Troglocheles christiani Zacharda, 2011

Zacharda, Miloslav, Isaia, Marco & Piva, Erminio, 2011, New troglobitic species of the genus Troglocheles (Acari: Prostigmata: Rhagidiidae) from caves in northern Italy and Austria, with a key to adult species of the genus, Journal of Natural History 45 (11 - 12), pp. 641-666 : 656-663

Troglocheles christiani Zacharda , sp. nov.

( Figures 10–12 )

Material examined

Holotype. Adult female, Lower Austria, district of Lilienfeld, the Lower Austrian Calcareous Alps , the Gutenstein Alps in the region Reisalpe-Hergerberg , Türkenloch Cave near Kleinzell , 721 m a.s.l., 47 ◦ 55 ′ 48.5 ′′ N, 15 ◦ 56 ′ 37.8 ′′ E, the Austrian cave cadastre 1866 / 17, length: 219 m, depth: 23 m, dolomite of the Upper Triassic , E. Christian leg. in an unbaited pitfall trap, exposed 23 February to 5 October 1992 in the “Grosser Dom” cave section; deposited in the Museum of Biological Diversity , Ohio State University, Type No. OSAL007443 .

A, B

Paratypes. Deposited with the holotype; one adult male; one adult female, same data as holotype, OSAL007441 ; OSAL007442 , respectively .

Diagnosis

Rhagidial organ I comprises eight rhagidial solenidia lying obliquely in separate depressions; rhagidial organ II with five to six rhagidial solenidia lying in separate oblique depressions, small vestigial spiniform famulus (ε) inserted laterad of the first proximal rhagidial solenidion antiaxially. Spiniform solenidia on tibiae and genua long, well-developed. Ratio of tarsus I length to dorsoventral width 8.00–9.33, ratio of palpal tarsus length to dorsoventral width 3.84–4.60. Bothridial setae sc 1 not overlapping disjugal suture.

B,C,D,G

Description – adult female (two examined)

Length of idiosoma 928–1280 µm. Ratio of leg I length to idiosomal length 1.95–2.62.

Gnathosoma . Subcapitulum slender, trapezoidal ( Figure 11E ), ratio of length to breadth 1.45–1.50; distal hypostomal lips with spiniform internal and slightly serrate external malar processes; adoral setae nude and overlapping apex of subcapitulum; proximal subcapitular setae pointed, pubescent, external pair slightly longer than internal pair. Dorsal surface of chelicera with saddle-shaped depression slightly distal to level of bases of digits ( Figure 11A ); cheliceral digits strikingly long, slender; fixed digit terminates in two large cusps, smooth along masticatory surface and with small lateral fissure at level of bases of digits; movable digit smooth along masticatory surface and sparsely wrinkled at base (see in lateral aspect). Chelicera with two setae inserted distad of articulation of movable digit, the distance between insertions of the cheliceral setae on the fixed digit almost the same as length of proximal cheliceral seta; tip of distal seta slightly overlaps apex of fixed digit. Length of chelicera 412–455 µm, dorsoventral width 132–142 µm, length of movable digit 180–208 µm, length of proximal and distal cheliceral setae 33–43 and 89–99 µm, respectively, distance between their insertions 36 µm. Ratios: cheliceral length to dorsoventral width 3.12–3.20; length of movable digit to length of chelicera 0.45; length of movable digit to dorsoventral width of chelicera 1.37–1.46. Palpal tarsus shorter than femorogenu ( Figure 11F ), ratio of length to width of tarsus 3.84–4.61. Length of palpal trochanter, femorogenu, tibia and tarsus 56–66, 231, 82–105 and 165–198 µm, respectively. Number of setae and solenidia (in brackets) on palpal trochanter, femorogenu, tibia and tarsus 0-2-3-10(1), respectively; tarsal solenidion spiniform, long, erect.

Prodorsum. Naso well-developed ( Figure 10A ), with pair of internal vertical setae v 1. Bothridial setae sc 1 filiform, finely pubescent, not overlapping disjugal suture. Length of setae: v 1 92–96, v 2 69–76, sc 1 152–155, sc 2 165–188 µm.

