Account Of Ophionereis Diabloensis, A New Species Of Brittle Star, And Of O-Amphilogus, With Information On Their Brooding Reproduction And Distribution (Echinodermata : Ophiuroidea : Ophionereididae)

18 Pages·2002·6.9 MB·English

by  G Hendler

PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON
115(l):57-74. 2002.
Account of Ophionereis diabloensis, a new species of brittle star, and
of O. amphilogus, with information on their brooding reproduction
and distribution (Echinodermata: Ophiuroidea: Ophionereididae)
Gordon Hendler
Natural History Museum of Los Angeles County, 900 Exposition Boulevard, Los Angeles,
California 90007, U.S.A.
—
Abstract. The present report on Ophionereis diabloensis, new species, and
Ophionereis (= Ophiodesmus) amphilogus, doubles the number ofOphionereis
species known from California waters and the number of brooding species
known in the genus Ophionereis. Ophionereis diabloensis reaches at least 6
mm mm
in disk diameter, with arms 17 in length. It is similar in appearance
to O. amphilogus but for its more irregularly arranged and exposed disk scales,
more robust arms and thick, truncate arm spines, larger accessory dorsal arm
plates, and distinctively shaped oral shields. The description of O. diabloensis
is based on material from Diablo Cove, California, the only locality where the
species is preserifly found. Evidence is presented, however, that individuals of
O. diabloensis, mistakenly identified as Ophionereis eurybrachiplax, formerly
occurred at Pacific Grove, California. Ophionereis amphilogus is reported from
the Baja California coast and from the California Channel Islands, extending
the known range of the species by approximately 800 km. Most specimens of
O. amphilogus, and many of O. diabloensis were brooding embryos. Individ-
uals of O. diabloensis contained up to 8 embryos, at different stages of de-
velopment and had no more than one embryo per bursa. The largest embryos,
mm
1.4 disk diameter, with approximately 15 arm joints, were similar in size
to the smallest free-living individuals collected in the field. Both species are
slow moving. Ophionereis diabloensis lives in algal turf in the intertidal zone,
and may be locally abundant, with a population density estimated at 20/m-.
Ophionereis amphilogus is found subtidally in kelp holdfasts. That two of the
four Californian species of Ophionereis have been overlooked and are so little
known, is illustrative of the general lack of study and of rigorous, systematic
surveys of Eastern Pacific echinoderms.
In 1996, while attempting to determine Tcbllected similar specimens at the site and
the geographic range of Amphiodia akos- acquired additional material from biologists
mos Hendler & Bundrick, 2001, I sought at the power plant. They represent an un-
access to the coastline adjacent to Diablo described species which, although distinc-
Canyon Power Plant, a nuclear generating tive, strongly resembles Ophiodesmus am-
station midway between Los Angeles and philogus Ziesenhenne, 1940.
San Francisco. Eventually I was permitted Prior to the present study, the only spec-
to examine specimens of several ophiuroids imens of O. amphilogus that had been re-
that had been collected fromthebufferzone ported were the three dredged in 1934, at
around the plant, and found among them a Cedros Island, offthe western coast ofBaja
small Ophionereis species that is a subject California, Mexico. Ziesenhenne (1940) as-
ofthe present report. In the following years, signed them to a new genus, Ophiodesmus,
58 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON
believing that they resembled both Ophi- roids are employed (Hendler et al. 1995).
onereis (Ophionereididae) and Ophiactis The diameter of the disk (dd), a standard
(Ophiactidae) species. He formed the name indicator of body size, was measured from
Ophiodesmus by combining the Greek for the outer edge of the radial shields to the
"serpent" (ophis) used in both generic opposite edge ofthe disk. The length ofthe
names with the Greek for "bond" {des- arm (AL) was measured for the longest arm
mos), intending to reflect a linkage between of an individual, from the edge of the disk
the two families, and chose the epithet am- to the arm tip.
