Damaeidae Berlese, 1896

Nakamura, K., Nakamura, Y. - N. & Fujikawa, T., 2014, Oribatid Fauna (Acari, Oribatida) From A Cave In South Nippon (Japan), With A Description Of A New Species, Acarologia 54 (3), pp. 249-269 : 256-257

Damaeidae Berlese, 1896 Spatiodamaeus sp.

( Figs. 5 – 9 )

In the present paper, one specimen was described as Spatiodamaeus sp. Although it may prove in the future being representatives of new species, it was not designed as new species in the present paper because only a single, damaged specimen was found.

Diagnosis — Body length 536 µm; width 429 µm. Rostral anterior margin widely rounded. Prodorsal setae ro, le, in, ss, ex, long, minutely barbed throughout length. Notogaster bearing exuviae with polygonal structure. Spinae adnatae acute. Of 11 pairs of notogastral setae, eight pairs smooth, hypertrophied, widened, blade-like; p 1-3 setae long, setiform, minutely barbed throughout length Genito-anal setal formula: 6-1-2-3. Ventral tubercle (Va) with long sharply pointed apex, bending to lateral side. Lyrifissures iad aligned obliquely. Epimeral setal formula: 3-1-3-3.

Material examined — One adult female (NSMT- Ac 13786) from the soil surface at the entrance of Kumaso cave. The specimen is deposited in the National Museum of Nature and Science, Tokyo .

Measurements and body appearance — Body length 536 µm; width 429 µm. Body colour of live mite dark brown; body surface smooth. Notogaster bearing concentrically arranged exuviae with polygonal structure ( Fig. 5 ).

Prodorsum — Rostral anterior margin widely rounded. Rostral setae (ro) (ca. 129 µm) inserted just behind the border of the underlying rostrophragma (Fig. 3). Lamellar setae (le) (Right-left: 157-141 µm) reaching anterior rostral margin. Interlamellar setae (in) (159-150 µm) reaching rostral cavity. Sensilla (ss) (ca. 195 µm) long spiniform, minutely barbed throughout length. Exobothridial setae (ex) (61-77 µm) inserted at lateral side of bothridia. Setae ro, le, in and ex long setiform, minutely barbed throughout length. Bothridia opening latero-dorsally with large funnel-like extension of palmate laminated appearance.

Notogaster — concentrically bearing arranged exuviae with polygonal structure ( Fig. 5 ). Spinae adnatae acute (29 µm). Of 11 pairs of notogastral setae; eight pairs (c 1-2, la, lm, lp, h 1-3) (68-111 µm) smooth, hypertrophied, widened, blade-like ( Fig. 6 ), arranged in two longitudinal rows; p 1-3 -setae (86- 152 µm) long setiform, minutely barbed throughout length; p 3 longest; lp shortest. Lyrifissures ia, ih, ips aligned parallel to notogastral outline, located lateral to setae c 2, lp and h 3, respectively; im, ip obliquely aligned, lateral to setae lm and p 3, respectively. Opisthonotal gland opening (gla) situated laterally between setae lp and h 3.

Ventral region — Ventral tubercles (Va) with long sharply pointed apex, bending laterally ( Fig. 7 ). Genito-anal setal formula: 6-1-2-3; all setae thin, setiform, roughened. Genital setae (30-48 µm) aligned in longitudinal row; g 1 longest. Setae ag (ca. 47 µm) inserting postero-laterally to genital aperture. Setae an 1 (ca. 41 µm) inserted almost at middistance along plate; an 2 (ca. 38 µm) near anterior margin of plate. Setae ad 1 (34-34 µm) near posterolateral corner of anal aperture; ad 2, 3 (ca. 45 µm) in adanal position; ad 3 inserted at level of an 1. Lyrifissures iad oriented obliquely, anterior to ad 3. Genital (107 µm) and anal (96 µm) apertures almost pentagonal in shape; distance between them (18 µm) about one-sixth as long as anal aperture. Sternal ridge and epimeral borders 1-4, sj indistinct. Epimeral setal formula: 3-1-3-3; setae smooth, short, setiform (14- 91 µm); 1b longest; 4a shortest. Subcapitular setae 3 pairs, a (30-43 µm), m (48-43 µm), and h (55-57 µm); setae thin setiform; a, m roughened throughout length; h minutely barbed unilaterally. Cheliceral setae cha (ca. 38 µm) barbed unilaterally, terminating in fine tips; chb (ca. 27 µm) attenuate conspicuously and unilaterally pilose in distal portion ( Fig. 8F ). Pedipalpal setal formula: 0-2-1-3-9[1]; solenidion spiniform ( Fig. 8A ).

