Passalozetes (Passalozetes) alumbrensis, Martínez & Herrero, 2006

Martínez, Pablo A. & Herrero, Alfredo C., 2006, A new species of Passalozetes (Acari: Oribatida) from the Andes mountains of Argentina, Zootaxa 1160 (1), pp. 49-55 : 50-54

Passalozetes (Passalozetes) alumbrensis n. sp.

Adult

Size, sex, shape, colour: Length varies from 336 to 377 m, with an average of 353 m, and a width between 164 and 193 m, with 178 m in average, over 26 specimens measured, in cold lactic acid. Fourteen individuals were females and twelve males, indicating a sex ratio of 1:1. Differences of size between sex were not observed.

Oval, elongated body; length­width ratio near 2:1. Dark brown in colour.

Integument and cerotegument: Integument with linear ridges, or three­ or fourbranched ridges on areas of prodorsum and notogaster ( Fig. 1A , 2A ); on ventral region ridges more connected than on dorsal surface ( Fig. 1B ). On propodosomal and ventral plate borders ridges form a reticulated pattern. The soft junction skin between notogaster and prodorsum is smooth. Cerotegument completely covers body and legs, following sculpture of the integument. Cerotegument formed by columnar secretions of about 0.12 m in diameter and 0.36 m height, disposed in “rosettes” of 1 to 3 m in diameter ( Fig. 2C ). Under light microscopy, major rosettes stand out as separated small spherules in areas between ridges ( Fig. 1A ), even when the cerotegumentary layer is uninterrupted ( Fig. 2C ). Cerotegument also covers setae, at least proximally. Over the lenticular surface there is a continuous smooth secretion layer ( Fig. 2B ).

Gnathosoma, chelicerae, palps: Infracapitulum diarthric. Mentum reticulated, 45 m in length, genae and rutella 1/3 of mentum size. Chelicerae 75 m in length, movable digit (length= 20 m) with three teeth. Palp normal, tarsus minute (length= 13 m), palpatarsal solenidion close to aupathidium acm, but not strongly associated, both inserted distally.

Prodorsum: Two longitudinal, marginal costulae present, directed towards rostrum, extending 2/3 length of prodorsum; and weak, transverse ridge present, in front of the anterior limit of the notogaster ( Figs. 1A , 2A ). Interlamellar setae (in) minute (6 m), lamellar (le) and rostral (ro) setae medium sized (18 and 26 m respectively) and inserted on a same line, near each other. Setae ro inserted laterally. All prodorsal setae smooth. Bothridia with a low thickened border and a postero­lateral projection ( Figs. 1A , 2E ). Sensilli filiform, flat in section, pointed and reclined backwards, with small barbules on their posterior edge. Exobothridial setae (ex) minute (9 m), inserted below and slightly lateral to the bothridia, lodged in a depression ( Fig. 2E ).

Notogaster: long, length to width ratio = 1.4, protruding into prodorsum; dorsosejugal scissure not evident medially. At the humeral angles there are two small projections, as in the type species. Lenticulus present anteriorly with indistinct borders. Edge of lenticulus only evident by absence of integumental relief ( Figs. 1A , 2A, B ). Four pairs of small porose areas (5–8 m in diameter), three of those are visible in dorsal view ( Fig. 1A ) and the fourth pair, A 3, in posterior view ( Fig. 2D ). Porose areas covered with cerotegument; thus, their porosity is not evident ( Figs. 2D, F ). Fissures im well marked ( Fig 1A ); ip visible in posterior view ( Fig. 2D ); other fissures not conspicuous. Ten pairs of small (10 m around), smooth setae. Rugosity of the integument makes their observation difficult.

Lateral region: pedotecta I and II well developed. Subhumeral porose areas (Ah) visible ventral to humeral projections, as illustrated in the type species ( Grandjean, 1932, Fig. 2 ).

