Georg Ossian Sars.

An account of the Crustacea of Norway: with short descriptions and ..., Volume 2 online

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the ]pleopoda. It differs from Cryptocope arctka Hansen, which it somewhat resembles
in the form of the body, in the rami of the pleopoda being quite smooth, whereas
in the last-named species, according to Dr. Hansen, they are tipped with
smafi bristles.

Occurrence. — 1 first discovered this form in the Christiania Fjord
at a depth of about 30 fathoms, and have subsequently found it occasionally in
other places also, both on the south and west coasts of Norway. It has not
been recorded by any other author.

Gen. 7. Haplt)<30pe, G. O. Sars, 1880.

Generic Characters. — 9« Body slender a«d elongated, resembling, as regards
its outward appearance, some species of the genus Leptognathia. Metasome rather

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iiarrow, sublinear, witb aU the segments v^ll defined. Eyes wanting. Superior
antenn^B (in female) distinctly ^-articulate. MandiUes weU developed, and r^em-
bling in structure those in the geftus Typhlokinaisy, the molar expansion being
rather strong, cylindric, apd armed at the tip with dentiform tubercles^.. Oheii-
peds comparatively small, with the hand scarcely dilated. The first 3 pairs of
pereiopoda of similar structure, and more slender than the 3 posterior. Pleopoda
(in female) imperfectly developed, forming simple oval lamellae, without a trace
of setffi. Uropoda rather slender, biramous, rami unequal, biarticulate. Incuba-
tory pouch normal.

Remarks, — The most prominent character of this genus is the simple
structure of the pleopoda in the female, and it is indeed from this character,
that the generic name has been derived. In outward appearance, as also in the
structure of the several appendages, it exhibits a close resemblance to the genus
Leptognaihia ; but the structure of the mandibles is very different, and agrees
much more closely with that found in the genus Typhlotanais, The genus con-
tains as yet but a single species.

Haploeope angusta, G. Q. Sars.

(PI. XV. fig. 2).
Haploeope angusta, G. 0. Sars, 1. c. p. 51.

Specific Characters. — 9« Body extremely slender and narrow, being
fully 10 times as long as it is broad. Cephalosome rather small, slightly nar-
rowed anteriorly, front truncated. 1st free segment of mesosome but little smaller
than the next succeeding ones and somewhat dilated in front, last segment
the smallest. Metasome about the length of the last 2 segments of mesosome
combined, and nearly of uniform breadth throughout, terminal segment of medium
size, and angularly produced in the middle. Superior antennae somewhat shorter
than the cephalosome, basal joint only attaining the length of the 2 succeeding
joints combined, last joint naiTOw, conic. Chelipeds rather small, hand about the
length of the cai*pus, fingers shorter than the palm. 1st pair of pereiopoda
scarcely longer than the 2 succeeding pairs; the 3 posterior pairs a little stronger,
and having the outer joints spinous. Uropoda about half the length of the me-
tasome, inner ramus rather elongated, outer scarcely more than half as long and
much naiTOwer. Length 1.70 mm.

Remarks, — As stated above, this is the only species as yet known of
the genus, and may easily be recognized by its slender, narrow body, and the
simple, laiuelliform pleopoda.

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Occurrence, — I have met with this form occasionally in 3 widely remote
localities, viz., in Eidsfjord, west of Listerland, at Bekkervig, on the west coast
of Norway, and at Apelvser in NamdaJ. In all 3 places it occurred in rather
small numbers together with other Tanaids, in depths ranging from 100 to 150 fathoms.

Gen. 8. StTOngylUPa, G. O. Sars.

Oeneric Characters. — Body more or less elongated, subcylindric in form,
with rather hard integuments. Cephalosome comparatively large, narrowly trun-
cated in front. Metasome of quite an unusual size, cylindric, slightly widening
behind, and composed of 6 well-defined segments, the last of which is very large,
cupuliform. Eyes wanting. Superior antennae in female rather strong, 4-articu-
late. Mandibles well developed, cutting part strongly incurved, and divided into
a few short teeth, molar expansion large, laminar, minutely dentated at the tip.
Chelipeds strongly built, with the hand rather large. Pereiopoda comparatively
slender and elongated, with the dactylus narrow, setiform. Pleopoda in female
wholly absent. Uropoda very small, though distinctly biramous.

Remarks, — The present genus is prominently distinguished by the
peculiar appearance, in the female, of the metasome, which is of quite an unusual
size, and has the segments perfectly cylindric, without a trace of epimera. Nor
is the slightest rudiment of pleopoda to be detected in the female, whereas in
the male they seem to occur in the normal condition. In addition to the type
species described below, Messrs. Norman & Stebbing have recorded another species,
S. arctophylair, from the Porcupine Expedition.

