Androlaelaps marmosops ( ACARI : LAELAPIDAE ) , A NEW SPECIES ASSOCIATED WITH THE MOUSE OPOSSUM , Marmosops incanus ( LUND , 1840 ) IN THE ATLANTIC FOREST OF RIO DE JANEIRO STATE , BRAZIL

Androlaelaps marmosops, a new species of laelapid mite, is described from the pelage of the mouse opossum, Marmosops incanus (Lund, 1840) (Mammalia: Didelphidae), in two areas of Atlantic Forest of Rio de Janeiro State. Measurements and illustrations are included for females only.


INTRODUCTION
During ecological studies in two areas of Atlantic Forest, a new mite of the genus Androlaelaps Berlese was found in the fur of the mouse opossum, Marmosops incanus (Lund, 1840).One of these localities was on Ilha Grande, an island just off the coast of Rio de Janeiro, at the CEADS/ UERJ, Centro de Estudos Ambientais e Desenvolvimento Sustentável (23 o 05'S; 44 o 12'W), municipality of Angra dos Reis, RJ; the other locality was on the mainland, in Serrinha do Alambari (22 o 23'S; 44 o 32'W), municipality of Itatiaia, RJ.
The cosmopolitan genus Androlaelaps Berlese is associated with the fur and nests of many species of mammals and, occasionally, of birds (Radovsky, 1994).The genus is very poorly known in the neotropics; the wide geographical distribution and morphological variation of some species, i.e., A. fahrenholzi (Berlese) and A. rotundus (Fonseca), indicate that they may represent complexes (Furman, 1972;Gettinger & Owen, 2000); many other unique species remain to be formally described.
Very little information is available on the laelapid mites associated with neotropical marsupials (Gettinger, 1997).Androlaelaps hirsuta Furman, A. tuberans Furman, and A. cuicensis Gettinger were also described from marsupials, and share some important characteristics with the new species described here.Guitton et al. (1986) report Androlaelaps guimaraesi (Fonseca) from Marmosops incanus on Ilha Grande, but we did not encounter this species in our studies.Samples of mites from the two areas were collected, fixed in 70% alcohol, and specimens were then mounted in Hoyer's medium on slides and examined with a microscope for analyses and taxonomic identification.Female mites predominated in the samples and there was not a sufficient number of males and nymphs to describe their life history stages.Eggs were found inside the opisthosoma of some female mites, but no larvae or nymphs were seen.This mite appears to be oviparous, differing from other laelapids mites associated with neotropical small mammals, like Laelaps e Gigantolaelaps, in which larvae and nymphs could be seen in the opisthosoma of the females.
We follow the concept of the genus Androlaelaps advanced by Till (1963), and use the system of setal nomenclature developed by Lindquist & Evans (1965).The measurements are in micrometers (µm) and expressed as: range, mean ± SE, n.The holotype and paratypes are deposited in the Museu Nacional do Rio de Janeiro (National Museum of Rio de Janeiro), Rio de Janeiro State, Brazil.Additional paratypes will be deposited in other collections.The host type specimen, and voucher specimens of Marmosops incanus are also housed in the Museu Nacional do Rio de Janeiro, Rio de Janeiro State, Brazil.

Diagnosis
The female is strongly distinguished from other neotropical species of the genus Androlaelaps by the following characteristics: 1. dorsal setae long and strong, j5 exceeding z5, reaching beyond insertion of j6; 2. sternal setae I inflated basely, not reaching beyond the insertion of sternal setae II; 3. proximal setae coxa I spur-like, inflated at base, with acuminate tips; and 4. pilus dentilis inflated.

Type material
Holotype: female (MN 12601) ex.Marmosops incanus (Lund, 1840), Serrinha do Alambari, municipality of Itatiaia, Estado do Rio de Janeiro, Brazil, collected 17/7/1997 by Helena de Godoy Bergallo.Holotype and paratypes were deposited in the arachnid collection of the Museu Nacional do Rio de Janeiro.Host voucher specimen HGB 57 (MN 48009) is in mammal collection of the Museu Nacional do Rio de Janeiro.Etymology: the species epithet refers to the genus of the host, Marmosops.
Distribution: known only from the type locality (Serrinha do Alambari, municipality of Itatiaia, Rio de Janeiro State, Brazil) and from Ilha Grande (municipality of Angra dos Reis, Rio de Janeiro State, Brazil).