A new species of Charinus Simon 1892 from Brazil, with notes on behavior (Amblypygi, Charinidae)

Abstract A new species of Charinus is described and illustrated from the Brazilian Atlantic Forest. Charinus ruschii sp. n. is found in Santa Lúcia reserve, Espírito Santo state, and is sympatric with Charinus brasilianus and Charinus montanus. The new species can be easily distinguished from the other species of the genus by the combination of the following characters: number of spines on the pedipalp tarsus, size and shape of the female genitalia, shape of the sternum and number of teeth in the cheliceral claw. The behavioral repertory is also described for this species based on five hours of qualitative and 24 hours of quantitative observations in order to define the behavioral categories. Five behavioral categories were detected and 21 behavioral acts. The most conspicuous category was Immobility, followed by Antenniform leg movement, Environmental exploration, Self-grooming, and Feeding. It was also found that juveniles spend longer time inside the shelter, even during peaks of adult activity, which could be related to a survival strategy.


Introduction
Whip spiders (order Amblypygi) are peculiar flattened arachnids with unique spiny, robust pedipalps and extremely elongate first pair of legs (Weygoldt 2000). The group is widely distributed in the tropics , Miranda et al. (2016); but see Miranda et al. (in press)), and consists of more than 200 species with the majority of the diversity in the family Charinidae Simon, 1892. Charinidae contains three genera, Catageus Thorell, 1889 with one species, Charinus Simon, 1892 with 70 species, and Sarax Simon, 1892 with 17 species. The genus Charinus has a pantropical distribution, occurring in the Caribbean region, Central and South America, Africa, Europe, Asia and Oceania, but most of the species have been described from the Americas. However, its diversity is still not completely revealed, as shown by the many new species discovered during the last decade (Armas 2006, 2010, Armas et al. 2016, Jocqué and Giupponi 2012, Miranda et al. in press, Miranda and Giupponi 2011, Réveillion and Maquart 2015, Seiter et al. 2015, Teruel 2016, Teruel and Questel 2011, Torres-Contreras et al. 2015, Vasconcelos et al. 2016, 2014.
Like most other arachnids, whip spiders are nocturnal animals that hide in shelters during the day (such as rock crevices or inside and under logs) and venture out to forage at night (Pinto-da-Rocha et al. 2002, Weygoldt 2000. The biology of some Phrynidae and Phrynichidae species are known (e.g. reproduction, microhabitat selection/use, spatial orientation, and social behavior; reviewed in Weygoldt (2000) and Chapin and Hebets (2016)). However, little information is available for charinids, which counts with just few general behavioral studies examining reproductive biology and behavioral repertory (Gray and Robinson 1986, Pinto-da-Rocha et al. 2002, Weygoldt 2008.
Animal behavior is defined as any act performed by an animal and involves much more than movements for locomotion or displacement, it also encompass fine movements and inactivity (Del-Claro and Prezoto 2003). As a starting point to understand the biology and ecology of an animal, behavioral repertoires (or ethograms) are important tools and give information about animal's main activities, peaks of activity, interactions, and how it distributes its activities during the day (Beck 1972, Del-Claro 2004, Lehner 1996. This kind of study allows quantitative comparisons of behavioral repertoires among different species and between individuals of different sexes (Osses et al. 2008). The observations of a given animal are represented in tables of qualification (description of behavioral categories) and quantification (frequency of each behavioral category in t time) of the acts (Del-Claro 2004, Santos et al. 2003. Few studies have been published on the behavioral repertoires of arachnids, including Opiliones (Elpino-Campos et al. 2001, Osses et al. 2008, Pereira et al. 2004, Scorpiones (Mineo et al. 2003), Ricinulei , Schizomida (Oliveira and Ferreira 2014) and Thelyphonida (Punzo 2000). There are also few works on Amblypygi, including a study on Charinus asturius Pinto-da-Rocha, Machado and Weygoldt, 2002(Pinto-da-Rocha et al. 2002, and two papers on Heterophrynus sp. (Beck 1972, Beck andGörke 1974). This paper contributes to the knowledge of Charinus in the Neotropics with the description of Charinus ruschii sp. n. and its behavior repertoire. This species occurs in the Brazilian Atlantic Forest (state of Espírito Santo, Southeastern Brazil), and is the third Charinus species discovered in Santa Teresa municipality (Fig. 4). C. ruschii differs significantly from the other known species in the area (C. brasilianus Weygoldt, 1972 andC. montanus Weygoldt, 1972), as described in detail below.

