Two new astroradiate echinoderms from the Pacific coast of Colombia and Ecuador

Vol. 30, pp. 171-174 October 23, 1917

PROCEEDINGS

OFTHE

BIOLOGICAL SOCIETY OF WASHINGTON

TWO NEW ASTRORADIATE ECHINODERMS FROM THE

PACIFIC COAST OF COLOMBIA, AND ECUADOR.

BY AUSTIN H. CLARK.*

On _{her voyage} from

the Atlantic to the

north

Pacificin

1887- 1888

the Albatross

dredged

^off

northwestern South America a magnificent new

starfish of the

genus

Luidia,

and

a

very

^inter- esting

new

species^of

the ophiuran genus

Ophiosteira,

which

are described

below.

Luidia superba,

new

species.

Sixarms;

R=205mm.

;

r=30mm.;

R:r=6.8:l; width^of

arms

_{at base,} 30

mm.

; superomarginalpaxillse, 100.

Arms

relatively stout, very gradually tapering ^to a blunt extremity^; interbrachial arcs very acute^; general form_depressed;

no

pedicellarise.

The

paxillse,though massive, areⁱⁿratheropen order,especiallyalong thesides ofthe_rays.

The

superomarginal paxillsecorrespond^to the inferomarginals

and

are closelycrowded _against

them;

ⁱⁿ shape they are approximatelysquare;

they bear centrally seven or eight prominent high rounded tubercles, surrounded by about^twiceas

many

^{similar but}

^more

^slender tubercles,

beyond

^whichare very

numerous

slenderspinelets.

Within

thissuperomarginal

row

isanother_regular

row

of similar, but smaller, paxillse, ^fiveofwhich correspond ^tofour superomarginals; ^these aremostly transverselyoblong,

becoming

squarishtoward the

end

ofthe ray; eachofthese_paxillseisentirelyindependent^ofthoseoneither side,

and

the seriesis separated fromthesuperomarginal ^series bya conspic- uouschannel.

Within

these again^isa third regular ^{series of} similar spaced paxilla?, corresponding exactly^to those in the second _row, from which _{they are} separated

by

^a

somewhat

broaderchannel thanthat separating thesecond

row

fromthesuperomarginals; every third or fourth^ofthese_paxillse(on

*Publishedwith the permission^ofthe SecretaryoftheSmithsonianInstitution.

42—Proc.Biol. Soc.Wash.,Vol.30, 1917. (171)

172

Proceedings ^ofthe Biological Society of

Washington.

the average) ^is

much

_enlarged

and

hears a stout conical centra] spine ahout3

mm.

_long.

The

next

row

isnotsoregularas those preceding,

and

iscomposed ^of slightlysmaller paxilhe, which are

more

rounded;

many

^of

^them

^hear

spines^likethoseinthe preceding row.

Withinthis fourth

row

the_paxillredecrease rapidly^{in size}and in reg- ularity, sothatthecentral thirdofthe

arm

isoccupied bysmall, irregular, closely placed, though ^notcrowded, roundedpaxillae,

many

^{ofwhich are}

enlarged

and

bear a conicalspine, especially inthe outer part^ofthearm.

On

the disk the paxillse in the _center, continuing thence along the midradial_region ofthearms,^aresmall

and

rounded; toward the inter- brachial arcs and the margins ^{of the}

arms

they rapidly

become

larger,

more

_oblong or quadrate,

more

_spaced,

and more

regular ⁱⁿ arrange- ment. Only one^ortwo^ofthe_paxillse on^{the disk}bear_spines, andthese spines are small^; onthe

arms

the spinesappear ^firstalong^thesides,

and

it isonly^{inthe outer half} that they

become

as

abundant

inthe

median

as inthelateral areas.

The

inferomarginal plates bear three long stout spines, ofwhichthe lowest, situated just belowthe ambitus, ^isthe_longest,9

mm.

inlength;

the second, situated at the ambitus, ^is similar, but_slightlyshorter; the third, situated on the abactinal surface, ^is the _shortest,usually about 4

mm.

long; ontheactinal surface belowthe ^first spine ⁱⁿ the preceding seriesthe inferomarginals bearfrom threeto five spines ^of considerable length, though

much

shorter than those in the upper^series, whichde- creasein sizetowardtheambulacral groove; the ^{sides of} the inferomar- ginalsarebordered with_very

numerous

capillary spinelets.

The

actinalintermediate_plateshave_{usually asingle}prominent

median

spine; ^theirproximal

and

distal bordersbear

numerous

_{capillaryspine-}

lets.

The

adambulacral_platesare _slightlynarrower than the actinal inter- mediate _plates,which inturn are_slightly narrower than ^the inferomar- ginals; they bear a sabre-shaped spine ⁱⁿ the furrow, followed by ^a similar, but_longer, stouter

and

lesscurved_spine, beyond which^are two slightly shorterstraight spines,thedistal the smaller; the inner half of the_plateisbare; theproximal

and

distalborders are fringed with

num-

erous capillary spines.

The mouth

platesarenarrow, witheleven gradually descreasing spines situatedalong^the

median

_suture,

and

four similar spines situated along the furrow margin^{; the}

mouth

_{spines proper}

may

^be said to consist of the firstspines ⁱⁿthese twoseries(theinner being thelarger)

and

a_third,

more

orless widelyspaced from ^these

and making

a considerable angle with them,^situated deep ^{in the}groove on ^{the aboral} edge^{of the} plate;

the border adjoining the ^first adambulacral is fringed with _capillary spinelets.

