Plutomurus ruseki Barjadze, Kováč & Parimuchová, 2022

Barjadze, Shalva, Parimuchová, Andrea, Raschmanová, Natália, Maghradze, Eter & Kováč, Ľubomír, 2022, Two new species of Plutomurus Yosii (Collembola: Tomoceridae) from the Caucasus and central Europe, Zootaxa 5169 (3), pp. 252-266 : 259-264

Plutomurus ruseki Barjadze, Kováč & Parimuchová sp. nov.

Figs 16–28

Plutomurus sp. Barjadze et al. (2020b): 72

P. carpaticus Kováč & Krchová (2007) : 85

P. carpaticus Kováč et al. (1999) : 163 and 166 ( Tab. 2 )

P. carpaticus Kováč et al. (2002) : 163 (Tab. 3)

P. carpaticus Kováč et al. (2007) : 49 ( Tab. 1 )

P. carpaticus Kováč et al. (2016) : Appendix 1

P. carpaticus Lukáň et al. (2004) : 170

P. carpaticus Papáč et al. (2020) : 87 ( Tab. 1 )

P. carpaticus Raschmanová et al. (2008) : 463 and 469 (Tab. 3)

P. carpaticus Raschmanová et al. (2013) : 474 ( Tab. 2 )

P. carpaticus Raschmanová et al. (2015) : 806 ( Fig. 2 and Appendix)

P. carpaticus Raschmanová et al. (2018a) : 253 and Appendix

P. carpaticus Raschmanová et al. (2018b) : 393 ( Tab. 1 )

Type locality. SLOVAKIA, Muránska planina Plateau, Bobačka Cave, 680 m asl .

Type material. Holotype: Female on slide, transition zone (20 m from small entrance), hand collecting, rotten wood, 05.x.2000, leg. Ľ. Kováč, Nr. 173-00 ( UPJ).

Type material is ordered alphabetically after geomorphological regions:

