Austrophthiracarus bacilliformis, Liu, 2020

Liu, Dong, 2020, Contribution to the knowledge of the ptyctimous mite genus Austrophthiracarus (Acari, Oribatida, Steganacaridae) with descriptions of two new species from China, Zootaxa 4786 (1), pp. 138-144 : 141-143

Austrophthiracarus bacilliformis sp. nov.

( Figs 2 A–F)

Diagnosis. Surface of body densely punctate; median crista and posterior furrows of prodorsum absent; lateral ca- rinae reaching sinus; dorsal sigillar field narrow, longer than laterals; sensilli rough and bacilliform; interlamellar setae procumbent, thicker than lamellar and rostral setae; exobothridial setae vestigial; 16 pairs of notogastral setae of medium length and three pairs of lyrifissures ia, im and ih present; one additional setae present in ps series; ves- tigial setae f 1 anterior to setae h 1; formula of genital setae 6(4+2): 3; setae g 6 situated at level of setae g 5; ano-adanal plates each with five setae, setae ad 3 thinnest and shortest; h> h–h; setae d situated in the middle of femora I, at level of setae v’’.

Description. Measurements. Holotype: Prodorsum: length 255, width 200, height 102; setae: ss 45, ro 25, le 20, in 50; notogaster: length 515, width 375, height 345; setae: c 1 90, cp 55, d 1 85, e 1 80, h 1 85, h 3 50, ps 1 82, ps 4 30; ventral region: ad 1 60, ad 2 75, ad 3 25, an 1 45, an 2 45; genito-aggenital plate 150×115, ano-adanal plate 195×130. Paratypes: Prodorsum: length 270–285, width 205–220, height 105–115; notogaster: length 530–550, width 395– 405, height 365–385.

Integument. Colour light brown. Surface of body densely punctate.

Prodorsum ( Figs 2 A–B). Median crista, posterior furrows absent; lateral carinae reaching sinus; sigillar fields distinct, dorsal region narrow, longer than lateral regions; sensilli (ss) rough along its entire length and bacilliform, almost equal in thickness throughout length; interlamellar setae (in) procumbent, rough and moderately thick; la- mellar setae (le) short and fine; rostral setae (ro) slightly thicker and longer than lamellar setae, but much thinner than interlamellar setae; exobothridial setae (ex) vestigial; comparative length: in> ss> ro> le; in / le =2.5, ro / le ≈1.3; mutual distance of setae: in–in / ro–ro ≈2.4.

Notogaster ( Fig. 2A ). 16 pairs of setae with medium size (c 1 / c 1 – d 1 ≈0.7), rough, nearly equally long and thick, except setae cp, h 3, ps 3 and ps 4 thinner and shorter; setae c 2 slightly far from anterior border than setae c 1 and c 3; one additional setae (ps 2 ’) present with distribution as depicted in Fig. 2A ; vestigial setae f 1 positioned anterior to setae h 1, vestigial setae f 2 present; three pairs of lyrifissures ia, im and ih present.

Ventral region ( Figs 2A , C–D). Setae h of mentum longer than distance between them. Nine pairs of genital setae (g) arranged in two rows with formula: 6(4+2): 3; setae g 6 situated between level of setae g 5; ano-adanal plates each with five rough setae; setae ad 2 longest and thicker; setae ad 1 intermediate length; setae ad 3 shortest and thinnest; comparative length: ad 2> ad 1>an 1 = an 2>ad 3.

Legs ( Figs 2 E–F). Chaetotaxy of legs complete; setal counts for leg segments: I: 1-4-2(2)-5(1)-19(3); II: 1-3- 2(1)-3(1)-12(2), III: 2-2-1(1)-2(1)-10, IV: 2-1-1-2(1)-10; setae d on femora I inserted at level of setae v’’; setae a’’ on tarsi I, and setae ft’’ and a’’ on tarsi II curved distally; setae s and pv’ on tarsi IV present; setae s on tarsi I and II present.

