Color pattern anomaly of the spotted pufferfish Arothron meleagris (Bloch & Schneider, 1801) in the Gulf of California, Mexico

Abstract

An anomalous specimen of the pufferfish Arothron meleagris was photographed at Cabo Pulmo reef, southwestern Gulf of California, Mexico (23.5°N-109.5°W). The specimen did not present white spots across the body (a diagnostic character of the species) but instead showed a reticulated pattern of white lines over a black-purple background. The coloration did not conform with that of any of the known species of Arothron, and we propose three explanations: a) this is a new species; b) we observed a hybrid of A. meleagris with another Indo Pacific species; or most probably, c) this is a very uncommon morphotype of A. meleagris never reported in the Americas.

Full text

Introduction
The spotted or guineafowl pufferfish Arothron meleagris
(Bloch & Schneider, 1801) is a common reef fish
distributed in the Indian Ocean and central Pacific
(Matsuura, 2016), and also along the eastern tropical
Pacific, from Mexico (27°N) to Ecuador (3°S), and in all
oceanic islands adjacent to the west coast of the Americas
(Bussing, 1995; Allen & Robertson, 1996). In the latter
region, the species is resident of coral and rocky reef areas,
at depths of 2 to 30 m, and it can grow to 30 cm in total
length (Bussing, 1995; de la Cruz-Agüero et al., 1997;
Reçu le 31 mai 2016 ; accepté après révision le 17 novembre 2016.
Received 31 May 2016; accepted in revised form 17 November 2016.
Cah. Biol. Mar. (2017) 58 : 207-211
Color pattern anomaly of the spotted pufferfish
Arothron meleagris (Bloch & Schneider, 1801)
in the Gulf of California, Mexico
Héctor REYES-BONILLA1and Arturo HERNÁNDEZ-VELASCO2
(1) Universidad Autónoma de Baja California Sur. Departamento Académico de Ciencias Marinas y Costeras.
Carretera al sur km 5.5., Col. El Mezquitito. CP 23080. La Paz, B.C.S., México
Email: hreyes@uabcs.mx
(2) Comunidad y Biodiversidad, A.C. Calle Isla del Peruano # 215 Col. Lomas de Miramar,
CP 85448, Guaymas, Sonora, México
Abstract: An anomalous specimen of the pufferfish Arothron meleagris was photographed at Cabo Pulmo reef,
southwestern Gulf of California, Mexico (23.5°N-109.5°W). The specimen did not present white spots across the body (a
diagnostic character of the species) but instead showed a reticulated pattern of white lines over a black-purple background.
The coloration did not conform with that of any of the known species of Arothron, and we propose three explanations: a)
this is a new species; b) we observed a hybrid of A. meleagris with another Indo Pacific species; or most probably, c) this
is a very uncommon morphotype of A. meleagris never reported in the Americas.
Résumé: Anomalie de couleur du poisson-globe tacheté Arothron meleagris (Bloch & Schneider, 1801) dans le Golfe de
Californie, Mexique. Un spécimen anormal du poisson-globe Arothron meleagris a été photographié au récif de Cabo
Pulmo, sud-ouest du Golfe de Californie, au Mexique (23,5°N-109,5°W). Le spécimen ne présentait pas de taches blanches
sur le corps (un caractère diagnostique de l’espèce) mais à la place un patron réticulé de lignes blanches sur un fond noir-
violet. La coloration n’est conforme à aucune autre espèce connue d’Arothron, et nous proposons trois explications : a) ceci
est une nouvelle espèce ; b) on a observé un hybride de A. meleagris avec une autre espèce de l’Indopacifique; ou plus
probablement, c) ceci est une forme très rare de A. meleagris jamais rapporté dans les Amériques.
Keywords: Cabo Pulmo reef lTetraodontidae lMorphological variability
DOI: 10.21411/CBM.A.3CAB24F

