The segmented spider family Liphistiidae is the most basal family among living spiders. These spiders can be differentiated from other spiders by the retention of several spider plesiomorphic characteristics, such as the presence of abdominal tergite plates and the presence of spinnerets on the median area of the abdomen. Liphistius Schiödte, 1849 is endemic in southeast Asia. Liphistius includes 69 described species placed in seven species groups based primarily on genitalic characters. In Thailand, there are 39 Liphistius species in four species groups including the birmanicus-group, the bristowei-group, the linang-group, and the trang-group. In addition, the large trang-group has been subdivided into six species complexes. However, there is lack of consensus concerning phylogenetic relationships at the species and species-group levels. This study sampled 162 Liphistius specimens from 52 collecting sites in Thailand and Myanmar. We used five nucleotide loci (mitochondrial COI and 16S, and nuclear H3, 28S, and ITS2) to reconstruct phylogenetic relationships, infer historical biogeography, and delimit Liphistius species. The concatenated alignments include 2,011 bps (COI: 168 sequences, 550 bps, 16S: 168 sequences, 316 bps, H3: 146 sequences, 241 bps, 28S: 159 sequences, 630 bps, and ITS2: 161 sequences, 245 bps). Phylogenetic results are primarily congruent with morphology-based classifications, in supporting the monophyly of the genus, the bristowei-group, and the trang-group. However, our results do not support the monophyly of the six species complexes within the trang-group. Ancestral area reconstruction suggested Liphistius originated in Sibumasu and diversified into several species-groups via dispersal and vicariance processes during the early Eocene (50–53 MA). Most taxa found in Thailand belong to the bristowei- and the trang-groups. The bristowei-group originated in the area that corresponds to their current distribution in the northwestern mountain range of Thailand during the late Eocene (33 MA). The large trang-group originated in the Thai-Malaysian peninsula during the mid-Eocene (47 MA) and diversified into five monophyletic clades in the late Eocene and the mid-Miocene (17–41 MA). Three of which diversified inhabited the same area. The two remaining clades crossed the isthmus of Kra, one clade distributed northward and inhabited mainland Sibumasu while the other distributed eastward and colonized Indochina during the early Oligocene (31–32 MA). The species delimitation results (ASAP, GMYC, PTP, STACEY, and BFD) delimited specimens from discrete locations as separate species; variation in number of species proposed (53 to 72) stemmed from variation in delimitation of sympatric cryptic species.
Molecular phylogeny, biogeography, and species delimitation of segmented spider genus Liphistius (Araneae: Liphistiidae) in Thailand