the telson ofthis Key West, 24°15'00"N, 82°13'00"W, 152-
specimen was figured on p. 61 ofRathbun 229 fm (278-419 m), 1877-1878, "Blake"
1937]. Station 5. Accordingto Rathbun (1937, 64:
Type locality.—There are no additional table 16) this is a figured paratype of D.
USNM
data in the vial containing 68887. ovata, although not figured by her. This
However, in Rathbun's (1937) table ofma- specimen is herein reassigned to Dicrano-
terial ofD. ovata (p. 64), there is only one dromia spinosa.
—
male listed as being from the State Univer- Diagnosis. ^vcidiW species, known speci-
mm
sity of Iowa collections, and the station mensnotexceeding 10.1 totalcarapace
numbergiven in the table is 63, which cor- length (including rostral horns). Carapace
USNM
responds to the label in 68887. covered with small spinules interspersed
Therefore,thetypelocality,fromRathbun's with simple, short setae; spinules often lon-
table 16, is "Off American Shoal Light gerand sharperalonganterolateralborders.
[Horida, U.S.A.], N. by E. Vi E. about 8 Rostral horns broad, blunt, with spinules
mi.," from a depth of 85-95 fm (156-174 dorsally and occasionally extending ven-
m), 29 Jun 1893, from "under simple as- trally (not visible in dorsal view). Postor-
cidian" (Rathbun 1937:64). bital tooth small, usually compound. Che-
Designated paratypes.—USiNyi 57068, lipeds andpereiopods 2 and 3 coveredwith
female, CL = 6.9 mm, clearly mature (but minute spinules and long, plumose setae.
notovigerous). StateUniversityofIowaBi- Propodus of pereiopod 5 extremely short,
ological Expedition toFlorida Keys andthe less than twice length ofdactylus.
West Indies, Station 35, 21 Jun 1893, 5 mi Description.—Carapace (Fig. lA-C) in-
N.N.W. Sand KeyLight, 90 fm (165 m), off flated, strongly convex in cross section and
Key West, Florida. USNM 68914, female lesssofromfronttoback;coveredwithsmall
(not ovigerous, as indicated on label and in blunt-tip spines, among which are short,
table 16 ofRathbun 1937, so possibly eggs simple, amber-colored setae. Rostral teeth
lost at some time in past), CL = 7.1 mm, broad and spinose dorsally; some speci-
State University of Iowa Expedition, Sta- mens with spines extending ventrally from
tion 64, offAmerican ShoalLight, N. byW. midpoint between rostral teeth. Carapace
about 8 mi, "about 1 10 fathoms" (201 m), spines becoming slightly smaller posteri-
USNM
29 Jun 1893. 57069, female (ovi- orly,andmoreorlessabsentinbroadregion
gerous), CL = 9.2 mm [9.8 mm according just posterior to cervical groove, presum-
to Rathbun 1937:61], State University of ably because fourth and fifth pereiopods
Iowa, Station 52, American Shoal Light, 10 contact carapace here. Postorbital tooth
mi. N by W 1/2 W., 105 to 1 10 fm (192-201 small, extending laterally to just beyond
m), 27 Jun 1893. This specimen photo- cornea, andusuallybifid orcompound(Fig.
graphed as D. ovata in Rathbun (1937, pi. IC). Region between rostral horns slightly
13, figs. 3,4). depressed. Eyes large relative to carapace;
Additional material (not paratypic).— eyestalk with several blunt spines on fron-
USNM
68917, female (damaged), oviger- todorsalsurface. Thirdmaxillipedswithnu-
ous, CL =7.8 mm [label states "2 females merous spines, especially on external sur-
(1 ovig)" but only 1 crab, an ovigerous fe- face ofmerus. Chelipeds (Fig. 2A) covered
male, found]. USNM 68862, 2 females, CL with spines and with long, lightly plumose
= 5.4 mm (juvenile); CL =10.1 mm (ma- setae; each setaextendingoutward forsome
USNM
ture female). 68917, female (dam- distance before bending rather abruptly to
aged), CL = 7.8 mm. USNM 68877, female create protective layer of horizontally-ori-
(ovigerous),CL= 9.8 mm. MCZ6511,small ented setae around chela. Dactylus with
VOLUME 107, NUMBER 3 453
'":'.;/'Cv;^^-l,
:^:52^^v:?^
'.' ''' :-''-^f-ff^
<4.