Material examined. Holotype: 1 adult ( NIGA, in alcohol), China: Heilongjiang Province, Jiamusi, Fujin County, Erlongshan , from forest litter under Quercus mongolica , 13 Aug. 2010, leg. Dong Liu, Donghui Wu, Xiaoqiang Yuan and Yabing Yuan. Paratypes: 3 adults ( NIGA, in alcohol), same data as holotype .

Etymology. The new specific name “ bacilliformis ” refers to the shape of sensillus.

Remarks. This new species is similar to Austrophthiracarus filiformis Liu & Chen, 2014 and Austrophthiracarus setiformis Liu, 2017 in having 16 pairs of notogastral setae, similar shape of rostral and notogastral setae and sigillar field, but can be distinguished by following features: (1) sensilli bacilliform, nearly equally thick in whole length (versus setiform and tapering distally in A. filiformis and A. setiformis ); (2) prodorsal lateral carinae present (versus absent in A. setiformis ); (3) interlamellar setae thick and long (versus fine and much shorter); (4) lamellar short and fine (versus long and thick in A. setiformis ); (5) exobothridial setae vestigial (versus not vestigial in A. filiformis ); (6) one additional setae present in ps series (versus in h series); (7) three pairs of lyrifissures ia, im and ih present (versus four pairs of lyrifissures ia, im, ih and ips in A. filiformis ; two pairs of lyrifissures ia and im in A. setiformis ); (8) vestigial setae f 1 anterior to setae h 1 (versus posterior); (9) formula of genital setae 6(4+2): 3 (ver- sus 7(4+3): 2 in A. setiformis ); (10) setae g 6 situated at level of setae g 5 (versus at level of setae g 4 in A. filiformis ; between level of setae g 4 and g 5 in A. setiformis ); (11) setae ad 2 three times longer than setae ad 3 (versus shorter than setae ad 3 in A. filiformis ); (12) mentum setae h> h–h (versus h <h–h in A. filiformis ); (13) setae d situated in the middle of femora I (versus near distal end of article in A. filiformis ).

This new species is also similar to Austrophthiracarus inusitatus ( Niedbała, 1983) and Austrophthiracarus jumbongiensis Niedbała, 2002 ( Kaczmarek & Niedbała, 2002) in having similar shape of interlamellar setae, and similar arrangement of setae h and ps, but can be easily differed by: (1) sensilli bacilliform, nearly equally thick in whole length (versus setiform and pointed distally in A. inusitatus and A. jumbongiensis ); (2) lamellar and rostral setae short and fine (versus robust and rough in A. inusitatus ; flexible in A. jumbongiensis ); (3) exobothridial setae vestigial (versus not vestigial); (4) one pair of lateral carinae present (versus absent in A. jumbongiensis ); (5) one additional setae present in ps series (versus in h series); (6) vestigial setae f 1 anterior to setae h 1 (versus posterior); (7) three pairs of lyrifissures ia, im and ih present (versus two pairs of lyrifissures ia and im in A. inusitatus ; three pairs of lyrifissures ia, im and ips in A. jumbongiensis ); (8) setae of row c rough and robust (versus smooth and flexible in A. jumbongiensis ); (9) setae ad 2 three times longer than setae ad 3 (versus less two times longer than ad 3); (10) setae g 6 situated at level of setae g 5 (versus between level of setae g 4 and g 5); (11) setae g 6, g 7, g 8 and g 9 similar in length (versus setae g 9 longer than others); (12) setae d situated in the middle of femora I (versus near distal end of article in A. jumbongiensis ).

Figures

FIGURE 2. Austrophthiracarus bacilliformis sp. nov.: A, lateral view of body (legs removed); B, prodorsum, dorsal view; C, left side of ventral plate; D, mentum of subcapitulum, palpi removed; E, femur I; F, tibia IV. Scale bars: A–D=100 μm; E–F=50 μm.