A new species of Caprellinoides (Crustacea: Amphipoda: Phtisicidae) from the Antarctic
Helgol Mar Res
A new species of Caprellinoides (Crustacea: Amphipoda: Phtisicidae) from the Antarctic
José Manuel Guerra-García 0
0 J.M. Guerra-García (
A new caprellid species, Caprellinoides singularis, is described and illustrated based on the material collected on the Polarstern Cruise ANT XVII/3 from the Branfield Strait. The most striking characteristic of this species is the presence of bilobed gills on pereonites 3 and 4. The genus Caprellinoides is revised. Caprellinoides antarctica Schellengerg, 1926 and Caprellinoides spinosus Barnard, 1930 are considered junior synonyms of Caprellinoides tristanensis Stebbing, 1888 and Caprellinoides mayeri (Pfeffer, 1888), respectively. The new species, C. singularis, is compared with the remaining species in the genus Caprellinoides: C. tristanensis and C. mayeri, which are illustrated in detail.
Caprellidean amphipods; Caprellinoides singularis; Caprellinoides tristanensis; Caprellinoides mayeri; Antarctic
The Antarctic areas have traditionally been too
inaccessible to permit the development of large marine research
programmes. Nevertheless, the Antarctic fauna is of great
interest due, in part, to the high level of endemism
observed in certain groups. This appears to be attributable to
a process of speciation as a consequence of the protracted
period of isolation of the fauna inhabiting the oceanic
environment around Antarctica
(Clarke and Crame 1992)
The recent Polarstern surveys, carried out within the
framework of the international EASIZ (Ecology of the
Antarctic Shelf Ice Zone) Programme, represent a
significant effort to improve our understanding of certain, as yet
poorly known, groups in the Southern Ocean.
The caprellids, although very important as secondary
and tertiary producers in ecosystems, have not been
sufficiently studied. As
Takeuchi and Takeda (1992)
pointed out, the caprellidean amphipods of the Antarctic and
Subantarctic Seas were first studied by
and also by
, 1888) in his general reports
on the 'Challenger' Expeditions.
the Caprellidea collected from the Siboga Expedition.
Additional work on Antarctic caprellids was carried out
redescribed Protellopsis kergueleni Stebbing 1888 and
, based on the material
collected by the T/S Umitaka-Maru in the Antarctic Sea.
McCain and Gray (1971)
reviewed the taxonomy of the
Antarctic and Subantarctic Caprellidea and listed 21
valid species of 11 genera including six new species.
studied the Caprellidea collected by the
12th and 15th French Antarctic Expeditions.
resurrected two species of the genus
Caprellinoides (i.e. Caprellinoides antarctica
and Caprellinoides spinosus
, which had
been considered junior synonyms of C. mayeri
McCain and Gray (1971)
. Since the works of
, 1974) no additional information on the
Antarctic caprellids was published until
who studied the collection of caprellids from the French
expeditions to Adélie Land (Antarctica) and islands of
the Southern Indian Ocean, and from the Chilean
expeditions to the South Shetlands islands. All the identified
taxa (seven species in six genera) were previously
recorded from these waters but new localities were given
and some of the taxa were reillustrated in detail.
Takeuchi and Takeda (1992)
redescribed two species of the
Antarctic Caprellidea, Aeginoides gaussi
and Dodecasella elegans
and Lützow-Holm Bays, Antarctica, collected during the
Japanese Antarctic Research Expedition (JARE-26
A striking specimen of an undescribed caprellid
species was collected on the last Polarstern cruise and is
described and illustrated in the present paper. Additional
material from Museum collections has been consulted to
clarify the genus Caprellinoides.
Materials and methods
Caprellinoides singularis sp. nov. was collected on the Polarstern
Cruise ANT XVII/3, sponsored by the Alfred Wegener Institute
für Polar- und Meeresforschung, Bremerhaven, during the austral
summer of 2000. The caprellid was fixed in 10% formalin on
board ship and preserved in 70% ethanol. The specimen was
photographed, then dissected under microscope, and illustrations were
made with the aid of a camera lucida. Permanent mounts of the
mouthparts were made in polyvinyl lactophenol. Type material
(holotype) has been deposited at the Zoologisches Institut und
Zoologisches Museum, Hamburg, Germany (ZIZMH) with the
identification number k-39816.
The location of the additional specimens of Caprellinoides
examined is indicated by the following abbreviations:
BMNH, British Museum of Natural History, London
CMNC, Canadian Museum of Nature
MNB, Museum für Naturkunde, Berlin
MNHN, Muséum National D'Histoire Naturelle, Paris
ZIZMH, Zoologisches Institut und Zoologisches Museum,
JMGG, Private collection of José M. Guerra-García.
