Contumacious Beasts: a Story of Two Diastylidae (Cumacea) from Arctic Waters S

The University of Maine DigitalCommons@UMaine

Marine Sciences Faculty Scholarship School of Marine Sciences

2-1-2000 Contumacious Beasts: A Story of Two Diastylidae (Cumacea) from Arctic Waters S. Gerken

Les Watling University of Maine - Main, [email protected]

A. B. Klitgaard

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Repository Citation Gerken, S.; Watling, Les; and Klitgaard, A. B., "Contumacious Beasts: A Story of Two Diastylidae (Cumacea) from Arctic Waters" (2000). Marine Sciences Faculty Scholarship. 28. https://digitalcommons.library.umaine.edu/sms_facpub/28

This Article is brought to you for free and open access by DigitalCommons@UMaine. It has been accepted for inclusion in Marine Sciences Faculty Scholarship by an authorized administrator of DigitalCommons@UMaine. For more information, please contact [email protected]. JOURNAL OF CRUSTACEAN BIOLOGY, 20(1): 31Ð43, 2000

CONTUMACIOUS BEASTS: A STORY OF TWO DIASTYLIDAE (CUMACEA) FROM ARCTIC WATERS

Sarah Gerken, Les Watling, and Anne B. Klitgaard

(SG, LW) Darling Marine Center, University of Maine, Walpole, Maine 04573, U.S.A. (SG e-mail: [email protected]); (ABK) Zoological Museum, University of Copenhagen, Universitetsparken 15, DK 2100 Copenhagen, Denmark

ABSTRACT A full description of the subadult male holotype of the diastylid Ektonodiastylis robusta, new genus, new species, is presented, as well as of the adult male and adult female of E. nimia. Ek- tonodiastylis nimia is transferred from Brachydiastylis to Ektonodiastylis. The family deﬁnition of Diastylidae is expanded. The implications of this expansion on the systematics of the Cumacea in general, and Diastylidae and Gynodiastylidae in particular, are discussed.

A recent visit to the Zoologisk Museum, in the family Diastylidae; in the genus At- Copenhagen, by one of us (SG) included the lantistylis, pleopods are completely absent in opportunity to inspect material collected by males. The material described herein repre- a 1995 Danish marine biological expedition sents the first case of a male with one pair of to Independence Fjord in northeastern Green- pleopods. land. Independence Fjord is approximately 200 km long and 20 km wide at the maximum MATERIALS AND METHODS width, and covered with ice year-round. In the Samples from Independence Fjord were collected with summer, long leads form in the ice due to an Ockelmann detritus dredge through holes or leads in the ice, at depths of 20Ð200 m. The sample from the tidal movements. The expedition to Indepen- Canadian Arctic was obtained with a grab and had been dence Fjord, led by Dr. Eigeil Knuth, fol- stored in the collections of the Canadian Arctic Biolog- lowed the framework of the Danish Peary ical Station, Sainte Anne de Bellevue, Quebec. These col- Land Expeditions. The purpose of the expe- lections have now been moved to the Canadian Museum of Nature in Ottawa. Drawings were prepared using a dition was to collect faunistic data for com- camera lucida mounted on a Wild compound microscope. parison with similar work done in the much Body length was measured from the tips of the pseudoros- smaller J¿rgen Br¿nlund Fjord (Schiotte, tral lobes to the posterior border of the last body somite. 1989). Within the Independence Fjord material, a SYSTEMATICS species was found that appeared to fit the description of Brachdiastylis nimia Hansen, Family Diastylidae Bate, 1856 1920, described from eastern Greenland; Diagnosis (modified after Day, 1980).—Fla- however, the males possessed only one pair gellum of antenna 2 of male with many short of pleopods. Hansen’s material did not in- segments and reaching at least to posterior clude males, whereas the new specimens from end of thorax. Mandible normally navicular northeastern Greenland include an abundance (boat-shaped) but truncated above molar in of subadult males and a single adult male, Diastyloides. Branchial filament divided into along with females of all stages. A single pair numerous leaflets. Exopods present on max- of pleopods was present in all males exam- illiped 3 and pereiopods 1Ð4 in males, pre- ined and, therefore, is not an instance of a sin- sent in female on maxilliped 3 (except in gle contumacious (=rebellious, disobedient) Paradiastylis) and on pereiopods 1Ð2, rudi- individual. mentary on or absent from pereiopods 3 and In addition, within a collection of isopods 4. Male with no pleopods (Atlantistylis), one from the Canadian Arctic, another subadult (Ektonodiastylis) or two pairs of pleopods (all male cumacean was discovered that also pos- other genera); no outer process on inner ra- sessed a single pair of pleopods. Males with mus of pleopod. Telson variable, usually fewer than two pairs of pleopods are unusual large, often with long postanal part, or short