Paratypes (n=42): Čierna hora Mts. , Veľká ružínska jaskyňa Cave, 614 m asl, ca. 90 m from cave entrance, deep zone, 2 ex. on slides, pitfall trap, 10.viii.-14.x.1996, leg. Ľ. Kováč, Nr. 1327-96 (1 ex. in UPJŠ and 1 ex. in IZISU) ; Liptovská kotlina Basin , Liskovská jaskyňa Cave, 500 m asl, Guánová sieň, deep zone, 2 ex. on slides, extracted from bait (wood shavings), 16.iv.-14.ix.2004, leg. Ľ. Kováč, Nr. 481-04 ( UPJŠ) ; ibidem: 50 m from cave entrance, transition zone, 1 ex. on slide, hand collecting from rotten wood, 14.ix.2004, leg. A. Mock, Nr. 491-04 ( UPJŠ) ; Low Tatras Mts. , Demänovská jaskyňa slobody Cave, 870 m asl, Sieň speleoterapie, transition zone (ca. 50 m from entrance), 1 ex. on slide, hand collecting on rotten wood, 27.ix.2000, P. Ľuptáčik, Nr. 127-00 ( UPJŠ) ; Suchá Cave , 903 m asl, Predsieň, transition zone, 1 ex. on slide, hand collecting, rotten wood, 12.v.2011, leg. Ľ. Kováč and P. Ľuptáčik, Nr. 275-11 ( UPJŠ) ; Slovak Karst , Jasovská Cave, 257 m asl, Komín, transition zone (50 m from show cave exit), 1 ex. on slide, hand collecting, dark cave sediment, 10.ix.1995, leg. Ľ. Kováč, Nr. 692-95 ( UPJŠ) ; Silická ľadnica Ice Cave , 466 m asl, microdepression on a moderate scree slope in front of cave entrance, dense herbal cover, ass. Cardamino-Chrysosplenietum alternifolii, Lunario-Aceretum, well-developed soil profile, 2 ex. on slides, extracted from soil samples, 18.v.2005, leg. Ľ. Kováč, Nr. 110-05, 113-05 ( UPJŠ) ; ibidem: 1 ex. on slide, extracted from soil samples, 11.v.2021, leg. N. Raschmanová, M. Marcin, ( UPJŠ) ; ibidem: pioneer soil and vegetation on rocky debris, ass. Cardamino-Chrysosplenietum with sparse mosses and liverworts and dense growth of Chrysosplenium alternifolium , 1 ex. on slide, extracted from soil samples, 18.v.2017, leg. N. Raschmanová, Nr. 73-17 ( UPJŠ) ; Stará brzotínska jaskyňa Cave, 258 m asl, entrance zone (~ 20 m from entrance), 2 ex. on slides, pitfall trap, 15.v.-08.vii.1998, leg. Ľ. Kováč, Nr. 296-98 (1 ex. in UPJŠ and 1 ex. in IZISU) ; ibidem: Veľká sieň, transition zone, 1 ex. on slide, pitfall trap, 12.iv.-06.ix.2010, leg. Ľ. Kováč, Nr. 426-10 ( IZISU) ; ibidem: entrance zone (~ 10 m from entrance), 2 ex. on slides, hand collecting, cave wall/sediment, 2.vii.2021, leg. N. Raschmanová, J. Hankoščák, A. Parimuchová ( UPJŠ) ; Zádiel Valley , 48°37.76’N, 20°49.81’E, 400 m asl, site on forested scree slope (E exposure, slope 35°) at the gorge bottom near the bank of Blatnica Creek (~10 meters), maple-lime wood (assoc. Aceri-Tilietum), mosses and sparse herbal cover, 1 ex. on slide, subterranean pitfall traps, depth of 65 cm, 19.x.2018 - 15.iv.2019, leg. N. Jureková, P. Ľuptáčik, A. Mock, Nr. 241-19 ( UPJŠ) ; Spišsko-gemerský kras Karst , Slovak Paradise , Psie diery Cave, 942 m asl, dark zone, 1 ex. on slide, pitfall trap, 06.ii.1997, leg. V. Košel, Nr. 6/97 ( UPJŠ) ; Vojenská jaskyňa Cave, 946 m asl, dark zone, 4 ex. on slides, pitfall trap, 28.i.-06.ii.1997, leg. V. Košel, Nr. 5/97 ( UPJŠ) ; Tatry Mts. , Belianske Tatry , Ľadová pivnica Cave, 1433 m asl, entrance zone, scree slope with coniferous forest soil and mosses, 2 ex. on slides, extracted from soil samples, 2.x.2018, leg. N. Raschmanová, Ľ. Kováč, M. Baňas, Nr. 305-18, 308-18 ( UPJŠ) ; Západné Tatry Mts. , Zadný úplaz Abyss, 1779 m asl, twilight zone, 3 ex. on slides, pitfall trap, 29.vi.-01.x.2010, leg. Ľ. Kováč, Nr. 715-10, 717-10 ( UPJŠ) ; ibidem: twilight zone, 2 ex. on slides, pitfall trap, 29.vi.-01.x.2010, leg. A. Mock, Nr. 709-10 ( UPJŠ) ; Nová Kresanica Abyss , twilight zone, small hall before Ženská priepasť, 1 ex. on slide, pitfall trap, 29.vi.-01.x.2010, leg. A. Mock, Nr. 721-10 ( UPJŠ) ; Veľká Fatra Mts. , Harmanecká Cave, 821 m asl, Izbica, entrance zone, 1 ex. on slide, pitfall trap, 07.v.-22.x.2002, leg. Ľ. Kováč, Nr. 187-02 ( UPJŠ) ; ibidem: 1 ex. on slide, hand collecting, rotten wood, leg. P. Ľuptáčik, Nr. 202-02 ( UPJŠ) ; Mažarná Cave , 830 m asl, entrance zone (15 m from entrance), 1 ex. on slide, hand collecting, surface of the sinter pool, 30.viii.1999, leg. Ľ. Kováč, Nr. 321-99 ( IZISU) ; Volovské vrchy Mts. , Jaskyňa nad kameňolomom Cave, 435 m asl, entrance zone, 2 ex. on slides, hand collecting, cave sediment and rotten wood, 21.vi.2021, leg. N. Raschmanová, Ľ. Kováč, M. Marcin, A. Parimuchová ( UPJŠ) ; Kolónia II Cave, 807 m asl, dark zone, 3 ex. on slides, hand collecting, 02.iii.2011, leg. A. Mock, M. Rendoš, Nr. 18-11 (2 ex. in UPJŠ and 1 ex. in IZISU) ; Šarkania diera Cave, 690 m asl, dark zone, 2 ex. on slides, hand collecting on rotten wood, 29.iv.2005, leg. Z. Višňovská, Nr. 175-06 ( UPJŠ) .

Additional material: Low Tatras Mts., pod Sinou, Acereto -Carpinetum, rendzina soil, 1 specimen on slide, 30.vi. 1960, leg. J. Rusek, Nr. 347 ( ISB)–originally designated as paratype of Plutomurus carpaticus by Rusek & Weiner 1978;Vihorlat Mts., Okna creek, Fagetum carpaticum typicum, under stones, 1 specimen on slide, 23.vi.1959, leg. J. Rusek, Nr. 208 ( ISB)—originally designated as paratype of P. carpaticus Rusek & Weiner 1978 .

Description. Body length 1.86–3.86 mm.

Colour. Body grey colored.

