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Egg cases of 21 oviparous chondrichthyan species from the south-west Atlantic Ocean are described and compared. The catshark Schroederichthys bivius has a cigar-shaped egg case with curled tendrils only at the posterior end. Egg cases of the elephant fish Callorhinchus callorynchus are spindle-shaped with anterior and posterior tubular extensions and lateral flanges. The skate Amblyraja doellojuradoi presents medium-sized egg cases (71 mm in length) with a lateral keel extending to the first portion of the horns. The endemic skate species of the genus Atlantoraja have medium to large egg cases (69-104 mm in length) and present relatively large posterior horns. Egg cases of the genus Bathyraja have a medium size, 75-98 mm in length, and are characterized by a very similar morphology, a relatively smooth to rough surface case and posterior horns strongly curved inwards. Egg cases of the genera Dipturus and Zearaja are very large, 115-230 mm in length, and have a well-developed posterior apron. Despite the problematical identification of skates at species level, the egg capsules of the endemic genus Psammobatis are easily diagnosed; the capsules are small (25-53 mm in length), those of Psammobatis rutrum being the smallest known to date in the world. Egg cases of Rioraja agassizi have a medium size, 61-68 mm in length, relatively straight sides, a smooth surface and silky attachment fibres placed in the lateral keel next to each horn. Those of the genus Sympterygia are small to medium sized, 51-86 mm in length, and display the thickest lateral keel and the longest posterior horns among the skates of the world. Egg cases can be a useful tool for identifying species and egg-laying areas; therefore, a provisional key for the south-west Atlantic Ocean chondrichthyan capsules is presented.
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Journal of Fish Biology (2011) 79, 12611290
doi:10.1111/j.1095-8649.2011.03111.x, available online at wileyonlinelibrary.com
Chondrichthyan egg cases from the south-west Atlantic
Ocean
E. Mabraga ˜
na*†‡, D. E. Figueroa*, L. B. Scenna*,J.M.Díazde
Astarloa*, J. H. Colonello§and G. Delpiani*
*Departamento de Ciencias Marinas, Facultad de Ciencias Exactas y Naturales, Universidad
Nacional de Mar del Plata, Funes 3350, B7602AYL Mar del Plata, Rep´ublica Argentina,
Consejo Nacional de Investigaciones Científica y T´ecnicas (CONICET), Buenos Aires,
Rep´ublica Argentina and §Pesquerías de Condrictios, Instituto Nacional de Investigaci´on y
Desarrollo Pesquero (INIDEP), Paseo Victoria Ocampo N1, Escollera Norte, B7602HSA
Mar del Plata, Rep´ublica Argentina
(Received 5 February 2010, Accepted 25 August 2011)
Egg cases of 21 oviparous chondrichthyan species from the south-west Atlantic Ocean are described
and compared. The catshark Schroederichthys bivius has a cigar-shaped egg case with curled tendrils
only at the posterior end. Egg cases of the elephant fish Callorhinchus callorynchus are spindle-
shaped with anterior and posterior tubular extensions and lateral flanges. The skate Amblyraja
doellojuradoi presents medium-sized egg cases (71 mm in length) with a lateral keel extend-
ing to the first portion of the horns. The endemic skate species of the genus Atlantoraja have
medium to large egg cases (69– 104 mm in length) and present relatively large posterior horns.
Egg cases of the genus Bathyraja have a medium size, 75–98 mm in length, and are charac-
terized by a very similar morphology, a relatively smooth to rough surface case and posterior
horns strongly curved inwards. Egg cases of the genera Dipturus and Zearaja are very large,
115– 230 mm in length, and have a well-developed posterior apron. Despite the problematical
identification of skates at species level, the egg capsules of the endemic genus Psammobatis are
easily diagnosed; the capsules are small (25– 53 mm in length), those of Psammobatis rutrum being
the smallest known to date in the world. Egg cases of Rioraja agassizi have a medium size,
61– 68 mm in length, relatively straight sides, a smooth surface and silky attachment fibres placed
in the lateral keel next to each horn. Those of the genus Sympterygia are small to medium sized,
51– 86 mm in length, and display the thickest lateral keel and the longest posterior horns among
the skates of the world. Egg cases can be a useful tool for identifying species and egg-laying
areas; therefore, a provisional key for the south-west Atlantic Ocean chondrichthyan capsules is
presented. ©2011 The Authors
Journal of Fish Biology ©2011 The Fisheries Society of the British Isles
Key words: Argentina; capsules; identification key; skates; sharks.
INTRODUCTION
Chondrichthyans display a great variety of reproductive modes, from oviparity to
different kinds of viviparism (from yolk-sac viviparity, the dominant mode of repro-
duction in Chondrichthyes, to placental viviparity in some sharks) (Hamlett, 2005).
‡Author to whom correspondence should be addressed. Tel.: +54 223 4751107; email: emabraga@
mdp.edu.ar
1261
©2011 The Authors
Journal of Fish Biology ©2011 The Fisheries Society of the British Isles
1262 E. MABRAGA ˜
NA ET AL.
Oviparity is characterized by the production of fertilized eggs, encapsulated in a
structurally complex capsule, that develop and hatch externally. Oviparity is found
in all skate and holocephalan species, and in some sharks (Hamlett, 2005).
Oviparous chondrichthyans in the Argentine continental shelf are represented by 24
species of skates, the elephant fish Callorhinchus callorynchus (L. 1758) and the nar-
rowmouthed catshark Schroederichthys bivius (M¨
uller & Henle 1838) (Menni et al.,
1984; Cousseau et al., 2007; Diaz de Astarloa et al., 2008). Two other oviparous
sharks, the polkadot catshark Scyliorhinus besnardi (Springer & Sadowsky 1970)
and the freckled catshark Scyliorhinus haeckeli (Miranda Ribeiro 1907) occasionally
occur in the area (Menni & Lucifora, 2007).
In spite of the fact that chondrichthyan catches in the south-west Atlantic Ocean
have considerably increased in recent years (Massa et al., 2004; Cousseau et al.,
2007), several aspects of their reproductive biology are yet unknown. Egg cases
have been described for some skates in the south-western Atlantic Ocean (Braccini
& Chiaramonte, 2002; Mabraga˜
na et al., 2002; Oddone & Vooren, 2002, 2005, 2008;
Mabraga˜
na & Cousseau, 2004; Oddone et al., 2004, 2006; Oddone, 2005; San Martín
et al., 2005; Ruocco et al., 2006; Mabraga˜
na, 2007; Concha et al., 2009). Two of
these works include an identification key based on egg-case morphology of species
of Psammobatis G¨
unther 1870 (Mabraga˜
na, 2007), and of species of Atlantoraja
Menni 1872, Sympterygia M¨
uller & Henle 1837 and Rioraja Whitley 1939 (Oddone
& Vooren, 2008); however, a comparative study including capsules morphology and
morphometry of all chondricthyan genera occurring in the area is lacking.
Egg case morphology is species specific (Ishiyama, 1958; Ebert, 2005; Ebert &
Davis, 2007) and is used as a taxonomic and ecological tool. Variations in egg case
morphology between species may also indicate differences in the habitat of where
they are deposited (Ebert et al., 2006). The identification of demersal egg cases
furnish valuable information concerning the distribution and reproductive biology
of species (e.g. breeding season, fecundity and fertility, incubation period and egg
laying and nursery areas). This information is crucial for the conservation of these
species. Given the importance of egg case identification, the aim of this study was to
provide the description and diagnostic characteristics of specific egg cases occurring
in the Argentine continental shelf.
MATERIALS AND METHODS
Oviparous species were collected from bottom-trawl surveys carried out by the Instituto
Nacional de Investigaci´
on y Desarrollo Pesquero, (INIDEP; National Institute of Fishery
Research and Development, Argentina). The survey area included the south-west Atlantic
Ocean between 34and 55S, from the coastline to 200 m depth (Fig. 1). For egg case
identification associated with the correct species, capsules were removed from females in the
uterus, except those of C. callorynchus, which were obtained from the sea bed. Addition-
ally, egg cases were taken with a dredge close to banks of Patagonian scallop Zygochlamys
patagonica. Egg cases were also collected, after deposition, from specimens in captivity in
the Museo del Mar aquariums. Egg cases were fixed and preserved in 10% formalin, and
deposited in the collection at Laboratorio de Ictiología de la Universidad Nacional de Mar
del Plata, Mar del Plata, Argentina.
Eight morphometric characteristics were recorded following standard methods (Hubbs &
Ishiyama, 1968; Ishiyama & Ishihara, 1977; Ebert & Davis, 2007). In addition, keel thickness
and straight distance from the anterior apron margin to the curvature of the anterior horn
©2011 The Authors
Journal of Fish Biology ©2011 The Fisheries Society of the British Isles, Journal of Fish Biology 2011, 79, 1261 1290
CHONDRICHTHYAN EGG CASES 1263
70° 68° 66° 64° 62° 60° 58° 56° 54° 52° 50°
54°
52°
50°
48°
46°
44°
42°
40°
38°
36°
34°
Uruguay
Argentina
100 m
50 m
200 m
Fig. 1. Study area showing the sites where females bearing egg cases were found: ,Amblyraja doellojuradoi ;
,Atlantoraja castelnaui ; , Atlantoraja cyclophora; , Atlantoraja platana ; , Bathyraja albomacu-
lata;,Bathyraja brachyurops ; , Bathyraja macloviana; , Bathyraja magellanica ; , Callorhinchus
callorhynchus;,Zearaja chilensis ; , Dipturus trachyderma; , Psammobatis bergi ; , Psammobatis
rutrum;,Psammobatis extenta ; , Psammobatis normani ; , Psammobatis rudis ; , Psammobatis
lentiginosa;,Rioraja agassizi ; , Schroederichthys bivius; , Sympterygia bonapartii.
(aHL2) were recorded (Fig. 2). All measurements were taken with vernier calipers at 0·1mm
precision.
STUDY AREA
The Argentine continental shelf comprises a part of the south-west Atlantic Ocean between
34and 55S. Water masses in this region consist of several water types: coastal, sub-
Antarctic, subtropical and mixed waters (Bisbal, 1995). In the north, the circulation is influ-
enced by the warm, more saline, south-flowing Brazil Current, which runs along the conti-
nental margin of South America and moves offshore at c. 36–38S (Olson et al., 1988). In
the south, a low salinity current of sub-Antarctic origin flows north along the coast, from the
Strait of Magellan (5230S) to 40–42S, where it veers offshore and flows northwards
over the outer shelf and slope. These water masses are modified substantially by inflow of
©2011 The Authors
Journal of Fish Biology ©2011 The Fisheries Society of the British Isles, Journal of Fish Biology 2011, 79, 1261 1290
1264 E. MABRAGA ˜
NA ET AL.
pA
aA
aHL aHL2
ECL
Fl
WLK
TLK
pHL
MAW
MIW
Fig. 2. Generalized egg case showing the morphometric characters utilized in the study: ECL, egg case length
(without horns); MAW, egg case width (maximum); MIW, egg case width (minimum); LaH, unfurled
anterior horn length; pHL, posterior horn length; LKW, lateral keel width; LKT, lateral keel thickness;
aA, anterior apron; pA, posterior apron; aHL2, straight distance from anterior apron to apex of anterior
horn; Fl, flange.
glacial waters from the Magellan Strait at 5230S and freshwater inputs from the Negro and
La Plata Rivers (Guerrero & Piola, 1997). These systems correspond to two biogeographic
provinces: the Argentine Province in the north, extending north to Rio de Janeiro, Brazil,
and the Magellanic Province in the south, which also includes southern Chile (Menni &
L´
opez, 1984).
