Charinus taboa, Vasconcelos, Ana Caroline Oliveira, Giupponi, Alessandro Ponce de Leao & Ferreira, Rodrigo Lopes, 2016

Vasconcelos, Ana Caroline Oliveira, Giupponi, Alessandro Ponce de Leao & Ferreira, Rodrigo Lopes, 2016, Description of a new troglomorphic species of Charinus Simon, 1892 from Brazil (Arachnida, Amblypygi, Charinidae), ZooKeys 600, pp. 35-52 : 37-44

Taxon classification Animalia Amblypygi Charinidae

Charinus taboa sp. n. Figs 1-3, 4-8, 9-13, 14-17, 18-19, 20-23

Type-locality.

BRAZIL, Minas Gerais: Sete Lagoas, 19°28'29.68"S, 44°19'41.31"W, Taboa Cave and BR 24 cave (19°27'59.89"S 44°19'48.47"W)

Type-material.

Holotype male (MNRJ 09091) from Taboa cave (19°28'29.68"S, 44°19'41.31"W), Sete Lagoas, Minas Gerais, Brazil, 15 Sept. 2005, R. L. Ferreira leg. Paratypes: juvenile female (MNRJ 09092), juvenile female (MNRJ 09092), female (ISLA 4019), female (ISLA 4020), female (ISLA 4021), male (ISLA 4022), male (ISLA 4023), juvenile male (ISLA 4024), juvenile male (ISLA 4030) with the same data as holotype, female and male (CAVAISC-ARAC 0007) from BR 24 cave (19°27'59.89"S, 44°19'48.47"W), Sete Lagoas, Minas Gerais Brazil, 22 Jun. 2015, F. Bondezan leg. and female (CAVAISC-ARAC 0008) from BR 24 cave, Sete Lagoas, Minas Gerais Brazil, 18 Dec. 2015, F. Bondezan leg.

Diagnosis.

Charinus taboa differs from other species of the genus by the following combination of characteristics: frontal process with thickened apex; median eyes reduced, with flattened tubercle; lateral eyes not developed and without pigmentation (little pigmentation in smaller individuals); tritosternum with a slightly forked apex; pedipalps sexually dimorphic; femur of the pedipalp with 4-5 dorsal spines (typically 5) and 5-6 ventral spines (typically 5); patella of the pedipalp with 6-7 dorsal spines (typically 6) and 4 ventral spines; distitibia of the leg IV with 16 trichobothria; female gonopod sucker-like, with irregular opening and edges with a small fold; male gonopod with pairs of Pi and LoL1 emerging from each side of the Fi with thin prolongations, and pairs of LoD and LoL2 claw-shaped emerging from the interior of the upper portion of Fi.

Description.

Carapace (Figs 1-3, 9): Flattened. Wider than long (ratio length/width a little less than 3/4). Anterior margin rounded with corners flattened downwards. Six strong setae on the anterior margin projected upwards (one extra seta is found centrally in a female), the central two setae usually located directly in front of the tubercle of the median eyes. Frontal process triangular in shape, with thickened apex and visible in dorsal view. Carina begins at the corners of the anterior margin and extends from the coxae of leg II to the corners of the posterior margin. Median eyes reduced, with flat tubercle. Lateral eyes not very developed, without pigmentation (less pigmentation in smaller specimens) and with one seta posterior to each triad. Frontal hump present at each side, starting just at the front of the lateral eyes and ending in a depression located at each side of the carapace. Fovea located posterior to the center, from which radiate two pairs of furrows in anterior and posterior orientation like an “X”. Median depression located on each side between these two pairs of furrows. A thin furrow follows medially from the median eye tubercle and reaches the posterior margin. Punctuations arranged in lines and spots, more densely in the anterior region.

