Dinychus chilensis, Kontschán, Jenő & Ripka, Géza, 2016

Kontschán, Jenő & Ripka, Géza, 2016, New species of Dinychus Kramer, 1886 from fragments of the former Gondwanaland (Acari: Uropodina: Dinychidae), Zootaxa 4138 (2), pp. 363-372 : 366-368

Dinychus chilensis sp. nov.

( Figs 10–25 )

Material examined. Holotype. Female. Chile, Petrohue, 28-30 January 1979, M. & Mme Alain de Chambbrier coll. Paratypes: two females, two males, three deutonymphs, same data as holotype. Three females and three males. Chile, Puyehue, Aquas Calientes, 2-5 February 1979, M. & Mme Alain de Chambbrier coll.

Description. Female. Length of idiosoma 685–720 µm, width 330–360 µm (n=6). Shape oblong, posterior margin rounded, colour reddish brown.

Dorsal idiosoma ( Fig. 10 ). Marginal and dorsal shields fused anteriorly. Dorsal and marginal shields bearing smooth and needle-like setae (ca 21–24 µm long). Caudocentral area of dorsal shield elevated above neighbouring areas. Dorsal shield covered by oval pits and bearing poroid-like organs on elevated area. Surface of marginal shield with reticulate sculptural pattern.

Ventral idiosoma ( Fig. 11 ). Majority of surface of sternal shield smooth, only some oval pits situated around St4. A strongly sclerotised U-shaped area placed anterior to genital shield. All sternal setae smooth, needle-like and short (ca 15–17 µm), St1 situated close to anterior margin of sternal shield, St2 on strongly sclerotised area, at level of central area of coxae II, St3 at level of anterior margin of coxae III, St4 at level of anterior margin of coxae IV. Ventral shield with oval and irregular pits. Six pairs of ventral setae similar in shape and length to sternal setae, smooth. Setae ad1 short (ca 8–9 µm) and needle-like, setae ad2 and pa similar in shape and length to ventral setae.

Stigmata situated close to coxae III. Prestigmatid part of peritremes with a hook-like apical end and a U-shaped central section, poststigmatid part long and posteriorly hook-shaped ( Fig. 12 ). Genital shield long, quadrangular, without apical process, apical margin of genital shield smooth. Surface of genital shield without sculptural pattern. Pedofossae absent. Base of tritosternum narrow, vase-like, tritosternal laciniae subdivided into two bulbiform central and two smooth, needle-like lateral branches ( Fig. 13 ).

Gnathosoma ( Fig. 13 ). Corniculi horn-like, internal malae smooth, apically bifurcate and longer than corniculi. Hypostomal setae h1 and h3 long (ca 38–40 µm), h1 smooth, h3 basally serrate, h2 shorter (ca 24–25 µm) but shape as in h3, h4 short (ca 12–13 µm), and marginally serrate. Apical part of epistome marginally pilose. Ventral part of palp trochanter with one smooth and one marginally serrate seta. Chelicerae not clearly visible, fixed digit of longer than movable digit and bears a lateral bulbiform sensory organ, internal sclerotised node present ( Fig. 14 ).

Legs ( Figs 15–18 ). All legs with ambulacral claws and smooth and needle-like setae, tibia II–IV and trochanter I also bearing marginally serrate setae.

Male. Length of idiosoma 650–670 µm, width 350–360 µm (n=5).

Dorsal idiosoma. Ornamentation and chaetotaxy of dorsal shield as for female.

Ventral idiosoma ( Fig. 19 ). Three pairs of sternal setae situated anterior to genital shield, one pair placed at level of central area of genital shield and one close to posterior margin of genital opening. Sternal setae smooth, needle-like and ca 13–15 µm long. Two pairs of poroid-like sensory organs situated between St3 and St4. Surface of sternal shield covered by oval pits. Surface of ventral shield, and shape and size of ventral setae as in female. Genital shield oval and situated between coxae III and IV. Internal malae, corniculi, tritosternum, epistome and chelicera as in female, gnathosomal setae h1 robust, smooth and ca 24–26 µm long, h2, h3 and h4 marginally serrate, h2 ca 28–31 µm, h3 ca 20–21 µm and h4 ca 7–8 µm long ( Fig. 20 ). Ventral surface of femur of leg I bearing a large spine-like process ( Fig. 21 ).

Deutonymph. Length of idiosoma 560–630 µm, width 280–360 µm (n=3).

Dorsal idiosoma ( Fig. 22 ). Dorsal shield pear-shaped and bearing numerous smooth needle-like setae (ca 13–15 µm long), and covered by reticulate sculptural pattern. Numerous smooth and needle-like setae (ca 18–20 µm long) situated on small platelets on margins of dorsal body ( Figs 23–24 ).

Ventral idiosoma ( Fig. 25 ). Sternal shield narrow, posterior part rounded, surface covered by irregular pits. Five pairs of sternal setae smooth, needle-like and ca 16–18 µm long. Metapodal shields fused to endopodal shields, it covered by irregular pits close to posterior margins of coxae II and between coxae III and IV and on metapodal regions, but dotted close to anterior margins. Peritrematal shield free, peritremes with U-shaped central part on prestigmatid part, poststigmatid part absent. Ventroanal shield drop-shaped, covered by irregular pits on anterior area and bearing five pairs of short (ca 14–15 µm) and needle-like setae. Anal opening large, around it with two pairs of short (ca 6–8 µm) and needle-like setae. Lateral part of ventral idiosoma bearing some needle-like (ca 14–15 µm) setae situated on small platelets.

Larva and protonymph unknown.

Etymology. The name of the new species refers to the country where it was collected.

Remarks. Only two other species have an elevated caudocentral area on the dorsal shield. The Tasmanian species Dinychus greensladeae Błoszyk & Halliday, 1995 has an anterior process on the female genital shield but D. chilensis does not. Dinychus lepus Kontschán & Starý, 2014 from Madagascar has wide and large setae j1, and its female genital shield is short and linguliform, in contrast to the new species which has normal setae j1, and its genital shield is long and quadrangular.

Figures

FIGURES 10 – 12. Dinychus chilensis sp. nov. holotype, female. 10. Body in dorsal view. 11. Body in ventral view. 12. Peritreme.

FIGURES 13 – 21. Dinychus chilensis sp. nov. holotype, female. 13. Lateroventral view of gnathosoma and palp. 14. Chelicera. 15. Ventral view of leg I. 16. Ventral view of leg II. 17. Ventral view of leg III. 18. Ventral view of leg IV. 19. Intercoxal area of male paratype. 20. Ventral view of gnathosma of male paratype. 21. Lateral view of leg I of male paratype.

FIGURES 22 – 25. Dinychus chilensis sp. nov. paratype, deutonymph. 22. Body in dorsal view. 23. Anterior area of dorsal idiosoma. 24. Caudal area of dorsal idiosoma. 25. Body in ventral view.