31 32 JOURNAL OF CRUSTACEAN BIOLOGY, VOL. 20, NO. 1, 2000 E. robusta. m C, habitus of holotype subadult E. nimia; m B, habitus of adult Ektonodiastylis nimia; f Fig. 1. A, habitus of ovigerous GERKEN ET AL.: CONTUMACIOUS ARCTIC CUMACEA 33 and poorly armed; bearing one pair of termi- Diagnosis.—Carapace produced as large nal setae or none. Uropods usually long and tooth at anteroventral corner, pseudorostral slender, endopod 1Ð3-segmented. lobes directed nearly horizontally, pereionites 3 and 4 directed posteroventrally, telson shorter than uropod peduncles, uropod exo- Ektonodiastylis, new genus pod length greater than twice endopod length. Type Species.—Ektonodiastylis nimia is des- Adult individuals near 3 mm in length. ignated as the type species; complete de- scriptions of both ovigerous f and adult m are Description.—Adult male. Length 3.3 mm. provided herein. Type material is that de- Pseudorostral lobes 0.6 times carapace total posited by Hansen (1920). However, it should length, bearing many plumose setae, eye lobe be noted that his syntypes are in poor shape. 0.1 times carapace length, with no lenses; carapace produced as large spine at antero- Diagnosis.—Male with 1 pair of pleopods, ventral corner, otherwise smooth; antennal pereiopod 2 dactyl minute and attached prox- notch oblique (Fig. 1B). imally to distal end of propodus. Antennule stout, extending beyond Etymology.—The generic name is a combi- pseudorostral lobes; peduncle articles 1 and nation of ektonos, Greek, meaning out of 2 together slightly longer than article 3, un- tune, and diastylis, from the family Diastyl- armed; peduncle article 3 dorsal margin bear- idae. ing 4 long stout plumose setae, 2 small simple setae on distal margin; main flagellum of Other Species.—Ektonodiastylis robustus, 6 articles, article 1 expanded and bearing new species. many slender simple setae, 3 terminal articles bearing several simple setae; accessory fla- Remarks.—This genus is very similar to gellum of 4 articles, extending to distal mar- Brachydiastylis, distinguishable at present gin of main flagellum article 3, bearing few only on male characters, primarily the pos- simple setae terminally (Fig. 2A). session of a single pair of pleopods. The pe- Antenna long, extending past pereion but culiar arrangement of the dactyl and propo- not extending to end of pleon; peduncle arti- dus on pereiopod 2 is also unusual and seems cle 3 bearing 2 plumose setae, twice as long derivable from the condition seen in Brachy- as article 4; article 4 unarmed; article 5 2.5 diastylis, namely, the extension of the prop- times as long as article 3, anterior margin odus forms a large fixed finger, but in Ek- bearing 6 groups of short simple setae; fla- tonodiastylis the dactyl is reduced to a small gellum of 20 articles, articles decreasing in article that most likely is not movable, since width and increasing in length distally, each there is no associated musculature in the article bearing 2 or 3 rows of small slender propodus. Hansen (1920) noted the unusual setae (Fig. 2B). pereiopod 2 in the male of Brachydiastylis Mandibles, maxillulae, maxillae, maxil- resima and presumed it would also occur in liped 1, and maxilliped 2 as in female. his new species B. nimia, but he had no ma- Maxilliped 3 basis longer than all other ar- ture males. The other species of Brachydi- ticles together, 3 times as broad as merus, me- astylis, B. hexaceros Lomakina, 1952, is be- dial and lateral margins lined with fine hair- ing left in the genus for the time being, since like setae, bearing 2 plumose setae medially, the mature male is not known. distolateral corner bearing 3 stout plumose setae, distomedial corner produced as 2 teeth; ischium compressed, unarmed; merus sub- Ektonodiastylis nimia (Hansen, 1920), equal to carpus, bearing 1 plumose seta lat- new combination erally; carpus bearing 2 plumose setae dis- Material Examined.—Syntypes: 2 ovigerous tally; propodus and dactyl subequal, propo- ff (ZMUC CRU–3437) “North of Steward dus bearing 2 sparsely plumose setae Land,” 70°30′N. Additional material exam- medially, 1 small plumose seta at distolateral ined: 41 ovigerous ff, 94 subadult ff, 1 adult corner; dactyl bearing 6 simple setae apically; m, 73 subadult mm (ZMUC CRUÐ3573), In- exopod shorter than basis, basal article un- dependence Fjord, Greenland, 4 August 1995, armed, flagellum bearing 10 long, stout 82¡07.06′N, 29¡51′W, 35Ð 40 m. plumose setae (Fig. 2C). 34 JOURNAL OF CRUSTACEAN BIOLOGY, VOL. 20, NO. 1, 2000

