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Two types of Berardius are recognised by local whalers in Hokkaido, Japan. The first is the ordinary Baird’s beaked whale, B. bairdii, whereas the other is much smaller and entirely black. Previous molecular phylogenetic analyses revealed that the black type is one recognisable taxonomic unit within the Berardius clade but is distinct from the two known Berardius species. To determine the characteristics of the black type, we summarised external morphology and skull osteometric data obtained from four individuals, which included three individuals from Hokkaido and one additional individual from the United States National Museum of Natural History collection. The whales differed from all of their congeners by having the following unique characters: a substantially smaller body size of physically mature individuals, proportionately shorter beak, and darker body colour. Thus, we conclude that the whales are a third Berardius species.
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SCIENTIFIC REPORTS | (2019) 9:12723 |
Description of a new species of
beaked whale (Berardius) found in
the North Pacic
Tadasu K. Yamada1, Shino Kitamura2,3, Syuiti Abe3, Yuko Tajima1, Ayaka Matsuda3,
James G. Mead4 & Takashi F. Matsuishi3,5
Two types of Berardius are recognised by local whalers in Hokkaido, Japan. The rst is the ordinary
Baird’s beaked whale, B. bairdii, whereas the other is much smaller and entirely black. Previous
molecular phylogenetic analyses revealed that the black type is one recognisable taxonomic unit
within the Berardius clade but is distinct from the two known Berardius species. To determine the
characteristics of the black type, we summarised external morphology and skull osteometric data
obtained from four individuals, which included three individuals from Hokkaido and one additional
individual from the United States National Museum of Natural History collection. The whales diered
from all of their congeners by having the following unique characters: a substantially smaller body
size of physically mature individuals, proportionately shorter beak, and darker body colour. Thus, we
conclude that the whales are a third Berardius species.
Beaked whales (Family Ziphiidae, Odontoceti, Cetacea) include the second largest number of species among
toothed whale families. eir preference for deep ocean waters, elusive habits, and long dive capacity1 make
beaked whales hard to see and inadequately understood. A total of 22 species are currently recognized in six
genera (Berardius, Hyperoodon, Indopacetus, Mesoplodon, Tasmacetus, and Ziphius)2. e genus Berardius has
two species, Baird’s beaked whale Berardius bairdii, found in the North Pacic and adjacent waters, and Arnoux’s
beaked whale B. arnuxii, found in the Southern Ocean3. Besides the two nominal species, however, whalers
observations o Hokkaido, northern Japan, have alluded to the occurrence of two groups of Berardius, one being
slate-gray form and the other, the black form, which are smaller in body size4,5. Today, slate-gray form is common
around Japan, which are traditionally considered as B. bairdii, but black form is rare, and no detailed morpholog-
ical examinations have been conducted so far. Recent molecular phylogenetic analyses strongly suggest the black
and the slate-gray forms in the North Pacic as genetically separate stocks of Berardius6,7, awaiting further work
with sucient morphological data to verify the dierences between the two types of Berardius.
Here, we examined black type beaked whale external morphology and skull osteometric data obtained from
four specimens including three from Hokkaido and one from the United States National Museum of Natural
History (USNM) collection, to highlight the morphological characteristics of the black form aer compari-
son with those of their congeners, B. bairdii and B. arnuxii. e observed unique external characters and skull
osteomorphology, coupled with updated molecular phylogeny of Berardius, distinguish the black form as a third
Berardius species previously unknown in cetacean taxonomy.
Genus Berardius
Before discussing the above-mentioned subject, it would be useful to summarise what is known about the genus
Berardius. Berardius was established by Duvernoy in 18518, who described B. arnuxii based on a specimen col-
lected in New Zealand. e skull and mandibles of this individual are preserved in le Museum Nationalle d’His-
toire Naturelle (MNHN) in Paris. Stejneger9 described a similar species of this genus, B. bairdii Stejneger (USNM
20992), as a northern counterpart in 1883; this description was published just a few months earlier than Malm’s10
description of B. vegae, which was later dened as a junior synonym of B. bairdii11. Both specimens were collected
1Department of Zoology, National Museum of Nature and Science, Tsukuba, Ibaraki, Japan. 2Sanriku Fisheries
Research Centre, Iwate University, Kamaishi, Iwate, Japan. 3Faculty of Fisheries Sciences, Hokkaido University,
Hakodate, Hokkaido, Japan. 4Division of Mammals, Smithsonian Institution, Washington, D.C., USA. 5Global
Institution for Collaborative Research and Education, Hokkaido University, Hakodate, Hokkaido, Japan.
Correspondence and requests for materials should be addressed to T.F.M. (email: catm@
Received: 30 November 2018
Accepted: 4 July 2019
Published: xx xx xxxx
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from Bering Island. e B. bairdii holotype includes a skull and mandibles, and the B. vegae holotype consisted of
broken skull pieces. B. arnuxii and B. bairdii could be good examples of antitropical distribution12.
As summarised by Kasuya5,13, there have been extensive debates on the identities of these two species, because
they are very similar except for body size and distribution. B. arnuxii is slightly smaller than B. bairdii. True11
pointed out several characters that are distinct between these two species. However, as the number of specimens
increased, most of the characters lost systematic signicance, and their validity was disputed14,15. Dalebout et al.16
put an end to this discussion and showed that the two species are genetically distinct and independent. However,
morphological discrimination of these two species is not currently well established and we have to rely on molec-
ular results or distribution to discriminate these two species. Ross17 noted that more thorough morphological
investigations are needed to distinguish B. bairdii and B. arnuxii.
Berardius skulls are the least asymmetrical and sexually dimorphic among genera of the family Ziphiidae;
only the body length of females is slightly larger than that of males. e beak is straight and long. Unlike most
other ziphiids, they have two pairs of teeth in the lower jaw. e blowhole slit is unique, with a posteriorly opened
arch that is unlike those of all other odontocete groups (e.g. Kasuya18). Although the nasals are large, they do not
overhang the superior nares.
History of Berardius in Japan
In 1910, True11 summarised the ziphiid specimens that were preserved and stated “Berardius is the rarest genus,
only about fourteen specimens having been collected thus far. Also in 1910, Andrews visited the Imperial Museum
at Tokyo, which is now called the National Museum of Nature and Science (NMNS), to nd a B. bairdii skeleton19;
this occurred when existence of Berardius in Japan was known to science and, on this historical occasion, B. bairdii
was conrmed to correspond to “tsuchi-kujira”20 of Japan. When considering the recognition of B. bairdii in Japan,
however, the Japanese name tsuchi-kujira had been used since the early 18th century, and whaling activities have
been aimed at this species since then2124. Proper comparison and recognition of this species using the Western (or
Linnean) systematic scheme took some time aer the introduction of modern science from the West, which began
in 1868 aer the Meiji Restoration. Researchers such as Okada25 incorrectly identied tsuchi-kujira as Hyperoodon
rostratus, and this notion was generally accepted in most publications. In 1910, Andrews examined the specimens of
tsuchi-kujira (then recognised as H. rostratus) that were exhibited in the Imperial Museum in Tokyo, and identied
them as B. bairdii19. He surveyed the locality of this B. bairdii specimen and collected a whole skeleton of this species
in Chiba. is event was reported by Nagasawa20 to the Zoological Society of Japan and conrmed the existence of
B. bairdii in Japanese waters.
e following description was prepared by Tadasu K. Yamada, Shino Kitamura and Takashi F. Matsuishi.
Order CETARTIODACTYLA Montgelard, Catzeis and Douzery, 199726.
Infraorder CETACEA Brisson, 176227
Parvorder ODONTOCETI Flower, 186428
Family ZIPHIIDAE Gray, 186529
Genus BERARDIUS Duvernoy, 18518
Berardius minimus s p. nov.
(New Japanese name: Kurotsuchikujira)
Etymology. e specic name reects the smallest body size of physically mature individuals of this species
compared with the other Berardius species. Historically, whalers in Hokkaido recognised this species as dierent
from B. bairdii and called them “kuro-tsuchi”, which means black Baird’s beaked whale; however, the colour dif-
ference mainly depends on the scar density and is not biologically fundamental (Figs1 and 2). We therefore chose
the most basic dierence, the signicantly small body size, which is smallest among the congeners, to be reected
in the scientic name.
Holotype. Adult male (NSMT-M35131) skull, mandible, and most of post of postcranial skeleton at National
Museum of Nature and Science (NMNS). In addition, tissue samples are also preserved at the NMNS. is spec-
imen, a fairly well decomposed stranded carcass was found on 4 June 2008 (Fig.3A–C). Upon receiving notice,
SNH took action, and Prof. Mari Kobayashi of Tokyo University of Agriculture and her students examined the
carcass on-site. e carcass was then buried at a nearby. e whole skeleton was excavated and recovered on 26
and 27 August 2009 by one of us (SNH), Tokyo University of Agriculture, Institute of Cetacean Research, and
Type Locality. Tokoro Town (44°0714.5N, 144°0629.6E), Kitami City, Hokkaido, Japan, southern Okhotsk
Sea, North Pacic.
