First data on spiders ( Arachnida : Araneae ) from dry dipterocarp forests of Thailand

Faunistic records of spiders in dry dipterocarp forests of Thailand are presented. Spiders were surveyed from November 2008 to December 2012. A total of 1,926 spider individuals were collected from 16 locations by visually searching, sweeping grasses and herb vegetation, beating shrubs and trees, and shifting leaf litters. Spiders were identified to 106 species in 86 genera of 29 families. The families Araneidae, Salticidae, Thomisidae, Tetragnathidae, and Theridiidae exhibited higher species richness. Several families that are rare and poorly known in Thailand were recorded, such as Stenochilidae, Eresidae, Idiopidae, Theraphosidae, and Nemesiidae. A faunistic overview of the spiders found in dry dipterocarp forest is presented. In general, the diverse composition of spiders and their guilds and the occurrence of rare and poorly known species in the Thai region confirm the high biotic value of dry dipterocarp forests. Continuing to maintain dry dipterocarp forest functions should be considered in future studies.

area.This forest type occupies dry sites in northern, northeastern, eastern, and western parts of the country where the elevation ranges from 150 m to 1,300 m above sea level, but the Dipterocarpaceae are generally more common at elevations below 1,000 m (Bunyavejchewin 1983;Murphy and Lugo 1986).Although variations in this habitat type in Thailand in terms of both conditions and elevation may provide a potential high diversity of spiders, little information about the spider fauna in the dry dipterocarp forests of Thailand has in fact been reported (Deeleman-Reinhold 2001;Murphy and Murphy 2000).Although the araneofauna of the Indochina region is beginning to be better explored-mainly in evergreen forests, agricultural fields, and mountain forests (e.g., Jäger 2007;Jäger andPraxaysombath 2009, Jäger andDankittipakul 2010;Jäger and Praxaysombath 2011)-arachnologists have rather neglected spiders in the dry dipterocarp forests of Thailand (Deeleman-Reinhold 2001).
This study aims to make a preliminary investigation of the diversity of spiders in Thailand's dry dipterocarp forests.Until now, only 480 species of spiders have been found from areas of Thailand during arachnological surveys in recent decades (World Spider Catalog 2016).Therefore, we anticipate that the recorded faunistic findings will significantly extend the knowledge of forest araneofauna in Thailand.

Study sites
The study was carried out across Thailand mainland area.Study sites were spread across 16 locations within dry dipterocarp forests in Thailand (Figure 1; Table 1).We gathered spider data, once for each study site, from November 2008 to December 2012 (particular sampling dates for every location are showed in Table 1).A handheld Global Positioning System receiver (Garmin Oregon 450) was used to determine the precise geographical Check List 12(6): 1996, 18 November 2016 doi: http://dx.doi.org/10.15560/12.6.1996ISSN 1809-127X © 2016 Check List and Authors