208 COLOR ANOMALY OF AROTHRON MELEAGRIS
Humann & DeLoach, 2003 & 2004). The species feeds on
algal turf, sponges, tunicates, mollusks and sea urchins, but
especially on reef corals of the genus Pocillopora
(Guzmán, 1988; Guzmán & Robertson, 1989; Guzmán &
López, 1991; Moreno et al., 2009). This fish is also
acknowledged for the high concentration of tetrodontoxin
in the skin, gonads and liver, which may work as a deterrent
to predators (Thomson et al., 2000).
One interesting feature of A. meleagris is the presence of
several color morphs that may work as aposematic
coloration against enemies. In one extreme, the pufferfish
can typically occur in the form of a black to deep purple
body covered by numerous small white spots (“spotted
phase”; Humann & DeLoach, 2004) and with the tail and
dorsal fin bordered in white, but there is also a second form
in which the body have a bright yellow coloration (“golden
pufferfish”); in this state, the belly is whitish, and the fins
(especially in the tail) have a gray or light purple lining at
the end (Thomson et al., 2000). In addition there are many
intermediate forms, presenting parts of the body black with
spots, and parts in yellow (Su & Tyler, 1986; Humann &
DeLoach, 2004). Also it is noticeable that in Indo Pacific
reefs, the species shows small white dots against a
completely black body, while in the eastern Pacific, the
spots are much larger (compare images in Su & Tyler, 1986,
Thomson et al., 2000 and in Matsuura, 2016). In short, the
color that this species can present show significant
variation depending on the geographic location where the
populations live.
The objective of this paper is to report and provide
photographic evidence of a very unusual specimen of A.
meleagris found at Cabo Pulmo reef, a marine park located
in the Gulf of California, Mexico, which has gained
notoriety because of the excellent state of the local marine
fish assemblages (Aburto-Oropeza et al., 2011). The color
pattern of the organism did not conform with that of any
other species of Arothron in the world, and represents the
first report of that kind of pigmentation for A. meleagris in
the eastern Pacific Ocean.
Methods
In September 2015, during a visit to Cabo Pulmo reef
(23.5°N-109.5°W), in the southwestern Gulf of California,
one of the authors of this note (AHV) noticed the presence
of very singular specimen of Arothron sp. at a depth of -20
m, and in a site locally known as “El Bajo”. Because of the
anomalous coloration, three photographs of the individual
were taken using a Canon PowerShot camera model SD990
IS, ISO 200, with no flash. Unfortunately, as the area is part
of a National Park the collection of the animal was not
allowed, a feat which would have been very useful to
confirm its identity. In absence of other evidence, the
images were compared with those of A. meleagris taken in
the field along the eastern Pacific by many divers and
researchers, with photos included in field guides and other
taxonomic references related to the eastern Pacific region
(e.g. Allen & Robertson, 1994), and also with the diagnoses
and dichotomic keys of Arothron spp. presented by Su &
Tyler (1986) and Matsuura (2016).
Results
The color pattern of the unusual fish (Fig. 1) was quite
different from the typical one of A. meleagris in the east
Pacific (Fig. 2). The organism that was spotted at Pulmo
reef had a reticulate pattern of white lines over a black
body, instead of the traditional white dots (small or large),
which were only observed around the mouth and in the
cheek. Also, the animal has a round black line around the
eye, and the belly was black and also presented the white
reticula. The dorsal and anal fin were yellow with black
stripes, and they had a conspicuous white line in the
posterior section.
It is important to notice that in over 40 years of
combined diving experience of the authors in reefs of the
Pacific, which includes immersions conducted from
northern Mexico to Ecuador, and in Japan and Indonesia,
we have never seen another example of A. meleagris
presenting this color configuration.
Discussion
Taking in consideration the key and diagnoses of Arothron
species presented by Su & Tyler (1986) and Matsuura
(2016), and of A. meleagris in the eastern Pacific by Allen
& Robertson (1996), Bussing (1995) and Garrison (2005),
we confirmed that the coloration pattern of the specimen
seen at Pulmo reef did not correspond to that of any other
spotted pufferfish ever reported in the Americas. The
differences included the fact that the eye were surrounded
by a black line, and that there were no multiple white spots
on the body; instead, the white lines across the entire body
and the reticulate pattern were perfectly appreciable.
Furthermore, no illustration or photography of A. meleagris
that we found in the literature and taken either in locations
of the west coast of the Americas or in the central or
western Pacific, showed any similar design.
Notwithstanding, Su & Tyler (1986) indicated that in some
individuals of this species the spots elongates ventrally
forming a reticulate pattern; however, the geographic origin
of these specimens was not referred, and no illustrations are
provided in the paper.
On the other hand, the fish seen at Pulmo reef resembled
other species of the genus; for example, the lines on the

