KARAKTERISASI MORFOLOGI DAN MOLEKULER KERANG AIR TAWAR (BIVALVIA: UNIONIDAE) DARI SUNGAI BENGAWAN SOLO, INDONESIA

MORPHOLOGY AND MOLECULAR CHARACTERIZATION OF FRESHWATER MUSSELS (BIVALVIA: UNIONIDAE) FROM THE BENGAWAN SOLO RIVER, INDONESIA

Famili Unionidae merupakan famili kerang air tawar yang terbesar dan paling tersebar luas. Kerang air tawar Famili Unionidae memiliki banyak variasi morfologi, variasi yang tinggi seringkali menyebabkan kesalahan dalam identifikasi morfologi, sehingga diperlukan identifikasi secara molekuler. Kajian secara molekuler diperlukan untuk keakuratan identifikasi suatu spesies dan mendukung hasil identifikasi secara morfologi. Penelitian ini bertujuan untuk mendeskripsikan karakter morfologi dan molekuler kerang air tawar Famili Unionidae dari Sungai Bengawan Solo, Indonesia berdasarkan gen Cytochrome C Oxidase subunit I (COI). Metode penelitian meliputi pengambilan sampel, identifikasi sampel secara morfologi, isolasi DNA, amplifikasi gen COI dengan PCR, elektroforesis dan sekuensing. Karakterisasi morfologi dilakukan dengan pengamatan kualitatif dan kuantitatif. Hasil sekuensing dianalisis dengan software bioinformatika. Identifikasi morfologi menunjukkan bahwa di Sungai Bengawan Solo terdapat dua spesies kerang air tawar yaitu Rectidens sumatrensis dan Pilsbryoconcha exilis yang terdiri atas 2 variasi. Hasil karakterisasi molekuler menunjukkan bahwa nilai similaritas sampel penelitian Rectidens sumatrensis didapatkan hasil sebesar 96,46-96,99%, sedangkan  Pilsbryoconcha exilis sebesar 98,68-100%. Komposisi basa nukleotida G+C rata-rata sebesar 41,41%, sedangkan rata-rata komposisi basa nukleotida A+T sebesar 58,56%. Hasil identidikasi alignment seluruh sampel terdapat 10 variasi basa nukloetida yaitu pada basa nukleotida nomor 9, 68, 87, 174, 219, 240, 255, 279, 306, dan 375. Nilai rata-rata jarak genetik Rectidens sumatrensis sebesar 2,13%, Pilsbryoconcha exilis variasi 1 sebesar 0,87% dan Pilsbryoconcha exilis variasi 2 sebesar 0,86%. Hasil rekonstruksi pohon filogenetik dengan metode Neighbor Joining dan Maximum Likelihood adalah terbagi menjadi 3 cluster, cluster pertama terdiri atas sampel penelitian Pilsbryoconcha exilis dari Sungai Bengawan Solo dengan Pilsbryoconcha exilis asal Indonesia dan Malaysia dengan nilai bootstrap sebesar 100, cluster kedua terdiri atas sampel penelitian Rectidens sumatrensis asal Sungai Bengawan Solo dan Rectidens sumatrensis asal Malaysia dengan nilai bootstrap sebesar 100, dan cluster ketiga terdiri dari kelompok outgrup yaitu Corbicula javanica dengan nilai bootstrap sebesar 100. Dengan demikian, penelitian ini berhasil membuktikan bahwa terjadi suatu pemisahan secara jelas antara kedua spesies berdasarkan konstruksi pohon filogenetika dan keterkaitan antara karakterisasi morfologi dan molekular yang saling mendukung.

The Unionidae family is the largest and most widespread family of freshwater mussels. Freshwater mussels of the Unionidae family have many morphological variations, high variation often causes errors in morphological identification, so molecular identification is needed. Molecular studies are needed for the accuracy of species identification and support the results of morphological identification. This study aims to describe the morphological and molecular characters of freshwater mussels Family Unionidae from Bengawan Solo River, Indonesia based on the Cytochrome C Oxidase subunit I (COI) gene. The research methods included sampling, morphological sample identification, DNA isolation, COI gene amplification by PCR, electrophoresis and sequencing. Morphological characterization was carried out by qualitative and quantitative observations. Sequencing results were analyzed with bioinformatics software. Morphological identification showed that there were two species of freshwater mussels in the Bengawan Solo River, namely Rectidens sumatrensis and Pilsbryoconcha exilis, which consisted of 2 variations. The results of molecular characterization showed that the similarity value of the research sample Rectidens sumatrensis obtained results of 96.46-96.99%, while Pilsbryoconcha exilis was 98.68-100%. The average G + C nucleotide base composition is 41.41%, while the average A + T nucleotide base composition is 58.56%. The results of alignment identification of all samples contained 10 variations of nucleotide bases, namely nucleotide bases number 9, 68, 87, 174, 219, 240, 255, 279, 306, and 375. The average genetic distance value of Rectidens sumatrensis is 2.13%, Pilsbryoconcha exilis variation 1 is 0.87% and Pilsbryoconcha exilis variation 2 is 0.86%. The results of phylogenetic tree reconstruction using Neighbor Joining and Maximum Likelihood methods are divided into 3 clusters, the first cluster consists of research samples of Pilsbryoconcha exilis from Bengawan Solo River with Pilsbryoconcha exilis from Indonesia and Malaysia with a bootstrap value of 99, the second cluster consists of research samples of Rectidens sumatrensis from Bengawan Solo River and Rectidens sumatrensis from Malaysia with a bootstrap value of 100, and the third cluster consists of an outgroup group, namely Corbicula javanica with a bootstrap value of 100. Thus, this study successfully proves that there is a clear separation between the two species based on the construction of the phylogenetic tree and the correlation between morphological and molecular characterization, which mutually support each other.