Nomenclatural statement. A Life Science Identier (LSID) was obtained for the new species (B. mini-
mus):, and for this publication: urn:l-
Diagnosis. Berardius minimus diers from all of its congeners by having the following unique characters:
remarkably smaller body size of physically mature individuals, proportionately shorter beak, darker body colour
subsequent noticeable cookie-cutter shark bites.
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External characters. External appearance is mostly known from a male individual found stranded on 10
November 2012 in Sarufutsu, Hokkaido (Fig.4). Most of the external characters of B. minimus are typical of
medium- to large-sized ziphiids, with several discriminating characters, such as the narrow, straight, and longer
beak; reverse V-shaped throat grooves; relatively smaller ippers (ipper length is 11.4% of body length on aver-
age; range, 7.7–13.4%); small dorsal n (dorsal n height is 3.7% of body length on average; range, 3.4–3.9%)
located 70% of body length (on average; range, 66.7–71.8%); and tail ukes that lack the median notch. However,
the posteriorly opened crescent-shaped blowhole slit indicates Berardius anity. Additionally, B. minimus has a
substantially smaller body size (maximum body length of 6.9 m in physically mature individuals, so far), more
spindle-shaped body, and relatively shorter beak, which is approximately 4% of the body length and is not con-
sistent with the morphology of either of the known Berardius species.
Body colour is almost black with a pale white portion on the rostrum; this is in contrast to B. bairdii, which
is described as “slatish4 or “slate grey”6,7 or B. arnuxii, which is described as black30 or light grey31. e greyish
tone of the B. bairdii body is mainly attributed to the dense healed scars that are probably caused by intraspecic
conicts and/or behaviour. At least in adult and subadult individuals of B. minimus, cookie-cutter shark bites
are fairly conspicuous, but not to the extent as usually seen in some other species such as Ziphius cavirostris,
Mesoplodon densirostris, and/or Balaenoptera borealis. e darker body colour with almost no scars produces a
sharp contrast with the healed cookie-cutter shark bites, which are white and very conspicuous against the black
body of B. minimus.
e beak is much shorter than in the other two Berardius species. In B. bairdii, the head proportions are
extremely small, and are much smaller than that of B. minimus. Body colour is almost uniformly dark brown with
a whiter portion at the tip of rostrum. No white patch on the belly was conrmed in B. minimus. An illustration of
an adult male of B. minimus is shown as Fig.5. At present, we do not know what adult females look like.
Figure 1. Unidentied beaked whale incidentally caught in Shibetsu, Hokkaido (photo taken by Minako
Kurasawa on 20 July 2004, courtesy of Hal Sato).
Figure 2. Unidentied beaked whales sighted in Nemuro strait. Note the short beak, dark body colour, and
sparse linear scars (photo taken by Hal Sato on 21 May 2009).
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Figure 3. Severely decomposed beaked whale stranded in Kitami, Hokkaido on 4 June 2008. (A) e relatively
shorter beak indicates it is not B. bairdii (photo taken by Mari Kobayashi), (B) although the blow hole shape
indicates it belongs to Berardius (photo taken by Mari Kobayashi). (C) e general body shape is that of typical
ziphiid species. When compared with adult B. bairdii, this specimen is more spindle-shaped.
Figure 4. Fresh carcass of Berardius minimus (male, 662 cm) found stranded on 10 November 2012 in
Sarufutsu Hokkaido. (A) Ventral view of the carcass. Note the whole body is almost black exceptfor the faintly
white beak. (B) e relatively short beak of the same individual (photos taken by Yasushi Shimizu).
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External measurements. As mentioned above, the distinctly small body length of physically mature indi-
viduals and proportionately shorter beak are the most reliable characters which indicate that the population in
question represents a species that was previously not known to science.
Regarding body length, a strong signicant dierence was found between the body length of male B. bairdii
from the Okhotsk Sea (n = 34)32 and mature male B. minimus (n = 4, Table1) (Welch’s t-test, t = 18.5, P < 0.001).
To conrm relative rostrum-to-body length, Welch’s t-test was also conducted. For B. minimus, four samples
in Table1 were analysed. For B. bairdii, the mean and standard deviations for male B. bairdii in the Okhotsk Sea
(n = 29) that appeared in Table2 of Kishiro32 were used. Rostrum length was standardised by body length, and
was 3.62 ± 0.39 SD% (n = 4) for B. minimus and 5.81 ± 0.80 SD% (n = 29) for B. bairdii. Welchs t-test showed
strong signicant dierence (P = 2.3 × 105). Female B. bairdii relative length was 6.27, which is longer than that
of males. Note this female was not physically mature. e dierence between B. minimus and B. bairdii was obvi-
ously larger if the sex-pooled data were used. A strong signicant dierence was also found between B. minimus
and B. bairdii in the Pacic Ocean and Sea of Japan (P < 0.001). us, the relative rostrum length of B. minimus
was signicantly shorter than that of B. bairdii. However, we note that the sample size for both B. minimus and
B. arnuxii are extremely small, in contrast to B. bairdii.
Skull morphology. e skull morphology resembles the skulls of both existing Berardius species, but B. minimus
has a distinctly shorter rostrum if contrasted to the condylobasal length, and smaller bulla and periotic bone. In general,
the sutures are more tightly closed in B. minimus than those in the other Berardius species. In the hyoid bone, thylohyal
and basihyal are not fused at all (Fig.6).
Superior aspect. e following characters are readily recognisable as species-specic. e relative beak length in
B. minimus is clearly smallest among the three Berardius species. e B. minimus skull has much tighter sutures
compared with those in both B. arnuxii and B. bairdii. e proportional distance of the anterior end of the max-
illae from the tip of the rostrum (i.e. premaxillae) relative to condylobasal length of the skull is much smaller in
B. minimus (6.93% in NSMT35131) than the two previously known Berardius species (which have a distance of
approximately 10%). e inclination of the occipital bone is stronger in B. minimus, and the occipital plane is
much wider compared with the other two species. e antorbital notch is proportionately narrower in B. mini-
mus than in B. bairdii but similar to that in B. arnuxii. e B. minimus rostrum has simple tapering contour lines
toward the tip, whereas both contour lines of the rostrum are parallel in B. bairdii and B. arnuxii. e lateral
border of the orbit, which consists of the maxilla and frontal bones, is almost parallel to the sagittal plane in B.
minimus, but is oblique in other two species.
Lateral aspect. e relative rostrum length is obviously shorter in B. minimus, and the B. minimus rostrum also
looks much shorter than those of the other two species in side view. e skull height relative to condylobasal
length is much larger (0.41–0.44) in B. minimus than those in B. bairdii (0.35–0.40) and B. arnuxii (0.40–0.41).
ere is stronger inclination of the higher portion of the occipital plane in B. minimus, and the convexity of the
occipital plane is stronger in B. minimus. e temporal fossa is the shallowest in B. minimus and the medial wall
of the fossa is convex, but is concave in B. bairdii and B. arnuxii.
Posterior aspect. e structure above the temporal fossa is proportionately much larger and higher in B. mini-
mus than those in B. bairdii and B. arnuxii, which gives the impression that the B. minimus skull is rather triangu-
lar in the posterior view, whereas those of the other two species are pentagonal.
Anterior aspect. In the frontal view, lateral expansion of the premaxillae at the posterior is prominent, and the
posterior margins of both maxillae are clearly visible in B. minimus.
Figure 5. Illustrations of (A) Berardius minimus, and (B) B. bairdii. e black bars show 1 m. In general
appearance, B. minimus resembles a small B. bairdii with a proportionately shorter beak and more spindle-
shaped body (drawn by Yoshimi Watanabe, National Museum of Nature and Science).
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In B. minimus, the height of skull relative to the width is much higher than those of the other Berardius species.
e prominential notch and related structure are much higher, more distinct and more rugged in B. bairdii and
B. arnuxii.
Teeth. As in the other two Berardius species, B. minimus has two pairs of teeth only at the tip of the lower jaw.
e anterior tooth is much larger than the posterior tooth. Teeth dimensions of the holotype are shown in Table3
(57-1 and 2, 58-1 and 2). In the holotype specimen of B. minimus the pulp cavities are almost closed in all teeth
other than the right 2nd tooth, where the pulp cavity is open.
No. Specimen ID SNH ID Sex Body
Length cm Found date Locality L atitude
Longitude stranding Specimen Growth
Stage Analyses
1 NSMT M35131 08019 M 660 2008.06.04 Japan Hokkaido Kitami 44°0714.50N
144°0629.60E Stranding complete
skeleton Physically
mature *,†,‡
2 NSMT M36219 09009 F U 2009.05.11 Japan Hokkaido Rausu 44°0049.80N
145°1472.00E Dring severed
head Neonate?