RESULTS
One hundred and forty-six egg cases of 21 species of Chondrichthyes belonging
to nine genera were examined.
SUBCLASS HOLOCEPHALII, ORDER CHIMAERIFORMES
There is only one species in the south-west Atlantic Ocean, C. callorynchus,
endemic to South America.
©2011 The Authors
Journal of Fish Biology ©2011 The Fisheries Society of the British Isles, Journal of Fish Biology 2011, 79, 1261 1290
CHONDRICHTHYAN EGG CASES 1265
Fl
(a) (b)
Fig. 3. (a) Dorsal view of the egg case of Callorhinchus callorynchus (Fl, flange). Scale bar =1 cm per unit.
(b) Surface of case (×40).
Callorhinchus callorynchus has relatively large and spindle-shaped egg cases
[Fig. 3(a)], with anterior and posterior tubular extensions and lateral flanges. The
dorsal surface of the case is relatively rough to touch due to the presence of undu-
late longitudinal striations in a zig-zag pattern [Fig. 3(b)]. The ventral surface is
smooth. The lateral flanges show transversal grooves oriented anteriorly on the ante-
rior tubular zone, straight or transversal in the section that houses the egg and in the
posterior two thirds part of case the flanges have two strong grooves oriented pos-
teriorly and followed by less pronounced grooves. The posterior tubular extension
has a mid keel and two lateral keels, whereas the anterior tubular extension only
possesses two pilous lateral keels. The dorsal case surface presents fibrous sheets of
byssus-like material, especially on lateral flanges.
Egg case measurements (n=3): length: 240248 mm; maximum width: 75–
92 mm; case width without flange: 3642 mm.
Callorhinchus callorynchus is widely distributed in the south-west Atlantic Ocean
from 23to 55S(L
´
opez et al., 2000), and in the south-eastern Pacific Ocean to
15S, from the coast to 200 m depth (Chirichigno, 1998). Egg cases were collected
from benthic samples at 4055S at 135 m depth (Fig. 1).
©2011 The Authors
Journal of Fish Biology ©2011 The Fisheries Society of the British Isles, Journal of Fish Biology 2011, 79, 1261 1290
1266 E. MABRAGA ˜
NA ET AL.
(a) (b)
Fig. 4. (a) Dorsal view of the egg case of Schroederichthys bivius. Scale bar =1 cm per unit. (b) Surface of
case (×40).
SUBCLASS ELASMOBRANCHII, ORDER
CARCHARINIFORMES, FAMILY SCYLHIORHINIDAE
This family in the south-west Atlantic Ocean comprises four species; three of them
have been recorded in the Argentine Continental Shelf (Menni & Lucifora, 2007;
Eschmeyer & Fricke, 2011): S. bivius,S. besnardi and S. haeckeli ; but only the first
is commonly found in Argentine waters and their capsules are described here. The
other two species have been reported from Uruguayan waters and their egg cases
were described from Brazil waters (Gomes & de Carvalho, 1995).
Schroederichthys bivius has a cigar-shaped egg case [Fig 4(a)], with fine and
straight longitudinal striations on the dorsal and ventral surfaces [Fig. 4(b)]. The
lateral flanges are narrow and posses fine transversal striae. The anterior border is
convex and tendrils are absent. The posterior border of the case has curled, filamen-
tous tendrils, longer than the egg case length [Fig. 4(a)].
Egg case measurements (n=13): length: 5868 mm; width: 2227 mm; lateral
keel width: 1·7–2·5 mm; keel thickness: 1·5–4 mm.
Schroederichthys bivius occurs in the south-west Atlantic Ocean from southern
Brazil (33S) south to the Beagle Channel (55S) (Soto, 2001), and in the south-
east Pacific Ocean to Valparaiso (33S), from 80 to 200 m depth. Females bearing
egg cases were found in northern Patagonian waters (Fig. 1).
ORDER RAJIFORMES, FAMILY RAJIDAE
Egg cases of skates are generally rectangular in shape with a horny process in
each corner. Measurements are presented in Table I. Diagnostic characteristics for
each genus and species are given below.
©2011 The Authors
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CHONDRICHTHYAN EGG CASES 1267
Table I. Measurements (range and mean ±s.d.; mm) of the egg cases of 19 species of skates from Argentinian waters (Fig. 1)
Species nECL MAW MIW aHL pHL LKW LKT aA pA aHL2
Atlantoraja
cyclophora
3 Range 69·0–75·037·5–44·633·7–39·652·0–54·098·0– 103·02·4–2·51·1–2·05·0–5·611·0–12·023·0–27·0
Mean ±s.d.51·7±3·238·1±3·834·4±3·338·0±1·073·5±2·54·0±0·11·5±0·54·7±0·39·9±0·630
·1±2·0
Atlantoraja
castelnaui
5 Range 96·7 103·8 68–78·263·6–70·367·0–77·0 118·0 155·05·0–8·01·9–3·46·2–10·512·1–22·350·0–61·0
Mean ±s.d.99·8±3·772·4±3·866·3±2·571·0±5·0 133·6±13·46·9±1·12·4±0·67·6±1·815·9±3·855·7±4·5
Atlantoraja
platana
3 Range 71·0–72·044·8–47·2 39–40·243·6–56·3 110 128 2·3–2·61·6–2·04·8–6·710·8–13·624·7–25·0
Mean ±s.d.71·6±0·546·1±1·239·7±0·650·6±6·5 121·7±10·12·5±0·21·8±0·25·5±1·112·1±1·424·8±0·2
Amblyraja
doellojuradoi
5 Range 67·0–73·047·3–54·238·0–48·043·0–50·050·0–68·04·3–6·00·3–0·66·0–8·312·5–16·021·0–26·0
Mean ±s.d.70·0±2·550·7±3·043·6±3·945·3±3·060·8±8·55·5±0·80·5±0·17·5±0·914·5±1·724·4±2·0
Bathyraja
albomaculata
8 Range 89·7–98·052·5–68·449·0–53·061·0–75·060·0–88·03·9–6·22·3–2·85·8–8·015·0–26·028·7–45·0
Mean ±s.d.95·9±3·660·0±4·951·2±1·570·0±5·070·0±8·65·1±1·02·6±0·27·0±0·820·8±3·733·8±5·5
Bathyraja
brachyurops
11 Range 82·0–93·053·0–65·442·0–58·060·0– 103·070·0 117·03·2–6·00·5–1·63·4–9·0 11–19·631·0–39·0
Mean ±s.d.89·0±3·557·5±4·048·0±4·984·6±13·687·7±15·44·7±0·90·9±0·36·0±1·715·7±2·335·0±2·5
Bathyraja
macloviana
8 Range 75·0–84·943·5–48·537·8–42·044·0–60·047·0–63·02·5–4·02·5–3·05·0–12·012·4–17·021·5–29·0
Mean ±s.d.80·6±4·045·7±1·940·3±1·350·4±5·754·4±6·03·2±0·52·8±0·27·8±2·414·6±1·525·9±2·8
Bathyraja
magellanica
5 Range 79·8–88·055·5–60·042·4–45·340·0–59·085·0– 150·07·0–8·70·5–1·06·0–9·013·5–17·528·0–30·3
Mean ±s.d.83·6±4·057·6±2·243·9±1·048·0±7·3 119·8±32·17·4±0·70·7±0·37·0±1·215·5±2·029·6±0·9
Zearaja
chilensis
14 Range 115·0 158·058·7–70·852·7–67 53·0–73·063·0– 117·03·9–7·90·9–2·57·0–18·033·0–54·021·0–36·0
Mean ±s.d. 131·5±14·465·7±4·259·4±5·162
·2±6·189·6±16·65·0±1·21·7±0·512·4±3·441·4±5·727·6±4·3
Dipturus
trachyderma
2 Range 222·0 230·0 163– 154·0 100·0 107·078·0–88·074·0–78·043·0–33·00·5–1·065·0–70·056·0–65·015·0
Mean ±s.d·226·0±5·7 158·5±6·4 103·5±4·983·0±7·176·0±2·838·0±7·10·8±0·467·5±3·560·5±6·415·0
Psammobatis
bergi
10 Range 39·6–43·5 34–35·431·9–33·928·0–40·051·0–67·01·9–2·90·5–1·31·78–2·54·1–9·019·0–23·8
Mean ±s.d.41·9±1·434·7±0·432·8±0·635·4±1·05 56·8±2·82·3±0·10·8±0·32·1±0·16·1±1·221·0±1·8
©2011 The Authors
Journal of Fish Biology ©2011 The Fisheries Society of the British Isles, Journal of Fish Biology 2011, 79, 1261 1290
1268 E. MABRAGA ˜
NA ET AL.
Table I. Continued
Species nECL MAW MIW aHL pHL LKW LKT aA pA aHL2
Psammobatis
extenta
10 Range 25·5–30·917·9–20 14·9–16·617·0–26·027·0–45·01·0–1·30·5–0·91·0–1·93·0–6·011·0–15·0
Mean ±s.d.28·7±2·119·1±0·615·7±0·621·7±2·933·6±4·91·1±0·10·7±0·21·5±0·34·6±1·013·2±1·4
Psammobatis rutrum 1 Value 26·719·616·316·037·01·40·61·72·613·0
Psammobatis
normani
18 Range 41·0–52·028·8–36 25·0–32·525·0–63·055·0–76·02·2–3 0·4–0·8 2–3·84·52–8 21·4–29
Mean ±s.d.45·7±3·531·5±2·327·8±2·245·4±8·663·8±5·82·5±0·20·6±0·12·6±0·56·2±1·024·7±2·5
Psammobatis
rudis
6 Range 45·6–53·526·1–36·923·0–32·824·0–36·050·0–74·02·3–3·70·6–0·62·4–3·6 5–6·611·5–24
Mean ±s.d.49·8±3·232·9±4·829·5±4·428·7±5·063·8±10·83·0±0·60
·6±0·03·0±0·55·8±0·617·6±4·4
Psammobatis
lentiginosa
6 Range 34·6–40·6 24–27·719·2–24·518·0–25·035·0–48·01·8–2·00·6–1·0 2–3·85·6–7·711·0–15·6
Mean ±s.d.37·9±2·525·5±1·721·3±2·520·0±3·239·3±5·21·9±0·10·8±0·22·9±0·76·9±0·713·9±1·9
Rioraja
agassizi
5 Range 61·0–68·037·5–40·535·5–37·047·0–56·062·0–79·02·3–3·00·9–1·74·0–8·09·2–10·532·0–38·2
Mean ±s.d.63·8±2·639·0±1·136·1±0·552·8±4·169·6±6·92·8±0·31·3±0·45·1±1·710·0±0·534·6±2·8
Sympterygia
acuta
Range 51·2–57·532·4–36·026·4–29·0 29–39·7 180– 293 1·0–2·02·8–3·42·5–4·94·0–7·214·0–22·3
10 Mean ±s.d.54·8±2·434·4±1·527·6±0·934·9±3·0 232·1±41·91·3±0·43·1±0·23·7±0·86·1±1·018·4±3·1
Sympterygia
bonapartii
8 Range 68·3–86·541·4–52·237·0–44·840·0–58·0 117·0–158·00·5–1·95·0–6·23·7–6·26·6–12·026·0–32·0
Mean ±s.d.81·2±5·649·6±3·442·5±2·450·6±5·3 135·3±16·61·5±0·45·7±0·45·4±0·710·4±1·828·9±2·3
n, sample size; ECL, egg case length (without horns); MAW, egg case width (maximum); MIW, egg case width (minimum); aHL, anterior horn length; pHL, posterior horn length; LKW, lateral keel width; LKT,
lateral keel thickness; aA, anterior apron; pA, posterior apron; aHL2, straight distance from anterior apron to apex of anterior horn.
