A NEW TROGLOBITIC GROUND BEETLE ( CARABIDAE : TRECHINAE ) FROM EASTERN SERBIA

A new species of troglobitic trechine ground beetles is described from the Ceremošnja Cave in eastern Serbia – Duvalius (Paraduvalius) ceremosnjensis sp. n. All relevant morphological features of the new species are given and images of the new species are presented, along with the diagnosis with the closest relatives. The new trechine taxon is endemic to eastern Serbia.

Some karstic montane regions in eastern Serbia (especially the Homoljske Planine Mts.within the Carpathian mountain range), where potential new troglobitic ground beetle taxa may be discovered in the future, are still insufficiently explored.
Together with Prof. Guido Nonveiller, one of the authors of the present study (D.P.) visited the Ceremošnja Cave in the Homoljske Planine Mts. on 14 th June 1986.This visit was a part of investigations of endogean and cave-dwelling beetle fauna of Serbia, which were successfully implemented by Prof. Nonveiller during a few preceding years.The following year, i.e., on 22 th November 1987 we found in the same cave a left elytron of a trechine beetle for which we assumed to belong to Duvalius, a genus with a great number of lower taxa, which representatives inhabit caves and pits, but can also be found out of these, in thick humus layers and under stones, mostly in humid beech forests.Since then, one of the authors of the present study (D.P.) has been searching for a whole specimen of the trechine taxon, which elytron had previously been found in the Ceremošnja Cave.The mentioned author, accompanied with biospeleologist Siniša Ognjenović, went again to the investigated cave on 26 th November 2008 and finally collected one male of Duvalius belonging to the subgenus Paraduvalius.
Comparing the species with other Paraduvalius taxa known in Serbia, we concluded that the specimen from the Ceremošnja Cave belongs to a species new to science.The present paper contains a description and a diagnosis of a new trechine species.

