The family Carabodidae (Acari, Oribatida) VIII. The genus Machadocepheus (first part) Machadocepheus leoneae sp. n. and Machadocepheus rachii sp. n. from Gabon

Abstract The genus Machadocepheus, being one of the more complex genera of the Carabodidae family, is briefly outlined to demonstrate this complexity. Descriptions of two new species from Gabon, Machadocepheus leoneae sp. n. and Machadocepheus rachii sp. n. are given.

With regard to Subias's recombination of genera and currently accepted classification of Machadocepheus, the changes were published and necessitate justification. We studied type material in order to not accepted. This paper specifically establishes the series of characters for the genus, and future papers will discuss other problems in terms of classification, in order to state reasons why the authors agree with some changes and disagree with others.
The genus is also complex in terms of the deposition of the type Machadocepheus excavatus Balogh, 1958 (see above). Balogh indicated in page 1 of his paper that "Les types des formes nouvelles que je decris ici font partie des collections du Musée Royal du "Congo Belge, a Tervuren", without further indications, but Mahunka 1986  First of all, the type material is not housed at the Museum Tervuren, and Mahunka never differentiated between IRAT and MRAT; MRAT most probably refers to the Musée Royal du Congo Belge Tervuren, and we suppose that the type material discussed by Balogh in 1958, and possibly that of Mahunka 1986, is housed in the latter.
We studied most species cited, except for Machadocepheus manguiati Corpuz-Raros, 1979, which we were unable to obtain, and Machadocepheus longus Balogh, 1964, which was not available on loan from HNHM. We were fortunate to later obtain large quantities of specimens (from Madagascar) in the Betsch Collection of the Muséum National d'Histoire Naturelles (MNHN), Paris, France, and were able to conduct observations using both SEM and optical microscopy. The situation Machadocepheus longus Balogh, 1964 will the subject of a subsequent paper.
This paper, the eighth in the series on the revision of the family Carabodidae will be structured as follows: initial studies of a series of new species, making use of SEM and optical microscopy in order to permit understanding of the structures involved. Thereafter, we aim to study type material where only optical microscopy studies are available (or possible), with the intention of clarifying the taxonomy of Machadocepheus and related genera.

Material and methods
Specimens studied by means of optical microscopy were macerated in lactic acid and observed in the same medium using the open-mount technique (cavity slide and cover slip) described by Grandjean (1949) and Krantz and Walter (2009). Drawings were made using a Zeiss Axio Scope (Carl Zeiss Microscopy GmbH, Jena, Germany) compound microscope equipped with a drawing tube.
Specimens were also studied with the aid of Scanning Electron Microscopy (SEM). Specimens preserved in ethanol were carefully rinsed by sucking them into a Pasteur pipette several times, after which they were transferred to buffered glutaraldehyde (2,5 %) in Sörensen phosphate buffer (pH 7,4; 0,1 m) for two hours. After postfixation for two hours in buffered 2% OsO4 solution and being rinsed in buffer solution, all specimens were dehydrated in a series of graded ethanols and dried in a critical point apparatus. After mounting on Al-stubs with double sided sticky tape, specimens were gold coated in a sputter apparatus (Alberti and Fernandez 1988). The critical point appar-atus used was an Emitech K 850 (Quorum Technologies Ltd., Ashford, Kent, United Kingdom) and the sputter a Jeol JFC-1200 (Jeol Ltd. Tokyo, Japan) (metalized 80").
SEM observations were very complex, due to limited numbers and anatomic particularities shown by specimens. Two different types of SEM were used in order to obtain observations of adequate quality: 1) Tescan Vega II LSU (Tescan Orsay Holdings, Kohoutovice, Czech Republic) (Direction of Collections-SEM-EDS-MNHN) and 2) Hitachi SU3500 (Hitachi High-Technologies Europe, Krefeld, Germany) (Plateau technique de Microscopie Electronique et de Microanalyse (PMEM) (MNHN) using accelerating voltage of 15 Kv and 10 Kv respectively.
In the legends to Figures, images obtained with Tescan Vega II LSU are indicated with a small number 1 and those obtained with Hitachi SU3500, with a small number 2.
Measurements taken: total length (tip of rostrum to posterior edge of notogaster); width (widest part of notogaster) in micrometers (μm).
Leg chaetotaxy studies executed with the aid of standard, polarized and phase contrast microscopes are provisional, due to the fact that only adult specimens were available for study. Setal formulae of the legs include the number of solenidia (in parentheses); tarsal setal formulae include the famulus (ε).

Morphological terminology and abbreviations
Morphological terms and abbreviations used are those developed by F. Grandjean (1928Grandjean ( -1974
Supratutorial depression with three pocket depressions, one internal, another anterior and a third posterior to supratutorial depression. Bothridia cup-shaped with smooth bothridial ring and bothridial tooth. Lyrifissures ih, ips present. Subcapitular setae h on large promontories. Epimere 1 with two promontories; epimere 2, one promontory; epimere 3 two promontories; epimere 4 two promontories. Epimeral chaetotaxy 3-1-3-3; anterior aggenital furrow present. Genital plate small in relation to anal plate; four pairs of genital setae; two pairs of anal setae; aggenital and adanal setae similar in length and shape; lyrifissures iad well discernible between ad 3 and ad 2. Several large and small depressions visible on lateral anal plate.
Tutorium: rod-like curving cuticular thickening; supratutorial depression present; along with three pocket-shaped depressions, one anterior tutorial depression, one posterior tutorial depression and a small depression situated internally to supratutorial depression. Pedotecta I, prominent extended lamina, rounded apex; Pedotecta II small, ovoid lamina. Lyrifissures ih, ips clearly visible. Discidium: polyhedral structure with rounded apex. Depressions behind acetabulum IV; one of them elongated, concealing tarsus during folding legs process. Series of aligned depressions in medial zone. Epimeral chaetotaxy 3-1-3-3; anterior genital furrow clearly visible; four pairs of long genital setae; two pairs of small anal setae; anal plate terminating in small sharp tip; aggenital and adanal setae similar length; lyrifissures iad not discernible.

Discussion
Intricate structural shapes and the need to observe specimens from various angles and positions made many structures difficult to understand when only using optical observation. Comparing these species with others from the same genus was greatly complicated by very short and superficial original descriptions, and some errors were detected in descriptions of various species of the genus Machadocepheus as well as in related genera (Bathocepheus, see ; Tuberocepheus see Fernandez et al. 2014). Much care had to be taken not to create any further confusion in the genus Machadocepheus and related genera, and for the reasons cited above we deemed it necessary to continue our study of a number of related genera in a series, discussed in future papers, to try to understand the existing problems.