The

color in alcohol is a verydark

brown

_{above, the}crowns of the paxilk-ewhite except^forthe borderingspinelets, which are dark

brown

;

the enlarged spine-bearing paxillse

and

the abactinal surfaceoftheinfero- marginals^aredeep

brown

; the spines are white, except^forthoseincluded

Clark

—

Tivo

New

Astroradiate

Echinoderms. 173

inthetwo upper rows

on

theinferoniarginals, which have

brown

_bases;

beneath, straw yellow.

Type.—

^{Cat. No.} 36,948, U. S. N. M., from "Albatross" ^Station 2797, offthe coastofColombia,^{in 33}fathoms.

Ophiosteira ^koehleri,

new

species.

The

diskis5

mm.

indiameter; ^the

arms

_{are veryslender,} evenly tap- ering, 40

mm.

_long.

The

plates ofthe disk are few, large, greatly swollen; the ^radial areas are strongly elevated, the narrowlytriangularinterradial areas strongly depressed.

The

dorsal surface of the disk isoverlaidbya thin semi-transparent

membrane

with an approximatelyplane surfacewhichconceals theunder- lyingplates. In drying ^this

membrane may

cling tightly to the surface oftheplates,orit

may

stretch,

drum-head

like,betweenthe

more

elevated plates

more

or lessconcealing the othersfrom view.

The

radialshieldsare_large, rather narrow, greatlyswollen,extending fromthe baseof the

arms

half

way

^{to the centerofthe}disk, inapposition forthedistal half.

An

oval, greatly swollen, plate occupies the area between the inner halvesofadjacentradial shields; justwithinthisaretwoor three_similar, but

much

smaller, oval plates, radiallyelongated,

beyond

^{which is} the nearly^circularprimaryradial plate, which is of about the

same

area as the_platebetweentheinner halvesofthe radial shields ofeach _pair,

and

alsoastherounded-pentagonal^centralplate.

The

radial primaryplates are separatedfrom this last

by

a ring ^of small transversely oval plates,

and

from eachother, in their basal halves,bysimilar,butslightly larger, plates.

The

triangular interradial areas, embracing on^the borderof the disk the regionbetweenthe radialshieldsasa_base,

and

extending inward^to an apex between ^theprimaryradial plates,are occupiedby^alargekidney- shaped,

much

swollen, plate situated onthe border of the disk between the radial shields, in area about _equal to the_plate between the distal halvesof the radial shields of each_pair;

beyond

^{this on} either sideis a small hemispherical plate attachedimmediately below ^theradial shields, justwithin

which

is a transversely oval,

much

smaller,though similar, plate, bridging thegap between^theinnerendsofthe radial shields,

and

withinthisoneor

two

smallerplates.

Inlateral viewtheinterradialareasofthe disk are seen tobe occupied

by

^aboutsix irregularlyrounded swollen plates.

Along

^the genital ^slit there are about ten prominent^well separated conical papilla?, distal to

which

are

two

or three_larger,

more

robust,papilla?,forming^therudimen- tary

arm comb

whichisentirelyhiddenfromdorsalview by^theextension overitofthe produced^distalborderofthe radial shields.

The

oralshieldshave_{a broadly}heart-shaped inner portion, occupying about two-thirds of their radial length,

and

a smaller transversely oval outer portion, thetwo_{portionsseparated}by deep^{lateral notches.}

174

Proceedingsof the Biological Society of

Washington.

The

side

mouth

shields are about four times as long^asbroad, with parallel sides, in apposition inwardly.

The mouth

framesare similar_to,

and

not

much

larger than, the ^side

mouth

shields.

The mouth

papilte are^fiveinnumber,^thefirsttwo_{relativelylong,}

and

conical, the third of about the

same

basal length, but lower with a rounded outer border, the fourth ^of the

same

_height as the third but twice as long with a straight outer margin, ^{thefifth similar} but nearly threetimesas long^asthe_fourth, with a straight outermargin.

The

first

arm

tentacleliesinatube_consistingoffourroundedtentacle scalesinwardly,

and

three outwardly, thetwotentacleslits ineachinter- radialarea being parallel

and

not connected withthe

mouth

slits.

The

^first_upper

arm

plate^issmall, transversely oval,from twotothree times asbroadaslong; the second is

much

_{larger, reaching} almost en- tirely across the

arm

as viewed dorsally, twice as broad as long, the proximal

and

distal borders strongly curved and _parallel, the lateral edgesconvergingslightly;the followingupper

arm

_plates

become

_rapidly narrower, the^fifth beingan_elongatetriangle, twice aslong ^asthedistal width, the apex resting on the distal borderof the preceding;

beyond

the fifth theupper

arm

plates, becoming progressively smaller, are

more and more

widely separatedfrom eachother

by

the apposition ^ofthe side

arm

plates, on the outer portion ^of the

arm

being small

and

_inconspic- uous quadrilateralplates with the proximal angle

more

produced than the _distal, inserted between ^the distalinner bordersoftheapposed ^side

arm

_plates.

The arm

spines arethree, extremelyshort, well spaced, theuppermost slightlyfurtherfrom themiddle thanthelatteris from thelowest.

The

^first under

arm

_plate is triangular with very broadly rounded angles

and

a

somewhat

abrupt rounded^extensionoccupying^thecentral quarter ^of the distal edge; the second is slightly broader than _long, fan-shaped, with a truncatedproximal angle, with_{a strongly}

and

_evenly convex distal border

and

_strongly concavesides forming^{theinner bor-} ders of two broad _diverging slits which

accommodate

the _tentacles, protected bythree tentacle scales; the third is

more

broadlyfan-shaped than the preceding,

and

isexcluded from contact with it

by

the apposi- tion oftheside

arm

_{plates for}a distanceof half itslength; the following under

arm

_platesrapidly

become

smaller

and

_relativelybroader.

Type.—

^Cat.No. 38,670U. S. N. M., from "Albatross" ^Station2792, offthecoast of Ecuador, ^{in401 fathoms.}