Redescription of Maxilliphimedia longipes (Walker, 1906) (Crustacea: Amphipoda: Iphimediidae) from the Antarctic Peninsula

8 Pages·1991·0.41 MB·English

by  C. O. Coleman

30 September 1991
Memoirs ofthe Museum ofVictoria 52(2): 291-298 (1991) ISSN 0814-1827
https://doi.org/10.24199/j.mmv.1991.52.06
REDESCRIPTION OF MAXILLIPHIMEDIA LONGIPES(WALKER, 1906)
(CRUSTACEA: AMPHIPODA: IPHIMEDIIDAE) FROM THE ANTARCTIC PENINSULA
By Charles Oliver Coleman1 and J. L. Barnard2
'Fachbereich 7, Zoomorphologie, Universitat Oldenburg, Postfach 2503, D-2900, Oldenburg, Germany
-NHB-163, Department ofInvertebrate Zoology, Smithsonian Institution, Washington, DC, 20560, USA
Abstract
Coleman, CO. and Barnard, J.L., 1991. Redcscription of Maxilliphimedia longipes
(Walker, 1906) (Crustacea: Amphipoda: Iphimediidae) from the Antarctic Peninsula.
Memoirsofthe Museum ofVictoria 52: 291-298.
Newfiguresanddescriptionofthisspeciesarcpresented.Thegenus isthemostprimitive
in the Iphimediidae and the characters involved in this decision are listed.
Introduction Iphimedia longipesWalker, 1906a: 151-152: 1907:
Only three previous records of Maxilliphi- 29-M3a0x,ilplii.p9hifmige.di1a7. longipes.—K.H. Barnard, 1930:
media longipes have been published. We add 355-356, fig. 28.—Watlingand Holman, 1981a: 204,
here the fourth and redescribe and refigure the fig. 14.
species in its entirety.
Material examined. Antarctic Peninsula (6()°49.9'S,
Maxilliphimedia K.H. Barnard V5I5/"23,8.s2t'nW1)2,/038972,-f3i8sh4ermy,boRtVtoPmoltraarwslt,erUnSCNruMis2e5A37N0T7
Maxilliphimedia K.H. Barnard, 1930: 355 (type (male "a", 32 mm; female "b", 43 mm).
species, Iphimedia longipes Walker, 1906, monot-
ypy).—Watling and Holman, 1981: 202. Description. Body(Fig. 1b,2b): head longerthan
Diagnosis. Body with dorsal teeth. Antenna 1: pceeprheaolniictelo1,beropsrtorduumcesdt,ronpgoliyntdeedt,leoxceudl,arlatleorbael
peduncular article 2 shorter than 1. Bundle of rounded, with ventral notch; eyes circular, pig-
mouthparts not projecting conically. Labrum
mentary masses irregularly arranged.
bilobed; it and epistome very broad. Man- Pereon slender in male, widened in female,
dibular incisor broad, minutely serrate; raker coxalplatesprotrudingsomewhat laterally(seen
rowabsent;molarabsent. Lowerlip:, innerlobes fromdorsalside);pereonite2shortest,pereonite
absent. Maxilla 1: palp 2-articulate, article 2 7 longest, posteromarginally with pairofstrong,
ernolwargoefd.setMaaex.ilMlaaxi2l:liipnendesr:pliantneerwitphlaotuet mfaucciahl ealnodng2atweidthteseithmidliarrectteeetdh;posetpeirmioerrloyn; p1leroonuitnedsed1
shorter and narrower than outer plate, latter ventrally, ridged laterally, posterolateral margin
elongate: palp article 2 weakly produced api- acutely or subacutely produced; epimeron 2
comedially, article 4 vestigial. Coxae ordinary: ridged laterally, posteroventral corner pointed;
1-3extendingsubequally, coxa 4slightly longer; pleonite 3 without dorsal armament, postero-
coxa 4 bicuspidate. Gnathopods oflinear form, lateral margin drawn out as conspicuous cusp;
minutely chelate. Telson deeply incised or dis- no lateral ridge, posteroventral corner acute;
tinctly cleft. urosomite as long as urosomites 2 and 3 com-
1
Remarks. This genus is characterized by the bined,anteriorlywith hump, middorsallysome-
large article 2 of the palp on maxilla 1, and what depressed; urosomite 3 excavate pos-
thereby differs from Iphimedia and Iphi- teriorly, with weak medial depression.