©2011 The Authors
Journal of Fish Biology ©2011 The Fisheries Society of the British Isles, Journal of Fish Biology 2011, 79, 1261 1290
CHONDRICHTHYAN EGG CASES 1269
Amblyraja
This genus comprises at least four species in the south-west Atlantic Ocean: the
southern thorny skate Amblyraja doellojuradoi (Pozzi 1935), the thickbody skate
Amblyraja frerichsi (Krefft 1968), the whiteleg skate Amblyraja taaf (Meisner 1987)
and the Antarctic starry skate Amblyraja georgiana (Norman 1938), but only the
first inhabits the Argentine continental shelf (Menni & Stehmann, 2000; Cousseau
et al., 2007).
The egg cases of A. doellojuradoi are medium size, 67 73 mm in length (horns
excluded), with maximum egg case width (MAW) c. 66 80% of egg case length
(ECL) and possess a remarkable lateral keel, c. 912% of MAW, extending the
length of the case, tapering off along the outer edge of the horns. The anterior horns
finish abruptly, whereas the posterior horns taper progressively [Fig. 5(a)]. The dorsal
surface of the cases, including both the lateral keels and the horns base, are covered
with fine fibroids. The dorsal and ventral surfaces of the cases are finely striated
without ridges but with fine transversal scars along the stries [Fig. 5(b)]; apparently,
no other skate egg cases have these scars. Attachment fibres are absent. The anterior
horns curl ventrally, and are flattened and hook-like towards the tips; the length of
the anterior and posterior horn is c. 6268% of ECL. The posterior apron is wider
than the anterior one. The posterior horns are flattened to a filamentous tip, relatively
short (70100% of ECL) but longer (1·1–1·6 times) than the anterior horns.
Amblyraja doellojuradoi is distributed in the south-west Atlantic Ocean between
36and 56S, and from 51 to 642 m depth; but is relatively more abundant between
36and 42S. (Menni & Stehmann, 2000; Cousseau et al., 2007). Females bearing
egg cases were found at 4059S; 5705W at 143 m depth (Fig. 1).
Atlantoraja
This genus comprises three species, the spotback skate Atlantoraja castelnaui
(Miranda Ribeiro 1907), the eyespot skate Atlantoraja cyclophora (Regan 1903)
and la Plata skate Atlantoraja platana (G¨
unther 1880), endemic to the south-west
Atlantic Ocean (Menni & Stehmann, 2000; Cousseau et al., 2007). The egg cases
(Fig. 6) are medium to large, 69– 104 mm in length (horns excluded) and present
relatively large posterior horns.
Atlantoraja castelnaui [Fig. 6(a)] has the largest case within the genus, >95 mm in
length, with MAW c. 66 81% of ECL. The base of the horns and lateral margins are
covered by adhesive fibrils. The dorsal surface of case is densely covered with woven-
like fibres [Fig. 7(a)]. Both case surfaces, except the fibrous layer, are relatively
smooth, finely striated and without ridges; these striae are irregular in size [Fig. 7(b)].
The anterior horns are slightly curved ventrally; their length is c. 6678% of ECL.
The posterior apron edge is relatively flat and wider than the anterior apron. The
lateral keel width (LKW) is narrow, c. 710% of MAW. The posterior horns are
long, c. 1·2–1·5 times ECL and c. 1·7–2·0 times the length of the anterior ones.
The aHL2 is relatively large, >50% of ECL.
Egg cases of A. cyclophora [Fig. 6(b)] are medium size (<75 mm on length),
with MAW c. 54 59% of ECL. The base of the horns, lateral margins and dorsal
face of the capsule are covered by a layer of sticky fibrils. The surface of the case is
longitudinally striated with marked ridges on the dorsal face [Fig. 7(c)]. The anterior
horns are relatively short, c. 4953% of ECL. The posterior apron edge is markedly
convex. The LKW is narrow, c. 67% of MAW. The posterior horns are long, c.
©2011 The Authors
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SC
(a)
(b)
Fig. 5. (a) Dorsal view of the egg case of Amblyraja doellojuradoi. Scale bar =1 cm per unit. (b) Surface of
case (×40). SC, scars.
1·3–1·4 times ECL, and c. 1·9 times the length of the anterior horns. The aHL2 is
relatively short, <40% of ECL.
Egg cases of A. platana [Fig. 6(c)] are medium size (<75 mm in length) with
MAW c. 63 66% of ECL. The base of the horns, lateral margins and both faces of
the capsule are covered by sticky fibrils. The case surface is longitudinally striated
with marked ridges especially on the dorsal face [Fig. 7(d)]. The posterior apron
edge is relatively flat. The LKW is narrow, c. 56% of MAW. The anterior horns
are curved inwards, their length c. 55% of ECL. The posterior horns are long (>1·5
times ECL) and c. 2·3–2·5 times the length of the anterior horns. The aHL2 is
relatively short (<40% of ECL).
Atlantoraja castelnaui and A. cyclophora are distributed in the south-west Atlantic
Ocean between Rio de Janeiro (22S) and north Patagonia (42S), from the coast
to 100130 m depth, but are more abundant in shallower waters <60 m (Menni &
Stehmann, 2000; Cousseau et al., 2007). Females bearing egg cases were found in
northern Argentina at 3860 m depth (Fig. 1). Atlantoraja platana is distributed in
the south-west Atlantic Ocean from Espirito Santo (Brazil, 20S) south to San Matías
Gulf (Argentina, 42S), from the coast to 149 m depth (Menni & Stehmann, 2000;
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CHONDRICHTHYAN EGG CASES 1271
(a) (b) (c)
Fig. 6. Dorsal view of the egg cases of (a) Atlantoraja castelnaui,(b)Atlantoraja cyclophora and
(c) Atlantoraja platana. Scale bar = 1 cm per unit.
Cousseau et al., 2007). Females bearing egg cases were found in waters adjacent to
northern Argentina and Uruguay at 120 m depth (Fig. 1).
Bathyraja
The genus comprises 11 species in the south-west Atlantic Ocean, but is rep-
resented by eight species in the Argentine continental shelf, the white-dotted skate
Bathyraja albomaculata (Norman 1937), the broadnose skate Bathyraja brachyurops
(Fowler 1910), the joined-fins skate Bathyraja cousseauae Díaz de Astarloa &
Mabraga˜
na 2004, the greytail skate Bathyraja griseocauda (Norman 1937), the Pata-
gonian skate Bathyraja macloviana (Norman 1937), the Magellan skate Bathyraja
magellanica (Philippi 1902), the multispine skate Bathyraja multispinis (Norman
1937) and the cuphead skate Bathyraja scaphiops (Norman 1937) (Menni &
Stehmann, 2000; Cousseau et al., 2007). The capsules of four of these species are
described below.
The egg cases are medium to large size, 75– 98 mm in length, and have a very
conservative morphology (Fig. 8). The posterior horns are strongly curved inwards
and the aHL2 is relatively short (<50% of case length). The surface of cases is
generally coarse, often with prickles, and rough to the touch.
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1272 E. MABRAGA ˜
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(a) (b)
(c) (d)
Fig. 7. Surface of case of Atlantoraja species showing the different patterns at magnification (×40).
(a) Atlantoraja castelnaui with woven-like fibres, (b) Atlantoraja castelnaui showing structure beneath
fibrous layer, (c) Atlantoraja cyclophora and (d) Atlantoraja platana.
Bathyraja albomaculata [Fig. 8(a)] has large egg cases (89 98 mm in length),
with MAW c. 54 75% of ECL. The case surface bears longitudinal striations with
long and thin prickles of different sizes, giving a velvety texture to the touch
[Fig. 9(a)]. Attachment fibres are absent. The LKT is relatively thick (>2 mm). The
LKW is narrow (611% of MAW). The posterior apron is wider (2·1–3·6 times)
than the anterior apron. The anterior and posterior horns are similar in length and
relatively short (<90% of ECL).
Egg cases of B. brachyurops [Fig. 8(b)] are large (82– 93 mm in length), with
MAW c. 70 81% of ECL. The egg case surface is relatively smooth, finely stri-
ated, with rasp-like denticles and without prickles [Fig. 9(b)]. Attachment fibres are
observed at the bases of the posterior horns and posterior apron. The LKT is rela-
tively thin (<2 mm). The LKW is narrow (611% of MAW). The posterior apron is
wider (1·9–4·2 times) than the anterior apron. The anterior and posterior horns are
similar in length and relatively short (<1·3 times ECL).
Bathyraja macloviana [Fig. 8(c)] has the smallest egg case within the genus
(7584 mm in length), with MAW c. 52 59% of ECL. The surface texture is coarse
and very rough to the touch due to papillose longitudinal ridges. The prickles have
different sizes and shapes [Fig. 9(c)]. Attachment fibres are absent. The LKT is rela-
tively thick (>2 mm) and the LKW is narrow (69% of MAW). The posterior apron
is wider (1·23 times) than the anterior apron. The anterior and posterior horns are
relatively short and similar in length (<75% of ECL).
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CHONDRICHTHYAN EGG CASES 1273
(a) (b)
(c) (d)
Fig. 8. Dorsal view of the egg cases of (a) Bathyraja albomaculata,(b)Bathyraja brachyurops,(c)Bathyraja
macloviana and (d) Bathyraja magellanica. Scale bar =1 cm per unit.
