This study examined 396 base pairs of the mitochondrial cytochrome b gene from 110 individuals belonging to the genus Hampala, a group of freshwater cyprinids that inhabit Southeast Asia. The samples were taken from various locations throughout Sarawak, Sabah, and peninsular Malaysia. The nucleotide sequences were subjected to phylogenetic analyses by using the neighbor-joining, maximum parsimony, and maximum likelihood methods. All three methods revealed the reciprocally monophyletic relationship of Hampala macrolepidota to the other Hampala forms, thus strongly supporting its status as a distinct species. Phylogenetic analysis also discovered the existence of two H. bimaculata lineages endemic to Borneo: (1) a newly identified species from the southern and central part of Sarawak assigned as H. bimaculata Type A and (2) the previously described H. bimaculata from northern Sarawak and the west coast of Sabah assigned as H. bimaculata Type B. However, the status of H. sabana and an intermediate form were not elucidated. The results suggest that the intermediate form from the Tawau population is actually a subpopulation of H. sabana, while the highly divergent intermediate form from Kalabakan could represent a cryptic species. The sharing of H. macrolepidota haplotypes in the southern peninsular Malaysia and southern and central Sarawak samples (Hm1 and Hm2) reflected the recent disconnection of the two regions, during the late Pleistocene. Overall, the partial sequence of the mitochondrial cytochrome b gene was useful for resolving the phylogenetic relationships among Hampala fishes in Malaysia.
A cryptic Bornean torrent frog of the genus Meristogenys, which is divergent genetically and morphologically from all known congeners, is described from mountain streams of western Sarawak, East Malaysia (Borneo). The species occurs sympatrically with the type species of the genus, M. jerboa, but apparently differs from it in adult coloration and larval morphology, such as keratodont formulae and glands in tail fins. Females of the new species possess much larger and fewer eggs than in sympatric M. jerboa, suggesting significantly different reproductive traits between these species. A key to larvae of known species of the genus is provided.
Two lineages of stream toads in the genus Ansonia from Malaysian Borneo have long been suspected to be specifically distinct on the basis of molecular data. We assessed the taxonomic status of these lineages using morphological and additional genetic data. In mtDNA phylogeny, each lineage-one from Bario, Kelabit Highlands of Sarawak, the other from Mt. Mulu of Sarawak and the Crocker Range of Sabah-is separated from other congeners by large genetic distances, comparable with those observed between heterospecific species in the genus. These lineages are also morphologically distinguishable from other species, and are considered to represent valid, independently evolving species. We therefore describe them as A. kelabitensis sp. nov. and A. kanak sp. nov.
A new small, semi-arboreal toad of the genus Pelophryne is described from western Sarawak, Malaysian Borneo, on the basis of molecular and morphological evidence. Of the two morphotypes recognized in the genus, the new species belongs to the one in which the tips of the fingers are expanded into truncate discs. Among the species in the morphotype, the new species is most similar to P. murudensis, but differs from it by body size, relative hindlimb length, and dorsal coloration. The new species is currently known only from a limited area on Gunung (= Mt.) Penrissen, and future measures of its habitat conservation are necessary.
We describe a new species of cascade frog of the genus Rana, from west Malaysia. Rana monjerai, new species is a medium-sized frog of the subgenus Odorrana (SVL of males, 38-43 mm; of one female, 75 mm), and is distinguished from all other members of this subgenus by the combination of: white lip stripe, dorsolateral fold, full web on the fourth toe, vomerine teeth, gular vocal pouch and relatively large tympanum in males, no dorsal marking, no clear light spots on rear of thigh, first finger subequal to second, finely tuberculated dorsum, and unpigmented ova. The significance of finding this species from peninsular Malaysia is discussed.
We establish a new interstitial polyclad species, Theama japonica sp. nov., based on specimens collected from coarse-sandy habitats in three Japanese main islands (Hokkaido, Honshu, and Shikoku) along the coasts of the Pacific Ocean and the Sea of Japan. Theama japonica is characterized by i) two pairs of cerebral eyespots and four to six precerebral eyespots; ii) eosinophilic secretion glands distributed in the distal half of the inner ventral part of the prostatic vesicle; iii) a conical penis papilla, bent up dorsally, with a sclerotized inner wall; iv) the prostatic sheath with an inner angular fold on the dorso-distal side; and v) the external cilia longer dorsally than ventrally. Partial sequences of the cytochrome c oxidase subunit I (COI) gene from 20 specimens collected at eight localities along Japanese coasts represented 19 haplotypes. The uncorrected p-distances among these COI haplotypes fell within intraspecific variations observed in other polyclads. A network analysis based on these COI haplotypes suggested a geographically non-cohesive genetic structure of the species, possibly indicating the species' high dispersibility. Molecular phylogenetic analyses based on a concatenated dataset of 18S and 28S rDNA sequences showed T. japonica formed a clade with other Theama species. The resulting tree also indicates that our new species is more closely related to Theama sp. from Colombia than species from Panama and Croatia.