Sternum (Figs 8, 11): Tri-segmented with all segments sclerotized and convex. Tritosternum projected anteriorly, elongated, cone-shaped, with slightly forked apex, with one apical pair of strong setae and three median strong setae in the holotype, and one apical, one medial and one basal pair of strong setae in the paratypes. Few setae along the tritoesternum. Second segment (mesosternum) rounded, with one strong seta at each upper corner and few setulae encircling the base. Third segment (metasternum) rounded, with one strong seta at each upper corner and few setulae encircling the base. The segments are separated from each other approximately by the diameter of the mesosternum.

Abdomen (Fig. 1): Oblong, with punctuations barely distinguishable.

Chelicera (Fig. 10): Cheliceral furrow with 4 inner teeth. The distal tooth is bifid, the distal cusp being larger than the proximal. Teeth length: IV>Ia>Ib=II>III. Claw with 8-9 denticles. Dorsal setae located distally and in the inner side of the chelicerae.

Pedipalp (Figs 4-7, 12, 13): Trochanter: ventral spiniform apophysis pointed forwards with a series of subequal setiferous tubercles; two spines of subequal length located aligned on the prolateral face, the first being near the medial region and the second dorsally to the projection of the apophysis and close to the femur; three setae aligned between the spines and two located basally to the first spine; dorsal oblique series of strong setae. Femur: dorsal portion with three strong setiferous tubercles on the basal region, one being located more ventrally; several strong setae along the segment; four-five dorsal spines (typically five) decreasing in size: F1>F2>F3>F4>F5; five-six ventral spines (typically five) of sizes: FI>FII>FIII>AI>FIV>FV; some secondary spines are present in males between the spines on the dorsal and ventral sides. Patella: some strong dorsal setae between the spines; six-seven dorsal spines (typically six) of sizes: 1>2>3>4>A1>5>6; large ventral setiferous tubercles located distally: four ventral spines of sizes: I>II>III>IV; some secondary spines between the ventral spines in males. Tibia: strong dorsal setae; two dorsal spines, the second being approximately two times larger than the first; strong ventral setae on the basal portion; one ventral spine located on the distal half of size slightly smaller than the dorsal spine one. Tarsus: strong dorsal setae and some long ventral setae; two dorsal spines on the cleaning organ, the second being approximately two times larger than the first spine. Cleaning organ occupies about half the length of the article. Claw (apotele): long with sharp curved tip.

Legs: all densely setose. Femur lengths: I>III>II>IV. Leg I: tibia with 23 articles and tarsus with 41 articles. Leg IV: basitibia with four pseudo-articles and one trichobothrium located basally on the last article. Distitibia (Fig. 17) with three basal and 13 distal trichobothria; frontal and caudal series with five trichobothria each. Basitibia-distitibia length: BTI>DT>BT4>BT3>BT2. Ratio tarsus/metatarsus approximately 3/4. Tarsus tetramerous.

Color in live specimens (Figs 18, 19): body light brown. In alcohol (Fig. 1): body yellowish; some specimens exhibit slightly reddish coloration on the carapace, pedipalps, chelicerae and legs.

Male genitalia (Figs 15, 16): GO rounded with few scattered setae. Genitalia a little wider than long. Longitudinal split occupies about half of the genital organ. Fi exceeds the genital operculum margin. Sclerotized band surrounds each side of the Fi, reaching the Pi and LoL1. Pair of Pi and LoL1 emerges in thin prolongations from each side of the Fi. Pair of LoD and LoL2 claw-shaped emerges from the interior of the upper portion of Fi, with LoL2 being ventral to the LoD. Pair of LaM claw-shaped and smaller, located ventrally to the Fi.

Female genitalia (Fig. 14): Rounded genital operculum margin with many strong setae. Gonopods sucker-like, barrel shaped and slightly wider than long. Irregular gonopods opening, with edges with a small fold retracted in a portion between the gonopods and the operculum margin, and with a bottleneck below the edges. Gonopods separated from each other by a distance smaller than the diameter of each one and from the margin of the operculum by a distance larger than its length.

Etymology.