Legs — Monodactylous; claw smooth (45-61µm) ( Figs. 8D and E ); claw of leg IV longest; claw of leg II shortest. Setal formula: I (1-6-4-4-19), II (1-5-4-4- 16), III (2-4-4-3-14), IV (1-4-4-3-14). Measurements (µm) of [right-left] segments: I ([39-46]-[248-223]- [?-98]-[?-138]-[?-255]); II ([61-59]-[202-189]-[?-77]-[?- 105]-[191-220]); III ([?-130]-[161-163]-[82-?]-[120-?]- [220-?]); IV ([150-186]-[145-186]-[89-?]-[154-?]-[263- 275]). Setae long, setiform or bacilliform, verrucose throughout length ( Fig. 9 ). On tarsus I, famulus ε (ca. 30 µm) consisting of fine tip and expanded basal portion, situated posteriorly, contiguously between ω 1 (ca. 45 µm) and ω 2 (ca. 27 µm); ω 1, ω 2 terminating in fine tip ( Fig. 8C ). Solenidion ’ 1 (ca. 143 µm) originating from small apophysis on tip of tibia I; ’ 2 (ca. 41 µm) originating from smaller apophyses than that of ’ 1, lateral to ’ 1. On genu I, solenidion σ (ca. 36 µm) terminating in fine tip, shorter than seta d ( Fig. 9A ).

Remarks — Bulanova-Zachvatkina (1957) erected new subgenus Spatiodamaeus , belonging to the genus Damaeus , without original designation for type species, and described three new species, D. (S.) boreus , D. (S.) fageti and D. (S.) subverticillipes as members of the new subgenus. At the same time, she added five known species, Belba glabriseta Willmann, 1930 , Damaeus phalangioides Michael, 1890 , D. tecticola Michael, 1888 , D. tenuipes Michael, 1885 and D. verticillipes Nicolet, 1855 to the new subgenus, of which D. phalangioides was referred to the genus Metabelbella Bulanova-Zachvatkina, 1957 ( Arillo and Subías, 2006), and D. tecticola and D. tenuipes to the genus Epidamaeus Bulanova-Zachvatkina, 1957 ( Luxton, 1989) . Since then, Bulanova-Zachvatkina (1967) elevated Spatiodamaeus to generic status, designating D. verticillipes Nicolet, 1855 as the type. Norton (1977) reviewed it as a subgenus, while Balogh (1972), Balogh and Balogh (1992), Subías (2004) and Weigmann (2006) treated it as a genus. After eight species were listed as members of the genus Spatiodamaeus by Subías (2004), one species was added ( Xie et al., 2012). D. (S.) verticillipes is microphytophagous ( Schuster, 1956) and diplodiploid ( Norton, 1993). No member of this genus has been recorded from Japan to date. The present specimen was distinguished from congeners by (1) small body size (length 536 µm, width 429 µm); (2) spinae adnatae acute, (3) 11 pairs of notogastral setae, p 1-3 setae long setiform, minutely barbed throughout length, and the other setae smooth hypertrophied, widened, blade-like, and (4) ventral tubercle (Va) with long sharply pointed apex, bending to lateral side.

Figures

FIGURE 5: Spatiodamaeus sp. (photo by Nakamura Y.): A – Exuvial scalps. B – Adult specimen.

FIGURE 6: Spatiodamaeus sp.: Dorsolateral view, legs removed (NSMT-Ac 13786).

FIGURE 7: Spatiodamaeus sp.: Ventrolateral view, legs and pedipalps removed (NSMT-Ac, 13786).

FIGURE 8: Spatiodamaeus sp. (NSMT-Ac 13786): A – Left pedipalp; B – Right seta c1; C – Right tarsus I; D – Claw and distal setae of left leg I; E – Claw and distal setae of left leg IV; F – Left chelicera.

FIGURE 9: Spatiodamaeus sp. (NSMT-Ac 13786): A – Right tibia I and genu I; B – Right tibia II and genu II; C – Left tibia III and genu III; D – Left tibia IV; E – Left genu IV.