PSEUDOSCORPIONS FROM LAOS : DESCRIPTION OF A NEW SPECIES AND NEW RECORDS ( ARACHNIDA : PSEUDOSCORPIONES )

Pseudoscorpions collected from southern Laos, Champasak Province, are described. One new species of the family Chthoniidae Daday 1888 is identified and illustrated under the name of Tyrannochthonius etu sp. nov. Five species belonging to five family are reported from Laos for the first time: Apocheiridium pelagicum (Redikorzev, 1938), Lagynochthonius tonkinensis (Beier, 1951), Geogarypus longidigitatus (Rainbow, 1897), Nhatrangia dawydoffi Redikorzev, 1938, Indolpium funebrum (Redikorzev, 1938).


INTRODUCTION
To date, there are more than 3,454 pseudoscorpion species known globally (Harvey, 2011); according to our survey, it seems that there is a higher diversity in tropical and subtropical regions than other cold regions.Research into the pseudoscorpions of Laos has been neglected in the past; Beier was the first (and only) expert to report nine pseudoscorpion species from Laos, four of which were new to science (Beier, 1951).Comparison to adjacent regions can be made, thus 43 species belong to 13 families in Thailand, 62 species belong to 13 families in Vietnam, and 15 species belong to 9 families in Cambodia.Considering the high diversity of the tropical and subtropical regions, the number of pseudoscorpions (9 species) represents only a fraction of the true diversity in Laos.Therefore, further investigations into pseudoscorpions of Laos are required.
The symposium "Spiders of the Greater Mekong Region", organized by Peter Jäger (Germany), was held in Pakse, the capital of Champasak Province, southern Laos.This symposium aimed at promoting the research of Arachnida in this region and acted as a platform for the foundation of the Asian Society of Arachnology.We collected some pseudoscorpion specimens from Pakse and after examining, one species was recognized as new to science, Tyrannochthonius etu sp.nov., and the other five species are recorded from Laos for the first time.

MATERIALS AND METHODS
All specimens were collected and preserved in 75% alcohol and deposited in the Museum of Hebei University (MHBU), Baoding City, China.Microscopic examination and drawings were carried out with a Leica M165c stereomicroscope with a drawing tube.Photographs were taken with a Leica M205a stereomicroscope, which was also used for the measurements.Detailed examination was carried out with an Olympus BX53 general optical microscope.Temporary slide mounts were made in glycerol.The term "rallum" (for flagellum) follows Judson (2007).The pattern of description and terminology follow Chamberlin (1931) and Harvey (1992).All measurements are given in mm.
Lao terms: Phou = hill, Tad = waterfall (Peter Jäger et al, 2012) Remarks -This species was known only from Cambodia and Vietnam before, and it represents the first record of Cheiridiidae for Laos and expands its distribution.This species lives in a relatively dry environment.
Chthoniidae Daday, 1888 The Chthoniidae was first recognized as a distinct subfamily of pseudoscorpions by Daday (1888) and treated as a full family by Hansen (1894).Hitherto, it contains 27 genera.Members of the family Chthoniidae are distributed in most regions of the world, and mainly occur in leaf litter, soil, under rocks and stones; some are found within caves (Harvey, 2011).
The chthoniid genus Tyrannochthonius belongs to the tribe Tyrannochthoniini Chamberlin 1962, sub-family Chthoniinae Daday 1888, and it is a highly diversified genus in Chthoniidae.
To date, no species belonging to Chthoniidae has been recorded from Laos.Here two species are reported, Lagynochthonius tonkinensis (Beier, 1951) and Tyrannochthonius etu sp.nov.
Lagynochthonius tonkinensis (Beier, 1951) (Figs.3-4) This species was reported from Vietnam (Beier, 1951), and later known from China (Schawaller 1995) and Thailand (Schawaller 1994).It is a common species in the Oriental Region, and we presume that it is widely distributed in Southeast Asia.First record for Laos.Diagnosis -The new species is characterized by the following combination of characters: small size, four moderate eyes, anterior pair one diameter away from the posterior pair; carapace with a somewhat indistinct shield-shaped structure, slightly constricted posteriorly; chelal teeth homodentate.
Etymology -The specific name refers to the type locality.
Carapace slightly constricted posteriorly, with a somewhat indistinct shield-shape structure, broader than long, 18 setae, with 4 on anterior and 2 on posterior margins 4-2, 18; epistome present; with 4 eyes, anterior pair well developed and posterior pair with flattened lenses, anterior pair one diameter away from the posterior pair; setae P 4, I 2, II 3, III 4, IV 5; coxae I with finger-like apical projection, coxae II each with 8-9 terminally incised coxal spines.