Spells per Day

At the indicated levels, a dragon disciple gains new spells per day as if he had also gained a level in an arcane spellcasting class he belonged to before adding the prestige class. He does not, however, gain other benefits a character of that class would have gained, except for additional spells per day, spells known (if he is a spontaneous spellcaster), and an increased effective level of spellcasting. If a character had more than one arcane spellcasting class before becoming a dragon disciple, he must decide to which class he adds the new level for purposes of determining spells per day.