Bats play crucial ecological and economic roles. However, this group of mammals is largely threatened due to anthropogenic activities inside or around their caves. In the present study, we investigate the effects of cave microclimate and physiological parameters on bat roost preference in Fairy Cave Nature Reserve (Fairy Cave NR). The microclimate and physiological parameters including temperature (°C), relative humidity (RH), light intensity (lux), air flow, passage dimension (m), roost height (m) and distance of roost from nearest entrance (m) were measured. Results showed that Emballonura monticola, Hipposideros diadema, Hipposideros larvatus and Penthetor lucasi roost in Fairy Cave NR. These bats can be distinguished by their colony size, roost posture, spatial arrangement and position of their roost. Penthetor lucasi makes up the largest colony in the bright zone, whereas E. monticola has the smallest colony, occupying the twilight zone throughout the cave. Members from the family Hipposideridae roost in the dark portion of the cave with zero light intensity. Emballonura monticola utilizes the hottest roost in the cave compared to the other microbats, whereas H. diadema inhabits the coolest roost. Physiological parameters such as light intensity, passage dimension, and distance from nearest entrance are significant parameters in roosting preferences. These parameters should be monitored to ensure the sustainability of not only the aforementioned species, but also other species that roost in nearby caves of Bau limestone (Wind Cave Nature Reserve: with 13 recorded species).
We surveyed natural population of the Drosophila ananassae species complex on Penang Island, Malaysia. Analyses of phenotypic traits, chromosome arrangements, molecular markers, and reproductive isolation suggest the existence of two species: D. ananassae and D. cf. parapallidosa. Molecular marker analysis indicates that D. cf. parapallidosa carries chromosome Y and 4 introgressions from D. ananassae. Thus, D. cf. parapallidosa seems to be a hybrid descendant that recently originated from a natural D. parapallidosa♀× D. ananassae♂ cross. Furthermore, D. cf. parapallidosa behaves differently from authentic D. parapallidosa with respect to its reproductive isolation from D. ananassae. Premating isolation is usually seen in only the D. ananassae♀× D. parapallidosa♂ cross, but we observed it in crosses of both directions between D. ananassae and D. cf. parapallidosa. In addition, hybrid males from the D. ananassae♀× D. parapallidosa♂ cross are usually sterile, but they were fertile when D. ananassae♀ were mated with D. cf. parapallidosa ♂. We attempted an artificial reconstruction of the hybrid species to simulate the evolutionary process(es) that produced D. cf. parapallidosa. This is a rare case of natural hybrid population in Drosophila and may be a useful system for elucidating speciation with gene flow.
A new microhylid, Kalophrynus yongi, Is described from the Cameron Highlands of Peninsular Malaysia. Morphologically, the new species differs from all known congeners by having a very stout forelimb with a humeral spine in males. Acoustically, it resembles K. baluensis and K. heterochirus and sharply differs from K. interlineatus, K. pleurostigma, K. palmatissimus, and K. nubicola.
A new species in the rhacophorid genus Philautus is described on the basis of five male specimens collected from the Matang Range, a herpetologically well-surveyed area of the lowland of Sarawak, western Borneo. The species possesses a cutaneous pectoris muscle but lacks vomerine teeth, and is assigned to the aurifasciatus group of Philautus. It is superficially similar to some other species of the same group, but can be differentiated from them by a combination of several morphological characters, including lack of a nuptial pad and lingual papilla, and more significantly, by a distinct advertisement call. This discovery underscores the immediate necessity for detailed surveys in the already well-explored lowlands of Borneo.
Three new megophryid species, Leptolalax melanoleucus, L. fuliginosus, and L. solus, are described from southwestern and southern Thailand on the bases of acoustic and morphological characteristics. Leptolalax melanoleucus and L. fuliginosus are similar to L. pelodytoides from northern Thailand, but differ from it completely in advertisement call characteristics and ventral color. Leptolalax solus is similar to L. heteropus from peninsular Malaysia, but differs from it by advertisement call, as well as by some body proportions. The distributional pattern of Leptolalax within Thailand is discussed.
