Description of the Postlarval Stages of Dactylochelifer gracilis Beier, Pseudoscorpiones: Cheliferidae

1 Department of Entomology, Islamic Azad University, Arak 3836119131, Iran 2Department of Terrestrial Zoology, Western Australian Museum, Locked Bag 49, Welshpool DC, WA 6986, Australia 3 Division of Invertebrate Zoology, American Museum of Natural History, 79th Street, Central Park West, New York, NY 10024-5192, USA 4Department of Entomology, California Academy of Sciences, Golden Gate Park, San Francisco, CA 94103-3009, USA 5 School of Animal Biology, University of Western Australia, Crawley, WA 6009, Australia


Introduction
Pseudoscorpions are small arachnids usually 2-8 mm in length (e.g., [1]).They are generally confined to habitats such as leaf litter, under stones, under trees or log barks, bird's nests, and mammal's lairs (e.g., [2]).Their life cycle is ovoviviparous and consists of four phases (e.g., [3]): (1) eggs which are attached to the female's abdomen and carried by her in a brood sac, (2) two larval instars that also remain in the brood sac, (3) three nymphal instars, and (4) adults.Nymphs are very similar to adults but are smaller (Figures 8, 9, and 10) and lack genital organs (Figure 11).The three nymphal instars are termed protonymph, deutonymph, and tritonymph and can be easily recognized by the unique number of trichobothria of each stage [4].In addition to the differences in the sexual organs, adult females are generally slightly larger than males.
The present study is focused on the external morphology of the postlarval stages of a species of Dactylochelifer Beier from Iran.This genus is a member of the family Cheliferidae [5,6], which belongs to the Cheliferoidea along with Atemnidae, Chernetidae, and Withiidae [7,8].Dactylochelifer is widely distributed in the Holarctic region [6] and can be recognized by the following combination of features: presence of coxal sacs situated within the coxae of the fourth pair of legs of males, each sac with a well-developed atrium (Figure 7(a)); tarsus with simple subterminal seta (Figures 7(c) and 7(d)); presence of a median seta on each half tergite; tarsal claws not divided; and female with one cribriform plate (Figure 11(e)) [9].
There are currently 44 species belonging to the genus Dactylochelifer of which 28 are represented in the Middle East and Central Asia [6].Although many Asian species are poorly known with brief published descriptions and few illustrations, recent revisionary work on the Central Asian fauna (e.g., [9,13]) has helped clarify the status and distribution of several species.The present study was designed to complement previous work by providing detailed descriptions of all postembryonic life stages of a species of Dactylochelifer found in Kerman Province, Iran.

Material and Methods
The 68 specimens utilized in this study were collected from three sites in Kerman Province, Iran.Specimens were separated from dry leaf litter using a sieve.They were preserved in 70% ethanol and prepared for study as follows.The pedipalps and chelicera, first and fourth legs were dissected, cleared with 60% lactic acid, and mounted on glass microscope slides in Hoyer's medium (a mixture of distilled water, chloral hydrate, Arabic gum, and glycerin).The duration of the clearing phase was dependent on the degree of sclerotization.The specimens were examined and illustrated with an Olympus BH-2 compound microscope and drawing tube attachment.All specimens are lodged in collection of the Acarology Laboratory, Shahid Bahonar University of Kerman (SBUK), Iran.

Taxonomic Results
The specimens used in this study were compared with published descriptions of all species of Dactylochelifer.They compare very favorably with several Asian species of Dactylochelifer.However, they are most similar to D. gracilis Beier, 1951, which was described from a single male collected from an unspecified locality in Kerman Province, Iran, as part of the Österreichischen Iran-Expedition 1949/1950 [11].Although the expedition collected at multiple sites within Kerman Province (e.g., [11,16]), there is, regrettably, no precise collection site other than the name of the province.The specimens used in this study also come from Kerman Province.
This species was later reported from Turkey [17,18], but no further morphological records or descriptions have been published.The morphology of the male tarsus I and tarsal claws is similar to that of some other Asian species of the genus, including D. brachialis Beier, 1952, originally described from Afghanistan [19], but later recorded throughout Central Asia (e.g., [9,13,20]).Dactylochelifer changaiensis was described by Krumpál and Kiefer [21] from male and female specimens collected in Arkhangai Province, Mongolia, and treated as a junior synonym of D. brachialis by Dashdamirov and Schawaller [9], who noted similarities in the shape of the male tarsus I.While the published descriptions of D. gracilis, D. brachialis, and D. changaiensis suggest that they are all very similar to each other, we refrain from making any further taxonomic changes until a more detailed study of variation across a wide range of samples can be undertaken.So, we, therefore, attribute the Iranian material to D. gracilis with reference to geographical characters of previous reports [11].
The specimens reported in this study are slightly larger than the dimensions reported for the holotype of D. gracilis by Beier [11].For example, the pedipalpal femur of the male holotype of D. gracilis was reported to be 0.66/0.16mm [11], whereas the males used in this study are 0.85-1.06/0.20-0.23 (male) and 0.92-1.18/0.22-0.26mm (female).

