NOVELTY - An isolated polypeptide having endoglucanase activity is new.    USE - The protein, polynucleotide, composition and methods are useful for degrading or converting a cellulosic material and for producing a substance, e.g. alcohol, organic acid ketone, amino acid, or gas (claimed). The polypeptides and host cells are useful for producing monosaccharides, disaccharides, and polysaccharides as chemical or fermentation feedstocks from cellulosic biomass for the production of ethanol, plastics, other products or intermediates.    DETAILED DESCRIPTION - An isolated polypeptide having endoglucanase activity is selected from (a) a polypeptide comprising an amino acid sequence having at least 90% identity with the mature polypeptide of SEQ ID NO: 2 or at least 60% identity with the mature polypeptide of SEQ ID NO: 4, (b) a polypeptide which is encoded by a polynucleotide which hybridizes under at least high stringency conditions with (i) the mature polypeptide coding sequence of SEQ ID NO: 1, (ii) the cDNA sequence contained in the mature polypeptide coding sequence of SEQ JD NO: 1, or (iii) a complementary strand of (i) or (ii), or under at least medium stringency conditions with (i) the mature polypeptide coding sequence of SEQ ID NO: 3, (iii) the genomic DNA sequence comprising the mature polypeptide coding sequence of SEQ ID NO: 3, or (iii) a complementary strand of (i) or (ii), (c) a polypeptide which is encoded by a polynucleotide comprising a nucleotide sequence having at least 90% identity with the mature polypeptide coding sequence of SEQ D NO: 1 or 60% identity with the mature polypeptide coding sequence of SEQ ID NO: 3, or (d) a variant comprising a substitution, deletion, and/or insertion of one or more amino acids of the mature polypeptide of SEQ D NO: 2 or 4. INDEPENDENT CLAIMS are:    (1) an isolated polynucleotide comprising a nucleotide sequence which encodes the polypeptide;    (2) a nucleic acid construct comprising the polynucleotide operably linked to one or more control sequences that direct the production of the polypeptide in an expression host;    (3) a recombinant expression vector comprising the nucleic acid construct of (2);    (4) a recombinant host cell comprising the nucleic acid construct of (2);    (5) a method for producing the polypeptide;    (6) a method for producing a mutant of a parent cell by disrupting or deleting a nucleotide sequence encoding the polypeptide which results in the mutant producing less of the polypeptide than the parent cell;    (7) a mutant cell produced by the method of (6);    (8) a method for producing a polynucleotide;    (9) a mutant polynucleotide produced by the method of (8);    (10) a transgenic plant, plant part, or plant cell, which has been transformed with the polynucleotide encoding the polypeptide;    (11) a method of degrading or converting a cellulosic material;    (12) a method of producing a substance;    (13) a method of inhibiting expression of a polypeptide in a cell; and    (14) a double-stranded RNA (dsRNA) molecule for inhibiting expression of a polypeptide in a cell, where the dsRNA comprises a subsequence or portion of a polynucleotide encoding the mature polypeptide of SEQ ID NO: 2 or 4.