Fig. 2. Ektonodiastylis nimia adult m. A, antennule; B, antenna; C, maxilliped 3; D, pereiopod 1; E, pereiopod 2.

Pereiopod 1 basis as long as next 4 arti- plumose seta; merus anterior margin bearing cles together, posterior margin bearing 4 2 plumose setae; carpus and propodus sub- plumose setae, anterior margin bearing 1 equal and unarmed; dactyl shorter than prop- plumose seta distally; ischium and merus sub- odus, bearing 3 simple setae apically and 4 equal, ischium anterior margin bearing 1 simple setae marginally; exopod as long as GERKEN ET AL.: CONTUMACIOUS ARCTIC CUMACEA 35 basis and ischium together, basal article un- plumo-annulate seta distally; merus bearing armed, flagellum bearing 12 long, stout 2 annulate setae marginally; carpus as long as plumose setae (Fig. 2D). propodus and dactyl together, with 4 annulate Pereiopod 2 basis slightly longer than next setae; propodus subequal to dactyl, bearing 3 articles together, anterior margin bearing 1 1 stout annulate seta and 1 slender plumose plumose seta, posterior margin bearing 5 long seta; dactyl bearing 1 slender seta marginally plumose setae; ischium compressed, bearing and 2 stout simple setae terminally (Fig. 3C). 1 plumose seta at distal posterior corner; One pleopod pair present; pleopod basal ar- merus 3 times ischium length, unarmed; car- ticle 3.5 times length of rami, medial margin pus 4 times merus length, posterior margin bearing 2 simple and 2 long plumose setae; bearing 5 simple setae; propodus one-third medial ramus uniarticulate, bearing 4 long, carpus length, extended distally as fixed fin- stout plumose setae apically; lateral ramus bi- ger beyond insertion of dactyl, ridge at base articulate, bearing 2 long, stout plumose se- of fixed finger bearing 3 small setae; dactyl tae terminally (Fig. 3D). minute, bearing several slender simple setae; Telson 1.9 times length of pleonite 6, pre- exopod extending beyond merus, basal arti- anal section longer than postanal section, pre- cle bearing 1 plumose seta, flagellum bear- anal section unarmed, postanal section lateral ing 14 long, stout plumose setae (Fig. 2E). margins bearing 1 pair of slender setae and Pereiopod 3 basis longer than all other ar- 2 pairs of stout setae, 1 pair of long mi- ticles together, anterior margin with 2 small croplumose setae terminally, stout setae short setae, bearing 1 plumose and 1 simple setae with 1 subapical setule (Fig. 3E). distally; ischium one-third length of merus, Uropod peduncles longer than telson, bearing 1 plumose seta anteriorly; merus an- shorter than exopods, medial margins bearing terior margin having 4 stout and 2 slender 5 stout microplumose setae; endopod 0.55 simple setae; carpus one-half merus length, times length of exopod, of 3 articles, article bearing 7 stout annulate setae, increasing in 1 longest, medial margin bearing 3 stout mi- length distally; propodus subequal in length croplumose setae, article 2 medial margin to carpus, with 1 long, stout annulate seta dis- bearing 2 stout microplumose setae, article 3 tally; dactyl two-thirds propodus length, bear- medial margin with 1 stout microplumose ing 1 slender simple seta marginally, 2 stout seta, lateral margin bearing 1 small simple simple setae terminally; exopod as long as ba- seta, and with 1 very long microplumose seta sis, ischium, and merus together, basal article terminally; exopod of 2 articles, article 1 0.25 unarmed, flagellum bearing 12 long, stout times length of article 2, unarmed, article 2 plumose setae (Fig. 3A). lateral margin bearing several small simple Pereiopod 4 basis about as long as all other setae, and with 3 extremely long, micro- articles together, distal anterior corner bear- plumose setae terminally (Fig. 3E). ing 1 plumose seta, posterior margin bearing Ovigerous female. Length 3.7 mm. Cara- 1 pedunculate seta A; ischium anterior mar- pace with several teeth on anterior portion of gin bearing 2 plumose setae; merus as long dorsal crest, pseudorostral lobes 0.5 times to- as next 3 articles together, anterior margin tal carapace length, bearing many setae, 1 with 4 short annulate setae; carpus as long tooth below pseudorostral lobe, carapace an- as propodus and dactyl together, bearing 7 teroventral corner produced as large tooth, an- long, stout annulate setae, increasing in length tennal notch oblique, ventral margin lined distally; propodus and dactyl subequal in with teeth, eyelobe not present; pereionites 1 length, propodus bearing 1 long, stout annu- and 2 free and not covered by carapace, late seta distally, 1 pedunculate seta A dis- pereionites 3Ð5 produced posteroventrally, tally; dactyl bearing 1 slender simple seta large separation between pereionites 2 and 3 marginally, 2 stout simple setae terminally; ventrally (Fig. 1A). exopod longer than basis and ischium to- Antennule extending past pseudorostral gether, basal article unarmed, flagellum bear- lobes; article 1 1.6 times as long as article 2, ing 14 long, stout plumose setae (Fig. 3B). mediodistal corner produced as tooth, other- Pereiopod 5 basis as long as next 3 arti- wise unarmed; article 2 bearing 1 peduncu- cles together, bearing 2 simple and 2 plumose late seta A medially; article 3 longer than ar- setae distally, 1 pedunculate seta marginally; ticles 1 and 2 together, dorsal margin bear- ischium half length of merus, bearing 1 ing 4 plumose setae, few small simple setae, 36 JOURNAL OF CRUSTACEAN BIOLOGY, VOL. 20, NO. 1, 2000

