Genetic diversity in wild and reared populations of the Japanese bitterling, Tanakia tanago
(Cyprinidae)
Hitoshi Kubota and Katsutoshi Watanabe
Abstract
The Japanese bitterling Tanakia tanago is an endangered cyprinid species, thus
captive breeding programs being conducted in various facilities as ex-situ conservation. To
examine the genetic diversity in a wild and three reared populations, and its changes during the
process of captive breeding, sequences of the mitochondrial cytochrome b gene and control
region were determined. The wild population, collected in 1993, was monomorphic. Although
the reared population which originated from the wild population was almost monomorphic, a
rare haplotype, distinct from all others by a relatively large sequence divergence, was also
observed. In the other reared populations, some degree of genetic diversity had been maintained.
A reared hybrid population, which originated from a mixture of three distinct populations,
showed the greatest genetic diversity. These results suggest considerable genetic diversity within
and among populations of T. tanago in the past. Although a loss of genetic diversity was
observed in some year-classes of reared populations, there was no tendency for genetic diversity
to decrease as a result of captive breeding, probably because offspring were obtained from
multi-year-class parents in the captive breeding program. Accordingly, this breeding method
should be appropriate for conserving the genetic diversity of T. tanago.
Key words
Tanakia tanago ･ Genetic diversity ･ Endangered fish ･ Mitochondrial DNA
(mtDNA) ･ Ex-situ conservation
Redescription of the East Asian bagrid catfish, Pseudobagrus kyphus Mai,
1978, and a new record from China
Katsutoshi Watanabe, Chun-Guang Zhang, and Ya-Hui Zhao
Abstract
A small species (< 90 mm SL) of the bagrid catfish, Pseudobagrus kyphus Mai, 1978,
1
originally described from northern Vietnam, is newly recorded from China and redescribed in
detail. The species is distributed in rivers flowing into Beibu Gulf (Gulf of Tonkin); i.e., the Song
Hong River basin in northern Vietnam, and rivers on the southern side of Mts. Shiwan-Dashan in
southernmost Guangxi Zhuangzu Autonomous Region, China. Partial nucleotide sequences of
the mitochondrial DNA are also described and compared among the populations.
Key words Bagridae · Siluriformes · Vietnam · Southern China · Mitochondrial DNA (mtDNA)
大分県安心院盆地の鮮新統津房川層から産出したギギ科化石
渡辺勝敏・北林栄一
Abstract
Morphological features of a fossil bagrid specimen collected from the Pliocene
Tsubusagawa Formation, Kami-era, Innai, Oita Prefecture, were described and compared
with fossil and extant East Asian bagrids.
The fossil specimen was the spine of a right
pectoral fin, lacking the tip, with strong serrations on the posterior edge and small but
distinct serrations on the anterior edge.
Numerous striations without granular
ornamentation ran longitudinally on the spine surface. The characteristics of the fossil
specimen were most similar to those of extant P. aurantiacus, distributed in western and
southern Kyushu, Japan, and the closely-related P. taeniatus, distributed in the Yangtze
River system, China, although there remained the possibility that the fossil spine was of P.
nudiceps, which is presently distributed in northeastern Kyushu (including the fossil
locality), Shikoku and western Honshu, Japan.
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Channa nox, a new channid fish lacking a pelvic fin from Guangxi,
China
Chun-Guang Zhang, Prachya Musikasinthorn, and Katsutoshi Watanabe
Abstract
A new species of channid fish, genus Channa, is described from 7 specimens
collected from the vicinity of Hepu, Guangxi Province, southern China.
The new species,
Channa nox, is distinguished from all other channid species by the following combination of
characters: absence of pelvic fins, small rounded head (22.1–26.8 %SL), narrow interorbital
width (19.6–26.7 %HL), short snout length (3.6–5.1 %SL), predorsal and prepectoral lengths
(26.9–28.4 %SL and 24.8–28.3 %SL, respectively), 47–51 dorsal fin rays, 31–33 anal fin rays,
55–63 lateral line scales, 5.5–6.5 scales above lateral line, 9–13 cheek scales, 53–55 total
vertebrae, 1 or 2 scale(s) on each side of lower jaw undersurface, the black upper half of body
with 8–11 irregular (often anteriorly-pointed V-shaped) bands or blotches, a large white-rimmed
black ocellus on caudal peduncle and sparse white spots on the dark brown body and dorsal and
caudal fins, as well as shape of the hyomandibular process of the suprabranchial organs.
Channa nox is sympatrically distributed with its morphologically most similar congener, C.
asiatica.
Key words
Channidae · Guangxi · Hepu · China · New species
福井県嶺南地方を流れる南川水系の淡水魚類
松宮由太佳・渡辺勝敏・井口恵一朗・岩田祐士・山本軍次・西田
睦
Freshwater-fish fauna of the Minami River System, Reinan Region, Fukui Prefecture,
Japan, was investigated in 1998. Forty-five species in 14 families (including those
newly recorded, such as Rhinogobius flumineus) were identified in the present research.