Ventral region: anal plates with longitudinal ridges; each with 2 setae (3 m in length). Genital plates have 5 pairs of setae (5–7 m length); anterior pair hard to see in some specimens under light microscopy, because inserted in the anterior border of the plate ( Fig. 2G ). Genital plates smooth, with relief produced by strings of cerotegument. Lyrifissures iad are in preanal position ( Fig. 1B ). Adanal setae (ad) are hardly visible, because of cuticular irregularities. Epimeral chaetotaxy is: 3­1­2­2; epimeric setae around 8 m in length. Ovipositor retracted inside the body is 75 m in length, and extended it reaches 150 m ( Fig. 2H ). Genital papillae subequal in size.

Legs: Porose areas present on femora (posterodorsally), tibiae (ventrodistally) and tarsi (ventral posterior side) ( Fig. 3 ), also on trochanters III and IV (paraxial surface, near the insertion). Tibiae I with well developed apophysis. Genua show a pair of ventral spurs, characteristic of genus ( Figs. 2 I, J ). Tarsi are heterotridactylous. Leg setae are serrated. Chaetotaxic formulae: I (1­4­2­4­15 + famuli), II (1­4­2­4­13), III (2­3­2­3­13), IV (1­2­2­ 3­12). Solenidiotaxic formula: I (1­2­2), II (1­1­2), III (1­1­0), IV (0­1­0).

Material examined

Twenty­six adults were observed. One holotype female and ten paratypes, stored in alcohol, are deposited in Museo Argentino de Ciencias Naturales “Bernardino Rivadavia”, Buenos Aires, Argentina and 15 paratypes are deposited in the senior author’s collection .

Locality

Cerro Alumbre (32º 47´56” S, 69º 22´05”), Andes mountains , Frontal cordillera, Uspallata region in the province of Mendoza, Argentina, at a height of 3853 m.a.s.l., under a Stipa sp. shrub .

Etymology Name refers to sample locality. Remarks

The five pairs of genital setae in P. (P.) alumbrensis allows distinction of alumbrensis from other species in the subgenus except for P. (P.) prominens Balogh & Mahunka from Córdoba, Argentina, which is the only other species known from the Neotropical Region ( Balogh & Balogh, 1990). This species differs from alumbrensis in microsculpture on the notogaster and lenticular outline. The absence of a clear outline of the lenticulus is a trait that alumbrensis shares with P. inlenticulatus Mihelčič, 1959 , from western Mediterranean, but differs from it in body size (larger in alumbrensis ), sensillus shape and notogastral microsculpture ( inlenticulatus description was taken from Pérez­Iñigo, 1993). Passalozetes (P.) alumbrensis resembles P. (P.) douglasensis Engelbrecht, 1974 , from South Africa, in sensillus shape and integumental ornamentation, but the lenticulus in douglasensis has a sharp outline and notogaster lacks humeral projections. The depression where exobothridial setae are lodged are not displayed in other Passalozetes species.

Discussion

Five pairs of genital setae, as present in P. (P.) alumbrensis , is a character state not included in the diagnosis of the Passalozetidae (where genital setae number is 4 pairs), even though this state was found in P. (P.) prominens Balogh & Mahunka 1968 , from Argentina. This character state implies the need for modification in the diagnosis of Passalozetidae , in order to include these taxa. Below, we present an extended diagnosis of this family, to include genital setal number, and other character states taken from literature:

Figures

FIGURE 1. Passalozetes (Passalozetes) alumbrensis n. sp. Adult. A. Dorsal view. B. Ventral view. Scale bar = 100 m.

FIGURE 2. Passalozetes (Passalozetes) alumbrensis n. sp. Adult. A. Prodorsum and anterior region of notogaster, with lenticulum. B. Surface of lenticulum. C. Detail of cuticular surface and cerotegument layer in ventral region. D. Posterior region of notogaster, left side. E. Bothridium and basal part of sensillus (image is rotated, arrow indicates dorsal face of organism). F. Porose area Aa, covered with cerotegument. G. Genital plates. H. Distal part and lobules of ovipositor, lateral view. I. Genu III in lateral view, showing ventral spurs. J. Idem in ventral view. Scale bars: A, D, G and H = 20 m; B = 4 m; C = 15 m; E, F, I, J = 10 m.

FIGURE 3. Passalozetes (Passalozetes) alumbrensis n. sp. Adult. A. Leg I, left, antiaxial view. B. Leg IV, left, antiaxial view. Scale bar = 50 m.