Arphthicarus baculus, Liu & Wu & Chen, 2014

Liu, Dong, Wu, Donghui & Chen, Jun, 2014, First record of the genus Arphthicarus Niedbała (Acari: Oribatida: Phthiracaridae) from China, with descriptions of two new species, Journal of Natural History (J. Nat. Hist.) 48 (35 - 36), pp. 2199-2206 : 2200-2203

Arphthicarus baculus sp. nov.

( Figure 1 )

Diagnosis

Surface of body covered with large foveolae; sigillar fields of prodorsum and posterior furrows well developed; one pair of lateral carinae present, nearly reaching sinus; sensilla long, narrow, swollen at the end and covered with small spines; interlamellar and notogastral setae long and robust, erect and obtuse distally, densely barbed in distal half; lamellar and rostral setae spiniform, short, rough and semi-erect; exobothridial short and fine; ss> in> ex>ro> le; setae ps 4 situated anterior to the level of setae ad 2; two pairs of lyrifissures ia and im present; h> h–h; setae g 6 situated anteriolateral to g 5; setae ad 2 situated at level of setae an 1; setae ad 3 smooth; ad 1> ad 2> an 1 = an 2> ad 3; setae d on femora I situated near distal end of article.

Material examined

Holotype: adult ( ZMCAS, in alcohol, W-93-20), China: Hunan Province, Yizhang County, Mangshan Mountains, Pingkeng (24°58 ʹ 43.18 ʺ N, 112°51 ʹ 3.50 ʺ E), from litter, 17 March 1991, leg. Fu-Sheng Huang. Paratype: one adult ( ZMCAS, in alcohol, W-93-20), same data as holotype .

Description

Measurements. Holotype: Prodorsum: length 250, width 170, height 90, setae: ss 80, ro 16, le 10, in 72, ex 20; distance between setae: ro–ro 23, in–in 55, le–le 102; notogaster: length 464, width 319, height 290; setae: c 1 70, c 2 67, c 3 66, c p 61, d 1 62, d 2 55, e 1 75, e 2 59, h 1 77, h 2 65, h 3 58, ps 1 73, ps 2 65, ps 3 55, ps 4 50; distance between setae: c 1 – d 1 120, d 1 – e 1 145, e 1 – h 1 115, h 1 – ps 1 95; ventral region: ad 1 75, ad 2 70, ad 3 37, an 1 55, an 2 55; genitoaggenital plate 132 × 115, anoadanal plate 176 × 105. Paratype: Prodorsum: length 240, width 165, height 100; notogaster: length 448, width 305, height 275; genitoaggenital plate 125 × 110, anoadanal plate 188 × 105.

Integument. Colour yellowish to brown. Surface of body covered with large foveolae.

Prodorsum ( Figure 1A–C ). One pair of lateral carinae (ca) present, nearly reaching sinus; sigillar fields distinct, dorsal field narrow, longer than lateral fields; posterior furrows developed; sensilla (ss) long, narrow, swollen at the end and covered with small spines; interlamellar setae (in) bacilliform, long, robust, erect and obtuse distally, densely barbed in distal half; lamellar (le) and rostral (ro) setae spiniform, short, rough and semi-erect; rostral setae much thicker than lamellar setae; exobothridial setae (ex) short and fine; comparative length: ss> in> ex>ro> le.

Notogaster ( Figure 1A ). Fifteen pairs of setae present, moderately long (c 1 <c 1 – d 1), similar shape to interlamellar setae, setae h 1 longest, setae ps 4 thinner and shortest; setae c 1–3 remote from anterior border, setae c 2 more remote than c 1 and c 3; vestigial setae f 1 not observed; two pairs of lyrifissures ia and im present.

Ventral region ( Figure 1D, E ). Setae h of mentum longer than distance between them. Nine pairs of genital setae (g) present, arranged with formula: 6(4 + 2): 3. Anoadanal plates each with five setae (ad and an), pointed distally, setae ad 1 and ad 2 rough, nearly straight, longer and thicker than other setae, setae ad 3 and anal setae slightly thinner and smooth; comparative length: ad 1> ad 2> an 1 = an 2> ad 3.