Species identification
All adult spider specimens were identified to family and species using existing identification keys wherever possible (Tikader 1980(Tikader , 1982; Barrion and Litsinger 1995;Daxiang et al. 1999;Murphy and Murphy 2000;Deeleman-Reinhold 2001;Jocqué and Dippenaar-Schoeman 2006;Jäger and Praxaysombath 2011).We used the hunting strategies proposed by Cardoso et al. (2011) to show guild structure of spiders in dry dipterocarp forests.The hunting strategies are sensing-web location and the altitude of each study location (Table 1).Examples of some study habitats of dry diptercarp forests are shown in Figure 2.  weavers, sheet-web weavers, space-web weavers, orbweb weavers, ambush hunters, other hunters, ground hunters, and specialists (Cardoso et al. 2011) Due to a lack of available identification keys for many families and the time required for conventional taxonomic work, a morphospecies approach was used to classify hardly identifiable species of spiders.Moreover, because of the difficulty involved in identifying juveniles, juvenile specimens were excluded from the determination and faunistical evaluation.Nomenclature and arrangement of families, genera, and species follow the most recent version of the World Spider Catalog (2016).
Voucher specimens (including identified adults and morphospecies unidentified to the species level) are deposited for further examination in the public collection of the Thailand Natural History Museum (Prathum Thani, Thailand).Samples are available on request at curator of Thailand Natural History Museum (Dr.Weeyawat Jaitrong) and at first author of this study (Prasit Wongprom).
A higher number of species in some genera found across different collecting locations were expected, especially in the wide geographical range of our study, but the identity of some species could not be defined, as some genera are taxonomically poorly known.These include specimens from the families Linyphiidae (Atypena spp.), Lycosidae (Hippasa spp.), Oonopidae (Ischnothyreus spp.), Theridiidae (Dipoena spp.), Zodariidae (Mallinella spp.), and Ochyroceratidae (genus undetermined).All voucher specimens are fully accessible at the deposition in museum for further studies.
Ambushers (10 species), sheet web weavers (7 species), space web weavers (6 species), and ground hunters (5 species) are the other common functional groups.Orb web builders dominated the material, represented (in descending order of abundance) by Cyclosa bifida (Doleschall 1859) (Figure 4A) (Araneidae), Nephila pilipes (Fabricius, 1793) (Figure 4B) (Nephilidae), Gasteracantha hasselti C. L. Koch, 1837 (Araneidae), and Leucauge decorata (Blackwall, 1864) (Tetragnathidae).All these species were found in high abundances within every studied dipterocarp forest.The Salticidae, the most abundant of the other hunt-  ers, were composed with the greatest number of genera (18 genera) in our collection.Among four common species of salticids (Table 3), Plexippus petersi (Karsch, 1878) (Figure 4C) represented the most abundant species from this family.Heteropoda venatoria (Linnaeus, 1767) (Figure 4D), from the family Sparassidae, was the second most abundant hunter.This species was recorded at every study location.It is usually found on bark of different tree species including dipterocarps from lowland to higland regions.It also commonly lives in houses and other synanthropic structures.
Most ambush hunters belonged to the Thomisidae, represented by the commonly found Amyciaea forticeps  Wongprom and Košulič | Spiders from dry dipterocarp forest of Thailand (O.P.-Cambridge, 1873), Camaricus sp. and Oxytate sp., while another family of ambush hunters (Selenopidae) was very rare.Among spider species in these common functional groups, a few species, such as Argiope pulchella Thorell, 1881 and Acusilas malaccensis Murphy & Murphy, 1983, were rare and found only in one or two sampling sites of dry dipterocarp forest stands (Table 3).The least common functional group that contained most of the rare species was sensing web builders.One genera of those rare specimens, (Prothemenops sp.), was found only in Sakaerat.In this location, we also found four other rare species (five or less individuals found) and the highest spider species richness and abundance specimens which were recorded during our arachnological research of dry dipterocarp forests (Table 3).

