New records of ant species from Yunnan, China

Abstract As with many other regions of the world, significant collecting, curation, and taxonomic efforts will be needed to complete the inventory of China’s ant fauna. This is especially true for the highly diverse tropical regions in the south of the country, where moist tropical forests harbor high species richness typical of the Southeast Asian region. We inventoried ants in the Xingshuangbanna prefecture, Yunnan, in June 2013, using a variety of methods including Winkler extraction and hand collection to sample ant diversity. We identified 213 species/morphospecies of ants from 10 subfamilies and 61 genera. After identification of 148 valid species of the 213 total species collected, 40 species represent new records for Yunnan province and 17 species are newly recorded for China. This increases the total number of named ant species in Yunnan and China to 447 and 951 respectively. The most common species collected were Brachyponera luteipes and Vollenhovia emeryi. Only one confirmed exotic species Strumigenys membranifera, was collected, although several others were potentially introduced by humans. These results highlight the high biodiversity value of the region, but also underscore how much work remains to fully document the native myrmecofauna.


Introduction
The understanding of regional and global patterns of insect diversity is limited by our incomplete accounting of Earth's species, especially for tropical regions where species richness peaks in most taxonomic groups. This is also true for Formicidae, an ecologically dominant insect family comprising at least 15,000 described species (Bolton 2014). Despite the ubiquity and ecological importance of ants (Hölldobler and Wilson 1990), many tropical regions remain undersampled even at the generic level . Compiling and curating complete and accurate species checklists for all regions of the world should be a priority in biodiversity research, especially for diverse insect groups.
Towards that end, here we present the results of an ant survey conducted during the summer of 2013 in the area of Xishuangbanna, Yunnan Province, in the south of China. In particular, our goal here is to document new records of ant species detected in Yunnan, and some new records for China as a whole. The geographic location of Yunnan (ranging from 21.15°N to 29.20°N of latitude) and its topography (elevation range from < 100m to 6740m) render it the most diverse province of China in terms of ant diversity (406 species) . The same is true for other taxa, such as plants (Li andWalker 1986, Mutke andBarthlott 2005), tiger beetles (Wu and Shook 2007), butterflies (Xie et al. 2009), or amphibians (Chen andBi 2007). Xishuangbanna prefecture is located in the tropical southwestern region of Yunnan province, bordering Laos and Myanmar, and has been identified as the most diverse region of Yunnan (Long 1995). The ant fauna of Xishuangbanna has been the subject of three studies (Xu 1998(Xu , 1999(Xu , 2002 and new species are regularly described from this prefecture (e.g. Guénard et al. 2013, Xu et al. 2014a. According to Xu's survey (2002), the myrmecofauna of Xishuangbanna consists of approximately 262 species, which constitute about 65% of the total number of species recorded for Yunnan province.
While elements of China's ant fauna may be undocumented due to a lack of sampling in certain geographic regions, there are many taxa likely hidden in areas that have been sampled historically. In particular, methods targeting specifically subterranean or leaf litter ants have been rarely used in China, which as a result might bias our detection of ant species from specific strata. One of the most successful sampling techniques for collecting leaf litter ants, Winkler extraction, which is now commonly used for ant fauna surveys all over the world (Olson 1991, Fisher 1999, Agosti et al. 2000, Martelli et al. 2004, Vasconcelos and Lopes 2008, Ivanov and Keiper 2009, has only been used once in China (Hong Kong in Fellowes 1996) to the best of our knowledge. In this study we used Winkler extraction as a standardized collection technique for the first time in order to survey the leaf litter ant fauna of Xishuangbanna. Based predominantly on this highly successful sampling technique, our diversity survey revealed 40 new species records for Yunnan including 17 new records for China. Here we present those new records, as well as their known global distributions by using data information aggregated by the Global Ant BioInformatics project (GABI, Guénard et al. in prep).