Strongylura eylindrata, G. 0. Sars.

(PI. XVI, % 1).
strongylura eylindrata, G. O. Sars, 1. c. p. 63.

Specific Character's. — 9- Body rather slender and narrow, about 9 times
as long as it is broad, and slightly narrowed in the middle, with the segments
marked ofif by conspicuous constrictions. Cephah)some comparatively large, almost
equalling in length the first 3 segments of mesosome combined, oblong oval in
form, and slightly narrowed in front. 1st free segment of mesosome much shorter
than the others. Metasome occupying rather more than Va ^ ^he length of the

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body, or equalling about the first 6 segments of mesosome combined, slightly
widening behind, terminal segment large, oblong oval and very smooth, tip obtusely
rounded. Superior antennae almost attaining the length of the cephalosome,
basal joint about the length of the other 3 combined, terminal joint comparatively
short and obtusely blunted at the tip. Chelipeds rather strong, hand oblong
OTal and longer than the carpus, fingers shorter than the palm, the immovable one
minutely serrulate inside. The 3 posterior pairs of pereiopoda considerably more
strongly built than the 3 anterior ones, and having the outer joints armed with
ciliated spines, basal joint remarkably constricted at the base. Uropoda very short,
inner ramus conical, biarticulate, and tipped by long diverging Setae, outer ramus
extremely minute, tuberculiform, though well defined from the basal part. Length
2.85 mm.

Remarks. — From S, arctophylax of Norman & Stebbing, the Norwegian
species may be at once distinguished by its much more elongated body and the com-
paratively larger size of the metasome. A few specimens, however, are of con-
siderably shorter form, but as in all of these there are distinct traces of pleo-
poda, they are, I believe, of the male sex, though probably not yet sexually matui*e.

Occurrence. — I have found this peculiar Tanaid in several places, both
on the south and west coasts of Norway, in depths ranging from 60 to 200 fa-
thoms. It extends northwards to Selsovig, situated just within the polar circle.

Gen. 9. AnaPtlirUPa, G. O. Sars, 1880.

Oeneric Characters. — Body elongated, subdepressed, with rather thin,
semipellucid integuments. Cephalosome comparatively short and obtusely trun-
cated in front. Metasome in female very poorly developed, nan*ower than the
mesosome, and without a trace of segmentation ; that in male, however, of quite
normal appearance, being divided into 6. well-defined segments. Eyes wanting.
Superior antennae in female 4-articulate, in male but slightly different, though
composed of 5 articulations. Mandibles extremely small and rudimentary, cutting
edge simple, molar expansion wanting. Chelipeds comparatively small, with the
basal part of a somewhat unusual structure, being oval, tumid, and divided into
2 distinct segments, hand rather small, with the palm unusually short. The 3
anterior pairs of pereiopoila rather slender and nearly equal, the 3 posterior
pairs rather diflferent, and considerably more strongly built. Pleoj)oda in female

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wboUy abseni, in male normally deyeloped. Uropoda hnperfee% Iniramous, tke
osier ranws not being defined from the basal part.

Bemarlcs, — In this genus also, the structure of the metasome in the
female jiolds the most conspicuous distinctive character; but whereas in the
genus SirofUffylura this division is of quite an unusual size, it is in the present
gMius more reduced in size than in any hitherto known Tanaid. In the male,
however, this part exhibits quite a normal appearance. The structure of the
chebpeds is likewise somewhat peculiar and differs, among other things, from
that of all other Tanaids in the form of the basal part The oral parts, and
especially the mandibles, exhibit a similar rudimentary condition to that found
in the genus Tanaopsis. Besides the typical species described below, the Austra-
lian form Paratanais linearis Haswell, according to the opinion of the Rev. Mr,
Stebbing, should more properly be referred to this genus.

Anarthrura simplex, G. 0. Sars.

(PI. XVI, fig. 2).
Anarthrura simplex^ G. O. Sara, 1. c. p. 54.

