Troglocheles quinquesolenidiata 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 : 643-649

Troglocheles quinquesolenidiata Zacharda , sp. nov.

( Figures 2–5 )

Material examined

Holotype. Adult female, Italy, Veneto, Gruppo del Carega-Piccole Dolomiti-Pasubio, Recoaro Terme (Vicenza), Buso Brutto Cave (1793 V / VI), 918 m a.s.l., coll. G. Peretto and E. Piva, 1 September 1996, deposited in the Museum of Biological Diversity , Ohio State University, Type No. OSAL0007410 .

Paratypes. Deposited with the holotype; three adult females, same data as holotype , OSAL0007411 , OSAL0007412 , OSAL0007413 .

Diagnosis

Rhagidial organ I comprises five rhagidial solenidia lying obliquely in separate depressions; rhagidial organ II with four rhagidial solenidia lying in separate oblique depressions, and small spiniform famulus (ε) inserted between first and second proximal rhagidial solenidia antiaxially. Spiniform solenidia on tibiae I, II and III minute. Tibia IV with one minute spiniform dorsal medioproximal solenidion. Ratio of tarsus I length to dorsoventral width 7.55; ratio of palpal tarsus length to dorsoventral width 5.23 (5.0–5.4). Bothridial setae sc 1 overlapping insertions of opisthosomal setae c 1.

Description

Adult female (four examined). Length of idiosoma 900 (800–1008) µm. Ratio of leg I length to idiosomal length 2.10 (1.96–2.28).

Gnathosoma . Subcapitulum slender, oval ( Figure 3F ), subtriangular, ratio of length to breadth 1.33–1.82; distal hypostomal lips with spiniform internal malar and 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

A,B

to level of bases of digits; cheliceral digits strikingly long, slender; fixed digit terminates in two cusps, smooth along masticatory surface and with small lateral fissure at level of bases of digits ( Figure 3A ); movable digit smooth along masticatory surface. Chelicera with two setae inserted distad of articulation of movable digit; tip of proximal seta not reaching insertion of distal seta; tip of distal seta slightly overlaps apex of fixed digit. Length of chelicera 316 µm, dorsoventral width 109 µm, length of movable digit 162 (155–165) µm, length of proximal and distal cheliceral setae 18 (16–20) and 59 (53–63) µm, respectively, distance between their insertions 20–23 µm. Ratios: cheliceral length to dorsoventral width 2.75–2.96; length of movable digit to length of chelicera 0.51; length of movable digit to dorsoventral width of chelicera 1.42–1.51.

A,F B,C D G / E

Palpal tarsus shorter than femorogenu ( Figure 3G ); ratio of length to width of tarsus 5.23 (5.0–5.4). Length of palpal trochanter, femorogenu, tibia and tarsus 40 (33–43), 217 (198–231), 62 (59–66) and 178 (175–181) 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, erect.

Prodorsum. Naso well-developed ( Figure 2A ), with pair of internal vertical setae v 1. Bothridial setae sc 1 filiform, finely pubescent, overlapping insertions of opisthosomal

setae c 1. Length of setae: v 1 86 (73–92), v 2 53 (46–59), sc 1 130 (122–148), sc 2 126 (119–139) µm.

Opisthosomal dorsum and anal region. Cupules ia positioned proximad of c 2, laterally between setae c 1 and d 1, im lateral to setae e 1, ip slightly distad and laterad of setae f 1, ih positioned ventrolaterally, laterodistad of adanal setae ad 1 ( Figure 2A ). Setae c 1, d 1 reach about two-thirds of distance to insertion of next seta, seta e 1 reaches about one-third of distance to insertion of f 1, seta f 1 reaches about to insertion of h 1. Length of setae: c 1 65 (59–73), c 2 147 (142–155), d 1 69 (66–73), e 1 70 (63–73), f 1 109 (96–132), f 2 61 (53–66), h 1 129 (119–138), h 2 73 (69–79), ps 1 74 (66–82), ps 2 55 (46–59), ps 3 40 (39–41), ad 1 62 (60–63) µm.

Podosoma. Coxae I, II, III, IV with 3-1-5-3 finely pubescent setae, respectively ( Figure 2B ).

Genital region. Genital valves each with five finely pubescent genital setae (g) of similar length, about 26 µm, arranged evenly along medial edge of valve. Five pairs of pointed aggenital (ag) setae of similar length, about 66 (53–76) µm. Length of genital valves 141 (135–148) µm.