philogus apropos of the "doubtful posi- Observations and measurements were
tion" of the species. However, he placed it made with a stereomicroscope, using a cal-
in the family Ophiochitonidae, to which ibrated ocular micrometer. Scanning elec-
Ophionereis was at that time assigned. tron microscopic (SEM) examination was
My initial impression that the specimens made using a Cambridge Stereoscan 360.
from Diablo Cove were of an Ophionereis Specimens were treated briefly with dilute
species was confirmed by A. M. Clark's sodium hypochlorite solution (bleach) tore-
(1953) review ofthe genus. She considered, move soft tissue, washed in water and eth-
but rejected, inclusion of O. amphilogus in anol, dried, sputter-coated with gold, and
a possible "subgenus Ophiodesmus'' with viewed at 10 KV.
several other ophionereidid species that re- Specimens were surveyed for evidence
tain seeminglyjuvenile features in the adult of embryos by examining their open bursal
growth stage. A. M. Clark (1953) disre- slits, without dissection. The estimated in-
garded Ophiodesmus degeneri A. H. Clark, cidence ofbrooding based on superficial in-
1949, the only other described species of spection is conservative, because in many
the genus, and A. M. Clark & Rowe (1971) cases the contents of the bursae were not
simply treated it as a species ofOphionereis visible. All specimens studied, except as
without reference to its original generic noted below, are deposited in the echino-
name. It seems clear that nominal Ophio- derm collection of the Natural History Mu-
desmus species lack features distinguishing seum of Los Angeles County (LACM).
them from Ophionereis species. Therefore, Individuals of the new species, O. dia-
A. M. Clark's decision to merge Ophiodes- bloensis, were collected in the vicinity of
mus with Ophionereis is adopted here. Diablo Cove, California (Fig. 1). Many
Consideration of the type specimens of specimens were obtained in the course of a
O. amphilogus coupled with study of indi- multi-year, algal-faunal association study,
viduals from the Channel Islands, con- and were extracted from 0.01 m-^ patches of
firmed that the species occurs in California Gastroclonium subarticulatum (Turner)
waters and is not restricted to the Mexican Kiitzing that were scraped from rock sub-
type locality. Furthermore, examination of strate exposed at low tide, then bagged in
individuals of O. amphilogus and the new the field and preserved in 70% ethanol
Ophionereis species described herein con- within several hours (J. Tupen, pers.
firm that both brood their young. Those comm.). Others were collected from Cen-
matters are covered below, along with a troceras clavulatum (C. A. Agardh) Mon-
consideration of the range of the species tagne and similarly preserved, and a few
and unpublished records that suggest that, specimens were extracted from a mixture of
at least in the past, the new species occurred various algae and anesthetized in isotonic
on the Monterey Peninsula. MgCL before preservation.
Individuals of O. amphilogus that were
Materials and Methods
collected in the vicinity of Catalina Island
In this publication, the customary meth- were removed from the holdfasts ofMacro-
odology and terminology used for ophiu- cystis pyrifera (Linnaeus) C. A. Agaidh,
VOLUME 115, NUMBER 1 59
and Eisenia arborea Areschoug. Using scu-
ba, the subtidal holdfasts were pried from
the substrate with hammer and crowbar af-
ter removing the stipe, and sealed in plastic
bags. Animals removed from the holdfasts
in the lab were preserved in 5% formalin
(Sherlock 1995). Individuals of O. amphil-
ogus from Santa Barbara and San Nicolas
islands were anesthetized and preserved in
ethanol, following removal from M. pyri-
fera holdfasts that had been collected sub-
tidally using scuba. Collecting data are
lacking for the single specimen from Bahia
Tortugas, Mexico, save that it was associ-
ated with an algal holdfast (Fig. 1).
