Pergalumna amamiensis Aoki, 1984

Hagino, Wataru & Shimano, Satoshi, 2019, Supplementary descriptions of Pergalumna amamiensis Aoki, 1984 (Acariformes Galumnoidea) from Ryukyu Islands, Zootaxa 4647 (1), pp. 378-384 : 379-383

Pergalumna amamiensis Aoki, 1984

pp. 145–146, Fig. 24

( Figs. 1–4 )

Measurements. Body length and width: 519–570 (av. 543) × 363–410 (av. 392) μm (n = 7). Male specimens: 519–570 (av. 540) × 363–390 (av. 374) μm (n = 3). Female specimens: 523–561 (av. 540) × 369–410 (av. 391) μm (n = 4).

Integument. ( Figs. 1 , 2 , 3E, 3F, 3G ) Body color brown to light brown. Whole body surface microfoveolate. Surface of pteromorph ornamented with several types of pattern; conspicuous granules in proximal part, other part ornamented with dense wrinkles as in Fig. 2B (specimens from Amami-Ohshima Island), conspicuous granules in proximal part, other part smooth as Fig. 2C (specimens from Ishigaki Island), dense wrinkles in middle part, other part smooth as in Fig. 2D (specimens from Okinawa Island). Prodorsum, subcapitulum, genital plates and anal plates with fine granules. Genital plates with conspicuous linear structure in central part as in Fig. 3F .

Prodorsum. ( Figs. 1A , 2A , 3B ) Rostrum sharply pointed, with minute spines on either side of tip. Lamellar (L) and sublamellar (S) lines distinct, parallel, curving backwards. Lateral structure N well visible, connected with basal parts of S line. Rostral seta (ro) (approx. 78 μm) setiform, sparsely barbed. Lamellar seta (le) (approx. 103 μm) smooth, setiform, inserted anteriorly from line L. Interlamellar seta (in) (approx. 153 μm) thin, smooth, setiform, hardly visible. Sensillus (ss) (approx. 129 μm) with long stalk, sparsely covered by minute barbs. Exobothridial seta and alveoli absent. Dorsosejugal porose area (Ad) oval, located lateroposterior to seta in.

Notogaster. ( Figs 1A , 2 , 3A ) Anterior notogastral margin well developed. Dorsophragmata (D) near anterior notogastral margin. Ten pairs of notogastral alveoli present. Four pairs of porose areas present: Aa (diameter 33 × 62 μm) bulbous, larger than others, A1 (diameter 20 × 21 μm) circular, smaller than others, A2, and A3 (diameter 20 × 29 μm) almost same in size. Surface of porose area finely dotted. Five pairs of lyrifissures (ia, im, ih, ip, and ips) present; im anterior to setae lp, ip anterior to setae p 1. Opitsthonotal gland opening (gla) located anterior to A2. Median pore (mp) present, represented by single pore.

Gnathosoma. ( Figs. 1B , 3C, 3 D­, 3E) Subcapitulum size: 109–120 × 113–118 μm. Three pairs of subcapitular setae setiform, smooth. Setae h (approx. 15 μm) longer than setae a (approx. 10 μm), setae m shortest (approx. 8 μm) and thinnest. Length of palp: 176–185 μm. Axillary saccule (sac) not observed. Length of chelicera: 150–162 μm. Two cheliceral setae setiform, barbed, cha (approx. 59 μm) longer than chb (approx. 33 μm). Trägårdh’s organ (Tg) long, elongate triangular.

Epimeral and podosomal region. ( Figs 1B , 2A ) Pedotectum I (Pd I) broadly rounded, pedotectum II (Pd II) elongated with round tip. Discidium (dis) triangular. Circumpedal carina (cp) thin, interrupted in level 4c. Setal formula of epimera: 1–0–3–2. Genital plate with six pairs of thin, short, smooth genital setae almost equal in size (approx. 8 μm); g 1, g 2, and g 3 inserted on anterior margin of g 4, g 5, and g 6 shorter than the previous ones, arranged longitudinally. A pair of aggenital setae ag (approx. 6 μm) in posterior region of genital plates.

Anogenital region. ( Figs 1B , 3F, 3G ) Two pairs of anal setae an 1 and an 2 (approx. 8 μm) thin, smooth. Three pairs of adanal setae; ad 1 and ad 2 (approx. 8 μm) posterior to anal plates, ad 3 (approx. 8 μm) situated on paraanal po- sition, anterior to iad. Adanal lyrifissure iad situated parallelly to anal aperture. Posterior porose area (Ap) unpaired, large (approx. 12 × 29 μm), oval, posterior to anal plate.

Legs. (Figs. 14B, Table. 1 ) All legs tridactylous, median claw distinctly thicker than laterals, all claws smooth. Morphology of leg segments, setae and solenidia generally typical for species of Pergalumna and other members of Galumnidae ( Engelbrecht 1972, Ermilov & Mansurov 2017). Porose area on all femora and trochanters III, IV, difficult to observe. Leg setation (Tr- Fe-Ge-Ti-Ta) including famulus: leg I (1-4-3-4-20); II (1-4-3-4-15); III (1-2- 1-3-15); IV (1-2-2-3-12). Solenidiotaxy (Ge-Ti-Ta): I (1-2-2); II (1-1-2); III (1-1-0); IV (0-1-0). Homology of setae and solenidia indicated in Table 1 . Famulus of tarsus I inserted anterior to solenidion ω 1.

