Six new species of ptyctimous mites (Acari: Oribatida) from Madagascar

Six new species of ptyctimous oribatid mites from Madagascar are described and illustrated: Oribotritia perpusilla n. sp.. and Phthiracarus ranomafanensis n. sp. from Ranomafana National Park; Euphthiracarus (Euphthiracarus) paranetron n. sp. and Atropacarus (Hoplophorella) parastenos n. sp. both from Montagne d’Ambre National Park; Phthiracarus paracrispus n. sp. from Ankarafantsika National Park; Notophthiracarus medius n. sp. from Andasibe – Mantadia National Park. A comparison with the most closely related species is also presented.


INTRODUCTION
Madagascar hosts some of the World's most diverse, unusual, endemic fauna and flora. This unique biodiversity and high level of endemism seem to be related to long-term isolation from neighbouring continental landmasses and the highly diverse environment. This fourth largest island in the World is classified as one of the most important biodiversity hotspots (Myers et al. 2000).
Dr P. Baňař (Brno, Czech Republic), in official co-operation with the University in Antananarivo (Antananarivo, Madagascar), organized the search for litter-inhabiting invertebrates, mainly different groups of insects, in the years 2010-2015 in various parts of Madagascar. Together with his collaborators Dr R. Raveloson, Dr E. M. Rabotoson and Dr L. S. Rahanitriniaina, he collected large samples of litter invertebrates, which were kindly offered for our study. This contribution is partly a continuation of our study of ptyctimous mite fauna based on this material (Niedbała and Starý 2013;2014a, b, c;2015a, b, c).

MATERIALS AND METHODS
The soil samples were collected by using a leaf litter sifting method and were extracted using a Winkler apparatus. All of the extracted mite specimens were preserved in 85 % ethanol, then cleared on slides with 80 % lactic acid and mounted on temporary slides with glycerol. Observations, figures and measurements were made using a standard light microscope equipped with a drawing attachment. The determined materials were preserved in vials with 80 % ethanol. All measurements are given in micrometres. Specimens shorter than 600 µm are considered small, while longer than 1 mm are large. The term c 1 /c 1 -d 1 indicates the ratio of length of setae c 1 to the distance between setae c 1 -d 1 . The terminology is based on Niedbała (2000 Prodorsum -with distinct, long and simple lateral carinae. Sensilli long, bent in proximal part, smooth. Other prodorsal setae short, interlamellar (in) and rostral (ro) setae erect, rough, lamellar setae (le) procumbent, smooth, exobothridial setae (ex) vestigial.
Ventral region -Setae h of subcapitular mentum shorter than distance between them. Anogenital cleft trv long. Nine pairs of genital and two pairs of equal aggenital setae present, genital setae g 1-5 longer than setae g 6-9 . Anal plate without setae and three pairs of adanal setae present. Distance between adanal setae ad 1 and ad 2 slightly longer than between ad 2 and ad 3 . Lyrifissures iad situated laterally between adanal setae ad 2 and ad 3 .
Etymology -The name of the new species perpusillus is Latin for "very small" and alludes to the small size of body in comparison with congeners.
Comparison -The new species differs from its congeners by the small size, the long, simple lateral carinae of the prodorsum and long, bent sensilli, absence of anal setae and presence of three pairs of adanal setae.
Medium-sized species. Colour yellow. Surface of body reticulate.
Ventral region -Setae h of subcapitular mentum longer than distance between them. Nine pairs of genital setae with formula 8: 1, two pairs of rather long aggenital setae. Anal setae an 1 and an 2 shorter, slender and thinner than adanal setae ad 1 and ad 2 . Lyrifissures iad situated between adanal setae ad 2 and anal setae an 3 .
Etymology -The prefix para is Latin meaning "near" and refers to the similarity the of the new species with the species Euphthiracarus netron Niedbała et Starý, 2014.
Comparison -The new species is distinguishable from the similar E. netron Niedbała et Starý, 2014 by the reticulation of body surface (versus punctuation of surface), presence of two pairs of lateral carinae of prodorsum (versus one pair), slightly different shape of sensilli, with head like elongated spindle (versus short spindle), longer exobothridial setae ex, longer than distance between setae le and ro (versus shorter than le-ro), longer setae h of mentum than distance between them (versus setae h shorter), arrangement of genital setae: 8: 1 (versus arrangement 7: 2) (Niedbała and Starý 2014b).
Prodorsum -with median and lateral fields distinct long and narrow. Lateral carinae long, exceeds the sinus. Posterior furrows not visible. Sensilli (ss) long, thin, smooth, enlarged in their proximal third and ending in a point. Interlamellar (in) and lamellar (le) setae fine, smooth, semi-erect; rostral setae (ro) curved and directed downwards; exobothridial setae (ex) rather long, almost as long as ss and ro; relative length of prodorsal setae in>le>ro=ss>ex.
Notogaster -with fine, rather long notogastral setae (c 1 >c 1 -d 1 ); setae c 1 and c 3 slightly remote from anterior notogastral margin, setae c 2 far from the margin. Vestigial notogastral setae f 1 located posteriorly of h 1 setae; two pairs of lyrifissures ia and im present.
Legs -Chaetome of legs complete; setae d of femora I thin, remote from distal end of article.

