Redescription of Pronematus ubiquitus (McGregor, 1932) (Acari, Iolinidae), description of two new species and redescription of two additional species with a review of and key to all Pronematus species Author UeckermannK, Edward A. Unit for Environmental Sciences and Management, Potchefstroom Campus, North West University, Author De VisK, Raf M. J. Research Station for Vegetable Production (PSKW), 2860 Sint-Katelijne-Waver, Belgium. Author ReybroeckK, Eva Research Station for Vegetable Production (PSKW), 2860 Sint-Katelijne-Waver, Belgium. Author K, Lore Vervaet Laboratory of Agrozoology, Department of Plants and Crops, Faculty of Bioscience Engineering, Ghent Author Lommel, Wendy Van Research Centre Hoogstraten, Voort 71,2328 Meerle, Belgium. Author DewitteK, Justine Vegetable Research Centre, Karreweg 6, 9770 Kruisem, Belgium. Author Foqué, Dieter Flanders Research Institute for Agriculture, Fisheries and Food - ILVO, Burg. Van Gansbergelaan 92, Author GautamK, Sandipa University of California. Lindcove Research and Extension Center. 22963 Carson Avenue, Exeter, CA Author K, Yuling Ouyang University of California. Lindcove Research and Extension Center. 22963 Carson Avenue, Exeter, CA Author VangansbekeK, Dominiek Biobest Group N. V., Ilse Velden 18, 2260 Westerlo, Belgium. Author ClercqK, Patrick De Laboratory of Agrozoology, Department of Plants and Crops, Faculty of Bioscience Engineering, Ghent Author K, Thomas Van Leeuwen Laboratory of Agrozoology, Department of Plants and Crops, Faculty of Bioscience Engineering, Ghent text Acarologia 2024 2024-02-29 64 1 277 311 http://dx.doi.org/10.24349/tyki-9xlp journal article 10.24349/tyki-9xlp 2107-7207 10787663 Pronematus species review and key for the confirmed species Kaźmierski (1989) listed tree confirmed species. André (2021) actualized the list on the wikispecies website and counted 11 species (accessed on 08/2023). Revising the descriptions, we consider the following: Figure 15 Dorsal setae of Pronematus spp. Bothridial seta bo : a – P. ubiquitus , b – P. brasiliensis n. sp. . Seta ro : c – P. ubiquitus , d – P. brasiliensis n. sp. . Seta f1 : e – P. ubiquitus , f – P. brasiliensis n. sp. , g – P. debilis (bar = 20 μm, after Tseng (1985)) , h – P. perpusillus 17 μm (after Tseng (1985)) . A dorsal seta: i – P. oryzae – (after Menon et al. (2007)) . • Tseng (1985) described P. debilis and P. perpusillus including the leg chaetotaxy. The species description states “The debilis differs from all known Pronematus by having 3 pairs (sic) of setae on femur II”. We suppose that Tseng (1985) based the identification on the genus description of Baker (1965) which states 2 setae on femur II. Actually, the genus description has 3 setae on femur II ( André 1980 ). Tseng states “3 ag setae located anterior to the genital aperture”. The genus description of Baker (1965) mentions “4 ag setae anterior to and laterad from the genitalia”. We assume that the lateral ag4 is therefore present but not mentioned. Most dorsal setal lengths are given. When compared to P. ubiquitus , the distinguishing character of P. debilis are the lanceolate, strongly tapering dorsal setae, the deviating lengths of setae la 26, c1 18, c2 26, d1 18 & f2 45 and ( pζ ) 26 subequal and subequal with length of tarsus. The second Tseng (1985) species is P. perpusillus . When compared to P. ubiquitus , the distinguishing characters of this species are the lanceolate, strongly tapering setae; the short dorsal setae; and the deviating lengths of setae la 14, c1 13, c2 13, d1 14, f1 17 & f2 .25. This species resembles P. brasiliensis n. sp. as setal lengths fall within the range of those of P. brasiliensis , but the dorsal setae are conspicuously lanceolate. When comparing with P. ubiquitus and P. brasiliensis n. sp. , the dorsal setae of these species are also somehow lanceolate ( Figure 15 ). We conclude that redescription of both species is needed to confirm the difference in setal forms and the presence of ag4 . • Menon et al. (2007) described P. oryzae . Their description is more detailed, the mean and standard deviation of the dorsal setae are shown (not the range, we calculated the 99% confidence interval, see Table 5 ), and although leg chaetotaxy is not described, trochanter I appears without a seta on their drawing of leg I. We therefore believe that this species is indeed a Pronematus . When compared to P. ubiquitus , the distinguishing characters of this species are the short dorsal setae, ro , la , c1 , c2 , d1 , e1 , f1 & f2 . The following species cannot be assured as belonging to Pronematus with certainty. We therefore add these five species to the list of species inquirendae . Redescriptions are needed: • Ryke and Meyer (1960) described