Populatoon variation and systematics of the genus Lophuromys peters, 1874 (Rodentia, muridae)

Santiapillai, Charles Valentine Manoranjan (1975) Populatoon variation and systematics of the genus Lophuromys peters, 1874 (Rodentia, muridae). University of Southampton, Doctoral Thesis.

Abstract

The genus Lophuromys, commonly known as the Harsh-furred mouse or the Brush-furred field mouse is found only in Tropical Africa. itch of the early work on this genus was directed chiefly towards the identification and description of a number of species and subspecies. This work was later augmented with studies on the ecology of the genus. However, until now, no critical study has been carried out to characterise the pattern of variation in populations of this genus.This work attempts to study the variation shown in populations of, Lophuromvs. A total of 1,070 skulls and 668 skins from 53 localities and representing eight species of Lophuromys were used in the study. The pattern of variation was studied using both continuous characters such as linear measurements as well as discontinuous characters such as epigenetic variants. A total of 26 continuous and SO discontinuous characters were studied in each skull. Colour variations in the skins were examined with the help of M resell Soil Colour Charts. The skulls were aged according to the degree of tooth-wear. Eight age classes were devised. To prevent bias due. to different age-classes in populations, allowances were made by adding a series of adjustments to the original measurements of the skulls in order to bring them to a uniform age-class. The study of variation of the continuous characters was divided into two sections. Firstly by means of a univariate analysis using four skull characters, the pattern of variation in each species was studied, A measure of the correlation between the 26 characters was they calculated. Secondly, all the 26 characters were studied simultaneously in a multivariate analysis in which canonical variates were computed. The generalised distance between every pair of populations was calculated, for four species. By using these generalised distance values, affinity dendrograms were obtained for both intraspecific and interspecific populations. The affinity dendrogram revealed the presence of two groups of, Lophuromys, corresponding to the short- and long-tailed groups. Within/the short-tailed group, two sub-groups were obtained, one representing L.imelanonyx and the other consisting of L. sikapusi, L - arpilus and L. flavopunctatus. The dendrogram showed that the last two species were extremely similar. L. rahmii although a short-tailed species' was found to occur in the long-tailed group. But, it was found to be quite distinct from the other three species, namely L. woos, L. luteogaster, and L. medicauciktus which formed a sub-group. Thirty discontinuous (epigenetic) characters were used in the study of intraspecific variation Sex difference in. the incidence of these characters was found to be insignificant. BI using the percentage incidence of all these characters, measures of divergence were calculated between pairs of populations. The epigenetic analysis showed geographical groupings in the case of populations of L. sikapusi, whose epigenetic variation broadly paralleled the continuous variation. The analysis also showed that the island population from Bukasa Island, Uganda, was the most distinct. Out of the four characters that were studied in populations of L, sikanusi, three characters were found to vary clinically from West to East Africa. The phenetic affinities of the genus was studied by comparison with ten other African rodent genera. It was found that Lophuromys,shares phenetic affinity with Zelotomys, Praomys and Uranomys. The systematic position Of the species and subspecies was re-examined. It was concluded that Lophuromys aquilus was a synonym of L. flavopunctatus. A number of spades described in the original literature have been reduced to subspecific status and some discarded. The origin of the group seems to be from the East African highlands from where three lines of evolution emerged. One represented by L. woosnami is endemic to the area and restricted to montane forests. The second, represented by L. flavopunctatus, extends from North and South and the third line, represented by L. silmpusi, spreads to West Africa. The genus seems to be extremely successful in' Tropical-Africa.

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