Systematic Account Fig. 1. Chart of Baja California, Mexico and the
California coast showing the distribution ofOphioner-
Family Ophionereididae Ljungman, 1867 eis diabloensis n. sp. (circles) and Ophionereis am-
Genus Ophionereis Liitken, 1859 philogus (squares). Ophionereis diabloensis is found
intertidally at Diablo Cove, California (35°12.53'N,
120°51.36'W) and, early in the last century, probably
Ophionereis diabloensis, new species occurred in the intertidal at Pacific Grove, California
Figs. 2A-C, 3A-D, 4, 5A, B, 6A-C (36°37.7'N, 12r56.20'W). Ophionereis amphilogus is
— known from Cedros Island, Mexico (28°80.4'N,
[?] Ophionereis species. May, 1924, 299- 115°10.21'W, 18-27 m), Bahia Tortugas, Mexico
300, fig. 16. (27°41'N, 114°53'W, depth unknown), Santa Catalina
Ophionereis eurybrachiplax [not H. L. Island, California (33°28.0'N, 118°29.0'W, 5-10 m),
San Nicolas Island, California (33°15.736'N,
Clark, 1911].—Weesner, 1954: 290-291
119°27.719'W, 11.3 m), andSantaBarbaraIsland,Cal-
[in part?].—Sutton, 1975: 630, 633 [in ifornia (33°29.210'N, 119°01.657'W, 14.0 m).
part?].
—
Material examined. Unless otherwise 208.2, (2), Sta. AFAS 33654, 31 Jul 1992;
stated all specimens are preserved in alco- LACM 1993-176.1, (1), Sta. AFAS 33956,
hol, and were collected by J. Tupen and M. 7 May 1993; LACM 1993-178.1, (1), Sta.
Behrens at approximately to +1 ftMLLW AFAS 34053; LACM 1993-179.1, (1), Sta.
in the intertidal, on the southern shore of AFAS 34054; LACM 1993-180.1, (4), Sta.
Diablo Cove (35°12'32"N, 120°51'22"W), AFAS 34058, 18 Aug 1993; LACM 1993-
which is about 12 km NW of Point San 181.1, (1), Sta. AFAS 34155, 12 Nov 1993;
Luis, California. Series ofstations listedbe- LACM 1993-182.1, (2), Sta. AFAS 34157,
low are foll—owed by collecting date. 12 Nov 1993; LACM 1993-183.1, (4), Sta.
Holotype. Off Diablo Canyon., Califor- AFAS 34158; LACM 1993-184.1, (5), Sta.
nia: LACM 1999-29.20, (1 spec, dry). AFAS 34154, 12 Nov 1993; LACM 1994-
Coll: M. Behrens & R. Moran, 35°12'44"N, 146.1, (1), Sta. AFAS 34253; LACM 1994-
120°51'28"W,—5 Oct 1999. 147.1, (1), Sta. AFAS 34254, 10 Feb 1994;
Paratypes. Off Diablo Canyon., Cali- LACM 1994-148.1, (2), Sta. AFAS 34354,
fornia: LACM 1992-195.1, (1 spec), Sta. 27 May 1994; LACM 1994-149.1, (7), Sta.
AFAS 33752; LACM 1992-196.1, (3), Sta. AFAS 34251, 10 Feb 1994; LACM 1994-
AFAS 33753; LACM 1992-197.1, (3), Sta. 158.2, (1), Sta. AFAS 34553; LACM 1994-
AFAS 33755; LACM 1992-198.1, (1), Sta. 160.1, (1), Sta. AFAS 34551, 15 Nov 1994;
AFAS 33758, 12 Nov 1992; LACM 1992- LACM 1994-161.1, (1), Sta. AFAS 34557,
60 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON
15 Nov 1994; LACM 1995-166.1, (3), Sta. 1993-121.2, (2), Sta. RS 93-5, Coll: R.
AFAS 34651; LACM 1995-167.1, (1), Sta. Sherlock, Italian Gardens II, NW of Long
AFAS 34652, 25 Feb 1995; LACM 1995- Pt., 5-7 m, 19 Aug 1993. San Nicolas Is.,
168.1, (5), Sta. AFAS 34656, 25 Feb 1995; California: LACM 1999-88.1, (1), Sta. CI-
LACM 1995-169.1, (4), Sta. AFAS 34657, 99-4, Coll: G. Hendler et al., NE side of
LACM
25 Feb 1995; 1995-169.3, (1), Sta. island near navigational light, 11.2 m,
AFAS 34657, 25 Feb 1995; LACM 1995- 33°15.736'N, 119°27.719'W, 11 Sep 1999.