Materials and methods
Individuals of Charinus ruschii were collected at Estação Biológica de Santa Lúcia (EBSL), a biological station of 440 ha located 10 km from Santa Teresa (19°57'S; 40°31'W), in Espírito Santo state, southeastern Brazil (Mendes and Padovan (2000); Fig. 4). The EBSL is inside a remnant of Atlantic rainforest, in a geomorphologic crystalline complex with high rocky outcrops ranging in altitudes from 600 to 900 m (Thomaz 1996). Mean annual precipitation for Santa Teresa region is 1345 mm with a peak in November and a dry season in June and July (Mendes and Padovan 2000).
For nomenclature and measurements, the methods of Quintero (1981) are generally followed. The terminology of pedipalp and leg segments follows Harvey and West (1998). The article called tarsus by Harvey and West (1998) is divided here into tarsus and claw, as there is no fusion of these two segments in Charinidae. The spines of the pedipalpal patella and teeth of the chelicerae are counted from the apex to the base. Measurements of the entire type series were taken, and the measuring of the pedipalp articles was taken between the condyles of each segment in order to establish fixed points and comparable length. Total body length is usually used as diagnostic of Charinus species, but was not included here due to the contractile nature of the abdomen. Instead, the carapace width, pedipalp femur length, and femur I length seems to have more reliable diagnostic characters and are here used.
Photographs were made using a BK plus Imaging System from Visionary Digital (Palmyra, PA, USA; http://www.visionarydigital.com/) equipped with a Canon 7D digital camera at the Zoological Museum, University of Copenhagen (ZMUC). Stacks of images from multiple focal planes were combined using Zerene Stacker (Zerene Systems LLC, http://zerenesystems.com/cms/stacker) and processed in Photoshop CS6 (Adobe, San Jose, CA, USA) to adjust color, brightness, and contrast, and remove blemishes. The plates were mounted in Corel Draw X5 (Corel, Mountain View, CA). One female was examined with scanning electron microscopy (SEM). The SEM work was carried out with a JEOL JSM-6390LV at the Center for Scanning Electron Microscopy of the Museu Nacional/UFRJ.
The distribution map was produced and edited using ArcGis 10.2 (ESRI 2014) with vector layers for countries and states, and a raster background layer for the vegetal cover and urban occupation (made available by the Brazilian Ministry of the Environment, http://mapas.mma.gov.br/mapas/aplic/probio/datadownload.htm). The coordinates were obtained with Google Earth given the localities in the labels and information in the literature.
The behavioral repertory of Charinus ruschii was recorded in the Laboratory of Arachnology at the Escola Superior São Francisco de Assis/ESFA, Brazil. Between June and July 2004, 17 specimens of Charinus ruschii (12 adult females and 5 juveniles) were collected inside caves and rock crevices at the study area. The individuals were kept separately from each other in captivity in plastic boxes (15 cm long X 11 cm wide X 7 cm high), which contained one rock (that was used by them as a shelter), mud as substrate, and a piece of wet cotton to maintain humidity. Each plastic box received a number that was used in the randomization process (see below). The laboratory room was kept under darkness as this species lives in caves and rock crevices, and red light was used during observations to avoid disturbing the individuals. The whip spiders were fed with fruit flies (Drosophila sp.), moth flies (Psychoda sp.), and unidentified species of butterflies and moths every three days (one prey per day of feeding). Five hours of observations allowed the definition of five categories and 21 different behavioral acts (Table 1). The individuals were kept seven days under captivity before the behavioral observations.