The following material has been consulted:
one male, two females, two juveniles, MNB 20419
(type material): two males,
five females, ZIZMH 21899
Fig. 1a, b Caprellinoides
singularis sp. nov. Holotype:
a lateral view; b pereonites 3
and 4 showing the bilobed gills
(arrows). Scale bars: 2 mm (a),
1 mm (b)
(non-type material): one
male collected from Polarstern ANT XVII/3, JMGG; one male,
one female collected from Polarstern ANT XIV/2, MNB
Caprellinoides tristanensis Stebbing, 1888 (non-type material):
one male BMNH 3418; three males, one female, CMNC
2001–0003, one male MNHN Am4852.
Order Amphipoda Suborder Caprellidea Family Phtisicidae Genus Caprellinoides Stebbing, 1888
Caprellinoides singularis sp. nov.
Holotype: ZIZMH k-39816, one male specimen,
Polarstern ANT XVII/3, Stn. 56/158, Branfield Strait,
63°4.42′S 57°31.36′W, depth 94–95 m, 26 April 2000,
Holotype male (ZIZMH k-39816).
Body length: 7.9 mm.
Lateral view (Figs. 1a, 2). Head regularly convex
with a rounded projection. Eyes reduced to 6 ocelli.
Suture between head and pereonite 1 present. Pleura
widened in pereonites 3 and 4. Pereonite 5 the longest.
Pereonites 2–5 each carrying a mid-dorsal and a
posterior blunt projection. Gills bilobed, oval and subequal cle carrying an acute projection distally. Flagellum
3-ar(Fig. 1b). ticulate.
Mouthparts (Fig. 3). Upper lip symmetrically bilobed, Gnathopod 1 basis as long as ischium to carpus
comsmooth. Mandibles with palp; mandibular molar absent; bined (Fig. 4). Propodus triangular, carrying two
proxiright mandible with an incisor divided into 6 teeth and mal acute spines. Palm smooth. Dactylus not serrated,
lacinia mobilis serrated and provided with 2 teeth; left distally bifurcate, carrying 8 setae.
mandible with incisor also divided into 6 teeth but lacin- Gnathopod 2 inserted in the anterior half of pereonite
ia mobilis 4-toothed not serrated; palp 3-articulate, arti- 2 (Fig. 4). Basis a little shorter than pereonite 2. Merus
cle 2 of left mandible with 1 seta, lacking in right mandi- expanded ventrally, carpus very short. Propodus slender,
ble; setal formula 1-3-1 on apical article. Lower lip with length about twice width. A proximal projection carrying
inner lobes slightly demarcated; outer lobes with small a single grasping spine. Two more projections medially
setulae apically. Maxilla 1 outer lobe with 5 simple in the palm. Dactylus smooth.
teeth; distal article of the palp with 4 spine on apical end Pereopod 5 reduced, 12 times shorter than pereonite 5,
and a setae medially. Maxilla 2 outer and inner lobe sub- with 3 articles (Fig. 5). Proximal article and penultimate
equal, carrying on each one 3 setae distally. Maxilliped article subequal in length; distal article short, about half the
inner plate small and slender, carrying 2 setae on end; in- length of penultimate article. Proximal and penultimate
arner and outer plate almost fused; outer plate about three ticle each carrying 1 seta, distal article with 5 setae.
times larger than inner plate carrying 3 setae distally and Pereopod 6 with 6 articles (Fig. 5). Propodus with a
2 medially; article 4 of the palp serrated distally, provid- proximal projection carrying a grasping spine.
ed with a pair of distal plumose setae. Pereopod 7 larger than pereopod 6 (Fig. 5). Basis with
Antenna 1 short, about one-fifth of body length a pair of ventral acute teeth situated distally. Carpus with
(Fig. 4). Article 2 of the peduncle the longest. Flagellum a pair of ventral rounded teeth situated proximally.
Propcomposed of 8 articles. odus with a proximal projection carrying a single
Antenna 2 as long as peduncle of antenna 1 (Fig. 4). ing spine apically and several strong short spines along
Swimming setae absent. Proximal article of the pedun- the palm.
Abdomen with a pair of lobes carrying a setae and a
single dorsal lobe (Fig. 5). Penes small situated laterally.
Etymology The species name refers to the singularity of the species, which possesses bilobed gills, a unique characteristic in the Caprellidea.
Geographic and depth distribution At present, C. singularis is known only from the Branfield Strait, depth 94–95 m.
The new species, C. singularis sp. nov., is closest to C.
. The type material of C. mayeri is
illustrated here in detail for the purpose of comparison
(cf. Fig. 6 with Fig. 2, Fig. 7 with Fig. 3, Fig. 8 with
Fig. 4 and Fig. 9 with Fig. 5). After a careful
examination of the specimens of C. spinosus and after consulting
the literature and figures included in
the author can state that C. spinosus
is a junior synonym of C. mayeri.
Fig. 7 Caprellinoides mayeri
. Male: A, upper lip;
B, lower lip; C, maxilliped; D, right mandible; E, left mandible;
F, maxilla 1; G, maxilla 2. Scale bars: A–F: 0.1 mm; G: 0.05 mm
A further revision of type material and non-type
material of C. antarctica and C. tristanensis revealed that
all the specimens belonged to the same species and,
therefore, C. antarctica is really a junior synonym of C.
tristanensis, which is also illustrated in detail here (cf.
