A new species of Diplothyrus (Parasitiformes: Neothyridae) from Brazil

Diplothyrus lehtineni n. sp. is described from adults females and males collected on surveys in the Brazilian Amazon forest. Measurements and illustrations of both sexes are provided. The presence of two modified setae on the palp genu, the absence of fringed seta on the palp genu and the absence of complex branched outgrowths on the chelicera characterizes this species. A description of Haller’s organ solenidia is also presented.


INTRODUCTION
The suborder Holothyrida is a small group of mites including 13 genera and 27 described species arranged into three families, Allothyridae, Holothyridae and Neothyridae (Beaulieu et al. 2011) , although a considerable larger species-level diversity is suspected, estimated to be between 160 and 320 species (Walter and Proctor, 2013 In Brazil, the Amazon forest is considered a biodiversity hotspot (Lewinsohn et al. 2005), but the distribution of many groups of mites, including to Neothyridae, is still poorly known. The only recorded species is D. schubarti, based on a male collected from Amazonas state and females from Para state (Bernardi et al. 2011).
Material collected in a survey in Para state allows us to describe here a new species of this poorly known group.

Study area
The specimens were collected in Martírios-Andorinhas National Park, located in the municipality of São Geraldo do Araguaia, along the Araguaia river in the south of Pará state, Brazil ( Figure 1). The Park is located in a transition area between the central Brazilian savanna, ecoregion Cerrado and the Amazon rainforest biomes, com-Vázquez Ma.M. et al.  posing mosaic ecotones with high biological diversity (Gorayeb et al. 2008). The Cerrado is a vegetation type of greater extent in Martírios-Andorinhas National Park, occupying over 80 km 2 . The second most important vegetation of region is the lower montane forest, found on the slopes and tops of mountains, and may occupy altitudes greater than 400 m, commonly interspersed with the Cerrado (Amaral et al. 2008).

Methods
The specimens were collected by Winckler extraction from litter and preserved in 70 % ethyl alcohol. The specimens were cleared in lactic acid, washed with distilled water, dissected and legs, infracapitulum, dorsal and ventral idiosoma and genital plates were mounted in Hoyer's medium on multiple slides.
Description and drawings were done with the aid of a Leica DM2500 phase contrast microscope equipped with a drawing tube. Uncoated specimens were also studied and photographed using a Scanning Electron Microscope (SEM, FEI Quanta 250) in environmental mode (ESEM). Measurements were taken using an ocular micrometer and are presented in micrometers (µm) ( Table 1).

Nomenclature
The nomenclature of setae and other morphological characters follows that of Hammen (1961