Egg cases of B. magellanica [Fig. 8(d)] are large (80 88 mm in length), with
MAW c. 68 70% of ECL. The capsule exhibits a wide lateral keel that is remark-
ably lighter in colour than the rest of the case. The case surface is similar to that
of B. abomaculata, but the prickles are all of uniform size [Fig. 9(d)]. Attachment
fibres are absent. The LKT is relatively thin (<2 mm). The LKW is broad (1215%
of MAW). The posterior apron is wider (1·4 3 times) than the anterior apron. The
©2011 The Authors
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1274 E. MABRAGA ˜
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(a) (b)
(c) (d)
Fig. 9. Surface of case of Bathyraja species showing the different patterns (×40). (a) Bathyraja albomaculata,
(b) Bathyraja brachyurops,(c)Bathyraja macloviana and (d) Bathyraja magellanica.
posterior horns are relatively short (c. 1·0–1·7 times ECL) but longer than the anterior
ones.
Bathyraja albomaculata occurs in the south-west Atlantic Ocean from 37to 55
S, from 70 to 815 m depth, and in the south-east Pacific Ocean to 45S (Menni &
Stehmann, 2000; Cousseau et al., 2007). Females bearing egg cases were found along
the shelf at 116154 m depth (Fig. 1). Bathyraja brachyurops is widely distributed
in the south-west Atlantic Ocean from 37to 55S, from 82 to 500 m depth, and in
the south-eastern Pacific Ocean to 45S (Menni & Stehmann, 2000; Cousseau et al.,
2007). Females bearing egg cases were found in Patagonian waters at 104137 m
depth (Fig. 1). Bathyraja macloviana is widely distributed in the south-west Atlantic
Ocean from 36to 55S, from 82 to 505 m depth, and in the south-east Pacific
Ocean to 51S (Menni & Stehmann, 2000; Cousseau et al., 2007). Females bearing
egg cases were found in Patagonian waters at 106144 m depth (Fig. 1). Bathyraja
magellanica is distributed in the south-west Atlantic Ocean from 45to 55S,
from 51 to 137 m depth, and in the south-east Pacific Ocean to 42S (Menni &
Stehmann, 2000; Cousseau et al., 2007). Females bearing egg cases were found in
southern Patagonian waters at 100113 m depth (Fig. 1).
Dipturus
In the south-west Atlantic Ocean, the genus Dipturus is represented by six species
(Díaz de Astarloa et al., 2008). Three of them inhabit the Argentine continental
©2011 The Authors
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CHONDRICHTHYAN EGG CASES 1275
(a) (b)
Fig. 10. Dorsal view of the egg cases of (a) Zearaja chilensis and (b) Dipturus trachyderma. Scale bar =1cm
per unit.
shelf: the yellownose skate Dipturus chilensis (Guichenot 1848), [Last & Gledhill
(2007) discusses the species recent transfer from Dipturus to Zearaja], the roughskin
skate Dipturus trachyderma (Krefft & Stehmann 1975) and the Argentine skate Dip-
turus argentinensis Díaz de Astarloa, Mabraga ˜
na, Hanner & Figueroa 2008. A fourth
species, the south Brazilian skate Dipturus mennii Gomes & Parag ´
o 2001, has been
recorded at the border of Brazilian and Uruguayan waters (Bernardes et al., 2005)
and could be found in Argentine waters. The capsules of only the first two species
are described here.
The egg cases (Fig. 10) are very large, 115– 230 mm in length (horns excluded),
with a well-developed posterior apron and a very short aHL2 (<40% of case length).
The dorsal and ventral surfaces of the case are covered with dense woven-like fibres.
The surface of the cases beneath the fibrous layer is relatively smooth, finely striated
and without ridges [Fig. 11]. Fibre attachments are absent.
The egg cases of yellownose skate Zearaja chilensis (Guichenot 1848). [Fig. 10(a)]
are large (115158 mm in length), with MAW c. 3960% of ECL. The LKW is
narrow (611% of MAW), the posterior apron is very broad (37– 36% of ECL)
and wider than anterior apron. The anterior horns are relatively short (3762% of
ECL), robust at the base, curving ventrally and flattened towards the tips. The poste-
rior horns are longer than the anterior horns (11·9 times), but still relatively short
(<90% of ECL), and possess a lighter flange along their inner edge.
The egg cases of D. trachyderma [Fig. 10(b)] are very large (>200 mm in length),
with MAW c. 67 73% of ECL. The LKW is very broad (21 –26% of MAW) and
©2011 The Authors
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1276 E. MABRAGA ˜
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(a)
(b)
Fig. 11. Surface of egg cases of (a) Zearaja chilensis and (b) Dipturus trachyderma showing the different
patterns (×40).
the anterior apron is also very broad (c. 30% of ECL) and wider than the posterior
apron. The anterior and posterior horns are similar in length and very short (<40%
of ECL).
Zearaja chilensis is widely distributed in the south-west Atlantic Ocean between
33and 55S, from 25 to 435 m depth, being more abundant between 50 and
150 m depth. In the south-east Pacific Ocean, this fish occurs as far south as 35S
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CHONDRICHTHYAN EGG CASES 1277
(Menni & Stehmann, 2000; Cousseau et al., 2007). Females bearing egg cases were
found in northern Patagonian waters at 50 m depth (Fig. 1). Dipturus trachyderma
occurs in the south-west Atlantic Ocean from southern Brazil to 45S, from 80
to 200 m depth, and in the south-east Pacific Ocean to southern Chile (Menni &
Stehmann, 2000; Cousseau et al., 2007). Females bearing egg cases were found in
central Patagonian waters at 83 m depth (Fig. 1).
Psammobatis
This genus, endemic to South America, comprises eight species, six of which are
present in the Argentine continental shelf: the shortfin sand skate Psammobatis nor-
mani McEachran 1983, the smallthorn sand skate Psammobatis rudis G¨
unther 1870,
the freckled sand skate Psammobatis lentiginosa McEachran 1983, the blotched sand
skate Psammobatis bergi Marini 1932, the zipper sand skate Psammobatis extenta
(Garman 1913) and the spade sand skate Psammobatis rutrum Jordan 1891 (Menni
& Stehmann, 2000; Cousseau et al., 2007; Mabraga˜
na, 2007). Another species (the
smalltail sand skate Psammobatis parvacauda McEachran 1983) has been recorded
in the south-west Atlantic Ocean around the Falkland Islands (McEachran, 1983) but
has never been found in the Argentine continental shelf.
The egg cases (Fig. 12) are small. Cases vary from 25 to 53 mm in length (horns
excluded) and are relatively smooth to the touch but finely striated under magnifica-
tion.
Egg cases of P. bergi [Fig. 12(a)] are smaller than 50 mm in length (horn
excluded) and square shaped. The MAW is >80% of ECL and has a relatively
convex anterior apron edge. The surface of the case is finely striated. The dorsal
surface is covered with a layer of longitudinal fibres, whereas the ventral surface
is naked [Fig. 13(a)]. The LKW is narrow (58% of MAW); the posterior apron is
wider (1·8–4·5 times) than the anterior one. The posterior horns are relatively short
(1·2–1·6 times ECL) but longer (1·4 2 times) than the anterior horns.
The egg cases of P. extenta [Fig. 12(b)] are very small (<31 mm in length), with
MAW c. 59 78% of ECL. The case surface bears fine longitudinal striations and
ornamentation only visible under magnification [Fig. 13(b)]. Attachment fibres are
observed along the lateral keel. The LKW is narrow (57% of MAW). The posterior
apron is wider than the anterior ones (26 times). The posterior horns are relatively
short (0·9–1·45 times ECL) but longer (1·1–2·2 times) than the anterior horns.
The egg cases of P. lentiginosa [Fig. 12(c)] are small (40 mm in length, horn
excluded), with MAW c. 63 71% of ECL. The aHL2 is very small (<40% of ECL)
and the posterior apron edge is slightly concave. The case surface and fibres are
arranged similar to those of P. bergi, and fibres on the dorsal face are fine and
scattered [Fig. 13(c)]. The LKW is narrow (7 8% of MAW) and the posterior apron
is wider (23·3 times) than the anterior ones. The posterior horns are relatively short
(0·9–1·2 times ECL) but longer (1·9–2·0 times) than the anterior horns.
The egg cases of P. normani [Fig. 12(d)] are small (50 mm in length, horn
excluded), with MAW c. 64 73% of ECL. The surface of the case is finely stri-
ated. Attached fibres at both lateral keels are close to each horn. The dorsal surface
is covered by a layer of longitudinal fibres, whereas the ventral surface is naked
[Fig. 13(d)]. A large aHL2 (49–60% of ECL) and a relatively flat posterior apron
are also present. The LKW is narrow (79% of MAW) and the posterior apron is
©2011 The Authors
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1278 E. MABRAGA ˜
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(a) (b) (c)
(d)
(e)
(f)
Fig. 12. Dorsal view of the egg cases of (a) Psammobatis bergi,(b)Psammobatis extenta, (c) Psammobatis
lentiginosa, (d) Psammobatis normani, (e) Psammobatis rutrum and (f) Psammobatis rudis. Scale bar =
1 cm per unit.
wider (3·6 times) than the anterior ones. The posterior horns are relatively short
(1·2–1·6 times ECL) but longer (1·1–2·6 times) than anterior horns.
Psammobatis rutrum [Fig. 12(e)] possess a very small egg case (<30 mm in
length), with MAW c. 73% of ECL. The surface of the case presents fine longitudinal
striations [Fig. 13(e)] and attached fibres along the lateral keel. The LKW is narrow
(7% of MAW). The posterior apron is relatively narrow (10% of ECL) but wider
than the anterior one (1·5 times). The posterior horns are relatively short (1·4 times
ECL) but longer (2·3 times) than anterior horns.
The egg cases of P. rudis [Fig. 12(f)] are small (50 mm in length, horn excluded),
with MAW c. 57 70% of ECL. The capsules have a flange at their posterior end,
©2011 The Authors
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CHONDRICHTHYAN EGG CASES 1279
(a) (b)
(c) (d)
(e) (f)
Fig. 13. Surface of egg cases of species of Psammobatis showing the different patterns (×40).
(a) Psammobatis bergi,(b)Psammobatis extenta, (c) Psammobatis lentiginosa, (d) Psammobatis nor-
mani, (e) Psammobatis rutrum and (f) Psammobatis rudis.
which is characteristic of this species. The aHL2 is short (2248% of ECL). The
surface of the case and pattern of attachment fibres are similar to those found in
P. normani, but the lack of a layer of fibres on the dorsal face distinguishes P. rudis
from the latter [Fig. 13(f)]. The LKW is narrow (8 10% of MAW) and the posterior
apron is wider (2·4 times) than the anterior ones. The posterior horns are relatively
short (0·98–1·6 times ECL) but longer (1·8–3·1 times) than the anterior ones.
