Identity and identification of Trogulus banaticus ( Opiliones : Trogulidae ) – a neglected species in the Northern Balkans

Trogulus banaticus Avram, 1971 is characterised and recorded as new for Slovenia. This species was previously mistaken for T. coriziformis C. L. Koch, 1839 and T. graecus Dahl, 1903 which were later rejected from the Slovenian fauna. T. banaticus is compared with the similar, and partly sympatric, T. tingiformis C. L. Koch, 1847 with which it has often been confused. A table of distinguishing characters for both species is provided, and the ecology of T. banaticus and its general distribution are discussed.

The genus Trogulus Latreille, 1802 has long been known to be a problematic group in terms of taxonomy and species delineation (MARTENS 1988).
Recent integrative studies incorporating molecular, morphological and biogeographical data (SCHÖN-HOFER & MARTENS 2008, 2009, 2010) revealed a large number of cryptic species necessitating clear definitions of already described species.Yet many descriptions were insufficient causing species to be neglected in research on Opiliones in Central Europe.This was the case of Trogulus species described by AVRAM (1971), several of which were based upon one or only a few specimens and accompanied by hard/difficult to understand taxonomic drawings.Of Avram's six new species, three were assumed to be based on defective specimens with a broken glans stylus.MARTENS (1978) therefore synonymised T. gruberi Avram, 1971 with T. tingiformis C. L. Koch, 1847 andWEISS (1978) supposed the same defect for T. galasensis Avram, 1971 andT. roeweri Avram, 1971 which he referred to T. nepaeformis (Scopoli, 1763).Apart from this substantial criticism, the remainder of Avram's species were treated slightly more positively.Because of the poor drawings and the assumed high variability in Trogulus species, MARTENS (1978) synonymised Trogulus closanicus Avram, 1971with T. nepaeformis, and T. oltenicus Avram, 1971with T. tricarinatus (Linnaeus, 1767).It was WEISS (1978), in possession of a rich material from Podu Olt in Romania, who confirmed the validity of both Avram species based on a morphometric analysis.Later on, CHEMINI (1984) re-described T. closanicus, which is the only one of Avram's species that became widely accepted and cited in literature, while T. oltenicus still suffers from having little attention due to the lack of a sound re-description and its unknown geographic distribution in southern Romania.
Yet, there is another of Avram's species, Trogulus banaticus Avram, 1971 that still lacks a clear statement concerning its validity.WEISS (1978) questioned the description as based on only a single male.WEISS (1996) mentioned T. banaticus from North-eastern Romania but commented on this record being located far from the type locality and the general need for Trogulus revisions.Recently, it was listed by BA-BALEAN (2004,2005) in checklists of the Romanian fauna, without further comment.Although the Avram types were not available from the Bucharest Museum, investigation of a comprehensive collection of Trogulus material from Europe yielded an understanding what Avram actually perceived as T. banaticus.We therefore were able to use the name in previous contributions, prior to a re-description (SCHÖNHOFER & MARTENS 2008, 2009, 2010).
Here, we aim to outline the important characteristics to identify the species and to delineate it from the sympatric T. tingiformis which is of comparable body size and similar morphological key characters.Reasons why T. banaticus was neglected for so long are discussed, and a brief overview of its distribution and ecology is given.Detailed data are provided for Slovenia and an outline of the assumed distribution based on already confirmed records is shown (Fig. 1).A full description for T. banaticus listing all records is intended within a revision of the Trogulus torosus species group, for which the investigation of material is still in progress.

Material and methods
Material discussed is deposited in the working collections of Jochen Martens in the Institute of Zoology, Mainz University, Germany (Collection J. Martens: CJM) and Tone Novak and Ljuba Slana Novak, Slovenj Gradec, Slovenia (Collection Novak and Slana: CNS) and the Naturkunde Museum Berlin (ZMB, Jason Dunlop).The geodetic reference date used was WSG84.

Further records shown in
Resulting drawings were vectorised using a Wacom Bamboo tablet CTH-460 and Inkscape 0.48.Photographs of specimens were taken with a Nikon D80 attached to the M5A, and refined with CombineZP and Photoshop CS4.

