NOVELTY - Isolated glycoside hydrolase (GH)61 polypeptide consisting of: a GH61 polypeptide comprising an amino acid sequence having at least 95% sequence identity to amino acids 19-349 of SEQ ID NO: 4 (comprising fully defined 349 amino acids as given in the specification); or a GH61 polypeptide encoded by a polynucleotide comprising a nucleotide sequence having at least 95% sequence identity to nucleotides 55-1099 of SEQ ID NO: 3 (comprising fully defined 1102 nucleotides as given in the specification) or its cDNA sequence, is new.    USE - The isolated GH61 polypeptide is useful: to produce a transgenic plant, plant part or plant cell, a protein and a fermentation product; for degrading or converting a cellulosic material and fermenting a cellulosic material (all claimed); and in a detergent composition.    ADVANTAGE - The isolated GH61 polypeptide exhibits cellulolytic enhancing activity.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for: (1) a nucleic acid construct comprising the isolated polynucleotide sequence that encodes the GH61 polypeptide operably linked to at least one heterologous control sequence that directs production of the polypeptide in an expression host; (2) a recombinant expression vector comprising an isolated polynucleotide comprising a nucleotide sequence that encodes the GH61 polypeptide; (3) an isolated recombinant host cell comprising an isolated polynucleotide comprising a nucleotide sequence that encodes the GH61 polypeptide; (4) producing the GH61 polypeptide; (5) producing a mutant of an isolated Thermoascus crustaceus parent cell, comprising disrupting or deleting a polynucleotide encoding the GH61 polypeptide or its portion in the isolated Thermoascus crustaceus parent cell, which results in the mutant producing less of the polypeptide than the parent cell; (6) a transgenic plant, plant part or plant cell transformed with a polynucleotide encoding the GH61 polypeptide, where the polypeptide comprises a signal peptide directing the polypeptide into the secretory pathway; (7) an isolated polynucleotide encoding a signal peptide comprising or consisting of amino acids 1-18 of SEQ ID NO: 4; (8) producing a protein, comprising cultivating a recombinant host cell comprising a gene encoding the protein operably linked to an isolated polynucleotide encoding the signal peptide comprising or consisting of amino acids 1-18 of SEQ ID NO: 4, where the gene is foreign to the polynucleotide encoding the signal peptide, under conditions conducive for production of the protein and recovering the protein; (9) degrading or converting a cellulosic material, comprising treating the cellulosic material with an enzyme composition in the presence of the GH61 polypeptide having cellulolytic enhancing activity; (10) producing a fermentation product, comprising saccharifying a cellulosic material with an enzyme composition in the presence of the GH61 polypeptide, fermenting the saccharified cellulosic material with at least one fermenting microorganism to produce the fermentation product and recovering the fermentation product from the fermentation; and (11) fermenting a cellulosic material, comprising fermenting the cellulosic material with at least one fermenting microorganisms, where the cellulosic material is saccharified with an enzyme composition in the presence of the GH61 polypeptide.