Combined with data previously reported, a total of 55 species in 16 families, which
included 36 primary and diadromous freshwater species (11 families), composed the fish
fauna that could be considered naturally distributed in this river system. Compared to
the richer fish fauna in western Japan regions, that of the Minami River System,
3
representative of the Reinan Region, is poorer, and composed of peripheral fish fauna.
The construction of many weirs and dams along the river system have prevented fish
migration, causing more or less distinct fish assemblages to form in each of the upper,
middle and lower reaches. Also, a number of species which inhabit small tributaries
and/or irrigation channels in the Minami River System, such as Tanakia limbata,
Acheilognatus tabira sp.1 (sensu Hosoya, 1993), Lefua echigonia, Oryzias latipes, and
the 'nagare-hotokedojo' L. sp. (sensu Hosoya, 1993), have been threatened with
extinction.
Aggressive mimicry in the intra-populational color variation of the Tanganyikan
scale-eater Perissodus microlepis (Cichlidae)
Michio Hori and Katsutoshi Watanabe
Synopsis
A color morph of the Tanganyikan scale-eater, Perissodus microlepis (Cichlidae),
considered to be an example of aggressive mimicry, is reported from the rocky littoral
area at the southern end of Lake Tanganyika, Zambia. The anal fin of the morph is
yellow, instead of the usual dark or transparent condition, being closely similar to that of
the gregarious cyprichrominine cichlids, Cyprichromis leptosoma species complex and
Paracyprichromis nigripinnis, abundant in the area.
The color morph of Perissodus
microlepis was observed to mingle with and attack shoals of the prey-model.
About
24 % of P. microlepis observed in less than 15 m depth at Kasenga Point were the
yellow-fin type. The color variation, which is likely associated with a variation in
feeding mode within this population, probably evolved and has been maintained by the
local community structure, which included abundant cyprichrominine fishes.
Key words:
Cyprichromis leptosoma, Paracyprichromis nigripinnis, exploitative
mutualism
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Phylogenetic relationships of the Japanese minnows, Pseudorasbora (Cyprinidae), as
inferred from mitochondrial 16S rRNA gene sequences
Katsutoshi Watanabe Kei'ichiroh Iguchi Kazumi Hosoya and Mutsumi Nishida
Abstract
The phylogenetic relationships among three Pseudorasbora fishes
(Cyprinidae, Sarcocheiichthyinae) occurring in Japan (P. parva, P. pumila pumila and P.
pumila subsp. sensu Nakamura [1963]) were inferred from nucleotide sequences of the
mitochondrial 16S rRNA gene.
The sequences, of 1240 bp, were determined and
compared for 22 specimens from 2–8 populations for each taxon, with a single
Pungtungia herzi specimen as an outgroup.
A total of 171 sites (13.8%) were variable
among the specimens, but only 0–2 sites within each population.
relationships
estimated
by
neighbor-joining,
The phylogenetic
maximum-parsimony
and
maximum-likelihood methods confirmed a sister relationship between the two P. pumila
subspecies, with a high level of confidence. However, their genetic distinction from
each other (4.1±0.4SD % sequence difference on average) was at a level similar to that
between them and P. parva (5.9±0.5%).
The geographic distribution of the two P.
pumila subspecies, which are separated by the Fossa Magna region, suggests that the
genetic divergence of the two subspecies originated from a vicariant process separating
the freshwater ichthyofaunas of eastern and western Honshu.
Pseudorasbora parva
populations were divided into two genetic groups (1.8±0.2% sequence difference), one
group comprising continental and part of the Japanese populations, and the other the
remaining Japanese populations.
This suggests that at least two genetically divergent
lineages had been originally distributed in Japan, but a strong possibility remains that the
present situation has resulted from artificial transplantation.
Key words.—Pseudorasbora; Cyprinidae; mitochondrial DNA; 16S rRNA; molecular
phylogeny
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Fossil bagrid catfishes from Japan and their zoogeography,
with description of a new species, Pseudobagrus ikiensis
Katsutoshi Watanabe & Teruya Uyeno
Abstract
Morphological characteristics of fossil bagrid catfishes from six
Miocene to Pleistocene localities in Japan are described. A new species of the Middle
Miocene bagrid, Pseudobagrus ikiensis, is described, based on five nearly complete
specimens (ca. 19 cm SL) and one half-body specimen from the Chojabaru Formation
(15 Ma) of the Iki Group in Nagasaki Prefecture. The species is diagnosed by a unique
combination of characters: 14–16 anal fin rays, 44–47 vertebrae, deeply forked caudal fin,
pectoral spines with serrations on the anterior edge and supraoccipital process extending
to the first pterygiophore of the dorsal fin.
Pseudobagrus ikiensis is morphologically
close to the extant P. fulvidraco, which is widely distributed in China, Siberia and the
Korean Peninsula, suggesting that both lineages had appeared by the Middle Miocene.