169.4, (1), Sta. AFAS 34657, 25 Feb 1995; Santa Barbara Is., California: LACM 1999-
LACM 1995-170.1, (6), Sta. AFAS 34658, 87.1, (1); LACM 1999-87.2 (1); Sta. CI-99-
LACM
25 Feb 1995; 1997-41.14, (3), Sta. 2, Coll: G. Hendler et al.. Arch Point, 14.0
GH site 1, Coll: G. Hendler et al., -1 ft m, 33°29.210'N, 119°01.657'W, 10 Sep
MLLW, 22 Jun 1997; LACM 1999-29.1, 1999.
LACM LACM —
(1); 1999-29.2, (4); 1999- Diagnosis. Small, brooding species
LACM LACM
29.3, (13); 1999-29.4, (1); with arm length:disk diameter ratio less
LACM
1999-29.5, (1); 1999-29.6, (1); than 4. Disk scale-covered, lacking primary
LACM LACM
1999-29.7, (11); 1999-29.8, rosette. Disk scales conspicuous, rounded,
LACM LACM
(5); 1999-29.9, (6); 1999- some completely exposed, others partially
LACM
L29A.1C1,M(3); 1999-29L.1A2,CM(1, dry), surrounded by small imbricating scales.
1999-29.14, (1); 1999- Large, exposed, dorsal interradial disk
LACM LACM
29.15, (1); L1A99C9M-29.16, (1); scales widerthan long, irregularly arranged;
L19A99C-M29.11979,9-2(91).;19, (1); Coll1:99M9.-2B9e.h18r,ens(1&); cmoemdipaalctesedr.iesRaodfiaslcaslheiselndesithsemralln;ardrioswtannocre
R. Moran, 35°12'44"N, 120°51'28'W, 5 Oct
1999; LACM 1993-177.1, (1), Sta. AFAS btheetiwreleenngtpha.irTehdresehiteoldfsousrliogrhatllypampiolrleaetahnadn
34013, Field's Cove, 35°12'56"N, 120°51'
30"WG,H18 Aug 1993; LACM 1997-42.10, (2), osanleatrenmtapcllaetesscalseubohnexeaagcohnaslid,eoovfejralwa.ppDionrg-.
CStoav.e, 3s5i°te122,'5C6ol"lN:,G.12He0n°d5l1e'r30e"tWa,l.. F-i1eld'fst Largest arm plates and spines on fourth to
MLLW, 22 Jun 1997. sixthjoint beyond disk edge, beyond which
arms taper considerably. One pair of con-
In addition, the following specimens of
spicuous accessory dorsal arm plates flank-
Ophionereis amphilogus:
Type material.—Cedros Is., Mexico: ing each dorsal arm plate on proximal
LACM three-quarters of arm; approximately one-
1934-161.014, holotype (1 spec,
dry), LACM 1934-161.013, paratype (2, sixth to one-fifth size ofdorsal arm plate on
dry). All types from RA^ Velero III, Sta. basal joints. Ventral arms plates subocta-
287-34, 28°4.80'N, 115°21.10'W, 18-27 m, gonal, with deep medial constriction, con-
10 Mar 1934. spicuously expanded distal lobe; width of
—
Non-type material. Bahia Tortugas, plate generally exceeding length, even at
Baja California, Mexico: SIO E1934, (1), midpoint of arm. Lateral arm plates con-
Stipe holdfast #33, ca. 27°41'N, 114°53'W, stricted proximally, with prominent, flaring
20 Nov 1959. Santa Catalina Is., California: spine ridge. Three thick, somewhat com-
LACM 1993-125.2, (2), Sta. RS 93-8, Coll: pressed arm spines, with truncate distaltips;
NW
R. Sherlock, Empire Landing, ofLong dorsal spines near disk longest, largest. Ten-
Pt., 5-7 m, 18 Aug 1993; LACM 1993- tacle scales single, large, ovoid, length
1 17.2, (1), Sta. RS 93-3, Coll: R. Sherlock, equaling one-half that of associated venti-al
Guano Rock, SE of Long Pt., 7-8 m, 3 Jul arm plate. In life, inegular, radial patches
1993; LACM 1993-116.2, (1), Sta. RS 93- or swirls of brown, greenish brown, pale
NW
5, Coll: R. Sherlock, Italian Gardens 11, green, and cream on disk; bands of similai^
of Long Pt., 6-10 m, 30 Jun 1993; LACM colors on arms; ventral interradii lack
VOLUME 115, NUMBER 1 61
patches of dark pigmentation immediately concave; radial corner rounded, lobate, par-
distal to oral sh—ield. tially overlapping first ventral arm plate.
