diff --git a/src/ecoisundertaxon.c b/src/ecoisundertaxon.c
new file mode 100644
index 0000000..f850efc
--- /dev/null
+++ b/src/ecoisundertaxon.c
@@ -0,0 +1,41 @@
+#include "libecoPCR/ecoPCR.h"
+#include <string.h>
+#include <stdlib.h>
+#include <getopt.h>
+#include <stdio.h>
+
+
+int main(int argc, char **argv){
+	int32_t     	carg 		= 0;
+	int32_t			taxid_1		= 0;
+	int32_t			taxid_2		= 0;
+	ecotaxonomy_t 	*taxonomy	= NULL;
+	ecotx_t			*son		= NULL;	
+	
+	while ((carg = getopt(argc, argv, "1:2:")) != -1) {
+	    switch (carg) {                              
+	        case '1':
+	           sscanf(optarg,"%d",&taxid_1);
+	           break;
+	
+	        case '2':     
+	           sscanf(optarg,"%d",&taxid_2);
+	           break;
+	     }
+	}
+		
+	taxonomy = read_taxonomy(argv[optind]);
+	
+	son = eco_findtaxonbytaxid(taxonomy, taxid_2);
+
+	//printf("# %s\n",son->parent->name);
+	
+	/*	
+	if (eco_isundertaxon(son, tax_id_2))
+		printf("tax_id_1 is son of tax_id_2");
+	else
+		printf("tax_id_1 is NOT son of tax_id_2");
+	*/
+	
+	return 0;
+}
\ No newline at end of file