Material and methods
Ant specimens were collected from primary forest, secondary forest and rubber plantation habitats near Menglun town, Xishuangbanna Prefecture, Yunnan Province, China during a survey in June 2013. Ants from leaf litter of multiple sites were collected and extracted by mini Winkler extractors for 72 hours using the shuffling method as described in Guénard and Lucky (2011). Ants were also collected by hand on the ground, lower vegetation, and tree trunks.
Samples were first sorted to morphospecies in alcohol, and up to three representatives of each morphospecies per sample were point-mounted. Each mounted specimen was assigned a unique specimen code, in this case a CASENT number, and traditional locality and collection labels. All mounted and alcohol-preserved ant specimens are currently located in EPE's lab at the Okinawa Institute of Science and Technology Graduate University. Extended depth of field specimen images were taken with an incorporated Leica DFC400 digital camera mounted on a Leica M205C stereomicroscope through the Leica Application Suite V4 software. All specimens were identified to genus using Bolton's key (Bolton 1994), and then identified to species using available keys (see results section) as well as the digital resources on AntWeb (http://www.antweb.org). All the specimen data are freely available on AntWeb.
Species distributions presented in the following maps are based on records reported here at the country level, or for the larger countries (China, India, Japan), at the first administration level. For large islands (e.g. Borneo, Sumatra, New Guinea) that form natural biogeographic units, we used the island boundary instead of political boundaries similar to a previous study .

Results
Over 20000 specimens from 61 genera and 213 valid species and morphospecies were collected during this ant diversity survey (Table 1). A total of 40 new species records are presented for Yunnan province. Seventeen of these are recorded for the first time from China. The newly detected species belong to 15 genera from eight subfamilies. It is beyond the scope of the current paper to perform a comprehensive review/revision of the ant fauna of Yunnan Province, which would require much more geographically comprehensive sampling. Here, we present species accounts for the described ant species found during our survey that were previously unknown to Yunnan, supplementing other recently published checklists of the myrmecofauna of the region .
Taxonomic note. Aenictus artipus belongs to the Aenictus wroughtonii species group and can be easily identified with the identification key provided by Jaitrong et al. (2010). Natural history. Aenictus artipus has been collected from leaf litter in various habitats such as secondary forest and rubber plantation located near natural secondary forest. In addition, A. artipus has also been found in different habitats such as montane evergreen forest, savanna forest, evergreen forest and disturbed forest (Jaitrong et al. 2010).  Distribution. Widely distributed in the Indo-Malayan subregions ( Figure 2C). Taxonomic note. Aenictus hodgsoni belongs to the Aenictus laevicepss species group and can be easily identified with the identification key provided by Jaitrong and Yamane (2011).

Aenictus hodgsoni
Natural history. Aenictus hodgsoni has been collected from leaf litter and foraging columns on the forest ground in secondary forest. This species has also been found from lowland to highland in varied forest types (hill evergreen forest, dry evergreen forest, evergreen rain forest, mixed deciduous forest, and savanna) .   Distribution. Yunnan (new record), Vietnam and Thailand ( Figure 3C). Our material represents the northern-most record of Aenictus hodgsoni.

Aenictus maneerati Jaitrong & Yamane, 2013
Taxonomic note. Aenictus hodgsoni belongs to the Aenictus ceylonicus species group and can be easily identified with the identification key provided by Jaitrong and Yamane (2013). Natural history. Little is known about the bionomics of Aenictus hodgsoni. Before our survey, it has been only collected from primary forest (Jaitrong and Yamane 2013). We collected it from leaf litter in secondary forest.   Distribution. Yunnan (new record), Vietnam, Laos, and Thailand ( Figure 4C). This collection represents the northern-most record of Aenictus paradentatus.