All other fossil specimens are from the Pliocene (3–4 Ma) Ueno Formation (lowest
Kobiwako Group, Ohyamada, Mie Pref.) and Tokai Group (Tsu, Mie Pref.), and
Pleistocene cave deposits (Inasa, Shizuoka Pref., Mine, Yamaguchi Pref. and Kanogawa,
Ehime Pref.). These are incomplete, comprising mainly dorsal and pectoral spines.
Being indistinguishable from the extant P. nudiceps, they are thus considered to be
included in that lineage. Although the geological distribution of these Plio-Pleistocene
fossils nearly overlaps that of the extant P. nudiceps (west of the Suzuka Mountains),
fossil specimens have also been found in the Ise Bay area (Tsu), where P. ichikawai is the
only extant bagrid, and further east (Inasa).
Based on evidence that the latter is not a
sister species of P. nudiceps, the distribution of the fossils indicates that the range of P.
nudiceps was restricted to west of the Suzuka Mts. during the Pleistocene or Holocene.
Key words.— Fossil; Pseudobagrus ikiensis sp. nov.; Siluriformes; Bagridae;
zoogeography.
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川浦川における希少種ネコギギの生息個体数と分布
渡辺勝敏・伊藤慎一朗
Abstract
The population size of the endangered bagrid, Pseudobagrus ichikawai,
in the Kawaura River and its tributary, the Tsuzuya River (Nagara River system), was
estimated by a combination of night-visual-census and mark-release-recapture methods in
1996. The fish were distributed in patches in reaches of 6 km (Kawaura R.) and 2 km
(Tsuzuya R.) out of 11 km surveyed.
Visual counts in all 235 pools in the surveyed area
and mark-release-recapture experiments in five selected pools indicated that a correction
factor of ca. 4.3 times was necessary for the former, a total of 1460±100 SE fish being
present in pools. The total population including that in riffles was estimated as being
less than twice that in the pools, with 40–50% of the total population constituting the
reproductive group.
The effective population size was likely to be less than this
proportion, owing to a sex ratio bias towards females.
Larger pools tended to be
occupied by greater numbers of fish, both the number and density of fish in a pool being
positively correlated with the number of fish in neighboring pools.
These results
suggested that movement between the pools is important for the persistence of the P.
ichikawai population, which is presently somewhat fragmented by many weirs on the
river.
キーワード：ギギ科，絶滅危惧種，保全，長良川水系，個体数推定
Fossil record of a silurid catfish from the Middle Miocene Sanuki Group
of Ohkawa, Kagawa Prefecture, Japan
Katsutoshi Watanabe, Teruya Uyeno & Shigeru Mori
7
Abstract
A fossil specimen identified as a silurid catfish (92.5 mm SL) was
collected from the Middle Miocene Sanuki Group (15.8±0.9 Ma) of Ohkawa, Kagawa
Prefecture, Japan.
This is the oldest certain record of a silurid catfish. Morphological
characteristics of the specimen are as follows: 52 or 53 vertebrae, 61 or 62 anal fin rays, a
stout, short spine (11 %SL) and 10 or more soft rays of the pectoral fin, 8 or more pelvic
fin rays, 8 or more branchiostegal rays, head length of ca. 24 %SL, and most probably
not forked caudal fin. The fossil specimen is clearly distinct from three extant silurids
in Japan, and probably belongs to an undescribed form considering its geological age.
Key words.—Siluriformes; Siluridae; fossil catfish; Miocene Sanuki Group
Parsimony analysis of the distribution pattern of Japanese primary
freshwater fishes, and its application to the distribution of the bagrid catfishes
Katsutoshi Watanabe
Abstract
The geographic distribution of Japanese primary and some secondary
freshwater fishes was analyzed using parsimony analysis of endemicity (PAE).
Analysis of 73 taxa (species and intraspecific forms) on the four main islands of Japan
(divided into 25 geographic areas), produced 44 most parsimonious cladograms. In all
of the latter, a total of eight single and compound areas were recognized as endemic areas
in nested relationships.
The area cladograms showed Japan as comprising a
middle-eastern Hokkaido area plus southern areas, the latter containing mainly a
northeastern-Honshu endemic area and more heterogeneous southwestern areas,
including four endemic areas (western Kyushu, southeastern Chugoku, middle Kinki and
Tokai around Ise Bay) and several peripheral areas.
Some
patterns, e.g., the
distinction in fauna across Fossa Magna, noted by previous studies, were supported by
these results.
Even though the analysis had some problems (e.g., not all geographic
8
ranges of taxa could be included), it provided evidence for the detection of general
distribution patterns, because the relationships or similarities among areas were clearly
defined by shared taxa. To demonstrate the historical implications of the analysis, the
allopatric distribution of four bagrid catfishes was reconsidered in the area cladogram.
The general pattern implied secondary extinction of Pseudobagrus nudiceps around Ise
Bay, which was in keeping with the fossil record.
Key words.— Biogeography; parsimony analysis of endemicity (PAE); endemic area;
Japanese freshwater fishes; Pseudobagrus.
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