Specific Characters, — Body in female about 8 times as long as it is
broad, in male somewhat shorter, segments marked off by rather deep constrictions.
Cephalosome distinctly depressed, scarcely longer than it is broad, and obtusely
truncated in front. 1st and last segments of mesosome shorter than the others,
and almost quadrate in outline. Metasome in female scarcely longer than the
penultimate segment of mesosome, narrow cylindric, or very slightly depressed,
and somewhat constricted in the middle, tip obtusely angular; that in male nearly
twice as large, and of altogether normal appearance. Superior antennae in female
about the length of the cephalosome, basal joint but little longer than the 2
succeeding ones combined, terminal joint narrow, conical in form. Chelipeds with
the basal part occupying half their length, and having its first segment much
larger than the 2nd, hand longer than the carpus, but rather feeble, with the
palm unusually shoii;, fingers narrow ai>d not perfectly contiguous when shut, the
movable one slightly serrated outside, the immovable one nearly straight and termin-
ating in a lanceolate point. The 3 anterior pairs of pereiopoda exactly alike, having
the propodal joint tapering conically, and the dactylus long and setiform; the 3
posterior pairs more strongly built, with the basal joint rather tumefied, and
the dactylus quite short. Uropoda generally turned obliquely outwards, inner
ramus well defined, Particulate, outer represented by a conical, setiferous pro-
jection of the basal part. Length of female 2.36 mm.

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Bemarks. — This peculiar form may at once be distinguished from our
other Tanaids, at least in the female sex, by the rudimentary condition of the
metasome. In both sexes, moreover the structure of the chelipeds and uropoda
may serve for recognizing the species.

Occurrence, — I have met with this form occasionally together with other
Tanaids in several places, both on the south and west coasts of Norway, as far
north as Kvalo, in depths ranging from 50 to 150 fathoms.

Gen. PseUdOtanalS, G. O. Sars, 1880,

Generic Characters. — Body short and stout, not very different in the 2 sexes,
with the cephalosome more or less contracted in front, and having no distinct
ocular lobes. The 3 anterior segments of mesosome much shorter than the 2
succeeding ones. Metasome not broader than the mesosome, and composed of 6
well-defined segments. Eyes imperfectly developed, or altogether wanting. Superior
antennae of same structure in the 2 sexes, very narrow, 3-articulate ; inferior an-
tennae almost of same size as the superior. Mandibles comparatively small, cut-
ting part in the right mandible simple, minutely serrulate, in the left one
provided with a rather large secondary lamella, molar expansion in both mandi-
bles very narrow, styliform. Maxillipeds w4th the masticatory lobes coalesced.
Chelipeds large, of a similar structure in the 2 sexes, hand very much elongated,
fingers narrow and acuminate. Pereiopoda slender and elongated ; 1 st pair somewhat
differing from the others, which are subsimilar in structure, each having a remark-
ably strong, cultriform spine at the end of the carpal joint inside. Pleopoda
sometimes wanting in female. Uropoda biramose, both rami well-defined and bi-
articulate. Incubatory pouch formed by only 2 lamellae, issuing from the bases
of the 4th pair of pereiopoda.

EemarJcs, — This genus agrees with the genus Tanais in the less conspicu-
ous sexual difference, and in the structure of the incubatory pouch, but otherwise
differs very materially, both as to its outward appearance, and to the structure
of the several appendages. It comprises as yet 7 species, 3 of which belong to
the Norwegian fauna, and will be described below. Of the other 4, the one,
jP. Willemoesi (Studer), has been taken off the Kerguelen Islands, the second, P.
mediierramea G. 0. Sars, at Spezia, and the other 2, P. affi/nis and P. 'Crassi-
cornis Hansen, in the Kara Sea.

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1. Pseudotanais foreipatus CLSliebt^).

fPL XVIL ^. I.)
Tamtat fK^rcioaha, Li.:jeb.>r;p. L c p. 16.

Sff<:nfit Charaeieri^, — R^ily of female >carcelj more than 4 times as long
as it is \myCiA, in male still shorter an*l stouter. CVphalo-^^me greatlv narrowed
anteriorij. with the front tran^verselv truncated. The first 3 segments of meso-
some oomlnned not exoee^ling the length of the 4th segment, which about eqoals
in size the 5tlu both being quadrangular in shape; la^ segment much shorter.
Metasome in female abrmt the length of the la->t 2 segments of mesosome com-
bined. and slightlj narrowed distallj. terminal segment obtusely rounded at the
tip; that in male much more fully developer], equalling about ' 3 of the length of
the body. Eyes in both sexes whoUy wanting. Superior antennae about the length
of the cephalosome, basal joint not quite attaining the length of the other 2 com-
bined, lasi joint longer than the middle one. Chelipeds very large, attaining al-
most half the length of the body, hand twice as long as the carpus, fingers very
narrow, equalling the palm in length, and nearly straight, but distinctly fordpate,
the thumb being deeply sinuated at the base inside. First pair of pereiopoda with
the propod^ joint conically tapered, dactylus very slender, setiform; carpal spine
of the succeeding pairs not very large. Pleopo<la in female wholly wanting.
Uropoda but little longer than the terminal segment of the metasome, outer ramus
nmdi shorter and narrower than the inner. Length of female 1.40 mm., of nude
1.00 mni«

Itemarks. — This is the first recorded species> and may therefore be re-
garded as the type of the genus. It is easily recognized by the forcipate cha-
racter of the chelipeds, not found in any of the other species, and equally dis-
tinct in both sexes.