Fig. 3. Ektonodiastylis nimia adult m. A, pereiopod 3; B, pereiopod 4; C, pereiopod 5; D, pleopod; E, telson and uropods. laterodistal corner bearing 1 pedunculate seta; main flagellum, with few simple setae termi- main flagellum of 4 articles, bearing several nally (Fig. 4A). simple setae terminally; accessory flagellum Antenna rudimentary, of 3 articles, bear- of 1 article, slightly longer than article 1 of ing 1 plumose seta terminally (Fig. 4B). GERKEN ET AL.: CONTUMACIOUS ARCTIC CUMACEA 37

Fig. 4. Ektonodiastylis nimia ovigerous f. A, antennule; B, antenna; C, mandible; D, maxillule; E, maxilla; F, maxilliped 1; G, maxilliped 2; H, maxilliped 3.

Mandible navicular, lifting row of 7 setae; Maxillule of 2 lobes, broad lobe lateral left mandible with stout, tricuspidate lacinia margin bearing 1 simple seta, medial margin mobilis, incisor with 6 cusps; right mandible with many fine hairlike setae, distal margin with slender lacinia mobilis, incisor with 5 bearing 2 rows of 5 stout setae; narrow lobe cusps (Fig. 4C). distal margin having 4 setae of varying 38 JOURNAL OF CRUSTACEAN BIOLOGY, VOL. 20, NO. 1, 2000 lengths; palp bearing 2 long setae (Fig. 4D). ticle covered with scales; ischium two-thirds Maxilla with 3 lobes, broad lobe distolat- merus length, posterodistal corner bearing 1 eral corner bearing 1 plumose seta, distal mar- plumose seta; merus unarmed; carpus and gin with many simple setae, 1 pappose seta merus subequal in length, bearing 1 simple at distomedial corner, medial portion of lat- seta; propodus bearing 3 simple setae; dactyl eral margin bearing several sparsely plumose one-half length of carpus, bearing 6 simple setae; narrow lateral lobe bearing 5 simple se- setae marginally, 3 long simple setae termi- tae terminally; medial narrow lobe bearing 3 nally; exopod longer than basis and ischium or 4 simple setae terminally (Fig. 4E). together, basal article anterior margin pro- Maxilliped 1 basis medial margin bearing duced as 5 teeth, otherwise unarmed, flagel- several simple setae and 1 pappose seta dis- lum bearing 6 long, stout plumose setae (Fig. tally, produced as lobe medially, lobe bear- 5A). ing 2 hooks, anterior face with several ranks Pereiopod 2 reduced, basis slightly longer of small fine hairlike setae; ischium not pres- than next 4 articles together, posterior margin ent; merus not as long as carpus, bearing few produced as 2 teeth, bearing 1 simple and 3 simple setae; carpus distolateral corner bear- plumose setae, anterior margin bearing 1 sim- ing 1 long plumose seta, medial face carry- ple seta; ischium compressed, posterior mar- ing many simple setae; propodus bearing 2 gin bearing 1 plumose seta; merus one-half plumose setae distally, medial face bearing carpus length, posterodistal corner bearing 1 many simple setae; dactyl one-third width of simple seta; carpus posterodistal corner with propodus, not as long as propodus, bearing 3 2 simple setae; propodus not as long as car- simple setae