mediella. Antenna 1 (Fig.2c):pedunculararticle 1 stout,
with long pointed terminal process, articles 2
Species. Monotypic. M. longipes (Walker, 1906, and 3 slender; accessory flagellum uniarticulatc
1907) (K.H. Barnard, 1930) (Watling and Hol- (secdetail in Fig. 2c); flagellararticles(37)stout,
man, 1981), marine, Antarctica, 183-769 m. with longaesthetascsandgroupofshort setae(as
in detail ofFig. 2c). Antenna 2 (Fig. 2a): pedun-
Maxilliphimedia longipes (Walker, 1906) culararticles 1 and 2withacuteprocesses,gland
Figures 1-5 cone produced, article 3 widened distally, ar-
291
292 C. O. COLEMAN AND J. L. BARNARD
K?
region;'e',Mlaefftlimpanhdiirbnleed;iaf,lloanbgirpuems;,mg,almea,xi3l2lamm2..a,lowerlip;b,lateralview;c,mandibularpvalpv-'d'rieghutmcisor
MAX1LL1PH1MEDIA LONGIPESFROM THE ANTARCTIC PENINSULA 293
mm
1
Figure 2. Maxill,,iph,imedi,.a liongi•pes, malei„, 3-n2 mmrmr., aa, aannttepnnnanaz,2bd, duourisbaali viie=w:, c,, antenna l;d, maxilla 1.
COLEMAN AND BARNARD
294 C. O. J. L.
Figure 3. Maxilliphimedia longipes, male, 32 mm. a, maxilliped, ventral side; b, chela of gnathopod 1; c,
gnathopod 1; d, inner plate ofmaxilliped, dorsal view; e, gnathopod 2.
MAXILLIPHIMEDIA LONGIPESFROM THE ANTARCTIC PENINSULA 295
Figure 4. Maxilliphimedia longipes, male, 32 mm. a, percopod 3; b, pereopod 4; c, pereopod 5; d, telson; e,
pereopod 6.
296 C. O. COLEMAN AND J. L. BARNARD
Figure5.Maxilliphimedialongipes,male,32mm.a,pereopod7;b,pleopod 1;c,uropod 1;d,uropod2;e,uropod
tides 4 and 5 elongate, with groups of short Maxilla 1 (Fig. 2d): inner plate with smooth
setae; flagellar (33) articles with groups ofsetae setaemediallyandapically;outerplatetruncate,
distally. with 14 smooth spiniform setae apically; palp
Mouthparts bulky, not conically projecting Particulate, article 2 elongate,ovallyexpanded,
ventrally. Labrum (Fig. 10 broadly lobate, with row ofshort stout setae and rowofslender
medially notched; epistome slightly produced setae extending along medial margin. Maxil-
dorsallyfrom labralborder, acutedorsal margin liped (Fig. 3a, d): inner plate with long smooth
fused with acute process between second setae mediomarginally and shorter setae disto-
antennae. Mandible (Fig. lc-d) broad, medially marginally; outer plate broadened, ventral face
excavate; incisor minutely serrate, right incisor and margins covered with short setae; palp 4-
eonvterolnapbpoitnhgmlaenftd;ibslleensd;eprallapci3n-iarateicmuolbaitle,isarptriecsl-e aslritgihctullyatpe,roadrutcicelde d1isetxopmeadnidaeld,coarrnteirc,lear2ticwlieth3
2 longest, with group ofsetae distally, article 3 slender, article 4 vestigial.
