Section 1: Introduction
The family-level classification of Madagascar primate genera into five families follows the recommendations of Schwartz and Tattersall (1985), but we recognize the new genus Eulemur as representing all members of genus Lemur other than Lemur catta, according to Simons and Rumpler (1988). Species and subspecies-level taxonomy is based on Tattersall (1982) with the exception that the arrangement of Lepilemur follows Petter et al. (1977) in recognizing seven species. However, since the appearance of Tattersall's book (1982), the taxonomy has been modified to reflect subsequently described species and taxonomic revisions. The two new species of lemurs mentioned above, Hapalemur aureus (Meier et al., 1987) and Propithecus tattersalli (Simons, 1988), have appeared since Tattersall's (1982) book. Other changes include the rediscovery of Eulemur macaco flavifrons (Koenders et al., 1985), Propithecus diadema holomelas placed in synonymy of P. d. edwardsi (Tattersall, 1986) and partition of Phaner furcifer into four subspecies (Groves and Tattersall, 1991). We do not consider the information in Tattersall (1988) sufficient to lump Propithecus verreauxi coronatus into synonymy with P. v. deckeni given the contradictory information reported in Harcourt and Thornback (1990) and our own observations.
Several taxonomic questions merit further study, including whether or not Propithecus diadema holomelas and P. d. edwardsi are synonymous, whether P. verreauxi deckeni and P. v. coronatus are synonymous, whether currently recognized Varecia variegata variegata (fide Tattersall, 1982) consists of two or three distinct subspecies and whether there exist undescribed subspecies of Eulemur rubriventer and Microcebus rufus (Tattersall, 1982).
Based on available information, the following list of taxa has been assembled.
Table 1 Taxonomy of Madagascar Lemurs
Five Families of Madagascar Lemurs
Upper left: Daubentonidae - Aye-aye Daubentonia madagascariensis (David Haring)
Upper right: Cheirogaleidae - Fat-tailed dwarf lemur Cheirogaleus medius (David Haring)
Lower left: Lemuridae - Red-bellied lemur Eulemur rubriventer (Russell A. Mittermeier)
Lower right: Megaladapidae - Nosy Be sportive lemur Lepilemur dorsalis (Russell A. Mittermeier)
Center: Indriidae - Indri Indri indri (Russell A. Mittermeier)
In recognizing levels of threat to existing lemur populations and in assigning priority ratings for conservation action, this document revises criteria used in the Action Plans for African and Asian Primate Conservation (Oates, 1986; Eudey, 1987). Degree of Threat is viewed in terms of total population size, estimated to the nearest order of magnitude, and considers that lemur habitats throughout Madagascar are severely and equally threatened. A single adjustment has been made for taxonomic uniqueness; the highest priority is now set at Category 4 for species representing the only member of a monotypic family. This recognizes the unique taxonomic position of the aye-aye (Daubentonia madagascariensis) among Madagascar's lemurs and among the world's primates as a whole, as the only endangered monotypic nonhuman primate family. Also, in contrast to the two earlier primate action plans, associations with other threatened taxa are not used to rate the various taxa, but as a tool for assigning priorities to recommended conservation actions that are presented later in this document. Finally, slightly higher priority is given to those taxa not found in any officially protected areas.
The decision was made to use only rough estimates of total population sizes to assign degree of threat, rather than implement a classification proposed recently by Mace and Lande (1991). According to their re-evaluation of IUCN threatened species categories, taxa are classified as either critical, endangered, vulnerable or not at risk, this based upon numerical estimates of total and effective populations sizes, numbers and sizes of subpopulations, rates of population decline and the possible effects of catastrophic events. Although the Mace/Lande system may become the accepted format for future action plans, the compilers of this document feel that available information about Madagascar lemur numbers and population trends is not yet sufficient to warrant its use at this time.
Priority ratings for conservation action have been assigned to species and subspecies of Madagascar lemurs based on the following criteria:
Biological
Degree of Threat
Total population probably greater than 100,000.
Total population probably between 10,000 and 100,000.
Total population probably between 1,000 and 10,000.
Total population probably between 100 and 1,000.
Total population probably less than 100.
Taxonomic Uniqueness
A member of a large species group (i.e., one of several closely related species), or species status is sometimes questioned, but is at least a distinct subspecies.
A very distinct monotypic species, or one of a small number of closely related forms that together are clearly distinct from other species.
Only member of a monotypic genus.
Only member of a monotypic family.
Political
Level of Protection
One point is added to the priority rating if the taxon in question is not known to occur in any protected area.
Table 2 Conservation Priority Ratings for Lemurs
Table 3 Major Lemur Conservation Priorities by Taxa