A new fish leech, Branchellion brevicaudatae sp. n., is described based on specimens parasitizing the gills of the short-tail stingray, Bathytoshia brevicaudata (Hutton, 1875), collected from Japanese waters. The new species can be distinguished from other congeners by having: i) pulsating vesicles emerging from posterior base of branchiae, one pair per somite; ii) dorsal white spots, not arranged in longitudinal row; and iii) blackish body. A phylogenetic tree based on partial sequences of the mitochondrial cytochrome c oxidase subunit I gene from the new species and other piscicolid worms showed that the new species is sister to Branchellion torpedinis Savigny, 1822. This is the first record of Branchellion Savigny, 1822 from Japanese waters.
A new megophryid species is described from southwestern Sarawak, Malaysian Borneo. In appearance, Leptolalax marmoratus sp. nov. is most similar to L. hamidi also from southwestern Sarawak, but differs from it by mtDNA sequence, larger body size, and higher dominant frequency of advertisement call. The assumption that more than one species of Leptolalax coexist at one locality in Borneo is supported. The finding of the new species raises the species number of Leptolalax known from Borneo to nine, and the island is thought to be one of the diversification centers of the genus.
The red-bellied form of Calliophis intestinalis (Laurenti, 1768) sensu lato was originally reported from Pahang, west Malaysia. To determine the taxonomic status of this form, we examined the type specimens of Elaps sumatranus Lidth De Jeude, 1890, Calliophis intestinalis everetti (Boulenger, 1896), and Callophis furcatus var. nigrotaeniatus Peters, 1863. The results indicated that the red-bellied form of C. intestinalis should be named as Calliophis nigrotaeniatus comb. nov., whose valid species status was based on morphological and molecular analyses. We designate a lectotype and redescribe the species, which is genetically close to Calliophis bilineatus (Peters, 1881) from the Philippines, and is clearly distinguishable from other congeners by possessing a pair of gray or dark blue lateral stripes and by being bright red on the ventrum. Elaps sumatranus and C. i. everetti are relegated to subjective junior synonyms of C. nigrotaeniatus.
Rats (Rattus species) are the most notorious vertebrate pests in Malaysian oil palm plantations. Although many studies have been conducted on Asian rats, little attention has been paid to their species composition and phylogenetic relationships in oil palm plantations in Peninsular Malaysia. We determined the mitochondrial cytochrome oxidase subunit I (COI) gene sequence (708 bp) for 216 individual rats collected from five oil palm plantations in Peninsular Malaysia. Phylogenetic analysis in conjunction with comparison with sequences from the nucleotide sequence database revealed five distinct lineages in the Malaysian oil plantations: Rattus tiomanicus, Rattus argentiventer, Rattus exulans, Rattus tanezumi, and a taxon corresponding to the Malayan house rat, which was most frequently observed (∼50%). The last taxon has traditionally been classified as a synonym of Rattus rattus (Rattus rattus diardii) or Rattus tanezumi, but our phylogenetic analysis placed it as an independent lineage, which is not particularly closely related to R. rattus or R. tanezumi, and which we refer to as Rattus diardii. The construction of the network showed that there is considerable genetic variation within the lineages of R. diardii and R tiomanicus, suggesting that these two species are native to the Malay Peninsula.
We examined allozyme variation in two camaenid tree snails, Amphidromus atricallosus and A. inversus, across two principal regions of Thailand and from Singapore, plus for A. inversus, one site in peninsular Malaysia. Using horizontal starch gel electrophoresis, 13 allozyme loci (11 polymorphic) were screened for A. atricallosus and 18 (5 polymorphic) for A. inversus. Heterozygosity was higher in A. atricallosus (Hexp=0.018-0.201, mean=0.085) than in A. inversus (Hexp=0-0.023, mean= 0.002). Genetic heterogeneity among samples was higher in A. inversus (Fst=0.965) than in A. atricallosus (Fst=0.781). Within A. atricallosus, populations were more differentiated in southern Thailand (Fst=0.551) than in eastern Thailand (Fst=0.144). The high Fst and low Hexp in populations of A. inversus suggest that this species is likely to have experienced a series of strong bottlenecks, perhaps occurring chiefly on offshore continental-shelf islands. The low Fst values of A. atricallosus in eastern Thailand suggest frequent gene flows among populations in this region. The southern and eastern samples of A. atricallosus exhibited fixed allele differences at four loci and great genetic distance (Nei's D=0.485-0.946), suggesting that these two samples may actually represent, or else be evolving into, separate species.
