Ramusella (Insculptoppia) arbaminchensis Ermilov, 2025, sp. nov.
Creators: name: Ermilov, Sergey G.
Publisher: name: Zenodo
Year: 2025
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Arachnida
Sarcoptiformes
Oppiidae
Ramusella
Ramusella arbaminchensis

description: Description of Ramusella (Insculptoppia) arbaminchensis sp. nov.
(Figures 3, 4)
Type material. Holotype (male) and six paratypes (two males and four females): southern Ethiopia, South Ethiopia Regional State, Gamo Zone, 6°01’36.7’’N, 37°35’42.7’’E, 1170 m a.s.l., 5 km East from the town Arba Minch, 1 km from the lake Abai, mineral soil (0–5 cm) in a mixed forest on the terrace (first layer of forest: Celtis sp., Ficus sycomorus, Schefflera sp., Acacia sp.; second layer of forest: Lemon sp., Coffee arabica) on the brown (black-brown) soil with light-medium loam soil texture, 7.XII.2018, dry season (L.B. Rybalov).
One paratype (one male): southern Ethiopia, South Ethiopia Regional State, Gamo Zone, 6°01’28.7’’N, 37°35’49.7’’E, 1179 m a.s.l., 5 km East from the town Arba Minch, 20–40 m from the lake Abai, mineral soil (0–5 cm) in a mixed deciduous forest on the alluvial organic soil, wet place, around water spots, 8.XII.2018, dry season (L.B. Rybalov).
The holotype is deposited in the collection of the Senckenberg Museum of Natural History, Görlitz, Germany; seven paratypes are deposited in the collection of the University of Tyumen, Museum Zoology, Tyumen, Russia. All specimens are preserved in 70% solution of ethanol with a drop of glycerol.
Diagnosis. Body length: 255–300. Costular line short, thin; transcostular line absent. Interbothridial region with three pairs of muscle sigillae. Rostral and interlamellar setae medium-sized, setiform, slightly barbed; lamellar and exobothridial setae short, setiform, roughened; bothridial seta long, with clavate head bearing four (sometimes three) long, setiform, barbed branches and three to five short ciliae. Notogastral seta c represented by alveolus; la, lm, lp, h 1 – h 3 long, p 1 – p 3 short, all setiform, sparsely barbed or nearly smooth. Surface of chelicera with ridges. Epimeral and anogenital setae setiform, nearly smooth or roughened. Ventrosejugal region with one pair of tubercles. Lateral longitudinal carina in podosomal region with tooth.
Description of adult. Measurements. Body length: 255 (holotype), 255–285 (male paratypes), 270–300 (female paratypes); notogastral width: 135 (holotype), 135–150 (male paratypes), 150–157 (female paratypes).
Integument (Fig. 3C). Body color light brown. Body nearly smooth; region between bothridium and acetabula I–III with typical dense tubercles (their diameter up to 2).
Prodorsum (Figs 3A, C). Rostrum rounded. Costular line short, thin; transcostular line absent. Interbothridial region with three pairs of muscle sigillae. Lateral ridge absent. Rostral (30–34) and interlamellar (30–37) setae setiform, slightly barbed; lamellar (15–19) and exobothridial (11) setae setiform, roughened; bothridial seta (49–52) with long, smooth stalk and shorter, clavate head bearing four (sometimes three) long, setiform, barbed branches and three to five short cilia. Postbothridial and sejugal tubercles not visible. Sejugal porose area (5–7) present, circular.
Notogaster (Figs 3A, C; 4A). Anterior margin of notogaster convex medially. Notogastral seta c represented by alveolus; other setae (la, lm, lp, h 1 – h 3: 34–45; p 1 – p 3: 17–22) setiform, sparsely barbed or nearly smooth. Opisthonotal gland opening and all lyrifissures well visible.
Gnathosoma (Figs 4B–D). Subcapitulum size: 60–64 × 45–49; subcapitular setae a (9–11) and h (13–15) setiform, roughened; m (13–15) setiform, barbed; all adoral setae (6) setiform, smooth. Palp length: 41–49; with typical setation: 0-2-1-3-9(+ω); postpalpal seta (4) spiniform, smooth. Chelicera length: 60–64; seta cha (17–19) setiform, dorsally ciliate; chb (11–13) setiform, barbed; surface of chelicera with four ridges (Fig. 4D).
Epimeral and lateral podosomal regions (Figs 3B, C). Epimeres with typical epimeral setal formula (3-1-3- 3); setae (1a, 2a, 3a: 7; 1c, 3b, 4a, 4b: 11) setiform, nearly smooth; others (1b, 4c: 17–19; 3c: 22–26) setiform, roughened. Ventrosejugal region with one pair of strong tubercles (each tubercle located posterior to insertion of 2a). Lateral longitudinal carina with tooth (well visible in ventral aspect; Fig. 3B). Discidium triangular, with pointed top.
Anogenital region (Figs 3B, C; 4A). With typical anogenital setal formula (5-1-2-3); genital (5) and anal (11–13) setae setiform, nearly smooth; aggenital and adanal setae (17–22) setiform, roughened. Adanal lyrifissure distinct, in typical position for genus (close and parallel to lateral side of anal plate).
Legs (Figs 4E–H). Claw of each leg smooth. Porose area on all leg segments not visible. Trochanter III with two or three posterior teeth. Formulas of leg setation and solenidia: I (1-5-2-4-20) [1-2-2], II (1-5-2-4-16) [1-1-2], III (2-3-1-3-15) [1-1-0], IV (1-2-2-3-12) [0-1-0]; homology of setae and solenidia indicated in Table 1; seta s on tarsus I eupathidial; setae a ′′and pv ′′on tarsus IV modified (brush-like); solenidia ω 1 on tarsi I, ω 1 and ω 2 on tarsus II and σ on genu III nearly bacilliform, φ 1 on tibia I and φ on tibia IV subflagellate; other solenidia setiform or rod-like.
Remarks. Ramusella (Insculptoppia) arbaminchensis sp. nov. is similar to R. (I.) rybalovi Ermilov, Shtanchaeva & Subias, 2022 from Ethiopia in the presence of the barbed branches on the bothridial seta as well as long dorsal notogastral setae and strong tubercles in ventrosejugal region. However, the new species differs from the latter by the morphology of the bothridial seta (with well developed head versus without head), the absence (versus presence) of the transcostula, postbothridial tubercle and prodorsal lateral ridge, and in the presence (versus absence) of the tooth on lateral carina in the podosomal region.
Etymology. The species name arbaminchensis refers to the town Arba Minch, five kilometers from which the new species was collected.
description: Published as part of Ermilov, Sergey G., 2025, Taxonomic contribution to knowledge of the oribatid mite genera Corynoppia, Ramusella and Wallworkella (Acari, Oribatida, Oppiidae), pp. 353-370 in Zootaxa 5621 (3) on pages 359-362, DOI: 10.11646/zootaxa.5621.3.4, http://zenodo.org/record/15262822