Troglocheles aggerata, Zacharda, 2000

Zacharda, Miloslav, 2000, New species of the genus Troglocheles (Acari: Prostigmata: Rhagidiidae) from Oetztal Alps, Tyrol, with a key to adult species of the genus, Journal of Natural History 34 (3), pp. 463-478 : 472-476

Troglocheles aggerata n. sp.

(®gures 4±6)

Material examined

All from Austria, Tyrol, Oetztal Alps, Obergurgl (11ss02¾E, 46ss52¾N). HOLOTYPE: adult female. Collected in pitfall traps at 0.6 m in subterranean spaces of talus slope on the southern slope of Festkogl-mt (4 June 1991 to 6 June 1992); coll. V. RuÊzÏicÏka and M. Zacharda. PARATYPES: two females, same data as holotype; deposited in the Canadian National Collection of Insects and Arachnids, Ottawa, in micropreparations, Type No. 22,407 .

D iagnosis

Prosoma, in comparison with opisthosoma, small, narrow; lateral shoulders of opisthosoma with setae c 2 striking and protruding laterally. Bothridial setae sc 1 short, slightly overlap disjugal suture. Opisthosoma enlarged, ventral epimeres I± IV strikingly small. Dorsal opisthosomal setae c 1, d 1, e 1, f 1 short; insertions of setae f 1 distal to f 2, setae f 1 do not reach insertions of f 2. Chelicera with relatively short and robust digits; ®xed digit ¯attened laterally and broad; masticatory surface of ®xed digit distinctly convex. Rhagidial organs I and II each consist of four separate oblique rhagidial solenidia and famulus positioned laterad of proximal rhagidial solenidion.

D escription

Adult female (three examined). Length of idiosoma 1280±1440 m m. Ratio of leg I length to idiosomal length 0.73±0.93.

Gnathosom a. Subcapitulum slender, oval, subtriangular (®gure 5E); ratio of length to breadth 1.50±1.66; distal hypostomal lips with spiniform internal malar and serrate external malar processes; adoral setae nude; proximal subcapitular setae ciliate, external pair slightly longer than internal pair. Chelicerae slender, robust, dorsal surface with distinct saddle-shaped depression distal to level of bases of digits (®gure 5A); cheliceral digits long and robust; ®xed digit ¯attened laterally and broad, its masticatory surface smooth and with distinct broad convex rim arising opposite insertion of distal cheliceral seta; masticatory surface of movable digit smooth. Chelicerae 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 ®xed digit. Length of chelicera 280±290 m m, dorsoventra l width 109±115 m m, length of movable digit 109±112 m m, length of proximal and distal cheliceral setae 23 and 33±43 m m, respectively, distance between their insertions 26±30 m m. Ratio of cheliceral length to dorsoventral width 2.43±2.57; ratio of length of movable digit to length of chelicera 0.38±0.40; ratio of length of movable digit to dorsoventral width of chelicera 0.97±1.00. Palpus robust, with relatively slender tarsus (®gure 5D); ratio of length to width of tarsus 2.58±3.00. Length of palpal trochanter, femorogenu, tibia and tarsus 33±36, 105±115, 30 ±46 and 99±105 m m, respectively. Number of setae and solenidia (in brackets) on palpal trochanter, femorogenu, tibia and tarsus 0-2-3-10(1), respectively. Two ciliated setae on palpal tibia strikingly short, tarsal solenidion spiniform, erect.

Prodorsum. Naso well-developed, with pair of internal vertical setae v 1. Bothridial setae sc 1 ®liform, ®nely pubescent, relatively short, overlap disjugal suture only slightly (®gure 4A). Setae v 2 strikingly short. Length of setae: v 1 46±49, v 2 30, sc 1 102± 115, sc 2 112±115 m m. Eyes absent.

