example of (rather convoluted) way to parse prefixed tag names using etree

ns.py

from StringIO import StringIO
import xml.etree.ElementTree as ET

mvco_ns = 'http://ifcb-data.whoi.edu/mvco/'
lid = 'IFCB5_2011_033_041857'
nsmap = {'mvco': mvco_ns}

def parse_id(pfx_id, nsmap={}):
    ns_statements = ' '.join(['xmlns:%s="%s"' % (k,v) for k,v in nsmap.items()])
    xml = '<%s %s/>' % (pfx_id, ns_statements)
    return ET.parse(StringIO(xml)).getroot().tag

print parse_id('mvco:%s' % lid, nsmap)