Nothrus separatum, Nakamura & Nakamura & Fujikawa, 2013

Nakamura, K., Nakamura, Y. - N. & Fujikawa, T., 2013, Oribatid Mites (Acari, Oribatida) From Tohoku (Northeast Japan), Collected After A Tidal Wave In 2011, Acarologia 53 (1), pp. 41-76 : 53-56

Nothrus separatum n.sp.

[Japanese name: Suehiro-amimeonidani] ( Figures 10 – 11 )

Diagnosis — Body length 807 µm; width 386 µm. Prodorsal surface punctulate and irregularly alveolate. Notogastral surface medially and laterally tuberculate; alveolate between medial and lateral portions. Rostral incision short. Sensilli long, rod-like bearing sparsely spins. Notogaster anteriorly broadly rounded, posteriorly roundish angular, with a pair of longitudinal ridges extending from c -series line to insertion of seta f 1. Of all notogastral setae, f 1 the longest. Solenidia ’ 1 and σ longer than each dorsal seta. Genito-anal setal formula: 9-0-2-3. Subcapitulum diarthric, subcapitular setae: 1-2-1. Epimeral setal formula: 11[9]-5-6-5. Heterotridactylous.

Material examined — Holotype (Adult female) (NSMT-Ac 13634) from sand, soil and humus at point B.

Etymology — After longitudinal ridges on notogaster divergent posteriorly

Measurements and body appearance — Body length 807 µm; width 386 µm. Body colour light brown. Prodorsal surface punctulate and irregularly alveolate. Notogastral surface medial and lateral portions of notogastral surface tuberculate; surface between medial and lateral portions alveolate.

Prodorsum — Rostral incision short ( Fig. 10B ). Transversal ridge distinct between insertions of setae ro, and between those of setae le. Setae ro (21 – 23 µm), le (45 µm) and in (50 µm) thick, short rod-like, closely barbed. Sensilli (179 µm) long, rod-like bearing sparsely spins ( Fig. 10A ). Bothridia cup-shaped, opening dorso-laterally. Setae ex (30 µm) barbed setiform inserting at the basal portion of bothridium. Lateral prosomatic mark (m) distinct anterolaterally to bothridium.

Notogaster — Anterior margin broadly rounded; posterior margin roundish angular; a pair of longitudinal ridges extending from c -series line to insertion of seta f 1, not joining posteriorly. Of all 16 notogastral setae, the longest f 1 (89 µm), the shortest c 2 = c 3 (39 µm). Lyrifissures ia aligned obliquely posterior to c 3; im longitudinally, between d 3 and e 2; ip perpendicular, postero-laterally to gla; ih and ip s situated ventrally ( Fig. 11A ). Relative distances: (f 1 - f 1: 571 µm)>(e 1 - e 1: 104 µm)>(d 2 - d 2: 89 µm)>(h 1 - h 1: 75 µm)>(p 1 - p 1: 68 µm)>(c 1 - c 1: 54 µm) = (d 1 - d 1).

Ventral region — Genito-anal setal formula: 9-0- 2-3; all setae spiniform; anal setae sparsely barbed, other setae smooth ( Fig. 11B ). Genital (35 µm) and anal (24 µm) setae inserting at the inner margin of each plate. All adanal setae (51 µm) aligned in adanal. Lyrifissures ani and adi aligned almost longitudinally at the level setae ad 3. Subcapitulum diarthric, subcapitular setae: 1-2-1; setae h (26 µm), A (40 µm), m 1 (20 µm), m 2 (14 µm) smooth spiniform. Epimeral setal formula: 11[9]-5-6-5; all setae (14 µm) thin, short, smooth setiform. Epimeral borders distinct.

Legs — Heterotridactylous; claw (40 µm) sparsely, minutely dentate ( Fig. 11F ). Setal formula: I (1-9-5-6-26), II (1-9-5-5-26), III (4-6-5-5-22), IV (1-6- 5-5-20). Solenidiotaxy: I (1-2-3), II (1-1-1), III (1-1-0), IV (1-1-0). Measurements (µm) of segments: [Rightleft]

I ([71-61]-[164-164]-[89-89]-[79-82]-[148-154]),

II ([71-71]-[136-136]-[71-75]-[61-68]-[125-125]),

III ([71-71]-[100-100]-[64-61]-[61-57]-[129-139]),

IV ([107-107]-[114-125]-[68-71]-[71-68]-[182-182]).

All legs bearing one solenidion of all tibiae and genua contiguous to dorsal seta ( Figs. 11 D-E). On tarsus I ( Fig. 11C ), famulus ε (4 µm) spiniform situated antero-laterally to ω 1 (35 µm), posterior to solenidia ω 2; ω 2 (16 µm), postero-laterally to ω 3 (14 µm); ω 2, ω 3 thin bacilliform; ω 1 thick bacilliform, broad basally, situated anterior to seta ft ’ (67 µm). Solenidia ’ 1 and σ longer than each dorsal seta. On tibia I, solenidion ’ 1 (39 µm) and ’ 2 (16 µm) setiform, situated on every apophysis; ’ 1 contiguous to smooth spiniform seta d (26 µm), inserting anterior to d. On genu I, σ (21 µm) spiniform, contiguous to smooth cone-like seta d (10 µm) situated on a small apophysis.

Remarks — The new species is similar in shape of prodorsal and notogastral setae, and notogaster with one pair of longitudinal ridges to Nothrus discifer Hammer, 1961 and T. gracilis Hammer, 1961 . However, the new species differs from those species in having the longest setae not h 2 or p 1, but f 1 of all notogastral setae, and longitudinal ridges not joining posteriorly.

Figures

FIGURE 10: Nothrus separatus n.sp. (Holotype NSMT-Ac 13634): A – Principal setae: lamellar seta le, interlamellar seta in, notogastral seta c1, sensillus ss, exobothridial seta ex; B – Rostral region; C – Dorsal view.

FIGURE 11: Nothrus separatus n.sp. (Holotype NSMT-Ac 13634): A – Ventral view; B – Principal setae: Anterior (a), medial (m1-2), posterior (h) setae, epimeral seta (1a), genital (g), anal (an), and adanal (ad) setae; C – Solenidial region on right tarsus I; D – Solenidial region on left tibia I; E – Solenidial region on left genu I; F – Tip of right leg III.