dIScuSSIOn
This faunistical study provides the first comprehensive compilation on spiders from dry dipterocarp forests in Thailand.The total of 29 spider families in Thailand's dry dipterocarp forests recorded from this study represented 25% of those families reported from around the world (World Spider Catalog 2016).The species richness in the study locations is rather high with structured guild composition, representing approximately 22% of the araneofauna in region of Thailand (Murphy and Murphy 2000;World Spider Catalog 2016).
Sakaerat was the site containing the highest species richness and spider abundance.This site was part of the Sakaerat Environmental Research Station (SERS) which have been recognized as one of five biosphere reserve in Thailand (UNESCO 2007).The forest area had been reported as improving in reduction of habitat degradation and higher forest restoration of dipterocarp forests (Trisurat 2010).Several not common and rare spider species with low distribution range found in this area had proved the importance of activities that help maintaining biotic value of forest stands in this biosphere reserve.
Among studied araneocenosis, we made several significant discoveries of poorly known and rare species of spiders.In the dipterocarp forests in the southern part of central Thailand (Huay Sai-Phetchaburi province) and northeastern part of Thailand (Sakaerat-Nakhon Ratchasima province), several specimens of Stegodyphus tibialis (Figure 5A and B) were found.This species was known to be distributed in India and Myanmar (Kraus and Kraus 1988), but there had been only one reported finding from Tak province, northwestern Thailand (Ono 1995).Therefore, the locations of the present records in Huay Sai and the Sakaerat indicate the southernmost and easternmost distribution range of this genus (Miller et al. 2012).Although the genus is known for its social manner of living (Johannesen et al. 2007), the present specimens were collected solitarily in typical nests found in grass undergrowth and their social behavior was not observed.
Other significant discoveries include the rare and poorly known species Argiope dang Jäger & Praxaysombath, 2009 (Figure 5C), which was found in the Sakaerat Biosphere Reserve in the northeastern part of Thailand.This species had been known only from Laos, where males and females had been found at several locations by Jäger and Praxaysombath (2009).Later, several specimens were collected in two locations in the central part of Thailand (Chotwong and Tanikawa 2013), so our finding is the second recording of this species within Thailand.Including our results, this species is now known from three locations in different habitats of Thailand (an agriculture field, an artificial garden, and a dipterocarp forest).Thus, we presume this species occurs more abundantly and in a variety of places and ecosystems within Thailand and more findings would be expected.Other significant discoveries include several specimens of the rare Selenopidae genus Siamspinops (Figure 5F) which were found in low abundances (n = 6) in six different locations.Representatives of the family Selenopidae are rather infrequently collected and especially poorly studied, mainly because they are confined to a specific microhabitat, i.e., the surface of large rocks and trunk of fallen trees (Deeleman-Reinhold 2000).Until now, only three species of genus Siamspinops are represented in Thailand (Dankittipakul and Corronca 2009).We provided only morphospecies as we have found only subadult females during our survey.
We also found several representatives of poorly known and uncommon spider families, namely Nemesiidae and Stenochilidae (Deeleman-Reinhold 2001; Murphy and Murphy 2000).These findings include species from the genera Damarchus (Figure 5E) and Colopea (Figure 5D).These representatives were found in low abundaces and at a few locations, mainly in the dipterocarp forest of Sakaerat and Takli.In general, specimens of Damarchus are not found commonly due to their natural history (trapdoor burrows) (Norma-Rashid and Li 2009).Stenochilids occur mainly in natural and seminatural conditions of undisturbed forest ecosystems (Murphy and Murphy 2000); however, there are also findings from disturbed agroecosystems such as physic nut plantations in rural human altered landscape (Košulič and Vichitbandha 2015).
In general, the rich composition of the spider fauna and the occurrence of some rare and uncommon species for the Thailand region confirm the biotic value of dipterocarp forest habitats and altogether significantly enhance knowledge of spiders in Thailand.However, future studies need to clarify how the diversity of spiders is structured along different gradients (e.g., disturbance, elevation, latitude, and seasonality) and what are the exact mechanisms affecting occurrence and function of spiders occurring in dipterocarp forests of Thailand (Michalko et al. in prep).
To conclude, we assume that these first results can  Table A1.Continued.

Figure 1 .
Figure 1.Map of sampling sites situated across 16 dipterocarp forest locations in Thailand (seeTable 1 for locality identification and coordinates

Figure 3 .
Figure 3. Guild composition of spiders in dry dipterocarp forests of Thailand.

Table 1 .
Table 1 for locality identification and coordinates according to numbering).List of selected study locations with coordinates, altitude and sampling dates.
Wongprom and Košulič | Spiders from dry dipterocarp forest of Thailand

Table 2 .
Summary of families with guild characteristic in dry dipterocarp forests of Thailand.

Table 3 .
Checklist of spider species and their abundances recorded in study location of dry dipterocarp forests.Families are sorted in alphabetic order.
ContinuedWongprom and Košulič | Spiders from dry dipterocarp forest of Thailand

Table A1 .
Wongprom and Košulič | Spiders from dry dipterocarp forest of Thailand Author contributions: Both authors equally carried out the survey, identified and preserved specimens, and wrote the manuscript.Voucher museum numbers of collected material which is deposited in public collection of Thailand Natural History Museum in Prathum Thani,