(Crain’s) — A scrap broke out last week in the online marketplace aimed at African-Americans, spurred by the latest audience numbers from comScore. Moguldom Media Group, a feisty indie based in the city, declared that it was now the No. 1 network of owned and operated sites targeting the black audience. Not so fast, responded Interactive One, the New York-based digital arm of Radio One, which insists that by any count it’s the biggest. ComScore, in fact, shows that traffic on the company’s sites, including those for some 50 radio stations, totaled 4.3 million unique visitors in May. That compares to 2.6 million for Moguldom, whose executives argue that radio station sites belong in a different category, as does Interactive One’s social-networking site, BlackPlanet. The jockeying for leadership is characteristic of the black online-media segment, which has been growing so fast it can be hard to keep track of the front-runners. The challenge now is persuading advertisers to step up investment in these targeted sites instead of favoring the bigger, general-market properties on the Web that attract audiences of all ethnicities.