Material Examined
The materials collected for examination from Iran: Kerman Province were as follows:

Diagnosis
Dactylochelifer gracilis can be readily identified by the shape of male genital organ (Figure 11(d)), the ratio of male tarsus I (2.00-2.30),and the shape of male tarsus I (Figure 7(c)), that is, robust and highly modified with a distinct dorsal indentation and subdistal concavity.are modified and made anterior operculum and posterior operculum; sternites IV to XI are divided by narrow median line; sternal setae simple and longer than tergal setae; sternite X and XI with 2 long tactile setae; and sternal chaetotaxy is shown in Table 3.

Description
Pleurite.It is present as follows: striated; posterior spiracles larger than anterior pairs; tracheae normal; and anus situated between last tergite and last sternite, with 4 circum-anal setae.
Chelicera.It is present as follows: light brown, lighter in color than legs, base of movable finger darker than hand; hand slightly granulate; hand with 5 simple setae; rallum with 3 blades, distal blade longest, with lateral denticulations; serrula exterior with 17-21 blades; serrula interior button like with external ridges; galea with 1-3 distal rami; fixed finger with 6 teeth, 3 terminal acute teeth, and 3 basal teeth large and blunt; and movable finger with galeal seta, these teeth are larger and stouter than teeth of tritonymph and slightly smaller than teeth of female.
Pedipalps.They are present as follows: larger and stouter than tritonymph, distinctly shorter, and slightly narrower than female; dark brown, darker than carapace, chela slightly darker than femur and patella; granulate; most pedipalpal setae short with 1 lateral and few terminal denticulations; chelal fingers and distal base of hand with simple and long setae; trochanter with 2 dorsal projections; femur with distinct pedicel; retrolateral margin of femur slightly curved basally and prolateral margin straight; patella shorter and somewhat wider than femur; femur 1.03-1.11longer than patella; patella with short, distinctly curved pedicel; retrolateral margin of patella distinctly curved basally and prolateral margin slightly curved distally; chelal hand less granulate than pedicel; chela with distinct and moderate pedicel; movable finger shorter than hand with pedicel; hand  to ist than it, eb-esb-ib-isb aggregated basally; movable finger with trichobothrium st situated between t and sb, sb situated close to b; fixed finger with 43-50 and movable finger with 45-52 similar-shaped teeth; and nodus ramosus present in both fingers, clearly longer in movable finger than fixed finger, situated slightly anterior to st in movable finger, and between est and it in fixed finger.
Legs.They are present as follows: leg I: light brown, lighter in color than body; trochanter weakly granulate; femur slightly granulate, stouter than patella and joint widely; patella granulate and longer than femur; patella 1.23-1.37longer than femur; tibia granulate, slightly shorter and narrower than patella, prolateral margin curved distally; tarsus much stouter and larger than in tritonymph, clearly shorter and stouter than in female; tarsus modified, stout and smooth, 1.00-1.04longer than patella; tarsus clearly shorter than tibia, with small granules; most setae with one lateral and a few terminal denticulations; tarsus with simple distal setae and 2 pseudotactile setae; subterminal setae curved; claws symmetric, without teeth; and arolium simple and shorter than claws.

Distribution
Dactylochelifer gracilis has only been recorded from Iran and Turkey [17,18].

