Demodectic Mites of Subhuman Primates I: Demodex saimiri sp. n. (Acari: Demodicidae) from the Squirrel Monkey, Saimiri sciureus

Abstract

A new mite species, Demodex saimiri, is described from the squirrel monkey, Saimiri sciureus. All stages are found in the hair follicles and sebaceous glands. Adults and immatures consume cells of the follicular epithelium and/or sebaceous glands. An incidence of 57% is reported, with 67% incidence in female and 47% in male host animals. Population studies indicate a sex ratio of 1:5, suggesting arrhenotoky. Only four species of Demodicidae have been described from primate hosts to date. Two of these are from a lemur (Fain, 1959), the other two from man (Desch and Nutting, 1972). A description of Demodex saimiri is provided below with some information on its relationships with the host, Saimiri sciureus. MATERIALS AND METHODS Mites were obtained by scraping the host skin and mounting debris in Hoyer's medium; these preparations were examined under phase contrast and light optics. Skins of Saimiri sciureus were purchased from biological supply companies, or loaned or donated by colleagues; all work was done on preserved materials, except for 2 live hosts, which did not prove to have detectable mite populations. Sixty host animals (30 male, 30 female) were examined. Screening of the hosts involved scraping the shoulder area and part of one eyelid; if one or both of these regions was found to harbor mites, further materials were taken from muzzle, belly, axilla, nipple, genitalia, and perianal area. Skin specimens taken from regions found by scrape technique to have high mite populations were embedded in paraffin, sectioned at 8 /,m, and stained with Harris' hematoxylin and eosin for study of mites in situ. All measurements in the description are presented in micrometers: mean and standard deviation for 20 specimens. Demodex saimiri sp. n. (Figs. 1-13) Description (including characters of the genus) Of average length in comparison to other members of the genus; adult almost 10 times as long as wide; total length quite variable. No marked sexual dimorphism. Received for publication 15 December 1972. * Present address: 1735 LeRoy Avenue, Berkeley, California 94709. Males (Fig. 5): Gnathosoma length about equal to width. Palp with 2 movable segments and a cluster of claws. Supracoxal spines small; discshaped base with gently curved thin process directed mediad (Fig. 2). Pharyngeal bulb horseshoeshaped, open posteriorly; subgnathosomal setae minute, anterolateral to pharyngeal bulb (Fig. 1). Four pairs of 3-segmented legs evenly spaced along podosoma; visible from dorsal aspect; each with 3-pronged claws; single solenidion on legs I and II. Genital orifice dorsal, nonoperculate; slightly posterior to first pair of dorsal tubercles over legs II; all tubercles figure-8-shaped, anterior pair more widely spaced than posterior (Fig. 3). Penis long (17.0 ? 1.8) and slender, gently curved, sheathed, swollen at base. Several transverse striations on dorsal surface over legs IV. Last epimeral plates with distinct posterior sutures. Opisthosoma finely annulate, long, without proctodeum; bluntly pointed at posterior extremity. Females (Fig. 6): Gnathosoma slightly longer than wide. Mouth parts, supracoxal spines, pharyngeal bulb, and subgnathosomal setae as in male. Podosomal contours, proportions, striations, and leg positions same as male. Vulva a simple ventral slit 7.1 ? 0.6 long, just posterior to sutures of last epimeral plates (Fig. 4). Proctodeum irregularly tube-shaped, opening about 30 annulae from posterior end and running posteriorly. Other opisthosomal features as in male, but overall length greater (see Table I). Ova (Fig. 7): Fusiform, anterior end more rounded than posterior. Length (20 specimens) 69.7 ? 6.2, width 21.9 + 1.4. Shell thin, transparent; posterior pigment granules inconspicuous. Larvae (Fig. 8): Slender, tapered posteriorly; mouthparts well developed, palps with single lateral spine and cluster of claws. Pharyngeal bulb visible; subgnathosomal setae absent. Three pairs of stubby legs, each with a single trifid claw; no epimeral scutes. Protonymphs (Fig. 9): Elongate; mouthparts and legs as in larvae, but proportionately larger, and legs with 2 trifid claws; 3 pairs of crescentshaped epimeral scutes, ventral, in line with leg pairs. Attenuated posterior with fine striae. Nymphs (Fig. 10): Elongate; mouthparts and