T'- '' / '^'''< i"
'"-'•''"*• \:i-'^'%
J-
r--^
' / • . .\.--^i'
:'::^-'4^:;^
Fig. 1. Dicranodromia spinosa, new species, holotype male, USNM 68887. A, dorsal view ofcarapace,
spination illustrated for right side only; B, lateral view of frontal region of carapace and orbit; C, higher
magnification ofanteriorright side ofcarapace showingdetails ofspination ofpostorbital tooth and carapace
along lateral surface; D, anterior part ofcarapace ofDicranodromia ovata A. Milne Edwards, 1880, female
holotype(MCZ6510); E, dorsal viewofholotypemale ofDicranodromiaspinosa, illustratedatsame magnifi-
D
cation as forsizecomparison.
smallbasaltooth.Fixedfingerwith4round- midpoint ofdactylus and to approximately
edteeth,distalmostofwhichisbifidtoallow basal V4 offixed finger. Pereiopods 2 and 3
insertion of opposing tip of dactylus (Fig. (e.g..Fig. 2B)similarlyspinose,coveredwith
2A).Tipsoffingersbonewhite,glossy; hand same lightly plumose setae seen on che-
light brown or tan, with color extending to lipeds. Dactylus (Fig. 2C) stout, recurved,
454 PROCEEDINGSOFTHEBIOLOGICALSOCIETYOFWASHINGTON
Fig. 2. Dicranodromiaspinosa, new species: A, rightchela, outerview; B, third pereiopod(secondwalking
leg) [noteorientationofdactylustopropodusandcoveringofspinesand plumosesetae]; C, samepereiopodas
B,turnedapproximately90°toshowventralmarginofdactylus;D,firstpleopod,rightside,posteromesialview;
E,dactylusandpropodusofleftfourthpereiopod;F,dactylusandpropodusofleftfifthpereiopod.Dicranodromia
ovata A. Milne Edwards, 1880, female holotype (MCZ 6510): G, dactylus and propodus offifth pereiopod
(setation omitted) [note relative lengthsofpropodusanddactylusascomparedtothosein F].
VOLUME 107, NUMBER 3 455
with 6-7 sclerotized spines along ventral (the holotype is in poor condition, making
border. Pereiopods 4 (Fig. 2E) and 5 (Fig. further measurements difficult; see Martin
2F) short, stout. Dactylus of pereiopods 4 1990), and D. felderi reaches a carapace
mm
and 5 strong, recurved, distally sclerotized, length of32 (Martin 1990).
