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received: 2020-09-09                 DOI 10.19233/ASHN.2020.23
LEUCISTIC PIEBALD STRIPED PANRAY, ZANOBATUS SCHOENLEINII 
(CHONDRICHTHYES: ZANOBATIDAE), FROM THE COAST OF SENEGAL 
(EASTERN TROPICAL ATLANTIC)
Christian CAPAPÉ
Laboratoire d’Ichtyologie, Université de Montpellier, case 104, 34095 Montpellier cedex 5, France
e-mail: capape@univ-montp2.fr
Youssouph DIATTA & Almamy DIABY
Laboratoire de Biologie marine, Institut fondamental d’Afrique noire, (IFAN Ch. A. Diop), Université Cheikh Anta Diop de Dakar, 
BP 206, Dakar, Senegal
Sihem RAFRAFI-NOUIRA
Université de Carthage, Unité de Recherches Exploitation des Milieux aquatiques, Institut Supérieur de Pêche et d’Aquaculture de Bizerte, 
BP 15, 7080 Menzel Jemil, Tunisia
Christian REYNAUD
Laboratoire Interdisciplinaire en Didactique, Education et Formation, Université de Montpellier, 2 place Marcel Godechot, B.P. 4152, 
34092 Montpellier cedex 5, France
ABSTRACT
In the present paper, a case of leucism/piebaldism is reported in a striped panray Zanobatus schoenleinii 
(Müller & Henle, 1841) captured at a low depth off the coast of Senegal (eastern tropical Atlantic). This is the 
second case recorded to date for this species. The specimen was sub-adult male with developed but flexible 
claspers, which measured 495 mm total length and 279 mm disc width, and weighed 751 g. Comments on 
albinism in fishes are provided in this paper, especially those reported in batoid species.
Key words: morphology, colour, pigmentation, morphometric measurements, batoid species
ESEMPLARE LEUCISTICO DI ZANOBATUS SCHOENLEINII (CHONDRICHTHYES: 
ZANOBATIDAE) AL LARGO DELLA COSTA DEL SENEGAL 
(ATLANTICO TROPICALE ORIENTALE)
SINTESI
L’articolo riporta un caso di leucismo/piebaldismo in un esemplare di Zanobatus schoenleinii (Müller 
& Henle, 1841), catturato in acque poco profonde al largo della costa del Senegal (Atlantico tropicale 
orientale). Si tratta del secondo caso di questo tipo registrato fino ad oggi per tale specie. L’esemplare era un 
maschio sub-adulto, con pterigopodi sviluppati ma flessibili, di lunghezza totale pari a 495 mm, larghezza 
del disco di 279 mm e 751 g di peso. Gli autori discutono i casi di albinismo nei pesci, in particolare quelli 
riportati per le specie batoidi.
Parole chiave: morfologia, colore, pigmentazione, misure morfometriche, specie batoidi
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INTRODUCTION
The striped panray, Zanobatus schoenleiniii (Mül-
ler & Henle, 1841), is an endemic species known 
from the eastern tropical Atlantic, where it only oc-
curs in the area between southern Morocco (Lloris 
& Rucabado 1998), Mauritania (Maurin & Bonnet, 
1970), Senegal (Diatta et al., 2013), Guinea-Bissau 
(Sanches, 1991), and the Gulf of Guinea (Blache et 
al., 1970).
Zanobatus schoenleinii is both commonly and 
abundantly captured in handicraft fishery through-
out the coast of Senegal (Cadenat,1951; Séret 
& Opic, 1990; Capapé et al., 1995). The species 
inhabits shallow coastal waters not exceeding 50 
m of depth (Capapé et al., 1995). In the wake of a 
Fig. 1: Map of the Senegalese coast indicating the capture site of the leucistic 
specimen of Zanobatus schoenleinii (black star).
Sl. 1: Zemljevid senegalske obale z označeno lokaliteto, kjer je bil ujet belični 
primerek vrste Zanobatus schoenleinii (črna zvezdica).
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collaboration with experienced fishermen, several 
Z. schoenleinii were collected in shallow coastal 
waters surrounding the touristic area of Dakar. 