Scale distribution. Scales dorsally on Ant. I–II, head, Th. and Abd. segments, all leg segments, both sides of ventral tube and ventral side of furca.

Head. Ratio of antenna as 1.50–3.23. Ant. III–IV completely annulated. Eye patch with six well developed eyes ( Fig. 26 ). Head dorsally with one unpaired (A 0), and six paired Mc: two anterior (A 2, A 3), two interocular (S 2, S 4) and two postocular (Pa 3, Pa 5) distributed as in Fig. 26 . Posterior margin of head with a row of mesochaetae. Prelabral and labral chaetae smooth: prelabral chaetae four (2+2) ( Fig. 16 ); labrum with 554 papillate chaetae as typical for genus; distal margin of labrum with four elongate, thin–walled, flexible papillae. OML trifurcate, basal chaetae shorter than apical process; OML with four chaeta-like processes.

Body. Dorsal bothriotrichal formula as 2,1/0,0,1,2,0 ( Figs 27–28 ). Dorsal Mc formula: 5,2/3,3,4,3,2 or 3 ( Figs 27–28 ). Thorax macrochaetotaxy as in Fig. 27 . Th. II with three anterior (m 3, m 4, m 5) and two posterior (p 3, p 5) Mc; Th. III with two posterior (p 3, p 4) Mc. Abdominal macrochaetotaxy as in Fig. 28 : Abd. I–II each with three long posterior Mc (m 2, m 3, m 4),; Abd. III with four long Mc: two anterior (m2, m6) and two posterior (p1, p6) and one short Mc (p7) as typical for genus; Abd. IV with three posterior Mc: two short (C6, T7) Mc and one very long and thick (E3) Mc, rarely one mesochaeta on A6 position; Abd. V with 2–3 long posterior Mc (p2, p3 or p2, p3 p4) and one long lateral Mc ( Fig. 28 ).

Legs. Hind legs with well–developed trochanteral (6–25 chaetae) and femoral (11–26 chaetae) organs ( Fig. 17 ) with several elongated chaetae; tibiotarsal spine formula as 002, posterior side of tibiotarsus III with two outstanding inner Spine-like chaetae (arrows in Fig. 24 ). Tenent hair capitate ( Fig. 18A ). Ratio of claw III: Emp. III: tenent hair III as 1.21–2.23: 0.75–1.40: 1. Inner edge of claw on all legs with 2–4 teeth in total (b–c in Fig. 18A ): one characteristically minute proximal unpaired tooth (a in Fig. 18A ), one large unpaired tooth next to minute proximal unpaired tooth and 0–2 distal unpaired teeth, in total. Claw with long pseudonychia ( Fig. 18A ). Ratio of pseudonychium III: claw III inner edge as 0.32–0.54: 1. Unguiculus lanceolate, tapered, with 2 internal lamellae bearing 0–4 teeth ( Fig. 18A and B ).

Ventral tube. anterior basal, posterior basal and apicolateral sides with 10, about 11 and 12 smooth chaetae, respectively ( Fig. 22 ).

Tenaculum. Corpus with one or rarely two smooth chaetae; rami with 4 + 4 teeth ( Figs 19, 20 ).

Furca. Ratio manubrium: dens: mucro as 2.56–5.93: 5.26–8.48: 1. Outer margin of basal segment of dens with 2–3 apically acuminate macrochaetae ( Fig. 23d,e ; sockets with arrows in Fig. 25 ). Inner edge of dens with well differentiated spines ( Figs 23 a-c, 25); spines on basal segment forming 2–3 short and poorly organized rows with one or rarely two large spines apically; spines on distal segment forming a single row extending not more than half of distal segment’s length; basal edge of distal segment always with small spines intercalated between long spines, terminal one always largest long spine in row ( Figs 23 a-c, 25). Dental formula is variable as 3–11 I-II /1–6 I(II) 1–4 I 0–4 I 0–3 I 0–2 I (Arabic numbers represent small spines; Roman numerals in bold and Italics represent large spines, on basal/distal segments of dens). Mucro with two basal, 0 intermediate (rarely one) and two distal teeth (formula 202 or 212) ( Fig. 21 ).

Variability. All constant and variable characters are given in Tables 1–2 .

Discussion. The following 6 species of Plutomurus have been reported from Europe ( Barjadze et al. 2020b): P. baschkiricus ( Skorikow, 1900) , P. carpaticus Rusek & Weiner, 1978 , P. jeleznovodski Kniss & Thibaud, 1999 , P. kelasuricus Martynova, 1969 , P. sorosi Kniss & Thibaud, 1999 and P. unidentatus ( Börner, 1901) . The new species is similar to P. baschkiricus ( Skorikow, 1900) , P. carpaticus Rusek & Weiner, 1978 and P. unidentatus ( Börner, 1901) by the combination of the following characters: 1) number of prelabral chaetae (2+2); 2) shape of tenent hair (capitate); 3) formula of tibiotarsal spine-like chaetae (002) and 4) number of eyes (6) ( Jordana et al. 2012; Barjadze et al. 2020b).

