Notes on the Biology of the Central American Squirrel, Sciurus richmondi

Abstract

Additional specimens of Sciurus richmondi are reported, along with comments on variation, distribution, reproduction and molt in this little kno.on squirrel. As presently understood, S. richmondi occurs only in the Caribbean rain forests of Nicaragua. Significant secondary sexual variation in adults was found only in zygomatic breadth, in which females are the larger. Available evidence reveals that the breeding season extends at least from February to September, and suggests two seasonal molts annually. INTRODUCTION Sciurus richmondi was named and described by Nelson (1898: 146), based on a series of specimens collected by Charles W. Richmond in 1892 on the Rio Escondido above Bluefields, Departamento Zelaya, Nicaragua. Subsequently, ]. A. Allen (1908:660; 1910: 104) recorded several specimens from the Caribbean drainage of central Nicaragua, but we are unaware of reports of additional material since Allen's second paper. In recent studies in Nicaragua, 53 specimens of S. richmondi have been collected, providing noteworthy data on the biology of this poorly known sciurid. VARIATION In the original description and in subsequent publications '(Nelson, 1899:101; Hall and Kelson, 1959:395), Sciurus richmondi has been characterized as closely related to S. granatensis, recorded from northern Costa Rica southward into South America. Nelson (1898: 147) supposed it probable that the two intergraded. S. richmondi differs principally from the North American subspecies of S. granatensis-hoffmanni of Costa Rica, chiriquensis of Costa Rica and Panama (these two represent but a single subspecies according to Harris, 1943:9-10) and morulus (choco, a synonym according to, Handley, 1966:777) of Panama-in being smaller, both externally and cranially, slightly less richly colored overall, and in having conspicuously paler bands on the hairs of the tail (tawny ochraceous as opposed to fulvous or buffy orange). We agree that richmondi resembles granatensis in general features and admit the possibility that the two may be found to be conspecific. Nevertheless, we are reluctant at this time to consider richmondi as a subspecies of granatensls because of the great size difference in the specimens available to us. The smallest adult granatensis that we have seen is a female '(KU 60478) from El Dragon, 26 km S San Jose, Costa Rica, in which the greatest length of skull is 53.1 mm, whereas the largest richmondi is a male from El Rccreo with a greatest length of skull of 51.5 mrn (Table 1). The only indication of possible intergradation now available between the two taxa is revealed by a male (skin only) from Cataratas San Carlos, Costa Rica (AMNH 141922), which differs from other Costa Rican granatensis in that both dorsal and ventral sides of the tail are considerably less reddish-orange; the tail of this specimen thus closely resembles those of our Nicaraguan squirrels 'in color. Jones & Genoways in American Midland Naturalist (July 1971) 86(1). Copyright 1971, University of Notre Dame. Used by permission.