Description. Disk diameter range 1.3- Ventral interradii covered with unequal
5.8 mm (holotype 5.1 mm); Arm length imbricating scales; medial scales largest,
range 2.5-16.9 mm (holotype 14.2 mm); those beside genital slit smaller, more close-
AL:dd ratio range 1.4-3.5 (holotype 2.8). ly crowded (Fig. 2C). Genital slit short,
Disk nearly circular, slightly inflated; arms equal in length to two arm segments. Rarely
gradually tapering beyond fourth joint. 1-2 granules (genital papillae) on genital
Disk covered by numerous, conspicuous, slit edge.
rounded, unequal imbricating scales (Figs. Arms considerably tapering, wider than
2B, 3A, 4). Larger scales separated to vary- high in cross section, dorsal and ventral sur-
ing degrees by irregularly arranged smaller faces somewhat convex; widest portion
scales; some large scales free of overlap- with longest arm spines and largest plates
ping scales. Large, exposed dorsal interra- includes fourth to sixth joints beyond edge
dial disk scales wider than long, irregularly of disk, terminal joints dorso-ventrally
arranged; medial series not crowded, com- compressed (Figs. 2, 5A, B). Arm plates
pacted. Rosette of primary plates lacking. granular due to shape of microscopic, pro-
Radial shields small, approximately truding, expanded peripheral trabeculae of
twice as long as wide; length approximately stereom; dorsal arm plates somewhat less
one-ninth of disk diameter; central area granulose than lateral and ventral plates.
Dorsal arm plates subhexagonal, with
slightly raised, ovoid in outline. Pairs of
shields separatedby slightly more thantheir medial section widest, distal edge convex
length, surroundedby scales ofvaried sizes. (Figs. 2B, 3C). First two plates smallerthan
Jaws protruding slightly beyond adoral succeeding plates, wider than long, with
convex distal margin. Basal plates slightly
shield. Three to four oral papillae on each
wider than long; distal plates subtriangular,
side ofjaw, close-set, somewhat dorso-ven-
with rounded distal edge, length equal to
trally compressed (Fig. 2C). Outermost pa-
width. Plates overlapping at base of arm,
pilla largest, broadest, flattest, with free
separated by lateral arm plates on outer
margin broadly rounded; inner three papil-
one-fifth of arm.
lae narrow, longer than broad, bluntly
Lateral arm plates wider than long, con-
pointed. Rarely, unpaired oral papilla at tip
stricted proximally, with prominent, pro-
of jaw. Tentacle scale of second oral ten-
truding spine ridge, (Figs. 2B, C, 3C, D).