Twenty-four hours of quantitative observations were made for 24 days, in which 60 observations of 1 minute was performed each day. The hour of the day to be studied was randomly chosen (24 pre-defined days) and thus was spread throughout the whole study. That is, in day 1 we could perform the study from 10 am to 11 am, whereas in day 2 from 7 pm to 8 pm, and so on. The specimens were numbered from 1 to 17 and the order to be observed was randomly defined before the behavioral study (following Pinto-da-Rocha et al. (2002);Machado, G. (pers. comm, 6 April 2004)). In total, 1440 minutes of observation were recorded totaling 24 hours and covering day and night. During the day, and after feeding, whip spider specimens remained resting. Voucher material is deposited in the Arachnology section of the Museu Nacional do Rio de Janeiro, Universidade Federal do Rio de Janeiro (MNRJ). The voucher numbers are in the list of type material.

Categories/behavioral acts Frequency (%) Immobility: stand still in an environment
48.89 Stand still with abdomen leaning over the ground: specimen stays totally still outside the shelter with the body leaning on the ground 6.81 Stand still with abdomen distant from the ground: specimen stays totally still outside of the shelter with abdomen distant from the ground 20.00 Inside the shelter: specimen stays still inside the shelter with the body leaning over the ground 22.08 Antenniform leg movement: stand still with the antenniform legs in movement 41.60 Stand still with abdomen leaning over the ground and moving antenniform legs backward: specimen stays still and smoothly moving antenniform legs backward 2.92 Stand still with abdomen distant from the ground and antenniform legs waving under the body: specimen stays still with alternate movements of the antenniform legs backward and forward

31.25
Stand still with antenniform legs touching the ground: specimen stays still and touching the ground with antenniform legs 1.53 Stand still with antenniform legs erect: keep the body distant from the ground and smooth movements of the antenniform legs over the body 1.94 Stand still with antenniform legs pointing forward: antenniform legs in a forward position making smooth movements 3.96 Environmental exploration 6.11 Laterally walking: walking to the sides inside the plastic box, like a crab 1.18 Walking with the antenniform leg erect and pointed forward: slowly walking without moving the antenniform legs and in a forward position 2.36 Walking with antenniform legs erect and pointed backward: slowly walking without moving the antenniform legs and in a backward position 0.14 Walking and touching the ground with antenniform legs: slowly walking touching and feeling the ground with antenniform legs 0.56 Walking with antenniform legs pointed forward and second pair of legs touching the ground: slowly walking throughout the box with antenniform legs in a forward position and second pair of legs touching the ground 0.55 Walking with first and second pair of legs touching the ground: slowly walking all over the box touching its walls with antenniform legs and the ground with second pair of legs 1.04 Walking with antenniform legs in a lateral position and second pair of legs touching the ground: walking with antenniform legs in a perpendicular position in respect to body axis and second pair of legs touching the ground 0.28 Feeding 0.76 Eating a prey: to lacerate the prey with the chelicerae, with abdomen distant from the ground. 0.76 Self-grooming 2.64 Cleaning the pedipalps: rub the pedipalps all over the chelicerae 1.18 Cleaning first pair of legs: rub the antenniform legs over the pedipalps and/or the chelicerae 0.69 Cleaning second pair of legs: rub the second pair of legs over the pedipalps and/or the chelicerae 0.35 Cleaning third pair of legs: rub the third pair of legs over the chelicerae 0.07 Cleaning fourth pair of legs: rub the fourth pair of legs over the chelicerae 0.35

Taxonomy
Family CHARINIDAE Quintero, 1986 Genus Charinus Simon, 1892 Charinus ruschii sp. n. http://zoobank.org/1AAB23A6-5DD9-4580-A97B-956F2BF0E000 Figures 1, 2, 3, 4 Diagnosis. Charinus ruschii can be easily recognized by the sucker-like female gonopod, presence of three spines on the pedipalp tarsus, large size (carapace circa 80% wider than that of C. brasilianus and C. montanus), small unique platelets of the sternum, similar size of the proximal segment of tarsus I compared to the other segments, and cheliceral claw with 10 teeth. Etymology. The species is named after the late agronomist and naturalist Augusto Ruschi , who played an important role in the investigation and conservation of the Atlantic Forest, and who was born in the city of the type locality of the new species. He was also involved in the creation of Estação Biológica Santa Lúcia (Biological Station Santa Lúcia, a forested reserve) where the new species was found. In 2016 is also the centenary of his birth.
