Scutovertex pilosetosus Poldermann, 1977

Pfingstl, Tobias, Schäffer, Sylvia, Ebermann, Ernst & Krisper, Guenther, 2009, Differentiation between two epilittoral species, Scutovertex arenocolus spec. nov. and Scutovertex pilosetosus Polderman (Acari: Oribatida) from different European coasts, Zootaxa 2153, pp. 35-54 : 41-45

Redescription of Scutovertex pilosetosus Poldermann, 1977

Diagnosis. Mean body length 675 µm, mean body width 429 µm. Dark brown cuticle. Pusticulate cuticle over the whole body with irregularly distributed foveae on notogaster. Long cusps, weakly developed median ridge between lamellae. Sensillus, short, slightly capitate, spinose. 10 pairs of spiniform and slightly serrate notogastral setae. Seta la twice as long as seta c2. Transverse ridge on mentum lacking. Legs slender. Chaetome: I (1-4-3-4-18), II (1-4-3-4-15), III (2-2-2-3-15), IV (1-2-2-3-12). Solenidia: I (1-2-2), II (1-1-2), III (1-1-0), IV (0-1-0).

Morphology of the adult (N=8, 4 males and 4 females)

Body length: 655–718 µm (mean 675 µm / m = 659 µm, f = 690 µm). Body width: 403–477 µm (mean 429 µm / m = 414 µm, f = 443 µm). Colour brown to dark brown. Outline of body oval.

Prodorsum ( Fig. 8a ). Cuticle strongly pusticulate. Sensillus short, slightly capitate and serrate. Bothridia strong cup-like projections, showing a small apophysis on antiaxial side of margin with a ridge running ventrally. Interlamellar or exobothridial setae absent. Lamellae well developed, slightly converging, connected by small translamella. Between bothridia two strongly convergent ridges, fused in the middle of interlamellar field. Fused ridge weakly developed running towards translamella not reaching it. Cusps long, bearing thin and spiniform lamellar setae (le), bent to median axis. Rostral setae (ro) completely smooth, of approximately the same length as le.

Gastronotic region ( Fig. 8a ). Cerotegument forms polygonal spots consisting of densely packed granules. Cuticular foveae with indistinct margin distributed irregularly over notogaster. Lenticulus with concave lateral borders, posterior part broader than anterior part. Ten pairs of notogastral setae present ( Fig. 8c ): c2, la, lp, dm, h1-3, ps1-3. Setae c2 short, acute. Seta la spiniform, twice as long as c2. Setae lp, dm slightly serrate and spine shaped. Setae h1-3 slightly broadened distally and serrate. Setae ps1-3 short with rounded tip, seta ps1 the longest and seta ps3 the shortest. Humeral angle conspicuously developed. Five pairs of lyrifissures present: ia, im, ih, ips and ip; ia located on a small cuticular nodule under humeral angle. Lyrifissure im broad, situated laterally between setae la and lp, ih and ips positioned laterally on a level near posterior lateral border of notogaster anteriorly seta ps3. Lyrifissure ip in posterior part of notogaster situated between setae h1 and ps2. Orifice of opisthonotal gland situated laterally to seta lp, well discernable. Three pairs of exiguous sacculi represent elements of the octotaxic system. Two small median emarginations of cuticle on posterior part of notogaster.

Subcapitulum and camerostome. Cuticle strongly pusticulate. Border of rostrum showing an apical lobelike projection and lateral triangular longish lamellae originating from the posterolateral corner of camerostome. Consistent rostrophragma around camerostome reaching articulation of subcapitulum. No transverse ridge on mentum. Seta h long and acuminate. Genae with solid and slightly pectinate setae a and m. Rutellum with three teeth, first one largest. Pedipalp pentamerous; chaetome: 0-2-1-3-9 (solenidion excluded).

Ventral region of idiosoma ( Fig. 8b ). Cerotegument forms polygonal spots consisting of densely packed granules; weaker developed in the epimeral region. Epimeral setation (I-IV): 3-1-2-2. Pedotectum I well developed, hiding completely acetabulum I, pedotectum II large, Y-shaped in dorsal view. Apodemes I and II reaching median axis, apodeme III small and apodeme IV absent. Genital setation 6+6 (variations 5+6 or 6+5). Genital valves anteriorly broadened and surrounded by cuticular grooves. The anterior one arcuated rostrad, the posterior one slightly curved caudad crossing transversely whole ventral region. Posterior half of ventral region strongly pusticulate. One pair of short spiniform aggenital setae ag1. Anal valves posteriorly broadened. Two pairs of anal setae, an2 situated on the anterior third and an1 on the posterior half of anal plates. Three pairs of long acuminate adanal setae ad1-3. Lyrifissure iad flanking anterior end of anal orifice. Preanal organ broad, shaped cup-like.

Legs ( Figs. 9a–d ). Tridactylous, heterodactylous. Lateral claws thinner, all three claws dorsally slightly dentate. Cuticle slightly rugose, with a few strong ribs on trochanter to tibia. All limbs shaped noticeable slender. Ventral and lateral setae on tibia and tarsus slightly serrate. Solenidia ϕ 1 and ϕ 2 located on large apophysis of tibia I. Femora I and II provided with bifurcated trachea, one long branch reaching into tibia and a short branch ending within the femur, spiracles opening dorsally on axial side of femur. Leg III–IV show simple trachea from femur to tarsus; stigma located proximally dorsally in a paraxial crevice of femur. Trochanter III–IV also equipped with trachea, curving along the inner wall. Chaetome: I (1-4-3-4-18), II (1-4- 3-4-15), III (2-2-2-3-15), IV (1-2-2-3-12). Solenidia: I (1-2-2), II (1-1-2), III (1-1-0), IV (0-1-0).

The eggs of S. pilosetosus were only investigated by means of light microscopy ( Fig. 10 ). The egg shell seems to consist of irregularly shaped mushroom like structures which are densely distributed over the whole surface.

Figures

FIGURES 8 a – c. S. pilosetosus. a, dorsal view; b, ventral view; c, notogastral setae.

FIGURES 9 a – d. S. pilosetosus, right legs (leg I and II depicted without trochanter, dashed lines represent tracheae). a, leg I antiaxial view; b, leg II antiaxial view; c, leg III antiaxial view; d, leg IV axial view.

FIGURE 10. S. pilosetosus, eggs photographed through body wall.