Aenictus paradentatus
Taxonomic note. Aenictus paradentatus is very similar to Aenictus dentatus Forel, 1911, and can be easily identified with the key of Jaitrong et al. (2012).
Natural history. Aenictus paradentatus has been collected from foraging columns on the ground in limestone forest, but was also reported to be found in other forest habitats, ranging from primary forest to disturbed forest (Jaitrong et al. 2012).    Figure 5C). Taxonomic note. Aenictus thailandianus belongs to the Aenictus ceylonicus species group and can be easily identified with the identification key presented by Jaitrong and Yamane (2013).

Aenictus thailandianus Terayama & Kubota, 1993
Natural history. Aenictus thailandianus has only been found at higher elevations (1000-1500m) in primary and secondary forest (Jaitrong and Yamane 2013). We collected it from leaf litter and foraging columns on the ground in secondary forest and rubber plantations at lower elevations (under 1000m).  Distribution. Yunnan (new record) ( Figure 6C). Taxonomic note. Bannapone scrobiceps was described recently . Natural history. Little is known about the bionomics of Bannapone scrobiceps. The species was collected from leaf litter in secondary forest located at 550 meters elevation .   Figure 7C). Taxonomic note. Carebara melasolena can be identified with the key provided by Zhou and Zheng (1997;treated as Pheidologeton melasolenus) Natural history. Carebara melasolena has been collected from leaf litter in primary forest. Figure 8 Material Distribution. Discothyrea clavicornis is a very widespread and common species encountered throughout most of the Austral-Asian and Indo-Malayan subregions ( Figure  8C). This new record represents an important extension of the northern range in the distribution of this species.

Discothyrea clavicornis Emery, 1897
Taxonomic note. There is no available key for Discothyrea clavicornis. Our identification is based on the original description (Emery 1897), comparison with reference material, and montage images of the holotype provided by AntWeb.
Natural history. Discothyrea clavicornis has been collected from leaf litter in various habitats such as primary forest, limestone forest and rubber plantation.  Distribution. Yunnan (new record), Hunan, Okinawa ( Figure 9C). This new record represents an important western-most extension in the known distribution of this species.
Taxonomic note. Discothyrea kamiteta is very similar to the recently described Discothyrea banna Xu, Burwell & Nakamura, 2014. Both species seem to be very close morphologically, and their separation is based on minor differences, which could also be attributed to intraspecific variation. The identification is based on the original description of D. kamiteta, comparison with D. kamiteta material from the type locality (Okinawa), and Xu's key (Xu et al. 2014) Natural history. Discothyrea kamiteta has been collected from leaf litter in various habitats, such as primary forest, limestone forest and secondary forest.   Distribution. Yunnan (new record), Laos, Thailand ( Figure 10C). This collection represents the northern-most record of Dolichoderus laotius .

Dolichoderus laotius Santschi, 1920
Taxonomic note. There is no available key for the genus in the region. Our identification is based on the description provided by Dill et al. (2002). Natural history. Little is known about the bionomics of Dolichoderus laotius . This species has been collected on a tree trunk in secondary forest.   Distribution. Yunnan (new record) and Meghalaya ( Figure 11C). This new record represents an important northern and western extension in the distribution of Echinopla cherapunjiensis.

Echinopla cherapunjiensis Bharti & Gul, 2012
Taxonomic note. There is no available key for this genus. Identification is based on the original description (Bharti and Gul 2012). Natural history. Little is known about the bionomics of Echinopla cherapunjiensis. This species has been collected on a tree trunk in secondary forest.   Distribution. Yunnan (new record), Malaysia and Indonesia ( Figure 12C). This new record represents an important extension in the northern range of the distribution of this species and the first occurrence of the genus Gesomyrmex from Yunnan province.