Description. Carapace (Fig. 1A): flattened, wider than long (1.4 times), slightly bent downwards below lateral eyes; thin median furrow reaching fovea starting from median eye tubercle. Anterior margin rounded, with 6 frontal setae. Frontal process large, triangular, not visible from above. Three pairs of shallow furrows on lateral side of carapace, and an oval fovea. 1st pair of furrows placed just behind the lateral boss; furrows not reaching the middle line. Median eyes and tubercle present. Lateral eyes well developed, 1 small setae behind each triad of eyes; lenses directed upwards and anteriorly. Sternum (Fig. 1B): 4-segmented, all articles well sclerotized. Tritosternum with round basis, projecting anteriorly in a small blunt tubercle, surpassing the base of the pedipalp coxae, with 2 apical, 2 median and 2 basal setae, with smaller ones spread from the middle to the base. Middle piece (tetrasternum) in one convex piece, with pair of large setae in its apex, and several small ones at its base. Third piece (pentasternum) formed by 1 convex piece, smaller than middle piece, with 2 long setae at its top and several setae at its base. Sternites separated from each other by the length of the third piece. Metasternum paired in its anterior half, with an anterior setae in the membranous region followed by 2 to 3 setae in the sclerotized area, in a longitudinal row from the non-sclerotized to the sclerotized region; distal border with a small elevation bearing 6-8 large setae. Abdomen (Fig. 1A): oblong, with almost indistinguishable punctuations. Ventral sacs not present. Chelicera ( Fig. 2A): cheliceral furrow with 4 internal (prolateral) teeth; first tooth (upper) bifid with proximal cusp much larger than distal cusp. Third tooth slightly thinner and shorter than second. Fourth tooth one third larger than the third. No tooth in the external row of the basal segment. Mesal face with several small setae. Claw with 10 denticles.
Pedipalp: Trochanter (Fig. 1G): large spiniform ventral apophysis, located in the posterior border of the trochanter, bearing 13 large setae, and with a blunt tip pointed forward; 2 subequal spines, one at about the center of the anterior row of setiferous tubercles, the other at the external border, above the apophysis, slightly curved inwards. Femur (Fig. 1F, G): 5 to 6 dorsal spines (I>II>III>IV>V>VI) with 2 prominent setiferous tubercles before first spine; 5 ventral spines (I>II>III>IV>V), with 1 small spine displaced from the main series, dorsal to spine 1; with 2 small setiferous tubercles before first spine. Patella (Fig. 1F, G): 6 dorsal spines (I>II>III>IV>V>VI); one setiferous tubercle distal to I (about one third the size of I); spine I with 3 large and several small setae in the first third; spine II with 3-4 large setae at basal third; spine III with 1 setae in its distal third. 4-5 ventral spines decreasing in size. Tibia (Fig. 1F, G): 2 dorsal spines, the basal 2/3 the size of the distal. One ventral spine at distal half, 2/3 the basal spine dorsal. Tarsus (Fig. 1D, E): 3 dorsal spines (present since early stages of development); 2 distal, subequal between each other and 1/5 the size of the article; the proximal spine small, circa of 1/3 the size of the other two, positioned close to the proximal spine and with long setae in its base. Cleaning organ about 1/2 of the article length. Claw (Fig. 1D, E): long, with an acute, curved tip.
Legs: all segments setose. Ventral corner of the prolateral face of femora II-IV projecting in a distinct spiniform process. Femur length: I>III>II>IV. Tibia I with 23 articles; distal segments with 2 small trichobothria, 1 on the dorsal and 1 on the lateral (mesal) side of the segment; 1 trichobothria in the second, third and fourth (from distal to proximal) segments, close to the distal border, all dorsally positioned; no trichobothria on other segments. Tarsus (basitarsus+distitarsus) I with 41 articles covered with large number of sensilla (Fig. 3B-F). Tip of leg I with small modified claw, emerging from common base (Fig. 3F). Lateral claws smaller than middle claw. Segments covered with at least 2 sensilla types, the bristle sensilla (br) and the club sensilla (c; Figs 3C, D). The club sensilla are found in the first 3 or 4 segments of tarsus I, whereas the bristle sensilla are present in all segments of tarsus and tibia I, decreasing in number from the tip to the base of the segments.