curved laterally, with ventral row of setae and Onlycoxa4(ofcoxae 1-4)weaklyacuminate;
some longer terminal setae. Lower lip (Fig la) coxa 1 broadened distally, truncate apically;
truncate apically, mandibularprocess subacute. coxa 2 slightly tapering distally, truncate
MAXILUPHIMED1A LONGIPES FROM THE ANTARCTIC PENINSULA 297
apically: coxa 3 slightly curved posteriorly, bordered with short spine-like setae. Uropod 3
distally truncate; coxa 4 rounded anteriorly, (Fig. 5e): peduncle short, lateral margin turned
pointedventrally.posteriormargindrawnoutas upwards and pointed distally; outer ramus
subacute cusp; coxa 5 widerthan long, rounded slightly shorter than inner; rami bordered with
anteriorly, pointed posteriorly: coxa 6 shorter spiniform setae. Telson (Fig. 4d) notched
than wide, rounded anteriorly, subacute pro- slightly more than one-third, lateral margins
cessed posteriorly; coxa 7 smallest, acutely turned dorsalwards. 3 plumose setae on each
pointed posteriorly. Gill: ofcoxa 2 not reaching side.
beyondapexofbasis;ofcoxa3 sack-like,shorter
thanbasis;ofcoxa4sack-like,shorterthanbasis; Remarks. The material redescribed herein
ofcoxae 5-6 sack-like. matches well with the descriptions of Walker
Gnathopod 1 (Fig. 3b. c): basis dilated proxi- (1906. 1907) and the additions given by K.H.
mally: ischiumandmeruswithgroupssetaepos- Barnard (1930). The only characters differing
teriorly; carpus and propodus elongate, length from formerdescriptionsare: (a)theupperlip is
ratio = 31:37, propodus and dactylus forming notched rather symmetrically (different from
chela. Gnathopod 2 (Fig. e): ischium slightly conditionsdescribed in thegenericdiagnosisby
expandeddistally,somewhat longerthanmerus; K.H. Barnard (1930); (b)thebasisofgnathopod
merus broadened distally: groups of long setae 1 is less setose compared to the specimen
posteromarginally; carpus elongate, weakly described by Watling and Holman (1981). A
expanded distally. groups of setae postero- slight variability was observed in the posterior
marginally; propoduselongate, ratiotocarpus= margins of the epimeral plates and coxae 5-7;
51:46. forming chela together with dactylus; theyareacutely pointed in some specimens, but
longsetaeposteromarginallyand onlateral face. rather blunt in others. The depth of the mid-
Pereopod 3 (Fig. 4a): basis subequal in length to dorsal depression on pleonite 1 is variable.
coxa, slender; ischium smallest: merus slightly Maxilliphimedia undoubtedly is the most
expanded distally. drawn out as acute process; primitivegenus in the Iphimediidae (as defined
carpusshorterthanmerusandpropodus.weakly and strongly restricted by Coleman and
widened distally; propodus quite long; dactylus Barnard, 1991. but seethephylogeneticanalysis
slender, with short spiniform setae anteriorly; ofWatlingand Thurston, 1989). Apart from the
merus to propodus with groups of short setae plesiomorphic state of the transverse cutting
posteromarginally. Pereopod 4 (Fig. 4b): plane ofthe incisors there are some characters
ischium to dactylus as in pereopod 3. Pereopod which are unique to Maxilliphimedia in the
5 (Fig. 4c): basis widened, with posterior cusp, Iphimediidae, but can be found also in the
overlappingcoxa proximally: lateral face with 2 Stilipedidae: (1) mouthparts not arranged in a
ridges; ischium short, partially hidden by basis; conicalbundle,butbulky,coveredbylargeouter
meruswith poslerodistal process:carpusweakly plateofthemaxilliped;(2)outerplateofmaxilla
expanded distally; propodus slender, subequal 1 with smooth spiniform setae apically; palp
in length to basis; ischium to propodus with expanded distally and bordered with 2 rows of
setae anteromarginally: dactylus as in pereopod setae: (3) maxilla 2 inner and outer plates
2. Pereopod 6 (Fig. 4e): basis widerthan in pre- rounded distally, relatively broad; (4) maxilli-
cedingpereopod,overlappingcoxaposteroprox- pcdal outer platewith reduced setation margin-
imally. acutely produced posterodistally, lateral ally,but ventralfacecoveredwithshortsetae;(5)
faces with 2 ridges; ischium to propodus as for coxa 1 expanded distally(versustaperingcoxa 1
pereopod 5. but longer. Pereopod 7 (Fig. 5a): in all other Iphimediidae); (6) pereopods 5 to 7
basislarger than in pereopods 5 and 6, broadest increasing in length; (7) pereopod 7 reaching
proximally, with acute posterodistal process beyond uropods (compare with the stilipedid
directed ventrally, 2 ridges on lateral face; Bathvpanoploea schellenbergi Holman and
ischium todactylusasdescribed forpereopod 5, Watling, 1983).