tacle with bevelled apical edge; arising Arm spines three in number on each plate,
from adoral shield, distal to outermost oral
subequal, thick, broad, proximo-distally
papilla. Tentacle scale of first oral tentacle compressed, with truncate distal tip; upper-
set high on jaw in oral slit, rmudmimentary in most spine heaviest. Spines approximately
specimens approximately 2 dd, fully as long as basal arm segments, gradually
developed in most specimens ^3 mm dd. diminishing in relative length distally, ap-
Teeth four in number, broad, of equal proximately one-third the length of a seg-
length, wedge-shaped in sagittal section, ment near the arm tip.
apex convex or notched, surface of cutting Accessory dorsal arm plates conspicu-
edge composed of imperforate stereom. ous, subtriangular, approximately one-half
Oral shields quadrangular, approximately length and one-sixth to one-fifth size ofex-
as long as broad, inner edges longer than posed portion of dorsal arm plate on prox-
outer edges; inner apex of the shield trun- imal joints, diminishing in size toward tip
cate (Figs. 2C, 3B). Adoral shields trian- of arm (Figs. 2B, 3C). In small specimens,
gular, widest distally, narrowing proximal- only one basal arm joint bears accessory
ly, somewhat separated; radial edge slightly arm plates; in large specimens, up to 30
62 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON
Fig. 2. Ophionereis diabloensis. new species and Ophionereis ainphilogus. A-C, Ophionereis diabloensis.
5.1 mm dd, holotype, LACM 1999-29.20: A, entire specimen in dorsal view; B, detail ofdisk, dorsal view; C,
detail ofdisk, ventral view. D-F, Ophionereis ainphilogus, 4.4 mm dd, holotype, LACM 1934-161.14: D, entire
specimen in dorsal view; E, detail ofdisk, dorsal view; F, detail ofdisk, ventral view.
VOLUME 115, NUMBER 1 63
Fig. 3. Ophionereis diabloensis, new species and Ophionereis amphilogus. A—D, Ophionerels diabloensis,
5.23 mm dd, LACM 1999-29.19: A, Dorsal view ofa portion ofthe disk including two pairs ofradial shields,
showing the size and pattern ofthe scales; B, oral shield with truncate apex; C, fifth armjoint from the edge
of the disk in dorsal view showing the shapes of the dorsal arm plate, relatively large accessory dorsal arm
plate, and truncate arm spines D, fifth armjoint in ventral view showing the shape of the ventral arm plates.
E-H, Ophionereisamphilogus, 5.43 mmdd, LACM 1999-87.2: E, Dorsalviewofaportionofthediskincluding
two pairs ofradial shields, showing the size and pattern ofthe scales; F, oral shield with rounded apex; G, fifth
armjoint from the edge ofthe disk in dorsal view showing the shapes ofthe dorsal arm plate, small accessory
dorsal armplates, and arm spines withbluntly roundedtips; H, fifth armjoint in ventralview showing theshape
ofthe ventral arm plate. Scale: L 0.5 mm for A, E; J, 0.5 mm for B-D, F-H.
64 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON
joints (proximal three-quarters ofarm) bear brown bands incorporating small patches of
accessory plates. cream pigmentation. Disks oflarge individ-
Tentacle scales ovoid, longer than wide, uals predominantly brown and greenish
length one-half that of ventral arm plate, brown, irregularly marked with dark brown
seated in depression below tentacle pore, and cream, radiating pigmentation pattern
proximal end hinged to lateral arm plate indistinct; arms greenishbrown, withpatch-
(Fig. 3D). es of cream color and dark brown bands at
First ventral arm plate small, longer than intervals of several joints. Ventral surface
broad, distal margin convex, proximal end of all individuals predominantly cream col-
within oral slit. Plates at base of arm large, ored, with darkly pigmented arm joints
suboctagonal, longer than wide; proximal banded; largest individuals sometimes hav-
end narrow, lateral margins deeply concave, ing very small splotches ofbrown in ventral
distal margin conspicuously flared, with interradii. Large patches of dark pigmenta-
edge straight to broadly convex (Figs. 2C, tion typical of many Ophionereis species,
3D). Width of plate generally exceeds lacking distal to oral shields. Some arm
length at midpoint of arm. Plates pentago- spines ofmoderate- and large-sizedindivid-
nal on distal joints, triangular at tip of arm. uals banded with greenish or brown. In al-
Plates in contact basally, separated by side cohol greenish brown pigmentation turns to
arm plates on outer one-fifth of arm. green, green pigmentation fades; color loss
Terminal arm plate slightly longer than more dramatic in dried specimens, greens
wide, equally long and wide in some large and browns —fading to shades of gray.