All collected specimens were delivered to the 
laboratory for thorough examination, including the 
abnormal specimens described and commented in 
the present paper.
MATERIAL AND METHODS
A total of 105 specimens were captured on 25 
May 2019 using trammel nets at a depth between 5 
and 10 m on soft bottom, off Ouakam, a 
handicraft fishery site located 5 km north 
Dakar, in Cape Verde Peninsula, Senegal, 
at 14° 43’ 26’’ N and 17° 29’ 21’’ W (Fig. 
1). Of these specimens, 104 were normal 
and one specimen abnormal, displaying 
non-pigmented areas on the dorsal sur-
face.
All specimens were measured to the 
nearest millimetre and weighed to the 
nearest gram. The normal specimens 
ranged between 253 mm and 580 mm 
in total length (TL), 154 and 340 mm in 
disc width (DW), and weighed between 
104 and 1433 g in total body weight 
(TBW). However, a sub-sample includ-
ing 51 normal specimens and the single 
abnormal specimen was used in order to 
obtain a more visible view, allowing to 
clearly distinguish this abnormal speci-
men from the normal specimens. The 
subgroup ranged between 250 and 300 
mm DW and weighed between 561 and 
1346 g TBW.
Morphometric measurements recorded 
on one of the normal specimens and the 
abnormal specimens are presented in Ta-
ble 1, following Diatta et al. (2013). Both 
specimens were fixed in 10% buffered for-
maldehyde, preserved in 75 % ethanol and 
deposited in the Ichthyological Collection 
of the Institut Supérieur d’Aquaculture et 
de Pêche of Bizerte (Tunisia), receiving 
catalogue numbers, ISPAB-Zan-sch-01 
for the normal specimen and ISPAB-Zan-
sch-02 for the abnormal specimen.
The relation between DW and TBW 
was used as a complement following Fro-
ese et al. (2011), including all specimens, 
normal and abnormal, to show if this 
latter would have been able to develop 
in the wild like normal specimens. This 
relation, TBW = aDWb, was converted 
into its linear regression, expressed in 
decimal logarithmic coordinates, and 
correlations were assessed by least-squares regres-
sion as: log TBW = log a + b logDW. Significance 
of constant b differences was assessed according to 
the hypothesis of isometric growth if b = 3, positive 
allometry if b > 3, negative isometry if b < 3 (Pauly, 
1983). These two latter tests were performed by us-
ing logistic model STAT VIEW 5.0.
RESULTS AND DISCUSSION
All normal specimens were identified as Zanoba-
tus schoenleinii following the combination of main 
Fig. 2: Normal specimen of Zanobatus schoenleinii (Ref. 
ISPAB- Zan-sch-01), from the coast of Senegal. Dorsal 
surface, scale bar = 100 mm.
Sl. 2: Normalni primerek vrste Zanobatus schoenleinii 
(Ref. ISPAB- Zan-sch-01) iz senegalske obale. Hrbtna 
stran, merilo = 100 mm. 
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morphological characters: disc sub-circular, wider 
than long; snout blunt, angle nearly 120° in front; 
nostrils narrow, anterior valves connected across 
the internarial space; mouth straight; teeth small; 
spiracles large without folds; dorsal and caudal fins 
small and rounded; covered by a rigid skin, unlike 
and minute scales, a medial row of thorns in disk 
and tail, and three rows arranged in an arc of circle 
on each shoulder; back brown with dark cross bands 
with white spots in between near the pectoral edges 
(Tab. 1; Fig. 2). Such description is in total agree-
ment with Garman (1913), Cadenat (1951), Blache 
et al. (1970), and Séret & Opic (1990). 
The abnormal specimen was a sub-adult male of 
Zanobatus schoenleinii, with developed but flexible 
claspers, measuring 495 mm TL, 279 mm DW and 
751 g TBW (Tab. 1; Fig. 3). The central part of the 
disc was brown with dark spots externally larger and 
abundant on the central part of the disc, conversely, 
dark cross bands were totally lacking. An area sur-
rounding eyes and spiracles was clear and whitish. 