Discussion
Many differences are apparent between each stage of D. gracilis, including size, pedipalpal ratios (Table 2, Figures 1   and 2), density of granules on the pedipalps and tergites, and the number of trichobothria on the pedipalpal fingers.The body lengths of deutonymphs are longer than protonymphs and tritonymphs are longer than deutonymphs.Male body lengths are shorter than females.The carapace of protonymphs is slightly longer than wide whereas in the other stages, it is noticeably longer than wide (Figures 3(b The body and carapace of protonymphs are smooth and poorly sclerotized.The sclerotization of the body and carapace begins at the deutonymphal stage and increases gradually to adults.Males are more sclerotized and granulated than females (Figure 8).
The ratios and the degree of granulation of the pedipalps increase during development.Protonymphs have small and International Journal of Zoology smooth pedipalps.The pedipalpal femur of protonymphs is without an obvious pedicel and is 1.21-1.56times shorter than that of deutonymphs.The tritonymphs have stouter and longer pedipalps than deutonymphs, and adults have the longest and widest pedipalps.The pedipalps of males are slightly shorter and thinner than females but they are more granular and slightly stouter (Figure 9; Table 1).
The chela and the leg I gradually become longer (Figures 1  and 2).The chelae of deutonymphs are 1.24-1.49times longer than those of protonymphs and the chelae tritonymphs are 1.23-1.66times longer than those of deutonymphs.The chelae of males are 1.23-1.54times longer than those of tritonymphs but 1.10-1.35times shorter than those of females (Figures 1  and 10).
By comparing tergal and sternal chaetotaxy, a fair deference was confirmed between D. gracilis, D. latreilli, and D. vtoromi.The most important differences can be distinguished by consideration of anterior operculum.The more setae can be counted on anterior operculum of D. latreilli which are measured more than 50 for males and more than 25 for females, the numbers less than what are mentioned before will belong to one of the three mentioned species.Tergal setae is arranged widely variable, but the most tergal setae (20 setae) may be counted in D. gracilis.Tergal chaetaxy of nymphal stages are very similar in all three mentioned before species.It is worth mentioning that there are small differences confirmed in sternal chaetotaxy of nymphal stages, where the most cleared difference is being recognized in protonymphs of D. gracilis which can be identified by presence of 2 setae on sternite IV but there are 4 setae on Sternite IV of D. latreili and D. vtoromi protonymphs.
The sequence of the appearance of individual trichobothria on the fixed and movable fingers during development of pseudoscorpions has been well documented (e.g., [4,7]).The developmental sequence in D. latreillii and D. vtorovi is identical to the pattern of D. gracilis [24,25].

Figure 2 :
Figure 2: Tarsus I L/W of all postlarval stages of Dactylochelifer gracilis.
) and 10(a)).The deutonymphs of both species carry six trichobothria on the fixed finger and two trichobothria on the movable finger.The trichobothria added at this stage are International Journal of Zoology 0

Table 2 :
The ratios of morphological characters in Dactylochelifer gracilis.

Table 3 .
Sternites.They are present as follows: sternite II without setae or lyrifissures; sternite X and IX with 2 long medial setae and 2 short lateral setae; sternal setae simple and longer than tergal setae; sternites not divided; and sternal chaetotaxy is shown in

Table 3 .
Pleurite.It is present as follows: striated and spiracle equal in size.Chelicera.It is present as follows: light brown; hand with 4 setae; galea with 3 or 4 distal rami; rallum with 3 blades; serrula exterior with 11-12 blades; movable finger without galeal seta; and fixed finger with 5 teeth, 2 small and acute terminal teeth, and 3 large and blunt basal teeth.
Pedipalps.They are present as follows: brown; darker than carapace; femur, patella, and chela not granulate; trochanter, femur, and patella with short setae with terminal denticulations; chelal fingers and terminal base of hand with simple setae; trochanter with one dorsal projection; surface of projection granulate; femur without pedicel; retrolateral margin of femur projected; patella shorter and somewhat wider than femur; femur 1.11-1.30longerthanpatella;prolateralmargin of patella convex; movable finger as long as hand with pedicel; fixed finger with 3 trichobothria and movable finger with 1 trichobothrium; fixed finger with 29-31 and movable finger with 32-33 teeth; and nodus ramosus present in both fingers, slightly longer in movable finger than fixed finger, situated medially in movable finger and posterior to et in fixed finger.Legs.They are present as follows: leg I: trochanter not granulated, with 1 seta; femur, patella, tibia, and tarsus not granulate; setae arranged same as adults; femur joined widely with patella; and patella 1.15-1.40longerthanfemur.Leg IV: trochanter not granulated, with 0-1 seta; patella, tibia, and tarsus not granulate; setae arranged same as adults; tibia as long as patella; and patella 1.66-1.75longerthanfemur.6.2.Deutonymph: Figure4, Tables1, 2, and 3Carapace.It present as follows: light brown; lighter in color than deutonymph, darker than abdomen; lateral margins darker and granulate with small granules; longer than wide; with 2 distinct eyes situated very close to anterior margin, completely swell; setae short with terminal denticulations; anterior margin narrower than posterior margin; 2 transverse furrows present; anterior furrow situated medially, narrow, and extending to lateral margins; and posterior furrow shorter, wider, and slightly V-shaped medially.Tergites.They are present as follows: more sclerotized than protonymph; lighter in color than carapace, mostly cream with dark spots; most setae short with terminal denticulations; tergites VII to XI with longer median setae; tergite XI with 2 very long and simple tactile setae; tergites I and II divided with narrow median line; tergites X and XI not divided; and tergal chaetotaxy is shown in

