RONCUS IVANSTICAE (NEOBISIIDAE, PSEUDOSCORPIONES): A NEW EPIGEAN SPECIES FROM EASTERN SERBIA

A single species of Roncus L. Koch, 1873, which was collected in eastern Serbia and is new to science (R. ivansticae n. sp.) is described herein; the diagnostic characters are illustrated and their distribution is provided. The possible establishment of two species (or supraspecific?) groups of Roncus is presented briefly in view of the importance of some diagnostic characters.


INTRODUCTION
Over the past four decades there has been a marked increase in our knowledge of the Neobisiidae of southeastern Europe (the Balkan Peninsula), and especially of the representatives of the genus Roncus L. Koch, 1873, which occur in leaf litter, soil and caves (Ćurčić, 1988; Ćurčić et al., 2004).Increased interest in the soil/litter and cave ecosystems, and improved sampling techniques have contributed to this knowledge.During a study of the ontogeny and postembryonic development of the pseudoscorpions in Serbia, one hitherto undescribed species of Roncus was found.
This paper provides descriptions of Roncus ivansticae n. sp., with some details of comparative morphology of this taxon.
All specimens are mounted on slides in Swan's fluid (gum chloral medium) and are deposited in the Institute of Zoology, Faculty of Biology, University of Belgrade, Belgrade, Serbia.
In the female, sternite II carries a group of 5 setae (which belong to two barely distinguishable groups).Sternite III carries 12 setae arranged uniformly in a single row on the posterior margin and 3 suprastigmatic microsetae on either side.Sternite IV has 8 posterior setae and 3 microsetae along each stigma.Sternite V has 13 setae, sternite VI -14, sternite VII -12, sternite VIII -14, sternite IX -13, and sternite X -12 setae.Sternite II with two pairs of tiny setae.
The form of the chelicerae is similar in males and females (Figs. 2 and 10); the tubercle of the movable cheliceral finger is a low hyaline convexity.The movable and fixed cheliceral fingers have a variable number of teeth with proximal and distal members of each series the smallest.The teeth of the movable finger end just below the galeal seta (gl).Six setae occur on the palm of the chelicera (Figs. 2 and 10).The cheliceral flagellum carries one short proximal blade and seven longer distal blades (Figs. 5 and 12).All are pinnate on at least the terminal half of the upper surfaces.The movable finger is longer than the cheliceral breadth (Table 1).In general, the chelicera is almost twice as long as broad (Table 1).
The manducatory process of the pedipalpal coxa carries 4 long setae.The pedipalpal femur is granulated anteriorly as are the interior and lateral parts of the pedipalpal chela (Figs. 1,3,9,and 11).These tubercles are absent on the pedipalpal tibia.
The movable finger of the pedipalpal chela carries 63 (male) and 49 (female) teeth, which are squaretopped in the proximal range of the series and are similar on the fixed finger.The form of the teeth on the fixed finger is variable (57 in female, 55 in male); the most distal pointed teeth, slightly asymmetrical, give way to teeth with rounded tops, and these are gradually replaced proximally by shorter flattened teeth.Four trichobothria are carried on the movable finger and eight on the fixed finger of the chela (Figs. 3 and 11).Four to seven small setae are found distal to the trichobothria eb and esb (Figs. 3 and 11).The pedipalpal femur is 3.50 (male) and 3.62 (female) times as long as broad (Table 1).This podomere is only slightly shorter than the carapace (Table 1).The pedipalpal patella (tibia) is 2.21 (male) and 2.11 (female) times as long as broad.The pedipalpal chela length-to-breadth ratio varies between 3.23 (female) and 3.50 (male).The chelal fingers are 0.69 (male) and 0.74 (female) times as long as broad.
Leg IV: the tibia, metatarsus, and tarsus each carry a long tactile seta (Figs. 8 and 14).The measurements of the different body structures and morphometric ratios are shown in Table 1.The tactile seta ratios exceed 0.50 (Table 1).
Remarks and discussion -The discovery of the described representative of Roncus in Serbia supports the fact that the taxonomy of this genus is still far from being complete (Ćurčić, 1972, 1984, 1988, 1992a, b;Ćurčić and Beron, 1981;Ćurčić et al., 1993, 2004, 2010a, b, c, d, e, f, g;2011a, b, c, d, e, f, g, h;Hadži, 1937).The variety of cave-dwelling species of Roncus described elsewhere by Ćurčić et al. (2004), offers further proof that this taxon is presently subjected to intensive radiation or divergent differentiation into new species.Furthermore, the diversity of Roncus representatives in the Balkan regions bordering on Serbia (Ćurčić, 1984;Ćurčić and Beron, 1981), compared to the same features in other areas, points to the Balkan Peninsula as a center of origin and genesis of numerous forms of the genus.In addition, the occurrence of numerous Roncus species with extremely limited distribution areas demonstrates their endemic nature.
With regard to two diagnostic characters, the presence/absence of microsetae proximal to eb and esb, and the presence/absence of one or two greater tubercles on the interior and lateral side of the pedipalpal femur, leads us to assume that the presence/ absence of these characters may be useful in distinguishing representatives of two or three species groups, respectively.It seems that both groups are widespread in Europe (Ćurčić et al., 1992a, b).However, although their precise taxonomic and biogeographic features are sufficiently known, the existence of two or three groups could point to their different taxonomic (generic?)status.
Material examined -One male and one female from oak and beech litter on the slopes of the river Ivanštica, Grza, near Paraćin, Eastern Serbia; 12 July 2009; collected by D. Z. Stojanović.