The edges of both pectorals were largely clear, both 
dorsal fins and caudal fin whitish, belly entirely 
beige. The eye colour was black, which confirmed 
that the specimen was simultaneously leucistic and 
piebald and not a true albino (sensu Quigley et al. 
(2019). It is the second case reported for Z. schoen-
leinii, a similar specimen was previously collected 
from the coast of Senegal (Diatta et al., 2013).
Quigley et al. (2019) noted that albinism is a disor-
der controlled by different genes in which the pigment 
melanin is absent or non-functional. Additionally, 
leucism is a partial lack of pigmentation of the skin 
controlled by a single recessive allele (Jones et al., 
2016). The term partial albinism or pseudo-albinism 
was previously used, but is now considered obsolete 
(Van Grouw, 2006). Lipej et al. (2011) showed that 
large albino specimens of marbled torpedo Torpedo 
marmorata Risso, 1810 could also be captured in the 
wild and that, consequently, total or partial albinism 
does not compromise life and development. Similar 
patterns were also reported for the striped panray 
(Diatta et al., 2013). The relationship log DW versus 
log TBW is log TBW = -6.97 + 4.07 * log DW; r = 0.94, 
n = 52. It appears a positive allometry but the leucistic 
piebald specimen which clearly displays a TBW lower 
than this of the other specimens (Fig. 4). Following 
the opinion of Quigley et al. (2019), such pattern 
suggests that this abnormal specimen did not develop 
like other normal specimens in the wild due to being 
Fig. 3: Leucistic piebald specimen of Zanobatus schoenleinii (Ref. ISPAB- Zan-sch-01) from the coast of Sene-
gal. A. Dorsal surface, scale bar = 80 mm. B. Ventral surface, scale bar = 100 mm.
Sl. 3: Belični piebaldistični primerek vrste Zanobatus schoenleinii (Ref. ISPAB- Zan-sch-01) iz senegalske obale. 
A. Hrbtna stran, merilo = 80 mm. B. Trebušna stran, merilo = 100 mm.
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Tab. 1: The morphometric measurements (in mm and as % DW) and total body weight recorded in the leucistic piebald 
specimen of Zanobatus schoenleinii (ISPAB-Zan-sch-02) and compared to a normal specimen (ISPAB-Zan-sch-01), both 
from the coast of Senegal.
Tab. 1: Morfometrične meritve (v mm in kot % DW) in celotna telesna masa pri beličnemu piebaldističnemu primerku 
vrste Zanobatus schoenleinii (ISPAB-Zan-sch-02) v primerjavi z normalnim primerkom (ISPAB-Zan-sch-01). Oba sta 
bila ujeta ob senegalski obali. 
References ISPAB-Zan-sch-01 ISPAB-Zan-sch-02
Measurements MM % DW MM % DW
Total length 559 194.8 495 177.4
Disc length 313 94.8 255 91.4
Disc width 330 100.0 279 100.0
Disc depth 44 13.3 34 12.2
Eyeball length 17 5.2 18 6.5
Pre-orbital length 70 21.2 59 21.2
Inter-orbital length 26 7.9 28 10.0
Spiracle diameter 23 6.7 19 6.8
Interspiracular width 33 10.0 30 10.8
Space between eye and spiracle 13 3.9 11 3.9
Pre-oral length 72 21.2 60 21.5
Mouth width 43 13.0 43 15,4
First gill-slit 8 2.5 9 3.2
Fifth gill-slit 7 2.4 7 2.5
Width between first gill-slit 82 24.8 69 24.7
Width between fifth gill-slit 51 15.5 43 15.4
Snout tip to eye 81 24.3 68 24.4
Snout tip to mouth 81 24.3 68 24.4
Snout tip to first gill-slit 106 32.1 102 36.6
Snout tip to fifth gill-slit 150 45.5 132 47.3
Snout tip to vent 270 81.8 225 80.7
Pectoral fin anterior margin 205 71.4 185 66.3
Pectoral fin posterior margin 184 62.1 143 51.3
Pelvic fin anterior margin 50 15.2 48 17.2
Pelvic fin posterior margin 77 23.3 55 19.7
Second dorsal inneredge 10 3.0 11 3.9
Interdorsal distance 30 9.1 32 11.5
Second dorsal to caudal birth 28 8.6 35 12.5
Total body weight 1507 751
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maladapted. But it could also explain 
why of the 633 batoid species known 
to date worldwide, only 22 cases of 
albinism, leucism and piebaldsim had 
been reported (Quigley et al., 2018), 
23 including the present specimen.