3 NSMT M35206 09016 F 621 2009.06.17 Japan Hokkaido Utoro 44°0218.40N
144°5601.30E Stranding complete
skeleton Physically
immature †,‡
4 NSMT M42000 12044 M 630 2012.08.23 Japan Hokkaido Rausu 44°0922.07N
145°1733.03E Driing almost
mature *,†,‡
5 NSMT M42012 12054 M 662 2012.11.10 Japan Hokkaido Sarufutsu 45°2021.30N
142°1009.27E Stranding complete
skeleton Physically
mature *,†,‡
6 NSMT M42610 14016 M 690 2014.06.14 Japan Hokkaido Rausu 44°0556.94N
145°1838.16E Driing complete
skeleton Physically
mature *,‡
Table 1. List of Berardius minimus specimens that were stranded or driing and collected in Hokkaido.
*Indicates individuals used for body length analysis, for external measurement comparison, and for molecular
phylogenetic analysis.
Berardius mini mus n = 4 Berardius bairdii n = 10 Berardiu s arnuxii n = 7
mean s.d. min max mean s.d. min max mean s.d. min max
Measurement items
SI1 970 42.9 935 1,042 1,346 76.5 1,158 1,403 1,314 100.3 1,161 1,410
SI2 888 36.1 861 949 1,211 63.8 1,089 1,287 1,148 91.3 1,023 1,253
SI3 Le 656 47.5 617 737 953 59.7 805 1,006 925 73.4 794 1,023
SI4 Le 754 44.7 716 827 1,085 47.7 973 1,148 1,038 86.6 891 1,137
SI5 770 39.7 732 835 1,097 61.8 967 1,183 1,076 96.3 915 1,190
SI6 Le 915 30.9 890 968 1,215 78.1 1,027 1,298 1,194 98.8 1,053 1,301
SI7 609 37.2 577 670 864 54.6 725 921 835 71.9 696 918
SI11 280 10.4 268 292 377 33.4 314 434 362 26.5 325 394
SI12 411 10.7 394 422 521 33.2 456 573 522 46.2 442 572
SI13 173 13.3 151 186 227 14.6 207 258 211 23.2 179 248
SI16 60 7.4 49 69 78 8.8 60 86 76 3.5 72 82
SI18 101 9.4 86 111 118 18.2 103 163 121 11.8 106 140
SI20 91 6.6 84 102 112 7 103 125 132 11.2 118 155
SI23 75 2.9 71 79 96 9.1 74 111 93 7.4 84 108
SI25 132 31 79 157 225 9.9 210 241 214 17.1 195 249
SI28 135 14.3 118 157 155 9 134 169 166 14.1 141 183
SI29 61 4.3 55 67 80 5.7 70 88 90 8.6 78 104
SI31 125 8 112 132 194 14 163 216 176 14.5 160 199
SI32 65 1.5 63 67 112 8.9 94 126 99 10 86 115
SI33 64 3.7 58 67 97 5.9 89 105 90 10.3 77 104
SI36 Le 145 8.5 133 154 174 19.6 151 208 219 22.3 179 258
SI37 Le 84 14 68 106 108 13.1 83 123 110 13.9 86 128
SI39 548 46.8 497 624 794 54 665 869 794 74.9 682 908
SI40 Le 521 31.3 485 565 858 226.2 647 1,305 750 62.2 656 818
SI41 491 30.3 461 534 737 48.4 623 787 717 63.4 618 781
SI42 723 44.8 680 796 1,018 58.3 858 1,078 995 78.9 858 1,070
SI45 115 2.9 110 117 166 12.6 152 197 163 8 152 175
Table 2. Mean, standard deviation, and range of each measurement by species.
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Post cranial skeleton. e vertebral column has proportionately high spinous processes, which is observed in
most ziphiid species (Fig.7). e bone matrix is coarse and porous, and they oat on the processing water aer
internal so tissue was removed. In the holotype specimen, the vertebral formula is C. 7, . 10, L. 10, Ca. 19,
making the total count as 46. Among 7 cervical vertebrae, C1–C3 were fused. L4 and L5 are the tallest vertebrae.
Ca10 and 11 are so-called ball vertebrae. Ten chevrons were counted. Ribs are in 10 pairs, among which seven
pairs are dual-headed with both costovertebral and costotransversal articulations. e remaining three pairs have
Figure 6. Skull of the B. minimus holotype. (A) Dorsal, lateral, and ventral views of the skull. Note the relatively
short rostrum. e white bar indicates 10 cm. (B) Anterior and posterior views of the skull. e dorsal view
is more triangular, whereas the dorsal views in B. bairdii and B. arnuxii are more pentagonal. e white bar
indicates 10 cm. (C) Lingual (inner, upper) and buccal (outer, lower) sides of the le mandible. e white bar
indicates 10 cm. (D) Buccal (external) view of the anterior (le) and posterior (right) teeth of the lower jaw. e
white bar indicates 1 cm.
Table 3. Skulls used for craniometry analyses. Twenty-one specimens (10 Berardius bairdii, seven B. arnuxii,
and four B. minimus). Specimens are stored at National Museum of Nature and Science (NMNS), United States
National Museum of Natural History (USNMH), Natural history Museum of London (BMNH), le Museum
National d’Histoire Naturelle (MNHN), and Museo Acatushún (MA). Items with * were used for multivariate
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only one articulation facet which articulate with “transverse” processes of the caudal thoracic vertebrae. No ossi-
ed cervical ribs were found. e sternum is composed of ve segments.
Paired ossied pelvic bones have a lateral surface which is fairly smooth; however, in the medial surface,
approximately two-thirds of the total length is an elevated area where the corpus cavernosum penis attaches.
Viewed from the dorsal side, the pelvic bones show a very gentle s-shape. No rudimental femur or any additional
appendicular bone was collected.
Pectoral appendage. Regrettably, we could not secure all phalangeal bones of the le ipper. On the right side,
there are three carpal bones in the proximal row, possibly the Ossa radiale, centrale, and ulnare. In the distal row
are another three carpal bones. All ve digits have one each metacarpal; the phalangeal formula is 0-5-4-3-2.
Multi-measurement comparison. Table2 shows the mean, standard deviation, and range of each meas-
urement by species. PCA showed that the contribution of the rst principal component (PC1) was 73.9%, and the
cumulative contribution reached 90% for PC1-6. us, linear discriminant analysis was conducted using PC1-6.
Table4 shows the linear discriminant coecients obtained by linear discriminant analysis (LDA). e linear
discriminants coecients of each sample are plotted in Fig.8. e distribution of the linear discriminants variates
was very clearly separated by species.
Genetic considerations. Molecular phylogenetic relationships among three Berardius species were exam-
ined using nucleotide sequence variation of the mitochondrial (mt)DNA control region (CR). The 879-bp
complete CR sequence data from eight B. minimus specimens (Table5) (Acc. Nos AB572006-AB572008 from
Kitamura et al.6, Acc. Nos LC175771-LC175773 in this study, and Acc. Nos KT936580-KT936581 from Morin
et al.7) showed ve haplotypes with only 1–4 nucleotide dierences without gaps aer multiple alignment. Using
the CR sequences aligned with 430-bp B. arnuxii sequences (Acc. Nos AF036229 and AY579532 from Dalebout
et al.16) excluding gaps, the number of nucleotide dierences between B. minimus and its congeners was 18–22
for B. bairdii and 25–29 for B. arnuxii. us, the mtDNA nucleotide dierence between B. minimus and any of
its congeners was much greater than the dierence between B. bairdii and B. arnuxii, which is 12–16 nucleotides.
e observed CR nucleotide dierences supported the distinct position of B. minimus in the Berardius tree con-
structed from 430-bp sequences using the maximum likelihood method, where B. bairdii and B. arnuxii formed
a sister clade (Fig.9).
Known distribution. As is indicated by the map of localities where B. minimus was found (Fig.10), their
known distribution is very limited and occurs between 40°N and 60°N, and 140°E and 160°W.
Kasuya5,18 summarised Hokkaido whalers’ traditional knowledge. The whalers recognised two types of
tsuchi-kujira: the ordinary “tsuchi-kujira” (Berardius bairdii) and the darker and smaller “kuro-tsuchi” (black
Baird’s beaked whale) or “karasu” (crow). However, it is unclear whether “kuro-tsuchi” and “karasu” are used to
describe the same type of whales or each notion represents the dierent population.
In this study, we described a new species, B. minimus, which corresponds to “kuro-tsuchi”. If “karasu” exists
as a third type, it could be a species that is not yet recognised or a Mesoplodon species found in Hokkaido (either
M. stejnegeri or M. carlhubbsi). Recognition of these Mesoplodon species around Hokkaido is rather recent; the
PCA1 0.101 0.223
PCA2 0.774 0.348
PCA3 0.416 0.065
PCA4 0.101 0.223
PCA5 0.774 0.348
PCA6 0.416 0.065
Table 4. Linear discriminant coecients obtained by linear discriminant analysis (LDA).