individuals; base of plate inflated, apex Variation. The features of moderately
mm
bluntly rounded or truncate. large and large specimens (^3.5 dd) of
Tube feet in living individuals smooth, O. diabloensis are consistent (Table 1).
translucent, with long, somewhat expanded Smaller individuals, however, do not exhib-
tip. Individuals are slow moving; locomo- it the diagnostic oral shield shape, arm
tion involves use of tube feet in addition to spine shape, arrangement and shape of the
arm flexu—re. disk scales, and color pattern.
Color. Pigmentation and color pattern Notably, rare individuals have one ortwo
generally increase in intensity andcomplex- granules beside several genital slits, which
ity with increasing body size (Figs. 4, 5A, are presumably homologous with genital
B). In alcohol, small individuals, including papillae. Thus, the presence of genital pa-
large embryos, predominantly cream col- pillae is an inconsistent character for the
ored, with small dark brown patches on species. The variable degree with which
disk and widely-spaced brown bands on genital papillae are expressed in O. dia-
arms. Disk of small individuals predomi- bloensis confounds a clear-cut distinction
nantly cream colored with small, irregular, among Ophionereis species based on the
dark brown to greenish brown blotches, and presence or absence of genital papillae.
some intervening pale green pigmentation; However, the species falls in the group of
arms cream colored with widely-spaced species with "genital papillae absent" (sen-
brown and green bands. Disk of moderate- su A. M. Clark —1953).
sized individuals with large, irregular, in- Comparisons. The virtual absence of
terconnected, radiating patches and swirls genital papillae and the lack of an inteiTa-
of brown and greenish brown, discontinu- dial patch of dai'k pigmentation just distal
ously bordered with dark brown spots, and to the oral shield set O. diabloensis apait
with patches of pale green in intervening from two much larger Californian conge-
cream colored region; arms pale green, with ners, Ophionereis eurybrachiplax H. L.
narrow, dark brown band every few seg- Clark, 1911 and Ophionereis annidata (Le
ments, and with portions of green and Conte, 1851). Ophionereis eurybrachiplax
VOLUME NUMBER
115, 1
Fig. 4. Ophionereis diabloensis, new species. Detail ofthe disks offour specimens showing growth-related
changes in pigmentation pattern, and developmentofdiscontinuous darkbrownpigmentation separatingregions
of greenish-brown and cream coloration. A. 1.47 mm dd, LACM 1995-169.4; B, 2.07 mm dd, LACM 1995-
169.3; C, 4.08 mm dd, LACM 1999-029.18; D, 5.56 mm dd, 1999-029.16.
is further distinguished by having fourbasal adult growth stage. It includes O. sexradia
arm spines and dorsal arm plates that are at Mortensen, 1936, O. vivipara Mortensen,
least twice wider than long. Ophionereis 1933, O. olivacea H. L. Clark, 1901a, O.
annulata differs in the exaggerated length novaezelandiae Mortensen, 1936, and O.
ofits middle arm spine, and in its accessory dolabriformis John & A. M. Clark, 1954,
dorsal arm plates that are equal in length to which are distinguished from one another
the dorsal arm plates. in her key to the species of Ophionereis (A.