Talent (1973) noted that lack of 
pigmentation could be considered 
as disadvantage for sharks and rays, 
calling the attention of possible 
predators to their presence in the 
wild. Generally, abnormal specimens 
are considered of lower value than 
normal specimens among fishermen 
and are sometimes discarded at sea; 
this could also explain their scarcity 
in fish landings. Unfavourable envi-
ronmental conditions, such as large 
exposure to pollutants, could also 
play a role in the lack of pigmenta-
tion, especially in species living a 
benthic zones, such as Zanobatus 
schoenleinii. Such phenomenon was 
particularly observed in batoids, 
which generally inhabit sandy-muddy 
bottoms (Ribeiro-Prado et al., 2008; 
Diatta et al., 2013). The fact that albi-
nos, leucistic and piebald specimens 
are more sensitive to pollutants than 
normal specimens remains a valid 
hypothesis, which should, however, 
be validated by further studies. Since 
Diop et al. (2012) and Bonnin et al. (2016) report that 
the coast of Senegal, especially around the touristic 
area of Dakar, has been, for decades, increasingly 
exposed to pollutants in the wild and their impact 
on the local biodiversity cannot be totally ruled out, 
the presently studied case could be a good instance 
of that.
Fig. 4: Total body mass (TBM) versus disc width (DW) relationship 
expressed in logarithmic co-ordinates for normal and leucistic piebald 
specimens of Zanobatus schoenleinii collected from the coast of Senegal.
Sl. 4: Odnos med celotno telesno maso (TBM) in širino diska (DW), iz-
ražen v logaritmični skali pri normalnih in leucističnih piebaldističnih 
primerkih vrste Zanobatus schoenleinii, ujetih ob senegalski obali. 
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BELIČNI PRIMEREK VRSTE ZANOBATUS SCHOENLEINII (CHONDRICHTHYES: 
ZANOBATIDAE) IZ SENEGALSKE OBALE (VZHODNI TROPSKI ATLANTIK)
Christian CAPAPÉ
Laboratoire d’Ichtyologie, Université de Montpellier, case 104, 34095 Montpellier cedex 5, France
e-mail: capape@univ-montp2.fr
Youssouph DIATTA & Almamy DIABY
Laboratoire de Biologie marine, Institut fondamental d’Afrique noire, (IFAN Ch. A. Diop), Université Cheikh Anta Diop de Dakar, 
BP 206, Dakar, Senegal
Sihem RAFRAFI-NOUIRA
Université de Carthage, Unité de Recherches Exploitation des Milieux aquatiques, Institut Supérieur de Pêche et d’Aquaculture de Bizerte, 
BP 15, 7080 Menzel Jemil, Tunisia
Christian REYNAUD
Laboratoire Interdisciplinaire en Didactique, Education et Formation, Université de Montpellier, 2 place Marcel Godechot, B.P. 4152, 
34092 Montpellier cedex 5, France
ABSTRACT
V pričujočem prispevku avtorji poročajo o primeru beličnosti/piebaldizma pri vrsti skata Zanobatus schoenleinii (Mül-
ler & Henle, 1841), ujetega v plitvini ob obali Senegala (tropski vzhodni Atlantik). Gre za drugi primer pojava te anomalije 
pri tej vrsti. Primerek je bil subadultni samec, ki je meril 495 mm v dolžino, 279 mm v premeru diska in tehtal 751 g, ter 
imel razvita, a še vedno prožna klasperja. Avtorji nadalje razpravljajo o primerih albinizma, še posebej tistih pri skatih.
Ključne besede: morfologija, barva, pigmentacija, morfometrične meritve, skati
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