but somewhat longer. Two other synapomorphic features clearly
Pleopods(Fig. 5b)normal. Uropod 1 (Fig. 5c): designate Maxilliphimedia longipes as an iphi-
pedunclelonger(107%)than innerramus, outer mediid: (1) gnathopods both chelate, with the
ramus shorter than inner (82%); margins of typical pattern oflength, shapeand setation; (2)
peduncle and rami bordered with short spine- pairedteethpresentonpereonite7andpleonites
like setae. Uropod 2 (Fig. 5d): peduncle shorter 1-2. It cannot yet be decided ifthe characters
(70%) than inner ramus; outer ramus shorter shared by the primitive Stilipedidae and the
than inner(70%); marginsofpeduncleand rami moreadvanced Maxilliphimediaareconvergent
298 C. O. COUiMAN AND J. L. BARNARD
formations due to a similar mode of life or a Walker, A.O., 1906. Preliminary descriptions ofnew
result ofphylogenetic vicinity. species of Amphipoda from the 'Discovery'
Ditiys)t;rMibcuMtiuorn.dCooSuolumnadn,I3s7l9anmd,;1B8r0anmsfi(etlydpeSltoraciatl,- WalkeMArna,tgaarzcAit.iOnc.eoEf1x9Np0ea7dt.iutriaColrnuH,sistta1oc9re0ya2,.-s1e9Ir0IiI4e..s 7A,Amn1pn8ha:il1ps3o-da1an8..d
265-769 m; Antarctic Peninsula, 384-392 m. National Antarctic Expedition, British Museum
(NaturalHistory) 3: 1-39, 13 pis.
References Watling, L., and Holman, H., 1981. Additional
acanthonotozomatid, paramphithoid, and stcgo-
Barnard, K.H., 1930. Amphipoda. British Antarctic cephalid Amphipoda from the Southern Ocean.
("TerraNova")Expedition, 1910. NaturalHistory ProceedingsoftheBiologicalSocietyofWashing-
ColeRmeapno,rtsC.O.ZooalnodgyBa8r:na3r0d7,-4J5.4L.,,61399f0i.gs.Revision of Watlitnong,,9L4.:an1d81T-h2u2r7s,to2n7,fMigs,. 1989. Antarctica asan
[phimediidae (Amphipoda, Gammaridea). I'ro- evolutionaryincubator:evidencefrom thecladis-
ceedingsoftheBiologicalSocietyofWashingtonin tiebiogeographyoftheamphipod familyIphime-
Ilolmpraens,s.II. and Watling, L„ 1983. A revision ofthe dtiioindaoc.ftIhn:eCAnrtaamrcc,tiJc.Ab.io(tead..)G,eOorlioggiincsalaSnodcieevtoyluo-f
S53t,ilipedidae (Amphipoda). Crustaceana 44: 27- America Special Publications 47: 297-313.