Trichoribates hirauchiae, Maruyama & Shimano & Bayartogtokh, 2016

Maruyama, I., Shimano, S. & Bayartogtokh, B., 2016, Two new species of the genus Trichoribates (Acari: Oribatida: Ceratozetidae) from Central Japan, Acarologia 56 (2), pp. 213-224 : 218-221

Trichoribates hirauchiae n. sp.

[Japanese name: Hirauchi-kobanedani] ( Figures 3-5 )

Diagnosis — Large in size; rostrum with pair of minute lateral dens a nose-like protuberance dorsally; rostral, lamellar and interlamellar setae long, barbed; lamellae narrow, translamella very weakly developed, sometimes absent; lamellar cusps with distinct lateral dens, but medial dens minute or absent; sensilli short, with clavate head, its surface roughened; tutoria long and broad, with five or six dentations at the distal end; 10 pairs of short, thin notogastral setae finely barbed; porose areas round to elongate oval, Aa largest, A 1 smallest, located very close to A 2, sometimes A 1 joined to A 2; epimeral and ano-genital setae minutely barbed.

Measurements — Body length: 605 – 668 (629) µm; width: 438 – 516 (471) µm (n=7).

Integument — Body color yellowish brown to reddish brown. With thick cerotegument, roughened by minute granules. Faintly microtuberculate on cuticle of prodorsum, notogaster, ventral plate and leg segments.

Prodorsum — Rostrum rounded, with pair of minute lateral dens and nose-like protuberance dorsally ( Figure 4B ). Rostral setae 93 – 97 µm long, curved inward, conspicuously barbed; distance between alveoli of rostral setae 124 µm. Lamellae narrow, 128 – 134 µm long, gradually converging anteriorly, about 8/ 10 in length of prodorsum ( Figure 4A ); distance between alveoli of lamellar setae 48 µm long. Translamella very weakly developed, sometimes absent. Length of lamellar cusps 44 – 47 µm long, with distinct lateral dens of 9 – 12 µm long; inner dens minute or absent ( Figure 4D ). Lamellar setae barbed, 96 – 102 µm long; interlamellar setae barbed, 177 – 179 µm long, extending beyond tip of rostrum, their insertion pores concealed under anterior marginal part of notogaster ( Figure 4E ). Relative length of prodorsal setae: ro: le: in = 0.96: 1.0: 1.8, respectively. Sensilli 68 – 70 µm long, with clavate head slightly bending medialy, its surface roughened. Bothridia completely concealed under anterior marginal part of notogaster. Tutoria long and broad, extending beyond alveoli of rostral setae, finely striated along its dorsal edge, with five or six dentations at the distal end ( Figure 3C ).

Notogaster — Longer than wide, anterior margin broadly rounded; lenticulus poorly developed. Pteromorphs well developed, curved ventrally, with rounded margin ( Figure 4E ). Ten pairs of notogastral setae short, weakly barbed; relative length of the setae: c> la> lm, p 1> p 2> p 3, h 3 ≥ h 1> h 2. Relative mutual distance between pairs of setae: p 3 - p 3> la-la> h 3 - h 3> c-c> h 2 - h 2> lm-lm> lp-lp ≈ p 2 - p 2> h 1 - h 1> p 1 - p 1. Among four pairs of porose areas, Aa largest, oval; A 1 smallest, round to oval, located very close to A 2; A 2 and A 3 of medium size, elliptical or oval ( Figure 4C ); sometimes A 1 joined to A 2, but in one specimen A 2 divided into two parts. Lyrifissures im situated at level midway between setae la and lp. Openings of opisthosomal glands (gla) located anterior to setae h 3.

Gnathosoma — Subcapitular mentum nearly as long as wide, without noticeable microtubercles. Hypostomal setae m, a and h minutely barbed ( Figure 4F ). Chelicerae with strongly sclerotized blunt teeth; setae cha and chb barbed. Palps typical for family, palpal setation 0-2-1-3-10 including both ventral setae and solenidion ω of tarsi.

