Trhypochthoniellus grandensis, Ermilov & Mary, 2025

Ermilov, Sergey G. & Mary, Nathalie J., 2025, Oribatid mites (Acari, Oribatida) from riverine environments in New Caledonia, Persian Journal of Acarology 14, pp. 455-464 : 458-462

Trhypochthoniellus grandensis sp. nov. ( Figs. 9 –21)

http://zoobank.org/ urn:lsid:zoobank.org:act:906C1FC0-6E21-4615-A111-BF853555F28A

Type material

Holotype (female) and nine paratypes (nine females): New Caledonia, Grande Terre Island , Kwé Ouest River, 22° 17' 45.8912" S, 166° 55' 37.5985" E, 177 m a.s.l., location 1 (KO4-20-I), benthic sample (N.J. Mary).

Type deposition

The holotype is deposited in the collection of the Senckenberg Museum of Natural History , Görlitz, Germany ; three paratypes are deposited in the collection of the University of Tyumen, Museum of Zoology, Tyumen, Russia ; six paratypes are in the personal collection of the first author. All specimens are preserved in 70% solution of ethanol with a drop of glycerol .

Diagnosis

Body length: 510–555. Rostrum nasiform, with short, longitudinal ridges. Notogaster and anogenital region with slight polygonate ornamentation. Bothridial seta and bothridium absent. Relative length of prodorsal setae: in ˃ le ˃ ro. Fourteen pairs of notogastral setae (p 3 absent; f 1 as alveolus) setiform, nearly smooth; relative length of notogastral setae: c 3, e 2, h 1, h 2, p 2 ˃ cp, e 1, h 3, p 1 ˃ d 2 ˃ c 1, c 2, d 1, f 2). Six pairs of genital setae. All leg tarsi with three claws.

Description

Measurements – Body length: 540 (holotype), 510–555 (paratypes); body width: 300 (holotype), 277–300 (paratypes).

Integument – Body color light brownish to light yellowish. Body surface densely porose (clearly visible under high magnification, ×1000). Notogaster and anogenital region with poorly observed polygonate ornamentation. Rostral region with several short, longitudinal ridges.

Dorsal view; 10. Rostrum, dorsal view; 11. Ventral view.

Prodorsum ( Figs. 9, 10 , 12 ) – Rostrum distinctly protruding, nasiform, narrowly rounded, curved ventrad. Rostral (45–49), lamellar (79–82), interlamellar (150–157), and first exobothridial (19–26) setae setiform, nearly smooth. Distance between insertions of setae le–le shorter than ro–ro. Bothridial seta and bothridium absent. Second exobothridial seta represented by alveolus.

Notogaster ( Figs. 9 , 12 ) – With parallel lateral sides or slightly dilated medioposteriorly; anterior margin nearly straight; posterior margin rounded. Fourteen pairs of setae, including alveolus of f 1 (seta p 3 completely absent); c 1, c 2, d 1, f 2: (19–22), d 2 (30–37), cp, e 1, h 3, p 1 (52–64), and c 3, e 2, h 1, h 2, p 2 (75–82) setiform, nearly smooth; f 1 slightly distanced from h 1. Distance between insertions of setae c 1 – c 1 subequal to d 1 – d 1 or slightly longer. Opisthonotal gland opening and all lyrifissures distinct.

Gnathosoma ( Figs. 13–15 ) – Subcapitulum size: 101–105 × 109–112; subcapitular setae (a: 22; m, h: 11–13) setiform, roughened; a thicker than m and h; adoral seta or 1 (9–11) leaf-shaped, smooth versus or 2 (11–13) and or 3 (11–13) setiform, roughened. Palp length: 67–71; setation: 0–1–1–1– 9(+ω). Chelicera length: 109–112; seta cha (13) setiform, barbed; chb (19) setiform, roughened.

Epimeral and lateral podosomal regions ( Figs. 11 , 12 ) – Epimeral setal formula: 3–1–3–2; setae 1a, 1c, 2a, 3a, 4a (5) spiniform; 1b, 3b, 3c, 4c (19–22) setiform, roughened.

Anogenital region ( Figs. 11 , 12 ) – Anogenital formula: 6–0–1–2; genital (26–30), anal (19–22), and adanal (26–30) setae setiform, roughened. Anal lyrifissure not visible; adanal lyrifissure distinct.

Legs (Figs. 16–21) – Tridactylous; claws similar in thickness, slightly barbed on dorsal side. Formulas of leg setation and solenidia: I (1–6–3–4–14) [1–1–3], II (1–5–3–3–12) [1–1–2], III (2–2– 2–2–10) [1–1–0], IV (1–2–2–2–11) [0–1–0]; homology of setae and solenidia indicated in Table 1.

Figures 16–21. Trhypochthoniellus grandensis sp. nov. (adult) – 16. Leg I (trochanter omitted), left paraxial view; 17. Tarsus, tibia, genu, and anterior part of femur of leg I (solenidia and many dorsal setae except their insertions omitted), left, ventral view; 18. Leg II (trochanter omitted), left paraxial view; 19. Tarsus, tibia, and anterior part of genu of leg II (solenidia and many dorsal setae except their insertions omitted), left, ventral view; 20. Leg III, left, antiaxial view; 21. Leg IV, left, antiaxial view.

Comparison

Trhypochthoniellus grandensis sp. nov. is similar to T. malaconothroiformis Ermilov, Hugo-Coetzee & Theron, 2017 from South Africa, having a medium number of genital setae (less than eight pairs), the presence of notogastral setae that vary greatly in length, and in the absence of the bothridial seta, bothridium, and prodorsal polygonate ornamentation. The new species differs from the latter in having six (versus seven) pairs of genital setae; the morphology of the rostrum (nasiform, with several longitudinal ridges versus not nasiform, with median, longitudinal furrow); the relative lengths of the notogastral setae (c 3, e 2, h 1, h 2, p 2 ˃ cp, e 1, h 3, p 1 ˃ d 2 ˃ c 1, c 2, d 1, f 2 versus p 2 ˃ c 3, cp, e 2, f 2, h 1, h 2, h 3, p 1 ˃ c 2, d 2, e 1 ˃ c 1, d 1); the presence (versus absence) of slight polygonate ornamentation on the notogaster and in the anogenital region; and the number of setae on some leg segments (it'' of tarsus I present versus absent; l' of trochanter III present versus absent).

Etymology The species name grandensis refers to the island of origin, Grande Terre.

Figures

Figures 9–11. Trhypochthoniellus grandensis sp. nov. (adult; gnathosoma and legs except trochanters omitted) – 9.

Figures 12–15. Trhypochthoniellus grandensis sp. nov. (adult) – 12. Right lateral view (gnathosoma and legs except trochanters III, IV omitted); 13. Subcapitulum (dissected), ventral view; 14. Palp (dissected), right, antiaxial view; 15. Chelicera (dissected), right, antiaxial view.