Psammobatis rudis and P. normani are widely distributed in the south-west
Atlantic Ocean between 35and 55S, ranging from 49 to 350 m depth, but they are
more abundant between 70 and 180 m depth. In the south-east Pacific Ocean, these
species occur south to 30S (Menni & Stehmann, 2000; Cousseau et al., 2007;
Mabraga˜
na, 2007). Females of P. rudis bearing egg cases were found in Patag-
onian waters (4555S) between 75 and 116 m depth (Fig. 1), whereas those of
P. normani were found throughout the shelf from 71 to 182 m depth (Fig. 1). Psam-
mobatis lentiginosa is distributed in the south-west Atlantic Ocean from 32to 46
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1280 E. MABRAGA ˜
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S, from 49 to 164 m depth, being more abundant from 60 to 120 m depth (Menni
& Stehmann, 2000; Cousseau et al., 2007; Mabraga˜
na, 2007). Females bearing egg
cases were found at 3545S, between 63 and 116 m depth (Fig. 1). Psammobatis
bergi and P. extenta are distributed in the south-west Atlantic Ocean from 23to
45S, and from the coast to 70 m depth, being more abundant between 25 and
66 m (Menni & Stehmann, 2000; Cousseau et al., 2007; Mabraga ˜
na, 2007). Females
bearing egg cases were found in northern Argentina from 25 to 66 m depth (Fig. 1).
Psammobatis rutrum occurs in the south-west Atlantic Ocean from southern Brazil
to 37S, from 51 to 100 m depth, but has been occasionally recorded in the Argen-
tine continental shelf (Menni & Stehmann, 2000; Cousseau et al., 2007; Mabraga˜
na,
2007). A single female bearing an egg case was found in northern Argentina at
100 m depth (Fig. 1).
Rioraja
This is a monospecific endemic genus distributed in temperate coastal waters of
the south-west Atlantic Ocean (Menni & Stehmann, 2000; Cousseau et al., 2007).
The Rio skate Rioraja agassizi (M¨
uller & Henle 1841) has a medium-sized egg
case [Fig. 14(a)], 6168 mm in length (horns excluded); with MAW c. 60– 62% of
ECL. The surface of the case is finely striated without ridges, being smooth to the
touch [Fig. 14(b)]. The dorsal surface is covered with fine longitudinal fibres. The
aHL2 is large (>50% of case length). Egg cases possess silky attachment fibres
placed in the lateral keel close to each horn. The LKW is narrow (68% of ECL).
Both the anterior and posterior horns are relatively straight. The posterior apron is
wider (1·3–2·6 times) than the anterior one. The anterior horns are stout, relatively
long (c. 7789% of ECL) and curving inwards at their tips. The posterior horns taper
to their tips, are moderately short (c. 0·98–1·2 times ECL), and longer (1·1–1·5
times) than the anterior horns.
Rioraja agassizi is a shallow water species distributed in the south-west Atlantic
Ocean from Espirito Santo (20S) south to 42S, from the coast to 150 m depth,
but in the Argentine continental shelf is more abundant at depths <60 m (Menni &
Stehmann, 2000; Cousseau et al., 2007). Females bearing egg cases were found off
northern Argentina from 15 to 27 m depth (Fig. 1).
Sympterygia
This genus comprises four species (McEachran & Dunn, 1998; Compagno, 2005)
endemic to South America. Two of them are distributed in coastal waters of the
south-west Atlantic Ocean: the smallnose fanskate Sympterygia bonapartii M¨
uller
& Henle 1841 and the bignose fanskate Sympterygia acuta Garman 1877 (Menni &
Stehmann, 2000; Cousseau et al., 2007).
The egg cases are small to medium size, 5186 mm in length (horns excluded).
They have long and thread-like posterior horns, a very narrow lateral keel and a
marked lateral keel thickness (>5% of ECL, 1·6–4·8 times LKW) (Fig. 15). The
case surface is smooth and finely striated without ridges (Fig. 16). Attachment fibres
are placed at the end of the posterior horns. The anterior apron border is concave
while the posterior one is nearly straight.
The egg cases of S. bonapartii are medium size (68 86 mm in length), with
MAW c. 59 63% of ECL. The anterior horns curved inwards, flattening towards
©2011 The Authors
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CHONDRICHTHYAN EGG CASES 1281
(a) (b)
Fig. 14. (a) Dorsal view of the egg case of Rioraja agassizi. Scale bar =1 cm per unit. (b) Surface of the
case (×40).
the tips and are c. 5867% of ECL in length. The posterior apron is wider than
anterior apron (1·7–2·2 times). The posterior horns are long (>1·4 times ECL, but
<2·5 times) and c. 2·3–3·2 times the length of the anterior horns.
The egg cases of S. acuta are small (<60 mm in length), with MAW c. 57– 70%
of ECL. The surface of the case is glossy. The anterior horns curve ventrally, and
are flattened and thread-like toward their tips, their length c. 5771% of ECL. The
posterior horns are extremely long (>3 times ECL) and c. 5·3–9·0 times the length
of the anterior ones. The posterior apron is wider (1·3–2·8 times) than the anterior
apron.
Sympterygia acuta is distributed in shallow waters in the south-west Atlantic
Ocean between 22S and 41S, from the coast to 50 m depth (Menni & Stehmann,
2000; Cousseau et al., 2007). Egg cases were collected from females after the adult
specimens had been deposited at the Museo del Mar aquarium. Sympterygia bona-
partii is widely distributed in shallow waters in the south-west Atlantic Ocean from
Rio Grande do Sul to 50S, from 20 to 100 m depth (Menni & Stehmann, 2000;
Cousseau et al., 2007). Females bearing egg cases were found in northern Argentina
from 12 to 49 m depth (Fig. 1).
DISCUSSION
The American endemic catsharks, genus Schroederichthys, are exclusively ovip-
arous and are represented by five species. Egg capsules of the narrowtail catshark
Schroederichthys maculatus Springer 1966, the slender catshark Schroederichthys
tenuis Springer 1966 and the redspotted catshark. Schroederichthys chilensis
(Guichenot 1848) have been previously described (Springer, 1979; Gomes & de Car-
valho, 1995; Hern´
andez et al., 2005). The egg cases of the genus Schroederichthys
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1282 E. MABRAGA ˜
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(a) (b)
Fig. 15. Dorsal view of the egg cases of (a) Sympterygia acuta and (b) Sympterygia bonapartii. Scale bar =
1 cm per unit.
lack the typically coiled anterior tendrils of the family Scyliorhinidae. In S. tenuis,S.
chilensis and Schroederichthys saurisqualus Soto 2001, a couple of anterior filamen-
tous tendrils have been described (Gomes & de Carvalho, 1995; Hern´
andez et al.,
2005). In contrast, anterior tendrils were not found in S. bivius and S. maculatus
(Springer, 1979). Furthermore, in this study the majority of egg capsules have been
laid by females kept in captivity, therefore it has been possible to confirm that S.
bivius has capsules without anterior tendrils. Two species of Scyliorhinus, have been
reported from Uruguayan waters: Scyliorhinus haeckeli (Miranda Rivero 1907) and
Scyliorhinus besnardi Springer & Sadowski 1970. Their egg-laying area, however,
is probably in southern Brazil. They also have cigar-shaped egg cases but with the
anterior and posterior curled tendrils developed (Gomes & de Carvalho, 1995). The
genus Apristurus, the largest within the family Scyliorhinidae, comprises at least
three distinct species groups, the Apristurus brunneus (Gilbert 1892) group, Apris-
turus longicephalus Nakaya 1975 group and Apristurus spongiceps (Gilbert 1905)
group (Nakaya et al., 1999; Igl´
esias et al., 2005; Flammang et al., 2007). Similarity
of egg case morphology in species of Schroederichthys and the A. brunneus and A.
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CHONDRICHTHYAN EGG CASES 1283
(a)
(b)
Fig. 16. Surface of egg cases of (a) Sympterygia acuta and (b) Sympterygia bonapartii (×40).
longicephalus groups suggest a similar oviposition strategy. In contrast, the lack of
egg-case tendrils of the A. spongiceps group of catsharks suggests an evolutionary
divergence (Flammang et al., 2007). In vivo observations show that egg-case ten-
drils of the A. brunneus and A. longicephalus groups were wrapped around sedentary
organisms.
©2011 The Authors
Journal of Fish Biology ©2011 The Fisheries Society of the British Isles, Journal of Fish Biology 2011, 79, 1261 1290
1284 E. MABRAGA ˜
NA ET AL.
The egg case morphology of C. callorynchus is similar to those of the other two
described species of the genus, the cape elephantfish Callorhinchus capensis Dum ´
eril
1865 and the ghost shark Callorhinchus milii Bory de Saint-Vincent 1823 (Smith &
Griffiths, 1997; Hamlett, 2005) The zig-zig pattern observed in the capsule surface
of C. callorynchus is unique among chondrichthyans. Unfortunately, the description
of egg case surfaces of other species of Callorhinchus is lacking.
Despite the high diversity and distribution of skates, comparative studies of their
egg cases are scarce and restricted to Japanese waters and the Bering Sea (Ishiyama,
1958; Ebert, 2005; Ebert & Davis, 2007). In the northern hemisphere, egg cases of
Bathyraja have been studied in detail since the middle of the last century (Ishiyama,
1958; Ishiyama & Ishihara, 1977; Ishiyama & Ishihara, 1985; Stehmann & Merrett,
2001; Ebert, 2005; Ebert & Davis, 2007). Egg cases in the south-west Atlantic Ocean
are very similar to those of the northern hemisphere. Although Bathyraja shows a
high species diversity, with wide distribution ranges (McEachran & Miyake, 1990)
the egg cases have a very conservative morphology, with typically strongly curved
posterior horns. Orlov & Biryukov (2005) suggest that this characteristic feature
probably facilitates the egg emergence from the cloaca.
In the worldwide genus Dipturus, two distinct forms of capsules were described.
Dipturus trachyderma possesses the largest egg case (222– 230 mm) and an unusual
case morphology according to the analyses made here. The egg case has well-
developed aprons and lateral keel, matching with those of other species from the
northern hemisphere, such as the giant skate Dipturus gigas (Ishiyama 1958)
(235 mm) and the longnosed skate Dipturus oxyrinchus (L. 1758) (140 –235 mm)
(Ishiyama, 1958; Bor, 2006), and those from Australian waters for instance, the
wedgenose skate Dipturus whitleyi (Iredale 1938) (220 mm) (Treloar et al., 2006).
The other type of capsule morphology in Dipturus (as shown by Z. chilensis) cor-
responds to an egg case typically shaped without a developed lateral keel and an
anterior apron, similar to other conspecific dipturids (Bor, 2006). Treloar et al. (2006)
described the capsules of several species of Dipturus showing a varied morphol-
ogy, these included the thornback skate Dipturus lemprieri (Richardson 1845) and
Dipturus sp. B (=D. canutus) similar to Z. chilensis.
With regard to species identification based on the external morphological features,
the endemic genus Psammobatis is the most problematic; in contrast, species identi-
fication by egg case characters is less problematic. This genus possesses the smallest
egg case among worldwide skates: P. rutrum has capsules that reach c. 30 mm length
(Bor, 2006). The features of the capsules of the raspthorn sandskate Psammobatis
scobina (Philippi 1857) (Concha et al., 2009) are coincident with those (described
here) of P. normani.
The genus Sympterygia has the largest posterior horn compared to other skates.