Genitalia. female gonopod (Fig. 3A): posterior margin of genital operculum straight, with several setae along its margin and on its surface. Gonopods sucker-like, with a broad base, a constriction in the middle of the short stalk, and a rounded opening of the atrium; stalk slightly curved inwards. Base soft and wrinkled.
Male. not known.

Behavioral repertory
The most conspicuous behavioral category was Immobility (48.89%), followed by Antenniform movement (41.60%), Environmental exploration (6.11%), Self-grooming (2.64%) and Feeding (0.76%) ( Table 1). Within the Immobility category, the most frequently performed behavioral act was Inside the shelter (22.08%), and 83.04% of the total were performed by juvenile. In the Antenniform movement category the behavioral act Stand with the abdomen distant from the ground and first pair of legs waving over the body was the most frequent (31.25%), showing the relevance of the antenniform legs and its sensory structures (Beck et al. 1977, Hebets 2002, Hebets and Chapman 2000, Igelmund 1987), which main functions are: (1) intra-specific signals, (2) navigation,  (3) olfactory sensitivity, and (4) foraging. The main act of Environmental exploration was Walking with first pair of legs erect and pointed forward (2.36%); due to sensorial function, the forward position of the first pair of legs could be related to foraging (Hebets 2002, Weygoldt 2000). Likewise, Pereira et al. (2004) found better significance in environmental exploration categories linked with the use of the second pair of legs in the harvestman Ilhaia cuspidata Roewer, 1913, that has sensorial function too. In the Self-grooming category, Cleaning the pedipalps was the most expressive act (1.32%). Whip spiders in general use their chelicerae and pedipalps for cleaning their appendages (Alexander 1962, Weygoldt 2000; in the tarsus of the pedipalps is present a structure formed by two parallel rows of modified setae that cleans the legs (i.e. cleaning organs or cleaning brush, sensu Weygoldt (2000)). Legs with higher percentage of cleaning were the antenniform legs (0.69%), probably related to their sensorial function (i.e. sensilla and trichobothria; Foelix et al. (1975) ; Fig. 3). Also, Pereira et al. (2004) observed that legs with sensorial structures were the most cleaned in I. cuspidata. Feeding represented only 0.76% of all behaviors. Specimens of Psychoda sp. were always eaten when given to the whip spiders, whereas drosophila and butterflies were found dead after three days of being offered. The motivation of C. ruschii to feed on live animals was similar to that of Damon gracilis Weygoldt, 1998(Weygoldt 2000, and different to that of Heterophrynus batesii (Butler, 1873) which accept dead animals (Beck and Görke 1974). Similarly to other whip spiders and other arachnids such as harvestmen, scorpions, spiders, and vinegaroons (e.g., Foelix (1996); Punzo (2000); Elpino-Campos et al. (2001); Pinto-da-Rocha et al. (2002); Mineo et al. (2003)), C. ruschii shows highest peaks of immobility during the day than the night, beginning its period of activity (Environmental exploration) at dusk (i.e. 18:00 hrs). The Immobility behavior was common from 08:00hrs to 14:00 hrs, and Environmental exploration was between 22:00hrs and 02:00hrs. Despite of the described patterns of immobility and foraging, some C. ruschii specimens were inactive during the night and feed themselves during the day (Fig. 5), which could be explained by the lower or non-incidence of light during the day in the caves where they live. Day activities were also observed in other cave species, such as C. asturius and two genera of harvestmen, Iporangaia Mello-Leitão, 1935and Iguapeia Mello-Leitão, 1935(Hoenen and Gnaspini 1999.

Remaining inside the shelter
In the laboratory experiment, specimens of C. ruschii remained outside the shelter during the day, as observed by Pinto-da-Rocha et al. (2002) in C. asturius. This is different to observations in situ for both C. ruschii and C. asturius.
