Here is the 2015 BJCP description which a dunkleweisse is judged against.
Impression
A moderately dark German wheat beer with a distinctive banana-and-clove yeast character, supported by a toasted bread or caramel malt flavor. Highly carbonated and refreshing, with a creamy, fluffy texture and light finish that encourages drinking.
Aroma
Moderate phenols (usually clove) and fruity esters (usually banana). The balance and intensity of the phenol and ester components can vary but the best examples are reasonably balanced. Optionally, a low to moderate vanilla character and/or faint bubblegum notes may be present, but should not dominate. Hop aroma ranges from low to none, and may be lightly floral, spicy, or herbal. A light to moderate wheat aroma (which might be perceived as bready, doughy or grainy) may be present and is often accompanied by a caramel, bread crust, or richer malt aroma. The malt aroma may moderate the phenols and esters somewhat.
Appearance
Light copper to mahogany brown in color. A very thick, moussy, long-lasting off-white head is characteristic. The high protein content of wheat impairs clarity in this traditionally unfiltered style, although the level of haze is somewhat variable. Suspended yeast sediment can contribute to cloudiness.
Flavor
Low to moderately strong banana and clove flavor. The balance and intensity of the phenol and ester components can vary but the best examples are reasonably balanced and fairly prominent. Optionally, a very light to moderate vanilla character and/or faint bubblegum notes can accentuate the banana flavor, sweetness and roundness; neither should be dominant if present. The soft, somewhat bready, doughy, or grainy flavor of wheat is complementary, as is a richer caramel, toast, or bread crust flavor. The malty richness can be low to medium-high, and supports the yeast character. A roasted malt character is inappropriate. A spicy, herbal, or floral hop flavor is very low to none, and hop bitterness is very low to low. Well-rounded, flavorful, often somewhat malty palate with a relatively dry finish.
Mouthfeel
Medium-light to medium-full body. The texture of wheat as well as yeast in suspension imparts the sensation of a fluffy, creamy fullness that may progress to a lighter finish, aided by moderate to high carbonation. Effervescent.
Comments
The presence of Munich and/or Vienna-type barley malts gives this style a deep, rich barley malt character not found in a weissbier. Often known as Dunkelweizen , particularly in the United States.
History
Bavaria has a wheat beer brewing traditional hundreds of years old, but the brewing right was reserved for Bavarian royalty until the late 1700s. Old-fashioned Bavarian wheat beer was often dark, as were most beer of the day. Pale weissbier started to become popular in the 1960s, but traditional dark wheat beer remained somewhat of an old person’s drink.
Ingredients
By German brewing tradition, at least 50% of the grist must be malted wheat, although some versions use up to 70%; the remainder is usually Munich, Vienna, or dark or caramel wheat malts, or Pilsner malt with color malt. A decoction mash is traditional, but infrequently used today. Weizen ale yeasts produce the typical spicy and fruity character, although extreme fermentation temperatures can affect the balance and produce off-flavors.
Comparison
Reflecting the best yeast and wheat character of a weissbier blended with the malty richness of a Munich dunkel. The banana and clove character is often less apparent than in a weissbier due to the increased maltiness.
Examples
Ayinger Ur-Weisse, Ettaler Weissbier Dunkel, Franziskaner Hefe-Weisse Dunkel, Hacker-Pschorr Weisse Dark, Tucher Dunkles Hefe Weizen, Weihenstephaner Hefeweissbier Dunkel
Vital Statistics
IBUs: 10 - 18
OG: 1.044 - 1.056
ABV: 4.3 - 5.6
FG: 1.010 - 1.014