Systematics of a Species Complex in the Deep-sea

Systematics of a Species Complex in the Deep-sea Genus Eurycope, with a Revision of Six Previously Described Species (Crustacea, Isopoda, Eurycopidae) by George D. F. Wilson

Systematics of a Species Complex in the Deep-sea Genus Eurycope, with a Revision of Six Previously Described Species (Crustacea, Isopoda, Eurycopidae) by George D. F. Wilson

UNIVERSITY OF CALIFORNIA PRESS Berkeley Los Angeles London

BULLETIN OF THE SCRIPPS INSTITUTION OF OCEANOGRAPHY OF THE UNIVERSITY OF CALIFORNIA LA JOLLA, CALIFORNIA Advisory Editors: Charles S. Cox, Edith S. Vincent, Abraham Fleminger, and Richard H. Rosenblatt (Chairman) Volume 25 Approved for Publication July 1982

UNIVERSITY OF CALIFORNIA PRESS BERKELEY AND LOS ANGELES CALIFORNIA

UNIVERSITY OF CALIFORNIA PRESS, LTD. LONDON. ENGLAND

ISBN: 0-520-09678-9 LIBRARY OF CONGRESS CATALOG CARD NUMBER: 83-5917

COPYRIGHT O 1982 BY THE REGENTS O F THE UNIVERSITY O F CALIFORNIA PRINTED IN THE UNITED STATES OF AMERICA

Library of Congress Cataloging in Publication Data Wilson, George D. F. Systematics of a species complex in the deep-sea genus Eurycope, with a revision of six previously described species (Crustacea, Isopoda, Eurycopidae) (Bulletin of the Scripps Institution of Oceanography, University of California, San Diego; v. 25) Bibliography: p. 1.Eurycope-Classification. 2. Crustacea-Classification. 3. Crustacea-North Atlantic Ocean-Classification. I. Title. 11. Series. QL444.M34W546 1983 595.3'72 83-5917 ISBN 0-520-09678-9

SYSTEMATICS OF A SPECIES COMPLEX IN THE DEEP-SEA GENUS EURYCOPE, WITH A REVISION OF SIX PREVIOUSLY DESCRIBED SPECIES (CRUSTACEA, ISOPODA, EURYCOPIDAE)

SYSTEMATICS OF A SPECIES COMPLEX IN THE DEEP-SEA GENUS EURYCOPE, WITH A REVISION OF SIX PREVIOUSLY DESCRIBED SPECIES (CRUSTACEA, ISOPODA, EURYCOPIDAE) BY GEORGE D. F. WILSON

ABSTRACT The genus Eurycope contains a taxonomically difficult species complex limited to the deep North Atlantic Ocean. The complex consists of 12 species, some of which have been hidden in the literature under the name of one of its members, Eurycope complanata Bonnier. This paper develops methods for identifying these species, 10 of which are new, and presents descriptions and a key. In addition, another closely related species group found only in the Norwegian and Arctic seas is redescribed and included in the key. The phylogenetic relationships of the complanata complex are explored and the results are displayed in a cladogram. The complex consists of two main groups with one intermediate species. Within one of the groups, there are two pairs of sibling species along with several species that have ambiguous relationships. Geographically co-occurring species pairs are examined. Each pair has mutually different morphologies of taxonomically important characters, size andlor mandibular shape, and it is suggested that resource partitioning between these pairs may occur.

ACKNOWLEDGMENTS Dr. Robert R. Hessler, SIO, has generously supplied facilities and access to his isopod collection, employment, and, most important, encouragement through the various stages of this research. His advice and suggestions were invaluable. Cecelia Ross, SIO, did the word processing; Dr. Richard H. Rosenblatt and Kittie Kuhns, SIO, made important editorial suggestions. The manuscript was clarified further by the careful attention of an anonymous reviewer. The individuals and institutions mentioned in the Materials section made this study possible by supplying specimens for research. Support was provided by National Science Foundation grants DEB77-24614 and DEB80-07150. I sincerely thank these people and institutions for their involvement in this paper. Special thanks go to my wife, M. Katherine Fries-Wilson, who helped me correct the manuscript proofs.

CONTENTS

ABSTRACT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Recognition of Species . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4 Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Institutional Abbreviations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 TAXONOMY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 The complanata complex . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Eurycope alia. new species . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Eurycope baea. new species . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Eurycope canariensis. new species . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Eurycope centobi. new species . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 Eurycope complanata Bonnier 1896 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 Eurycope diadela. new species . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 Eurycope grasslei. new species . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .27 Eurycope iphthima Wilson 1981 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31 Eurycope juvenalis. new species . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .33 Eurycope kurchatovi. new species . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 Eurycope propilosa. new species . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 Eurycope sandersi. new species . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .40 Relatives of the complanata complex. group C . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 Eurycope cryoabyssalis Just 1980. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 Eurycope inermis Hansen 1916. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .46 Eurycope hanseni Ohlin 1901 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .48 Eurycope ratmanovi Gurjanova 1946 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .51 KEY TO THE SPECIES OF THE COMPLANATA COMPLEX AND ITS RELATIVES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .53 PHYLOGENETIC RELATIONSHIPS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .57 CO-OCCURRING SPECIES PAIRS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .61 LITERATURE CITED . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63

INTRODUCTION A major problem in deep-sea systematics is the taxonomic recognition received by true biological species. Because sufficient samples are difficult to obtain from the deep sea, species from this realm are rarely characterized as well as their shallow-water counterparts. Knowledge of the autecology and behavior of deep-sea species is nearly nonexistent. Consequently, it is no surprise that some abyssal species are listed as cosmopolitan, despite their limited powers of dispersal or adult motility. Some of the megafaunal species may be resolved into biologically meaningful taxa using biochemical and genetic techniques, but only the morphological approach is currently feasible for the small, but numerically important, benthic macrofauna. In this paper a within-group comparative study has been applied to the taxonomy of the genus Eurycope, isopod crustaceans of the family Eurycopidae. Janiroidean asellotes, to which the Eurycopidae belong, are among the most abundant and speciose crustacean taxa in the deep sea (Hessler and Wilson, in press). Furthermore, this family is characteristic of the deep-sea faunas in the sense that it evolved in the abyss, rather than invading from shallow water after the family had differentiated from janiroidean ancestors (Hessler and Thistle 1975). Eurycopids have reevolved the ability to swim as evidenced by their paddle-shaped posterior legs and heavily muscularized, streamlined posterior body. Species and individuals of this family often dominate the isopod fraction of deep-sea samples; the increased ambit that swimming affords may be a factor in their apparent success. Of these abundant isopods, the largest genus, Eurycope, has proved to be especially useful in studies of speciation, biogeography, and taxonomy. Research into the taxonomic morphology of Eurycope (Wilson and Hessler 1980) has provided a suite of characters by which to identify species and genera (Wilson and Hessler 1981). This paper presents the results of an intensive study of one species flock within Eurycope, members of which often have been confused in the literature with the first described species, E. complanata Bonnier 1896 (see synonymies in Taxonomy section). In this paper the species flock is called the "complanata complex." The primary characters that separate the complanata complex from the rest of the genus are broad second pleopods with ventrally curved lateral fields and very broad uropodal protopods with distinct medial projections. RECOGNITION OF SPECIES The goal of this research was to construct a reproducible system by which species of the complanata complex could be identified. Ir. the initial survey of the Atlantic Eurycope, this complex seemed to be only a single species with a very broad range and puzzling combinations of variable characters. An intensive study of variation in one population (Eurycope iphthima Wilson 1981; in press) revealed a series of characters that could be applied to the separation of other populations as distinct species. The resulting taxonomy is based on three, often confluent, approaches. 1. Sexually dimorphic characters that may be associated with intraspecies recognition and morphological compatibility were chosen. In another janiroidean genus with species complexes, Jaera, the structure of the male copulatory organs is correlated with its function (Veuille 1978) and often can be used to distinguish closely related species or species groups (e.g., Veuille 1976, 1979). Male pleopods I and I1 of species in the complanata complex proved to be especially useful.