Oddone & Vooren (2002) found capsules of S. acuta with posterior horns of 440 mm
in length. Egg cases of S. acuta and S. bonapartii are commonly found on sandy
beaches of the Buenos Aires coast, frequently attached to the debris. Long tendrils
may help to secure the egg case with some form of substratum (Flammang et al.,
2007). The coasts of southern Brazil, Uruguay and northern Argentina generally lack
hard bottom substrata and appropriate sea-floor vegetation for the attachment of egg
cases. Flammang et al. (2007) have established that these are the reasons for the
development of extremely long horns with silky fibres in these species. The absence
of hard substrata could be a pressure for the development of long tendrils, which may
©2011 The Authors
Journal of Fish Biology ©2011 The Fisheries Society of the British Isles, Journal of Fish Biology 2011, 79, 1261 1290
CHONDRICHTHYAN EGG CASES 1285
help to secure anchorage with other capsules and then make them difficult to remove
from the spawning site. This characteristic (an extremely long posterior horn) feature
was also observed in the egg cases of an Australasian skate of the genus Pavoraja
(Treloar et al., 2006). Capsules of Sympterygia, however, also possess a marked
thickening of the lateral keel, which is a feature not observed in species of Pavoraja
or any other species.
Egg cases of A. doellojuradoi possess a remarkable lateral keel extending the
length of the case and tapering off along outer edge of horns. The anterior end of the
horn finishes abruptly, whereas its posterior end tapers progressively. These char-
acteristics were also observed in A.cf. hyperborea from Australian waters (Treloar
et al., 2006) and in an unidentified deep-sea egg case from the eastern North Pacific
Ocean (Ebert & Davis, 2007). The latter specimen was called an ‘unidentified deep-
sea skate egg case B’, because it was collected from benthic samples and not from
a female uterus. Ebert & Davis (2007) explained that a female of the broad skate
Amblyraja badia (Garman 1899) was observed swimming in the vicinity of where
these egg cases were collected. As A. badia is the only species of Amblyraja reported
for the eastern North Pacific Ocean, these egg cases probably correspond to this
species. Morphologically, capsules of the three species are very similar, with that of
A. doellojuradoi being the smallest. This is unsurprising given that A. doellojuradoi
is the smallest species of the genus reaching at least 600 mm total length (LT),
whereas A. badia and A. hyperborea reach c. 1000 mm LT.
The foregoing description of egg cases of Rioraja and Atlantoraja species are
consistent with those made previously for Brazilian waters (Oddone et al., 2006).
As egg cases can be a useful tool for identifying chondrichthyan species, a provi-
sional key to the south-western Atlantic Ocean chondrichthyan egg cases is presented
here.
IDENTIFICATION KEY FOR CHONDRICHTHYAN EGG CASES OF THE
SOUTH-WEST ATLANTIC OCEAN
1a. Spindle-shaped egg case, with anterior and posterior tubular extensions and
lateral flanges, and without horns or tendrils .................. Callorhinchus
callorynchus
1b. Egg case not spindle shaped, horns or tendrils on one or both ends ..........2
2a. Cigar-shaped egg case with tendrils ..................................... 3
2b. Rectangular egg case with anterior and posterior horns .....................4
3a. Egg case with posterior curled tendrils ..................... Schroederichthys
bivius
3b. Egg case with anterior and posterior curled tendrils ......... Scyliorhinus spp.
Remarks: Two species of Scyliorhinus have been reported for Uruguayan waters
(see references in text), but probably their egg-laying area is in southern Brazil.
Capsules characteristics were taken from Gomes & de Carvalho (1995) and Bor
(2006).
©2011 The Authors
Journal of Fish Biology ©2011 The Fisheries Society of the British Isles, Journal of Fish Biology 2011, 79, 1261 1290
1286 E. MABRAGA ˜
NA ET AL.
4a. Egg case length (ECL) >110 mm; well-developed posterior apron (>30% of
ECL); dorsal and ventral surfaces of case covered with dense woven-like fibers;
surface of the case beneath the fibrous layer relatively smooth, finely striated
and without ridges ...................................Dipturus and Zearaja
4b. The ECL <110 mm; posterior apron narrow or moderately developed (<30% of
ECL); only the dorsal surface of case covered with dense woven-like fibres, or
surface without these woven-like fibres ...................................6
5a. The ECL >200 mm, lateral keel >20 mm .................. D. trachyderma
5b. The ECL <170 mm, lateral keel <20 mm ....................Z. chilensis
Remark: Other species of Dipturus could be found in the Argentine continental
shelf (see references in text), whose egg cases have not been observed.
6a. Posterior horns thread-like, their length >1·4 times case length, lateral keel
thickness >1·6 times lateral keel width ......................Sympterygia 7
6b. Posterior horns progressively thinner, of different lengths, lateral keel thickness
up to one time lateral keel width .........................................8
7a. The ECL >65 mm, posterior horns long, <2·5 times case length............
............................................................. S. bonapartii
7b. The ECL <60 mm, posterior horns very long, >3·5 times case length .......
................................................................ S. acuta
8a. The ECL <60 mm ........................................ Psammobatis 9
8b. The ECL >60 mm ....................................................14
9a. The ECL 31 mm .................................................... 10
9b. The ECL >34 mm .................................................... 11
10a. Posterior apron more than twice anterior apron width ......... P. extenta
10b. Posterior apron less than twice anterior apron width ............ P. rutrum
11a. Square-shaped case, case width >80% of ECL, anterior apron straight or
slightly convex ...................................................P. bergi
11b. Rectangular-shaped case, case width <75% of ECL, anterior apron concave
...................................................................... 12
12a. The ECL 40 mm, anterior horn straight distance <20 mm . ....P. lentiginosa
12b. The ECL >40 mm, anterior horn straight distance >20 mm ............... 13
13a. Posterior apron with a flange, anterior horn straight distance <50% of case
length ........................................................... P. rudis
13b. Posterior apron without a flange, anterior horn straight distance generally >50%
(4960%) of ECL ............................................P. normani
©2011 The Authors
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CHONDRICHTHYAN EGG CASES 1287
14a. Posterior horns strongly curved towards the inside, making a semicircle, surface
of case rough or relatively smooth ............................. Bathyraja 15
14b. Posterior horns straight or slightly curved ................................ 18
15a. Lateral keel thickness >2mm...........................................16
15b. Lateral keel thickness <2mm..........................................17
16a. The ECL >90 mm, maximum width >50 mm, surface of case with longitudinal
striation with long and thin prickles of different size, giving a velvety texture
to the touch .............................................. B. albomaculata
16b. The ECL <90 mm, maximum width <50 mm, egg case surface texture coarse
and very rough to the touch, covered by papillose longitudinal ridges; prickles
with different sizes and shapes ..............................B. macloviana
17a. Lateral keel somewhat light, 6 mm; surface of case with longitudinal striation
with long and thin prickles of similar size, posterior horns longer than anteriors,
the lateral keel width (LKW) is relatively broad, 1216% of the maximum egg
case width (MAW) .......................................B. magellanica
17b. Lateral keel somewhat dark, 6 mm; egg case surface is relatively smooth,
finely striated, with rasp-like denticles and without prickles; LKW relatively
narrow (611% of MAW) .................................B. brachyurops
Remark: Other four species of the genus are present in the Argentine continental
shelf where egg cases have not been observed. Possibly adult females lay its
capsules at depth furthermore the continental slope.
18a. Anterior horn straight distance >50% of ECL, with attachment fibres displayed
in the lateral keel next to each horn .........................Rioraja agassizi
18b. Anterior horn straight distance <50% of ECL, if it is greater, ECL is always
>90 mm, attachment fibres absents or displayed in a different way ..........19
19a. Posterior horns very large, longer than case length, lateral keel tapering progres-
sively to anterior horns .....................................Atlantoraja 20
19b. Posterior horns shorter than ECL, lateral keel tapering abruptly in anterior horns
......................................................... A. doellojuradoi
20a. The ECL >95 mm, dorsal surface with woven-like fibres; surface of case
beneath fibrous layer finely striated without ridges .............. A. castelnaui
20b. The ECL <80 mm, without woven-like fibres; surface of case longitudinally
and uniformly striated with marked ridges especially on dorsal face .. ........21
21a. Posterior horns long, their length <1·5 times ECL; MAW <60% of ECL
........................................................... A. cyclophora
21b. Posterior horns very long, their length >1·5 times ECL; MAW >60% of ECL
..............................................................A. platana
©2011 The Authors
Journal of Fish Biology ©2011 The Fisheries Society of the British Isles, Journal of Fish Biology 2011, 79, 1261 1290
1288 E. MABRAGA ˜
NA ET AL.
We thank the skippers, crews and scientists of the R.V. O. Balda and R.V. E. L. Holmberg
from the Instituto Nacional de Investigaci´
on y Desarrollo Pesquero for their assistance in the
collection of samples. We also thank C. Bremec for the assistance in obtaining capsules from
benthos campaigns, L. Lucifora for comparative material, Museo del Mar for taking samples
from captive specimens and C. Milloc and M. Farenga for providing technical assistance. We
would like to thank anonymous reviewers and I. Harrison for offering helpful comments that
improved the earlier drafts of the manuscript. This research was partially supported by grants
of FONCYT (PICT 2007 02200), CONICET (PIP 0942) and UNMdP (EXA 490/10). L.B.S.
and G.D. were supported by scholarships from CONICET.
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©2011 The Authors
Journal of Fish Biology ©2011 The Fisheries Society of the British Isles, Journal of Fish Biology 2011, 79, 1261 1290
... Clasper description followed Hulley [62], Leible and Stehmann [63], Leible [64] and Menni [65]. Egg cases (14 from Argentina and 2 from Chile) were measured following Mabragañ a et al. [66]. ...
... Raia stabuliforis: [76] [misidentification], Raia brevicaudata [77], Raja flavirostris: [10,[80][81][82], Raja (Dipturus) flavirostris: [39,43,44], Dipturus flavirostris: [12], Dipturus chilensis: [15,77,[83][84][85][86][87], Zearaja chilensis: [5] [in part]; [35] [in part]; [47,66,88], Zearaja flavirostris: [49,52,89]. ...
... Egg-cases morphology is also species-specific [66,[95][96][97][98][99]. Egg cases of Z. brevicaudata have a thinner lateral keel than those of Z. chilensis. ...
Article
Zearaja chilensis has been reported from Southern Brazil in the Southwest Atlantic (SWA) to northern Chile in the Southeast Pacific (SEP), and it was listed as vulnerable by the IUCN. Recent molecular studies have called into question the conspecificity between specimens from these opposite coasts of South America, which can have implications for the conservation status of the species. To verify the identity of specimens identified as Z. chilensis, 47 individuals from SWA and 22 from SEP were examined. By comparing external morphology, spinulation pattern, clasper, egg cases, and mitochondrial cytochrome c oxidase I (COI) sequence data, differences between groups were found. Adults from SWA presented longer snout length and shorter tail than those from SEP. Dermal denticles were restricted to the rostral area in SWA skates, whereas in SEP skates most of the dorsal surface was covered with denticles. Marked differences in the morphology of several components of clasper were noticeable. Egg cases of SWA skates had thinner lateral keels than those of SEP. Molecular analysis revealed two well-defined cohesive clusters, corresponding to SWA and SEP specimens, respectively. Average K2P distance between groups was 3.4%, higher than expected for intraspecific differences, and sequences were assigned to different BINs. These integrative approaches strongly support that specimens from SWA known as Z. chilensis correspond to a different nominal species than those from SEP. Herein, Z. brevicaudata (Marini 1933) is resurrected from synonymy with Z. chilensis.
