Two zoogeographically remarkable mite species from Finland (Acari, Oribatida, Oribotritiidae)

Diagnosis of Maerkelotritia cryptopa (Banks, 1904) and description of a new species Austrotritia finlandica sp. nov. are given. The first‐mentioned species, previously recorded from the Nearctic Region, can now be considered as a holarctic species. The second species belongs to the genus Austrotritia Sellnick, 1959 from the southern hemisphere. Thus, it is highly unexpected to find it in Finland.


Introduction
The paper reports the finding of two species (in two genera) of oribatid mites which have not been previously reported from Finland. One of the genera, Maerkelotritia Hammer, 1967, represented by Maerkelotritia cryptopa (Banks, 1904), has hitherto been found only from the Nearctic Region (Niedbała 2002). The other genus, Austrotritia Sellnick, 1959, is a typical genus of the southern hemisphere, where it frequently occurs in Oriental and Australian Regions.

Diagnosis
Prodorsum with setae erect, interlamellar and lamellar setae rigid covered with small spines; rostral setae with flagellate distal tip, rough. Notogaster with rather short (c 1 ,c 1d 1 ), rigid setae covered sparsely with small spines. Genital plates with 6-10 pairs of setae; anal plates with one, two, or three pairs of setae; adanal plates with four pairs of fairly long setae. Chaetome of legs variable (Table II).

Remarks
The specimens from Finland have slightly shorter notogastral setae, wider distance between setae ad 2 -ad 3 than between ad 1 -ad 2 or ad 3 -ad 4 , and highly varied number of anal setae. The species is also characterized by variability in the chaetotaxy of genital setae and chaetome of the setae of the legs (Tables I, II). Number of genital setae is six, eight, nine, or 10. Number of anal setae is one, two, or three pairs; mostly a long an 1 in the posterior part of the plate and a short an 3 in its anterior part. Two specimens also have a seta an 2 in the middle part of the plate and one specimen has only seta an 3 . Leg chaetome is variable in setae of femora: I (3 or 4), II (3 or 4), III (2 or 3), IV (2 or 3), and genua IV (2 or 3).

Comparison
Despite the large variation in the number of genital setae, especially anal setae, this species is distinguishable from the similar Maerkelotritia kishidai (Aoki, 1958) by the permanent presence of a short anal setae (an 3 ) in the anterior part of each anal plate. Maerkelotritia kishidai always has one pair of anal setae an 2 in the middle part of the anal plates. Table I. Numbers of setae on left and right sides of the genital and anal plates of seven specimens of Maerkelotritia cryptopa (Banks, 1904 --an 3 --a n 3 Specimen 2 8 8 an 1 an 2 an 3 an 1 -a n 3 Specimen 3 9 9 an 1 -a n 3 an 1 -a n 3 Specimen 4 9 10 an 1 -a n 3 an 3 9 an 1 -a n 3 Specimen 5 9 9 an 1 an 2 an 3 an 1 an 2 an 3 Specimen 6 9 9 an 1 -a n 3 an 1 -a n 3 Specimen 7 8 10 an 1 -a n 3 an 1 -a n 3 Table II. Chaetome of legs (without tarsi) of Maerkelotritia cryptopa (Banks, 1904).
Ventral region. Setae h of mentum longer than distance between them. Palps fivesegmented with chaetome: 0-3-0-2-9(1). Genitoaggenital plates with two transversal furrows. Nine pairs of genital setae, two pairs anteriorly of first furrow, two pairs anteriorly of second furrow, and five pairs posteriorly of second row. Two pairs of aggenital setae present. Anal plates with one pair of setae. Adanal plates with three pairs of setae; lyrifissures iad are located laterally between setae ad 2 and ad 3 .

Discussion
The finding of the new species representing the genus Austrotritia in Finland is highly unexpected. The species of this genus have previously been recorded from the southern hemisphere, mainly from the Oriental and Australian Regions. However, the ranges of individual species have reached further to the north, namely to the Palaearctic Region and its eastern, southern and western borders, more specifically to the islands of Japan (Aoki 1980(Aoki , 1988, to Kashmir and Nepal (Niedbała 2000), and to the Canary Islands (Pérez-Iñ igo 1986). Maerkelotritia cryptopa has hitherto been known only from the Nearctic Region. The locality in Finland extends its geographic distribution and permits an assumption of it as a holarctic species. The specimens of Maerkelotritia cryptopa from Finland differ from the specimens from the Nearctic Region in a few minor morphological features (Niedbała 2002), mainly by the great variation in the number of anal setae. It also differs in the variation of the chaetotaxy of genital setae and the chaetome of leg setae. A constant character is the presence of seta an 3 in the anterior part of the anal plate.