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Bulletin, Scripps Institution of Oceanography

2. Many utilized characters were stable on a population level and often in developmental sequences (Wilson and Hessler 1980; Wilson 1981). Abrupt disjunctions in character state between different localities helped identify different species. In several cases, distinct and invariant apomorphies (such as maxillary mediobasal denticles) were of great value. 3. Characters were also obtained from a study of co-occurring species in this complex, such as the E. sandersi-E. grasslei pair (see section on this subject). These species pairs had numerous character states with distinct bimodalities that unambiguously defined separate species. Such character states were applied profitably to comparisons between allopatric populations. The characters derived from these three approaches permitted the identification of 12 separate species in the complanata complex. The relationships between these species are further explored in the development of a cladogram (see Phylogenetic Relationships), and a key to the species is presented for practical identifications. METHODS Laboratory study used the methods of Wilson and Hessler (1980) and of Wilson (1981). Unless stated otherwise, limbs are illustrated as follows: uropods, pleopods, and mouthparts (except for the mandible) in ventral view; female pleopod I1 also in lateral view; antennulae and mandibles in dorsal view; and pereopods in lateral view. Arrows indicate enlargement of structures on limb illustrations. For clarity, setae are often omitted, but their insertions are indicated by circles or V-shaped marks on the natopods. Measurements were made from drawings or directly from camera lucida images using a stage micrometer for calibration. These measurements are extremely important for identifying the species. Characters are stated as ratios, such as endopod length 0.94 protopod width. If measurements were available from several specimens, a range is given, i.e., rostrum width 0.4-0.5 length. Unless means or medians are given, no statistical estimate is implied. However, care was taken to choose characters in which individual variation or the state of preservation would not interfere with accuracy. Meristic characters used in this work are subject to allometric and bilateral variation and are often stated as ranges. Body lengths for illustrated specimens are given in the figure captions to aid in the evaluation of allometries. Some measurements used in this paper require definition. 1. The FRONS HEIGHT is the distance from the base of the clypeus at the midline to the anterior tip of the rostrum. 2. The cephalic LATERAL SPINE LENGTH is measured from the tip of the spine to the angle between the dorsal margin of the spine and the cephalic anterior margin. 3. The MOUTHFIELD DEPTH is the distance perpendicular to the body axis from the posterior angle of the mandibular socket in the cephalon to the dorsal surface of the cephalon. These last three measurements of the cephalon are done in lateral view (see Fig. 9D). 4. The POSTROSTRAL CEPHALON LENGTH is measured in dorsal view from the most posterior extent of the antenna] sockets to the anterior edge of the first pereonite; the cephalic axis should be coincident with the pereonite's body axis. 5. The ROSTRAL WIDTH is measured perpendicular to the body axis at the most posterior extent of the rostra] indentation or notch.

Wilson: A Species Complex in Eurycope

5

6. The ROSTRAL OVERHANG is the distance the rostrum projects from the frons; operationally this measurement is usually done on intact specimens in dorsal view slightly rotated to the right or left in order to see the concavity below the rostrum (if present). 7. The ROSTRAL LENGTH is measured parallel to the body axis along a line from the rostrum's most anterior projection to a line connecting the most posterior extent of both antennal sockets. The rostra1 characters are generally obtained from a dorsal view, but the overhang may also be measured in lateral view on specimens that lack the proximal antennal and antennular articles. 8. The MEDIAL LOBE LENGTH of the antennular article 1 is the projected distance along the body axis from its distal tip to the insertion of article 2. 9. The mandibular CONDYLE LENGTH and the MOLAR PROCESS LENGTH are measured with the condyle in plan dorsal view; the latter measurement is the distance from the condyle's base to the denticles on the posterodorsal margin of the molar. 10. The MALE PLEOPOD I WIDTH is measured at the anterior edge of the dorsal orifice (generally seen in ventral view through the cuticle). 11. The female pleopod I1 KEEL LENGTH is measured in plan ventral or lateral view from the apex to the pleopod's proximal edge. 12. The male pleopod I1 VERMIFORM APPENDAGE length is the ventral distance from its distal tip to the posterior edge of the exopodal insertion. 13. The PLEOTELSON LENGTH is measured in lateral view from the anteriormost dorsal articulation of the pleotelson to its posterior tip. MATERIALS Specimens (Table 1, Fig. 1) came from a number of sources. Much of the collection derives from a deep benthic sampling program directed by Howard L. Sanders, J. Frederick Grassle, and Robert R. Hessler, based at the Woods Hole Oceanographic Institution. Other sources are: Expedition Intercalibration, a joint European study described in Sibuet (1979) (INCAL); Bay of Biscay and Canary Island samples collected by John A. Allen, Millport Marine Biological Laboratories, United Kingdom (Allen); Centre OcCanologique de Bretagne, France, programs in the Bay of Biscay and the Vema Fracture Zone (BIOGAS, POLYGAS, and BIOVEMA: Laubier and Sibuet 1970; Khripounoff et al. 1980). These latter samples were processed by the Centre National de Tri d'OcCanographie Biologique, directed by Michel Segonzac. Smaller collections were kindly provided by the following individuals: Torben Wolff, Zoological Museum of the University of Copenhagen loaned the Ingolf, Galathea, and Ak. Kurchatov specimens; John D. Gage, Dunstaffnage Marine Research Laboratory, United Kingdom, sent one isopod fraction from a time series study (Gage et al. 1980); Daniel Desbruykres, Centre OcCanologique de Bretagne, loaned specimens from BIOGAS I; J. Juget loaned the syntypes of Eurycope complanata retained at the UniversitC Claude Bernard, Lyon. The BIOVEMA specimens are currently in the possession of Robert Y. George, University of North Carolina at Wilmington. Holotypes are deposited at the United States National Museum of Natural History, or the Zoological Museum of the University of Copenhagen. The remainder of the specimens and paratypes are retained in the research collection of Robert R. Hessler, Scripps Institution of Oceanography.


TABLE 1. Localities of species in the Eurycope complanata complex. = co-occurs with another complex species; Symbols: * = type-locality; NC = not counted.

+

Program

*WHO1

+ WHO1

*WHO1

+ WHO1

*Allen Allen WHO1 *INCAL WHOI Allen BIOGAS I BIOGAS IX

*Caudan Galathea Allen *WHO1 WHOI

* + WHOI WHOI

+ WHOI + WHOI WHOI

+ WHOI + WHOI + WHOI +Ingolf +Ingolf

Station Number

299 293

Midpoint North Latitude

Midpoint West Longitude

Midpoint Depth

Eurycope alia, n. sp 07'55' 55'41 ' 54'04' 08'58'

Eurycope baea, n. sp 54'20' 295 08'04' 293 08'58' 54'04' Eurycope canariensis, n. sp 14'13' 6701 27'45 ' 6710 27'24' 15'40' 17'52' 142 10"301 Eurycope centobi, n. sp 1.3 57'59' 10"49' 313 51'31' 12'36' 44 43'40' 03'34' 08'40' DS13 47'34' 09'06' KG169 47'32' Eurycope complanata Bonnier 1896 13 44'17' 04'38' 77 1 47'48' 08'26' 40 43'36' 03'25 ' Eurycope diadela, n. sp 340 38'16' 70"22' 126 39'35' 66'45 ' Eurycope grasslei, n. sp 66 38'46' 70"08' G3 39"401 70'37' 62 39'25' 70'33' 64 38'46' 70'37' 65 38'28' 70'07' 72 38'16' 7 1'46' 39O37' 67'58' 76 131 36'28' 67'58' 24 63'06' 56'00' 36 61'50' 56'21'

(m)

2009 1487 1011 1487 1934 2670 1710

Number of Individuals


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TABLE 1. (continued) Localities of species in the Eurycope complanata complex. Symbols: * = type-locality; + = co-occurs with another complex species; NC = not counted.

