Amatiguakius forsberghi, a new genus and species from Alaska (marine Amphipoda: Epimeriidae)

9 Pages·1991·3.6 MB·English

. . .
PROC. BIOL. SOC. WASH.
104(2), 1991, pp. 279-287
AMATIGUAKIUS FORSBERGHI, A NEW GENUS AND SPECIES
FROM ALASKA (MARINE AMPHIPODA: EPIMERIIDAE)
C. O. Coleman and J. L. Barnard
Abstract.—T'hQ new genus and species, Amatiguakius forsberghi, was col-
lected in "pink coral" at 37 meters ofdepth from the Aleutian Islands. The
newgenusdiffersfrom othermembers ofAcanthonotozomellidae inthe prom-
inent rounded lateral carinae, and laterally ridged dorsal carinae; the presence
of2ridgesonthebroaddorsalcarinaeofpereonite 7 andpleonites; theextreme
multispinosity ofthe outer plate on maxilla 1; the strong setation on the inner
plateofmaxilla 1; and, onantenna2, thereductionoftheflagellumto 3 articles,
with antenna 2 shorter than antenna 1
Thenewtaxon,Amatiguakiusforsberghi, 3. Pereonite 1 with 1 dorsal carina,
to be described below, is the only species of coxae 2-3 divergent
its family found in the arctic-subarctic re- Acanthonotozomella
gion;allotherspeciesoccurintheantarctic- - Pereonite 1 with 2 dorsal carinae,
subantarctic region. coxae 2-3 similar Amatiguakius
The difficulty in classifying this species
was one ofthe reasonswe (Coleman & Bar- Amatiguakius, new genus
nard 1991) undertookarevision ofthegen- Diagnosis.—Body stout, with dorsal ca-
era in the old Epimeriidae and Iphimedi-
idae. Part of that revision included the rinae on pereon and metasome; pereonite 1
with 2 dorsal carinae, dorsal carinae later-
establishment of a new family, Acantho-
ally ridged, carinae on pereonite 7 and
notozomellidae, in which Amatiguakius is
nowplaced. Akeyto thegenera ofthe fam- metasomites wide, with 2 ridges; lateral ca-
rinae strongly produced and rounded; head
ilyispresentedbelowandreferencestothose
generamaybefoundinColeman&Barnard short,withstraightrostrum,lateralcephalic
lobes rounded; antenna 2 shorter than 1;
(1991).
peduncleofantenna 1 stout,withacutepro-
Acanthonotozomellidae cesses;labrumwithnarrownotch;mandible
Acanthonotozomellidae Coleman & Bar- with narrow incisor and setal row, but no
molar;laciniamobilispresentonbothman-
nard, 1991:257.
dibles; maxilla 1 with large innerplate, out-
erplatewithnumerousspiniformsetae, palp
Key to the Genera of
exceedingouterplate; setaeofmaxilla2 me-
Acanthonotozomellidae
dioapicallycomb-likesetulate; maxillipedal
1 Body processes bluntly rounded . palp slender, article 2 not produced; coxae
Acanthonotozomopsis 1 to 3 pointed, similarin shape and ridged;
- Bodyprocessesacuteorformedinto gnathopods simple, similar; bases ofpereo-
distinctly dorsal carinae 2 pods 5 to 7 broad, lobate ventrally; pereo-
2. Article 2 of maxillipedal palp me- pods 3-7 with small setae on medial and
dially produced Acanthonotozomoides lateralsurfaces;dactyliwithspiniform setae
.
- Article 2 of maxillipedal palp not on concave margin. Telson entire.
produced 3 Relationship.—T\\Qnewgenusbearssome
.
280 PROCEEDINGSOFTHEBIOLOGICALSOCIETY OFWASHINGTON
resemblance to the genus Paramphithoe The Acanthonotozomellidae differ from
Bruzelius, 1859, in the family Epimeriidae theAmathillopsidaeintheabsenceofamo-
(= Paramphithoidae, compare with Gur- lar, feeble gnathopods, and lack of inner
janova 1972), for example: two dorsal ca- lobes on the lower lip.
rinae on pereonite 1; strongly produced lat- The erection ofthe new genus was nec-
eralcarinae;acutecoxae 1 to3. Ontheother essarybecauseoftheremarkabledifferences
hand, the head of the new species lacks a from the known genera of Acanthonoto-
pointed lateral cephalic lobe; a mandibular zomellidae: the prominent rounded lateral
molar is absent; coxa 4 is not deeply exca- carinae; the laterally ridged dorsal carinae;
vate; the bases ofpereopods 5-7 are lobate the presence of2 ridges on the wide dorsal
ventrally;andthetelsonisshortanddistally carinae ofpereonite 7 andpleonites; anten-
rounded. na 2 with 3 flagellar articles; and antenna 2
On closer view, the new type species is shorter than antenna 1
similar to the "Acanthonotozoma-com-
plex" (compare Watling & Holman 1980).