The new species differs from P. baschkiricus by having well differentiated spines on dens, while P. baschkiricus has only narrow spines ( Skorikow, 1900; Martynova 1969).

The new species clearly differs from P. unidentatus by the number of Mc on the abdominal dorsum: 1) Abd. I with three Mc in the new species, while P. unidentatus has two on Abd. I and 2) Abd. IV with three Mc in the new species, while P. unidentatus has five on Abd. IV ( Barjadze et al. 2020b).

The new species is most similar to P. carpaticus , differing in the 1) number of postocular head Mc: two Mc in the new species, one in P. carpaticus and 2) number of Mc on Abd. II: three Mc in the new species, two in P. carpaticus ( Barjadze et al. 2020b) . Besides, based on mitochondrial COI gene, the pairwise genetic distance between P. carpaticus from Pieniny and P. ruseki sp. nov. is much greater than intraspecific distance in P. ruseki from two distant localities (Marcin et.al. unpublished data), thus confirming the new species status.

P. ruseki sp. nov. also differs from P. carpaticus in habitat preference and geographic distribution. The new species prefers entrance and twilight zone of the caves (troglophilic species), while P. carpaticus is a surface form, found only in forest soil and mosses ( Rusek & Weiner 1978 and our unpublished data), thus it may be considered as a trogloxene species. Moreover, P. carpaticus is geographically restricted to the surface habitats of Slovakian and Polish parts of the Pieniny Mountains, while the new species is known from subterranean habitats of several karst regions of Slovakia, and Western Carpathians. It is worth to mention that another possibly undescribed Plutomurus species was found on scree slope in the entrance zone of Silická ľadnica Ice Cave, which co-occurs with P. ruseki . It has head dorsum macrochaetotaxy as in P. ruseki and thoracic and abdominal dorsum macrochaetotaxy as in P. carpaticus . But further evaluation of this taxon will have to await the examination of individuals.

Etymology. The species is named in the honour of the late prof. Dr. Josef Rusek (Biology Centre, v.v.i., Institute of Soil Biology, České Budějovice, Czech Republic), an outstanding Collembola taxonomist and ecologist, and Ph.D. supervisor and a great colleague of the last author.

Ecology. It is a troglophilous species, considering the presence of pigmented body and 6+6 eyes. It lives mostly in entrance and twilight zone of caves, in several cases it was found to occupy even dark cave zone. It was also found to occupy forest soils and mosses.

Distribution. This species is distributed in different karst regions of the Western Carpathians, Slovakia, with exception of the Pieniny Mountains. A Plutomurus specimen with 3 Mc on the Abd. I and II sampled in Perlynna Cave (Eastern Carpathians, Ugolka Karst Massif) in Ukraine, probably belong to this species (Robert Vargovitsh, personal communication).

Figures

FIGURE 2. Entrance of Kozmani Cave. Photo: E. Maghradze (bar: 0.5 m).

FIGURES 16–25. Plutomurus ruseki sp. nov. 16, Prelabral chaetae (bar: 0.04 mm); 17, Trochanteral and femoral organs (bar: 0.06 mm); 18, Claw complex III (A) and Empodium III (B) of different legs (a, basal small tooth to internal lamellae; b, largest unpaired tooth and c additional unpaired tooth) (bar: 0.05 mm); 19, Tenaculum with 1 chaetae (bar: 0.06 mm); 20, Tenaculum with 2 chaetae (bar: 0.06 mm); 21, Mucro, chaetae and chaetal sockets omitted (bar: 0.02 mm); 22, Ventral tube (bar: 0.08 mm); 23, Macrochaetae and dental spines (a, small dental spine from the apical part of dens; b, big dental spine from the basal portion of the apical part of dens; c, terminal large spine on the apical part of dens; d, e, large lateral macrochaetae on the basal part of the dens) (bar: 0.03 mm); 24, Hind tibiotarsus, with spine-like chaetae (marked with arrows) (bar: 0.04 mm); 25, Dens with sockets of dental spines and lateral macrochaetae (arrows on them) (bar: 0.05 mm).

FIGURES 26–28. Dorsal chaetotaxy in Plutomurus ruseki sp. nov. 26, Head. A: Anterior macrochaetae, B: interocular Mc, C: postocular Mc; 27, Th. II–III; 28, Abd. I–V (big ovals and round circles near Ant. I represent eyes; large black circle—macro- chaeta; open circles—mesochaeta; squares with dots—bothriothricha; circles with a slash represent pseudopores).