Program

Station Number

Midpoint North Latitude

Midpoint West Longitude

Midpoint Depth (m)

Number of Individuals

Eurycope iphthima Wilson, 1981 (new and co-occurrence localities) 13'16' 54'52' WHOI 37'58' 69"25' WHOI 38'33' 68'3 1' + Gage 54'36' 12'17' INCAL 12'36' 55'0 1' POLYGAS 43'33' 09'37' POLYGAS 47'32' 09'41 ' POLYGAS 44"24' 04'48 ' Ak. Kurchatov 14'42' 66'45' Eurycope juvenalis, n. sp *WHO1 156 00"46'(S) 29'25 ' WHOI Oo"O2'(S) 27'47 ' 155 WHOI 10'30' 18'18' 149 + WHOI 13'16' 54'52' 287 BIOVEMA 10"47' 42'4 1' DS03 BIOVEMA 10"47' 42'4 1' DS04 BIOVEMA 10"46' 42'40' DS05 BIOVEMA DSll 11'38' 32'53 ' Eurycope kurchatovi, n. sp *Ak. Kurchatov 1194 19'38' 68'09'

+ WHOI +

Ak. Kurchatov *WHO1 WHO1 WHO1

* + WHOI

+ WHOI + WHOI WHOI + WHOI

+ WHOI WHOI +Ingolf Ingolf + Gage + INCAL

118 1 303 30 1 306

19'54' 68'14' Eurycope propilosa, n. sp 08'28' 56'04' 08'12' 55'49' 56"201 09'3 1' Eurycope sandersi, n. sp 36'28' 67'58' 39'25' 70'33' 38'46' 70'37' 38'46' 70'08' 38'16' 71'46' 39'37' 67'58' 39'43' 70'37' 56"001 63'06' 61'50' 56"21f 54'36' 12'17' 55'01' 12'36'


Figure 1. Localities for the complanata species complex in the North Atlantic Ocean. Open circles define areas that may enclose one or several sample positions. Species are abbreviated on the map as follows: G , E. grasslei, n. sp. A, Eurycope alia, n. sp. I, E. iphthima Wilson B, E. baea, n. sp. C, E. complanata Bonnier J , E. juvenalis, n. sp. K , E. kurchatovi, n. sp. Ca, E. canariensis, n. sp. Cn, E. centobi, n. sp. P, E. propilosa, n. sp. S, E. sandersi, n. sp. D, E. diadela, n. sp.

INSTITUTIONAL ABBREVIATIONS AMNH: American Museum of Natural History, New York, USA. CENTOB : National Sorting Center for Biological Oceanography, Brest, FRANCE RRH: Personal collection of Dr. Robert R. Hessler, Scripps Institution of Oceanography, La Jolla, California, USA. UCBZM: Zoological Museum of the University of Claude Bernard, Lyon, FRANCE USNM: National Museum of Natural History, Smithsonian Institution, Washington, D.C., USA WHOI: Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, USA ZMMU: Zoological Museum of Moscow University, USSR ZMUC: Zoological Museum of the University of Copenhagen, DENMARK

TAXONOMY THE EURYCOPE COMPLANATA COMPLEX Family Eurycopidae Hansen 1916 Subfamily Eurycopinae Hansen 1916 Genus Eurycope Sars 1864 Diagnosis (modified from Wilson and Hessler 1981). Eurycopidae with deep, vaulted and rounded natasome; venter with no enlarged or recessed areas; body without dorsal or lateral spines. Tergal articulations of pereonites 5-7 distinct; pereonite 7 subequal to or longer than pereonites 5 and 6. Rostrum and frons distinct; clypeus narrow, striplike; labrum longer than clypeus. Pleotelson posterolateral margin parallel to pleotelson longitudinal axis or angled downward in lateral view. Antennular first article broad, with well-developed medial lobe. Mandibular molar triturating surface broad, oval, with tiny denticles and small setae on posterior edge; ventral edge flattened into angular blade. Mandibular palp well developed and functional; flattened distal article strongly curled laterally. Bases of perepods I-IV subequal to body depth. Bases of pereopods V-VII subequal, short, and robust. Uropods short, biramous; protopod broad or tubular, not leaflike; exopod subequal to or shorter than endopod. Species of the complanata complex may be recognized by the following characters. Rostrum (Fig. 9G, H ) short and narrow with distinct anterior notch and only tiny simple setae; cephalic keels small or absent, without denticles. Cephalon with pointed lateral spine; frons height less than half mouthfield depth (Fig. 9D). Ventral surface of natatory pereonite 7 with distinct bullae (see Wilson and Hessler 1980, Fig. 4C). Pleotelson tip with distinct downward angle. Mandibular palp shorter than body of mandible. Maxillipedal epipod with subquadrate lateral projection. Pleopod I1 of both sexes with enlarged and anteriorly recurved lateral fields fringed by hemiplumose setae (e.g., Fig. 15G, H ) . Pleopod I1 of female posteriorly rounded, apex near distal tip. Pleopod I1 of male with vermiform appendage (see Wilson 1981, Fig. 10K). Uropodal protopod broader than long with acute medial projection.

Eurycope alia, new species (Figures 2-3) Holotype. Early preparatory female, body length 4.8 mm, USNM 183769, from WHO1 299, 7"55'N, 55"41rW, 2009 m. Paratypes. Seventy-six individuals, most fragmentary, RRH. General Distribution. Bathyal slopes off Guiana, South America, 1487-2009 m, see Table 1. Derivation of Name. Alia is a Latin adjective meaning "another," the author's reaction to distinguishing yet another species of the E. complanata complex. Diagnosis: Adult body length ca. 4.8 mm, length 2.3 width, pleotelson almost as long as wide. Rostrum (Fig. 2E, G-H) somewhat broad, with U-shaped notch and little or no overhang; width 0.46 length, length 0.25 cephalon width. Antennular article 1 medial lobe with 5-7 setae, longest seta 0.8 medial lobe length; article 2 subequal to or slightly shorter than medial lobe (length ratio 0.9-1.0); third article shorter than second article in

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males and longer than second article in females (length ratios 0.63 and 1.1). Maxillary mediobasal region with 3-4 tiny scalelike denticles. Male pleopod I distal tip inner lobe broadly rounded in ventral view, with narrow lateral shelf that extends medially along posterior margin; outer lobe thin, curved, spinelike, separate but close to inner lobe, length nearly as long as inner lobe. Male pleopod I1 vermiform appendage thin, distally truncate, moderately long with no terminal setae, length 0.09 protopod length; stylet with penultimate medial lobe on sperm duct at termination of cuticular sheath. Uropodal endopod length subequal to protopod width; exopod longer than half endopod length.

Figure 2. Eurycope alia, n. sp. A-F, holotype early preparatory female, 4.8 mm. G-H, paratype brooding female fragment. I, male fragment. J-L, paratype early preparatory female, 4.4 mm. A-B, lateral and dorsal views. C, lateral margins of pereonites 1-4. D, anterior cephalon, lateral view. E, left antennula and rostrum, dorsal oblique view. F, pleotelson, ventral view. G, cephalon, frontal oblique view. H, lateral view of rostrum, frons, lateral spine and labrum, cuticular ridges on labrum enlarged. I, male right antennula. J, left mandible. K, incisor process and lacinia mobilis. L, maxillary mediobasal region.


