Traegaardhia similis Zacharda, 2010

Zacharda, Miloslav, Fong, Daniel, Hobbs Iii, Horton H., Piva, Erminio, Slay, Michael E. & Taylor, Steven J., 2010, 2474, Zootaxa 2474, pp. 1-64 : 40-44

Traegaardhia similis Zacharda , n. sp. ( Figs 29–31)

Material examined

HOLOTYPE: adult female, U.S.A., Arkansas, Marion Co., Toney Bend Mine No. 2, coll. M.E. Slay, C.J. Bitting, 24.5.2004, deposited in the Museum of Biological Diversity, Ohio State University, Type No. OSAL0007396; paratypes (deposited with the holotype): adult female, Missouri, Pulaski Co. , Davis Cave No. 2, coll. S.J. Taylor, M.E. Slay, 17.6.2004, OSAL0007397; adult female, Missouri, Pulaski Co. , Meyer Cave , coll. S.J. Taylor, M.E. Slay, 13.5.2004, OSAL0007398; adult female, Missouri, Pulaski County , Davis Cave No. 2, coll. S.J. Taylor, M.E. Slay, 17.6.2004, OSAL0007399; adult female, Arkansas, Marion Co. , Morning Star Mine No. 5, coll. M.E. Slay, C.J. Bitting, 26.5.2004, OSAL0007400; adult female, Arkansas, Marion Co. , Saltpeter Cave , 6.6.2004, coll. M.E. Slay, W. Baker, OSAL0007401; Missouri, Pulaski Co. , Davis Cave No. 3, 18.66 km SSW St. Robert, coll. S.J. Taylor, M.E. Slay, 23.10. 2003, OSAL0007402; adult female, Arkansas, Marion Co. , Saltpeter Cave , coll. M.E. Slay, W. Baker, 6.6.2004, OSAL0007403; adult female, Arkansas, Marion Co. , Toney Bend Mine No. 2, coll. M.E. Slay, C.J. Bitting, 24.5.2004, OSAL0007404; adult male, Missouri, Pulaski Co. , Joy Cave , coll. S.J. Taylor, M.E. Slay, 15.6.2004, OSAL0007405; adult male, Missouri, Pulaski Co. , Fort Leonard Wood , Ramsey Cave , 13.84 km SE of St. Robert, coll. S.J Taylor, M.E. Slay, 9.1.2004, OSAL0007406; adult female, Missouri, Pulaski Co. , Davis Cave , coll. S.J Taylor, M.E. Slay, 17.6.2004, OSAL0007365.

Diagnosis

Prodorsal bothridial setae sc 1 about same length as strikingly long v 2. Cheliceral fixed digit with basal lateral fissure located at level of insertion of proximal cheliceral seta; proximal cheliceral seta inserted distad of articulation of cheliceral digits and its tip reaches, or slightly overlaps, insertion of distal seta; cheliceral movable digit serrated along approximately distal half of masticatory surface. Palpal tarsus slightly longer than femorogenu, with ten pubescent setae. Rhagidial organ I comprised of four relatively short rhagidial solenidia (ω) in separate depressions; proximal and distal rhagidial solenidion axial, two medial oblique; stellate famulus (ε) inserted laterad of proximal rhagidial solenidion antiaxially. Rhagidial organ II with three short rhagidial solenidia lying in tandem in confluent depressions; small spiniform famulus (ε) between first and second proximal rhagidial solenidion antiaxially. Coxae I, II, III, IV with 3-1-6-3 finely pubescent setae, respectively; exceptionally coxa III with five setae asymmetrically. Spiniform solenidia on genua I and II (σ) dorsomediodistal and dorsomedial, respectively. Neotrichy in genital region: seven to nine pairs of aggenital setae.

Affinities

Adults of T. similis n. sp. partly resemble those of Rhagidia gelida Thorell, 1872 particularly in the neotrichy of the genital region and in the uncommon dorsal position of tiny spiniform solenidia (σ) on the genua I, II and III. Similarly, the dorsal spiniform solenidia on the genua III are also in T. cavernarum , T. distisolenidiata T. gracilis , T. holsingeri and T. nasuta , but in these species the spiniform solenidia on the genua I and II are ventral.

T. similis n. sp. and R. gelida differ in many morphological characteristics such as (1) in Traegaardhia similis the proximal cheliceral seta is inserted distad of articulation of cheliceral digits whereas in R. gelida it is inserted above this articulation; (2) in T. similis the distal cheliceral seta is inserted slightly laterally whilst in R. gelida it is inserted dorsally; (3) in T. similis the basal part of the masticatory surface of the fixed digit is without prebasal lobe whereas in R. gelida the basal part of the fixed digit is enlarged and with the prebasal lobe which is typical of many representatives of the genus Rhagidia ; (4) in T. similis the rhagidial solenidia (ω) in the rhagidial organ I lie in four separate depressions whereas in R. gelida these rhagidial solenidia lie in confluent depressions; (5) in T. similis the neotrichy occurs only in the genital region whereas in R. gelida the neotrichy occurs not only in the genital region, but also on the coxae III and IV and on the palpal tarsus.

Etymology

The specific epithet similis means similar in Latin and it reflects several similarities between the different species R. gelida and T. similis . Feminine gender.

Description

Adult female (nine examined). Length of idiosoma 1250(1040–1440) µm. Ratio of leg I length to idiosomal length 1.42(1.22–1.78).