Epimeral region — Apodemes apo.2, apo.sj and apo.3 well developed, dark-colored. Epimeral setae short, thin, finely barbed, setal formula: 3-1-3- 3. Custodia reaching anterior margin of pedotecta II; discidia well developed, conspicuously projecting laterally ( Figure 4F ). Pedotecta I large, surface smooth, without striation.

Ano-genital region — Anal and genital plates smooth; both genital and anal openings slightly wider than long ( Figure 4F ). Genital and aggenital setae thin, minutely barbed; relative length of distance between pairs of setae: g 4 - g 4> g 5 - g 5> g 3 - g 3> g 6 - g 6> g 2 - g 2 ≈ g 1 - g 1. Anal and adanal setae thin, minutely barbed; relative length of their mutual distance an 2 - an 2> an 1 - an 1. Setae ad 3 situated in paranal position, at level posterior to anal setae an 2. Adanal lyrifissure (iad) aligned obliquely, situated slightly anterior to level of setae an 2, adjacent to anterolateral margins of anal aperture.

Legs — Median claw thicker than lateral claws ( Figure 5 ). Solenidia ω 1 and ω 2 on tarsi I subequal in length; solenidia Φ 1 on tibiae I nearly three times as long as Φ 2; solenidia σ on genua I slightly longer than that on genua II. Solenidia ω 1 and ω 2 on tarsi II subequal in length. Leg II shortest and leg IV longest. Femora I–IV, trochanters IV with ventral blade. Formula of leg setation (including famulus): I (1-5-3-4-20); II (1-5-3-4-15); III (2-2-1-3-15); IV (1-2- 2-3-12); formula of solenidia: I (1-2-2), II (1-1-2), III (1-1-0), IV (0-1-0).

Type-series — Holotype ( NSMT –Ac 11518, male): Near summit of Mt. Naeba , 36°50’28"N, 138°41’15"E, 2110 m a.s.l., Sakae-mura in Shimominauchi-gun, Nagano Prefecture; from litter and soil of a wetland dominated by Veratrum stamineum Maxim , 26 August 1996, collected by I. Maruyama. Two paratypes ( NSMT –Ac 11519–11520, males): the same data as holotype. The holotype and paratypes (mounted on slides) will be deposited in the National Science Museum, Tokyo, Japan. Additional non-type specimens (three females and four males) from the same locality as holotype are preserved in the collection of S. Shimano.

Remarks — Trichoribates hirauchiae sp. nov. is similar to T. rausensis described by Aoki (1982) from Hokkaido, Ishikawa, Yamanashi and Nagano Prefectures (northern and central Japan) in the narrow lamellae, the weakly-developed translamella, and the clavate sensilli. However, T. hirauchiae sp. nov. is readily distinguishable from T. rausensis by the different structure of porose areas A 1 and A 2 (A 1 is larger than A 2 in T. rausensis ); the much larger body size (body length: 524 – 564 µm width: 332 – 420 µm in T. rausensis ); the far longer interlamellar and rostral setae, extending beyond the rostral tip (setae in and ro of T. rausensis not reaching tip of rostrum); the lamellae gradually converging anteriorly (lamellae of T. rausensis nearly parallel to each other).

Etymology — This species is named in memory of our colleague, late acarologist, Mrs. Yoshiko Hi- rauchi for her generous contribution to the knowledge of oribatid mites of the Toyama Prefecture, Central Japan.

Figures

FIGURE 3: Variation of tutoria in two species of Trichoribates: A – Left and right tutoria of Trichoribates aokii n. sp.; B – Variation of tutorial distal dentations of Trichoribates aokii n. sp.; C – Left and right tutoria of Trichoribates hirauchiae n. sp.

FIGURE 4: Trichoribates hirauchiae n. sp.: A – prodorsum; B – rostrum; C – notogastral porose areas; D – variation of lamellar cusps; E – dorsal aspect of body, legs omitted; F – ventral aspect of body, legs omitted. B-D and E, F to same scale.

FIGURE 5: Trichoribates hirauchiae n. sp.: A – leg I (right, antiaxial aspect); B – leg II (right, antiaxial aspect); C – leg III (right, paraxial aspect, tibia and genu slightly twisted); D – leg IV (right, paraxial aspect).