Fimoscolex fridrichi Dudas, Brown & Bartz, sp. nov.

(Figure 15 and 16)

Holotype. COFM BRRS0503, adult, in annual crops under no-tillage, in 0–20 cm soil, by qualitative method, Panambi, Rio Grande do Sul, Brazil, -28.371324, -53.418971, 494 m asl, August 12, 2023, M.L.C. Bartz coll.

Paratype. COFM BRRS0452, one adult, annual crops under no-tillage system, in 0–20 cm soil, by TSBF method, Ajuricaba, Rio Grande do Sul, Brazil, -28.144014, -53.777835, 422 m asl, August 14, 2023, G.C. Francisco, M.L.C. Bartz, N. Durães, R. T. Dudas, R. Roani, T. Ferreira, W.C. Demetrio colls.

Other materials. COFM BRRS0448, two adults, native vegetation, in 0–20cm soil, by TSBF method, Ajuricaba, Rio Grande do Sul, Brazil, -28.167072, -53.814564, 419 m asl, August 14, 2023, G.C. Francisco, M.L.C. Bartz, N. Durães, R. T. Dudas, R. Roani, T. Ferreira, W.C. Demetrio colls. COFM BRRS0455, two adults, annual crops under no-tillage, in 0–20 cm soil, by TSBF method, Ajuricaba, Rio Grande do Sul, Brazil, -28.149816, - 53.774019, 385 m asl, August 14, 2023, G.C. Francisco, M.L.C. Bartz, N. Durães, R. T. Dudas, R. Roani, T. Ferreira, W.C. Demetrio colls. COFM BRRS0456, five adults, same information as holotype. COFM BRRS0460, two adults, same information as BRRS0455. COFM BRRS 0483, one adult, same information as holotype. COFM BRRS0495, one adult same information as holotype. COFM BRRS0517, one adult, annual crops under no-tillage system, in 0–20 cm soil, by TSBF method, Cruz Alta, Rio Grande do Sul, Brazil, -28.76386, -53.583866, 419 m asl, August 16 2023, G.C. Francisco, M.L.C. Bartz, N. Durães, R. T. Dudas, R. Roani, T. Ferreira, W.C. Demetrio colls. COFM BRRS0529, two adults, same information as holotype.

Etymology. The species was named in honor of farmer Marcos Fridrich, owner of the Faxinal Sul Farm, a reference in the management of the no-tillage system in his region.

External morphology. Holotype: body length 28 mm after ethanol fixation. Body mass: 0.05 g fresh weight (alcohol preserved). Number of segments: 104. Diameter: 1.8 mm in the pre clitellar region (segment X), 2.1 mm in the clitellum (segment XVI) and 1.5 mm in the post clitellar region (segment XXX). Paratype: length 48 mm after ethanol fixation. Body mass: 0.07 g, number of segments: 197. Diameter: 2.2 mm in segment X, 2.7 mm in the clitellum (segment XVI), and 1.9 mm in segment XXX. Body cylindrical, non-pigmented after fixation. Prostomium open epilobic. Setae closely paired, setae ab and cd barely visible from V onwards. Setal arrangement aa:ab:bc:cd: dd, 4.5:1.2:2.4:1:4.6 at segment XXX. Clitellum in XV–XXII saddle shaped. Genital marks or tubercula pubertatis absent. Female pore not seen. One male pore in XVI / XVII. Nephropores near B line.

Internal morphology. Septa thin and fragile in 7/8/9. Gizzard in VI, with average size (width x length) 0.8 mm x 0.6 mm. One pair of calciferous glands in XII of composite tubular internal shape. Intestine begins in XVI, with typhlosole commencing in the same segment. Five pairs of hearts, with last pair in XI. Paired testes sacs in XI under the beginning of the calciferous glands. Seminal vesicles from XII–CXXVII thickened ventrally with iridescent color. Ovaries in XIII. Spermathecae absent. Copulatory bulb is absent, although in the segment XVII there’s a lighter region that corresponds to the position of the external male pore.

Remarks. The position of the clitellum in Fimoscolex fridrichi sp. nov. is only similar to F. nivae Feijoo & Brown, 2018 —XIV–XXI–, although in F. nivae it is saddle shaped, while in F. fridrichi sp. nov. it is annular. The single male pore occurs in a swelling that occupies most of segment XVII, a distinctive characteristic. However, the most significant difference in F. fridrichi sp. nov. is the absence of the copulatory bulb, a feature encountered in all the specimens collected. While all other described Fimoscolex species possess a single chamber, F. fridrichi sp. nov. does not have any.