CHTHONIUS (CHTHONIUS) ONAEI N. SP. (CHTHONIIDAE, PSEUDOSCORPIONES), A NEW EPIGEAN SPECIES FROM CROATIA

A new epigean pseudoscorpion, Chthonius (Chthonius) onaei n. sp. is erected from Podašpilje, nr. Omiš, Mt. Omiška Dinara, Dalmatia, Croatia. Its interrelations with two close congeners, Chthonius (C.) litoralis Hadži, 1933 and Chthonius (C.) dalmatinus Hadži, 1930 are briefly discussed.


INTRODUCTION
The investigation of the pseudoscorpion fauna in Croatia has a long history; the first data on pseudoscorpion species from Croatia date back to the first half of the XIX century (Ozimec, 2004) but is characterized by an uneven intensity which depended on the sporadic interest of various foreign arachnologists and the available pseudoscorpion material for study.The papers of Tömösvary and Daday contributed to a better knowledge of this group in Croatia (Daday 1888(Daday , 1889;;Tömösvary 1884).Studies carried out by Beier and Hadži in the first half of the XX century, shed new light on the biodiversity of this arachnid group in Croatia (Dalmatia) (Beier 1928(Beier , 1929(Beier , 1939;;Hadži 1930Hadži , 1932Hadži , 1933)).In the past twenty five years investigations carried out by Ćurčić have resulted in the establishment of a significant number of new pseudoscorpion taxa (genera, subgenera and species), both epigean and cavedwelling forms (Ćurčić, 1974, 1984, 1987, 1988;Ćurčić et al. 2004;Dimitrijević and Radja 2008).Thus, the number of known pseudoscorpions from Croatia has risen to 109 species.
The most numerous pseudoscorpion family in Croatia is the Neobisiidae with 84 known species and subspecies.The genus Chthonius C. L. Koch, 1843 and its three subgenera are represented with 27 species and subspecies in Croatia (Ćurčić, 1974;Harvey, 1990).The vast majority of known species pertaining to this genus are cavernicolous, populating different structures of the welldeveloped karst relief in Croatia (caves, pot-holes, sink-holes).Bearing in mind the estimated number of caves in Croatia (7000-8000, Tvrtković and Veen, 2006), the number of known cave-dwelling pseudoscorpions is far from definitive.Further biospeological investigations will, without doubt, reveal many more pseudoscorpion taxa new to science.Tergites uniseriate and smooth.Tergal formula: 4-4-4-4-6-6-6-6-6-6.Male genital area : Sternite II with ten setae.Sternite III with eleven and ten setae on each side of the median V shaped groove, whilst eleven setae are present on the posterior sternal border.Two or three small setae along each stigma.Sternite IV with eight setae and one to two microsetae along each stigma.Sternites V-X with 9-6-6-6-6-7 setae, respectively.

A careful examination of a small sample of pseudoscorpions collected by
Galea inconspicuous (Fig. 3).Cheliceral palm with 6 setae and 2 small additional microsetae (Fig. 3).Movable cheliceral finger carries one seta.Seven and five teeth of uneven size are carried on the fixed cheliceral finger.Flagellum of 11 blades.
Manducatory process with two long acumminate setae.Tiny granulations developed on both exterior and interior side of the chelal palm and femur.Other pedipalpal articles smooth and elongated (Figs. 1 and 2).Fixed and movable chelal fingers straight, with 37 and 32 close-set teeth respectively.Chelal finger longer than chelal palm (Tab.1).Pedipalpal femur considerably longer than carapace and also longer than chelal finger (Tab.1).
Coxa I bears 6, coxa II 4, coxa III 5 and coxa IV 6 setae.Nine or eight spines are carried on coxa II and 7 or 6 spines on coxa III.Coxal spines are finely pinnate on both sides.Intercoxal tubercle with two setae (Fig. 5).
Leg IV: tibia, metatarsus and telotarsus carry a single sensitive seta each (Fig. 4).Linear measurements (in mm) and morphometric ratios are presented in Table 1.
Pedipalpal articles elongated and smooth.Some tiny granulations are developed on the interior and exterior side of the pedipalpal femur (Fig. 10).Chelal finger 1.48 times longer than chelal palm.Pedipalpal femur considerably longer than carapace (Tab.1).Trichobothrial disposition as illustrated in Figs. 1  and 9.   Coxa I bears 4 and 5 setae; coxa II 4 setae; coxa III 4 and 5 setae and coxa IV 6 setae.Six and four finely pinnated coxal spines are carries on coxae II and III.Intercoxal tubercle with two small setae.
Leg IV: tibia, metatarsus and telotarsus carry a single sensitive seta each (Fig. 14).Linear measurements (in mm) and morphometric ratios are presented in Table 1.The morphometric ratios of numerous body parts display significant differences between the males of these two species, such as: femur length to breadth ratio (5.235 in C. litoralis vs. 4.75 (3.42 in C. litoralis vs. 3.91 in C. onaei).
The onaei females also differ from females of C. (C.) dalmatinus, from Pišurka pećina Cave, Korčula village, island of Korčula, Dalmatia, in many aspects: in the male sex, the female of C. onaei is characterized by overall smaller body dimensions when compared to the corresponding characters of the female of C. dalmatinus (Table 1).
Further differences between the females of these two species comprise: carapacal setation ( 22 For differences in morphometric ratios of leg IV articles see Table 1.

REMARKS
The finding of a new epigean pseudoscorpion species Chthonius onaei n. sp. on Mt.Dinara in Dalmatia which is part of the well-developed Dinaric Karst, supports the view that this region is rich in endemic and relict representatives of this arachnid group.Bearing in mind the fact the estimated number of caves in Croatia (7000-8000, Tvrtković and Veen, 2006), and that there are no continuous intensive investigations of epigean pseudoscorpion fauna in Croatia, the number of known epigean and cave-dwelling pseudoscorpion species is far from a definitive one.Further investigations will, without doubt, reveal the presence of many more pseudoscorpion taxa new to science.