Table 1. Inter-River-System (IRS) model according to Craul et al. (2007) and corresponding Lepilemur species as assigned in previous studies (Andriaholinirina et al., 2006; Craul et al., 2007; Lei et al., 2017; Louis et al., 2006; Rabarivola et al., 2006; Zinner et al., 2007) .

IRS	River	Andriaholinirina et al. (2006)	Louis et al. (2006)	Rabarivola et al. (2006)	Craul et al. (2007)	Zinner et al. (2007)	Lei et al. (2017)	This study
*: Nosy Bé is here regarded as a part of IRS VI (see Andriaholinirina et al., 2006 and Craul et al., 2007).
0	Mahavavy –Besiboka	aeeclis	aeeclis	aeeclis	aeeclis	aeeclis	aeeclis	aeeclis
I	Besiboka – Mahajamba	edwardsi	edwardsi	edwardsi	edwardsi	edwardsi	edwardsi	edwardsi
II	Mahajamba – Sofia	No samples	No samples	No samples	otto	otto	otto	otto
III	Sofia – Maevarano	No samples	grewcockorum	No samples	manasamody	grewcockorum	grewcockorum	grewcockorum
IV	Maevarano – Andranomalaza	sahamalaza	sahamalaza	sahamalaza	sahamalaza	sahamalaza	sahamalaza	sahamalaza
V	Andranomalaza – Sambirano	No sample	dorsalis	mittermeieri	dorsalis	mittermeieri	dorsalis	dorsalis
VI	Sambirano – Mahavy	dorsalis	No samples	dorsalis	dorsalis	tymerlachsoni	No samples	tymerlachsoni
VI*	Nosy Bé	dorsalis	tymerlachsoni	dorsalis	dorsalis	tymerlachsoni	tymerlachsoni	tymerlachsoni
VII	North of Mahavy	ankaranensis	ankaranensis	ankaranensis	ankaranensis	ankaranensis	ankaranensis	ankaranensis