In average, each adult (n = 12) spent 4 minutes of their total time inside the shelter (i.e. 1440 minutes), while the mean for juveniles (n = 5) was 13.2 times higher than adults (mean = 52.8 min; test w for separate variance estimates t = 7.875, P < 0.0001; Fig. 5). Field observations of juvenile C. montanus show high rates of recapture in their shelter (i.e. high site fidelity). These data suggest that juveniles probably spend more time inside the shelter and this can be considered a survival strategy, which decreases the chances of being caught during the foraging periods (Chapin and Hebets 2016); the time spent foraging is also smaller than those spent by the adults, the juveniles adopt a "sitand-wait" hunting strategy. Even in the peaks of activity (22:00 hrs and 02:00 hrs; Figs 5 and 6), most juveniles stayed inside the shelter. Salvestrini and Gasnier (2001) studied the differences in activity patterns between juveniles and adults of females and males of the spiders Ctenus amphora Mello-Leitão, 1930 andC. crulsi Mello-Leitão, 1930, and confirmed that juvenile spiders were significantly more sedentary than adults from both sexes in C. amphora and male adults from C. crulsi. They suggested that sedentary behavior could be related to a foraging strategy, diet and resource available. Even more, Kreiter and Wise (1996), Schmitt et al. (1990) and Sullivan and Morse (2004) argued that, in general, adult spiders show more activity than juveniles, and that the difference between males and females is related to a sexual behavior in searching for males.
Charinus ruschii is a rather large species (see Table 2), but not as large as C. mysticus and C. jibaossu, the two largest species of the group. Charinus mysticus and the new species also have three spines on the pedipalp tarsus, trichobothria bc closer to sbf than to bf, and short stalk of the female gonopod. However, C. mysticus can be easily distinguished from the new species by the development of the median eyes and tubercle (reduced in C. mysticus and well-developed in C. ruschii), the shape of the frontal process apex (rhombus in the old species and acute in the new), and the number of teeth on the chelicerae claw (4 in C. mysticus and 10 in C. ruschii).
Charinus jibaossu is quite similar to the new species, despite its larger size, but differences occur in the number of ventral spines on the pedipalpal patella (3 in C. jibaossu and 5 in C. ruschii), the size of the stalk of the female gonopod (long in C. jibaossu and short in C. ruschii) and the presence/absence of a constriction close to the apical border of the female gonopod (absent in C. jibaossu and present in C. ruschii).
All specimens of C. ruschii have three spines on the pedipalp tarsus, whereas C. jibaossu is polymorphic, with one to three spines in this segment of the pedipalp ).
Charinus potiguar is also similar to C. ruschii, but the frontal process is shorter, the dorsal pedipalp femur has 3 spines (in contrast to 5), the dorsal patella has 5 spines (in opposition to 6), the ventral patella has 2 spines (while the new species has 5), the pedipalp tarsus has 2 spines (C. ruschii has 3), the female has long stalked gonopod with divergent "V" shaped openings, and the proximal tooth of the basal segment of the chelicerae lacks the distal expansion.
The presence of well-developed median eyes and tubercle distinguish C. ruschii from C. eleonorae (which has reduced median eyes and tubercle) and from C. troglobious (which is completely blind). Charinus eleonorae also has a uniquely high number of setae on the frontal border of the carapace (ten) while all other species of the group have at most six. Charinus troglobius has a distinctively short tritosternum, which does not extend between the pedipalp coxae, a morphology that is quite different from almost all other species of the genus.