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Description. Body characters (Fig. 2): body with fine scattered setae only on lateral margins. Cephalic frons height 0.32 mouthfield depth; lateral spine length 0.64 frons height. Pleotelson length 0.95 width, length 0.33 body length. Antennula (Fig. 2E, I): In female, length 0.30 body length; flagellum length 0.52 total length, with 15 annuli. In male, flagellum length 0.73 total antennular length, with 52 annuli. Left mandible (Fig. U - K ) :Molar process subequal to condyle length, with 6 setae on distal posterior edge; anterior edge not enlarged or rounded. Spine row with 7 members. Lacinia mobilis with 9 denticles, 3 tiny ones on dorsal edge. Palp second article length 0.48 mandibular body length. Maxilliped: Basis with 5 receptaculi medially and 6 stout and 8 simple setae on ventral surface; distinct lateral gap in row of 5 fan setae on distal tip. Epipod length 1.8 width, length slightly longer than basis; ventral ridge with 3 stout and 2 simple setae. Pleopod I of male (Fig. 3B-C):Sympod length 3.6 width, with 6-7 setae on each side. Inner lobe length 0.48 distance between bases of outer lobes. Pleopod I1 of male (Fig. 3 0 ) : Protopod length 1.3 width, with 9 hemiplumose setae on lateral margin. Stylet of endopod length 0.81 protopod length. Pleopod I1 of female (Fig. 2F): Length 0.73 width. Lateral margin with 9 hemiplumose setae. Posterior margin in lateral view rounded adjacent to apex, perpendicular to keel more dorsally. Uropod (Fig. 3A): Endopod length 0.98-1.02 protopod width, length 0.28-0.29 width. Exopod length 0.64-0.68 endopod length. Protopodal setal row with 19 members.

Figure 3. Eurycope alia, n. sp. A, paratype early preparatory female, 4.4 mm, uropod. B-E, paratype copulatory male, 4.3 mm, pleopods 1-111; C, enlargement of pleopod I distal tip.

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Remarks. Eurycope alia has confused relationships with two different groups of species because of two conflicting synapomorphies. The maxillae of the species E. iphthima and E. grasslei have 6-7 large denticles on the mediobasal region at the insertions of long thin setae; smaller and fewer maxillary denticles are found in E. alia, perhaps signifying an intermediate condition between the above species pair and those species that lack this special morphology. The second synapomorphy, shared only with E. sandersi, is a distal bulbous thickening on the sperm duct of the male pleopod I1 stylet. Eurycope alia is similar to E. iphthima and E. grasslei in rostra1 and antennular morphology, but unlike all the above species, it has a mandibular molar process that is subequal to the condyle, and a short and thin vermiform process of the male pleopod 11. Females of E. alia may be identified by the form of the maxillary mediobasal denticles, the mandibles, and the pleotelson length-width ratio. Eurycope baea, new species (Figures 4-5) Holotype. Copulatory male, body length 3.0 mm, USNM 183779, from WHO1 295, 8"04'N, 54"20fW, 1011 m. Paratypes. Brooding female, body length 2.8 mm, ZMUC; juvenile male, body length 2.2 mm, ZMUC. General Distribution. Bathyal slopes of the Guiana Basin, off northern South America, 1011-1487 m, see Table 1. Derivation of name. Baea is a Greek adjective meaning "small," referring to the size of this species compared to the co-occurring Eurycope alia. Diagnosis. Adult body length 2.7-3.2 mm, length 2.3 width. Rostrum (Fig. 4E-F) long, indented, with no overhang; length 0.27-0.30 cephalon width; rostrum broader in females than males, width ratios 0.60-0.61 and 0.41-0.49. Antennular article 1 medial lobe with 4-5 unequally bifid setae, longest seta slightly longer than medial lobe; article 2 in females subequal to, and in males shorter than, medial lobe (length ratio 0.9-1.0); third article subequal to or slightly longer than second article (length ratios 1.0 in males, 1.1 in females). Male pleopod I distal tip inner lobe subtriangular and distally rounded in ventral outline with no lateral shelf. Outer lobe separate from thin inner lobe; outer lobe recurved and spinelike, slightly shorter than inner lobe length. Male pleopod I1 vermiform appendage short and thick with no terminal setae, length 0.05 protopod length; endopodal stylet distal to exopod very thin, diameter primarily sperm duct width. Uropodal endopod slightly longer than protopod width; exopod longer than half endopod length. Description. Body characters (Fig. 4): Body with few simple setae on dorsal surface, mostly on lateral margins. Frons of cephalon with distinct frontal ridges continuous with lateral keels of rostrum; frons height 0.28 mouthfield depth; lateral spine length 0.94 frons height. Pleotelson length 0.86 width; length 0.32 body length. Antennula (Fig. 4G-I): In male, length only 0.3 body length; flagellum length 0.46 antennular length, with only 11-12 annuli. Left mandible (Fig. 4J-N): Molar distinctly longer than condyle; posterior margin of distal surface with 6 setae; anterior margin not enlarged, rounded, nor heavily cuticularized. Spine row with 7 members. Lacinia mobilis with 8 denticles, 2 small denticles on dorsal margin. Palp second article 0.47 mandibular body length. Maxilla (Fig. 40): Mediobasal area with no denticles nor short curved setae.


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Figure 4. Eurycope baea, n. sp. A-B, holotype male, 2.9 mm. All remaining illustrations are of paratypes. C-D, brooding female, 2.7 mm. E, late preparatory female, fragment, F,I, juvenile male, 2.2 mm. G , copulatory male, 3.2 mm. H, J-Q, brooding female, 3.2 mm. A-B, lateral and dorsal views. C, lateral view. D, lateral margins of pereonites 1-4. E, lateral view of rostrum, frons, lateral spine and labrum. F, rostrum, dorsal and oblique views. G , male antennula. H, female antennula. I, juvenile male antennula. J-N, left mandible; K, molar process, medial view; L, molar process and condyle, posterior view; M, lacinia mobilis and incisor process; N, spine row. 0, maxillary mediobasal region. P, maxilliped. Q, uropod.

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Maxilliped (Fig. 4P): Basis with 4-5 receptaculi and 4 unequally bifid and ca. 14 simple setae on ventral surface; distal row of 5 fan setae with distinct lateral gap. Epipod length 1.8 width, length subequal to basis, ca. 5 simple setae on ventral ridge. Pleopod I of male (Fig. 5A): Sympod length 3.0 width, with 3 hemiplumose setae on each side; inner lobe length 0.38 distance between bases of outer lobes. Pleopod I1 of male (Fig. 5B): Protopod with 6 hemiplumose setae on lateral margin. Stylet of endopod length 0.87 protopod length, section distal to exopod abruptly very thin, with sperm duct protruding from almost negligible cuticular sheath. Pleopod I1 of female (Fig. 5C-D): Length 0.77 width; depth 0.17 length; keel length 0.95 total length of pleopod. Lateral margins with 5 setae. Keel narrow, apex set close to distal tip; posterior margin in lateral view almost perpendicular to keel. Uropod (Fig. 4Q): Endopod length 1.0-1.1 protopod width; width 0.32 length. Exopod length 0.61-0.66 endopod length. Protopod setal row with 16 members. Remarks. Eurycope baea is unique within the complanata complex because of several characters that occur in no other species. The distal tip of the male pleopod I and the thin stylet of pleopod I1 are the most distinctive, but the long, broad rostrum and the very short adult antennulae, which have very long medial lobe setae, also contribute to the uniqueness of E. baea. This species is morphologically isolated from all the other species in the complex.

Figure 5. Eurycope baea, n. sp. A-B, paratype copulatory male, 3.0 mm, pleopods 1-11. C-G, paratype brooding female, 2.7 mm; C-D, pleopod 11; E-G, pleopods 111-V.