Results
The identification of Trogulus banaticus was based on material collected close to the type locality in Romania (CJM 4927) and re-evaluation of the original description by AVRAM (1971).The main differences between Trogulus banaticus and T. tingiformis which enable easier identification of these partly sympatric -and frequently confused -species are listed in Table 1.

Diagnosis of Trogulus banaticus Avram, 1971
Figs. 4-7, 12-17, 19-20, 22 Medium-sized to large Trogulus (body size  (n=36): 7.65-9.55, (n=30): 9.55-11.64;Figs 5, 7) with broad and compact body of a brown to dark brown coloration with blackish tinge (specimen shown are bleached in alcohol); legs short, stout, segments of tarsus II equal in length 22); conspicuous dorsal papillation pattern (clearly seen in Fig. 4), ridges, especially the median one, elevated or even strongly elevated; hood large with respect to body length (male body length/length of hood = ~6.5;Figs 4-7), rhombic to rounded, with branches continuous narrowing distad, shaping area of inner papillation roughly triangular to round triangular; eyes and eye mound large and elevated; eyes large, with wide black surrounding field; suture between pro-and opisthosoma bent in a wide curve to opisthosoma; hind end of opisthosomal plate strongly bent dorsad.
Base of penis (Figs 12-15) drawn out in two root-like structures, truncus constricted above the base, then gradually widening towards the middle and then tapering without remarkable intersection or bump into the glans; glans very slender and elongated, tapering into the narrow stylus.Stylus in straight elongation with the truncus, blunt, with shallow dorsal groove tapering proximad, bent laterad in distal part and ending as a small rectangular tip.

Discrimination from Trogulus tingiformis
Trogulus tingiformis and T. banaticus distributional areas broadly overlap in Romania, where they are partly syntopic (Bistriţa, WEISS 1996).In Slovenia they appear to be sympatric and often syntopic (Runarsko) in its limited southern part -the north-easternmost area of T. banaticus.Other records of T. tingiformis overlapping the area we presume here for T. banaticus have been published by AVRAM (1971, sub gruberi;MARTENS 1978), yet many of the authors did not discriminate between the two species or ignored T. banaticus altogether.The identification of Trogulus species has often been reduced to investigations of body size and the relative lengths of the articles of tarsus II.As these characters are very similar in T. tingiformis and T. banaticus, the two species may thus be easily confused.We therefore provide a number of Tab.1: Diagnostic differences between Trogulus banaticus and T. tingiformis.Receptaculi seminis are very similar in both species and these differences are therefore not elucidated here.

Trogulus banaticus Trogulus tingiformis
proportion of head cap to body small, i.e. relatively large head (Figs 5,7) proportion of head cap to body large, i.e. relatively small head (Fig. 3) lateral borders of prosoma clearly concave (Figs 4, 6) lateral borders of prosoma straight (Fig. 2) or scarcely concave area of median papillae of hood roughly triangular to rounded triangular (Fig. 4, 6) area of median papillae of hood elongated elliptic or rhomboid (Fig. 2) abrupt change of papillation density from central median ridge to surrounding area (clearly seen in Fig. 5) gradual to no change of papillation density from central median ridge to surrounding area (Fig. 3) body colour dark brown with blackish tinge (specimen shown bleached) body colour brown with reddish tinge (Fig. 3) body and legs broad (Figs 5, 7) body and legs more slender (Fig. 3) suture between pro-and opisthosoma in midsection strongly bent to opisthosoma (Fig. 4) suture between pro-and opisthosoma nearly straight, only slightly bent (Fig. 2) hairs on legs straight, pointing more dorsad than distad, longer 22) hairs on legs bent at a low angle to distad, often blunt and inconspicuous, shorter (Fig. 21) distinct y-shaped ridges on prosoma (Fig. 4) prosoma without a distinct papillation pattern (Fig. 2) stylus of penis slightly bent dorso-laterad (Fig. 12-13) stylus of penis bent dorsad in total length (Fig. 8-9) truncus of penis constricted above base and widened in midsection (Fig. 15) truncus of penis more or less parallel sided (Fig. 11) palpus very large and elongated (Figs 16-17) palpus small, segments stout (Fig. 18) differential characters (Table 1) to enable discrimination.