Figure 7. Articulated skeleton of the B. minimus holotype specimen.
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SCIENTIFIC REPORTS | (2019) 9:12723 |
earliest M. stejnegeri specimen was collected in 198533, and the earliest M. carlhubbsi in 200434. ese Mesoplodon
species were not recognised as distinct species by whalers or the media until recently.
As was also pointed out by Kasuya18, Fig. 364 and 366 of Heptner35 hinted at the possibility of a
Hyperoodon-like whale in the northern Pacic. e animal in the photo was denitely not Berardius. is could
be a species of probably about 10-m long with a beak almost like that of Hyperoodon. We suspect this could be an
example of an extralimital occurrence of H. ampullatus. Considering the recent sightings of the gray whales in the
Mediterranean or in Namibia36,37, the possibility of vagrant individual navigate through the Northwest passage
during summer should be studied.
e species we described is rather readily recognisable by people with whale taxonomy experience based on
the external characters. e species has an obviously smaller body size, which is 6.3–6.9 m in physically mature
individuals, so far we conrmed (Morin et al.7 reported an adult male with 7.3 m body size). eir body size
Figure 8. Linear discriminant variates of each sample are plotted. e linear discriminants variates are clearly
separated by species. B: Berardius bairdii, A: B. arnuxii, M: B. minimus.
Code Haplot ype No. Acc. No . Reference
B. minimus
SNH08019 1 AB572006 Kitamura et al.6
SNH09009 2 AB572007 Kitamura et al.6
SNH09016 3 AB572008 Kitamura et al.6
SNH12044 1 LC175771 this study
SNH12054 3 LC175772 this study
SNH14016 3 LC175773 this study
4 KT936580 Morin et al.7
5 KT936581 Morin et al.7
B. bairdii
EW01000 1 AB571999 Kitamura et al.6
EW01005 2 AB572000 Kitamura et al.6
EW00997 3 AB572001 Kitamura et al.6
EW01015 4 AB572002 Kitamura et al.6
EW01007 5 AB572003 Kitamura et al.6
EW00999 6 AB572004 Kitamura et al.6
EW01004 7 AB572005 Kitamura et al.6
B. arnuxii
1 AF036229 Dalebout et al.16
2 AY579532 Dalebout et al.16
I. pacicus (outgroup)
NSMT M33006 1 AB572012 Kitamura et al.6
Table 5. Individuals and sequences used in this study. SNH: Stranding Network Hokkaido, Hokkaido, Japan;
EW: Ehime University es-Bank, Ehime, Japan; NSMT: National Museum of Nature and Science, Ibaraki, Japan.
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SCIENTIFIC REPORTS | (2019) 9:12723 |
ranges from 9.1–11.1 m in B. bairdii and 8.5–9.75 m in B. arnuxii38. ey have a relatively short beak that is
approximately 4% of the body length. ey have a dark body colour, which is almost uniformly black with notice-
able healed cookie-cutter shark bites forming white dots; this impressively contrasts with the much lighter col-
ouration of B. bairdii and likely result from healed scratches and scars that were probably caused by intra-specic
struggling and bottom-feeding behaviour.
Osteologically, the small body size of physically mature individuals is the main dening character of B. min-
imus. Condylobasal length of the skull is 935–1042 mm, in contrast to 1343–1524 mm in B. bairdii and 1174–
1420 mm in B. arnuxii9. Skull characters indicate signicant inuence of size dierence, such as tighter bone
sutures compared with those of other Berardius species. Skull elements of the brain case are relatively large and
conspicuous. e vertebral formula of the type specimen is C. 7, . 10, L. 10, Ca. 19 (totalling 46), whereas it is
C. 7, . 9–11, L. 12–14, Ca. 17–22 (47–52) in B. bairdii and C. 7, . 10–11, L. 12–13, Ca. 17–19 (47–49) in B.
arnuxii13. Rib count, which reects the thoracic vertebral count, is 10 in the B. minimus type specimen.
As was mentioned above, when comparing the skull sutures in similarly mature individuals of dierent spe-
cies of cetaceans, there is a general tendency that the larger the adult form is the less rigid skull composition is
observed. Cetacean facial skull consists loosely articulated bones, including the maxillae, premaxillae and fron-
tals, which are adhered to the mesorostral cartilage pillar on the vomer by connective tissue. It is a physically
signicant principle where cetaceans swing their rostrum in the water for foraging. It requires tremendous power
and the exibility of the skull structure must ease the stress given to the skull structure. In this context it is quite
reasonable that the skull of B. minimus is far more rigidly composed compared to those of the far larger species,
Figure 9. Maximum likelihood-based molecular phylogenetic relationships among the three Berardius
species, with Indopacetus pacicus as the outgroup. See Materials and Methods for details regarding nucleotide
sequencing and tree construction.
Figure 10. Berardius minimus localities plotted against the B. bairdii distribution map (shaded area, as
described by Kasuya18). Circles show B. minimus localities. e white circle with a black X indicates the B.
minimus type locality, whereas the black circle with the white X indicates the B. bairdii type locality.
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SCIENTIFIC REPORTS | (2019) 9:12723 |
such as B. bairdii and B. arnuxii. It means adult size of B. minimus is essentially far smaller than the other two
Berardius species.
e molecular biology of B. minimus was previously discussed by Kitamura et al.6, and specic genome char-
acters were only identied in individuals collected from Hokkaido. However, we found a skull with B. minimus
characters in the collection of the USNM which was collected from the Unalaska Island in 1943. Additional
individuals were detected among the samples collected in the Aleutian area, and further analyses and consider-
ations were conducted and discussed by Morin et al.7. Further detailed analyses on Berardius species in both the
northern and southern hemispheres are needed to explain Berardius speciation processes.
e currently recorded B. minimus distribution is very limited and occurs between 40°N and 60°N, and
140°E and 160°W. ey have fairly dense cookie-cutter shark (Isistius brasiliensis) bites. e cookie-cutter shark
is understood to be a tropical to warm-temperate species and their northern limit in the western North Pacic is
reported to be 30°N to 43°N39. However, the southern limit of the B. minimus distribution might extend further
Although species identities of B. arnuxii and B. bairdii have been previously debated, we described another
species of this genus. However, it is unclear whether B. minimus speciation occurred before or aer the anti-
tropical split of B. arnuxii and B. bairdii. Additionally, the area where Berardius speciation took place should be
examined in the future.
Specimens examined. e specimens of this unknown species, which were collected in Hokkaido, are
listed in Table1. No live animals were used for the current research. Observations on the external appearance and
morphometrics, observations on the skeleton especially of the skull, skull morphology and measurements and
molecular phylogenetic analysis were conducted.
External morphology and measurements. External observations of the ve individuals of Berardius
minimus (three physically mature males, one subadult female, and a head of one neonate female) were made, and
the external morphometrics following previous studies32,40 (Tables6 and 7) were conducted on four B. minimus
(all physically mature males; Table1). Raw data examination revealed that body length and the ratio of beak
length-to-body length signicantly diered, and Welch’s t-test was applied to these variables.
Skeletal morphology and measurements of the skull. Observations of the skeleton, especially of the
skull, and skull measurements were made for 21 specimens (10 B. bairdii, seven B. arnuxii, and four B. minimus)
(Table2). Specimens are stored at the USNM, NMNS, MNHN, Natural History Museum of London (BMNH),
and Museo Acatushún (MA).
Multivariate analysis. To examine the dierence between the morphological features among species, a mul-
tivariate analysis was conducted. To describe the eect of the dierence of body size by species, a principal com-
ponent analysis (PCA) was conducted for 27 measurements shown in Table5 for 22 samples (four B. minimus, 10
B. bairdii, seven B. arnuxii) shown in Table3. For all variables, measured values using this analysis are indicated
in bold gothic.
Specimen ID M35131 M35206 M42012 M42610
Sex M F M M
V1 Body length from tip of snout to notch of ukes 660 621 662 690
V2 Tip of snout to tip of dorsal n 473 429 475 467.1
V3 Tip of snout to blow hole 65 68 77 53
V4 Length of snout 25 25.2 22.9 21.8
V5 Projection of lower jaw beyond tip of snout 5 6 5.1
V6 Tip of snout to angle of gape 36 35 44 38
V7 Tip of snout to centre of eye 59 63.5 60 53
V8 Tip of snout to anterior insertion of ipper 115 105 105 110
V9 Tip of snout to umbilicus 273 307 317.3
V10 Tip of snout to centre of genital aperture 432 425 461.5 464.3
V11 Tip of snout to anus 483 449 497 477
V12 Centre of eye to centre of ear 13 24.7 16.6
V13 Fluke length from anterior insertion to notch 55 56.5 60 54.6
V14 Fluke width from tip to tip 167 162 179 176.2
V15 Length of base of dorsal n 70 65 56.5 48
V16 Vertical height of dorsal n 25 22 22.5 27
V17 Maximum width of ipper 28 23.5 25.3 25.9
V18 Straight length of ipper from tip to anterior
insertion 77 48 85.2 92.8
Table 6. External measurements of Berardius minimus used for the comparison with B. bairdii.