Wilson: A Species Complex in Eurycope Eurycope canariensis new species (Figure 6) Holotype. Early preparatory female, 3.7 mm in length, uropods and distal parts of antennae and pereopods missing, USNM 183778, from off the Canary Islands, Allen station 6701, 27"45'N, 14"13'W, 1934 m. Paratypes. Two juvenile males, RRH. General Distribution. Off the northwestern coast of Africa, 1710-2670 m, see Table 1. Derivation of Name. This species is named canariensis because the type-locality is near the Canary Islands. Diagnosis. Adults 3.3-3.7 mm long, instar 4 length 1.8 mm; length 2.0 width. Rostrum short and moderately broad, with distinct rounded notch, and some overhang; length, notch, and overhang greater in males; length 0.18 cephalon width, width 0.5 length. Antennular article 1 medial lobe with 8 unequally bifid setae, longest seta 0.7 medial lobe length; article 2 shorter than medial lobe, length ratio 0.9; third article longer than second article, length ratio 1.1. Male pleopod I distal tip inner lobe bilobed in ventral view with subterminal lateral projection in addition to thick medial part; outer lobe ventrally curved, thin, and pointed, approximately as long as inner lobe. Male pleopod I1 vermiform appendage short and thick, length 0.10 protopod length. Uropodal endopod length subequal to protopod width; exopod longer than half endopod length. Description. Body characters (Fig. 6): Dorsal surface devoid of setae except for few simple and stout setae on lateral margins; cephalic anterior margin with 2 setae adjacent to lateral spine. Frons height 0.32 mouthfield depth; lateral spine 0.95 frons height. Rostrum varies from no overhang and shallow notch in female to moderate overhang and notch in male (overhang 0.18 rostral length). Pleon length 0.84 width, length 0.33 body width. Left mandible (Fig. 6H-J): Condyle longer than molar (length ratio 1.2); molar with 6 setae. Spine row with 6 members. Lacinia mobilis with 7 denticles. Palp second article 0.47 mandibular body length. Maxilla: Mediobasal area with no small recurved setae or denticles at bases of long, thin setae. Maxilliped: (Fig. 6G): Basis with 5 receptaculi medially, ventral surface with 5 stout unequally bifid setae and approximately 4 thin simple setae, distal row of 5 fan setae with distinct lateral gap. Epipod length 1.7 width, length subequal to basis; 3 stout setae on ventral ridge. Pereopods I-IV: Basis length-body length ratios 0.24, 0.23, 0.23, 0.24. Pleopod I of male (Fig. 6K-L): Sympod length 3.4 width, with 4-7 hemiplumose setae of ventral surface. Inner lobe length 0.47 distance between bases of outer lobes. Pleopod I1 of male (Fig. 6M): Protopod length 1.5 width, with 10 unequally bifid setae on lateral margin. Stylet of endopod 0.85 protopod length; sperm duct projects from thin cuticular sheath, tip rounded. Uropod (Fig. 6N): Endopod length 0.97 protopod width, width 0.31 length. Exopod length 0.64 endopod length. Protopodal setal row of juvenile male (body 2.9 mm long) with 16 members. Remarks. Of the small species (adult lengths in the 3-4 mm range), Eurycope canariensis is most similar to E. centobi, particularly in rostral and antennular characters. E. cana-

16

Bulletin, Scripps Institution o f Oceanography

Figure 6. Eurycope canariensis, n. sp. A-C, holotype early preparatory female, 3.7 mm. D-E, K-M, copulatory male, 3.3 mm, WHOI 142. F, head fragment, WHOI 142. G-J, N, paratype juvenile male, 2.9 mm. A, dorsal view. B, antennulae, rostrum, and frons, dorsal oblique view. C, lateral margins of pereonites 1-4. D, male antennula. E, male rostrum, dorsal view. F, rostrum, frons, lateral spine, and labrum in lateral view. G , left maxilliped. H-J, mandible; I, incisor process and lacinia mobilis; J, molar process and condyle. K-L, male pleopod I with enlargement of distal tip. M, male pleopod 11; N, left uropod.


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riensis may be recognized by the following characters: the body and pleotelson are narrower, pleopod I of the male has a distinctly bilobed inner lobe, and the endopod of the uropod is subequal to the protopodal width. Other characters include more hemiplumose setae on pleopods I and 11, and fewer receptaculi and simple setae on the basis of the maxilliped. The other small species (E. sandersi, E. baea) that also have thick vermiform appendages may easily be separated using antennular, rostral, uropodal, and male pleopod I characters. Eurycope centobi new species (Figures 7-8) Eurycope complanata (not of Bonnier 1896): Chardy 1975, p. 9, in part; Chardy 1979, p. 81, in part; Desbruy6res et al. 1980, p. 228. Holotype. Early preparatory female, 3.0 mm long, USNM 183777, from INCAL station 1.3, 57"59'N, 10"49'W, 2081 m, off the northwestern British Isles. Paratypes. Sixteen individuals, all immature or fragmented, RRH. General Distribution. Off northern British Isles, southwestern Ireland and in the Bay of Biscay, 1495-2815 m, see Table 1. Derivation of Name: In honor of the French Centre National de Tri d'ockanographie Biologique (CENTOB). Diagnosis. Adult body length 3.0-4.2 mm, instar 4 length 1.9 mm, length 1.9-2.0 width. Rostrum short and moderately broad, rostral notch U-shaped; width 0.57-0.64 length, overhang 0.13-0.16 length, length 0.19-0.21 cephalon width. Antennular article 1 medial lobe with 8 unequally bifid setae, longest seta 0.8 medial lobe length; article 2 shorter than medial lobe (length ratio 0.9); third article slightly longer than second article (length ratio 1.1). Male pleopod I distal tip inner lobe rounded with lateral shelf; outer lobe thin, ventrally curved, spinelike, longer than inner lobe. Male pleopod I1 vermiform appendage short and thick, length 0.08 protopod length. Uropodal endopod longer than protopod width; exopod longer than half endopod length. Description. Body characters (Fig. 7): Dorsal surface with few fine setae on pleon and lateral margins; three stout setae on cephalon anterior margin adjacent to lateral spine. Frons height 0.36 mouthfield depth; lateral spine 0.93 frons height. Pleotelson length 0.79 width, length 0.33 body length; in lateral view posterior margin with only slight downward angle. Antennula (Fig. 7H-I): In female, approximately 0.4 body length, with 15 flagellar annuli beyond article 4; flagellar length 0.54 total antenna1 length. Mandible (Fig. 7K-M): Condyle longer than molar process (length ratio 1.2). Molar process with 6 setae, anterior distal edge thickened and rounded. Spine row with 8 members. Lacinia mobilis with 6 denticles. Palp second article length 0.45 mandibular body length. Maxilla: Simple mediobasal area, no denticles or recurved setae. Maxilliped (Fig. 7 4 : Basis with 6 receptaculi medially, 5 stout and approximately 14 simple setae ventrally; distal row of 5 fan setae with distinct lateral gap. Epipod length 1.8 width, length subequal to basis length, 3 stout setae on ventral ridge. Pereopods I-IV (Fig. 7 0 ) : Basis-body length ratios 0.23, 0.23, 0.23, 0.24.

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Figure 7. Eurycope centobi, n. sp. A-D, holotype early preparatory female, 3.0 mm. E, juvenile female, 2.6 mm, WHO1 313. F-N, paratype brooding female fragment, estimated length 3.6 mm. A-B, lateral and dorsal view. C, lateral margins of pereonites 1-4. D, pereopods I-IV, bases and coxae. E, dorsal view. F, cephalon, left antennula and antenna removed, frontal oblique view. G, lateral view of rostrum, frons, lateral spine, and labrum. H, right antennula. I, left antennula, medial view of medial lobe. J, left maxilliped. K-M, left mandible; L, molar process and condyle; M, incisor process and lacinia mobilis, anterior view, new process shown beneath cuticle, indicating amount of wear between molts.


