A new species of Fissicepheus and a supplementary description of Leptotocepheus murphyi (Mahunka, 1989) (Acari, Oribatida, Otocepheidae) from Malaysia

This work includes taxonomic data on two species of oribatid mites of the family Otocepheidae from Malaysia. A new species of the genus Fissicepheus is described. Fissicepheus parastriganovae n. sp. differs from Fissicepheus striganovae Ermilov and Anichkin, 2014 by body ornamentation, length of interlamellar and notogastral setae and morphology of genital plates. The species Leptotocepheus murphyi (Mahunka, 1989) is recorded in Malaysia for the first time. A supplementary description of this species which was originally described from Singapore is given on the basis of the Malaysian specimens. The main morphological traits for L. murphyi are summarized.


Introduction
This work is based on the random set of the Malaysian oribatid mite (Acari, Oribatida) material, which was received from the collection of the Institute of Zoology (Slovak Academy of Sciences, Bratislava, Slovakia), and includes data on the family Otocepheidae.
In the course of taxonomic identification we found two otocepheid species, one species belonging to the genus Fissicepheus Balogh and Mahunka, 1967 is new to science, and the other is a known species, Leptotocepheus murphyi (Mahunka, 1989); both are from the nominative subgenera.
The primary goal of our paper is to describe and illustrate a new species under the name Fissicepheus parastriganovae n. sp. Fissicepheus was described by Balogh and Mahunka (1967), with Fissicepheus elegans Balogh and Mahunka, 1967 as type species. The genus comprises two subgenera and 27 species (Subías 2019). The generic diagnosis was presented by Balogh and Mahunka (1967) and Aoki (1967). The nominative subgenus comprises 26 species, which are distributed in the Palaearctic and Oriental regions (Subías 2019). An identification key to known species of the subgenus is provided by Zheng and Chen (2018).
The secondary goal of our paper is to present a supplementary description of L. murphyi, adding new figures and information about morphological variability and some morphological structures and their measurements, identification of leg setae and solenidia and morphology of the gnathosoma, which will assist with identification of this species in the future. Leptotocepheus murphyi was found earlier in Singapore and Vietnam (Mahunka 1989;Ermilov and Bayartogtokh 2015). Thus, it is the first finding of this species in Malaysia.

Methods
Specimens were mounted in lactic acid on temporary cavity slides for measurement and illustration. Body length was measured in lateral view, from the tip of the rostrum to the posterior edge of the notogaster. Notogastral width refers to the maximum width of the notogaster in dorsal view. All body measurements are presented in micrometers. Formulas for leg setation are given in parentheses according to the sequence trochanter-femur-genu-tibiatarsus (famulus included). Formulas for leg solenidia are given in square brackets according to the sequence genu-tibia-tarsus.
Drawings were made with a camera lucida using a Leica transmission light microscope "Leica DM 2500". SEM photos were made with the aid of a JEOL-JSM-6510LV SEM microscope.
Morphological terminology used in this paper follows that of F. Grandjean: see Travé and Vachon (1975) for references, Norton (1977) for leg setal nomenclature, and Norton and Behan-Pelletier (2009), for overview.
Legs (Figs 3a, 3b, 4a Type deposition -The holotype is deposited in the collection of the Institute of Zoology, Slovak Academy of Sciences, Bratislava, Slovakia; seven paratypes are deposited in the Table 1 Leg setation and solenidia of adult Fissicepheus parastriganovae n. sp. and Leptotocepheus murphyi (Mahunka, 1989).

Leg Tr
Fe Ge Ti Ta Remarks -Fissicepheus parastriganovae n. sp. is morphologically most similar to Fissicepheus striganovae Ermilov and Anichkin, 2014 from Vietnam in having simple costulae, phylliform interlamellar, notogastral and adanal setae, and long bothridial setae, and the development of all prodorsal and notogastral condyles; it differs from the latter by the presence of partial foveolate body ornamentation (only on anal plates and in medioposterior part of notogaster versus prodorsum, notogaster and anogenital region completely foveolate), interlamellar setae clearly shorter than notogastral setae (versus similar in length) and more long notogastral setae (45-49 versus 24-32), and the absence of longitudinal stria on genital plates (versus present).
Pedotecta I represented by large lamina, pedotecta II represented by small lamina. Discidia elongate triangular.
Comparison -Our specimens of L. murphyi are morphologically identical to the Singapore specimens from the original description (Mahunka 1989). Only one slight difference is present: bothridial setae usually distinctly dilated mediodistally versus bothridial setae near setiform, slightly dilated in median part (only one our specimen has similar structure of bothridial setae).
Also, we have found that sometimes the median unpaired notogastral condyle is lacking in four males in Malaysia versus always developed. Thus, these morphological nuances must be considered in future identifications of L. murphyi.

Discussion
The otocepheid genera Leptotocepheus and Dolicheremaeus Jacot, 1938 are morphologically similar in many main traits except one: Leptotocepheus with unpaired median notogastral condyle versus this unpaired condyle always absent and instead of it the paired medial condyles often present in Dolicheremaeus.
Leptotocepheus murphyi was described by Mahunka (1989) as the representative of the genus Dolicheremaeus Jacot, 1938. Ermilov (2015 and Ermilov and Bayartogtokh (2015) used the new generic position for this species (genus Leptotocepheus), and, later, the new systematic placement of L. murphyi was supported by other authors (e.g., Subías 2016Subías , 2019Ermilov and Minor 2018). This confusion is connected with one important morphological nuance: the species is unusual because its anteromedial part of notogaster has simultaneously three tubercles (one median unpaired condyle, and paired medial condyles). Based only on the presence of the paired medial condyles, Mahunka (1989) included L. murphyi in Dolicheremaeus, сonsidering most likely that the unpaired median condyle is additional (not basic). On the contrary, Ermilov (2015) and Ermilov and Bayartogtokh (2015) considered that the unpaired median condyle is basic (paired medial condyles are additional, not basic), therefore, they included the species in Leptotocepheus.
Our data on morphology of the Malaysian specimens of L. murphyi show presence and absence (seldom) of unpaired median notogastral condyle in different specimens, and this situation creates additional confusion about which notogastral condyles to consider basic or additional (unpaired median condyle or paired medial condyles). Thus, in this moment, based on the presence of unpaired median notogastral condyle (in typical case), we continue to consider the species as representative of Leptotocepheus, but its placement may be revised in the future (for example, after genetic analysis).