Phthiracarus ranomafanensis n. sp. (Figures 4)
Notogaster -with 15 pairs of fine, attenuate and very short notogastral setae, setae c 1 shorter than half of distance between setae c 1 -d 1 . Setae c 1 and c 2 remote from anterior margin of notogaster, setae c 3 situated near this margin. Vestigial setae f 1 located anterior of h 1 setae (left side of holotype) or at the level of h 1 setae (right side of holotype). Four pairs of lyrifissures ia, im, ip and im present.
Ventral region -Setae h of subcapitular mentum slightly longer than distance between them. Formula of genital setae 4: 5. Anoadanal plates with 5 pairs of very short setae, adanal setae ad 1 the longest. Adanal setae situated near paraxial border of plates, adanal setae ad 1 at the level of anal setae an 1 and adanal setae ad 2 at the level of anal setae an 2 .
Legs -Chaetome of legs of "complete type"; setae d of femora I long, robust and slightly remote from distal end of article.
Etymology -This new species is named after Ranomafana National Park.
Comparison -The new species has the arrangement of genital setae similar to that of some South African species of the genus Phthiracarus such as P. densus Niedbała , 2006, P. endroedii (Mahunka, 1984 (Niedbała 2006). It is easily distinguishable from its congeners by the unusual arrangement of adanal setae situated near paraxial borders, adanal setae ad 1 and ad 2 at the level of anal setae an 1 and an 2 , very short and fine notogastral setae, and by the presence of four pairs of notogastral lyrifissures.
Notogaster -Surface of notogaster covered with small alveoles connected with weak lines, resembling reticulation. Notogastral setae robust, bacilliform of medium length (c 1 <c 1 -d 1 ), their distal half covered with small spines. Notogastral setae c 1 and c 3 situated close to anterior margin of notogaster, setae c 2 remote far from this margin. Vestigial notogastral setae f 1 not visible, vestigial setae f 2 and two pairs of lyrifissures ia and im present but hardly perceptible.
Ventral region -Setae h of subcapitular mentum shorter than distance between them. Surface of genitoaggenital and anoadanal plates reticulated. Formula of minute genital setae: 5: 4. Anoadanal plates each with 5 pairs of setae, two pairs of anal setae thinner and three pairs of adanal setae thicker, adanal setae ad 1 and ad 2 longest.
Legs -Setation of complete type. Setae d on femora I bifurcate and situated at distal end of article.
Etymology -The specific name of the new species medius is Latin for "intermediate", "between" and refers to the similarity of the new species to two Notophthiracarus species N. lineatus Niedbała et Starý, 2015 andN. reticulatus Niedbała et Starý, 2014. Comparison -The new species is similar to N. lineatus in the shape of the notogastral surface, which is covered by small foveolae connected with weak lines. It is also similar to N. reticulatus in the overall image of reticulation on the surface of notogaster.. New species is distinguishable from N. lineatus by baciliform shape of sensilli (versus dilated distally), longer adanal setae ad 3 (versus minute adanal setae) and bifurcated setae d of femora I (versus not bifurcate). The new species is distinguishable from N. reticulatus also by bacilliform sensilli (versus dilated head of sensilli), erect interlamellar setae (in) and minute lamellar setae (le) shorter than rostral setae (ro), (versus almost procumbent interlamellar setae (in) and lamellar setae (le) longer than rostral (ro) ones, by setae h of mentum shorter than distance of their insertion points h<h-h (versus longer setae that distance of their insertions, h>hh; by adanal setae ad 2 of anoadanal plates, which are remote from paraxial margin of plates (versus location of adanal setae ad 2 near paraxial margin). Starý 2014c, 2015b Species of rather small size; colour yellow; surface of body covered with deep rounded foveoles, in anterior part of notogaster with irregular margin.
Prodorsum -with small median crista. Lateral carinae short, posterior furrows distinct. Sigillar fields feeble, median ones narrow and longer than laterals. Sensilli (ss) rather short, with narrow pedicel and club-shaped, distally rounded head covered with small cilia. Other prodorsal setae minute, needleform, similar in length, ss>ro>in=ex>le.
Notogaster -with needleform, attenuate and smooth notogastral setae, most of them characteristically bent, medium in the length (c 1 <c 1 -d 1 ); notogastral setae c 1 and c 3 slightly remote from anterior notogastral margin, setae c 2 far from the margin. Vestigial setae and lyrifissures not visible.
Ventral region -setae h of subcapitular mentum considerably longer than distance between them.
Legs -Formulae of setae and solenidia of "complete type"; setae d on femora I needleform and situated at distal end of article.
Etymology -The prefix para is Latin meaning "near" and refers to the similarity the new species with A.(H.) stenos Niedbała et Starý, 2014. Comparison -The new species is slightly similar to A. (H.) stenos Niedbała et Starý, 2014 from Tanzania in the shape of the sensilli and shape and length of prodorsal, genital, anal and adanal setae. The new species is distinguishable from A. (H.) stenos by the absence of powerful median crista of prodorsum and anterior cowl of notogaster, curved notogastral setae, longer setae h of the mentum (versus shorter setae) and setae d of femora I situated at distal end of article (versus remote from distal end) (Niedbała and Starý 2014a).