Messoracarus schwendingeri, Kontschán, Jenő & Seeman, Owen D., 2012

Kontschán, Jenő & Seeman, Owen D., 2012, A new species of Messoracarus (Acari: Mesostigmata: Aenictequoidea: Messoracaridae) from Laos, Zootaxa 3527, pp. 55-62 : 56-61

Messoracarus schwendingeri sp. nov.

( Figs 1–15 )

Material examined. Holotype. Female, Laos, LT-10/12, Oudomxai Prov., ca. 3 km E of Tad Lak 11, SE of Oudomxai (= Muang Xai) city, 2036’20”N, 10201’16”E, 1020 m, primary forest, 18 September 2010, P. Schwendinger coll. (in NHMG). Paratype. One male in QM, locality and date same as holotype. One male, Laos, LT-10/14, Oudomxai Prov., trail to Tad Nam Kad, E of Oudomxai (= Muang Xai) city, 2041’45”N, 10206’45”E, 900 m, primary forest, 19 September 2010, P. Schwendinger coll. ( NHMG).

Description. Female ( Figs 1–7 ). Idiosoma length 510 µm, width at level of coxae IV 560 µm, body margin straight posteriorly.

Dorsal idiosoma ( Figs 1–3 ). Dorsum with single dorsal shield, surrounded by marginal shield, with line of fusion between shields; dorsal shield slightly hypertrichous, setae short, simple (26–33 µm) ( Fig. 1 ). Marginal shield hypertrichous, setae short and needle-like (19–20 µm), or wide and robust (47–48 µm) ( Fig. 3 ). Dorsal shield mostly smooth, excepting very fine reticulation near margins ( Figs 1–3 ). Several sigilla present on anterolateral area of dorsal shield ( Fig. 2 ). Surface of marginal shield covered by linear sculptural pattern.

Ventral idiosoma ( Figs 4–7 ). Sclerotisation extensive, forming large, contiguous shields, with reticulate pattern, and separated by narrow strips of membranous cuticle ( Fig. 4 ). Tritosternal base narrow, laciniae fused, marginally and apically serrate (see Fig. 9 , male). Sternal shield fragmented into five plates, all smooth. Paired presternal plates bearing needle-like setae st1 (16–18 µm) and stp1 at posterolateral margins ( Fig. 5 ). Anteromedial sternal fragment subtriangular, without setae. Medial sternal fragment fused laterally to endopodal shield, bearing setae st2 (42–44 µm) and stp 2. Posterior sternal fragment narrow, fused laterally to endopodal shields, extending into genital region medially, bearing one pair of smooth setae (st3), length 23 µm. Endopodal shield smooth and without setae.

Latigynal shields rectangular, with internal surface less expansive than external surface, the line between them differentiated by a thickened line of cuticle (long-dashed line in Fig. 5 ). Latigynal shields with smooth surface, each bearing 5–7 short (5–7 µm) smooth setae and an anteromedial group of pores, their mesal margins parallel. Mesogynal shield obscured but present, apparently fused to ventrianal shield. Internal genitalia not clearly visible ( Fig. 5 ), but with weak vaginal sclerites meeting at a medial porose plate, from which two thick branches extend posteriorly.

Ventrianal shield with numerous short (8–9 µm), needle-like setae and its surface covered by reticulate sculptural pattern ( Fig. 6 ). Anal valves with vestigial euanal setae. Peritrematal shield fused with exopodal, endopodal and metapodal region and with marginal shield at level of coxae II–III ( Fig. 4 ). Peritremes almost straight, extending to level of coxae II, stigmata situated at level of anterior margin of coxae IV. Marginal shield with linear sculptural pattern and bearing short (9–10 µm), needle-like setae. Marginal shield deeply incised posteriorly but not forming separate plate ( Fig. 6 ).

Gnathosoma . Same as male. Gnathotectum rounded, with serrate margin ( Fig. 7 ).

Chelicerae. Not seen clearly, but appear same as male. Legs. Same as male.

Male ( Figs 8–16 ). Idiosoma length 470–480 µm, width at level coxae IV 490–500 µm, body straight posteriorly. Dorsal ornamentation and chaetotaxy same as in female.

Ventral idiosoma ( Figs 8–9 ). Tritosternum same as female ( Fig. 9 ). Sternal shield fragmented anteriorly, with paired presternal plates smooth and bearing needle-like setae st1 (12–13 µm) and anteromedial sternal fragment smooth, subtriangular and without setae; sternoventral shield fused with endopodal shield and bearing seven pairs of smooth setae (9–10 µm) ( Fig. 8 ). Genital shield linguliform, without setae, surface smooth, anteriorly with small round genital valve, basally fused to ventrianal shield, several sigilla present on basal area. Setation and ornamentation of ventrianal shield same as in female.

Gnathosoma ( Figs 10–11 ). Hypostomal setae h1–h4 smooth and long (36–40 µm). Tip of hypostome expanded, with paired membranous flanges. Internal malae with numerous denticles, about as long as corniculi. Paired, tapering medial processes arise above malae and extend beyond their tips. Corniculi lightly sclerotised basally, becoming membranous, with lateral tine and broad denticulate lobes. Palp tibia and tarsus fused, but with partial line of fusion; apotele two-tined. Palp setal formula 2-4-7-22 ( Fig. 11 ). Fixed digit of chelicera bearing niblike cheliceral seta ( Fig. 12 ), developed pilus dentilis, fringe of hairs (in place of teeth), a serrated membranous excrescence; digit terminating in a forked tip; antiaxial surface bearing a membranous lobe with numerous tiny denticles. Movable digit gradually becomes unsclerotised, bearing a hyaline fringed lobe and nine hyaline “teeth, three excrescences (one long and coarsely serrated; one shorter and finely serrated; one very short with few serrations); digit also terminates in a forked tip.

Legs ( Figs 13–16 ). Leg I without pretarsus; legs II–IV with claws slender, weakly formed, and well-developed ambulacrum. All setae on legs fine, weakly barbed to smooth. Leg seta counts (coxa-tarsus): 2-5-10-8-8 -40, 2- 5-9- 8-7-19, 2- 5-7-10-8-19, 1- 5-8-8-7-21. Chaetotaxy as in Figs 13–16 . Tarsus I with two very long setae, three thick blunt setae, and a cluster of three short blunt setae. Coxae II–IV with large ventrodistal denticles. Genu and tibia II–IV with large crescent-shaped slit organs ( Fig. 15 ).

Nymphs and larvae: Unknown.

Host. Unknown.

Etymology. We dedicate the new species to Dr. Peter Schwendinger, who collected these mites.

Figures

FIGURES 1 – 3. Messoracarus schwendingeri sp. nov., female. 1. Dorsal idiosoma; 2. Dorsal shield pattern and setae; 3. Marginal and dorsal setae.

FIGURES 4 – 6. Messoracarus schwendingeri sp. nov., female. 4. Ventral idiosoma; 5. Intercoxal area; 6. Ventrianal area.

FIGURES 7 – 12. Messoracarus schwendingeri sp. nov. 7. Gnathotectum of female. 8. Ventral idiosoma of male; 9. Tritosternum of male; 10. Ventral gnathosoma of male; 11. Palp of male; 12. Antaxial (left) and abaxial (right) view of chelicerae of male.

FIGURES 13 – 16. Messoracarus schwendingeri sp. nov., male. 13. Leg I; 14. Leg II; 15. Leg III, with dorsal view of genu and tibia; 16. Leg IV.