The pedipalp spine number is the distinguishing character between C. ruschii and C. bromeliaea. This species has three dorsal and three ventral spines on the femur, and four dorsal and two ventral patella spines. On the other hand, the femur of C. ruschii has five dorsal and five ventral, and the patella has six dorsal and five ventral spines. Moreover, C. bromeliaea has two dorsal spines on the pedipalpal tarsus, while C. ruschii has three. Similarly, C. asturius and C. acaraje have fewer spines on the pedipalp compared to C. ruschii. Charinus acaraje also possesses an extremely reduced frontal process, a character present only in this species. Charinus montanus and C. brasilianus live in sympatry with C. ruschii (Fig. 4), but these species have striking differing characters. Charinus montanus is a unusual species due to the presence of clavate setae over most of the body (prosoma, legs and pedipalps), an acute projection in the frontal carapace border (anterior to the median eyes), tarsus I with 28 segments, extremely long first tarsus I segment, flattened and wide sternum platelets, and dark brown body color (even in old museum specimens). Charinus brasilianus, on the other hand, has the usual Charinus shape, but is also dark brown colored, and the female gonopod has a unique invagination on the frontal side. Moreover, C. montanus and C. brasilianus have seven teeth in the cheliceral claw, while C. ruschii has ten, and the two older species are considerably smaller than the new one (with the exception of the long pedipalps of the sexually dimorphic males of C. brasilianus; Table 2).
Regarding the other South American species of Charinus, the new species differs from C. insularis, C. koepckei and C. vulgaris by the absence of claws in the female genitalia, a feature present in the latter three species. Charinus ruschii is also different from C. insularis in the number of ventral spines on the femur (five in the new species and 3-4 in C. insularis), the number of articles in the tarsus I (41 in C. ruschii and 43 in C. insularis) and number of teeth in the cheliceral claw (ten in C. ruschii and 6-8 in C. insularis). Charinus koepckei differs from C. ruschii in the presence of the tetra and pentasternum formed by two separate small rounded concave platelets, trichobothria bc midway between bf and sbf, and the cheliceral claw with seven teeth. The Amazonian C. vulgaris has fewer spines on the pedipalp (e.g. 2-3 dorsal and three ventral on the femur), lacks the median eyes and tubercle, and has only four teeth on the cheliceral claw.
Charinus ruschii has similar appearance to C. gertschi Goodnight & Goodnight, 1946, but can be differentiated by the number of spines on dorsal patella (six in the former and five in the latter) and the shape of the sternum (small convex sclerotized platelets, in contrast to broad flatten platelets, respectively).
The other Charinus of the world can be distinguished by the shape of the female genitalia. The australianus species group has cushion-like gonopods, the bengalensis species group have finger-like gonopods and the seychellarum species do not have a gonopod. This is one of the first detailed descriptions of leg I of a species of Charinidae. The number and amount of sensory structures is considerably different from that described for Phrynidae (Foelix et al. 1975, Igelmund 1987), but it is rather similar to that of C. ioanniticus (Kritscher, 1959), a distant related species (Miranda et al. in press). Charinus ruschii has fewer types of hairs and sensory openings than Heterophrynus elaphus Pocock, 1903, which has at least five different sensory structures (bristle sensilla, porous sensilla, club sensilla, rod sensilla, and the pit organ; Igelmund (1987)). Charinus ruschii has only two different sense organs: bristle sensilla and club sensilla (Fig. 3B-F). Another difference is the relative size of the claws at the end of tarsus I. Charinus ruschii has the lateral claws smaller than the median claw, while species of Heterophrynus have the opposite size relation (Foelix et al. (1975) ; Fig. 3E). The claws lack a subterminal opening, suggesting that in Charinus species the claws probably lack a sensory function, different to what is found in Phrynidae (Igelmund 1987).

Behavior
The observations presented here enforce the "sit-and-wait" hunting strategy pattern within whip spiders (e.g. Alexander (1962), Gray and Robinson (1986), Pinto-da-Rocha et al. (2002), Weygoldt (2000)) and other arachnids (Mineo et al. 2003, Punzo 2000, with a frequent representation of immobility in their activity patterns. More accurate studies are necessary to a complete understanding of survival tactics in Amblypygi, where comparisons between feeding strategies as well as activity rhythm in juveniles and adult males and females should be accessed. Charinus ruschii is currently known only from the type locality, Estação Biológica Santa Lúcia, and dwells in specific microhabitats, which might make them an endangered or vulnerable species in account to indiscriminate anthropic deforestation of the Atlantic Forest. The threat to this environment is of high concern due to the high levels of endemism (Myers et al. 2000).