On the systematic of the water mites Oxus (Flabellifrontipoda) neotropica Lundblad, 1953 (Acari, Hydrachnidia: Oxidae)

The water mite Frontipoda (Flabellifrontipoda) neotropica Lundblad, 1953 was described from the male, female and deutonymph from Colombia (Lundblad 1953). This species was reported also from Chile (Besh 1964) and Argentina (Cook 1980, 1988). The original description of this species is incomplete and insufficiently illustrated. The male and female of F. neotropica were redescribed by Cook (1980) based on material from Argentina. The aim of the paper is to redescribe the deutonymph of this species and to specify somedetails in the adult mites. The material was collected by V. Stolbov in a streams in Chile. The material was sampled with a hand net with 250 μm mesh size. Mites were fixed in 75 % ethanol. Idiosomal setae and slit organs are named according to Tuzovskij (1987): Fch – frontales chelicerarum, Fp – frontales pedipalporum, Vi – verticales internae, Ve – verticales externae, Oi – occipitales internae, Oe – occipitales externae, Hi – humerales internae, He – humerales externae, Hv – humerales ventralia, Sci – scapulares internae, Sce – scapulares externae, Li – lumbales internae, Le – lumbales externae, Si – sacrales internae, Se – sacrales externae, Ci – caudales internae, Pi – praeanales internae, Pe – praeanales externae; i1 – i5 – slit organs. Furthermore, the following abbreviations are used: P–1–5, pedipalp segments (trochanter, femur, genu, tibia and tarsus) i.e. P-3 = genu; ac-1-3, genital acetabula 1-3; I–Leg–1–6 , first leg, segments 1–6 (trochanter, basifemur, telofemur, genu, tibia and tarsus), i.e. III– Leg–3 = genu of third leg;L – length; W – width, H height; n = number of specimens measured. All measurements are given in micrometers (μm), length of appendage segments is dorsal length.

The water mite Frontipoda (Flabellifrontipoda) neotropica Lundblad, 1953 was described from the male, female and deutonymph from Colombia (Lundblad 1953).This species was reported also from Chile (Besh 1964) and Argentina (Cook 1980(Cook , 1988)).The original description of this species is incomplete and insufficiently illustrated.The male and female of F. neotropica were redescribed by Cook (1980) based on material from Argentina.The aim of the paper is to redescribe the deutonymph of this species and to specify somedetails in the adult mites.

Systematics
Deutonymph.Idiosoma elongated, laterally compressed (Fig. 1).Lateral eyes not in capsules, lying below integument.Trichobothria Fp, Oi and setae Pi not associated with glandularia, other idiosomal setae associated with glandularia.Seta Fch longer and thicker than other idiosomal setae.Coxal plates large, fused on each side into two groups and occupying about one half of idiosoma surface.Two pairs of idiosomal setae and glandularia (Hv and Pe) incorporated into the coxal region on each side, other idiosomal setae and all slit organs located on soft integument.Glandularium Pe lying near tip of first coxal plate, accompanied by a hyaline projection and modified seta.Dorsum with two small oval anterior platelets bearing trichobothria Oi and three pairs traces of muscle attachment scars (Fig. 2), the latter usually hardly visible.Soft integument striated, surface of coxal plates porous.Genital field consisting of two very narrow lateral plates, two pairs of acetabula, three pairs of setae (one pair located anteriorly and two pairs posteriorly) and the small pregenital sclerite (Fig. 3).All acetabula subequal or posterior pair a little large than anterior pair.Excretory pore unsclerotized.
Figure 4 shows the lateral view of the capitulum and chelicera.Capitulum with a widely rounded protrusion a little distally to middle of ventral margin.Basal segment of chelicera large with convex dorsal margin, chela thin and pointed, sigmoid piece long and curved.Pedipalp (Fig. 5) small: P-1 without seta; P-2 ventral margin slightly concave or straight, with a single dorsoproximal seta and two unequal dorsodistal setae; P-3 with one short and one long dorsodistal seta; P-4 slender, longer than P-2, bases of ventral setae widely separated.
All legs located anteriorly.Shape and arrangement of setae on terminal segments of leg I and legIV as shown in figures 6 and 7, respectively.IV-Leg-5 with a single swimming seta (it is usually hardly visible), claws of IV-Leg-6 reduced but bearing two unequal heavy terminal setae.I-III leg claws (Fig. 8) pectinate, with three terminal clawlets (central clawlet much longer and thicker than internal and external ones) and numerous ventral teeth.
Dorsal strip bearing anterior pair of elongate dorsal platelets with trichobothria Oi(Fig.11), setae Ve, Hi, He, Sci, Li, Si,Pi and four pair slit organs (i2-i5).No true additional platelets in the dorsomedian strip, but as in the deutonymph there are some paired traces of muscle attachment scars, the latter are hardly visible.Genital field with three pairs of subequal acetabula or first pair a little larger than posterior pairs, each genital flap with 9-12 medial and 3-5 lateral setae.Excretory pore not sclerotized and located close to genital field.
The ventrolateral sclerotization of this species, except anteriodorsal setae, in corporating seven pairs of setae Hv, Oe, Sce, Le, Se, Ci and Pe (Fig. 9), glandularium Pe lying near tip of first coxal plate (Fig. 10) and are present also in all Oxidae (Di Sabatino et al. 2010).