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A linear discriminant analysis (LDA) was then conducted to compare species using the scores obtained from
the principal component analysis (PCA). Calculations were carried out using “prcomp” and “lda” function in R
Nucleotide sequence analysis and molecular phylogeny. e 18 mtDNA control region (CR) sequences
analysed (Table5) included sequences from three B. minimus specimens (Acc. Nos LC175771-LC175773 for
SNH12044, SNH12054, and SNH14016, respectively) and 15 previously reported sequences, which included seven
for B. bairdii (Kitamura et al.6, AB571999-AB572005), ve B. minimus (Kitamura et al.6, AB572006-AB572008,
updated complete sequences August 2016; and Morin et al.7, Acc. Nos KT936580-KT936581), two B. arnuxii
(Dalebout et al.16, Acc. Nos AF036229 and AY579532), and one Indopacetus pacicus (Kitamura et al.6, AB572012)
as an outgroup. I. pacicus was selected because it belongs to the same family but is in a rather distant genus, which
was inferred by a previous CR phylogenetic tree6. All the newly collected samples for the nucleotide sequence analy-
sis and molecular phylogeny were ocially transferred to the authors from the original sample holder, the Stranding
Network Hokkaido. Nucleotide sequencing of the complete mtDNA CR in the three B. minimus was performed
using primer pairs CRL (5-CAA CAC CCA AAG CTG GAA TTC T-3)6 and CRH2 (5-TAG ACA TTT TCA GTG
TCT TGC-3, which was newly designed for this study) for PCR amplication, and CRH (5-CCA TCG AGA TGT
CTT ATT TAA G-3)6 and LCR (5-GAC ATC TGG TTC TTA CTT CAG G-3)42 as internal sequencing primers.
CR sequence alignment was performed using CLUSTAL X43, and the output was inspected by eye following
the application of multiple alignment parameters in the program. All CR sequences were adjusted to the short
length of the B. arnuxii sequence, 430 bp (Dalebout et al.16, Acc. Nos AF036229 and AY579532), for multiple
sequence comparison and molecular phylogenetic analysis.
A molecular phylogenetic tree was constructed with 430-bp mitochondrial CR sequences of all analysed spe-
cies using the maximum likelihood algorithm in MEGA version 744 based on the Tamura 3-parameter model45
with gamma distribution (parameter = 0.2001), which was suggested to be the best nucleotide substitution model
based on a model test in this program. Bootstrap values were calculated by 1,000 replicates46.
Data Availability
Genbank Accession Numbers for sequences used in molecular phylogenetic analysis are listed in Table5. Materi-
als examined in this study and associated museum number are listed in Table1.
1. eeves, . ., Brent, S. S., Clapham, P. J., Powell, J. A. & Folins, P. A. National Audubon Society guide to marine mammals of the
world. Chanticleer Press, New Yor, NY (2002).
2. Committee on Taxonomy. List of marine mammal species and subspecies. Society for Marine Mammalogy, www., consulted on March 25, 2019 (2018).
3. Mead, J. G. & Brownell, . L. Jr. Order Cetacea. In Wilson, D. E. & eeder, D. M. eds Mammal species of the world: A taxonomic and
geographic reference, 3rd edition, pp. 723–743, e Johns Hopins University Press, Baltimore, MD (2005).
4. Omura, H., Fujino, . & imura, S. Beaed whale Berardius bairdi of Japan, with notes on Ziphius cavirostris. Scientic eports of
the Whales esearch Institute 10, 89–132 (1955).
5. asuya, T. Conservation biology of small cetaceans around Japan, University of Toyo Press, Toyo (in Japanese) (2011).
6. itamura, S. et al. Two genetically distinct stocs in Baird’s bea ed whale (Cetacea: Ziphiidae). Marine Mammal Science 29, 755–766
Measurements n Mean
(cm) SD
Measurement items
listed in Table6
V1 34 997.8 78.82
V2 22 703.5 68.89
V3 28 107.4 11.1
V4 29 58 8.02
V5 23 7.2 2.72
V6 27 62.2 6.78
V7 23 93.5 11.04
V8 24 160.4 20.19
V9 24 438 33.5
V10 23 641.8 57.23
V11 24 711.4 61.06
V12 22 21.7 1.79
V13 20 81.5 10.3
V14 10 271.9 15.44
V15 19 58.2 9.35
V16 20 25.1 2.92
V17 19 40.8 3.55
V18 16 123.6 7.56
Table 7. Measured external morphometrics characters for B. bairdii as described in previous studies32,40.
Content courtesy of Springer Nature, terms of use apply. Rights reserved
SCIENTIFIC REPORTS | (2019) 9:12723 |
7. Morin, P. A. et al. Genetic structure of the beaed whale genus Berardius in the North Pacic, with genetic evidence for a new
species. Marine Mammal Science. 33, 96–111 (2017).
8. Duvernoy, M. Mémoir sur les caractères ostéologiques des genres nouveaux ou des espèces nouvelles de cétacés vivants ou fossiles,
dont les squelettes entiers, ou les tétes seulement, sont consservés dans les galeries d’anatomie comparée du muséum d’histoire
naturelle. Annales des Sciences Naturelles, Ser. 3, partie Zoologique 15, 5–71 (1851).
9. Stejneger, L. Contributions to the history of the Commander Islands. No. 1-Notes on the natural history, including descriptions of
new cetaceans. In Proceedings of the United States National Museum 6, 58–89 (1883).
10. Malm, A. W. Selettdelar af hval insamlade under expeditionen med Vega 1878–1880. Bihang Till ungliga Svensa
Vetensapsaademiens Handlingar 8, 1–114 (1883).
11. True, F. W. An account of the beaed whales of the family Ziphiidae in the collection of the United States National Museum, with
remars of some specimens in other American museums. Bulletin of the United States National Museum 73, 1–89 (1910).
12. Davies, J. L. e antitropical factor in cetacean speciation. Evolution 17, 107–116 (1963).
13. asuya, T. Giant beaed whales. Berardius bairdii and B. arnuxii. In Perrin, W. F., Würsig, B. & ewissen, J. G. M. eds, Encyclopedia
of Marine Mamm als. Academic Press, San Diego, CA, 498–500 (2009).
14. Slipp, J. W. & Wile, F. e beaed whale Berardius on the Washington coast. Journal of Mammalogy 34, 105–113 (1953).
15. Mclachlan, G., Liversidge, . & Tietz, . M. A record of Berardius arnouxi from the south-east coast of South Africa. Annals of the
Cape Provincial Museums. Natural History5, 91–100 (1966).
16. Dalebout, M. L., Baer, C. S., Mead, J. G., Coccro, V. G. & Yamada, T. . A comprehensive and validated molecular taxonomy of
beaed whales, family Ziphiidae. Journal of Heredity 95, 459–473 (2004).
17. oss, G. J. B. e smaller cetaceans of the south east coast of Southern Africa. Annals of the Cape Provincial Museums Natural
History 15, 173–410 (1984).
18. asuya, T. Small Cetaceans of Japan. Exploitation and Biolog y. CC Press, Taylor & Francis, Boca aton (2017).
19. Andrews, . C. Berardius bairdii in Japan. Science, New Series 36, 902–903 (1912).
20. Nagasawa, . Nihon-san Tsuchiujira ni shu. Fu Aabou ujira (Two species of the genus Berardius, with some comments on
Ziphius). Doubutsugau Zasshi (Journal of Zoology, Japan) 25, 178–182 (in Japanese) (1913a).
21. anda, G. Nitto Gyofu. Sha, Edo (in Japanese) (1731).
22. anda, G. Nitto Gyofu. Sha, Edo (in Japanese) (1741).
23. Ohtsui, S. H. Geishiou, Sha, Edo (in Japanese) (1808).
24. Fuuyama, J. I. Hogeiai no Senausha Daigo Shinbē (Daigo Shinbe the Pioneer of Whaling in Japan), Nihon Shuppansha, Osaa
(in Japanese) (1943).
25. Oada, N. Nihon Doubutsu Soumourou (Catalogue of Vertebrated Animals of Japan), inodo, Toyo (in Japanese) (1891).
26. Montgelard, C., Catzeflis, F. M. & Douzery, E. Phylogenetic relationships of artiodactyls and cetaceans as deduced from the
comparison of cytochrome b and 12S rNA mitochondrial sequences. Molecular Biology and Evolution 14, 550–559 (1997).
27. Brisson, M.-J. egnum animale in classes IX. Distributum, sive synopsis methodica sistens generalem animalium distributionem in
classes IX, & duarum primarum classium, quadripedum scilicet & cetaceorum, particularem divisionem in ordines, sectiones,
genera, & species. Cum brevi cujusque speciei descriptione, citationibus auctorum de iis tractantium, nominibus eis ab ipsis &
nationibus impostis, nominibusque vulgaribus. eodorum Haa, Lugduni Batavorum (Leiden) (1762).
