ABSTRACT
A new species of small freshwater prawn in the Macrobrachium pilimanus species group was found in the upper southern peninsula of Thailand. The prawns in this group exhibit velvet setae on the telopodites of the second pereiopods. The new species, named M. prachuapense sp. nov., is endemic to Thailand. It has several characteristics that make it standing apart and different from closely related species in the group, e.g. M. naiyanetri, M. forcipatum, M. malayanum, M. dienbienphuense, M. eriocheirum, and M. pilosum. The distinguishing characteristic of the new species is the shape of carpus of the second pereiopod (sub-cylindrical and subequal to palm), similar only to that of M. dienbienphuense. However, a fully-grown male of the new species was less than two-third the size of a fully-grown male M. dienbienphuense. Phylogenetic analysis further enhanced its novel species status with respect to its position in the phylogenetic tree relative to other closely related species.
Subject(s)
Palaemonidae/classification , Animals , Body Size , Fresh Water , Male , Phylogeny , ThailandABSTRACT
A small wild prawn of the genus Macrobrachium, found in Chiang Rai Province, Northern Thailand has some morphological features resembling four other closely related species, M. lanchesteri, M. peguense, M. kunjuramani, and M. chainatense. However, it is distinguishable from the above species in terms of distinctive golden colored antennules; number of teeth on the rostrum; number of teeth on the cutting edges of the second pereiopod; and length of carpus relative to that of chela on the second pereiopod. Moreover, DNA analysis places it far apart on the phylogenetic tree from the related species in the genus.
Subject(s)
Decapoda , Palaemonidae , Animals , Phylogeny , ThailandABSTRACT
Many species of freshwater prawns, large and small, inhabit Southeast Asian countries. In Thailand alone, there have been recent reports of new species in the genus Macrobrachium. Morphological differentiation and, recently, DNA sequence differences have been used to distinguish new species from valid ones. Macrobrachium chainatense (Decapoda: Palaemonidae), a small freshwater prawn found in Thailand, is now established as a new species based on both morphological and genetic criteria. Among Thailand Macrobrachium prawns, M. chainatense has smallest body size, largest egg size, and 3-5 teeth on the cutting edges. The most closely related Macrobrachium species to M. chainatense in terms of COI and 18S DNA sequences is M. niphanae. Their COI sequences differ by 7.3% while their 18S sequences are basically identical in all but one site. Observations of some aspects of this prawn in captivity are also utilized to establish its unique species status. This prawn may be useful as a source of cooked food for human consumption.
Subject(s)
Palaemonidae , Animals , Fresh Water , Humans , Phylogeny , ThailandABSTRACT
A new species of Moina Baird, 1850 (Cladocera: Moinidae) is described based on material collected from Thailand (South-East Asia). In tropical Asia, Moina siamensis sp. nov. could be confused easily with M. weismanni Ishikawa, 1896, because of morphological similarities in parthenogenetic females and males of both species. The outstanding difference between these two taxa concerns the structure of the ephippium in gamogenetic females, which is highly visible under light and scanning electron microscopes. The mature ephippium of M. weismanni is strongly tuberous, with distinct borders between cells, whereas the ephippium of M. siamensis sp. nov. is significantly less tuberous, with prominent longitudinal lines in its central region. Since gamogenetic females only appear sporadically in moinid populations, distribution ranges of M. siamensis sp. nov., M. weismanni and sibling taxa must be clarified precisely using genetic markers in the future. Preliminary investigations of the ephippium structure may be useful for estimating the differences between populations, thus revealing much diversity within Moinidae.
Subject(s)
Cladocera , Animals , Female , Male , Parthenogenesis , Reproduction , ThailandABSTRACT
A small freshwater prawn in Thailand has been found to be a new species and is named Macrobrachium suphanense (Decapoda: Palaemonidae). Fully grown male M. suphanense appeared very different from the most closely related male of M. sintangense: size smaller, second pereiopod smaller and less robust, rostrum form different and, in females, fewer eggs. Less closely related, fully grown M. dolatum has sharper distal cutting edge on fixed finger and M. hungi has longer rostrum than M. suphanense. DNA analyses put M. suphanense, M. sintangense and M. nipponense in the same clade with M. nipponense sister to the other two. Two more clades consist of M. dienbienphuense and M. niphanae on the one hand and M. lanchesteri and M. rosenbergii on the other. The relationship among the three clades is not clearly resolved.