Gnathosoma . Subcapitulum moderately slender, oval ( Fig. 30G); ratio of length to breadth 1.13(1.07– 1.23); distal subcapitular lips with spiniform internal and serrate external malar processes; adoral setae nude; proximal subcapitular setae pubescent, external pair slightly longer than internal pair. Dorsal surface of chelicera with distinct saddle-shaped depression at level of bases of digits ( Fig. 30A,B); fixed digit terminates in two cusps, smooth along masticatory surface and without large, distinct prebasal lobe; prebasal lateral fissure located at level of insertion of proximal cheliceral seta; movable digit serrated along approximately distal half of masticatory surface. Chelicera with two setae; proximal seta inserted slightly distad of articulation of movable digit; tip of proximal seta reaches or slightly overlaps insertion of distal seta; tip of distal seta overlaps apex of fixed digit. Length of chelicera 281(247–323) µm, dorsoventral width 115(99–142) µm, length of movable digit 111(99–125) µm, length of proximal and distal cheliceral setae 30(28–33) and 64(59–69) µm, respectively, distance between their insertions 28(23–36) µm. Ratios: cheliceral length to dorsoventral width 2.44; length of movable digit to length of chelicera 0.39(0.36–0.43); length of movable digit to dorsoventral width of chelicera 0.96(0.88–1.06). Palpal tarsus longer than femorogenu ( Fig. 30F); ratio of length to width of tarsus 4.20(3.71–4.75). Length of palpal trochanter, femorogenu, tibia and tarsus 53(46–59), 159(142– 165), 81(66–92) and 176(158–198) 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, erect, positioned laterodorsally at mid length of palpal tarsus.

Prodorsum. Naso well-developed, with pair of internal vertical setae v 1 ( Fig. 29A). Bothridial setae sc 1 filiform, finely pubescent, about same length as strikingly long v 2. Length of setae: v 1 81(72–89), v 2 168(152– 165), sc 1 152(125–165), sc 2 208(198–214) µm.

Opisthosomal dorsum and anal region. Cupules ia positioned laterally between setae c 1 and d 1; im laterally between setae d 1 and e 1; ip slightly laterodistad of setae f 2; ih positioned ventrolaterally, laterad of insertions of adanal setae ad 1 ( Fig. 29A,B). Length of setae: c 1 110(99–122), c 2 231, d 1 103(89–112), e 1 103(89– 112), f 1 136(122–148), f 2 77(69–82), h 1 176(158–195), h 2 100(79–115), ps 1 138(132–148), ps 2 83(79–86), ps 3 76(72–79), ad 1 70(66–75) µm.

Podosoma. Coxae I, II, III, IV with 3-1-6-3 finely pubescent setae, respectively; exceptionally coxa III with five setae asymmetrically.

Genital region. Genital valves each with five finely pubescent genital setae (g) of similar length, about 45(30–56) µm, arranged evenly along internal lateral edge of valve ( Figs. 29B, 30E). Neotrichy of aggenital setae (ag) of similar length, about 95(72–112) µm. Number of aggenital setae variable, i.e., eight or nine pairs of aggenitals symmetrically or seven/nine, eight/nine, eight/ten, nine/ten aggenitals asymmetrically flank genital valves. Length of genital valves 187(156–247) µm.

Legs. Leg I 1580 (1552–2000) µm long, about 1.42(1.22–1.78) as long as idiosoma. Empodia of all legs setulose, slightly longer than claws; claws each with small clawlet (basal spur) ventrobasally. Number of setae and solenidia (solenidia and famulus (ε) bracketed), respectively, on legs I-II-III-IV ( Fig. 31): trochanters 1-1- 2-2, basifemora+telofemora 5+5-6+5-4+5-3+4, genua 11(1)-9(1)-7(1)-6, tibiae 11(2)-7(2)-7(2)-6(1), tarsi 19(4+ε)-16(3+ε)-14-14. Genu I with one erect spiniform dorsomediodistal solenidion (σ); genu II with one erect spiniform dorsomedial solenidion; genu III with one small erect spiniform dorsomedial solenidion. Tibia I with.one small erect spiniform dorsoproximal solenidion (Φ), and one dorsodistal rhagidial solenidion; tibia II with one erect spiniform dorsoproximal solenidion, and one lanceolate dorsodistal solenidion recessed in deep pit with long slot-shaped surface pore ( Fig. 31E); tibia III with two small erect adjacent spiniform dorsoproximal solenidia; tibia IV with one erect spiniform laterodorsal proximal solenidion. Tarsus I slender, its tip slightly tapers in lateral view; ratio length to width of tarsus I 7.11(6.20–8.00). Rhagidial organ I comprised of four short rhagidial solenidia (ω) lying in separate depressions, proximal and distal solenidion axial, two medial oblique; stellate famulus (ε) laterad of proximal rhagidial solenidion antiaxially ( Fig. 30C); tarsus II with three rhagidial solenidia lying in tandem in confluent depressions and small spiniform famulus (ε) inserted laterad of second proximal solenidion antiaxially ( Fig. 30D).

Adult male (two examined). Smaller than female, length of idiosoma 1016(960–1072) µm; club-shaped sperm sac showing through the opisthosomal integument. Otherwise as in female.

Remarks

Traegaardhia similis is one of the most common rhagidiid mites in caves of the Ozark karst area. However, no distinct troglomorphisms typical of troglobiotic Rhagidiidae are discernible in this species except the elongated palpal tarsus which is a bit longer than the femorogenu. Normally in the epigean, hypolithic and particularly edaphomorphic rhagidiids the palpal tarsus is usually the same lenght as, or shorter than, femorogenu. In the Ozarks, this species is probably troglophilous and eventually may be found also outside of caves, most probably in the mesovoid shallow substratum.