Gesomyrmex kalshoveni Wheeler, 1929
Taxonomic note. There is no available key for this genus. The identification is based on the original description (Wheeler 1929) and comparison with reference material from Borneo. Identification in Gesomyrmex is generally very difficult due to the high degree of worker polymorphism. However, our single specimen is a minor worker and fits the minor workers of G. kalshoveni very well. Natural history. Little is known about the bionomics of Gesomyrmex kalshoveni. It has been collected from a small branch of a tree on the side of road. Distribution. Widely distributed in the Austral-Asian and Indo-Malayan subregions ( Figure 13C).
Taxonomic note. The identification is based on the key provided by Lattke (2004). The material from Yunnan shows some minor variation in the development of gastral sculpture, which we consider as geographic, intraspecific variation.
Natural history. Gnamptogenys costata has been collected from foraging columns on the ground in rain forest and limestone forest.  Taxonomic note. The identification is based on the key provided by Lattke (2004). Our material fits the holotype very well, except for the shape of the ventral process of the petiole, which is more rectangular in the material from Yunnan, whereas in the material from Borneo it is more triangular. Since this is the only difference we were able to observe, we treat it as intraspecific variation.
Natural history. Gnamptogenys treta has been collected from the leaf litter in rain forest, secondary forest and limestone forest and rubber plantation.  Distribution. Yunnan (new record) and Guangxi ( Figure 15C). This new record represents the western-most occurrence in the distribution of Myrmecina curvispina. Taxonomic note. The identification is based on the original description and the identification key given by Zhou et al. (2008).

Myrmecina curvispina
Natural history. Myrmecina curvispina has been collected from the leaf litter of various habitats such as rain forest, secondary forest and rubber plantation.  Distribution. Yunnan (new record), Guangxi and Hunan ( Figure 16C). This new record represents the western-most occurrence in the distribution of Myrmecina guangxiensis.

Myrmecina guangxiensis Zhou, 2001
Taxonomic note. Identification is based on the key provided by Zhou et al. (2008). Natural history. Myrmecina guangxiensis has been collected from leaf litter in rain forest, secondary forest and limestone forest.   Distribution. Widely distributed in the Indo-Malayan subregion ( Figure 17C). Taxonomic note. The identification of our material is based on Yamane's (2009) redescription of O. denticulata. Natural history. Odontoponera denticulata has been collected from the leaf litter in various habitats such as rain forest, secondary forest, limestone forest and rubber plantation.  Distribution. South China, Vietnam and Thailand ( Figure 18C). Taxonomic note. Pheidole hongkongensis can be identified with the identification key to northern Vietnamese Pheidole published by Eguchi (2008).
Natural history. Pheidole hongkongensis has been collected from leaf litter in secondary forest, limestone forest and rubber plantations. It has also been reported inhabiting the soil of woody gardens, forest edges and open areas (Eguchi 2008).  Distribution. Widely distributed in the Australasian and Indo-Malayan subregions ( Figure 19C).

Pheidole plagiaria Smith, 1860
Taxonomic note. Pheidole plagiaria can be identified with the identification key to Northern Vietnamese Pheidole provided by Eguchi (2008).
Natural history. Pheidole plagiaria has been collected from leaf litter from rain forest, limestone forest and rubber plantation. It has also been reported inhabiting in the soil of forest edge and open land (Eguchi 2008).  Distribution. Yunnan (new record), Vietnam, Thailand and Java ( Figure 20C). This new record represents the northern-most occurrence in the known distribution of Pheidole planifrons.

Pheidole planifrons Santschi, 1920
Taxonomic note. Pheidole planifrons can be identified with the identification key to Northern Vietnamese Pheidole provided by Eguchi (2008).
Natural history. Pheidole planifrons has been collected from leaf litter in rain forest, limestone forest and rubber plantations. It has also been reported inhabiting in the soil of forest edge and woody habitats (Eguchi 2008).   Distribution. Widely distributed in South China, Vietnam, Thailand and India ( Figure 22C).
Taxonomic note. Pheidole smythiesii can be identified with the identification key to Northern Vietnamese Pheidole provided by Eguchi (2008).
Natural history. Pheidole smythiesii has been collected from leaf litter from secondary forest. Eguchi (2008) reported the species to usually inhabit woody habitats and sometimes open areas where it nests in the soil. Pheidole smythiesii is also known to tend aphid colonies (Alfred and Agarwal 1990).  Distribution. Widely distributed in the Australasian and Indo-Malayan subregions ( Figure 23C).

