A new species of Sickesia ( Laniatores : Stygnidae : Opiliones ) and new records for the State of Piauí , Brazil

Sickesia tremembe sp. nov. is described from Piaui, Northeast Brazil (type-locality: Sete Cidades National Park, Brasileira and Piracuruca municipalities). It differs from S. usta and S. helmuti by the clavate male femur IV and chelicerae segment I with a pair of large tubercles on retrolateral surface. The Stygnidae Stygnus polyacanthus (Mello-Leitao, 1923); the Cosmetidae, Gryne pluriarcuata Mello-Leitao, 1936 and undetermined species of Paecilaema and Gryne and also repre- sentatives of Escadabiidae and Sclerosomatidae (Gagrellinae) are recorded from this state, for the first time.

Etymology.The specific name makes reference to the extinct indigenous tribe Tremembé, which lived in the State of Piauí and was known by its swimming abilities and courage of the warriors.
Diagnosis.Males of Sickesia tremembe resemble those of S. helmuti by the larger spines on areas I and II, but differs by the smooth claws on tarsi III-IV.S. tremembe differs from S. usta and S. helmuti by the clavate male femur IV and chelicerae segment I with a pair of large tubercles on retrolateral surface.
Description.Holotype male (MPEG 0042).Measurements.Dorsal scutum: length 1.46, width 1.48; prosoma: length 0.65, width 1.20; interocular distance 1.05; chelicerae: II 0.57; III 0.35; pedipalpus 1.91; legs: I 5.70; II 9.90; III 7.40; IV 11.50.Dorsum.Anterior margin with two to three small tubercules on each side.Prosoma small tuberculate, with one forward spine near anterior margin.Lateral margins with tubercles from coxa II to posterior margin.Area I with five to six tubercles each side (one larger close to median groove); II with 10 tubercles (two larger); III with 11 tubercles (two larger on center of area).Posterior margin with one central with one larger each side and seven to three lateral tubercles.Free tergite I with two central tubercles, one larger each side and four lateral; II with one central with one larger each side and four lateral tubercles; III with two small central one larger each side and three lateral tubercles.Anal plate with one anterior and one posterior row of tubercles.Venter.Coxa I with six anterior tubercles, five median and four posterior; II with eight anterior tubercles, six median and for posterior; III with seven anterior tubercles, four median and six poste- Biological note.All specimens were collected in tropical semi-deciduous forests and were not found in others phytophysiognomies of the region.This formation is a dense and forested area, with canopy of 9 m, which has a few individuals with 20 m height, abundant leaf litter on the ground, high abundance of lianas on sub-canopy, absence of epiphytes; and a flatland soil, usually with emerging rocks (OLIVEIRA et al. 2007).

Notes on the harvestman fauna from Piauí
The inventory of arachnids over Piauí was carried out at three main sites: Sete Cidades National Park (between 2006and 2007), Nazareth Farm (between 2003and 2005) and Bonito Farm (between 2006and 2007).The Sete Cidades National Park (04º06'25.76"S,041º40'39.32"W)comprises well-preserved 6221 ha and it is covered by six phytophysiognomical types of Cerrado (savanna-like vegetation): grassland (medium tall grassland consisting mainly of bunch grasses occasionally/seasonally flooded); cerrado sensu strictu (evergreen broad-leaved sclerophyllous shrubland); cerrado rupestre (deciduous subdesert shrubland with succulents); cerradão (evergreen broad-leaved woodland); gallery  The collecting methods and sampling intensity was not standardized over these localities; which hampered application of statistical comparisons between the data obtained.We sampled using six main techniques: beating tray (one hour samples); nocturnal hand searches (one hour samples); sweeping net (one hour samples); pit-fall traps for invertebrates (500 ml plastic buckets, sunk into the ground flush with the surface, filled with 300 ml of 70-80% ethyl alcohol; five days samples); pit-fall traps with drift fences (blocks of four 60 l plastic buckets, arranged like a "Y", with drift fences of 60 cm high; 24 h samples); and Winkler apparatus (1 m 2 litter samples).
We examined 354 harvestmen (341 that we collected and 13 that were deposited in scientific collections) from different localities over the State, belonging to nine species and four families: Stygnidae, Stygnus polyacanthus (Mello-Leitão, 1923) (17 specimens), and Sickesia tremembe sp.nov.(11 specimens); Cosmetidae, Gryne pluriarcuata Mello-Leitão, 1936 (89 specimens), an undetermined species of Gryne Simon, 1879 (one specimen), and three undetermined species of Paecilaema C.L. Koch, 1839 (see table I for abundances); an undescribed species of Escadabiidae (possibly belonging to the genus Baculigerus H. Soares, 1979) (nine specimens); and also a single immature and undetermined specimen of Sclerosomatidae (Gagrellinae).These are the first records of those families from the State of Piauí.S. polyacanthus is widely distributed over the Northeast  ROCHA 1997) and it was usually collected on the underside of fallen trunks or trunks on decomposition, including palm tree trunks.This species was collected at Sete Cidades National Park, Nazareth Farm and Sítio Ouro Verde (see Tab. I).
Gryne pluriarcuata was the most abundant species sampled and exhibits a gregarious behavior and can be found on leaf litter.This species was known only for its type locality (Tapera, Pernambuco), according to KURY (2003); and now has its geographical distribution extended to Sete Cidades National Park, Nazareth Farm and surroundings of Teresina.The single specimen of Gryne sp. 1 was collected at the Mocambinho Ambiental Park (Teresina), on a pit-fall trap sample, with one specimen of G. pluriarcuata.The specimens of Paecilaema sp. 1 were collected at Sete Cidades National Park, Nazareth Farm, Bonito Farm and in the surroundings of the cities of Teresina and Oeiras (southern Piauí).The others species of Paecilaema were sampled exclusively at Uruçuí-Una Ecological Station (Paecilaema sp. 2), that is a huge protected area of 204,315 ha, on southern Piauí, in the domains of the Cerrado Biome; or at Uruçuí town (Paecilaema sp.3).The representatives of this genus were seen wandering on the forest floor, above termite nests and tree trunks.The specimens of Escadabiidae were usually collected with pitfall traps, and a few specimens were captured, by nocturnal hand searches, inside termite nests at the Sete Cidades National Park and Bonito Farm.Sclerosomatidae was recorded only by a single specimen from the town of Uruçuí and it was collected using a pit-fall trap with drift fences in an exploratory expedition.
Although we have shown an abundance pattern of high dominance of two species (G.pluriarcuata and Paecilaema sp. 1) and low species richness (nine species), this fact can not be considered as the real diversity pattern of the harvestman fauna of Piauí, because the sampled areas are inexpressive compared to the hole State´s dimensions and some regions remains unsampled, including those covered by the Caatinga Biome or the humid forested enclaves present on southern region.A few authors (BRAGAGNOLO & PINTO-DA-ROCHA 2003, PINTO-DA-ROCHA et al. 2005, PINTO-DA-ROCHA & BONALDO 2006) showed that the harvestman richness in Cerrado is the lowest (4-7 species per site), when compared to forest biomes such as the Atlantic forest (12-64 species per site) or Amazon forest (21-28 species per site), which creates an expectative of some new findings with an increase of the harvestman sampling at Piauí State.Besides, the low richness of harvestmen species from Piauí appears to be restricted to the rare environmental humid conditions.Therefore, an intensive collecting effort at the remaining unsampled regions is highly required for a robust knowledge of this fauna.