Amatiguakiusforsberghi, new species
In particular, Acanthonotozomella Schel-
Figs. 1-5
lenberg, 1926, Acanthonotozomopsis Wat-
ling & Holman, 1980, and Acanthonoto- Etymology.—The generic name refers to
zomoides Schellenberg, 1931 seem to be the type locality. The species name is de-
closely related; these genera have been rel- rived from the collector ofthe material.
egated to a new family Acanthonotozomel- Holotype.-\5^1<iM 253545, female, 28
Udae by Coleman & Barnard (1991). The mm in length, with setose oostegites.
combination ofcharacters typical ofAcan- Type locality.—East side of Amatiguak
thonotozomella, Acanthonotozomopsis, Island, Aleutian Islands; 13 Jul 1958; col-
Acanthonotozomoides and Amatiguakius lected by Eric D. Forsbergh (Inter-Ameri-
thatdiffersfromgenerainthe Iphimediidae can Tropical Tuna Commission) "on pink
is as follows: gnathopods simple, similar coral, caught on . . . line" [fishing line?];
in shape and setation (versus differences in depth, 20 fathoms.
lengths, setation and the typical euchela Description.—Body: Stout, pereonitesand
foundinalltrueiphimediids);andsetalrak- pleoniteswithdorsalcarinae,laterallyridged
errowpresent(absentinIphimediidae). The as in Fig. lb. Lateral carinae on pereonites
genera mentioned above bear in common: strongly projecting as in Fig. la. Pereonite
body dorsally armamented; lateral carinae 1 with 2 dorsal carinae, anterior carina
present; labrum narrowly notched; mandi- shorter, pointing anteriorly, posterior cari-
bles with raker row, molar absent; lobes of naslightlybentposteriorly, similarinshape
maxilla 2 with similar setae; short and and length to carinae of succeeding seg-
rounded telson; and dactyli at least of ments; dorsal carinae of pereonite 7 and
gnathopods with spiniform setae on con- metasome with 2 ridges laterally and wider
cave margin. Acanthonotozomella barnardi than preceding segments (seen from lateral
Watling & Holman, 1980 and the new spe- view); metasomal epimera ridged as in Fig.
cies bear setae in the hypopharyngeal gap. lb,withacuteprocessposterolateromargin-
The rostra ofAcanthonotozomoides subli- ally; urosomite 1 longest, with middorsal
toralis, Acanthonotozomella barnardi, acute process, short posteromarginal pro-
Acanthonotozomellaalataandthenewspe- cess on urosomite 2, urosomite 3 excavate
cies have raised lateral edges. posteromarginally.
The Acanthonotozomellidae differ from Head (Fig. Ic, d): Short (about as long as
the monotypic Acanthonotozomatidae in pereonites 1-2 together, partially hidden
the presence ofmandibular rakers. undercoxa withweakposteriorelevation
1;
VOLUME 104, NUMBER 2 281
.^-s?^^5^
^^
d
mm
Fig. 1. a-d. Amatiguakiusforsberghi n. sp., holotype, 28 in length, a, dorsal view, b, lateral view, c,
headseenfromdorsal, d, rightlateral side ofhead.
and dorsal ridge; horizontal rostrum with ally; article 2 shorter, with acute process;
raised lateral edges, truncate anteriorly in article 3 shortest; two small rounded pro-
lateralview; roundedepistomal processbe- jections medially and proximally to flagel-
tween antennae 2, round lateral bulges, but lum, smaller one with two setae distally
no ommatidia or pigmentation (blind?); (vestigial accessory flagellum?); flagellum
ventrolateral lobes rounded, slightly bent with 1 1 articles, each with conspicuous
laterally. group oflong aesthetascs and setae apically
Antenna 1 (Fig. 2a): Short, peduncular (Fig. 2c). Antenna2(Fig. 2b).—Shorterthan
article 1 stout, with pointed process later- antenna 1 (about 55%); peduncular articles
282 PROCEEDINGSOFTHEBIOLOGICALSOCIETY OFWASHINGTON
0,1mm
mm
Fig. 2. a-1. Amatiguakiusforsberghin. sp., holotype, 28 in length, a, antenna 1, b, antenna2, c, detail
ofantenna 1, d, labrum, e, right mandible, f, distal part ofleft mandible, g, maxilla 1, setae on outer plate
omitted, dottedline indicates length ofspiniform setae, h, palp ofmaxilla 1, i, spiniform setae on outerplate
ofmaxilla 1, place ofinsertion ofhair-like setae is shown.