Ecological and biogeographical remarks on T. banaticus
The few detailed records, mainly from our own collections, show Trogulus banaticus inhabiting deciduous forests over calcareous bedrock.While this is an environment favoured by many Trogulus species, T. banaticus seems to require special microhabitats.So far, most described habitats feature a rocky surface layer, often composed of multiple layers of stones, allowing transit through their interstitial system.Here T. banaticus is found in the humidity-saturated loamy parts.In view of other members of the Trogulus torosus species-group, a preference for cool microhabitats seems to be a common requirement.In Slovenia, a record from a cave wall (Albeljska jama) a few meters below the surface during the hot summer days is highly consistent with these findings, while deep beech litter localities (Travni Dolci, Ograja)

Discussion
Comparing the original description (AVRAM 1971) with this new material, T. banaticus appears to be easily recognisable within the European set of Trogulus species.In spite of its large distribution area (Fig. 1) it remained un-entangled for such a long time for reasons explained in the introduction, and because of the complex faunal setting along the Balkans, accompanied by misidentification of other similar Trogulus species.For example T. banaticus material from Bosnia and Herzegovina, Serbia, Macedonia and Montenegro was misidentified as T. tingiformis (KARAMAN 1995, ĆURČIĆ et al. 1999)
Genetic divergence estimated from direct comparison of 552 bp cytochrome b sequences of the series CJM 4317, 4840 and 4927 show a divergence of ~1 % between the sequences of these individuals, pointing to low intraspecific and geographic variation between T. banaticus from Romania, Serbia and Macedonia (SCHÖNHOFER & MARTENS 2010).
indicate that bare, loamy substrates might be preferable only in places where other cold and wet habitats are missing or, on the other hand, these are just places where species of the genus Trogulus can more easily be noticed.In any case, in the north-westernmost part of the area in Slovenia, the occurrence in deep litter might be a false experience for the sparse number of investigated localities.
T. banaticus overlaps the Dinaric area part of the T. falcipenis clade (SCHÖNHOFER & MARTENS 2008), always following the main mountain chains which provide the necessary lithoclastic habitats.
(NOVAK et al. 2006ENS 2008)e became apparent, they were formally referred to T. graecusDahl, 1903, due to general similarities with this species.In Slovenia -which displays a transition zone between Mediterranean, Alpine and Dinaric faunas -even more possibilities to misidentify T. banaticus arose.According to the first mapping, T. coriziformis C. L. Koch, 1839 was also alleged for Croatia(MARTENS 1978, NOVAK 2004)and, based upon a juvenile specimen (CJM 1617),NOVAK et al. (1995)and NOVAK & GRUBER (2000, sub T. cf.coriziformis) erroneously listed the species for Slovenia.Therefore the first record of T. banaticus from Slovenia (Runarsko) was informally given as belonging to T. coriziformis; a species now excluded from the Slovenian (NOVAK 2005b) and Croatian fauna, supported by the revision of the associated species group(SCHÖNHOFER & MARTENS 2008).Afterwards the Slovenian records were affiliated with the T. graecus species group(NOVAK et al. 2006).Yet, the records associated with T. graecus remained questionable, as the habitat and distribution seemed an inappropriate match for this xerothermic species with a far more southern Balkan distribution.NOVAK (2005a) refuted the presence of T. graecus in Bosnia.Finally, newly collected material of Trogulus banaticus (CJM 4927) from the terra typica in Romania has enabled a reinterpretation of Avram's species.Molecular investigation confirmed this series to be conspecific with other specimens from Romania (CJM 4317) and Southern Serbia(CJM 4840; cf.SCHÖNHOFER & MARTENS 2010).This enabled us to revise the records of T. graecus in the Central and Northern Balkans, including Slovenia, and to assign most of them to T. banaticus.At this point Ingmar Weiss has to be credited, because he, in 1996, already recognised differences between syntopic T. tingiformis and T. banaticus in Romania.