The specific epithet is treated as a noun in apposition and refers to the name of the cave (Taboa) where most of the specimens were collected.

Distribution.

The new species is known from the Taboa and BR 24 caves, state of Minas Gerais, Brazil.

Ecology.

Amblypygids perform their vital activities, such as mating and feeding, in nocturnal periods. The most important sensory organ used by whip spiders for capturing prey is the antenniform leg, while the eyes are most important for avoiding light ( Weygoldt 2000, Pinto-da-Rocha et al. 2002). This way, amblypygids can be considered pre-adapted to subterranean life, since they are able of searching for food in a completely darkness.

Eyes in Amblypygi are also important for adjusting to circadian rhythms ( Weygoldt 2000). After many generations living in a subterranean habitat, some hypogean animals might have their activity period modified, as shown for some species of fish (Menna-Barreto and Trajano, 2015). This possible change in behavior may have occurred in Charinus taboa , as one specimen was observed preying on a Noctuidae ( Lepidoptera ) during the day (Fig. 19). Nevertheless, we cannot discard the possible scenario where the common ancestral of the clade where Charinus taboa belongs was a species that have diurnal activity of alimentation.

Contrarily to that observed, moths were considered by Weygoldt (2000) as typical preys of Heterophrynus Pocock, 1894, which are agile "sit and wait" predators, as opposed to animals of small body size, as Charinus , which behave as active predators. In ground habitats, amblypygids also act as one of the largest predators in these environments, as the fauna of underground cavities consists mostly of small arthropods ( Culver and Pipan 2009). Other invertebrates, as crickets and cockroaches, have been cited as potential preys of Charinus in caves ( Vasconcelos et al. 2013, Vasconcelos and Ferreira 2016).

Specimens of Charinus taboa were only found in two caves (Taboa cave and BR 24 cave), both located in the Bambui speleological group and near the city of Sete Lagoas (Fig. 20), in a zone with pronounced anthropization (Fig. 21). The external native vegetation was quite modified, with fragments of vegetation associated only with rocky outcrops, which comprises inappropriate areas for agriculture. Nevertheless, many outcrops were altered anthropically or completely destroyed by mining activities. Tens of caves were target of biospeleological inventories in the region where Taboa and BR 24 caves are located (R. Ferreira, data not published). Nonetheless, individuals of Charinus taboa were not found in other localities than the cited caves. Such caves are quite close to each other, with the distance between them less than 500 meters (both caves are associated to a continuous limestone outcrop) (Fig. 20). It is important to point that although both caves (Taboa and BR-24) are not connected by macro-spaces, it is plausible to assume the existence of meso-caverns in between them. Such small spaces would certainly allow the movements of individuals through the underground between those caves.

The BR-24 cave is a small cave (33,8 meters long), with a single entrance and an isolated chamber in its deepest portion, where the specimens were found. This chamber is quite moist, even during the dry season. In total, 6 specimens were found in the dry season and only one specimen was observed in the rainy season. Specimens of Charinus taboa were observed in the cave walls and ceiling, always in the deepest portion of the cave. Potential preys include moths and crickets.

During the visit to the Taboa cave (which has around 800 meters long), about 15 adults and 10 juveniles were observed. The adults were mainly found between speleothems on walls and ceiling of the cave, while juveniles were seem frequently under rocks. This behavior of sheltering among speleothems and under rocks may eventually means a response to pressure of cannibalism or predation, since others predators of bigger size (as spiders of the genus Isoctenus Bertkau, 1880) cohabit the cave. This type of behavior was also registered in Charinus potiguar and in juveniles of Heterophrynus cheiracanthus (Gervais, 1844) in the night ( Ladle and Velander 2003). All individuals of Charinus taboa were found in the inner portion of the cave, near to a large watercourse (Figs 22, 23). Similar preference was also observed in Charinus troglobius and Charinus eleonorae ( Baptista and Giupponi 2002, 2003).