Opisthosomal dorsum and anal region. Cupules ia positioned proximad of insertions of setae c 2, im laterad and slightly distad of insertions of e 1, ip laterad and slightly distad of insertions of f 1, ih positioned laterodistad of insertions of adanal setae ad 1 ( Figure 10A ). Length of setae: c 1 82–99, c 2 191–214, d 1 82–89, e 1 82–89, f 1 125–132, f 2 76–82, h 1 182, h 2 92–96, ps 1 155–162, ps 2 99, ps 3 76–86, ad 1 68–70 µm.

Podosoma. Coxae I, II, III, IV with 3-1-5-3 finely pubescent setae, respectively ( Figure 10B ).

Genital region. Genital valves each with five finely pubescent genital setae (g) of similar length, about 33–43 µm, arranged evenly along medial edge of valve. Five pairs of pointed aggenital setae (ag) of similar length, about 66–92 µm. Length of genital valves 138–158 µm.

Legs. Leg I 2432 –2496 µm long, about 1.95–2.62 as long as idiosoma. Empodia of all legs setulose, longer than claws, no ventrobasal clawlets on claws ( Figure 11G ). Trochanters I strikingly elongated ( Figure 10B ). Number of setae and solenidia [solenidia and famulus (ε) bracketed], respectively, on legs I-II-III-IV ( Figure 12 ): trochanters 1-1-2-2; basifemora + telofemora 5+4-5+5-4+4-3+4; genua 16(1)-8(1)- 9(1)-8; tibiae 12(2)-6(2)-8(2)-7(1); tarsi 17(8+ ε)-16(5 or 6+ ε)-15-14. Spiniform solenidia on leg segments long. Genua I and II each with one erect spiniform distoventral solenidion (σ); genu III with one spiniform dorsolateral, mediodistal solenidion. Tibia I with one erect spiniform dorsodistal solenidion (Φ), and one dorsodistal rhagidial solenidion ( Figure 12F ); tibia II with one spiniform erect dorsodistal solenidion, and one lanceolate dorsodistal solenidion slightly protruding from deep pit with broadly open surface pore ( Figure 12G ); tibia III with two adjacent erect spiniform dorsomedial to mediodistal solenidia; tibia IV with one erect spiniform dorsal, medioproximal solenidion. Tarsus I slender, its tip slightly tapers in lateral view, ratio length to width 8.0–9.33, with eight rhagidial solenidia (ω) lying obliquely in separate depressions dorsodistally, stellate famulus (ε) inserted between the first and second proximal rhagidial solenidion antiaxially ( Figure 11B ); tarsus II with five to six rhagidial solenidia lying in separate oblique depressions, and small vestigial spiniform famulus (ε) inserted laterad of the first proximal rhagidial solenidion antiaxially ( Figures 11C,D ).

Adult male (one examined), smaller than female, length of body 992 µm, clubshaped sperm sac showing through the opisthosomal tegument, otherwise as in female.

Affinities

Troglocheles christiani sp. nov. is very similar to T. vornatscheri from which it can be distinguished by the following principal characteristics. (1) Rhagidial organ II comprises five to six rhagidial solenidia and the very small, vestigial spiniform famulus (ε) is inserted laterad of the first proximal rhagidial solenidion; in T. vornatscheri rhagidial organ II comprises four to five rhagidial solenidia and the spiniform famulus (ε) is clearly discernible. (2) Tibia II with one long dorsodistal spiniform solenidion; in T. vornatscheri the spiniform solenidion on tibia II is laterodorsal, proximal.

Etymology

The epithet christiani honours Professor Erhard Christian, the Austrian soil zoologist and speleobiologist, The University of Natural Resources and Applied Life Sciences, Vienna, who provided the material for this species. Feminine gender.

Remark

Troglocheles christiani sp. nov., in having a high number of solenidia in rhagidial organ I and the relatively elongated appendages, is evidently morphologically adapted to life in the subterranean habitat. It can be considered a troglobiont.

The Austrian speleobiologist Josef Vornatscher started speleobiological investigations in the Türkenloch cave in 1933. Willmann (1938), who determined the rhagidiid mites collected in this cave, used the name Rhagidia strasseri (Prof. Christian, pers. comm.).

