Trhypochthonius nigricans Willmann, 1928

Szywilewska-Szczykutowicz, Anetta & Olszanowski, Ziemowit, 2007, Redescription of C. Willmann’s Holarctic species of the genus Trhypochthonius (Acari: Oribatida: Trhypochthoniidae), Zootaxa 1406, pp. 17-24 : 19-22

Trhypochthonius nigricans Willmann, 1928

( Figs. 8 –31)

Trhypochthonius nigricans: sensu Seniczak and Norton 1994 Trhypochthonius sphagnicola Weigmann, 1997 (n. syn.)

Description. Body length: 500–590 Μm (lectotype: 565 Μm); body width: 270–340 Μm (lectotype: 320 Μm). Colour: dark-brown.

Prodorsum ( Figs. 8 –16, 19–30). Integument porose. Rostrum rounded. All prodorsal setae barbed, thick, blunt apically. Rostral setae 60 Μm, lamellar setae 70 Μm, interlamellar setae 70 Μm long. Sensilli 50Μm long with distal ovate head with indistinct spines in apical part ( Figs. 8 –13, 19–28).

Notogaster ( Figs. 8 , 12, 19, 22, 27). Integument granulated, surface with reticulate sculpture. All notogastral setae barbed, blunt at the tip and not (or only slightly) widened apically. Length of setae (lectotype designated by Weigmann): c1 20 Μm, c3 30 Μm, e1 30 Μm, h1 50Μm. Vestigial alveoli of setae f1 situated anterior to insertions of setae h1 (distance h1–h1 approximately equal to f1–f1).

Ventral region. Anal and genital shields similar in length. Only genital setae ciliate; other ventral setae smooth. 7–9 pairs of genital setae; narrow anal plate with one seta; adanal plate with three setae.

Material examined. Type material, Germany: three slides from C. Willmann’s collection (Zoologische Staattsammlung Munich, Germany):

(1) Lectotype (designated by Weigmann 1997): ZSM 20044057. Slide labelled “ Trhypochthonius nigricans Willm. Det. C. Willmann. B 51 Büchel b. Wasserburg a./ Bodensee, 7.9.27 ”; two specimens. The lectotype is in good condition and could be easily distinguished from the paralectotype with burst notogaster which does not possess sensilli and interlamellar setae.

(2) Paralectotypes: ZSM 20044058. Slide labelled “ Trhypochthonius nigricans Willm. Det. C. Willmann. B. 5.1. Büchel b. Wasserburg a./ Bodensee, 7.9.27 ”; three specimens.

(3) Paralectotypes: ZSM 20044056. Slide labelled “ Trhypochthonius nigricans Willm. Nymph. Det. C. Willmann. B. 5.1 Büchel b. Wasserburg a./ Bodensee, 7.9.27 ”; two specimens.

Slide from G. Weigmann’s collection (Berlin, Germany), labelled: “ T. sphagnicola , syntype ”; one specimen. The specimen is mounted on a permanent slide, is a little distorted, concave, which has caused apparent changes to the outline of the body and the length of setae.

Comparative material: Poland: 23.07.1984, Roztocze Środkowe, Zwierzyniec, Roztoczański Nat. Park, Bukowa Góra Reserve, 310 m a.s.l., pine forest, from soil, leg. M. Sobkowiak [JB – 362]; 30.07.1987; Bory Tucholskie, Śliwice Prov., pine forest, from soil, leg. J. Błoszyk and Z. Olszanowski [JB – 616]; USA: Texas, Nacogdoches Co., Nacogdoches, 8 mi S S. F. Austin Expt. For., 8.VI.1972, pine buttress, upland pine-oak; leg. W. Suter [ FMHD #72-42]; Kentucky, Edmonson Co., Mammoth Cave Natl. Pk., Sloans Crossing, 20.IV.1983, grassy litter nr. Pond, W. Suter [ FMHD #83-39]; Kentucky, Edmonson Co., Mammoth Cave Natl. Pk., 18.III.1972, litter at log, W. Suter [ FMHD #72-1124].

Remarks. The ventral region was described on the basis of the comparative material from Poland; the lectotype and other specimens in C. Willmann’s collection are preserved as permanent slides, which makes precise observation of ventral characters impossible. Wilmann’s (1928) remark concerning a darker colour of the body of T. cladonicolus compared with that of T. tectorum is unfounded in our opinion.

FIGURES 12–18. Trhypochthonius nigricans (specimen from C. Willmann’s collection), paralectotype. (12) Dorsal view; (13) trichobothrium; (14) seta ro; (15) seta le; (16) seta in; (17) seta h1; (18) seta h2. Scale: 12 = 100 µm; 13–18 = 300 µm.

FIGURES 27–31. Trhypochthonius nigricans (= syntype of T. sphagnicolus sensu Weigmann ). (27) Dorsal view; (28) trichobothrium; (29) seta in; (30) seta le; (31) seta c3. Scale: 27 = 80 µm; 28–31 = 300 µm.

Figures

FIGURES 8 – 11. Trhypochthonius nigricans (specimens from C. Willmann’s collection), lectotype (8 – 9) and two paralectotypes (10 – 11). (8) Dorsal view; (9) trichobothrium; (10) trichobothrium; (11) prodorsum, dorso-lateral view. Scale: 8, 11 = 100 µm; 9, 10 = 300 µm.