Pheidole tumida Eguchi, 2008
Taxonomic note. Pheidole tumida can be identified with the identification key to Northern Vietnamese Pheidole provided by Eguchi (2008).
Natural history. Pheidole tumida has been collected from leaf litter in rain forest, secondary forest and rubber plantation. It has also been reported nesting in the soil and rotting logs of forest edges (Eguchi 2008). Distribution. Known from Yunnan (new record) and Vietnam ( Figure 24C). This new record represents the northern-most occurrence in the distribution of Pheidole vieti.
Taxonomic note. Pheidole vieti can be identified with the key given provided by Eguchi (2008).
Natural history. Pheidole vieti has been collected from leaf litter from rain forest, secondary forest and limestone forest. Distribution. Known from a few localities in China, Vietnam and Thailand ( Figure 25C).
Taxonomic note. Pheidole zoceana can be identified with the identification key to Northern Vietnamese Pheidole provided by Eguchi (2008).
Natural history. Pheidole zoceana has been collected from leaf litter in rain forest, secondary forest and rubber plantations. It has also been reported nesting in the soil of forest edges and mountainous area (Eguchi 2008).  Distribution. Known from Middle and South China ( Figure 26C). This new record represents the western-most record in the distribution of Prenolepis sphingthoraxa.

Prenolepis sphingthoraxa Zhou & Zheng, 1998
Taxonomic note. The identification is based on the original description (Zhou and Zheng 1998).
Natural history. Prenolepis sphingthoraxa has been collected from leaf litter in rain forest and little is known about its bionomics.  Distribution. Known from Yunnan (new record), Singapore, Thailand and Borneo ( Figure 27C). This new record represents the northern-most record in the distribution of Proceratium deelemani.
Taxonomic note. The identification of Proceratium deelemani is relatively straightforward with the key provided by Baroni Urbani and De Andrade (2003).
Natural history. Proceratium deelemani has been collected from leaf litter in rain forest, and little is known about its bionomics.   Taxonomic note. The identification is based on Bolton's (1992) key. Our material from Yunnan fits the re-description in the latter publication very well, even though the propodeal spines seem somewhat longer than in the material from Borneo. However, we consider this as a minor geographic variation.
Natural history. Recurvidris kemneri has been collected from leaf litter from rain forest, secondary forest and rubber plantation, and little is known about its bionomics. Figure 29 Material examined. CHINA, Yunnan, Xishuangbanna: XTBG (21.911°N, 101.283°E), Limestone forest, 06.vi.2013, 2 workers, 675m, Winkler sifting, B. Guénard, B. Blanchard and C. Liu. Distribution. Known from Yunnan (new record) and Borneo ( Figure 29C). This new record represents an important extension in the northern range of the distribution of Strumigenys dyschima.
Natural history. Strumigenys dyschima has been collected from leaf litter in limestone forest, and little is known about its bionomics.   Distribution. Widely distributed in Indo-Malayan subregions ( Figure 30C). Taxonomic note. Strumigenys kichijo can be identified with the identification key given by Bolton (2000;treated as Pyramica kichijo).
Natural history. Strumigenys kichijo has been collected from leaf litter in rubber plantations, and little is known about its bionomics. Figure 31 Material examined. CHINA, Yunnan, Xishuangbanna: "Holy Hills" (21.920°N, 101.239°E), Secondary forest, 07.vi.2013, 9 workers, 655m, Winkler sifting, B.  Natural history. Strumigenys nepalensis has been collected from leaf litter in rain forest, secondary forest, limestone forest and rubber plantations, and little is known about its bionomics.  Figure 33C). Taxonomic note. Strumigenys rallarhina can be identified with the identification key provided by Bolton (2000).