1-3 short, distally serrate with short setae, Labrum (Fig. 2d): Ventral margin round-
articles4-5 subequalinlength,coveredwith ed, medially notched,
groupsofshortsetae; flagellum 3-articulate, Mandibles (Fig. 2e, f): Slender, incisors
article 1 longest, with 3 groups ofsetae. narrow,weaklytoothed;rightmandiblewith
VOLUME 104, NUMBER2 283
mm
Fig. 3. a-e. Amatiguakiusforsberghi n. sp., holotype, 28 in length, a, maxilla 2, dotted line indicates
lengthsofsetae, detailshowsapicalregion ofinnerandouterplate, b, innerplateofmaxilliped, seen from oral
side, c, lowerlip, d, maxilliped, seen from ventral side, e, pereopod 1, setation ofmerus to dactylus on detail.
slender lacinia mobilis, left lacinia broader 3 slightly bent laterally, densely setose ven-
(Fig. 21); raker setal row on thin projecting trally.
lamella, molarabsent; palp 3-articulate, ar- Lower lip (Fig. 3c): Broad; apices round-
ticle 2 longest, with setae ventrally, article ed, bent medially, covered with hair-like
284 PROCEEDINGSOFTHEBIOLOGICALSOCIETY OFWASHINGTON
mm
Fig. 4. a-e. Amatiguakiusforsberghin. sp., holotype, 28 inlength, a, pereopod2, setationofmerusto
dactylus shown ondetail, b, pereopod 3, c, coxa ofpereopod4, d, pereopod 5, e, pereopod4.
setae apically; hypopharyngeal gap with se- tively large, with 12 setulated setae medio-
tae medially; mandibular processes broad, marginally; outer plate broad, densely cov-
with hair-like setae posteriorly. ered with hair-like scales apically, with
Maxilla 1 (Fig. 2g-i): Inner plate rela- numerous (29?) spine-like setae, each ser-
VOLUME 104, NUMBER 2 285
0,5 mm
mm
Fig. 5. a-g. Amatiguakiusforsberghi n. sp., holotype, 28 in length, a, pereopod 6, b, pereopod 7, c,
pleopod 1, detail shows couplinghooks, d, uropod 1, e, uropod 2, f, uropod 3, g, telson.
rate medioapically (Fig. 2i); slender palp tationespeciallyonouterplate,allsetaedis-
2-articulate, exceedingouterplate, stout se- tomedial comb-like setulate (except short
tae apically, slender setae laterally. medial straw-like scales on face of inner
Maxilla2(Fig. 3a):Outerplatewiderthan plate),
inner plate, equal in length, very dense se- Maxilliped (Fig. 3b, d): Inner plate elon-
—
286 PROCEEDINGSOFTHEBIOLOGICALSOCIETYOFWASHINGTON
gate, short spiniform setae on distomedial ly;merusandcarpusstout,expandeddistally
angle, smoothsetaeonmedialmargin, scales into posterodistal processes, spiniform se-
on oral face; outer plate broad, with spini- tae anteromarginally; propodus slightly
form setae apically, setae mediomarginally rounded posteriorly, spiniform setae an-
and on ventral face; palp relatively slender, teromarginally, subequalinlengthto merus
3-articulate on right, seemingly 4-articulate plus carpus; dactylus with spiniform setae
on left. anteriorly.
