Rhagodes is a wide-spread genus of Camel Spiders distributed from north to east Africa, and through the Middle East to central Asia. It is the largest genus in the family Rhagodidae, with 25 described species worldwide. With seven species, the highest species diversity of the genus Rhagodes occurs in Iran. The genus Rhagodes is mainly known from east of the country, where five species are represented. Rhagodes ahwazensis was the first occurrence of the genus from the western regions of Iran. Otto Kraus described the holotype of Rhagodes ahwazensis based on a male from southwest Iran in 1959. He provided a brief description and characterised the species by considering the presence of bacilli on the coxae of legs I–III, spinulation of legs, and body coloration. There is no taxonomic study or locality record on the species in the literature after the original description.
In a paper published in the journal Arthropoda Selecta on 19 June 2020, Hassan Maddahi of the Department of Biology at the Ferdowsi University of Mashhad, Mansour Aliabadian, also of the Department of Biology, and of the Institute of Applied Zoology at the Ferdowsi University of Mashhad, Majid Moradmand of the Department of Biology at the University of Isfahan, and Omid Mirshamsi, again of the Department of Biology, and the Institute of Applied Zoology at the Ferdowsi University of Mashhad, revise the previously described diagnostic characters of Rhagodes ahwazensis and provide a detailed redescription for both sexes, as well as illustrations of thetype material and a distribution map, and data on sexual dimorphism.
Specimens were collected during field-work to the southwest Iran from April to June 2017 at night by direct searching. All specimens were preserved in 75–80% alcohol and deposited at the Solifugae collection at the Zoological Museum of Ferdowsi University of Mashhad. A specimen from the Arachnid collection of the Zoological Institute of the Russian Academy of Sciences, was also included in the study.
Rhagodes ahwazensis is easily distinguished from closely related species by general coloration. Males of the species can be distinguished from other related congeners based on two characters: (1) flagellum does not cover any portion of the distal tooth on prolateral view of the fixed finger, and (2) no portion of ventral surface of flagellum is visible in retrolateral view of chelicera. Rhagodes ahwazensis can be distinguished from the species Rhagodes eylandti by having larger and more robust chelicerae.
The propeltidium and anterolateral propeltidial lobe of the males are yellowish-brown with brown setae and bristles; lateral margin of anterolateral propeltidial lobe yellow; eyes light brown, ocular tubercle dark grey to black, two small dark brown bristles projecting forward; parapeltidium, mesopeltidium and metapeltidium yellow. Chelicerae do not uniformly colored, dorsally and laterally yellowish- brown to ocher yellow in proximal part, reddish-brown in median part and dark brown in distal part, with two light brown dorsal parallel stripes, ventrally yellow; fingers reddish-brown to dark brown, mucra dark brown to blackish-brown. Pedipalps yellow except for dark brown tarsus and distal portion of metatarsus, with light-brown setae; legs uniformly yellow except for brown to dark brown distal half of tarsus of legs I, with abundant small- to medium-sized yellow to light-brown setae. unguiculus light brown and pedunculus yellow; malleoli white.
The opisthosoma is overall yellow, each opisthosomal tergite with a yellowish-grey rectangle, making a yellowish-grey dorsal longitudinal stripe which ends before 9th tergite, 9th and 10th tergites entirely yellow, anal segment yellow; opisthosoma dorsally and ventrally covered with yellow to light-brown setae, pleura densely covered with dark-yellow setae
When fingers of the chelicerae are closed, the apex of the movable finger terminal tooth reaches the median portion of the fixed finger mucron and the movable finger proximal tooth lies proximal to the fixed finger proximal tooth. The fixed finger with a single row of three median teeth and three series of fondal teeth, the former comprises large fixed finger proximal tooth, fixed finger medial tooth and small fixed finger distal tooth, and the latter includes a row of six retrofondal teeth (3 retrofondal anterior teeth, retrofondal medial tooth, retrofondal submedial tooth, and a relatively large retrofondal proximal tooth), a row of three retrofondal teeth and two to three irregularly-spaced basifondal teeth; fond basally with row of five to six denticles, mostly present on prolateral surface; the movable finger with a single row of median teeth, including large movable finger proximal tooth, small movable finger medial tooth, and a series of prolateral teeth with a small movable finger prolateral tooth and a well-developed movable finger prolateral carina.
The flagella comprise two paraxially immovable, tube-like flagella at the prolateral view of fixed finger. They project forward from the distal end of the row of pvd seta and rise up as high as a quarter of the circle’s perimeter to form a single hornlike flagella (diploflagella). At prolateral view of the fixed finger, flagella do not cover the fixed finger distal tooth. At retrolateral view, ventral surface of flagella is not visible.
The paturon has a longitudinal row of 12 brown, well-developed, regularly-spaced and distally directed prodorsal proximal setae, increasing in length and robustness from proximal to distal, and a row of secondary prodorsal proximal setae; four irregular rows of straight to curved acuminate, distally directed proventral distal setae, except proximal ones close to the interdigital articulation which are plumose in distal half; ventral flagellar seta setae slightly longer than proventral distal setae, curved and distally directed; a row of long acuminate proventral subdistal setae setae; weak, short promedial setae setae sparsely scattered among stridulatory setae; a narrow, longitudinal field of slightly curved, ventrodistally to distally directed proventral setae, increasing in length and thickness distally. The stridulatory apparatus comprises 10 parallel, regularly-spaced and distally directed stridulatory setae, and with 11 stridulatory ridges. The movable finger has a series of straight to slightly curved, dorsodistally directed movable finger prodorsal setae, the apical-most setae is longer; series of straight, ventrodistally directed movable finger proventral setae, distally increasing in length, thickness and curvedness; a narrow field of straight, non-plumose, distally directed movable finger promedial setae. The movable finger fondal setae sare a short series of straight to mostly devoid of plumose setae. In retrolateral view. the paturon has four series of several long, thin, irregularly distributed, distally directed retrolateral finger setae setae, proximal series are longer than the row closest to the teeth; dorsally to dorsodistally directed retrolateral manus setae, covering the rest of retrolateral surface, increasingly becoming more robust and sclerotized from proximoventral to dorsodistal. The movable finger has two longitudinal clusters of retrolateral proximal setae: a dorsal small longitudinal cluster of acuminate to significantly reduced plumose, distally directed retrolateral proximal setae, increasing in length and robustness from proximal to distal part, and a ventral longitudinal cluster of non-plumose retrolateral proximal setae.