Diplothyrus lehtineni n. sp. (Figures 2-6)
Differential diagnosis -Thon's organ with 2 orifices inserted parallel to dorsal shield border, similar as in D. schubarti, but with two big and conspicuous membranous structures like funnels. Tibiotarsus with 6 modified serrated setae (5 inserted in line, plus 1 lateral). Two modified serrated setae on palp genu, but neither of them like the modified setae present on that of D. schubarti. Chelicera without complex branched outgrowth. Leg I with Haller's organ composed of a group of 7 highly modified sensillae.
Idiosoma -Dark brown, well-sclerotized, in shape of a large dome, with numerous long, serrated, terminally acute setae. Dorsal shield with light reticulation interrupted by numerous shallow, round indentations. Two pairs of dorso-lateral orifices (Thon's organ), the posterior orifice larger, surrounded by an ornamented funnel, the anterior one with an inverted funnel under the cuticle; both orifices are connected by a cuticular strip, inserted parallel to the dorsal shield margin (Figures 2A, 5B Figure 5C) which is extended between coxa I to coxa III.
Gnathosoma -Deutosternum well developed with numerous small teeth. Cuticular patterning limited to papillate zones on each side of deutosternum ( Figures 5C-D).
Subcapitulum ( Figures 2C-D) with 8-11 setae (males with 8, females with 11), hypostomal lobes with two median long setae. Corniculus horn-like inserted dorso-lateral. Lateral lips well developed with numerous small projections. Labrum well developed. Chelicera ( Figures 3A-B) well developed, 2 basal segments without setae; fixed digit with a small seta. Movable digit with one large tooth, a large terminal hook and numerous small, median teeth; fixed digit with two large and numerous small teeth. Membranous outgrowth not present, chelicerae covered by a membranous structure (Figure 3A-B).
Palp ( Figures 3C-D) -Trochanter with 2 setae, one with a bifurcate tip; femur with 20-21 setae and papillate cuticle; genu with 8-10 setae, two of them wide and serrate, the others acuminate; tibia with 60 curved, simple setae, and two al serrated setae, 6v strong and serrated setae and one sensilla. The modified setae on the genu are like a doubled setae, with serrated border ( Figure 3D).   Figure  3G). Under mesogenital valve a globose hyaline sac with long slim channels is visible and interpreted as a part of the ovipositor. One female was observed with two eggs. Male genital area ( Figures  4A and 5F) consisting of two plates positioned between coxae IV, anterior one with 17-18 large, lanceolate setae and posterior one without setae but with papillate cuticle. Males with distinct epiandrum. Legs ( Figures 4D-F and 6A-B) -Leg I Haller's organ ( Figures 4D-E and 6A-B) in the distodorsal part, comprising seven sensillae ( Figure 4D-E). All legs with a distinct basifemur. Leg I without acroor basitarsus. Leg setation on all segments based on whorls of 8 or 9 setae each. Tarsus I: The subterminal Haller's organ is in a depression with dense cluster of highly modified sensillae ( Figure 4D). Pretarsus I with almost sessile claws ( Figure 4E); pretarsi II-IV ( Figure 4F) with an ambulacral stalk carrying 1 pair of small setae, with well developed claws, and a large empodium.  Etymology -The species is dedicated to Dr Pekka T. Lehtinen, who has made significant contributions to the knowledge of Holothyrida.

DISCUSSION
The poorly made descriptions of Neothyridae species makes difficult to a proper comparison to D. lehtineni, besides their diagnoses are enough to confirm the new taxon. The main difference within Diplothyrus species are related to Thon's Organ position in relation to the dorsal shield border (Klompen, 2010), and number of modified setae on palps (Lehtinen, 1999). Acording with Lehtinen (1999) the Thon's organ is composed by two pairs of excretory glands furnished with a protruding membranous funnel.
The striking difference existing between D. schubarti and D. lehtineni is the different structure of Thon's organ. D. schubarti has one pair of membranous funnel in lightly more posterior position and another pair without funnel like extensions inmediately posterior to the stigma. In D. lehtineni the Thon's organ is composed by two pairs of funnels. One of them, the posterior is striking and membranous funnel, and the second funnel which is the an-terior, is located inside of the body but visible. Both of them are connected by a channel.
Another main difference in between D. schubarti and D. lehtineni is the absence in D. lehtineni of the specialized seta of the palpal genu, present in other holothyrids.
None of material analyzed of D. lehtineni present the antiaxial branched seta observed in D. schubarti, which is homologous with fringed seta presented on Holothyridae.
Diplothyrus lecorrei presents striking differences to D. schubarti and D. lehtineni, as the diagonal position of Thon's organ, superior number of subcapitulum setae (12, compared to 8-9 on D. schubarti and D. lehtineni) and smaller body size. All Neothyridae species present six modified palp tibia setae, but only D. schubarti presents the antiaxial branched seta on palpal genu. The depression on tip of tarsus I, a homologous structure to the Ixodida Haller's Organ, presents a broad solenidia in D. lehtineni, which is lacking in D. lecorrei. This comparison is not possible do D. schubarti due the absence of this information.
Chaetotaxy of tarsus I, palp articles and Thon's Organ position seem good characters to Neothyridae species comparison. We strongly recommend proper Neothyridae descriptions focusing on those to better comprehension of diversity and possible variations within such group.