Opisthosomal dorsum. Complement and arrangement of dorsal setae and cupules typical for Rhagidiidae (®gure 4A); three pairs of cupules; ia positioned laterally at level about midway between setae c 1 and d 1, im lateral and just anterior to setae e 1, ip laterally at level about two-thirds of interval from setae e 1 to f 1. Setae c 1, d 1, e 1, f 1 reach 0.30, 0.26, 0.23±0.26, 0.30 of distance to insertion of successive setae. Setae f 1 strikingly distant from f 2. Length of setae: c 1 46±63, c 2 105±112, d 1 53±59, e 1 59 ± 63, f 1 72±79, f 2 56±59, h 1 112±115, h 2 66±72 m m.

Podosoma. Coxisternal plates (epimeres) I, II, III, IV strikingly small, with 3-1-4-3 ®nely pubescent setae, respectively (®gure 4B).

Genital region. Genital valves each with ®ve ®nely pubescent setae of similar length, 23±30 m m, arranged evenly along medial edge of valve (®gure 4B). Five pairs of aggenital (paragenital) setae of similar length, 33±36 m m. Length of genital valves 132± 148 m m. Cupules ih positioned ventrolaterally, almost laterad of posteriormost pair of adanal setae.

L egs. Leg I 976±1200 m m long, 0.73±0.93 as long as idiosoma. Empodia of all legs setulose, broadly oval in dorsoventral view, slightly longer than claws; claws each with small ventrobasal clawlet. Number of setae (solenidia and famulus e bracketed), respectively, on legs I-II-III-IV are: trochanters 1-1-2-2; basifemora + telofemora 5 +5-5 +5-4 +4-3 +4; genua 10 (1)-7 (1)-6(1)-6; tibiae 12 (2)-7(2)-5 (2)- 5 (1); tarsi 17 (4 + e)-16(4 + e)-14-13 (®gure 6). Genua I and II each with one erect spiniform distoventral solenidion, genu III with one small spiniform dorsoproximal solenidion. Tibia I with one dorsoproximal erect spiniform solenidion, and one dorsodistal rhagidial solenidion; tibia II with one laterodorsal proximal spiniform erect solenidion, and one lanceolate dorsodistal solenidion recessed in a deep pit with a small surface pore; tibia III with two erect spiniform laterodorsal proximal solenidia arranged in tandem; tibia IV with one erect spiniform laterodorsal solenidion. Tarsi II, III, IV each with two distolateral oar-like ciliated subapical setae (®gure 5F). Tarsus I slender, its tip abruptly truncated in lateral view, length to width ratio 4.87±5.64, with four rhagidial solenidia lying obliquely in separate depressions, stellate famulus e inserted antaxially laterad of ®rst proximal rhagidial solenidion (®gure 5B). Tarsus II with four rhagidial solenidia in separate oblique depressions and small spiniform famulus e inserted antaxially laterad of ®rst and second proximal solenidion (®gure 5C).

A nities

T. aggerata n. sp. di ers from other known Troglocheles species in (1) the proportions of prosoma and opisthosoma, (2) relatively smaller epimeres I± IV, (3) the morphology of the chelicera with the robust ¯attened ®xed digit.

Etymology

The name aggerata means inhabiting talus slopes, and this reēcts the habitat where this species was discovered. Feminine gender.

Remarks

Troglocheles aggerata n. sp. was only collected in spaces between talus fragments in a cool and moist talus slope in the alpine subnival zone of the Oetztal Alps. The occurrence of this species seems to be con®ned to this biotope. Speci®c morphological adaptations such as (1) the loss of eyes; (2) the extremely ®ne whitish integument; (3) relative reduction of the prosoma and legs; (4) relative enlargement of the opisthosoma can be viewed as characters that suggest movement in con®ned spaces, i.e. edaphic or hemiedaphic habitats. They resemble edaphomorphism s as introduced by Zacharda (1979) and broadly discussed by Lindquist and Palacios-Vargas (1991). In the light of these derivative modi®cations T. aggerata represents a derivative lineage adapted to special environmental conditions in con®ned spaces between fragments of the alpine talus slope.