Rhagodes ahwazensis has two ventrally located lyriform organs, near the interdigital articulation, and an oval medioventral organ on the ventral margin of the stridulatory plate.
All coxae of first three pairs of legs have long light brown bacilli, which are rather well visible on thMe coxae of legs III. Their number differ among coxae and they are mostly placed at coxae of legs II and III (from 6 to 13 on each coxa).
Tarsus of legs II–IV ventrally without spiniform setae; metatarsus of legs II and III ventrally with 1.2 and metatarsus of legs IV with 1.2.2 spiniform setae; metatarsus of legs II and III dorsally with a series of six brown spiniform setae; tibia of legs II and III with one dorsal apical spiniform setae/.
The genital sternite of adult males has an concave internal margin and sclerotized posterior margin, opercula of the genital sternite with two lobes extended laterally and a central longitudinal opening; posterior half of 3rd and 4th abdominal sternites with two symmetrically located paired spiracles; anal segment hemispherical, longitudinal anal slit entirely located on the ventral surface of the anal segment.
The colouration of females is similar to that of male. Propeltidium and anterolateral propeltidial lobe greyish-brown; chelicerae dorsally and retrolaterally with larger yellowish-brown proximal portion. Pedipalps with reddish-brown metatarsus. First pair of leg with dark-brown tarsus and reddish-brown metatarsus. Opisthosoma ocher yellow with a lighter dorsal longitudinal stripe. Body covered with darker setae than male.
The chelicerae are similar to those of the male. In adult specimens the apex of the movable finger terminal tooth touch the mucra of the fixed finger when fingers are closed. Dentition is similar to that of males. Teeth comparatively larger, especially the fixed finger proximal tooth and movable finger proximal tooth which are markedly enlarged; fixed finger medial tooth and fixed finger distal tooth with different orientation related to other fixed finger teeth and projected ventrodistally to distall; tiny retrofondal submedial tooth.
The paturon is similar to that of the male. With thinner prodorsal proximal setae setae rather than male; four rows of irregularly-spaced plumose proventral distal setae, densely spaced proximally in the proventral distal row close to the interdigital articulation, few distal proventral distal setae are robust, longer and non-plumose; proventral setae are slightly larger than male. The stridulatory apparatus is similar to that of male, with slightly longer stridulatory setae and more extended stridulatory ridges. The movable finger is similar to those of male. Series of plumose, distally directed movable finger prodorsal setae, the apical-most ones longer, slightly curved, non-plumose and dorsodistally directed; acuminate to plumose movable finger promedial setae.
There are 5 to 11 brown prominent bacilli on each coxa of legs I–III in females. Tarsus of legs II–III ventrally with one spiniform seta and tarsus of legs IV ventrally with 1.1 spiniform setae; metatarsus of legs II and III ventrally with 1.1 or 1.2 and metatarsus of legs IV with 1.1.2 spiniform setae; metatarsus of legs II and III dorsally with a series of six brown stout spiniform setae.
The opisthosoma is similar to that of male. Genital sternite with less concave internal margin, opercula of the genital sternite with smaller opening than male.
Rhagodids were mainly described on the basis of a small set of characters, consequently, a large number of species are only known based on inadequate original descriptions. There are dozens of species known from a single sex or from few specimens and their taxonomic identity needs to be re-examined. Moreover, intraspecific variations and sexual dimorphism are rarely studied within the family Rhagodidae. Maddahi et al. have re-described Rhagodes ahwazensis and provided a detailed description of the species, including both sexes.
Intraspecific variation of the male Rhagodes ahwazensis is not significant in contrast to variation seen in males of Rhagodes eylandti. This lack of colour variation may correspond to the narrow distribution range of the former. Rhagodes ahwazensis also showed a low level of sexual dimorphism in comparison to Rhagodes eylandti. The female of Rhagodes ahwazensis is darker than males, with smaller and thicker bacilli, and smaller malleoli. Main sexual differences of the species were seen in the cheliceral characters as below: slightly longer stridulatory setae and more extended stridulatory ridges presented in female; proventral distal setae setae are totally plumose in female except few distal setae; movable inger prodorsal setae, movable finger promedial setae, movable finger fondal setae, and the dorsal clump of retrolateral proximal setae are not plumose or mostly devoid of plumosity in males: The fixed finger medial tooth and fixed finger distal tooth are oriented ventrodistal to distal in female: higher chelicera length/chelicera height and chelicera length/chelicera width ratios in males, representing more robust and broader chelicerae in males.
The number of dorsal apical spiniform setae on the tibia of legs II & III which was frequently used in the identification keys of the Rhagodid species, was previously shown to be a variable, impractical diagnostic character for the species Rhagodes eylandti. In the examined specimens of Rhagodes ahwazensis, significant variation was observed in length, thickness and number of these setae.
The application of tarsal spinulation at the genus level taxonomy of the Rhagodid species is controversial and has been repeatedly criticised. According to Maddahi et al., the number of ventral spiniform setae on the tarsus of legs II–IV was variable among the studied specimens and even between different tarsi of a single specimen.
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