terminally (Fig. 4F). pus, posterodistal corner bearing 1 simple Maxilliped 2 basis distal margin bearing 3 seta; dactyl not as long as propodus, bearing plumose setae; ischium unarmed; merus with 1 simple seta marginally, 3 simple setae ter- 1 plumose seta at each distal corner, disto- minally; exopod about as long as endopod, lateral margin lined with fine hairlike setae, basal article unarmed, flagellum with 6 long, face bearing several rows of fine hairlike se- stout plumose setae (Fig. 5B). tae; carpus as long as propodus and dactyl to- Pereiopod 3 basis as long as all other arti- gether, distolateral corner with 1 plumose cles together, posterior margin produced as seta, medial margin bearing 5 plumose setae; 1 large tooth, bearing 4 plumose and 1 plumo- propodus lateral margin with 2 plumose se- annulate setae, anterior margin bearing 3 sim- tae, medial margin bearing 6 simple setae; ple setae; ischium 0.25 times length of merus, dactyl less than one-half length of propodus, bearing 2 annulate setae; merus with 4 short bearing 3 slender and 1 very stout simple se- annulate setae marginally; carpus one-half tae apically (Fig. 4G). merus length, anterior margin bearing 7 stout Maxilliped 3 basis longer than all other ar- annulate setae, increasing in length distally; ticles together, medial margin bearing several propodus one-half length and one-half width plumose and 1 simple setae, distolateral cor- of carpus, bearing 1 stout annulate seta and ner bearing 4 long, stout plumose setae, me- 1 pedunculate seta A distally; dactyl bearing dial margin produced as several teeth/scales; 1 slender simple seta marginally, with 2 stout ischium compressed, unarmed; merus pro- simple setae terminally; exopod not present duced as 2 teeth medially, distolateral corner (Fig. 5C). bearing 1 plumose seta; carpus longer than Pereiopod 4 basis as long as next 3 arti- merus, produced as 1 tooth medially, disto- cles together, posterior margin bearing 5 medial corner bearing 1 plumose seta; prop- plumose setae, anterior margin bearing 2 slen- odus subequal to carpus, with 2 plumose se- der simple setae, 2 pedunculate setae A; is- tae medially; dactyl two-thirds carpus length, chium 0.25 times length of merus, posterior bearing 6 simple setae terminally; exopod margin bearing 2 annulate setae; merus pos- shorter than basis, basal article unarmed, fla- terior margin having 5 annulate setae; carpus gellum bearing 4 long, stout plumose setae less than one-half length of merus, anterior (Fig. 4H). margin bearing 7 stout annulate setae, in- Pereiopod 1 basis longer than next 2 arti- creasing in length distally; propodus slightly cles together, posterior margin produced as shorter than carpus, one-half width of carpus, 2 large teeth, bearing 3 plumose setae, ante- bearing 1 annulate seta distally; dactyl one- rior distal margin bearing 3 plumose setae, ar- half length of propodus, bearing 1 slender seta GERKEN ET AL.: CONTUMACIOUS ARCTIC CUMACEA 39

