Neocarus caipora, a new mite species (Parasitiformes: Opilioacarida: Opilioacaridae) from brazilian Amazon caves

A new species of the genus Neocarus (Parasitiformes: Opilioacarida: Opilioacaridae), Neocarus caipora n. sp. is described and illustrated from brazilian Amazon caves.


INTRODUCTION
The Opilioacarida is one of the smallest orders of mites. Only 11 genera, 38 species and one subspecies have been described so far. Of these, only two genera, but almost half of the species (17) and the unique subspecies have been described from the New World. Within that subset of taxa, most were described from North and Central America (Chamberlin and Mulaik 1942;Juvara-Bals and Baltac 1977;Klompen 2002, 2009 (Bernardi et al. 2012;Bernardi et al. 2013a;Bernardi et al. 2013b;Hammen 1969;Lehtinen 1980;Silvestri 1905). In this study we describe a new species of Neocarus from North of Brazil.

MATERIALS AND METHODS
All specimens were collected by hand from caves, searching under stones, in organic matter accumulations, cracks in the soil and were stored in vials with 80 % ethanol.
Most material was studied as slide-mounted specimens. For this purpose, specimens were dissected (due to size), cleared in Nesbitt's solution and mounted on slides using Hoyer's medium (Walter and Krantz 2009).
Drawings were prepared using a Zeiss Axioscope 3 phase contrast microscope, connected to a drawing tube; measurements are presented in micrometers (µm) and were taken using a Nikon Eclipse 90i automated DIC microscope.

Differential diagnosis
The new species and Neocarus potiguar are the only ones in the genus with triangular male genital valves (these valves are rectangular or weakly curved in other congeners), and just one pair of lateral seta on acrotarsus II-IV (Figures 1-2). However, in N. caipora n. sp. the female lacks pre-genital setae (present in N. potiguar) and the number of the ch-type setae on the palp tarsus is less than in N. potiguar (12 -14 vs. 25 -27).
N. potiguar and N. caipora are currently the only species in South America with curved dorsal and apically pectinate lateral setae on ambulacra II -IV. This character is shared with some North American species, such as Neocarus texanus Chamberlin and Mulaik 1942, N. siankaanensis Vázquez and Klompen 2002, N. bajacalifornicus Vázquez and Klompen 2002  setae. Setae ch1" and ch2" smooth, cht and ch2' lightly barbed (only visible at high magnification). Dorsal (id) and antiaxial lyrifissure (ia) well developed. Fixed digit with 1 tooth, movable digit (63 -68 µm) with 1 tooth and a well developed terminal hook. Movable digit with two ventral denticles in the basal portion. A third, but small and weakly visible denticle was observed only in 3 females. One or two rounded membranous processes present in middle of the anterolateral portion. Internal surface of movable digit with a small sensillum.
Subcapitulum - (Figures 4A-C). All 4 pairs of paralabial setae present: pl1 small, conical; With's organ (pl2) membranous and barbed marginally; rutella (pl3) with one distinct row of 5 teeth, inserted dorso-lateral; pl4 very small, inserted dorsal. With 4 circumbuccal (cb), and 5 -10 median and subcapitular setae. Seta vm1 in all adults with rounded tip and robust, similar to circumbuccal setae. Females with one, rarely two (N=1), additional pairs of median setae with rounded tips (indicated by arrows in Fig. 4A). All setae in the median area of the subcapitulum in males show a fine, attenuated tip. Canals (ogl1 and ogl2) on lateral lips distinct.
Idiosoma - (Figure 5). Color light with dark blue patches. Body sometimes with a brownish background resulting from ingested food. Dorsal shield with 108 -139 ribbed setae and two pairs of eyes. One pair of lyrifissures present. Rostrum rounded. Dorsal portion of idiosoma between the shield and the preanal segment without setae, but with numerous lyrifissures arranged in transverse rows. Preanal segment with 1 dorsal and 2 lateroventral setae; anal plates in adults each with 9 -10    stout, ribbed setae.
Sternitogenital region - (Figure 6). Sternapophyses with two setae, one small seta at the tip and one long and barbed seta positioned more basal. Sternal verrucae in adults each with 1 long, tapering (St1), and 2-3 smaller setae. Remaining sternal area with 2 pairs of tapering (St2 and St3) and 3-4 pairs of long, ribbed setae, and 3 pairs of lyrifissures (two pairs very large, the third smaller; all different in shape and size from "standard" opisthosomal lyrifissures). Setae St2 slightly longer than St3. Pregenital capsules each with 1 long tapering seta (St5) and 4-5 ribbed setae. Pregenital and genital area in male with, respectively, 4-8 ribbed, stout setae and 5-8 tapering and ribbed setae. In females, pregenital area nude and genital area with 8-12 smooth and pointed setae. Ovipositor consisting of a tube-like structure. A single pair of gland-like structures in its median portion, and apex convex.
Acrotarsus of leg II with a dorsal bifurcate seta and two smooth sensilla (one long and other small) resembling solenidia (Figure 2). Acrotarsi of legs III-IV carry just 3 long, barbed and tapering setae dorsally. Additionally, acrotarsi II-IV carry 3 pairs of smooth ventral setae, 1 pair of lightly barbed ventrolateral setae (positioned distally), 1 pairs of smooth lateral setae and 1 pair of smooth laterodorsal setae (positioned distally). Pretarsi in all instars with one pair of claws and 2 pairs of setae, one pair long and curved, and other smaller and apically pectinate. Pretarsal ambulacrum rounded and smooth. Coronidia limited to basitarsi II-IV.
An important observation made during the biological survey was the presence of two species of Opilioacaridae in the same site (cave) and sometimes next to each other, sharing the same microhabitat (under rocks and in litter on soil). This unusual mix seems to confirm that Opilioacaridae are not very aggressive and/or territorial. Previous observations by Vázquez and Palácios-Vargas (1988) and Klompen (2000) showed similar lack of aggression. Aggregation behavior in Brazilian Neoacarus species was already noted by Bernardi et al. (2012). Another factor facilitating coexistence may be body size, since adult N. caipora are significantly smaller than the adults of the Caribeacarus brasiliensis Bernardi et al. 2013 found in the same area. Adult N. caipora are similar in size to nymphal (deutonymph and tritonymph) C. brasiliensis, which may avoid competition between adults.