with 3-4 teeth along formerventral border. The possibility that the new species con-
Propodus ofpereiopods 4 and 5 relatively sists merely ofyoung or juvenile forms of
short, clearly less than twice length ofdac- either ofthe previously recognized species,
tylus, and with distal circlet ofstrong, dis- with a loss ofspination and setation as the
tally sclerotized spines; these spines more crabs grow larger, was considered. It is true
numerous, andmore similarly sized, onpe- that the larger ofthe specimens listed here
reiopod 5 (Fig. 2F). Male abdomen andtel- as D. spinosa have relatively smaller and
son spinose [not smooth as indicated in fewercarapacialspines. However, the small
mm
Rathbun's (1937) fig. 15], and without ter- (6.1 CL) holotype of D. spinosa is a
minal setae showninthatillustration. Male mature male, as evidenced by the form of
first pleopod (Fig. 2D) two-jointed, heavy, the first male pleopod (Fig. 2D). Addition-
with deep groove along most of length of ally, several ofthe D. spinosa females are
distalmost article, which bears densetuft of clearly mature, despite their size, with well
setae distally; entire pleopod more or less developed pleopods bearing eggs in some
typicalforthefamily(e.g., seeMartin 1990, cases, lending support to recognition of a
Baez& Martin 1989). small species as opposed to a series ofju-
Etymology. —From the Latin "spina" veniles. In contrast, one ofthe MCZ para-
(thorn) inreference to theratherdense cov- types ofD. ovata(MCZ 2745) (andthe only
ering of small spines on the carapace and MCZ paratype that is, in my estimation,
pereiopods. truly D. ovata) is an immature female, the
abdomenandpleopodsnotyethavingtheir
adult shape or setation, although the cara-
Discussion pace length ofthat crab is 10.4 mm, larger
All four species ofthe genus Dicranodro- than any specimen of D. spinosa. Finally,
mia known to Rathbun (1937) were de- therelativelengthsofthedactylusandprop-
scribed prior to 1890; a fifth species ofDi- odus of the fifth pereiopod differ rather
cranodromia was described 100 years later markedly between D. spinosa and eitherD.
(Martin 1990). Only two of these species, ovata (compare Fig. 2F to fifth pereiopod
D. ovata A. Milne Edwards and D. felderi ofD. ovata holotype, Fig. 2G) or D.felderi
Martin, were previously known from the (see Martin 1990). An error exists in my
western Atlantic. Recently, Guinot (1993) 1990 paper, where thefourth pereiopod of
described two more species ofDicranodro- the holotype female of D. ovata (Martin
mia: D. karubar, from Indonesia, and D. 1990: fig. 5f) was incorrectly referred to in
foersteri, from the Chesterfield Islands. the figure legend as the fifth pereiopod.
Dicranodromia spinosa is rather easily Although a decrease in overall spination
separated from the other two western At- of the carapace and pereiopods might be
lantic species, D. ovataandD.felderi, by its explained as an ontogenetic phenomenon,
relatively small size and by the spination itislesslikelythatallometricchangesinthe
andsetationofthecarapaceandpereiopods. relativelengthsofpereiopodsegmentscould
The largest specimen attributable to D. spi- beexplainedasnormalontogeneticchanges.
nosa is but 10.1 mm total carapace length Milne Edwards & Bouvier(1902) includ-
USNM
(the larger of two individuals in edtextfigures(theirfigs. 5 and 6)andplates
68862). Incontrast,theholotypeof£). ovata (pi. 2 figs. 1-16; pi. 3 figs. 1^), but it is
mm
was originally measured as being 26 difficult to determine which figures were
L
456 PROCEEDINGSOFTHEBIOLOGICALSOCIETYOFWASHINGTON
taken from which specimens, and their il- viously believed, is known from only two
lustrations are too stylized to determine specimens (possibly three; the paratype
whether a given drawing is ofD. ovata or housed at the Museum national d'Histoire
D. spinosa. naturelle, Paris, France [MNHN MP-
In light ofthe morphological differences B24324], from offHavana, Cuba, is dam-
andnearlythreefoldsizedifferencebetween aged and can notwith certaintybe assigned
specimens of D. spinosa and the holotype to either species), and is known only from
of D. ovata (MCZ 6510), it is somewhat deeper waters (greater than 274 m) in the
surprisingthatRathbun(1937)madenoref- Lesser Antilles.
erence to morphological variation orto dif-
ferencesinlifehistoryparameters(i.e.,mat- Acknowledgments
uration at a very small size). Indeed, in the
type series alone, the difference in CL be- I thank R. B. Manning for the loan of
tween mature specimens is more than four- specimens, Daniele Guinot for advice and
mm MCZ encouragement, and Cora Cash-Clark for
fold (26 for the holotype, 6510,
vs. 6.1 mm for MCZ 6511). Because Rath- assistance in the laboratory. This publica-
bun referred to several specimens ofZ). spi- tionisthe fifth inaseriesonhomolodromi-
nosa in her written description ofD. ovata id crabs that was facilitated by a Smithson-
(e.g., Rathbun 1937:61, where she treated ian Institution Office of Fellowships and
USNM 57069 [now a paratype of D. spi- Grants Short-Term Visitor Award I re-
nosa] as a mature female ofD. ovata), it is ceivedinJuly 1989.1thankG.andS. Graves
clear that her description of D. ovata in- for their kind assistance with logistics dur-
cludesaconglomerateofcharactersofthese ing that visit.