Table 3 .
Sternites.They are present as follows: pale brown; not granulate; sternites X and XI with 2 long median tactile setae; sternal setae simple and longer than tergal setae; and sternal chaetotaxy is shown in

Table 3 .
Pleurite.It is present as follows: striated; spiracles equal in size; and anus situated between last tergite and last sternite.situatedirregularly,tergites I to III with serial setae (in one row), each half-tergite of segments IV to X with 1 median seta, tergite XI with dispersed setae; tergites I-IX divided by narrow median line; tergites X and XI not divided; and tergal chaetotaxy is shown in Table3.
Pedipalps.They are present as follows: larger and stouter than protonymph; brown; darker than carapace; trochanter, femur, patella, and chelal hand slightly granulate; most pedipalpal setae short with terminal denticulations; chelal fingers and base of hand with simple setae; trochanter with a dorsal projections; femur with short pedicel; retrolateral margin of femur semiswollen; prolateral margin of femur more granulate than retrolateral margin; patella shorter and somewhat wider than femur; prolateral margin of patella slightly swollen and more granulate than retrolateral margin; femur 1.10-1.17longerthanpatella; chela weakly granulate; chela less granulate than femur; movable finger as long as or slightly shorter than hand with pedicel; hand 1.02-1.17longerthanmovable finger; fixed finger with 6 and movable finger with 2 trichobothria; fixed finger with 32-35 and movable finger with 34-36 teeth; and nodus ramosus present in both fingers, longer in movable finger than fixed finger, situated posterior of t in movable finger, and between et and est in fixed finger.Legs.They are present as follows: leg I: stouter than protonymph; not granulate; setae arranged same as adults setae; patella 1.20-1.36longerthan femur; and femur joined widely with patella.Leg IV: stouter than protonymph; not granulate; setae arranged same as adults setae; and patella 1.88-2.15longerthan femur.Tergites.They are present as follows: more sclerotized and granulate than deutonymph; lighter in color than carapace, dark cream with 2 brown spots; most tergal setae short with terminal denticulations; tergites IX to XI with longer median setae; and tergite XI with 2 very long and simple tactile setae; tergal setae

Table 3 .
Pleurite.It is present as follows: striated; spiracles equal in size; anus with 4 circum-anal setae; and anus situated between last sternite and last tergite.Chelicera.It is present as follows: light brown, darker in color than legs; dorsal side of movable finger darker than hand; galeal seta present; hand with 5 simple setae; external seta longer than fixed finger; galea with 3 to 5 distal rami; rallum with 3 blades; serrula exterior with 14-17 blades; and fixed finger with 6 teeth, 3 terminal teeth small and acute, and 3 basal teeth large and blunt, these teeth are as large as those of deutonymph.anterior to est, eb-esb-ib-isb aggregated basally; movable finger with trichobothrium st situated between t and sb, sb situated close to b; fixed finger with 44-50 and movable finger with 45-54 similar-shaped teeth; and nodus ramosus present in both fingers, clearly longer in movable finger than fixed finger, situated slightly posterior to st and st in movable finger, and between est and ist in fixed finger.
Pedipalps.They are present as follows: larger and stouter than deutonymph; brown, darker than carapace; lateral margins dark brown; trochanter, femur and patella granulate; chelal hand weakly granulate; most setae short with terminal denticulations; chelal fingers and distal base of hand with 6.4.Female: Figure6; Tables1, 2, and 3Carapace.It is present as follows: dark brown, darker than other stages; less granulate than male; distinctly longer and Sternites.They are present as follows: sternites III to X are divided by narrow median line; sternite XI not divided; sternites II and III are deformed and made anterior operculum and posterior operculum; cribriform plate single, brown in color with darker borders, bean-like in shape; sternal setae simple and longer than tergal setae; and sternal chaetotaxy is shown in Table3.Pleurite.It is present as follows: striated; spiracles equal in size; and anus between last tergite and last sternite, with 4 circum-anal setae.withdistinctandmoderate pedicel; movable finger shorter than hand with pedicel; hand 1.14-1.27longerthanmovablefinger; fixed finger with 8 trichobothrium and movable finger with 4 trichobothrium setae or fixed finger with 8 and movable finger with 4 trichobothrial setae; fixed finger with trichobothrium et situated distal to it, ist situated posterior, and it situated on exterior side of half-tergites and one seta situated on middle zone of each half-tergite; tergite XI with 2 long tactile setae situated laterally; tergites I and XI are not divided; and tergal chaetotaxy is shown in Table3.Sternites.They are present as follows: lighter in color than tergites; less granulate than tergites; sternites II and III