The two-pore domain potassium ion (K + ) channel-related K + (TREK) channel and melatonin receptors play roles in the regulation of reproduction in zebrafish. Since reproduction is regulated by diurnal rhythms, the TREK family and melatonin receptors may exhibit diurnal rhythms in expression. In this study, we aimed to investigate diurnal variations of the gene expressions of TREK family and melatonin receptors and their associations with kisspeptin and gonadotrophin-releasing hormone (GnRH). Diurnal variations of trek1b, trek2a, trek2b, mt1, mt2, mel1a, kiss2 and gnrh3 expressions were examined by real-time PCR. For reproduction-related genes, kiss2 and gnrh3 exhibited diurnal rhythms. trek2a revealed a diurnal rhythm in the TREK family. mt2 and mel1c exhibited diurnal rhythms in the melatonin receptors. Since Trek2a regulates gnrh3 expression, the diurnal rhythm of gnrh3 expression suggests to be regulated by the diurnal rhythm of trek2a expression.
Mesohabitat selection in fluvial fishes was studied in a small tropical stream of the Malay Peninsula. A total of 681 individuals representing 24 species were sampled at 45 stations within heterogeneous stream (ca. 1 km in length), in which water depth, water velocity, substrate size, and riparian canopy cover were measured as environmental variables. A canonical correspondence analysis (CCA) yielded a diagram that shows a specific mesohabitat selection of the fish assemblage, in which the species were plotted widely on the CCA1-CCA2 biplot. Generalized linear model also revealed a significant pattern of the mesohabitat selection of several species. Water velocity and substrate size mainly separated on CCA1, indicating variation of pool (deep, slow-flow section) and riffle (shallow, fast-flow section) structures is a primary factor of mesohabitat selection in the fluvial fish assemblage. The mean body weight of species significantly correlated with CCA1; larger species tended to inhabit pools, while small ones occupied riffles. The riparian canopy cover separated on CCA2. The trophic level of species significantly correlated with CCA2; herbivorous species (low trophic level) selected open sites without riparian cover, whereas omnivorous/carnivorous (middle-high trophic level) species preferred highly covered sites. In conclusion, our results suggest that mesohabitat selection is closely related to the species feeding habit, which is consistent with the results of previous studies.
In general, African catfish shows higher survival rates in the dark conditions than in the light conditions. In this study, larval behavior of African catfish was observed under 0, 0.01, 0.1, 1, 10, and 100 lx using a CCD camera to investigate the reason why African catfish larvae show higher survival rates in dark conditions. The larvae showed significantly higher swimming activity under 0, 0.01, and 0.1 lx than that under 10 and 100 lx. The larvae also showed significantly increased aggressive behavior under 10 and 100 lx; the swimming larvae attacked resting individuals more frequently under 10 and 100 lx than under 0, 0.01, and 0.1 lx. The aggressive behavior and sharp teeth of the attacking larvae appeared to induce skin surface lesions on injured larvae. Chemical substances were then generated from the injured skin surface, and these chemical stimuli triggered cannibalistic behavior in other fish near the injured fish. The results of this study demonstrate that the higher survival rates of African catfish larvae under dark conditions are a result of inactivity and subsequent increase in chemical releasing stimuli concentrations around inactive individuals that triggers feeding behavior in nearby active catfish. Therefore, we recommend larval rearing of African catfish in dark or dim conditions, as it improves catfish survival rates.
This study was conducted to clarify the development of free neuromasts with growth of the barramundi, Lates calcarifer. A pair of free neuromasts was observed behind the unpigmented eyes in newly hatched eleutheroembryos with a mean total length of 1.93 mm, and two-hour-old eleuthero-embryos could respond to an approaching pipette. At 2 days after hatching, the egg yolk sac was mostly consumed, the eyes were pigmented, and the larvae commenced feeding on rotifers. Free neuromasts increased in number with growth and commenced developing into canal neuromasts in barramundi 15 days old with a mean total length of 8.07 mm. The average length of the major axis of the trunk free neuromasts attained approximately 12.9-15.5 microm, and the number of sensory cells was 15.4-17.5 at 15-20 days old. Developed cupulae of free neuromasts were observed in 1-day-old eleutheroembryos. The direction of maximum sensitivity of free neuromasts, determined from the polarity of the sensory cells, coincided with the minor axis of the lozenge-shaped outline of the apical surface of the free neuromasts. The polarity of trunk neuromasts was usually oriented along the antero-posterior axis of the fish body, but a few had a dorso-ventral direction. On the head, free neuromasts were oriented on lines tangential to concentric circles around the eye.