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Pleopod I of male (Fig. 8A-B; parenthetical values are for juvenile male): Sympod length 3.2 (3.3) width, with 3-4 (2) pairs of hemiplumose setae. Inner lobe length 0.33 (0.35) distance between bases of outer lobes. Pleopod I1 of male (Fig. 8A-B; parenthetical values are for juvenile male): Protopod length 1.6 (1.7) width, with 4 (3) hemiplumose setae on lateral margin. Stylet of endopod length 0.83 (0.87) protopod length; sperm duct distally thickened but not bulbous. Pleopod I1 of female (Fig. 8C): Length 0.88 width, depth 0.26 length; lateral margin with 6 hemiplumose setae. Distal tip somewhat bulbous, sloping and rounded posterior to apex in lateral view. Uropod (Fig. 8D): Endopod length 1.1 protopod width, width 0.24 length. Exopod length 0.67 endopod length. Protopod with 18 long unequally bifid setae in row. Remarks. Eurycope centobi is most similar to E. canariensis, especially in the rostra1 and antennular characters. Eurycope centobi may be recognized by a broad body and pleotelson, rounded inner lobe of the male pleopod (not bilobed), and an uropodal endopod that is longer than the protopodal width. Some differences were found between specimens from off the northwestern and southwestern British Isles. Compared to the INCAL station 1.3 specimens, those from WHOI 313 are broader, less deep, less extended in the ambulatory pereonites and have better defined curves in the pleotelson. However, these latter specimens also have a whiter preservation color and seem to be more calcified. Because other diagnostic characters are identical, the differences in the two populations are probably due to postsampling pres-

Figure 8. Eurycope centobi, n. sp. A, paratype juvenile male, 2.2 mm (instar 5 ) , male pleopods I-II. B , copulatory male, 2.8 mm, WHOI 313, male pleopods I-II. C, paratype brooding female fragment, estimated length 3.3 mm, female pleopod 11. D, paratype late preparatory female, 4.2 mm, right uropod.

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ervation or curation procedures. For example, if the INCAL samples were not buffered sufficiently when they were fixed in formaldehyde, the specimens would have been decalcified quickly, as seems to have been the case. Storing specimens in ethanol with more than 30% water can also cause decalcification, but at a slower rate.

Eurycope complanata Bonnier 1896 (Figures 9-11) Eurycope complanata: Bonnier 1896, p. 601; Wolff 1962, p. 147. Syntypes. Preparatory female, in poor condition (2 fragments), approximate length 4 mm, UCBZM. Juvenile male, length 3.2 mm, UCBZM. Adult male used in original description was dissected by Bonnier and apparently lost; published length 5 mm. A fourth specimen in the type-material does not belong to this species. Caudan station 13, 44"17'N, 4"38'W, 950 m. General Distribution. Bay of Biscay, 860-1920 m, see Table 1. Diagnosis. Adults 3.8-5.0 mm long, length 1.9-2.1 width. Rostrum narrow with slight or no overhang, rostral notch always shallow, rounded; rostral width 0.33-0.26 length, length 0.21 cephalon width. Cephalon widest anteriorly, postrostral cephalon length less than medial ambulosome length. Antennular article 1 medial lobe tip with 9-11 unequally bifid setae, longest seta 0.8 lobe length; article 2 shorter than medial lobe of article 1 (length ratio 0.9); third article distinctly longer than second article (length ratio 1.1-1.5). Maxillary mediobasal region without denticles or short recurved setae. Basis of pereopod VII with only one large seta on proximal posterior surface. Male pleopod I distal tip inner lobe subquadrate in ventral view, with distinct lateral shelf, length of inner lobe 0.31-0.40 distance between bases of outer lobes; outer lobes spinelike, curved ventrally, approximately as long as inner lobes. Male pleopod I1 vermiform appendage long, thin, with single terminal seta, length 0.14 protopod length. Female pleopod I1 keel length 0.9 pleopod length. Uropodal endopod slightly longer than width of protopod; exopod longer than half of endopod. Description of male. Body characters: dorsal surface with few fine setae on lateral margins; anterior margin of cephalon adjacent to lateral spine with 4-5 stout setae. Cephalic frons height 0.34 mouthfield depth; lateral spine length 0.88 frons height; frons anteriorly rounded, not perpendicular to body axis. Pleotelson length approximately 0.3 body length. Antennula (Fig. 9H, J):In individual from Galathea station 771 (tip broken off), length greater than 0.71 total body length, with more than 50 flagellar annuli. Mandibles (Fig. 10C-H): Mandibular condyle length subequal to molar process. Molar process with 8 setae on posterior margin, marginal denticles short and blunt. Spine row with 8 members. Lacinia mobilis with 8 denticles, three small denticles on dorsal margin. Palp second article 0.49 mandibular body length; distal article with 18 cleaning setae. Dorsal tooth of incisor process (both sides) with small denticle. Maxilla (Fig. 104: Inner lobe with no denticles or short curved setae at bases of long, thin medial setae. All three lobes near same length, but middle lobe shortest, outer lobe longest. Maxilliped (Fig. 10K-L): Basis with 5 receptaculi medially, 5 fan setae in row with two distinct gaps between lateral 3 setae and 2 compound spinelike setae distally; basis ventral


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Figure 9. Eurycope complanata Bonnier. A,J, copulatory male, 3.9 mm, Galathea 771. B, male syntype, 3.2 mm. C,I, female syntype fragment, D-H, copulatory male, 3.8 mm, Allen 40. A, dorsal view. B, lateral view. C, cephalon and ambulosome, dorsal view. D, lateral view of frons, rostrum, lateral spine, and labrum. E, lateral margins of pereonites 1-3. F, pereopods 1-111, coxae and bases. G, cephalon, right antennula and antenna removed, oblique frontal view. H, cephalon, dorsal view. I, cephalon, lateral view. J, male antennula.

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surface with 5-7 unequally bifid setae and 3-4 simple setae. Ischium narrower than endite of basis. Basis and ischium lack flat pointed projections on adjacent lateral margins. Merus width 1.3 endite width. Epipod slightly longer than basis, with 4 stout unequally bifid setae on ventral ridge. Pereopods (Fig. 9E-F):Bases of pereopods 1-111length to body length ratios 0.21,0.22, 0.22. Coxal plates of pereopods I-IV straight-sided and pointed. Pleopod I (Fig. 11A-E): Length 2.7 width with 4-5 pairs of hemiplumose setae on ventral surface.

Figure 10. Eurycope complanata Bonnier. A-C, F-G, I-L, copulatory male, 3.8 mm, Allen 40. D E , H, syntype preparatory female fragment. A, paragnaths. B, left mandible. C, molar process and condyle, posterior view. D, spine row, ventral view. E, palp, distal tip. F, molar process, medial view. G, incisor process and lacinia mobilis, posterior view. H, left and right mandibular tips, anterior view. I, maxillula. J, maxilla. K, maxilliped. L, maxillipedal endite, distal tip.


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Pleopod I1 (Fig. 11F-G): Lateral margin with 12-14 hemiplumose setae; protopod length 0.55 width. Stylet of endopod length 0.72 protopod length, distal tip sperm tube producing from thin cuticular sheath. Pleopods 111-V (Fig. 11H-J): Pleopod I11 exopod basal segment width 0.5 endopod width; pleopod IV 0.53. Pleopod V slightly wider than long, strongly cupped laterally. Uropod (Fig. 1lK): Endopod length 1.1 protopod width, width 0.26 length. Exopod 0.67 endopod length. Protopod lateral length 0.75 width; setal row with 22 members, longest seta greater than half width of protopod. Remarks. Although Eurycope complanata Bonnier (1896) is the first named member of this species group, it remains the least known. E. complanata lives somewhat shallower than the depths of the extensive French sampling programs (e.g., Laubier and Sibuet 1979) and does not appear in their collections. In addition to the male specimens available, only a single fragmentary female was examined for this species, so the above diagnosis and description are somewhat incomplete. Nevertheless, E. complanata is identified most easily by a cephalon that is widest anteriorly, a narrow nonoverhanging rostrum with a shallow anterior notch, a setose medial lobe of the antennular first article and an antennular third article that is distinctly longer than the second article. It shares the Bay of Biscay with E. centobi, n. sp. and E. iphthima Wilson 1981, but generally lives shallower than either of these. The former two species may co-occur in the northern part of the bay where E. complanata was collected by the Galathea at 1920 m. If so, the two species can be quickly rough-sorted by using both the differences in the sizes of adults and in the shapes of the rostra.