Occurrence. — The species occurs along the whole Norwegian coast, as far
north as Kvalo, but nowhere in any abundance.

Diytrif/ution. — Bohuslan (Lilljeborg), Oresund (Meinert)

2. Pseudotanals lilUeborgi, G. 0. Sars.

(PI. XVU, fig. 2.)
Fiseudotanais lAUjdxyrgif G. O. Bars, 1. c. p. 48.

Specific Characters, — 9- Body somewhat more robust than in the prece-
dhig species, being scarcely 4 times as long as it is broad, and conspicuously de-
pressed. Cephalosome rather large, and less abruptly narrowed anteriorly, front

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^UN 2 1897


obtusely rounded. The first 3 segments of mesosome combined somewhat exceed-
ing in length the 4th segment, which is about the same size as the 5th, both being
almost twice as broad as they are long; last segment, as usual, considerably
smaller. Metasome about the length of the last 2 segments of the mesosome
combined, and distinctly narrowed distally. Eyes present, but very small, puncti-
form, occurring on the sides of the cephalosome, at some distance from the frontal
margin. Superior antennae with the last 2 joints of about equal length, and
combined, not quite attaining the length of the basal one. Chelipeds very strong,
hand oblong oval, not attaining twice the length of the carpus, fingers shorter
than the palm, and not forcipate. Pereiopoda resembling in structure those in
the preceding species, though perhaps somewhat less slender; carpal spine of the
5 posterior pairs comparatively larger, and more conspicaously cultriform. Pleo-
poda (in female) wholly wanting. Uropoda of about same appearance as in
P. foreipatus. Length of female 1.55 mm.

EemarJcs. — Though rather nearly allied to the preceding species, the
present form may be easily distinguished by the somewhat different form of the
cephalosome, the presence of distinct, though very small eyes, and by the cheli-
peds not being forcipate.

Occurrence. — The only place where I have observed this form, is in the
Varanger Fjord at Vadso. It occurred here rather sparingly in a depth of 100 —
120 fathoms. Out of Norway, it has not yet been recorded.

3. Pseudotanais maeroeheles, G. 0. Sars.

Fsendotanais macrocheleSt G. O. Sars, 1. c. p. 47.

Specific Characters, — 9- Body very short and compact, scarcely more
than 3 times as long as it is broad. Cephalosome scarcely exceeding in length
the 3 anterior segments of mesosome combined, and strongly contracted in front,
tip narrowly truncated. Free segments of mesosome about as in the 2 preceding
species. Metasome gradually narrowed distally, with the terminal segment evenly
rounded at the tip. Eyes wholly absent. Superior antennae very slender, consider-
ably exceeding the cephalosome in length, last joint longer than the 2nd, and
both combined, about the length of the basal one. Chelipeds exceedingly large,
> attaining nearly half the length of the body, hand very much elongated, with the
fingers slender and narrow, considerably exceeding the palm in length, but not
forcipate. Pereiopoda rather slender, 1st pair with the propodal joint longer than
the 2 preceding joints combined, and conically tapered, dactylus long and seti-

6 — Crustacea.

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form; carpal spine of the suooeedhig pairs very large and oonspicnonsly cnltriform.
Pleopoda well developed, both rami tipped by long natatory setae. Uropoda of
a similar structure to that in the 2 preceding species, though somewhat longer.
Length of female 1.45 mm.

Bemarh!, — As to its general outward appearance, this species resembles,
on the whole, the 2 preceding ones, though the body is of a still shorter and
stouter form. It is, moreover, easily distinguished by the long and slender an-
tennse, the structure of the chelipeds, and the presence of well-developed pleopoda,
wholly wanting in the female of the other known species. The cai*pal spine of
the 5 posterior pairs of pereiopoda is also considerably larger than in the other
2 Norwegian species.

Occurrence. — I have met with this form occasionally in 3 widely-distant
places on the Norwegian coast, viz., in the Ohristiania Fjord, at Bekkervig, south
of Bergen, and in the Varanger Fjord at Vadso. Out of Norway, it has not yet
been recorded.

Digitized by VjOOQIC

Tribe 2.


