Monotremes

Abstract: The first South American monotreme is described from early Paleocene [Tiupampian] sediments in Patagonia, Argentina. Monotrematum sudamericanum n. gen. & n. sp., represented by a single upper second molar, is the first monotreme known from ...

Nocturnal mammals can be challenging to survey and especially for many species that live in dense forest habitats limited information is available on densities and distributions. We surveyed the endemic Javan slow loris Nycticebus javanicus in the montane forests of Mt Gede Pangrango, West Java, Indonesia. Surveys were conducted on 23 transects (260 hours covering some 93 km) using variable speeds between 200-800 m/hr. Densities on individual transects varied from 0 to 52 individuals / km2, with an overall density of 15.6 individuals / km2 [95% Confidence Intervals 9.7-25.2 individuals / km2]. Encounter rates per km were strongly influenced by the speed at which transects were walked with less lorises detected at higher speeds. This effect was absent when considering encounter rates per hour. Detectability of Javan slow lorises was not affected by the amount of lunar light and we found no obvious differences in slow loris behaviour and moonlight. Part of the study area comprised disturbed forest but encounter rates did not differ between disturbed or primary forest. Our study shows that slow lorises are not homogeneously distributed in their montane habitat and occur at relatively low densities. Unlike some of their congeners we found no evidence for lunar phobia or lunar phillia. A comparison with other surveys of lorisiformes reveals no statistically significant relationship between survey effort or the speed at which transects are walked and estimated densities but speed is positively correlated with encounter rates. 

Key words: Indonesia, survey methods, lunar phobia, mammal, conservation, ecology

We describe an additional fragmentary upper molar and the first lower molar known of Monotrematum sudamericanum, the oldest Cenozoic (Paleocene) monotreme. Comparisons suggest that the monotreme evolution passed through a stage in which their molars were “pseudo−triangulate”, without a true trigonid, and that the monotreme pseudo−triangulate pat− tern did not arise through rotation of the primary molar cusps. Monotreme lower molars lack a talonid, and consequently there is no basin with facets produced by the wearing action of a “protocone”; a cristid obliqua connecting the “talonid“ to the “trigonid” is also absent. We hypothesize that acquisition of the molar pattern seen in Steropodon galmani (Early Cre− taceous, Albian) followed a process similar to that already postulated for docodonts (Docodon in Laurasia, Reigitherium in the South American sector of Gondwana) and, probably, in the gondwanathere Ferugliotherium.