MATERIALS AND METHODS
The collected trechine specimen was analyzed in the laboratories of the Institute of Zoology, University of Belgrade -Faculty of Biology, Belgrade, Serbia.The aedeagus was removed from the specimen and fixed on a microscope slide in a medium composed of Canada balsam and xylol.The type specimen was then glued onto a rectangular paper card and analyzed as dry individual.All taxonomically important morphological features were studied for comparison.A Carl Zeiss Stemi 2000 and a Carl Zeiss SteREO Discovery.V8 binocular stereomicroscopes and a Carl Zeiss Axioskop 40 microscope were used in this study.Etymology: The new species is named after the Ceremošnja Cave, the terra typica.
Description: Large-sized.Total body length (from anterior margin of clypeus to apex of elytra): 6.29 mm.Body elongated, covered with densely distributed pubescence (Fig. 1).Body color is yellowish.
Head large, rounded (Fig. 1), wider than it is long [ratio of maximum width to length of head (from anterior margin of clypeus to posterior end of genae): 1.19].Frontal furrows deep, complete, arcuated, the deepest in anterior half.Cheeks convex, covered with short erect hairs.Eyes quite reduced, oval, with a pigmented border, and with no ommatidia.An arcuated pre-ocular furrow is present.Mentum tooth is bifid.Antennae of moderate length (total antennal length including scape: 4.35 mm), exceeding slightly over middle part of elytra.Antennomere II shorter than antennomere IV.Ultimate antennomere four times as long as it is wide.
Pronotum of medium size (Fig. 1), slightly transverse [ratio of maximum width to length of pronotum (along median line): 1.15], sub-cordate, widest between anterior fifth and fourth, slightly wider than head (ratio of maximum width of pronotum to Elytra elongated, obovoid (Fig. 1), ratio of length (linear distance along suture from elytral base to apex) to maximum width of elytra: 1.76, widest slightly prior to middle, ratio of length of elytra (linear distance along suture from elytral base to apex) to length of pronotum (along median line): 3.30, ratio of maximum width of elytra to maximum width of pronotum: 1.65.Shoulders rounded, obtuse, sloped.Elytral apex rounded.Marginal furrows relatively wide and deep.Elytral disc convex.Four innermost striae developed, well impressed.Outer striae weakly developed, present in form of rows of punctures.Inner intervals convex.
Chaetotaxy (Fig. 1): two pairs of supra-orbital setae on head.Two pairs of setae on pronotum, of which first pair is located between anterior fifth and fourth of pronotal length, while second pair situated in hind pronotal angles.Each shoulder with four setae.The longest distance is between second and third setae, while distances between first and second setae and third and fourth setae equal and somewhat shorter.Second seta is right next to elytral marginal furrow.First, third and fourth setae away from the furrow.Elytra with two pairs of discal setae.First pair of elytral discal setae situated in fourth interval, close to third stria, slightly below anterior fourth of elytral length, at the level below fourth humeral seta.Second pair of elytral discal setae situated on third stria, slightly below three-fifths of elytral length.
Aedeagus large, dorsally slightly convex in basal part in lateral view (Figs.2a and 2b).Median lobe straight and with sub-parallel sides in lateral and dorsal views, with a pointed apex directed downwards in lateral view (Fig. 2b), while apex being triangular in dorsal view (Fig. 2a).Basal bulb massive in lateral view, rounded (Figs.2a and 2b).Paramerae of moderate width, gradually narrowing apically, each with four setae (Figs.2a and 2b).Copulatory piece elongated, as long as median lobe, strongly sclerotized, unifid, gutter-formed, moderately widened sub-basally, with a pointed apex (Figs.2a and 2b).
Female genitalia unknown.
Diagnosis: Duvalius (P.) ceremosnjensis sp.n. belongs to the "stankovitchi" group of species (according to Guéorguiev, 1971) based on the shape of elytra, presence of unpronounced shoulders (rounded, not angled), absence of recumbent pubescence on vertex, presence of a longitudinal fissure on fore tibiae and position of first elytral discal setae (located below the level of third humeral setae).
The new species clearly differs from all relative congeners within the "stankovitchi" group living in a few caves in eastern Serbia.These are Duvalius (Paraduvalius) stankovitchi (Jeannel, 1923) (Jeannel, 1923(Jeannel, , 1928;;Ćurčić et al., 2014a, 2014b).Duvalius (P.) ceremosnjensis sp.n. and the three abovementioned species have a similar shape of aedeagus and copulatory piece, but there are numerous distinctions between the new species and the closest relatives.
Duvalius (P.) ceremosnjensis sp.n. differs from D. (P.) stankovitchi by its greater total body length (from anterior margin of clypeus to apex of elytra) (6.29 mm vs. 5.00-6.20 mm), ratio of maximum width to length of head (from anterior margin of clypeus to posterior end of genae) (head wider than it is long vs. head as wide as it is long), length of antennae (exceeding slightly over middle of elytra vs. not reaching middle of elytra), ratio of maximum width to length of pronotum (along median line) (pronotum wider than it is long vs. pronotum longer than it is wide), position of maximum width of pronotum (between anterior fifth and fourth vs. about anterior third), ratio of length (linear distance along suture from elytral base to apex) to maximum width of elytra (1.76 vs. 2.00), position of first pair of elytral discal setae (at the level below fourth humeral seta vs. at the level of fourth humeral seta), shape of aedeagus in lateral view (apex of median lobe gradually narrowing distally, basal bulb larger, rounded basally vs. apex of median lobe abruptly narrowing distally, basal bulb smaller, somewhat constricted basally) and shape of apex of copulatory piece in dorsal view (pointed vs. rounded) (Jeannel, 1923(Jeannel, , 1928)).
Duvalius (P.) ceremosnjensis sp.n. can be distinguished from D. (P.) petrovici by its much greater total body length (from anterior margin of clypeus to apex of elytra) (6.29 mm vs. 4.12-4.65 mm), shape of eyes (oval vs. in form of a line), ratio of antennomere XI length to width (4.00 vs. about 3.00), shape of elytra (obovoid vs. ovoid), ratio of length (linear distance along suture from elytral base to apex) to maximum width of elytra (1.76 vs. 1.71), position of maximum width of elytra (slightly prior to middle vs. between middle and three-fifths of length), shape of shoulders (rounded, sloped vs. obtuse-angled, elevated), position of first pair of elytral discal setae (at the level below fourth humeral seta vs. at the level between third and fourth humeral setae), shape of aedeagus in lateral (apex of median lobe directed downwards, median lobe with sub-parallel sides, basal bulb less elongated, more rounded vs. apex of median lobe straight, median lobe gradually narrowing apically, basal bulb more elongated, less rounded) and dorsal views (more elongated, median lobe with a more pointed apex vs. less elongated, median lobe with a less pointed apex) and shape of copulatory piece in dorsal view (subbasally widened vs. gradually narrowing apically) (Ćurčić et al., 2014a).
Duvalius (P.) ceremosnjensis sp.n. clearly differs from D. (P.) beljanicae by its greater total body length (from anterior margin of clypeus to apex of elytra) (6.29 mm vs. 4.05-4.59mm), ratio of antennomere XI length to width (4.00 vs. about 3.00), shape of hind pronotal angles (acute vs. obtuse), shape of elytra (obovoid vs. ovoid), ratio of length (linear distance along suture from elytral base to apex) to maximum width of elytra (1.76 vs. 1.71), position of maximum width of elytra (slightly prior to middle vs. below middle), shape of shoulders (sloped vs. elevated), number of well-developed striae on each elytron (four vs. two), position of first (slightly below anterior fourth of elytral length vs. slightly above anterior third of elytral length) and second pairs of elytral discal setae (slightly below three-fifths of elytral length vs. about at two-thirds of elytral length), shape of aedeagus in lateral (median lobe with sub-parallel sides, abruptly narrowing apically, apex more bent downwards, basal bulb more massive vs. median lobe gradually narrowing apically, apex less bent downwards, basal bulb less massive) and dorsal views (more elongated, median lobe with sub-parallel sides and a pointed apex vs. less elongated, median lobe somewhat widened basally, with a rounded apex) and shape of copulatory piece in dorsal view (sub-basally widened, pointed apically vs. medially widened, rounded apically) (Ćurčić et al., 2014b).

DISCUSSION
The Ceremošnja Cave is located on the northeastern slopes of the Homoljske Planine Mts., about 15 km from the town of Kučevo.The total length of all explored tunnels is 775 m.The cave contains three groups of channels: dry, inflow and periodical.Geologically, belongs to the inflow type of caves.The Strugarski Potok stream is flowing into the cave and continues its flow further underground, so the lowest parts of the cave are submerged for most part of the year (Đurović, 1998).
The type specimen of D. (P.) ceremosnjensis sp.n. was collected by pitfall trapping with rotten meat as bait in the middle, totally dark part of the Ceremošnja Cave characterized by a high level of humidity (presence of trickling water).The trap was positioned in the inflow chamber (active gallery) of the cave, in the vicinity of an underground stream (Strugarski Potok) (Đurović, 1998).
On several occasions after the only finding, attempts were made to collect more specimens of the new trechine beetle (both manually and by pitfall trapping) within the Ceremošnja Cave and a number of cave and endogean sites in the vicinity, however no additional efforts were successful.Therefore, we can consider the species quite rare.
The new troglobitic trechine ground beetle species is endemic to the Carpathian mountain system in eastern Serbia.The new species is the first known Duvalius (Paraduvalius) taxon from the Homoljske Planine Mts., representing the northernmost finding of Duvalius spp. in eastern Serbia.