Three new rotundabaloghid mites (Acari, Uropodina) from Sabah (Malaysia)

Abstract Three new species of the family Rotundabaloghiidae are discovered and described from Sabah, Malaysia. The unusual Angulobaloghia rutra sp. n. differs from the other known Angulobaloghia Hirschmann, 1979 species in the long anterior process of the female’s genital shield. Rotundabaloghia (Circobaloghia) tobiasi sp. n. has very long and apically pilose dorsal setae and two pairs of bulbiform setae, which are unique in the subgenus Rotundabaloghia (Circobaloghia) Hirschmann, 1975. The long, serrate and curved setae in the big ventral cavity of Depressorotunda (Depressorotunda) serrata sp. n. is a so far unknown character in the subgenus Depressorotunda (Depressorotunda) Kontschán, 2010.


Introduction
Mites of the family Rotundabaloghiidae distinctive within the Uropodina mites, having bodies that are small and rounded, ventral setae that are reduced and the marginal shield completely fused with the dorsal shield. The members of this family can be found in soil, leaf litter and moss in all tropical areas (Kontschán 2010a). Three groups of the family [the genus Angulobaloghia Hirschmann, 1979 and the subgenera Rotundabaloghia (Rotundabaloghia) Hirschmann, 1975 and Depressorotunda (Depressorotunda) Kontschán, 2010] are distributed only in the South-East Asian and Austral-Asian regions, one subgenus Depressorotunda (Amerorotunda) Kontschán, 2010 occurs only in South-America and the most species rich subgenus [Rotundabaloghia (Circobaloghia) Hirschmann, 1975] can be found in all tropical regions (Kontschán 2010b, 2011, Kontschán and Starý 2011, 2012. Currently four species are listed from Borneo (Kontschán 2010a) (where three countries, namely Malaysia, Indonesia and Brunie can be found), but so far no species are reported from Sabah (Malaysia). Searching the Arachnida collection of the Natural History Museum in Geneva revealed three new rotundabaloghid species in samples from Sabah, which are described in this paper.

Material and methods
Specimens were cleared in lactic acid and drawings were made with the aid of a drawing tube. The system of nomenclature for the ventral chaetotaxy follow Kontschán's (2010a). All specimens are stored in ethanol and deposited in the Natural History Museum in Geneva (MHNG). Abbreviations: h = hypostomal setae, St = sternal setae, im = internal malae, ad = adgenital setae, V = ventral setae. All measurements and the scales in the figures are given in micrometres (μm). Diagnosis. Genital shield of female with a long apical process and its surface covered by oval pits. Setae V7 and V8 smooth and needle-like, situated near end of pedofossae IV on small platelets. Setae on dorsal side of body pilose.
Legs (Figures 7-10). All legs with ambulacral claws and smooth and needle-like setae, femora II-Iv with flap-like ventral process.
Larva and nymphs, male unknown. Etymology. The name of the new species refers to the shape of the female's genital shield. The linguliform genital shield with the long apical process resembles a shovel (= rutrum in Latin). Remarks. The new species differs from the other known Angulobaloghia species by the apical process and pit-like ornamentation of the genital shield in females. Most other known Angulobaloghia species have female genital shields that are triangular, semicircular or bottle-like . Only one species [A. vietnamensis (Kontschán, 2008)] has a linguliform genital shield, but the apical process is short and spine-like. In contrast, females of the new species have a long and apically serrate genial process. Diagnosis. Genital shield linguliform, its surface with irregular pits and bearing a small spine-like process on anterior margin. Setae St1 and St2 bulbiform in females. Ventral setae V2, V6, V7 and ad short, V8 four times longer than other ventral setae. Dorsal setae long and apically pilose. Surface of dorsal shield with deep and oval pits.
Peritremes hook-shaped. Genital shield scutiform, surface smooth and its apical margin a little peaked. Pedofossae deep, their surface smooth, separated furrows for tarsi IV present. Base of tritosternum narrow, tritosternal laciniae smooth, subdivided into four smooth branches (Figure 26).  Gnathosoma ( Figure 26). Corniculi horn-like, internal malae smooth and very short. Visible hypostomal setae as follows: h1, h2 and h3 long (about 18-21 μm), smooth and needle-like. Apical part of epistome marginally pilose. Ventral side of palp trochanter with one needle-like and one robust and bifurcated setae, other setae on palp smooth and needle-like. Fixed digit of chelicerae longer than movable digit, internal sclerotized node present.
Larva and nymphs unknown. Etymology. The name of the new species refers to the serrate setae in ventral cavity.
Remarks. The long, robust, marginally serrate and curved setae on the big ventral cavity and the extreme long St4 setae in the species Depressorotunda (Depressorotunda) serrata sp. n. are previously not observed characters within the subgenus Depressorotunda (Depressorotunda) Kontschán, 2006.