Ophionereis diabloensis and O. amphil- M. Clark 1953).
ogus fall into a small group of congeners The only species with which O. dia-
characterized by A. M. Clark (1953) as re- bloensis might be confused is O. amphilo-
taining seemingly juvenile features in the gus, and the differences between moderate-
66 PROCEEDINGS OFTHE BIOLOGICAL SOCIETY OF WASHINGTON
—
Table 1. Characteristics ofindividuals ofOphionereis diabloensis n. sp. and Ophionereis amphilogusequal
mm
or greater than 3.5 dd.
O-diabloensis O.amphilogus
Dorsal interradial disk Mid-interradial scales wider than long, ir- Mid-interradial scales longer than wide,
scales regularly arranged, not crowded. Some crowded into narrow columns. Few if
conspicuous scales completely exposed any scales completely exposed
Oral shield Truncate proximal tip Bluntly pointed proximal tip
Arm shape Arms robust, taper dramatically; largest Arms slender, gradually tapering from
dorsal arm plates and arm spines on disk, although first 2 dorsal arm plates
fourth to sixthjoint reduced in size
Accessory dorsal arm Approx. Vg-Vi size ofdorsal arm plate; Approx. '/|o size ofdorsal arm plate, not
plate on basaljoints overlapping and covering constriction at obscuring constriction at proximal end
proximal end ofarmjoint ofarmjoint
Ventral arm plates At mid-arm W > L; distal portion ofplateAt mid arm W < L; distal portion ofplate
appears much wider than proximal por- appears slightly wider than proximal
tion portion
Arm spine shape At base ofarm thick, robust; at midpoint At base ofarm compressed; at midpoint of
ofarm truncate arm bluntly rounded
Expanded peripheral Relatively large and evident at low magni-Relatively small and inconspicuous
trabeculae on dorsal fication
and lateral arm plates
Coloration Green and green-brown pigmentation Greenish pigmentation may be insignifi-
prominent; Arms greenish brown, irreg- cant; Arms brown or greenish, irregular-
ularly-banded with dark brown and ly-banded with dark brown and small,
small, irregularcream-colored spots; irregularcream-colored spots; Disk ir-
Disk greenish brown with cream-colored regularly variegated with brown and
patches separated or associated with dis- cream, sometimes predominantly cream-
continuous series ofdark brown scales colored
ly large and large individuals of the two from a "stipe holdfast" at Bahia Tortugas,
species are summarized in Table 1 and on the Baja California mainland, and col-
shown in Figs. 2, 3, and 5. Small individ- lected fromMacrocystispyrifera andEisen-
uals of the two species can be separated by ia arborea holdfasts at 4.6-14.0 m depth
the more robust development of the arms offSanta Cruz, San Nicolas, and Santa Bar-
and arm spines of O. diabloensis that is ev- bara islands in southern California.
ident in specimens compared side by side In contrast, Ophionereis diabloensis has
(Fig. 5). — been found associated with algal turf in the
Etymology. The specific name refers to intertidal zone. At Diablo Cove and envi-
the type locality of the species at Diablo rons O. diabloensis was collected intertid-
Cove, near the Diablo Canyon Nuclear ally, on a gradually-sloping rocky shelfdis-
Power Plant, Diablo Canyon, San Luis sected by fissures and tide pools, densely
Obispo County, California. covered with algae, masses of Phragmato-
poma californica (Fewkes, 1889), sponge,
Discussion
— and other sessile fauna. Echinoderms in the
Habitat. Ophionereis amphilogus oc- habitat included Asterina niiniata (Brandt,
curs subtidally and in association with large 1835), Henricia cf. leviiiscula (Stimpson,
kelp plants. Individuals have been dredged 1857), Leptasterias pusilla (Fisher, 1930),
from "from rock along the margins of a Pisaster ochraceus (Brandt, 1835), Pycno-
kelp bed" at 18-27 m depth, off Cedros podia helia?ithoides (Brandt, 1835), Lyte-
Island, Mexico (Fraser 1943:65, habitat il- chinus ananiesus H. L. Clark, 1912, Stron-
lustrated in pi. 32, figs. 70-71), removed gylocentrotiispiirpnratns (Stimpson, 1857),