Key to adults of the genus Troglocheles

1. Coxae I-II-III-IV with 3-1-4-3 ciliated setae, respectively. Insertions of cheliceral setae on fixed digit strikingly far apart so that tip of proximal seta does not reach insertion of distal seta ( gineti species group).................... 2 Coxae I-II-III-IV with 3-1-5-3 ciliated setae, respectively. Distance between insertions of cheliceral setae almost the same as length of proximal cheliceral seta.................................................................... 3

2. Chelicerae elongated, cheliceral fixed digit slender, rhagidial organs I and II comprise 12 and seven rhagidial solenidia, respectively. Troglobiotic, France........................................... T. gineti (Cooreman, 1959)

Chelicerae with short, robust digits; fixed digit of chelicera flattened laterally; rhagidial organ I and II each comprising four rhagidial solenidia. In subterranean voids of the talus slope in subnival zone, Oetztal Alps...................................................... T. aggerata Zacharda, 2000

3. Spiniform solenidion on tibia I positioned dorsomedially or medioproximally ( strasseri species group)...................................... 4

Spiniform solenidion on tibia I positioned dorsodistally ( vornatscheri species group)..................................................................8

4. Rhagidial organs I and II each comprising four rhagidial solenidia........ 5

Rhagidial organs I, and usually also II, each comprising more than four rhagidial solenidia...................................................... 6

5. Prodorsal filiform bothridial setae sc 1 overlap disjugal suture and reach almost to insertions of successive opisthosomal setae c 1. Spiniform solenidia on leg segments short, tiny; spiniform solenidion on tibia IV absent. Epigean and hypolithic, Oetztal Alps................. T. archetypica Zacharda, 2000

Prodorsal filiform bothridial setae sc 1 do not reach to insertions of opisthosomal setae c 1. Spiniform solenidia on tibiae I, II, III, IV strikingly long; spiniform solenidion on tibia IV present. Troglobiotic, French Pyrenees............................................... T. vandeli Zacharda, 1987

6. Rhagidial organs I and II comprise five and four rhagidial solenidia. Troglobiotic, northern Italy................... T. quinquesolenidiata sp. nov.

More than five rhagidial solenidia in rhagidial organ I.................... 7

7. Rhagidial organs I and II comprise six rhagidial solenidia each. Troglobiotic , Styria, Austria.......................... T. strasseri s. str. (Willmann, 1932)

Rhagidial organ I comprises seven to 11 rhagidial solenidia; rhagidial organ II comprises five to seven rhagidial solenidia. Troglobiotic in Austria and Germany...................................... T. spp. ( strasseri sensu lato)

8. Rhagidial organ I and II comprise eight and four to six rhagidial solenidia, respectively; rhagidial solenidia on tarsus III absent.......................9

Rhagidial organ I comprises 12 to 14 rhagidial solenidia (examine both tarsi I); rhagidial organ II comprises four (exceptionally three and five) rhagidial solenidia. Tarsus III with two adjacent dorsodistal rhagidial solenidia lying in separate depressions axially (rhagidial organ III). Troglobiotic, Piedmont, northwestern Italy........................................ T. lanai sp. nov.

9. Rhagidial organs I and II comprise eight and four rhagidial solenidia, respectively. Spiniform famulus (ε) in rhagidial organ II well discernible, positioned laterad of proximal rhagidial solenidion antiaxially. Troglobiotic, Austria......................................... T. vornatscheri (Willmann, 1953)

Rhagidial organs I and II comprise eight and five to six rhagidial solenidia, respectively. Spiniform famulus (ε) in rhagidial organ II tiny, almost indiscernible, positioned laterad of proximal rhagidial solenidion antiaxially. Troglobiotic, Austria.................................. T. christiani sp. nov.

Figures

Figure 10. Troglocheles christiani sp. nov., adult female; (A) dorsum; (B) venter (for setal notation see Description).

Figure 11. Troglocheles christiani sp. nov., adult female; (A) chelicera, lateral aspect; (B) rhagidial organ I, dorsal aspect; (C,D) rhagidial organ II, dorsal aspect; (E) subcapitulum, ventral aspect; (F) palpus, lateral aspect; (G) apex of tarsus III with oar-like iteral (it) setae, lateral aspect.

Figure 12. Troglocheles christiani sp. nov., adult female, setal arrangement on legs, lateral aspect; (A) leg I, genu, tibia, tarsus; (B) leg I, trochanter, basifemur, telofemur; (C) leg II; (D) leg III; (E) leg IV; (F) dorsodistal rhagidial Φ1 and spiniform Φ2 solenidion on tibia I; (G) dorsodistal lanceolate Φ1 and spiniform Φ2 solenidion on tibia II, dorsal aspect (ω, Φ, σ and ε designations for solenidia on tarsus, tibia, genu and for famulus, respectively).