28. Flower, W. H. Notes on the seletons of whales in the principal museums of Holland and Belgium, with descriptions of two species
apparently new to science. Proceedings of the zoological Society of London 1864, 384–420 (1864).
29. Gray, J. E. Notices of a new genus of delphinoid whales from the Cape of Good Hope, and of other cetaceans from the same seas.
Proceedings of the zoological Society of London 1865, 522–529 (1865).
30. Hale, H. M. Occurrence of the whale Berardius arnuxi in Southern Australia. ecords of the South Australian Museum 14, 230–243
31. Balcomb, . C. Baird’s beaed whale Berardius bairdii Stejneger, 1883: Arnoux’s beaed wha le Berardius arnuxii Duvernoy, 1851. In
idgway, S. H. & Harrison, . eds, iver Dolphins and the Larger Toothed Whales 4, Handboo of Marine Mammals, Academic Press,
San Diego, 261–288 (1989).
32. ishiro, T. Geographical variations in the external body proportions of Baird’s beaed whales (Berardius bairdii) o Japan. Journal
of Cetacean esearch and Management 9, 89–93 (2007).
33. Ono, H. & imura, M. An Osteological Study on the Sull of Mesoplodon Stranded on itahiyama Beach, Japan. In Professor Aira
ASUGAI Memorial Volume, Executive Committee of the etirement Memorial of Professor Aira ASUGAI, Sapporo, 115–135
34. Ishiawa, H. Stranding ecord in Japan (collected during the year 2013). Shimonosei Marine Science eport 2, 21–43 (in Japanese)
35. Heptner, V. G., Chapsii, . ., Arsenev, V. A. & Soolov, V. E. Mammals of the Soviet Union, Volume II, Part 3: Pinnipeds and
toothed whales, Smithsonian Institution Libraries and the National Science Foundation, Washington, DC (1996). (Originally
published in ussian by Vysshaya Shola Publishers, Moscow, 1976).
36. Scheinin, A. P. et al. Gray whale (Eschrichtius robustus) in the Mediterranean Sea: anomalous event or early sign of climate-driven
distribution change? Marine Biodiversity ecords 4, e28 (2011).
37. Elwen, S. H. & Gridley, T. Gray whale (Eschrichtius robustus) sighting in Namibia (SE Atlantic) - rst record for southern hemisphere.
International Whaling Commission Scientic Committee SC/65a/BG30 (2013).
38. asuya, T. Giant beaed whales. In Perrin, W. F., Würsig, B. & ewissen, J. G. M. eds, Encyclopedia of Marine Mammals, Academic
Press, San Diego, CA, 519-522 (2002).
39. Sasai, H. et al. Habitat dierentiation between sei (Balaenoptera borealis) and Bryde’s whales (B. brydei) in the western North
Pacic. Fisheries Oceanography 22, 496–508 (2013).
40. Norris, . S. & Prescott, J. H. Observations on Pacific cetaceans of California and Mexican waters. University of California
Publications in Zoology 63, 291–402 (1961).
41.  Core Team. : A Language and Environment for Statistical Computing.  Foundation for Statistical Computing, Vienna, Austria
42. Xiong, Y., Brandley, M. C., Xu, S., Zhou, . & Yang, G. Seven new dolphin mitochondrial genomes and a time-calibrated phylogeny
of whales. BMC Evolutionary Biology 9, 1–13 (2009).
43. ompson, J. D., Gibson, T. J., Plewnia, F., Jeanmougin, F. & Higgins, D. G. e ClustalX windows interface: Flexible strategies for
multiple sequence alignment aided by quality analysis tools. Nucleic Acids esearch 25, 4876–4882 (1997).
44. umar, S., Stecher, G. & Tamura, . MEGA7: Molecular Evolutionary Genetics Analysis version 7.0 for bigger datasets. Molecular
Biology and Evolution 33, 1870–1874 (2015).
45. Tamura, . Estimation of the number of nucleotide substitutions when there are strong transition-transversion and G+ C-content
biases. Molecular Biology and Evolution 9, 678–687 (1992).
46. Felsenstein, J. Condence limits on phylogenies: An approach using the bootstrap. Evolution 39, 783–791 (1985).
Content courtesy of Springer Nature, terms of use apply. Rights reserved
SCIENTIFIC REPORTS | (2019) 9:12723 |
We greatly appreciate the many people who helped us nd and collect stranded whales, which were in remote
localities in most instances. Field work was supported by many enthusiastic people, including Hal Sato, Minako
Kurasawa, Mari Kobayashi, Yoshikazu Uni (Tokyo University of Agriculture), Kenji Sakurai (Fisher of Rausu
FCA), Mutsuo Goto (ICR), Hajime Ishikawa (Shimonoseki Academy of Marine Science) and Yasushi Shimizu
(Sarufutsu-mura FCA), who signicantly contributed. For analysis of existing specimens, we thank Richard Sabin
(Natural History Museum of London), Cécile Callou (le Museum Nationalle d’Histoire Naturelle), Rae Natalie
Goodall (Museo Acatushún de Aves y Mamíferos Marinos Australes), Charles W. Potter (United States National
Museum of Natural History), and Dee Allen (Marine Mammal Commission). Moreover, we also are grateful
to the editorial members including two anonymous referees for helpful suggestions to the earlier version, and
Mallory Eckstut, PhD, from Edanz Group ( for editing a dra of this manuscript. is
work is partly supported by JSPS KAKENHI Grant Number JP25340105 (Y.T., T.K.Y.), JP25281008 (Y.T., T.K.Y.,
T.M.), JP26450255 (T.M., A.M.) and JP18J30013 (A.M.).
Author Contributions
T.K.Y. designed the study, conducted field work and morphological measurements, and wrote the paper.
Y.T. conducted field work and recorded morphological measurements. S.K. and S.A. conducted molecular
phylogenetic analysis. A.M. conducted eld work, organised stranding records, and edited the manuscript. J.G.M.
assisted with measurements and made systematic discussions. T.F.M. conducted morphological analysis, eld
work, organised stranding records, and nalised the manuscript. All authors commented on the manuscript.
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... Morin et al. (2017) also demonstrated strong genetic differences between the two forms, as well as between the "black form" and B. arnuxii; moreover, they found that the "black form" differs from the two recognized Berardius species to a greater degree than they do from each other (Morin et al., 2017). Finally, Yamada et al. (2019) published the formal description of the new species (Berardius minimus), which was named Sato's beaked whale in Brownell and Kasuya (2021). Fedutin et al. (2020) identified three Berardius minimus specimens among stranded beaked whales found on Sakhalin and the southern Kuril Islands, including Kunashir Island ( Figure 1). ...
... All of the genetic samples analyzed so far from the above studies were taken from dead animals, and the purported observations of Sato's beaked whales at sea were not confirmed genetically (Yamada et al., 2019). Here, we report observations of Sato's beaked whales in Nemuro Strait (Figure 1) with species identification confirmed from a biopsy sample taken from an individual in one of the groups. ...
... It is not yet clear whether the method is fully applicable to Sato's beaked whales. Also, the density of cookie-cutter shark scars seemed to be noticeably higher in Sato's beaked whales than in Baird's beaked whales (which was also noted by Yamada et al., 2019). Even juveniles with an estimated age of 2-4 years had scar density comparable to that of adult Commander Islands Baird's beaked whales. ...
Beaked whales (Family Ziphiidae, Odontoceti, Cetacea) are one of the least studied groups of cetaceans. Their preference for shelf slope or deep ocean waters, long dives, low surface profile, elusiveness, and lack of visible blow in most species makes them difficult to spot, especially in rougher sea-state conditions. Due to these features, some species of beaked whales, including the third member of the genus Berardius, were discovered only recently using genetic analyses. Until recently, two Berardius species were officially recognized: Baird's beaked whale (Berardius bairdii) in the North Pacific and Arnoux's beaked whale (Berardius arnuxii) in the Southern Hemisphere. However, for decades, Japanese whalers have recognized two forms of Berardius off Hokkaido: the more common, slate-gray Baird's beaked whale, and another, smaller and darker form known as karasu (meaning “crow” or “raven”; Kasuya, 2017; Omura et al., 1955). Kitamura et al. (2013) reported that three specimens with morphological features indicative of that smaller “black form” had significantly different mitochondrial control region haplotypes from 64 specimens assigned to the “gray form.” Morin et al. (2017) also demonstrated strong genetic differences between the two forms, as well as between the “black form” and B. arnuxii; moreover, they found that the “black form” differs from the two recognized Berardius species to a greater degree than they do from each other (Morin et al., 2017). Finally, Yamada et al. (2019) published the formal description of the new species (Berardius minimus), which was named Sato's beaked whale in Brownell and Kasuya (2021). Fedutin et al. (2020) identified three Berardius minimus specimens among stranded beaked whales found on Sakhalin and the southern Kuril Islands, including Kunashir Island (Figure 1). All of the genetic samples analyzed so far from the above studies were taken from dead animals, and the purported observations of Sato's beaked whales at sea were not confirmed genetically (Yamada et al., 2019). Here, we report observations of Sato's beaked whales in Nemuro Strait (Figure 1) with species identification confirmed from a biopsy sample taken from an individual in one of the groups.