H. REYES-BONILLA, A. HERNÁNDEZ-VELASCO 209
Figure 1. Arothron meleagris. Anomalous specimen observed at Cabo Pulmo reef. Notice the conspicuous reticulated white lines that
cover the body, and the virtual lack of white dots (diagnostic character of the black-purple phase of the species), except in the face.

210 COLOR ANOMALY OF AROTHRON MELEAGRIS
Figure 2. Arothron meleagris. A comparison of the unusual specimen seen at Pulmo reef (above), with another from the same location
but showing the typical coloration (below).

body were alike those presented by Arothron multilineatus
Matsuura, 2016; however, this fish has a green-brown
coloration (not black or purple) in the body and tails, a
white ventral section (instead of black), and has no black
ring surrounding the eye. Moreover, the geographic range
of A. multilineatus comprises from Mozambique to Japan
and the Philippines, on the other side of the Pacific Ocean.
Another possibility is that the fish in Figure 1 was a form
of Arothron reticularis Bloch & Schneider, 1801, a species
of pufferfish distributed from India to Australia (Matsuura,
2016), because both present conspicuous white lines along
the body. Nevertheless, the body of the latter species is
greenish, shows white dots on the tail fin (absent in the
organism pictured in Figure 1), and the belly is completely
white (not black as the fish from Cabo Pulmo). Finally,
Arothron carduus (Cantor, 1849) also has lines all along the
body, but the color of the body scales is white, not black.
From all these comparisons, we judge that the organism
photographed at the Gulf of California did not correspond
to any species of Arothron so far known, or instead it is a
very unusual form of A. meleagris, which is the only
representative of its genus in the east Pacific.
The first possibility to explain our finding is that the fish
in figure 1 belongs to a new species unknown to science.
Although that might be probable, the lack of a collected
specimen precludes to present any argument other than
opening the possibility of the case. Rocha et al. (2014)
discuss the need of having voucher specimens to deposit in
scientific collections to better document biological
variability, even if the organism is found in a protected area.
Although we endorse that opinion, in this particular situation
the Mexican law is very explicit on the limitations of
collecting inside a national park, and we believe that in the
long term, this position is acceptable in order to maintain the
health of the local populations.
A second option was to consider that the organism
photographed in Baja California was a hybrid of melagris
and another species that have the reticulated pattern,
probably multilineatus or reticularis. However, the
distribution area of these two species is very far away from
the location of Cabo Pulmo reef (more than 5,000 km to the
west), and thus the possibility is quite remote. After all
these considerations, and following the observations of Su
& Tyler (1986), we suggest that the unusual organism seen
might actually be a very uncommon form of A. meleagris,
which has not been referred previously in the specialized
literature on reef fishes of the eastern Pacific.
Acknowledgements
Funding for the visit to Pulmo reef was provided by Cabo
Pulmo Dive Center. Pilar Hermosila collaborated in the
field work, and Israel Sánchez provided the image of
Arothron meleagris showing its typical coloration in the
eastern Pacific. We are grateful for the suggestions of two
anonymous reviewers, that improved the quality of the final
product.
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