Eemarks. — It is not easy to give any exhaustive diagnosis of this tribe,
as it comprises Isopods of extremely dififerent structure. The only essential cha-
racter common to all the forms, is the relation of the uropoda, which are not, as
in the preceding tribe, terminal, but lateral, and arranged in such a manner as
to form, with the last segment of the metasome, a caudal fan, similar to that
found in some of the higher Crustacea, the shrimps and lobsters. As to the
pleopoda, they exhibit more generally the character of true swimming organs,
though at the same time they may also serve for respiration, and it is only in ex-
ceptional instances that the latter function is exclusively devoted to them. By far the
greater number of the forms seem to lead a parasitic, or at least semi-parasitic exi-
stence, and for this reason, the oral parts are often found to be peculiarly modified,
and, moreover, a number of the legs, in some cases all of them, to assume a more or
less pronouncedly prehensile character. The tribe includes 6 very distinct families,
viz., AnthuridcBj Onathiidce, Cymothoidce, SerolidaSj Sphcpromidce and Limnoriidce;
but of these, the 3rd has generally been again subdivided into 6 families, viz.,
uEgidce, Cirolanidcej Corallanidce, AlcironidcSj Barybrotidce and Cymothoidce, thereby
increasing the number of families to no less than 1 1 in all. Five of these families
are represented in the fauna of Norway, and will be here treated of.

Fam. 1. Anthuridae.

Characters, — Body long and slender, subcylindric in form, and rather flex-
ible. Head comparatively small. Segments of mesosome all well defined, and

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without distinct coxal plates. Metasome comparatively short, with the anterior
segments sometimes coalesced, telson generally well defined, linguiform. Both
pairs of antennae, at least in female, short and subequal in length, originating
close together, the one pair beneath the other. Oral parts modified for perfora-
tion and suction. Legs composed of the normal number of joints, the basal and
ischial ones being rather slender, and forming together a genicular bend ; 1st pair,
as a rule, much stronger than the others and subcheliform ; the 2 succeeding pairs
likewise subcheliform, but much feebler; the 4 posterior pairs ambulatory. Pleopoda
chiefly branchial in character, 1st pair large, more or less covering the others.
Uropoda with the outer ramus extending upwards, so as generally to arch over
the base of the telson. Incubatory pouch apparently not formed by distinctly de-
fined lamellae.

Remarks. — In their general outward appearance, the forms belonging
to this family somewhat recall the Tanaidw, having a similar long and nar-
row body, and in some cases, there is even to be found a slight attempt at a
cheliform structure of the 1st pair of legs. But otherwise, the two families are
widely dififerent. The structure of the oral parts would seem to point to a para-
sitic habit, but in none of the forms has the mode of parasitism as yet been
stated. The manner in which the metasome terminates is very peculiar, and un-
like that found in other Isopoda; for the telson is well defined from the last
segment, and more or less strongly deflexed, whereas the outer ramus of the uro-
poda extends upwards so as to arch over the base of the telson, thereby giving
the caudal fan a somewhat cup-shaped appearance. It is indeed from this
character that the name Anthura, given to the typical genus, has been derived.
In some of the exotic forms, however, this peculiar formation would appear to
be less pronounced than in the northern forms. Several genera have been esta-
blished in recent times, amounting to about 10 in all. Of these, only 2 are repre-
sented in the fauna of Norway.

Gen. 1. Calathura, Norm. & Stebb., 1886.

Generic Characters, — Body moderately slender, with the 2nd segment of
mesosome very movably connected, both with the preceding and succeeding segments,
dorso-lateral carinse in all the segments well marked. Metasome comparatively
short, with the segments not very distinctly defined, though apparently present
in the normal number. Eyes imperfectly developed, or quite wanting. Antennae
subequal in length, both pairs having the flagella multi-articulate; the superior

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ones scarcely diflferent in the two sexes. Buccal mass projecting in front as a
sharply-pointed cone. Mandibles terminating in a lancet-like point, and having
inside, a flexuous lamella, by which a channel-like groove is formed, leading from
the tip to the base of the mandible, palp well developed, 3-articulate. Anterior
lip narrow, terminating in an obtusely conical point; posterior lip tapering dis-
tally, and slightly bifid at the tip. Anterior maxillae simple, spear-like, terminal
part armed with recurved teeth. Posterior maxillae wanting. Maxilliped^ with
the basal part narrow oblong, projecting at the end, inside, to a triangular, poinded
masticatory lobe, palp distinctly 3-articulate, with the terminal joint rather large^
lamelliform, epignath very small, rounded. 1st pair of legs powerfully developed,
meral joint transversely expanded, propodos large and tumefied, with the palmar

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Online LibraryGeorg Ossian SarsAn account of the Crustacea of Norway: with short descriptions and ..., Volume 2 → online text (page 5 of 9)