Strumigenys rallarhina
Natural history. Strumigenys rallarhina has been collected from leaf litter in rain forest and secondary forest, and little is known about its bionomics. (Forel, 1912) Figure 34C). Taxonomic note. Strumigenys sauteri can be identified with the identification key given by Bolton (2000;treated as Pyramica sauteri).

Strumigenys sauteri
Natural history. Strumigenys sauteri has been collected from leaf litter in rain forest and secondary forest, and little is known about its bionomics.   Distribution. Widely distributed in the Austral-Asian and Indo-Malayan subregions ( Figure 35C).
Taxonomic note. Technomyrmex pratensis is the only member of the Technomyrmex pratensis species group. It is a very conspicuous species within the genus, and its identification is very easy with the key provided by Bolton (2007).
Natural history. Technomyrmex pratensis has been collected from leaf litter in secondary forest, and little is known about its bionomics.   Distribution. Known form Yunnan (new record), northern India, and Vietnam ( Figure 36C).

Tetramorium difficile Bolton, 1977
Taxonomic note. Tetramorium difficile is a member of the Tetramorium tonganum group and can be identified with the key provided by Bolton (1977). However, T. difficile under its current definition is morphologically very close to T. tonganum. It is likely that both are conspecific and the material listed as T. difficile represents intraspecific forms of the very widespread T. tonganum. Natural history. Tetramorium difficile has been collected from leaf litter in secondary forest, and little is known about its bionomics.   Distribution. Known from Yunnan (new record), Vietnam, Thailand and Sri Lanka ( Figure 37C). This new record represents the northern-most record in the distribution of this species.

Tetramorium flavipes Emery, 1893
Taxonomic note. Tetramorium flavipes is a member of the Tetramorium tortuosum group. Its identification is relatively straightforward with the key given by Bolton (1977). However, T. flavipes, originally described from Thailand, is very close to T. eleates Forel, 1913 from Borneo and the Philippines, and as already pointed out by Bolton (1977), both could represent geographic variants of the same species.
Natural history. Tetramorium flavipes has been collected from leaf litter in secondary forest, and very little is known about its bionomics.  Distribution. Widely distributed in the Indo-Malayan subregion ( Figure 38C). Taxonomic note. Tetramorium parvispinum is a member of the Tetramorium walshi species group. It can be identified with the key presented by Bolton (1976;as Triglyphothrix parvispina) Natural history. Tetramorium parvispinum has been collected from leaf litter in secondary forest, limestone forest and rubber plantations, and little is known about its bionomics.  Distribution. Known from Yunnan (new record), Laos and Thailand ( Figure  39C). This new record represents the northern-most record in the distribution of Tetramorium polymorphum.

Tetramorium polymorphum
Taxonomic note. Tetramorium polymorphum is a member of the T. walshi species group. Its identification is not easy since the species was not known when Bolton (1976) published his revision of the genus Triglyphothrix (now Tetramorium), in which he provided keys to the Indo-Malayan and Austral-Asian T. walshi and T. obesum species groups. However, by combining Bolton's (1976) work with the recent species description of Yamane and Jaitrong (2011) the identification is relatively straightforward. It is very similar to the closely related and sympatric T. kheperra Bolton, 1976, and the identification key of Bolton (1976) will lead the user to that species. The recent addition to Bolton's key provided by Yamane and Jaitrong (2011) clearly separates both species.
Natural history. Tetramorium polymorphum is a very special member of the genus Tetramorium since it is the only known species that possesses a polymorphic worker caste divisible into distinctive minor, media and major workers . Yamane and Jaitrong (2011) also report that this species is comparatively aggressive and hypothesize that the major worker could have a defensive function. In addition, they emphasize that T. polymorphum is only found in undisturbed rain forest habitats in Thailand and Laos. Our data from Yunnan supports this since it was predominantly sampled from rain forest.  Distribution. Tetramorium tonganum is widely distributed in the Austral-Asian and Indo-Malayan subregions where it ranges from western Oceania to South East Asia ( Figure 40C). Bolton (1977) has noted already that the species is widespread in its native range and has the characteristics of tramp species. It is very likely that future collections will reveal its presence in more Chinese provinces Southeast Asian countries.