Legs ( Figure 1F–I ). Setal counts for leg segments (without tarsi): I: 1–4–2(2)–5(1); II: 1–3–2(1)–3(1), III: 2–2–1(1)–2(1), IV: 2–1–1–2(1); setae d on femora I situated near distal end of article; setae a” on tarsi I and setae ft” on tarsi II curved distally; setae a” on tarsi II curved distally; setae s and pv’ on tarsi IV present; setae s on tarsi I and II absent.

Etymology

The new specific name ‘ baculus ’ is from Latin, and refers to the bacilliform shape of the notogastral setae.

Remarks

This new species is similar to Arphthicarus ineptus ( Niedbała, 1984) from India in the presence of two pairs of lyrifissures and similar shape of lamellar, interlamellar and notogastral setae, but can be easily distinguished from the latter species by following characters: in A.baculus sp. nov., surface of body covered with large foveolae; sigillar fields of prodorsum and posterior furrows well developed; lateral carinae much longer, nearly reaching sinus; head of sensilla more inflated in dorsal view and more elongate in lateral view; interlamellar and rostral setae much shorter (in 72, ro 16), ss> in> ex>ro> le; rostral setae thicker and rough, shorter than exobothridial setae (ex 20); notogastral setae much shorter (e.g. c 1 70); setae g 6 situated anteriolateral to g 5; setae ad 2 situated at level of setae an 1; setae ad 3 smooth; setae a” on tarsi I and tarsi II present. In A.ineptus , surface of body covered with small foveolae; sigillar fields of prodorsum and posterior furrows indistinct; lateral carinae short, far from sinus; head of sensilla slightly inflated in dorsal view and shorter in lateral view; interlamellar and rostral setae much longer (in 123, ro 54.2), in> ss> ro>ex> le; rostral setae thin and smooth, much longer than exobothridial setae (ex 25.2); notogastral setae much longer (e.g. c 1 108); setae g 6 situated posteriolateral to g 5; setae ad 2 situated at level between setae an 1 and an 2; setae ad 3 covered with small spines; setae a” on tarsi I and tarsi II absent.

This new species is also similar to Arphthicarus pachetos Niedbała, 2008 from Borneo by the presence of two pairs of lyrifissures, similar shape of sensilla, similar shape and length of interlamellar, lamellar and notogastral setae, but differs by following characters: in A.baculus sp. nov., posterior furrows of prodorsum developed; lateral carinae relatively short, not reaching sinus; dorsal sigillar field narrower than lateral ones; rostral setae much shorter (ro 16) and spiniform; ss> in> ex>ro> le; distance between rostral setae shorter (in–in/ro–ro = 2.39); setae ps 4 situated anterior to the level of setae ad 2; setae h of mentum not vestigial; setae ad 2 not distinctly longer than other setae of anoadanal plates; setae ad 2 situated at level of setae an 1; setae d on femora I situated much anterior to the level of setae v’. In A. pachetos , posterior furrows absent; lateral carinae very long, reaching the end of rostrum; dorsal sigillar field broader than lateral ones; rostral setae longer (ro 53) and setiform; in> ss> ro>le> ex; distance between rostral setae longer (in–in/ro–ro <1.5); setae ps 4 situated at the level of setae ad 2; setae h of mentum vestigial; setae ad 2 distinctly longer than other setae of anoadanal plates; setae ad 2 situated at level between setae an 1 and an 2; setae d on femora I situated at the level of setae v’.

Figures

Figure 1. Arphthicarus baculus sp. nov. (A) Lateral view of body (legs removed); (B) prodorsum, dorsal view; (C) sensillum, dorsal view; (D) left side of ventral plate; (E) mentum of infracapitulum; (F–I) trochanter, femur, genu and tibia: (F) leg I; (G) leg II; (H) leg III; (I) leg IV. Scale bars: 100 μm (A, D, F–I), 50 μm (B, C, E).