Tectocepheus acutus, 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 : 60-63

Tectocepheus acutus n.sp.

[Japanese name: Togari-kuwagatadani] ( Figures 15 B-G – 16)

Diagnosis — Average body length 282 µm; width 171 µm. Rostral anterior margin without incision, broadly rounded with rostral trowel. Lamellar cuspis with dents bilaterally to lamellar seta, not extending to level of rostral anterior margin. Setae in roughened rod-like. Sensilli with spinose, clavate head and smooth, thin stem. Bothridia with deep

F – Solenidial region on right genu III; G – Chelicera (B, F: Holotype NSMT-Ac 13630; C, C, E, G: Paratype NSMT-Ac 13631) .

incision, without swelling or projection. Depressions and dorsosejugal scissure absent. Humeral region with small triangular projection. Ten pairs of notogastral setae. Genito-anal setal formula: 6- 1-2-3. Lyrifissures iad located along, near anterior margin of anal aperture. Epimeral setal formula: 3- 1-3-3. Trochantera III and IV bearing carina with sharply pointed apex. Monodactylous.

Material examined — Holotype (Female) (NSMT-Ac 13630) from point B; 1 paratype (NSMT- AC 13631 ): same data as holotype.

Etymology — After long, sharply pointed apex on trochanter III.

Measurements and body appearance — Body length 279 – 286 µm; width 164 – 179 µm. Body colour light brown. Whole body surface covered with cerotegument; cerotegument irregularly dark granulate.

Prodorsum — Rostral anterior margin without incision, broadly rounded with rostral trowel ( Fig. 15C ). Rostral setae (16 µm) consisting of unilaterally spinose head and thick, smooth stem, inserting dorsally under lamellar cuspis. Lamellar cuspis with dents bilaterally to lamellar seta, not extending to level of rostral anterior margin; outer dent longer than inner dent. Inner sides of cuspides straight. Setae le (33 µm) setiform minutely roughened, strongly curved inside. Setae in (7 µm) minutely roughened rod-like. Sensilli (46 µm) composed of thin, roughened stem and globular head bearing dark coloured spines. Setae ex (4 µm) smooth, short bacilliform. Bothridia opening antero-laterally, with deep incision, without swelling or projection.

Notogaster — Depressions and dorsosejugal scissure absent. Dorsophragmatic apophysis (hy) conspicuously long. Humeral region with small triangular projection ( Fig. 15B ). Ten pairs of notogastral setae short (4 – 7µm) setiform, roughened throughout length. Lyrifissures ia aligned longitudinally or obliquely, lateral to setae c; im obliquely, lateral to gla; ih, ip and psi perpendicular to notogastral outline. Relative distances: (h 3 - h 3: 120 µm)> (h 2 - h 2: 95 µm)> (lp -lp: 88 µm)> (h 1 - h 1: 43 µm)> (lm -lm: 34 µm)> (p 1 - p 1: 18 µm).

Ventral region — Genital (31 µm) and anal (55 µm) apertures almost pentagonal in shape; distance (23 µm) between them appreciably shorter than half length of anal aperture. Genito-anal setal formula: 6-1-2-3; all setae smooth setiform ( Fig. 16 ). Setae g 1 and g 2 (9 µm) not inserting at the same level at anterior margin of plates. Setae ag (8 µm) inserting latero-posterior to genital aperture. Setae ad 1 and ad 2 (10 µm) aligned in postanal position, ad 3 (7 µm) in adanal; ad 3 inserting almost at mid-distance between an 1 and an 2 (7 µm). Lyrifissures iad located along, near anterior margin of anal aperture with enclosed angle 120-140º. Sternal ridge indistinct. Epimeral borders 1-4, sj distinct. Epimeral setal formula: 3-1-3-3; setae smooth, short setiform (3 – 7 µm). Subcapitulum diarthric, subcapitular setae 3 pairs, A (14 µm), m (14 µm), and h (11 µm); setae thin smooth setiform. Cheliceral setae cha (23 µm), chb (16 µm) thin, barbed setiform. Trägårdh’s organ short (14 µm), with a blunt apex ( Fig. 15G ).

Legs — Monodactylous; claw (21 µm) sparsely dentate dorsally. Setal formula: I (1-5-3-4-18), II (1-5-3-4-14), III (2-4-1-3-14), IV (1-2-2-3-10). Measurements (µm) of right segments according to depressed paratype: I (25-40-16-31-35), II (21- 46-14-25-28), III (50-36-14-26-23), IV (51-43-21-?-?). Trochantera III – IV and femora III-IV bearing carina; trochantera III with long, sharply pointed apex (21 µm) bending to rostral side ( Fig. 16 ). On tarsus I, famulus ε (9 µm) consisting of a fine tip and expanded basal portion, situated antero-laterally contiguous to ω 2; ω 2 (31 µm) terminating in fine tip; ω 1 (21 µm) bacilliform situated posterior to ω 2; ft ’ (8 µm), inserting posterior contiguous to ω 1 ( Fig. 15D ). Solenidion ’ 2 (15 µm) originating from a small apophysis on the tip of tibia I; ’ 1 (65 µm) situated at the base of apophysis. On genu I, solenidion σ (18 µm) terminating in a fine tip, longer than seta d (8 µm) ( Fig. 15E ). All solenidia on tarsus II, tibiae II-IV and genua II-III short rod-like (σ III: 7 µm), shorter than each dorsal seta (d III: 11 µm) ( Fig. 15F ) .

Remarks — The new species is similar to Tectocepheus minor Berlese, 1903 in shape of dentate cuspis and small enclosed angle of lyrifissure pair iad, however, the former is different from the latter in shape of bothridial ventral extension, long sharply pointed carina on trochantera III, arrangement of genital setae, and solenidia of legs ( Laumann et al., 2007; Nübel-Reidelbach, 1994). The new species is similar in shape of long sharply pointed carina on trochantera III, and shape, length and situation of solenidia, famulus and seta ft ’ on tarsus I to T. kumayaensis Nakamura et al., 2010 . However, the new species differs from the latter in having a round rostrum, dentate cuspides, lyrifissures im located laterally to opisthonotal gland gla and genital setae aligned almost in a line. The new species is distinguished from its congeners by shape of rostral region, cuspides, dorsosejugal region with long dorsophragmatic apophysis, humeral region, carina on trochantera III and IV, and solenidia of legs.

Figures

FIGURE 15: A – Left of lyrifissure im region of Tectocepheus velatus velatus (Michael, 1880) (NSMT-Ac 13633); B-G: Tectocepheus acutus sp. nov. B – Dorsal view; C – Prodorsum; D – Solenidial region on left tarsus I and tibia I; E – Solenidial region on left genu I;

FIGURE 16: Tectocepheus acutus n.sp.: Ventral view (Paratype NSMT-Ac 13631).