twospecies,andisthusofverylimitedvalue
in identification of species of Dicranodro- Literature Cited
umrieas. oTfheMislanmeeEidswtarruedsfor&thBeouevxiceelrle(n1t90fi2g:- BaezR.H,oPm.,ol&oJd.rWo.mMiairdtaien,.I.1D9e8s9c.riCprtaibosnooffthtehefammailley
plate II, figs. 1-16), which included figures ofHomolodromia robertsi Garth, 1973, based
ofthe holotype as well as the paratypes, at onspecimensfrom deepwatersoffthecoastof
least one ofwhich is now attributable to D. Chile.—Journal ofCrustacean Biology 9:492-
500.
spinosa.
Guinot, D. 1993. Donnes nouvelles sur les crabes
In addition to the specimens described primitifs(CrustaceaDecapodaBrachyuraPodo-
herein as D. spinosa, all ofwhich were part tremata).—ComptesRendusde1'Academicdes
ofthe seriesavailableto Rathbun, there are Sciences, Paris 316:1225-1232.
at least two more lots housed at the USNM Martin,J.W. 1990. CrabsofthefamilyHomolodro-
currently labeled D. ovata but belonging to miidae, II. Dicranodromiafelderi, new species,
fromthewesternAtlantic,withnotesonthetype
undescribed species (see Martin 1990). series ofD. ovata A. Milne Edwards, 1880.—
Itisinterestingtonotethatallofthespec- Journal ofCrustacean Biology 10:708-720.
imens I have herein referred to D. spinosa MilneEdwards,A. 1880. Etudespreliminairessurles
arefromoffFlorida. Thus, notonlyarethey Crustaces, 1"" partie. In Reports on the results
ofdredgingunderthesupervisionofAlexander
morphologically different from trueD. ova-
Agassiz, in the GulfofMexico, and in the Ca-
ta, but they are rather far removed geo- ribbean Sea, 1877, '78, '79, by the U.S. Coast
graphically as well, the holotype ofZ). ovata SurveySteamer"Blake,"Lieut.-CommanderC.
being from Barbados, and the MCZ 2745 D.Sigsbee,U.S.N.,andCommanderJ.R.Bart-
paratype being from Guadeloupe, Lesser lett, U.S.N., Commanding. Bulletinofthe Mu-
seum ofComparativeZoologyat HarvardCol-
Antilles. Thus, as far as is presently known,
lege 8(1):1-68.
D. spinosa is restricted to the Florida Keys, , & E.-L. Bouvier. 1902. Les Dromiaces et
while D. ovata, much rarer than was pre- Oxystomes. In Reportson theresultsofdredg-
VOLUME 107, NUMBER 3 457
ing,underthesupervisionofAlexanderAgassiz, Rathbun, M. J. 1937. The oxystomatous and allied
in the GulfofMexico (1877-78), in the Carib- crabsofAmerica.—UnitedStatesNationalMu-
beanSea(1878-79),andalongtheAtlanticcoast seum Bulletin 166:1-278.
ofthe United States (1880), by the U.S. Coast
Survey Steamer "Blake," Lieut.-Com. C. D. Natural History Museum ofLos Angeles
Sigsbee,U.S.N.,andCommanderJ.R.Bartlett, County,900ExpositionBoulevard,LosAn-
U.S.N., Commanding, 39.—Memoirs of the
Museum ofComparative Zoology at Harvard geles, California 90007, U.S.A.
College27(1):1-127.