Pergalumna (Pergalumna) aquatica, Ermilov & Mary, 2025

Ermilov, Sergey G. & Mary, Nathalie J., 2025, Oribatid mites (Acari, Oribatida) of La Réunion Island, Zootaxa 5673 (1), pp. 119-131 : 125-127

Pergalumna (Pergalumna) aquatica sp. nov.

( Fig. 4 )

Type material. Holotype (male) and five paratypes (three males and two females): La Réunion, Ravine Sèche source Lesquelin amont, site RSS LAM/NA, forest stream, 770 m a.s.l., 21°13'10.5434" S, 55°21'46.1606" E, 08.ii.2019, collected by OCEA Consult'.

The holotype is deposited in the collection of the Senckenberg Museum of Natural History , Görlitz, Germany ; four paratypes are deposited in the collection of the University of Tyumen, Museum of Zoology, Tyumen, Russia ; one paratype is 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: 750–825. Body surface densely and slightly microgranulate. Rostrum rounded. Rostral, lamellar, and bothridial setae long, setiform, barbed; interlamellar seta vestigial. Dorsosejugal porose area present. Dorsosejugal suture complete, but poorly observed medially. Three pairs (A2 absent) of elongate oval porose areas with slightly diffuse edges; Aa located between la and lm, slightly closer to lm. Median pore absent. Opisthonotal gland opening lateral to A1; im anterolateral to A1; ip anteromedial to p 2; ih and ips close to each other, anterior to p 3. Subcapitular setae a and m longer than h, all similar in thickness. Genital plate with several strong, longitudinal striae (furrows). Epimeral setal formula: 1-0-2-3. All anogenital setae comparatively short, setiform, roughened or acicular. Circumpedal carina medium-sized. Postanal porose area elongate oval. Leg famulus inserted between seta ft’’ and solenidion ω 2; solenidion of tibia IV inserted in middle of dorsal side of segment.

Description of adult. Measurements. Body length: 810 (holotype), 750–825 (paratypes); notogaster width: 555 (holotype), 525–570 (paratypes). No difference between males and females in body size.

Integument. Body color brown. Body surface densely microgranulate (visible under high magnification, ×1000); genital plate with several strong, longitudinal striae (furrows); antiaxial side of leg femora I–IV and trochanters III, IV partially microtuberculate.

Prodorsum. Rostrum rounded. Lamellar and sublamellar lines long, thin, parallel, curving backwards at ventral end. Rostral and lamellar setae (71–75) setiform, barbed; insertion of le distanced from L; interlamellar seta vestigial; bothridial seta (105–109) setiform, roughened; exobothridial seta represented by alveolus. Dorsosejugal porose area elongate oval (37–52 × 9–11), located posterolateral to in. Dorsophragma medium-sized, elongated.

Notogaster. Dorsosejugal suture complete, but slightly developed medially. All notogastral setae represented by setal alveoli. Three pairs (A2 absent) of elongated porose areas with slightly diffuse edges: Aa (77–94 × 34–37) and A1 (65–75 × 34–37 elongate oval; Aa distanced from pteromorphal hinge, located between la and lm, slightly closer to lm; A3 (41–52 × 26–37) oval. Median pore absent in both genders. Opisthonotal gland opening and all lyrifissures distinct: gla lateral to A1; im anterolateral to A1; ip anteromedial to p 2; ih and ips close to each other, posterolateral to gla and anterior to p 3.

Gnathosoma . Generally similar to G. (G.) reunionensis sp. nov. Size of subcapitulum: 184–187 × 161–164; subcapitular (a, m: 34–37; h: 22) and adoral (15) setae setiform, roughened; a, m, h similar in thickness. Length of palp: 131–134; setation: 0-2-1-3-9(+ω); postpalpal seta (7) spiniform, smooth. Length of chelicera: 217–221; setae (cha: 82; chb: 45–49) setiform, barbed.

Epimeral and lateral podosomal regions. Epimeral setal formula: 1-0-2-3; 4a and 4b (both: 4–7) acicular; other setae (3c, 4c: 34–37; 1b, 3b: 22–26) setiform, roughened. Circumpedal carina directed to insertion of 3b, but not reaching it.

Anogenital region. Anogenital setal formula: 6-1-2-3; genital (g 1, g 2: 22–26; g 3: 15–15; g 4: 11–15; g 5, g 6: 4–7), aggenital (4–7), anal (19–26), and adanal setae (ad 1: 22–26; ad 2: 19–26; ad 3: 15–26) setiform, roughened or acicular; anterior edge of genital plate with two setae; aggenital seta located between genital and anal plates, closer to former; ad 1 and ad 2 posterior, ad 3 lateral to anal plate and iad; distance ad 1 – ad 2 smaller than ad 2 – ad 3. Adanal lyrifissure located close and parallel to posterior half of anal plate. Postanal porose area elongate oval (75–86 × 15–22).

Legs. Generally similar to G. (G.) reunionensis sp. nov., but famulus inserted between seta ft’’ and solenidion ω 2, and solenidion of tibia IV inserted in middle of dorsal side of segment.

Remarks. Pergalumna (Pergalumna) aquatica sp. nov. is similar to P. (P.) silvatica Hammer, 1961 (see also Ermilov et al. 2014) from the Neotropical region in its main morphological traits: body size large; rostral and lamellar setae long; interlamellar seta comparatively short; bothridial seta setiform; three pairs of elongated notogastral porose areas (Aa, A1, A3), with Aa located between la and lm; median pore absent; all anogenital setae comparatively short. The new species differs from P. (P.) silvatica by the body size (length: 750–825 versus 863– 1000), the shape of the rostrum (rounded versus with trapezoid ledge), the surface of the genital plate (with strong, longitudinal striae versus without striae), and the presence (versus absence) of the postanal porose area.

Etymology. The species name aquatica refers to the place of origin of the new species, water environment.

Figures

FIGURE 4. Pergalumna (Pergalumna) aquatica sp. nov., adult (sculpturing shown partially):A—dorsal view; B—ventral view (legs and right pteromorph omitted); C—anterior part of prodorsum, anterior view; D—right lateral view (legs and pteromorph omitted); E—posterior view. Scale bars 200 μm.