Legs. Leg I 1892 (1824–2032) µm long, about 2.10 (1.96–2.28) times as long as idiosoma. Empodia of all legs setulose, longer than claws, no ventrobasal clawlets on claws. Trochanters I strikingly elongated. Tarsus II, III, IV each with oar-like subapical setae typical of Troglocheles ( Figure 3D ). Number of setae and solenidia [solenidia and famulus (ε) bracketed], respectively, on legs I-II-III-IV ( Figures 4 , 5 ): trochanters 1-1-2-2; basifemora + telofemora 4+5-6+5-4+4-3+4; genua 14(1)-8(1)-5(1)-6; tibiae 11(2)-7(2)-6(2)-5(1); tarsi 17(5+ ε)-17(4+ ε)-16-15. Spiniform solenidia on leg segments very small. Genua I and II each with one erect spiniform distoventral solenidion (σ); genu III with one small spiniform medioventral solenidion. Tibia I with one erect spiniform dorsodistimedial solenidion (Φ), and one dorsodistal rhagidial solenidion; tibia II with one spiniform erect dorsomedial solenidion, and one lanceolate dorsodistal solenidion recessed in deep pit with small surface pore ( Figure 3E ); tibia III with two adjacent erect spiniform dorsomedial solenidia; tibia IV with one erect spiniform dorsoproximal solenidion. Tarsus I slender, its tip slightly tapers in lateral view, ratio length to width 7.55, with five rhagidial solenidia (ω) lying obliquely in separate depressions dorsodistally ( Figure 3B ), stellate famulus (ε) subtending the second proximal rhagidial solenidion antiaxially; tarsus II with four rhagidial solenidia lying in separate oblique depressions ( Figure 3C ), and small spiniform famulus (ε) inserted between the first and second proximal rhagidial solenidion antiaxially.

Affinities

Troglocheles quinquesolenidiata sp. nov. belongs to the strasseri species group because it has 3-1-5-3 setae on coxae I-II-III-IV, respectively, the spiniform solenidion on tibia I is positioned dorsomedially and the distance between insertions of the cheliceral setae on the fixed digit is almost the same as the length of the proximal cheliceral seta.

Troglocheles quinquesolenidiata sp. nov. is very similar to T. archetypica from which it can be distinguished by the following principal characteristics. (1) The rhagidial organ I comprises five rhagidial solenidia; in T. archetypica only four rhagidial solenidia are in the rhagidial organ I. (2) Tibia IV with one minute spiniform dorsal medioproximal solenidion; in T. archetypica the spiniform solenidion on tibia IV is absent. (3) The ratio of leg I length to idiosomal length is 2.10 (1.96–2.28); in T. archetypica the ratio of leg I length to idiosomal length is 0.8–1.36. (4) The ratio of tarsus I length to width is 7.55 (6.90–7.70); in T. archetypica the ratio of tarsus I length to width is only 4.41–4.72. (5) The ratio of palpal tarsus length to width is 5.23 (5.0–5.4); in T. archetypica the ratio of palpal tarsus length to width is 2.7–3.0.

Troglocheles quinquesolenidiata sp. nov. is also similar to T. vandeli from which it can be distinguished by the following principal characteristics. (1) The rhagidial organ I comprises five rhagidial solenidia; in T. vandeli only four rhagidial solenidia are in the rhagidial organ I. (2) The spiniform solenidia on tibiae I, II and III are short, minute; in T. vandeli they are strikingly long. (3) The two dorsomedial spiniform solenidia lying in tandem on tibia III are of the same length; in T. vandeli the proximal solenidion is conspicuously longer than the distal one. (4) The spiniform famulus (ε) in the rhagidial organ II is positioned laterad of the proximal rhagidial solenidion; in T. vandeli it is proximal, subtending the proximal rhagidial solenidion. (5) The prodorsal bothridial setae sc 1 overlap insertions of opisthosomal setae c 1; in T. vandeli they overlap the disjugal suture only slightly.

Etymology

The epithet quinquesolenidiata reflects five rhagidial solenidia in the rhagidial organ I which is a unique morphological character in the genus. Feminine gender.

Remarks

Troglocheles quinquesolenidiata sp. nov., having a higher number of solenidia in rhagidial organ I and relatively elongated appendages, is evidently morphologically adapted to life in the subterranean habitat whereas T. archetypica is an epigeic free-living mite that lacks these morphological adaptations. For further details one may consult the discussion in Zacharda (2000), where the phylogenetic relationships between species of the genus Troglocheles are also discussed. In light of our current knowledge about the known Troglocheles species , T. quinquesolenidiata sp. nov. together with T. vandeli are morphologically intermediate between the epigean T. archetypica and the troglobitic representatives of the strasseri species group inhabiting solely caves in the Alps. However, actual phylogenetic relationships between these taxa are not known.

Figures

Figure 2. Troglocheles quinquesolenidiata sp. nov., adult female; (A) dorsum; (B) venter (for setal notation see Description).

Figure 3. Troglocheles quinquesolenidiata sp. nov., adult female; (A) chelicera, lateral aspect; (B) rhagidial organ I, dorsal aspect; (C) rhagidial organ II, dorsal aspect; (D) apex of tarsus III with pubescent oar-like iteral (it) setae, lateral aspect; (E) dorsodistal lanceolate solenidion (Φ) on tibia II; (F) subcapitulum, ventral aspect; (G) palpus, lateral aspect.

Figure 4. Troglocheles quinquesolenidiata sp. nov., adult female, setal arrangement on legs, lateral aspect; (A) leg I; (B) leg II (ω, Φ, σ and ε designations for solenidia on tarsus, tibia, genu and for famulus, respectively).

Figure 5. Troglocheles quinquesolenidiata sp. nov., adult female, setal arrangement on legs, lateral aspect; (A) leg III; (B) leg IV (Φ, σ designations for solenidia on tibia and genu, respectively).