Figure 11. Eurycope complanata Bonnier. A, juvenile male syntype, 3.2 mm. B-C, E-K, copulatory male, 3.8 mm, Allen 40. D, copulatory male, 3.9 mm, Galathea 771. A-D, pleopod I distal tip; C, lateral view. E, pleopod I. F-G, male pleopod 11; G, dorsal view of endopod and exopod. H-J, pleopods 111-V. K, left uropod.

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Eurycope diadela, new species (Figures 12-13) Holotype. Late preparatory female, body length 6.8 mm, USNM 183770, from WHO1 340, 38"16'N, 70°22'W, 3310 m. Paratypes. Late preparatory female, body length 5.4, ZMUC; copulatory male, body length 6.3 mm, USNM 183771; copulatory male, body length 6.6 mm, ZMUC; 156 additional individuals, RRH. General Distribution. Abyssal rise off New England, USA, 3310-3806 m, see Table 1. Derivation of Name. Diadela is a Greek adjective meaning "distinguishable among others." Diagnosis. Adult body length 4.4-7.4 mm, instar 4 body length ca. 1.9 mm; adult length 2.1 width. Rostrum (Fig. 12C, I-J) small, somewhat broad, with deep V-shaped notch and some overhang: width 0.48-0.68 length; length 0.20-0.21 cephalon width; overhang 0.09-0.10 rostra1 length. Antennular article 1 medial lobe with 13-17 unequally bifid setae, longest seta 0.5-0.7 medial lobe length, males with more and longer setae; article 2 distinctly shorter than medial lobe (length ratio 0.7-0.8); third article in females subequal to second article, and in males shorter than second article (length ratios 1.0 and 0.86). Male pleopod I distal tip inner lobe tapering and rounded, with no lateral shelf; outer lobe length greater than half inner lobe length. Male pleopod I1 vermifornl appendage short and medially curving, with two small simple setae distally; length 0.07 protopod length. Uropodal endopod in males subequal to, and in females slightly greater than, protopod width; exopod greater than half endopod length. Description. Body characters (Fig. 12): Body dorsal surface nearly devoid of setae, except for very few simple setae on lateral margins. Cephalic frons height 0.27 mouthfield depth; lateral spine length 0.68 frons height. Antennula (Fig. 12K-M):In largest adult male, length 0.48 body length; flagellum 0.69 total length, with 77 annuli (40 in smallest adult males). In female, length 0.30 body length; flagellum 0.56 total length, with 22 annuli (adult female range 21-37 annuli). Left mandible (Fig. 13A): Molar process much shorter than condyle, length ratio 0.7; distal posterior edge with 6 setae; distal anterior edge enlarged, rounded and heavily cuticularized. Spine row with 9 members. Palp second article length 0.49 mandibular body length. Maxilla (Fig. 13B): Mediobasal region lacks denticles or small recurved setae. Maxilliped: Basis with 7-9 receptaculi medially and 4 stout and ca. 9 simple setae on ventral surface; distal row of 6 fan setae with distinct lateral gap. Epipod length 1.8 width, length slightly longer than basis, with 3-4 simple setae on ventral ridge, no stout setae. Pereopods I-IV (Fig. 12E): Basis-body length ratios 0.19, 0.19, 0.20, 0.21. Pereopod VII (Fig. 12N): Carpus length 1.1 width. Propodus length 0.9 carpus length. Pleopod I of male (Fig. 13C-D): Sympod length 3.9 width, with 8 hemiplumose setae on each side; inner lobe length 0.33 distance between bases of outer lobes. Pleopod I1 of male (Fig. 13E): Protopod length 1.3 width, with 18 hemiplumose setae on lateral margin. Stylet of endopod length 0.52 protopod length; distally pointed duct projects from tapering cuticular sheath. Pleopod I1 of female (Fig. 13F-G): Length 0.74 width, depth 0.3 length. Lateral margin with 10-11 hemiplumose setae on each side. Keel length 0.9 total length, 3.0 posterior


Figure 12. Eurycope diadela, n. sp. A-G, holotype late preparatory female, 6.8 mm. H-I, paratype copulatory male, 6.3 m i . J-L, N, paratype late preparatory female, 5.7 mm. M, paratype copulatory male, 6.4 mm. A-B, lateral and dorsal views. C, female rostrum, lateral oblique view. D, cephalon, lateral view. E, pereopods I-IV, coxae and bases. F-G, lateral margins of pereonites 1-7. H, dorsal view. I, male rostrum, dorsal oblique view. K-L, female left antennula. M, male left antennula. N, left pereopod VII.

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margin length. Posterior margin in lateral view distally perpendicular to body axis, slopes proximal to apex at approximate 45" angle to keel. Uropod (Fig. 13J): In female, endopod length 1.06 protopod width, length 0.27 width; exopod length 0.55 endopod length. In large male, endopod length 0.97 protopod width, length 0.30 width; exopod length 0.63 endopod length. Protopodal setal row with 22 members. Remarks. Eurycope diadela is very closely related to E. propilosa, which occurs in a similar but shallower depth range off Guiana. Both species are similar in size, at least in the juvenile stages, and the male pleopods of both are nearly identical. Eurycope diadela is distinguished from E. propilosa in lacking dorsal body setae, and in having a rostrum with a deep V-shaped notch and a uropodal exopod that is longer than half the length of the endopod. The lower edge of E. diadela's vertical range overlaps the upper edge of E. iphthima's range: the former species was taken at WHOI 126 (3806 m), while the latter was collected at WHOI 85 (3834 m) and WHOI 95 (3753 m). Because these species were not taken in the same sample, their actual ranges may interdigitate, perhaps depending on local environmental conditions. Eurycope diadela is easily separated from the neighboring species, even in poorly preserved samples in the area of the type-locality: if the maxillary mediobasal region lacks denticles, it is this species; if they are present, it is E. iphthima. In well-preserved condition, the two species are easily distinguishable and may be readily keyed out.

Figure 13. Eurycope diadela, n. sp. A-B, F-J, paratype late preparatory female, 5.7 mm. C-E, paratype copulatory male, 6.4 mm. A, left mandible. B, maxillary mediobasal region. C-D, pleopod I. E, male pleopod 11. F-G, female pleopod 11. H-I, pleopods 111-IV. J, right uropod.