... Moreover, the extinction risk assignment of cetaceans is entirely based on population size (Criteria A and C), which could introduce circularity into correlative analyses. The above data were available for almost all cetaceans with the exception of Berardius minimus (NT), a newly described species of the genus Berardius in 2019 (Yamada et al., 2019). We hence excluded this species, leaving a total of 80 cetacean species for further analyses. ...
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Despite that cetaceans provide significant ecological contributions to the health and stability of aquatic ecosystems, they are highly endangered with nearly one-third of species assessed as threatened with extinction. Nevertheless, to date, few studies have explicitly examined the patterns and processes of extinction risk and threats for this taxon, and even less between the two subclades (Mysticeti and Odontoceti). To fill this gap, we compiled a dataset of six intrins ic traits (active region, geographic range size, body weight, diving depth, school size and reproductive cycle), six environmental factors relating to sea surface temperature and chlorophyll concentration, and two human-related threat indices that are commonly recognized for cetaceans. We then employed phylogenetic generalized least square (PGLS) models and model selection to identify the key predictors of extinction risk in all cetaceans, as well as in the two subclades. We found that geographic range size, sea surface temperature and human threat index were the most important predictors of extinction risk in all cetaceans and in odontocetes. Interestingly, maximum body weight was positively associated with the extinction risk in mysticetes, but negatively related to that for odontocetes. By linking seven major threat types to extinction risk, we further revealed that fisheries bycatch was the most common threat, yet the impacts of certain threats could be overestimated when considering all species rather than just threatened ones. Overall, we suggest that conservation efforts should focus on small-ranged cetaceans and species living in warmer waters or under strong anthropogenic pressures. Moreover, further studies should consider the extinction risk of species when superimposing risk maps and quantifying risk severity. Finally, we emphasize that mysticetes and odontocetes should be conserved with different strategies, because their extinction risk patterns and major threat types are considerably different. For instance, large-bodied mysticetes and small-ranged odontocetes require special conservation priority.
... The ziphiid genus Mesoplodon is the most diverse, accounting for 15 of the 22 species of the family (Cappozzo et al. 2005;McLeod et al. 2006;Pitman 2009;McLeod 2009McLeod , 2017Yamada et al. 2019) McLeod et al. 2006). Six species of Mesoplodon have been reported in Chile: M. densirostris, M. grayi, M. hectori, M. layardii, M. peruvianus, and M. traversi (Canto and Yáñez 2009;D'Elía et al. 2020). ...
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Information collected from a complete female juvenile individual of Gray's beaked whale (Mesoplodon grayi) stranded on the Guanaqueros coast, Coquimbo Region in Chile (30°S) is provided. Difficulties to differentiate specimens of Gray's beaked whale and Hector's beaked whale (M. hectori) are discussed based on the use of diagnostic phenotypic characters, such as differences in color patterns and position of teeth on the lower jaw. The identification of the studied specimen as Gray's beaked whale was supported by a detailed review of cranial characters and molecular analyses. Finally, we provide an updated list containing all known Chilean records for this species. Se proporciona información del registro más completo de Mesoplodon grayi (Ziphiidae) que se conoce para Chile y que corresponde a una hembra juvenil varada en la costa de Guanaqueros, Región de Coquimbo (30°S). Se discuten los problemas de determinación de Mesoplodon grayi con respecto a M. hectori en base a la utilización de caracteres fenotipicos generales como patrones de coloración. La asignación a Meso-plodon grayi se apoyó en la revisión detallada de caracteres craneales y un análisis molecular. Además, se presenta un listado actualizado con todos los registros conocidos para esta especie en las costas de Chile.
... The extant members of the family Ziphiidae (beaked whales) are known as medium-to large-sized, open-ocean cetaceans that display remarkable adaptations for diving into deep waters, detecting the prey (predominantly squid) by using their sonar system, and finally capturing their food items by means of suction. Due to their elusive behaviour that largely prevents direct observations in natural habitats, little is known about beaked whales in spite of their being the second most diverse family of cetaceans after Delphinidae (ocean dolphins) (Mead, 2018;Yamada et al., 2019;Carroll et al., 2021). Distinctive cranial characters of the ziphiids include an elevated vertex that is anterolaterally bordered by well-distinct premaxillary crests, a wide and elongated Abbreviations: fr, frontal; md, mandible; mx, maxilla; na, nasal; pmx, premaxilla; soc, supraoccipital; sq, squamosal; tf, temporal fossa. ...
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The East Pisco Basin is one of the forearc basins that formed during the Cenozoic along the coast of Peru due to the subduction of the Farrallon-Nazca plate beneath the South American plate. The sedimentary fi ll of this basin is extensively exposed along the coastal Ica Desert, and includes a succession of Eocene to Pliocene marine sediments that account for a ~50-myr-long history of semi-continuous deposition. These rocks are characterized by an outstanding fossil content that remarkably contributed to our understanding of the evolutionary history of the main groups of Cenozoic marine vertebrates. In the Ica desert, the most common and signifi cant vertebrate remains belong to cetaceans. Knowledge on the fossil cetaceans of the East Pisco Basin has grown dramatically in the last fi fteen years thanks to several international research projects involving, among many others, the authors of the present article. These research eff orts have led to the discovery of several hundred fossil skeletons, the most signifi cant of which have been collected, prepared and partly published. Furthermore, interdisciplinary studies were also conducted in order to provide a high resolution chronostratigraphic framework for this fossil record. Remarkable cetacean specimens (42.6 Ma) Yumaque strata are home to the quadrupedal protocetid archaeocete Peregocetus pacifi cus, which documents the fi rst arrival of cetaceans in the Pacifi c Ocean. Geologically younger (36.4 Ma) Yumaque deposits have yielded the holotype skeleton of Mystacodon selenesis, the oldest mysticete ever found. This ancestor of the modern baleen whales had a skull provided with a complete dentition and retained hindlimbs, albeit reduced in size. In the Otuma Formation, a nine-m-long basilosaurid (Cynthiacetus peruvianus) has been discovered. The Chilcatay Formation records the fi rst great radiation of the odontocetes, represented by Inticetidae (Inticetus vertizi), basal Platanidelphidi (Ensidelphis riveroi), Squalodelphinidae (Furcacetus fl exirostrum, Huaridelphis raimondii, Macrosqualodelphis ukupachai and Notocetus vanbenedeni), Platanistidae (aff. Araeodelphis), Physeteroidea (Rhaphicetus valenciae and cf. Diaphorocetus), Chilcacetus cavirhinus, indeterminate Eurinodelphinidae, and Kentriodontidae (Kentriodon). Overall, this roughly coeval assemblage displays a considerable disparity in terms of skull shape and body size that is possibly related to the development of diff erent trophic strategies, ranging e.g., from suction to raptorial feeding. In the Pisco Formation, starting from P0, the baleen-bearing whales (Chaeomysticeti) represent the most frequent cetacean fossils (only a few mysticetes are known from the Chilcatay strata). Two chaeomysticete lineages are found in the Pisco Formation: Cetotheriidae (from Tiucetus rosae in P0 to Piscobalaena nana in P2) and Balaenopteroidea (from Pelocetus in P0 to several undescribed species of Balaenopteridae in P2, testifying to a progressive trend toward gigantism). Odontocetes are rare in P0, the "kentriodontid" Incacetus broggii being the only species described from these strata, but they become more abundant and diverse in P1 and P2. In P1, the commonest toothed whale is Messapicetus gregarius, a member of Ziphiidae featuring an extremely elongated rostrum and a complete set of functional teeth. Another ziphiid from P1 is Chimuziphius coloradensis, known only from the fragmentary holotype cranium. The P1 strata also record the appearance of the crown Delphinida, with the superfamily Inioidea being represented by two small pontoporiids (Brachydelphis mazeasi and Samaydelphis chacaltanae) and one iniid (Brujadelphis ankylorostris). Moreover, P1 is also home to the stem physeteroid Livyitan melvillei; featuring a three-m-long skull and teeth reaching 36 cm in length, L. melvillei was one of the largest raptorial predators and, possibly, the biggest tetrapod bite ever found. Acrophyseter is another macroraptorial sperm whale, distinctly smaller than L. melvillei, known from both P1 and P2. Even smaller in size are the kogiids Platyscaphokogia landinii and Scaphokogia cochlearis, both of which are known from the upper strata of P2. The same allomember is also home to the ziphiids Chavinziphius maxillocristatus and Nazcacetus urbinai, the "kentriodontids" Atocetus iquensis and Belenodelphis peruanus, and undescribed members of Phocoenidae.