... This catshark is a common by-catch species in Patagonian coastal trawl fisheries in the south-west Atlantic Ocean (Van der Molen et al., 1998) and also in the shelf-break area on the Patagonian scallop fishing grounds (Schejter et al., 2012). As in skates (Rajiformes), S. bivius is oviparous and lays its eggs in a protective leathery cigar-shaped egg case, which has a convex anterior end without tendrils and a posterior end with long, filamentous and coiled tendrils (Mabragaña et al., 2011). The presence of egg cases of S. bivius in the south-west Atlantic Ocean associated with several benthic organisms is reported here. ...
... Egg cases of S. bivius examined here did not show anterior horns, had coiled tendrils at the posterior end and very long, silky attachment fibres near the anterior border. This description adds new information to the morphology of S. bivius egg cases, since fibres had not previously been recorded by Mabragaña et al. (2011). The presence of these structures is associated with habitats where the eggs can be firmly anchored, such as those with corals, sponges and tubeworms. ...
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Egg cases of the narrowmouthed catshark Schroederichthys bivius were recorded entangled with sponges, corals and tubeworms at different sites in the south-west Atlantic Ocean. This work sheds light on the importance of benthic invertebrates in the life cycle of oviparous chondrichthyan species.
... Egg capsules were described and measured based on previous studies (Ebert and Davis 2007;Concha et al. 2009;Mabragaña et al. 2011;Soto-López et al. 2020). Morphological characteristics such as color, texture, capsule shape, lateral and ventral description of the capsule (i.e., asymmetric, symmetric, convex, flat, striated, smooth, glossy), and thickness and shape of the horns were considered. ...
Article
Nine egg capsules of the Rasptail Skate (Rostroraja velezi) were collected from their southernmost distributional range in northern Peruvian waters for their description. Egg capsules had a glossy black or dark brown color, with a subrectangular shape, slightly wider at posterior end than at anterior end. Egg capsules when observed under a stereoscope revealed a finely striated surface. Egg capsules ranged from 6.8 to 7.7 cm in length, 4.9 to 6.2 cm in maximum width, and 4.2 to 5.9 cm in minimum width. Anterior horn length was shorter than posterior horn length (0.29% vs. 0.58%). Differences in egg capsule surface and size were observed when compared to capsules of R. velezi from Baja California, Mexico, possibly due to differences in environmental conditions since individuals sampled belong to different marine provinces. Our results represent the second study to describe egg capsules for this species and the first in the Tropical Eastern Pacific marine province.
... Alcançam até 32 cm de comprimento e os machos atingem maturidade sexual entre 23 e 27 cm. São ovíparas e depositam ovos pequenos (<30 mm) (Mabragaña et al., 2011;Last et al., 2016;Martins & Oddone, 2017). Alimentam-se predominantemente de crustáceos e ocasionalmente de peixes e poliquetos (Viana, Valentin & Vianna, 2017). ...
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A externalização de órgãos internos em peixes tem sido registrada ao longo do tempo na literatura científica. Grande parte dos registros está relacionada à eversão ou protrusão do estômago e/ou intestino, devido principalmente ao barotrauma. Porém uma pequena parcela dos registros é referente a diversas causas naturais. O presente estudo teve como objetivo registrar a ocorrência de um raro evento de eversão vaginal na raia anã espinhosa Psammobatis rutrum. Em 15/06/2020 três exemplares (2 fêmeas e 1 macho) foram capturados como fauna acompanhante da pesca de parelha nas proximidades da Barra de Santos SP, com profundidade média de 27 metros. Dentre eles, uma exemplar fêmea apresentava uma protrusão via abertura cloacal. Através de necropsia, avaliação comparativa e estudo das vias reprodutivas foi identificado que o órgão externalizado era a parede vaginal. Embora existam muitos registros de externalização de órgãos de Elasmobranchii, principalmente relacionados ao comportamento natural de eversão do estômago e intestino, apenas um registro deste tipo de evento foi reportado para órgão reprodutivo. Não foi possível identificar a causa da eversão vaginal, porém tal evento está associado a um quadro de prolapso pélvico, que pode ter sido intensificado por causas naturais ou devido a captura.
... Each egg case was measured following the methodology of Mabragaña et al. (2011). The measurements performed were T L (excluding the tendril), maximum width, minimum width, length of the anterior horns, length of the anterior tendril, length of the posterior tendril, lateral keel width, anterior apron, posterior apron and columella (i.e., straight distance from the anterior apron to the apex of the anterior horn). ...
Article
The Cephaloscyllium ventriosum shark is present in the artisanal fisheries of elasmobranchs on the western coast of Baja California Sur, Mexico. The main characteristics of the sexual maturation of this species based on individuals captured from off the northwest Mexico in 2013‐2016 are described.The size at maturity of this species was determined for the first time (total length 82 cm for females and 76 cm for males). Most of females had one egg case per one uterus, and two per one uterus is an isolated event of low incidence. From the histological analysis of females, it was possible to show sperm storage in the oviducal gland. Fully developed sperm in immature organisms were identified in the testes. Therefore, the main indicator of the maturity stage of males and their mating activity is the clasper. The present study provides evidence for a reliable estimation of the sexual maturity of these organisms, demonstrating the need for the combination of macroscopic and microscopic methods. This article is protected by copyright. All rights reserved.
... The taxonomic use of egg cases has been well documented and many authors have described the morphology of the egg cases by providing useful working tools (e.g. Clark 1922Clark , 1926Springer 1939;Ishiyama 1958;Cox 1963;Hitz 1964;Templeman 1982;Koob & Summers 1996;Howard 2002Howard , 2017Iglesias et al. 2002;Ebert 2005;Ebert et al. 2006Ebert et al. , 2008Treloar et al. 2006;Ebert & Davis 2007;Stevenson et al. 2007;Mabragaña et al. 2009Mabragaña et al. , 2011Concha et al. 2012;Ishihara et al. 2012;Maia et al. 2015;Bor 2016;Gordon et al. 2016;Porcu et al. 2017). ...
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Chondrichthyan egg cases are important elements for species-specific identification and also provide a valuable aid in determining a species spatial distribution, as well as for defining spawning areas. Considering the absence of a general key for the identification of the egg cases of the Mediterranean Chondrichthyes, this work aims to fill this gap by presenting a species-specific key based on morphological features of the egg case. The key was developed primarily analysing fresh egg cases dissected from the oviduct, egg cases collected from the seabed or found dried lying on the seashore, after species confirmation by DNA analysis. Original data were integrated with information scrutinized from literature. In order to improve species identification, a protocol for the standardized acquisition of morpho-biometric and meristic features is also provided as a prerequisite for the appropriate use of the identification key. The total width and length included the horns, when they are not broken, are the parameters that best explain the assignment of the egg case to a specific species.
... According to this study, P. rutrum has the smallest egg capsule in the genus Psammobatis. Mabragaña et al. (2011) reported egg capsules collected in Argentinean waters with a maximum L EC = 3 cm, whereas this study recorded 2·62 cm as the maximum L EC . Posterior horn length was also larger in Argentinean waters than in southern Brazil. ...
Article
The Rasptail skate Rostroraja velezi is commercially exploited in artisanal elasmobranch fisheries along the west coast of Baja California Sur, Mexico, but information on its life history is limited. This study aimed to investigate the reproductive biology of R. velezi. A total of 105 specimens were caught from April 2008 to May 2012, including the largest reported specimen with 121 cm total length, 96 cm disc width (DW). Females attained larger sizes than males. Males and females presented functional gonads. There was an asymmetry in the testes of males, with the left testis being larger. Histological analysis of the reproductive biology of R. velezi was performed here for the first time. The presence of sperm storage in females, and spermatogenic development beginning at the first stages of maturity in males was recorded. It was possible to identify the development of secretions in the club, baffle, and terminal zone of the oviducal gland. DW at maturity, defined as the DW at which 50% of the population is mature, was estimated at 68–72 cm for females and 65.1 cm for males. Egg‐bearing females caught in April and May presented one egg capsule per uterus. Furthermore, a description of the egg capsule of R. velezi is provided. Elucidating the reproductive cycle, the type of reproductive strategies, and the fecundity of R. velezi will allow us to understand the impact of fisheries on this species.
... The latter was described based on a single female collected around Malvinas/Falkland Islands, whose external morphological characteristics and skeletal structures, particularly the scapulocoracoid, were unique (McEachran, 1983). After the revision of McEachran (1983), several studies were conducted on almost all Psammobatis species including reproductive biology (Braccini and Chiaramonte, 2002b;Mabragaña and Cousseau, 2004;San Martín et al., 2005, Mabragaña, 2007Perier et al., 2011;Mabragaña et al., 2012;Martins and Oddone, 2017), feeding ecology (Braccini and Perez, 2005;Mabragaña, 2007;Mabragaña and Giberto, 2007;San Martín et al., 2007;Barbini and Lucifora, 2012), morphology (Braccini and Chiaramonte, 2002a;Mabragaña, 2007), egg cases (Concha et al., 2009;Mabragaña et al., 2011;Vazquez et al., 2016), and their parasites community (Irigoitia et al., 2019). Strikingly, no further studies were conducted in P. parvacauda. ...
Article
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Skeletal structures, especially the claspers, neurocrania, and scapulocoracoids have been widely used to characterize and describe new species of elasmobranchs. Intra and interspecific variation of scapulocoracoids in 3 species of Psammobatis (n = 94) from the Southwest Atlantic Ocean were analyzed to assess its utility as a diagnostic character in skates. Moreover, based on scapulocoracoids and body morphometric analyses, the validity of Psammobatis parvacauda McEachran, 1983 was evaluated. A remarkable sexual dimorphism in scapulocoracoids was observed in all species in accordance with original descriptions, which was also evident in the principal component (PCA) and Discriminant Analyses. The number and arrangement of post-dorsal and post-ventral fenestra were highly variable at intra-specific level, in contrast with original descriptions. Particularly, one of the morphotypes observed in females of P. normani was identical to the one reported in P. parvacauda. Results showed intraspecific variation in this structure, as was previously observed in Sympterygia species. Therefore, this structure should not be used as a diagnostic character in skates, at least for these genera. Regarding body morphometry the PCA showed that P. parvacauda grouped with P. normani females and the cross-validated analysis showed that P. parvacauda was classified in the group of P. normani females. P. parvacauda is only known from its original description (one female) and a likely second specimen, but our analyses revealed a lack of diagnostic characteristics. Based on observations and measurements of the holotype of P. parvacauda, and comparisons with congenerics, P. normani is regarded a senior synonym of P. parvacauda.