Remarks. Based on the supplementary description of P. amamiensis from Ishigaki Island and known literature data ( Aoki, 1984), we propose the following diagnostic morphological traits for this species: body size 519–570 × 363–410 μm; surface of pteromorph ornamented with conspicuous granules in proximal part, other part ornamented with dense wrinkles; prodorsum, subcapitulum, genital plates and anal plates with fine granules; genital plates with conspicuous linear structure in central part; rostrum sharply pointed, with minute spines on either side of a tip; sensillus (ss) with long stalk, sparsely covered by minute barbs; porose area Aa bulbous in shape; A1, A2, and A3 circular, A1 smaller than others, A2, and A3 almost same in size; median pore (mp) present, represented by single pore. Of the above, the pointed rostral tip, the surface of subcapitulum, and the pattern of pteromorph surface were not described in the past, and are herein described for the first time.

Material examined. Seven specimens (three males and four females) were collected from soil and litter of natural broad leaf tree at the type locality on the western part just under summit, Mt Yuwan, Amami-Ohshima Island, Kagoshima Prefecture, approximately 690 m a.s.l., 28th August, 2003 by Satoshi Shimano. One additional specimen (female) was collected from soil and litter of the foot of Mt. Omoto, secondary forest occupied by evergreen broad-leaved trees ( Syzygium buxifolium Hook. et Arn. , Ligustrum japonicum Thunb. , and Terenna gracilipes Ohwi. ), Ishigaki Island, Okinawa Prefecture, 195 m a.s.l., 5th of October, 1978 by Jun-ichi Aoki. One additional specimen (female) was collected from soil and litter from US Marine Corps base in northern part of St. TA 6 (detail date and sampling sites not reported), Okinawa Island, Okinawa Prefecture in 1997 by Jun-ichi Aoki ( Aoki 1998). PA01–09 were given as specimen numbers; PA01–07 for specimens from Amami-Ohshima Island were stored in 99.5% ethanol, PA08 for the specimen from Ishigaki Islands which was dissected and mounted on a slide, PA09 for the specimen from Okinawa Island. PA01, PA08, and PA09 will be deposited in the National Museum of Nature and Science, Tsukuba, Japan.

Distribution. This species was formerly only known from Amami-Ohshima Island in Southwestern Japan ( Aoki 2009) but the present study demonstrated its additionaly presence on Ishigaki Island, and Okinawa Island. This species inhabits the soil and litter of natural broad-leaved forest in the mountain area in Amami-Ohshima Island, and the mountain area in Ishigaki Island. Although the detailed habitat of the record on the US marine corps area in northern Okinawa Island is unknown, the collecting point is situated somewhere in deep mountain area of Kunigami Village or Higashi Village. From the above observations, this species is expected to be found in a relatively wide habitat range in Ryukyu Islands, especially in rich natural forests of evergreen broad-leaved trees in the mountainous areas.

Figures

FIGURE 1. Adult Pergalumna amamiensis. A—dorsal view, B—ventral view (legs not shown). Scale bar 100 μm. Specimens number PA08.

FIGURE 2. Adult Pergalumna amamiensis. A—opisthosoma, lateral view (specimens number PA08), B—pteromorph, dorsal view (specimens number PA01, Amami-Ohshima Island), C—pteromorph, dorsal view (specimens number PA08, Ishigaki Island), D­—pteromorph, dorsal view (specimens number PA09, Okinawa Island). Scale bar 100 μm.

FIGURE 3. Adult Pergalumna amamiensis. A—notogaster, posterior view, B—setae on prodorsum, C—chelicera, right, antiaxial view, D—palp, left, antiaxial view, E—subcapitulum, ventral view, F—genital plates, ventral view, G—anal plates, ventral view. Scale bar (A) 100 μm, (B, C, D­, E, F, G) 50 μm. Specimen number PA08.

FIGURE 4. Legs of adult Pergalumna amamiensis. A—leg I, left, antiaxial view, without trochanter, B—leg II, left, antiaxial view, without trochanter, C—leg III, left, antiaxial view, without trochanter, D—leg IV, left, antiaxial view, without trochanter. Scale bar 100 μm. Specimens number PA08.

Tables

TABLE 1. Leg setation of adult Pergalumna amamiensis. Roman letters refer to normal setae (ε to famulus), Greek letters to solenidia. Single prime (') marks setae on anterior and double prime (") setae on posterior face of the given leg segment. Parentheses refer to a pair of setae. Specimen number PA08.

Leg	Trochanter	Femur	Genu	Tibia	Tarsus
I	v’	d, (l), bv’’	(l), v’, σ	(l), (v), φ 1, φ 2	(ft), (tc), (it), (p), (u), (a), s, (pv), v′, (pl), l′′, ε, ω 1, ω 2
II	v’	d, (l), bv’’	(l), v’, σ	(l), (v), φ	(ft), (tc), (it), (p), (u), (a), s, (pv), ω 1, ω 2
III	v’	d, ev’	l’, σ	l’, (v), φ	(ft), (tc), (it), (p), (u), (a), s, (pv)
IV	v’	d, ev ’	d, l’	l’, (v), φ	ft′′, (tc), (p), (u), (a), s, (pv)