... Cozzuol et al., 2013), marine mammals (e.g. Yamada et al., 2019), and hundreds of insect species at a time (Srivathsan et al., 2019) testify to our ignorance of these underexplored ecosystems. However, there are new species still hiding in our proverbial backyards (e.g. ...
Gall wasps (Hymenoptera: Cynipidae) specializing on live oaks in the genus Quercus (subsection Virentes) are a relatively diverse and well-studied community with 14 species described to date, albeit with incomplete information on their biology, life history and genetic structure. Incorporating an integrative taxonomic approach, we combine morphology, phenology, behaviour, genetics and genomics to describe a new species, Neuroterus valhalla sp. nov.. The alternating generations of this species induce galls on the catkins and stem nodes of Quercus virginiana and Quercus geminata in the southern United States. We describe both generations in the species’ life cycle, and primarily use samples from a population in the centre of Houston, Texas, thus serving as an example of the undescribed biodiversity still present in well-travelled urban centres. In parallel, we present a draft assembly of the N. valhalla genome providing a direct link between the type specimen and reference genome. The genome of N. valhalla is the smallest reported to date within the tribe Cynipini, providing an important comparative contrast to the otherwise large genome size of cynipids. While relatively small, the genome was found to be composed of >64% repetitive elements, including 43% unclassified repeats and 11% retrotransposons. A preliminary ab initio and homology-based annotation revealed 32,005 genes, and a subsequent orthogroup analysis grouped 18,044 of these to 8186 orthogroups, with some evidence for high levels of gene duplications within Cynipidae. Amitochondrial barcode phylogeny linked each generation of the new species and a phylogenomic ultraconserved element (UCEs) phylogeny indicates that the new species groups with other Nearctic Neuroterus. However, both phylogenies present the genus Neuroterus in North America as polyphyletic.
... There are also reports that smaller whales, such as members of the genus Berardius, washed ashore of Lamalera island. Whales of the species B. minimus, a newly named species, can also be found in the local waters of Hokkaido, Japan (Yamada et al 2019). Information on the distribution and ecology of whales is still limited, especially for regions in Indonesia, because the distribution of species and their behavior is unknown. ...
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There has been little information and no comprehensive study made on whales (Cetacean) in Indonesia, particularly in the region of the Savu sea. Alor Island and Lamalera Island are a part of the Savu sea region. Savu sea is the main migratory route for cetaceans. The research aims to determine the DNA makeup of whales in the Savu sea region, both stranded and caught, and to perform a DNA analysis of their stomach content to determine their natural diet. The research was conducted from May to September 2020. The results of the DNA analysis of stranded whales found the species of Mesoplodon densirostris. In the stomach of the stranded whale, a parasitic worm of Ancylostoma ceylanicum was found. DNA analysis of the whales caught by fishermen in Lamalera Island was Physeter catodon. The squid Sepioteuthis lessoniana is determined to be the natural diet of the whales in this region. Sepioteuthis lessoniana was determined to be the natural diet of the whales.
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Mlynarek introduces the important ecological and agricultural role of flies as pollinators.
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Beaked whales are cryptic and difficult to study species, often distributed in deep offshore waters and only briefly visible at the surface. A diverse range of cetacean species has been documented in the Bay of Biscay, including several species of beaked whales. However, little is known about how persistent their presence is. Citizen science data collected during ferry-based surveys between 2006 and 2018 were analysed to investigate how encounter rates varied across space and time, and their drivers for beaked whale species. Approximately 244,400 km were surveyed, and there were 419 encounters with beaked whales recorded including Cuvier’s beaked whales, ( n = 260), Northern bottlenose whales ( n = 19), Sowerby’s beaked whales ( n = 13), and True’s beaked whales ( n = 1). Generalized Additive Models revealed that encounters were generally more frequent in the southern bay, on northern facing slopes, with all species except Sowerby’s showing a preference for both deep waters and shallow shelf waters. Animals were recorded in each of the eight surveyed months, suggesting that beaked whales may be present year-round, with increased encounter rates in summer months. This study is the first to indicate that beaked whales may persist in this area throughout the year, which is key information for appropriate management.
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Beaked whales (Ziphiidae) are a diverse family of odontocetes (toothed whales) adapted to life in the open ocean. Their deep diving behavior and apparent low abundance make extant Ziphiidae hard to study resulting in a relatively poor understanding of their biology. Fossil data aid a better understanding of their evolution and lifestyle. The Miocene of the southern North Sea Basin is a rich source of fairly well preserved fossil ziphiid taxa. Here, we describe new ziphiid fossils from the Dutch part of the Westerschelde estuary: a well-preserved cranium of Ziphirostrum marginatum du Bus, 1868 and some peculiar rostral fossils that represent the first Dutch record of Aporotus recurvirostris du Bus, 1868.
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We present the latest version of the Molecular Evolutionary Genetics Analysis (MEGA) software, which contains many sophisticated methods and tools for phylogenomics and phylomedicine. In this major upgrade, MEGA has been optimized for use on 64-bit computing systems for analyzing bigger datasets. Researchers can now explore and analyze tens of thousands of sequences in MEGA. The new version also provides an advanced wizard for building timetrees and includes a new functionality to automatically predict gene duplication events in gene family trees. The 64-bit MEGA is made available in two interfaces: graphical and command line. The graphical user interface (GUI) is a native Microsoft Windows application that can also be used on Mac OSX. The command line MEGA is available as native applications for Windows, Linux, and Mac OSX. They are intended for use in high-throughput and scripted analysis. Both versions are available from free of charge.
The recently-developed statistical method known as the "bootstrap" can be used to place confidence intervals on phylogenies. It involves resampling points from one's own data, with replacement, to create a series of bootstrap samples of the same size as the original data. Each of these is analyzed, and the variation among the resulting estimates taken to indicate the size of the error involved in making estimates from the original data. In the case of phylogenies, it is argued that the proper method of resampling is to keep all of the original species while sampling characters with replacement, under the assumption that the characters have been independently drawn by the systematist and have evolved independently. Majority-rule consensus trees can be used to construct a phylogeny showing all of the inferred monophyletic groups that occurred in a majority of the bootstrap samples. If a group shows up 95% of the time or more, the evidence for it is taken to be statistically significant. Existing computer programs can be used to analyze different bootstrap samples by using weights on the characters, the weight of a character being how many times it was drawn in bootstrap sampling. When all characters are perfectly compatible, as envisioned by Hennig, bootstrap sampling becomes unnecessary; the bootstrap method would show significant evidence for a group if it is defined by three or more characters.
There are two recognized species in the genus Berardius, Baird's and Arnoux's beaked whales. In Japan, whalers have traditionally recognized two forms of Baird's beaked whales, the common “slate-gray” form and a smaller, rare “black” form. Previous comparison of mtDNA control region sequences from three black specimens to gray specimens around Japan indicated that the two forms comprise different stocks and potentially different species. We have expanded sampling to include control region haplotypes of 178 Baird's beaked whales from across their range in the North Pacific. We identified five additional specimens of the black form from the Aleutian Islands and Bering Sea, for a total of eight “black” specimens. The divergence between mtDNA haplotypes of the black and gray forms of Baird's beaked whale was greater than their divergence from the congeneric Arnoux's beaked whale found in the Southern Ocean, and similar to that observed among other congeneric beaked whale species. Taken together, genetic evidence from specimens in Japan and across the North Pacific, combined with evidence of smaller adult body size, indicate presence of an unnamed species of Berardius in the North Pacific.
This chapter discusses the characteristics, taxonomy, distribution, abundance, and ecology of giant beaked whales, or Berardius bairdii and B. arnuxii. These two species are the largest members of the family Ziphiidae. Currently recognized morphological differences between the two species are slight and limited to smaller adult size in Arnoux's beaked whale (8.5-9.75 m vs. 9.1-11.1 m) and possible differences in flipper size and in the shape of nasal bones and vomer. Condylobasal lengths of skulls of adult Arnoux's beaked whales range from 1174-1420 mm, and those of Baird's beaked whale are 1343-1524 mm. Arnoux's beaked whales inhabit vast areas of the Southern Hemisphere outside of the tropics, from the Ross Sea at 78°S to Sao Paulo (24°S), northern New Zealand (37°S), South Africa (31°S), and southeastern Australia (29°S). Baird's beaked whales inhabit the temperate North Pacific and adjacent seas, mainly deep waters over the continental slope. The northern limits are at Cape Navarin (62°N) in the Bering Sea and in the central Okhotsk Sea (57°N), where they occur even in shallow waters of 200-1000 m. On the American side they usually occur north of northern Baja California (30°N), but there are records from La Paz (24°) in the southern Gulf of California. The southern limits on the Asian side are at 36°N on the Japanese coast in the Sea of Japan and at 34°N on the Pacific coast. They occur year-round in the Okhotsk Sea and the Sea of Japan, including the drift ice area of the former. A vagrant was taken off the Chinese coast (30°N).