Gnathopod 1 (Fig. 3e): Coxa apically Pereopod 6 (Fig. 5a): Coxa subquadrate,
pointed, sinuoid anteriorly, ridged on lat- with similar rounded process as on coxa 5;
eral face, additional but weaker ridge near basis slightly longer than that ofpereopod
posterior margin, short setae posteromar- 5; ischium to dactylus as for pereopod 5.
ginally; basis slender; ischium short; merus Pereopod 7 (Fig. 5b): Coxa small, ridged;
short with group of setae apically; carpus basis similar to that of pereopod 6, but
slightly expanded distally, densely covered slightly wider; ischium to dactylus as for
with setae posteriorly and apically; propo- pereopods 5 and 6.
dus shorterthan carpus (82%), with medial Pleopod 1 (Fig. 5c): Pedunclerectangular;
and posterior setation, spiniform setae dis- rami subequal; two coupling hooks as in
toventrally; dactylus with spiniform setae detail ofFig. 5c.
posteromarginally. Uropod 1 (Fig. 5d): Peduncle elongate,
Gnathopod 2 (Fig. 4a): Coxa similar to with numerous spiniform setae on both
coxa 1; basis, ischium and merus similarto margins; rami shorter (0.8) than peduncle,
gnathopod 1; carpus only slightly expanded outer ramus slightly shorter than inner ra-
distally, with posterior setation; propodus mus, rami with rows ofspiniform setae on
setose medially and posteriorly; dactylus both margins.
spiniform, with slender setae posteriorly. Uropod2 (Fig. 5e): Ramisimilartothose
Pereopods 3-7: Lateral and medial faces ofuropod 1 but as long as peduncle.
ofarticles 2-7 covered with short setae. Uropod 3 (Fig. 5f): Peduncle short, with
Pereopod 3 (Fig. 4b): Coxa longer but dorsal process apically; rami lanceolate,
similarin shapeto precedingcoxae, butnot about 2.5 times as long as peduncle, outer
as excavate anteriorly, basis longer than is- ramus slightly shortened, both rami with
chium and merus; merus and carpus ex- spiniform setae on both margins.
pandeddistally,withprocessanterodistally, Telson (Fig. 5g): Distally rounded; two
with spiniform setae posteromarginally; plumose setae on each side.
propodusslender,withspiniformsetaepos- Discussion. —The asymmetrical devel-
teromarginally; dactylus curved with spi- opment of the maxillipedal palp of the
niform setae and claw. unique specimen ofthe newspecies maybe
Pereopod4(Fig. 4c,e):Coxaridged,elon- due to loss and regeneration of the right
gated, sinuoid anteriorly and posterodistal- palp. It isnotcleariftherounded processes
ly; basis to dactylus similar to those ofper- proximal to the flagellum ofantenna 1 may
eopod 3. be distinguished as remnants of an acces-
Pereopods 5-7: Similar except for coxae. sory flagellum.
Pereopod 5 (Fig. 4d): Coxa ridged, wider
thanlong,roundedanteriorly,withrounded Literature Cited
processoncoxalfaceposteroventrally;basis
broad,longerthanmeruspluscarpus,ridged, Bruzelius, R. M. 1859. Bidrag till kannedomen om
skandinaviens Amphipoda Gammaridea.
posteromarginal excavation bounded dor-
Kongliga Svenska Vetenskaps-Akademiens
sally by triangular projection, lobate ven- Handlingar, new series, 3:1-104.
trally, covering ischium and merus partial- Coleman, C. O., &J. L. Barnard. 1991. Revisionof
VOLUME 104, NUMBER 2 287
Iphimediidaeandsimilarfamilies(Amphipoda: Watling, L., & H. Holman. 1980. New Amphipoda
Gammaridea).—Proceedings of the Biological fromtheSouthernOcean,withpartialrevisions
SocietyofWashington 104:253-268. of the Acanthonotozomatidae and Paramphi-
Gurjanova, E. 1972. Novye vidy bokoplavov (Am- thoidae.—ProceedingsoftheBiologicalSociety
phipoda,Gammaridea)izseverozapadnoichas- ofWashington 93:609-654.
ti Tikhogo Okeana.—Akademiia Nauk SSSR,
TrudyZoologicheskogo Instituta 52:129-200. (COC) Fachbereich 7, Zoomorphologie,
Schellenberg, A. 1926. Die Gammariden der
Universitat Oldenburg, Postfach 2503,
deutschen Siidpolar-Expedition 1901-1903.—
Deutsche Siidpolar-Expedition 18:235^14. D-2900, Oldenburg, F.R.G.; (JLB) Depart-
. 1931. GammaridenundCaprellidendesMa- ment of Invertebrate Zoology, National
gellangebietes, Siidgeorgiens und der Westant- Museum of Natural History, Smithsonian
arktis.—FurtherZoologicalResultsoftheSwed- Institution, Washington, D.C. 20560.
ishAntarcticExpedition 1901-1903 2(6):1-290.