Fig. 5. Ektonodiastylis nimia ovigerous f. A, pereiopod 1; B, pereiopod 2; C, pereiopod 3; D, pereiopod 4; E, pereiopod 5; F, telson and uropods. marginally and 2 stout simple setae termi- plumose setae, anterior margin bearing 1 pe- nally; exopod not present (Fig. 5D). dunculate seta and 1 simple slender seta; is- Pereiopod 5 basis longer than next 2 arti- chium one-half length of merus, posterior cles together, posterior distal corner with 2 margin bearing 1 annulate seta; merus poste- 40 JOURNAL OF CRUSTACEAN BIOLOGY, VOL. 20, NO. 1, 2000 rior margin bearing 2 annulate setae; carpus of teeth dorsally, 1 tooth on anteroventral two-thirds length of merus, anterior margin margin; pereionites 3 and 4 oriented hori- with 5 stout annulate setae; propodus one-half zontally rather than vertically, pereionite 4 length and one-half width of carpus, bearing dorsal to pereionite 3, each with few teeth on 1 stout annulate seta distally; dactyl not as margins; pereionite 5 also oriented mostly long as propodus, bearing 1 slender simple horizontally, produced bluntly posteriorly seta marginally, 2 stout simple setae termi- (Fig. 1C). nally (Fig. 5E). Antennule extending beyond pseudorostral Telson 1.8 times as long as pleonite 6, pre- lobes, very stout; peduncle article 1 longer anal and postanal sections subequal, postanal than article 2, distodorsal corner bearing 1 section lateral margins bearing 3 pairs of slen- plumose seta; peduncle article 2 unarmed; pe- der setae, with 1 pair of long microplumose duncle article 3 longer than article 1, dorsal setae terminally (Fig. 5F). margin bearing 8 long plumose setae, ven- Uropod peduncles longer than telson, mar- tral margin having 2 small simple setae; main gins lined with many fine short hairlike se- flagellum of 6 articles, articles 4 and 5 bear- tae, lateral margin bearing 5 slender simple ing 1 simple seta distally, article 6 bearing setae, medial margin bearing 3 slender sim- many simple setae terminally; accessory fla- ple setae; endopod 0.25 times length of exo- gellum of 4 articles, extending to middle of pod, of 3 articles, article 1 longest and un- article 4 of main flagellum, with 3 simple se- armed, article 2 distomedial corner with 1 tae terminally (Fig. 6A). stout seta, distolateral corner bearing 1 pe- Antenna extending past posterior margin of dunculate seta and 1 small simple seta, arti- carapace, this individual being subadult; pe- cle 3 distomedial corner with 1 stout seta, duncle article 4 slightly shorter than article 5, bearing 1 long microplumose seta terminally, bearing 5 plumose setae; article 5 unarmed; medial and terminal setae all with 1 setule flagellum of 22 articles, increasing in length subapically; exopod of 2 articles, article 1 0.2 and decreasing in width distally, articles un- times length of article 2, unarmed, article 2 armed (Fig. 6B). lateral margin bearing 8 slender simple se- Maxilliped 3 basis longer than all other ar- tae, with 3 very long plumose setae terminally ticles together, twice as broad as merus, me- (Fig. 5F). dial margin produced as several stout teeth, medial margin bearing 6 plumose setae, ridge Ektonodiastylis robusta, new species down center of article bearing several more m plumose setae, lateral margin lined with many Material Examined.—Holotype, subadult fine hairlike setae, distal margin bearing 4 (CMNC 1998Ð0017), Foxe Basin, Repulse ′ ′ long, stout plumose setae; ischium com- Bay, 66¡28 N 86¡16 W, rock/sand/mud, 23 pressed, unarmed; merus medial margin pro- August 1961. duced as 1 stout tooth, distolateral corner Diagnosis.—Pseudorostral lobes directed dor- bearing 1 long, stout plumose seta; carpus sally in subadult male, pereionite 4 directly subequal to merus, medial margin produced dorsal to pereionite 3, telson subequal to uro- as 1 tooth and bearing 1 long stout and 1 slen- pod peduncles, uropod exopod length 1.5 der plumose setae, lateral margin bearing 2 times endopod length. slender setae distally; propodus longer than carpus, bearing 2 plumose setae medially and Etymology.—The specific name robusta in- 1 plumose seta distolaterally; dactyl with 3 dicates that the individual is larger and more simple setae marginally, 2 long simple setae robust than E. nimia. and 1 microserrate seta terminally; exopod as Description.—Subadult male. Length 5.1 long as basis, ischium, and merus together, mm. Carapace 0.6 times as deep as long, an- basal article bearing few setae, flagellum terior one-third of dorsal crest lined with bearing 10 long, stout plumose setae (Fig. teeth, 1 tooth below pseudorostral lobes, 6C). pseudorostral lobes bearing many long Pereiopod 1 basis as long as next 4 arti- plumose setae, sharply directed dorsally, an- cles together, anterior, posterior, and distal tennal notch oblique, carapace ventral margin margins lined with plumose setae, posterior lined with teeth; pereionite 1 free and not margin produced as 1 tooth, center of article covered by carapace; pereionite 2 with row also produced as 1 tooth; ischium one-half GERKEN ET AL.: CONTUMACIOUS ARCTIC CUMACEA 41