Tetramorium tonganum
Taxonomic note. Tetramorium polymorphum belongs to the Tetramorium tonganum group and can be easily identified with the key provided by Bolton (1977).
Natural history. Tetramorium polymorphum has been collected from leaf litter in secondary forest, and is known to be an exotic species in China (Guenard and Dunn 2012). Despite its wide distribution and tramping ability, there is very little information about its biology. In addition to Bolton (1977), Sarnat and Economo (2012) also confirm that T. tonganum is able to establish populations outside its native range without damaging or significantly altering ecological or agricultural systems in its introduced habitats. They also report that T. tonganum is mostly found on vegetation in disturbed or edge habitats.

Discussion
The total number of named ant species in China is 939, but the true species richness is expected to be significantly higher, perhaps as high as 1200 to 1600 species . The collection of these 40 new ant records for Yunnan and 17 for China through Winkler extraction, combined with the discovery of the extremely rare ant species Bannapone scrobiceps (Guenard et al. 2013), should encourage myrmecologists to consider leaf litter extraction as one of the primary methods to collect leaf litter ants, especially for places where this method has not previously been used. Nevertheless, further sampling methods that specifically target different strata will very likely yield additional species, which is especially true for hypogaeic and arboreal ant communities.
Based on our collections, many newly recorded species, such as Discothyrea clavicornis, Myrmecina curvispina, and Odontoponera denticulata are relatively common. The reason why those species were never reported from Yunnan before may be due to different collection techniques and/or misidentifications. For example, Odontoponera denticulata has long been misidentified as Odontoponera transversa (Yamane 2009). Another reason may be that some of the newly recorded species have been described only recently outside of Yunnan and/or China, such as Myrmecina curvispina and Pheidole tumida (Zhou et al. 2008, Eguchi 2008.
Many new species records in our collection such as Aenictus artipus, A. maneerati, A. paradentatus, Discothyrea clavicornis, Dolichoderus laotius, Gesomyrmex kalshoveni, Gnamptogenys treta, Pheidole plagiaria, P. planifrons, P. rugithorax, P. tumida, P. vieti, Recurvidris kemneri, Strumigenys dyschima, S. mitis, Tetramorium difficile, T. flavipes, T. parvispinum, and T. tonganum, are at the northern limit of their known distribution in Yunnan. Interestingly, the occurrence of several species in Yunnan, such as Discothyrea clavicornis, Gesomyrmex kalshoveni, Gnamptogenys treta, Recurvidris kemneri, and Strumigenys dyschima constitutes a disjunction from the rest of their known distribution in the Malay Peninsula. At present, it is unclear if these represent sampling artifacts and the ranges are actually continuous in the region, if these species ranges represent true biogeographic disjunctions, or if they are actually different species. Only future diversity inventories and taxonomic treatments, of which this paper represents one modest contribution, can answer these questions and further resolve the biodiversity map for ants and other organisms.
Despite the comparatively short collecting time we invested in the inventory of the myrmecofauna, we were able to identify 145 species, of which over 30% represent new records. This increases the list of known species for Yunnan by 10%, and there are still more than 60 species that we tentatively consider undescribed. This shows how little was previously known about the ant fauna of the region, and we are convinced that more intensive sampling in different habitats and microhabitats will likely reveal the presence of even more species or help improve the current taxonomic resolution. In this context, we think that Yunnan should be considered an area of high biodiversity value and deserving of attention of both biologists and conservationists. Regrettably, this interesting biota is being degraded at an alarming speed, particularly due to the rapid expansion of rubber plantations in the area (Li et al. 2007).