term for a brand run by a company without direct acknowledgment?

The classic example of this in my mind is the relationship between Lexus and Toyota. At least in the United States, Lexus is not presented as "Lexus... by Toyota". From a newcomer's perspective, it is a fully independent entity.

For Toyota, Lexus was targeted at a specific market segment, sales to which might have been adversely impacted by using the Toyota name.

The term I thought of for this was "house brand", but googling suggests that term's meaning is generally confined to supermarket generics like "Sam's Choice".

Can someone please help me properly name this brand relationship?

Wikipedia's article on brand architecture suggests the term individual product brand for such cases:

Individual branding, also called individual product branding or multibranding, is the marketing strategy of giving each product in a portfolio its own unique brand name. This contrasts with family branding, corporate branding, and umbrella branding in which the products in a product line are given a single overarching brand name. The advantage of individual branding is that each product has an image and identity that is unique. This facilitates the positioning of each product, by allowing a firm to position its brands differently.

In the motor trade this method of branding is usually called a marque. Presumably motor vehicles are expensive enough to justify a hifalutin' synonym for brand.