... For egg case measurement, the length was recorded as the distance between the anterior and posterior ends, excluding the horns, and width was recorded as the maximum distance between the lateral margins of the case. Nomenclature of egg case anatomy was based on Mabragaña et al. (2011). Reproductive parameters recorded for captive-born females were compared with those previously recorded for the wild-caught progenitor skates by means of Mann-Whitney U test. ...
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We analyzed growth and reproduction of captive-born smallnose fanskates Sympterygia bonapartii. Egg cases were obtained from oviposition of two females caught in the wild and held at Temaikèn Aquarium. Following hatching, growth was analyzed in 13 females and 21 males until sexual maturity. Pattern of oviposition activity and reproductive performance were evaluated in six of the captive-reared females. Four models were fitted to growth data, among which the logistic function was the one attaining the best fit. The highest growth rate for both sexes was recorded during the first year of life, whereas growth was significantly higher in females than in males during the second year. Size at first oviposition was 61.7 ± 3.5 cm TL, similar to wild specimens. However, captive-reared females reached maturity before two years of age, i.e. much earlier than wild skates, implying a significant phenotypic plasticity in this species. The similarity in size at maturity and the difference in age at maturity between captive and wild specimens indicate that there is a decoupling of both parameters mediated through growth rates. Captive-born skates reproduced successfully and yielded viable offspring, indicating that the environment at Temaikèn Aquarium is suitable for S. bonapartii to attain its full life cycle.
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In shark populations, variation in sexual size dimorphism (SSD) appears to be related with the reproductive mode. Here, we aimed to investigate the reproductive biology of the narrowmouth catshark Schroederichthys bivius, an oviparous shark with size and secondary sexual dimorphism. For this purpose, specimens were collected during research surveys covering almost their entire distribution in the southwestern Atlantic continental shelf. Size distribution ranged from 196 to 810 mm total length (TL) in males and from 258 to 630 mm TL in females, and the mean size at maturity was 563 mm TL for males and 485 mm TL for females. Males appeared to be capable of mating all times of the year, while females could exhibit an annual reproductive cycle. Besides SSD, with males attaining higher maximum TL and size at maturity, spatial sexual segregation appears to be observed in mature specimens. Although differences in size at maturity were observed between surveys, these differences did not show a latitudinal pattern. The spatial overlap observed between closed areas to trawling and the distribution of egg-bearing females suggests that these closed areas, although designed and established to protect other species, may represent an important measure also for the conservation of S. bivius.
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A new species of Dipturus is described from ten specimens collected off Patagonia, Argentina. Morphological and molecular approaches were used to compare among specimens of recognized Dipturus species. By comparing morphometric, meristic and mitochondrial cytochrome c oxidase I (COI) sequence data, specimens referred to as longnose skate and originally regarded as D. chilensis were shown to be a discrete species as distinguished from both the Yellownose skate, D. chilensis and the Roughskin skate, D. trachyderma. Dipturus argentinensis n. sp. can be distinguished from all other southwestern Atlantic longnose skate species by its color pattern, lack of squamation on both upper and lower surfaces of the disc, and a long, thin tail that is approximately half the total length. The new species has one median row of 10 to 24 small caudal thorns, one or two interdorsal thorns and 35 to 40, and 34 to 43 tooth rows on upper and lower jaws, respectively. The 648 base pair COI mitochondrial DNA “barcodes” derived from specimens of D. argentinensis are identical to each other and exhibit greater than 3% sequence divergence from all other Dipturus species similarly characterized to date. Taken together, these independent morphological and molecular observations serve to corroborate one another and thus provide strong evidence for the recognition of D. argentinensis as a new species.
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Five new species of skates.Bathyraja caeluronigricans, B.notoroensis.B.mactrlata. B.lindbergi, and B.minispinosa were described from the western North Pacific.Bathyraja matsubarai (Ishiyama, 1952) was revised and redescribed.not only because this species is closely related to the above species hut because one of the paratvpes of this species was newly erected as B.notoroensis.Relationships of the six species were discussed morphologically and zoogeographically .
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Egg cases for 10 of 11 valid skate species known to occur in the eastern North Pacific (ENP) were identified and are here described. In addition, egg cases of two unidentified skate species were collected from very deep water off central and southern California, USA. Examples of egg cases for all species, except for two, were removed in utero in order to confirm their species specific identification. The egg cases of seven skate species, including egg cases from the two unidentified species, have not previously been described or illustrated from this region. Previous attempts to identify skate egg cases with their associated species have been inadequate. The ENP skate egg cases can broadly be classified into two main groups: those with broad lateral keels (> 10% maximum egg case width) and those with narrow lateral keels (< 10% maximum egg case width). Egg cases in the former group (with broad lateral keels) generally have a finely striated surface texture that is smooth to the touch. Those in the latter group (with narrow lateral keels), with one exception, tend to have a coarse surface texture, often with prickles, and are rough to the touch. A revised key to the skate egg cases from the ENP is provided.
Article
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Egg cases for 10 of 11 valid skate species known to occur in the eastern North Pacific (ENP) were identified and are here described. In addition, egg cases of two unidentified skate species were collected from very deep water off central and southern California, USA. Examples of egg cases for all species, except for two, were removed in utero in order to confirm their species specific identification. The egg cases of seven skate species, including egg cases from the two unidentified species, have not previously been described or illustrated from this region. Previous attempts to identify skate egg cases with their associated species have been inadequate. The ENP skate egg cases can broadly be classified into two main groups: those with broad lateral keels (> 10% maximum egg case width) and those with narrow lateral keels (< 10% maximum egg case width). Egg cases in the former group (with broad lateral keels) generally have a finely striated surface texture that is smooth to the touch. Those in the latter group (with narrow lateral keels), with one exception, tend to have a coarse surface texture, often with prickles, and are rough to the touch. A revised key to the skate egg cases from the ENP is provided.
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Egg capsules of Atlantoraja cyclophora and A. platana are asymmetrical, dorsally convex and ventrally flat, with longitudinally striated faces. Those of other rajoid genera occurring in Cassino Beach ( Rio Grande do Sul State, Brazil), Psammobatis, Sympterygia and Rioraja, are equally convex in lateral view, and have smooth faces. In Atlantoraja the egg capsules are laterally keeled while in Sympterygia a lateral flange exists. Mean egg capsule length and width are 68 and 39 mm in A. cyclophora, and 69 and 45 mm in A. platana. Egg capsules of A. platana are significantly wider than those of A. cyclophora with anterior and posterior horns significantly longer. The outline of the velum is convex in dorsal view in A. cyclophora and slightly convex in A. platana.
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En diciembre de 2005 se recolectaron cápsulas ovígeras de dos hembras de Psammobatis scobina, capturadas en Caleta Montemar, Chile central (32º57’S-71º33’W). La superficie de las cápsulas fue suave y finamente estriada, de color café y translúcida. Además presentaron la típica forma de barril. La longitud central fluctuó entre 35,25 mm y 38,45 mm y su ancho varió entre 25,91 mm y 27,94 mm. La cara dorsal es convexa con respecto a la ventral. Los cuernos anteriores son más cortos que los posteriores, se orientan hacia el interior y se estrechan hasta adquirir forma de zarcillos hacia las puntas. Los zarcillos laterales resultaron ser un carácter diagnóstico entre especies del mismo género en Chile. Esta es la primera descripción de las cápsulas ovígeras de P. scobina, especie endémica para las costas del sur de Sudamérica.
Article
Egg capsules of Atlantoraja cyclophora and A. platana are asymmetrical, dorsally convex and ventrally flat, with longitudinally striated faces. Those of other rajoid genera occurring in Cassino Beach (Rio Grande do Sul State, Brazil), Psammobatis, Sympterygia and Rioraja, are equally convex in lateral view, and have smooth faces. In Atlantoraja the egg capsules are laterally keeled while in Sympterygia a lateral flange exists. Mean egg capsule length and width are 68 and 39 mm in A. cyclophora, and 69 and 45 mm in A. platana. Egg capsules of A. platana are significantly wider than those of A. cyclophora with anterior and posterior horns significantly longer. The outline of the velum is convex in dorsal view in A. cyclophora and slightly convex in A. platana.
Article
A new species of rajin skate, Zearaja maugeana sp. nov., is described on the basis of specimens from two estuaries in remote southwestern Tasmania. The species, known locally as the Maugean Skate, has been assessed as Endangered in the IUCN Red List of Threatened Animals based on its rarity and very narrow geographic range. It is also one of the few skates worldwide to occur mainly in brackish water. The Maugean Skate belongs to a group of anatomically conservative, Dipturus-like skates conforming to the currently unrecognized genus Zearaja Whitley. This ancient group, with a Gondwanan lineage possibly dating back to the Cretaceous, contains at least two other species: Z. nasuta from New Zealand and Z. chilensis from South America. The skeletal morphologies of the Zearaja species are compared with typical Dipturus skates and their phylogenetic position discussed.
Article
Resumen Available published and unpublished information on the distribution , environment and biology of batoid fishes occurring off Brazil, Uruguay and Argentina is summarized and reviewed for sixty species. Zoogeographic provinces proposed by Lopez (1963, 1964) are considered an adequate framework to define the distribution of these species. The Magellanic fauna, which includes the Pacific Ocean coast off Chile, is a well-defined biological unit. Conversely, the northern fauna changes gradually from the temperate Bonaerensean District off northern Argentina, Uruguay and southern Brazil, to a subtropical and tropical fauna along most of the Brazilian coast. The more drastic change to a truly tropical fauna occurs off French Guiana and Surinam. Within the area studied, rajids are the dominant batoid family, with a large number of rhinobatids and myliobatoids to the north. A more detailed cluster analysis (Jaccard) of batoid distribution patterns, results in nine groups largely corresponding with biological and distributional information: Group I of Magellanic species, Group II of three Magellanic species extending into the Bonaerensean District, a small Group III formed by the deep water skates Bathyraja schroederi, Amblyraja frerichsi and Dasyatis cf. pastinaca, another small Group IV of species with uncommon distributions, Group V of Bonaerensean species, Group VI of relatively rare deep water species, Group VII of northern migrants into the Bonaerensean District, Group VIII of Brazilian species occurring in both the South Brazilian and Brazilian districts, and a completely different Group IX of Northern Brazilian species with their southern distributional limit usually at Rio de Janeiro. A large amount of information is available on many of the species, regarding depth and temperature of occurrence, patterns of distribution, and in many cases reproduction and feeding. Preliminary evaluations of abundance have been obtained for a few species only, but the risk of overfishing is clearly documented for some of them. An odd taxonomic - geographic situation is the status of D. cf. pastinaca, and a peculiar type of cloacal gestation has been described for Benthobatis (similar to that in Squatina). Studies at community ecology level are discussed and full references provided, including many reports only published as meeting summaries.