Fig. 6. Ektonodiastylis robusta holotype subadult m. A, antennule; B, antenna; C, maxilliped 3; D, pereiopod 1; E, pereiopod 2; F, pereiopod 3; G, pereiopod 4; H, pereiopod 5; I, pleopod. merus length, unarmed; merus unarmed; car- simple setae, ﬂagellum bearing 12 long, stout pus and propodus subequal, bearing few short plumose setae (Fig. 6D). simple setae marginally; dactyl not as long Pereiopod 2 basis expanded laterally, as propodus, bearing 6 slender simple setae longer than all other articles together, 3 times marginally, 2 stout simple setae terminally; as broad as carpus, anterior, distal, and pos- exopod as long as basis, ischium, merus to- terior margins lined with plumose setae; is- gether, basal article armed with few small chium compressed, unarmed; merus twice as 42 JOURNAL OF CRUSTACEAN BIOLOGY, VOL. 20, NO. 1, 2000

Fig. 7. Ektonodiastylis robusta holotype subadult m. Telson and uropods. long as ischium, bearing 2 plumose setae dis- slightly shorter than merus, anterior margin tally; carpus 3 times as long as merus, pos- bearing 6 long stout annulate setae, increas- terior margin with 2 simple setae distally; ing in length distally; propodus one-half car- propodus one-half length of carpus, bearing pus length, bearing 1 stout annulate seta dis- 1 simple seta distally; dactyl one-half as long tally; dactyl shorter than propodus, with 1 as propodus, bearing 1 long and 4 simple se- slender simple seta marginally and 2 stout tae terminally; exopod slightly shorter than simple setae terminally; exopod longer than entire endopod, basal article bearing few basis and ischium together, basal article un- small simple setae, flagellum bearing 10 long, armed, flagellum bearing 12 setae (Fig. 6G). stout plumose setae (Fig. 6E). Pereiopod 5 basis as long as all other arti- Pereiopod 3 basis as long as all other articles together, distal margin bearing 3 plumose cles together, posterior and anterior margins setae; ischium unarmed; merus posterior mar- bearing plumose setae distally; ischium one- gin bearing 1 plumose, 1 simple, and 2 an- half merus length, posterior margin bearing nulate setae; carpus anterior margin having 3 sparsely plumose setae; merus posterior 4 annulate setae, 1 slender simple seta; prop- margin with 3 plumose and 4 annulate setae; odus one-half length of carpus, bearing 1 carpus one-half length of merus, anterior mar- stout annulate seta distally; dactyl shorter gin bearing 7 stout annulate setae, increas- than propodus, bearing 1 slender simple seta ing in length distally; propodus one-half marginally and 2 stout simple setae terminally length of carpus, with 1 stout annulate seta (Fig. 6H). distally; dactyl not as long as propodus, bear- One pleopod pair present, biramous, not ing 1 slender simple seta marginally, 2 stout fully developed (Fig. 6I). simple setae terminally; exopod longer than Telson 1.5 times length of pleonite 6, pre- basis and ischium together, basal article anal and postanal sections subequal; postanal armed with several plumose setae, flagellum section bearing 4 or 5 slender setae on each bearing 12 setae (Fig. 6F). side, 1 pair stout microplumose setae termi- Pereiopod 4 basis as long as next 3 arti- nally (Fig. 7). cles together, anterior and posterior margins Uropod peduncles subequal to telson, mar- bearing plumose setae distally; ischium 0.14 gins lined with fine hairlike setae, lateral mar- times basis length, bearing 2 simple setae; gin bearing 8 or 9 slender simple setae, me- merus 4 times ischium length, posterior mar- dial margin bearing 5 slender simple setae; gin having 4 annulate setae distally; carpus endopod two-thirds length of exopod, of 3 ar- GERKEN ET AL.: CONTUMACIOUS ARCTIC CUMACEA 43 ticles, all margins lined with fine hairlike se- ily Gynodiastylidae. The male antennule of tae, article 1 longest and bearing 3 stout se- Ektonodiastylis extends beyond the carapace tae medially, article 2 bearing 2 stout setae posterior margin and there is one pair of medially, article 1 with 2 stout setae termi- pleopods, whereas in male Gynodiastylidae nally, all stout setae having 1 subapical set- the antennule typically does not extend be- ule; exopod of 2 articles, article 1 one-third yond the carapace and pleopods are absent. length