This new subgenus is erected for 12 (or more) species that given the present data form a monophyletic group which is endemic to Australia.

Diagnosis.

Males: Body length 9.9-11 mm; mandible with tree teeth; ventral margin of mandible with basal projection; hypostomal area modified with rounded excavation, in some species with tooth on inner rim; Fore tarsus modified; Ta1 short, less than 2x as long as wide, one or more tarsomeres flattened or expanded, often with smooth areas or dark spots on ventral surface (also in some other subgenera); Ta1 of fore tarsus with anterior margin extended forming a longitudinal groove or flat area bordered by a row of hairs or setae; fore coxa flat, with large tooth like lobe at inner posterior corner, posterior half with stiff orange setae (which is unique for this group), anterior half bare, outer area with long white pubescence; T6 carina bidentate; the genital morphology of this group is characterized by complex gonostyli with large hindward directed medio-inner lobes, patches of strong setae, and with apices divided in two lobes, the outer lobe with long setae. The shape of these lobes, and the length and direction of setae vary among species.

Females: Body length 9.8-12.5 mm. There are no autapomorphic or diagnostic characters for the females of the species in this group. There are a few robust species (11.5-12.5 mm) with a large patch of orange pubescence on T6 (i.e. M. chrysopyga, M. maculariformis, and M. chrysopygopsis), most other species in this group are smaller with variable extend and colour of pubescence on T6.

Etymology: The name Notochile is a combination of ‘noto’ meaning ‘south’ or ‘southern’ and ‘chile’ which is part of the genus name Megachile indicating the southern distribution, i.e. Australia, for the species in this clade.