Eurycope grasslei, new species (Figures 14-15) Eurycope complanata (not of Bonnier 1896): Hansen 1916, pp. 145-146, pars. Holotype. Late preparatory female, body length 5.3 mm, USNM 183768, from WHO1 66, 3g046'N, 70"08'W, 2802 m. Paratypes. Ten individuals, RRH. General Distribution. Bathyal slopes off New England, USA, and in the Davis Strait, 2086-2891 m, see Table 1 . Derivation of Name. This species is named in honor of Dr. J. Frederick Grassle, Woods Hole Oceanographic Institution, whose efforts have significantly advanced deep-sea ecology. Diagnosis. Adult body length 4.2-6.7 mm, instar 4 (juvenile 1 ) mean length 2.4 mm (SD = 0.1); length 2.2 width. Rostrum (Fig. 14D-G) not extremely variable, moderately broad, with sloping U-shaped notch and no overhang; width-length ratio 0.44 in male, 0.65 in female; length 0.20 cephalon width. Antennular article 1 medial lobe with 5 unequally bifid setae, longest seta 0.9 medial lobe length; article 2 shorter than medial lobe (length ratio 0.8-0.9), third article in females longer than, and in males shorter than, article 2 (length ratios 1.1 and 0.8). Maxillary mediobasal region with 7 denticles at insertions of long thin setae. Male pleopod I length 3.2 width, with 5-7 hemiplumose setae; distal tip inner lobe truncate in ventral view, with flat lateral shelf; outer lobe tapers to thin, spinelike process closely adjacent to inner lobe; outer lobe slightly longer than inner lobe. Male pleopod I1 vermiform appendage long and thin, length 0.16 protopod length. Uropodal endopod longer than protopod width; exopod longer than half endopod length. Description. Body characters (Fig. 14A-B, F-H): Body with scattered setae only on lateral margins of pereonites. Cephalic frons height 0.30 mouthfield depth, lateral spine length 0.58 frons height. Pleotelson length 0.87 width, length 0.33 body length. Antennula (Fig. 140, J):In male, length 0.56 body length; flagellum length 0.69 total length, with 37 annuli. In female, length 0.31 body length; flagellum length 0.49 body length, with 16 annuli. Mandible (Fig. 15A): Molar shorter than condyle, with 7 setae on distal posterior surface; anterior surface somewhat rounded and enlarged. Spine row with 9 members. Lacinia mobilis with 8 denticles. Palp second article 0.43 mandibular body length. Maxilliped (Fig. 15C-D): Basis with 6 receptaculi medially, and 7 stout setae and approximately 8 tiny simple setae on ventral surface; distal row of 5 fan setae with distinct lateral gap. Adjacent lateral margins of basis and ischium protrude slightly anteriorly from insertions, lateral margin of ischium pointed, spinelike. Epipod length 1.9 width, length slightly longer than basis; ventral ridge with three stout setae. Pereopod VII (Fig. 141): Carpus length 1.1 width. Propodus length 0.99 carpus length. Pleopod I of male (Fig. 15E-F):Distal tip inner lobe length 0.40 distance between bases of outer lobes. Pleopod I1 of male (Fig. 15G): Protopod length 1.8 width, with 12 hemiplumose setae on lateral margin. Stylet of endopod length 0.77 protopod length; distally truncate sperm duct projects from tapering cuticular sheath.

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Figure 14. Eurycope grasslei, n. sp. A-E, holotype female, 5.0 mm. F-G, I , paratype late preparatory female, 5.5 mm. H, J-K, copulatory male, 5.0 mm, WHO1 64. A-B, lateral and dorsal views. C, lateral margins of pereonites 1-4, cuticular ridges shown only on pereonite 3. D, antennula and rostrum, dorsal oblique view. E, rostrum, oblique view. F, cephalon, left antennula and antenna removed, frontal oblique view. G, lateral view of rostrum, frons, lateral spine, and labrum. H, dorsal view. I, pereopod VII. J, right antennula. K, left uropod.


29

Pleopod I1 of female (Fig. 15H): Length 1.2 width, keel length 0.89 total length. Lateral margin with 14 hemiplumose setae. Posterior margin in lateral view nearly perpendicular to keel. Uropod (Fig. 14K): Endopod length 1.1 protopod width; width 0.27-0.29 length. Exopod length 0.61-0.63 endopod length. Protopodal setal row with 19-22 members. Remarks. Eurycope grasslei is a sibling species of Eurycope iphthima. They share most diagnostic characters, particularly the dentate mediobasal region of the maxilla, as well as general body shape and size. These similarities and variability in E. iphthima make the two species difficult to separate routinely. Table 2 provides a detailed comparison of a number of taxonomic features that will allow identification of the species. Of the characters, the inner ramus of the uropod is the most immediately useful: in E. grasslei, the endopod is longer than the width of the protopod, while in E. iphthima, it is shorter. The rostral characters are also useful if the rarity of wide rostra with no overhang is recognized in E. iphthima. Eurycope grasslei often co-occurs with E. sandersi, so care should be taken with rough-sorting samples where either are found. Their general body size and rostral shape are most useful for rapid separation of the two species.

Figure 15. Eurycope grasslei, n. sp. A-D, H-K, paratype late preparatory female, 5.5 mm. E-G, copulatory male, 5.0 mm, WHO1 64. A, left mandible. B, left maxillary mediobasal denticles. C-D, left maxilliped; C, palp setae omitted; D, setation of distal merus and carpus. E-F, pleopod I; F, enlargement of distal tip. G, male pleopod 11. H-K female pleopods 11-V.

TABLE 2 A character comparison of Eurycope grasslei and E. iphthima.

Character

E. grasslei

E. iphthima

22 2

"S.

Uropodal endopod lengthlprotopod width Female antennular article 3 lengthlarticle 2 length Male Pleopod I lengthtwidth hemiplumose setae on ventral surface inner lobe lengthtdistance between bases of outer lobes Male pleopod I1 stylet length/ protopod length Rostrum overhangllength Rostrum widthtlength

0.69-0.71 (0.0)-0.33 median 0.28 0.22-0.64 median 0.36


Eurycope iphthima Wilson 1981 (Figure 16) Eurycope iphthima: Wilson 1981, p. 226. Eurycope complanata (not of Bonnier 1896): Menzies 1962, pp. 141-142; Chardy 1975, p. 3, in part; Chardy 1979, p. 81, in part. Eurycope cf. complanata: Wolff 1975, pp. 223-224, in part (not of Bonnier 1896). Holotype. Late preparatory female, body length 7.0 mm, USNM 181106, from WHOI 326, 50°05'N, 14"24'W, 3859 m. Paratypes. Ten individuals, USNM 181107; 5 individuals, AMNH 16253; 5 individuals ZMUC; 273 individuals, RRH. General Distribution. Rise and slopes of the northeastern Altantic, and abyssal northwestem Atlantic, 2379-5000 m, see Table 1. Diagnosis. Adults reach maturity above 4 mm length, maximum observed size 7.4 mm; instar 4 mean length 2.2 mm (SD = 0.1). Body length 2.0-2.2 width. Rostrum (Fig. 16A-D) variable; almost always with some overhang, especially when narrow; with U- or

Figure 16. Eurycope iphthima Wilson. A, D , late preparatory female, WHOI 334. B-C, E, late preparatory females, WHOI 326. F-H, copulatory male, WHOI 334. A-C, lateral views of frons, rostrum, lateral spine, and labrum. D, rostrum, dorsal and oblique views. E, maxilla with enlargement of mediobasal denticles. F, pleopod I. G-H, male pleopod 11. H, stylet distal tip.

V-shaped notch. Antennular article 1 medial lobe with 5-7 unequally bifid setae, longest seta 0.7-0.8 medial lobe length; article 2 slightly longer than or subequal to medial lobe; third article subequal to or shorter than second article (length ratio 0.82-1.0); male antennular articles shorter than in female. Maxillary mediobasal region with denticles at insertions of long thin setae. Male pleopod I length 3.6-3.7 width, with 9-10 hemiplumose setae; distal tip inner lobe subquadrate in ventral view, with flat lateral shelf; inner lobe length 0.5 distance between bases of outer lobes; outer lobes spinelike and curved, closely adpressed to inner lobes, shorter than inner lobes. Male pleopod I1 vermiform appendage long and thin, length 0.15-0.16 protopod length. Uropodal endopod shorter than protopod width; exopod longer than half endopod length. Description. This species is treated in detail in Wilson (1981). Remarks. Eurycope iphthima is a sibling species of E. grasslei; they may be separated using uropodal and male pleopodal characters (Table 2; see discussion under E. grasslei). The diagnosis has been modified from Wilson (1981) to parallel the other species of the complanata complex.

BODY

LENGTH,

mm.

Figure 17. Eurycope iphthima Wilson. Rostra1 lengths versus body lengths for two stations separated by 2573 km, WHOI 334 and WHOI 328. An analysis of covariance (F, ,, = 33.25) shows the difference in rostra1 lengths between these two stations to be highly significant (p