of article 2, bearing 1 slender seta dis- The females of Ektonodiastylis possess an ex- tally, article 2 lateral margin bearing 12 or opod on maxilliped 3, which is absent in fe- 13 sparsely plumose setae, with 2 very long male Gynodiastylidae. The telson, in both plumose setae terminally (Fig. 7). male and female, possesses distinct pre- and postanal sections, and the postanal section is DISCUSSION armed with robust setae, including large ter- The two species placed within the new minal setae; in contrast, Gynodiastylidae typ- genus are clearly separable based on several ically do not possess clear pre- and postanal characters. In E. nimia, the uropod exopod sections of the telson, and the telson is un- is at least twice the length of the uropod en- armed or armed with minute setae. dopod, while in E. robusta, the uropod exo- Ektonodiastylis seems clearly derivable pod is clearly longer than the endopod, but from Brachydiastylis. Brachydiastylis has two much less than twice the length of the endo- normal pairs of pleopods while Ektonodi- pod. The telson of E. nimia is shorter than the astylis has only a single pair. In addition, the uropod peduncles, whereas the telson of E. adult male of Ektonodiastylis shows the same robusta is distinctly longer than the uropod peculiarity in construction of the propodus peduncles. In E. nimia, the pseudorostral and dactyl on pereiopod 2 seen in Brachydi- lobes are nearly horizontal, whereas in E. ro- astylis, except that the dactyl is greatly re- busta the pseudorostral lobes are directed dis- duced. Otherwise, the two genera are nearly tinctly dorsally. The carapace of E. nimia is enough alike that Hansen, whose material did less deep, relative to the length, than the cara- not include males, can be excused for includ- pace of E. robusta. In addition, the subadult ing E. nimia in the same genus as B. resima. male of E. robusta is in excess of 5 mm in length, whereas adult individuals of E. nimia ACKNOWLEDGEMENTS are less than 4 mm in length. The National Science Foundation (Grant DEB15Ð The division of the Cumacea into its con- 21783) supported this work as part of the Partnerships to Enhance Expertise in Taxonomy (PEET) program. stituent families occurred at a time when few Thanks are due to the Zoological Museum in Copenhagen cumaceans were known from beyond the (ZMUC) and the Canadian Museum of Nature in Ottawa North Atlantic region. With the discovery of for access to their collections. One of us (SG) thanks Dr. the gynodiastylids in the southern hemi- Ole Tendahl, Anders Giessing, and Rikke Hansen for their sphere, Stebbing (1912) distinguished the hospitality while working in Denmark. new family Gynodiastylidae from the more LITERATURE CITED well-known Diastylidae on the basis of two Bate, S. 1856. On the British Diastylidae.—Annals and major characters: absence of pleopods in the Magazine of Natural History 17: 449Ð465. male and lack of an exopod on maxilliped 3 Day, J. 1980. South African Cumacea, Part 4: Families in the female in the Gynodiastylidae, whereas Gynodiastylidae and Diastylidae.—Annals of the South the Diastylidae possess two pairs of pleopods African Museum 82: 187Ð292. Hansen, H. 1920. Crustacea Malacostraca. 4. The Or- in the male and the female has an exopod on der Cumacea.—Danish Ingolf Expedition. Copenhagen maxilliped 3. Additional species have slightly 3(6): 1Ð86. blurred the boundary between these two fam- Lomakina, N. 1952. Cumacea of the seas of the ilies: in the genus Atlantistylis, the male bears USSR.—Opredeliteli po faune SSSR 66: 1–301. [In no pleopods but has an elongate antennule Russian.] Stebbing, T. R. R. 1912. The Sympoda, Part 6.—An- and an elaborate antenna, and in Paradiastylis nals of the South African Museum 10: 129Ð176. the female does not have an exopod on max- Schiotte, T. 1989. Marine Mollusca from J¿rgen Br¿n- illiped 3. Both genera are currently placed in lund Fjord, North Greenland, including the descrip- the Diastylidae. tion of Diaphana vedelsbyae n. sp. Meddelelser om Ektonodiastylis fits more completely the Grønlund.—Bioscience 28: 1–24. current definition of the cumacean family Di- RECEIVED: 7 December 1998. astylidae, rather than the closely related fam- ACCEPTED: 12 May 1999.