P. sensillaris in a minimalistic way having ωI 22, bo 22, prodorsal setae 15-19 and dorsal setae 12-20, tarsus I 23, tibia I 19 and ft″ζ 23. This long ωI and short ft″ζ are characteristics of male Pronematus . Study of the holotype is necessary to confirm that it is indeed a female. We could not locate the types of this species. • Pronematus sextoni ( Baker 1968 ) . Kaźmierski (1998) retained it on the list of Pronematus spp. Some authors have mentioned the presence in Türkiye ( Soysal and Akyazi 2018 ; Çobanoglu and Kaźmierski 1999 ), India and Africa according to Gupta and collaborators in Soysal and Akyazi (2018) , Iran ( Darbemamieh et al. 2021 ). Nevertheless, no redescriptions were made, and the description lacks any detail including leg setation as to assure it is a Pronematus . Many other species of Baker (1968) are now transferred to other genera and in our opinion redescription is needed to maintain it in the genus Pronematus . • Gupta and Paul (1985) described P. indiana and P. bengalensis . The authors did not determine the leg chaetotaxy, but on the drawings of tarsus II of both species 3 dorsal setae appear which means that there would be 7 setae on tarsus II (4 distal setae unclear). Additionally, the terminal eupathidia on tarsus I of both species are very long, the prorals shorter, subequal. Finally, the habitat is birds’ nests, while all other Pronematus spp. live on plants. This characteristic is found in e.g., Pseudopronematulus , which live on fungi or in litter. Therefore, we doubt that these two species belong to the genus Pronematus . • Gupta and Paul (1992) described P. saularis . The authors did not determine the leg chaetotaxy, but on the drawing of leg I, a seta appears on trochanter I, so this species cannot be a Pronematus . Additionally, we studied the holotype of P. tenuisetosus , one of the species inquirendae , and concluded that it is a Pseudopronematulus . This species will be treated in another publication. We retain 8 confirmed Pronematus species : P. debilis , P. karrooi , P. oryzae , P. perpusillus , P. rykei , P. juglandi , P. brasiliensis n. sp. and P. ubiquitus . However, 4 species ( P. debilis , P. karrooi , P. perpusillus and P. rykei ) need full redescription including the range of the intraspecific variation. Possibly, only the combination of morphometric, genetic studies and crossbreeding experiments can define differences between species with certainty ( Table 5 ). Nevertheless, based on the available information, we developed the following key for separating the confirmed species. Some character measurements are close to each other, in case of doubt we refer to table 5 for all (known) measurements. 1 Dorsal setae lanceolate, acutely tapering from the widened proximal portion..............2 — Dorsal setae not lanceolate, not acutely tapering from the widened proximal portion...... 3 2 (1) Dorsal setae longer, lengths of setae la 26, c1 18, c2 26, d1 18, f1 29 & f2 45; ( pζ ) subequal 26.................................................................. P. debilis — Dorsal setae shorter, lengths of setae la 14, c1 13, c2 13, d1 14, f1 17 & f2 25............. .......................................................................... P. perpusillus 3 (1) Dorsal setae very short to short: ro <20, c1 <17, d1 <19, e1 ≤ 21................... 4 — Dorsal setae longer: ro > 20, c1 > 20, d1 > 20, e1 ≥ 22................................ 5 4 (3) Dorsal setae very short: la 10.3 ± 2.39 (9.3 - 11.2), c1 11.3 ± 2.26 (10.4-12.3), c2 12.3 ± 2.7 (11.2-13.4), d1 11.6 ± 1.84 (10.9-12.3), e1 13.2 ± 2.65 (12.1-14.3) & f1 16.8 ± 3.72 (15.3-18.3) (mean ± st. dev (confidence interval 99%))........................... P. oryzae — Dorsal setae short: la 15-23, c1 14-16, c2 15-18, d1 15-18, e1 15-21 and f1 15-24. Palptarsal dorsal seta d forked (not always visible)............................... P. brasiliensis n. sp. 5 (3) Prodorsal seta la 25.4, dorsal setae c1 27.1, Palptarsal dorsal seta d forked...... P. rykei — Prodorsal seta la 22 or less, dorsal setae c1 25 or less, Palptarsal dorsal seta not forked or not known to be forked...................................................................6 6 (5) Dorsal setae h1 17, f2 25.3, bothridial seta ( bo) 28.4........................ P. karrooi — Dorsal seta h1 21 or longer, f2 30 or longer, bothridial seta ( bo) 30 or longer.............7 7 (6) Dorsal seta h1 25-27, ventral setae 1b 20-22, 1c 19-20, 4b 13-18 and ag4 8-11.......... ............................................................................ P. juglandi — Dorsal seta h1 21-24, ventral setae 1b 14-18, 1c 13-18, 4b 19-20 and ag4 13-14........... ........................................................................... P. ubiquitus