Fig. 10 with Fig. 2, Fig. 11 with Fig. 3, Fig. 12 with
Fig. 4 and Fig. 13 with Fig. 5). Consequently, we can
consider three valid species in the genus Caprellinoides:
C. mayeri, C. singularis and C. tristanensis. A
comparison of selected characteristics between the three species
is presented in Table 1.
established the genus Caprellinoides
based on C. tristanensis Stebbing, 1888, which was
collected from the ocean off Nightingale Island, Tristan da
Cunha, at 201 m depth. Three additional species have
been described: C. mayeri
primarily as Caprellina mayeri Pfeffer, 1888 from South
Georgia; C. antarctica
during the Deutsche Südpolar-Expedition, and C.
, collected from the British Antarctic
Expedition. The four species in Caprellinoides were
McCain and Gray (1971)
as C. mayeri.
resurrected C. antarctica
and C. spinosus
, using material from French expeditions
to Adélie Land (Antarctica) and islands of the Southern
Indian Ocean, and from Chilean expeditions to the South
Fig. 11 Caprellinoides
tristanensis Stebbing, 1888. Male:
A, upper lip; B, maxilla 1;
C, maxilla 2; D, maxilliped;
E, right mandible; F, left
mandible. Scale bars: 0.1 mm
(lower lip missing)
Shetlands island, figured in detail C. mayeri and C.
tristanensis. A detailed comparison between them revealed
that both species were valid, reinstating C. tristanensis
as a distinct species.
did not figure C. antarctica
and C. spinosus, she reported the presence of slight
differences in the abdomen, pereopods, male gnathopod 2
and body proportions based on previous literature,
indicating that both species were probably valid.
also reported that although C. antarctica was very
similar to C. tristanensis, minor differences in body
lateral ornamentation and proportions in the propodus of
male gnathopod 2 would make it probable that both
species were also valid. Therefore, until the present paper,
the genus Caprellinoides was composed of four species:
C. antarctica, C. mayeri, C. spinosus and C. tristanensis.
After consulting the literature and material from
different Museums, the author agrees with
that C. mayeri and C. tristanensis are valid species (see
Table 1). However, C. antarctica and C. spinosus are
considered synonyms of C. tristanensis and C. mayeri,
respectively, as no constant differences could be
established between C. antarctica and C. tristanensis on the
one hand and between C. mayeri and C. spinosus on the
Apart from the unique presence of bilobed gills, C.
singularis differs from C. mayeri and C. tristanensis
mainly by the presence of reduced ocelli, the presence of
5 teeth in the maxilla 1 outer lobe and the penes reduced
and rounded (Table 1).
Stebbing, 1888 and Caprellinoides singularis sp. nov. (comparison
is based on male specimens)
Reduced to 6 ocelli
With dorsal projections
Pereonites not elongate
2 medial projections
Reduced and rounded
The most striking characteristic in C. singularis is,
without doubt, the presence of bilobed gills. This
characteristic is unique, so far, in the Caprellidea.
reported the Pseudoprotomina–Perotripus species
group to have three pairs of gills on pereonites 2–4 (six
gills in total). Seventeen of the 23 genera included in the
family Phtisicidae possess three pairs of gills, but these
are non-bilobed. All other Caprellidea have gills that are
unilobed and simple, never bilobed as in C. singularis.
Steele and Steele (1991)
have studied the
structure and organisation of the gills in the gammaridean
Amphipoda and reported that bilobed coxal gills are found
on Gammaracanthus spp., Lysianassoidea and a few other
species. The brackish amphipod family Ansiogammaridae
has been characterised by the presence of sternal gills.
Although the arrangement of thoracic gills has been
studied intensively in decapods and has contributed
substantially to their classification, there is little detailed
information available for the other Malacostracans which
also have thoracic gills (stomatopod, syncarid,
lophogastrid, amphipod and euphasiacean orders). Although most
of the gammaridean amphipods possess only a single,
simple gill on each pereopod, the presence of bilobed
gills in Gammaracanthus and lysianassoids suggests that
this is the plesiomorphic state and that in most
amphipods the outer lobe has been lost. As
Steele and Steele
pointed out, in the uristid and lysianassid
lysianassoideans the outer lobe is confined almost
exclusively to pereopods 5 and 6, whereas in the more
primitive Eurythenes and Alicella the outer lobe is also found
on the anterior gills (pereopods 2–4). The outer lobes are
evidently being lost through regressive evolution in the
more advanced lyssianassoids.
Acknowledgements Special thanks to my colleagues P.J.
LópezGonzález and M. Conradi for placing at my disposal the striking
specimen of Caprellinoides singularis. Support for this work
was provided by the CICYT projects ANT98–1739-E and
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