Phylogenetics and Species Delimitation of the Recluse Spider, Loxosceles rufescens (Araneae: Sicariidae) Populations Invading Bangkok, Thailand.

The Mediterranean recluse spider, Loxosceles rufescens, has been discovered for the first time inhabiting human dwellings in Bangkok, Thailand. Expeditions across 39 localities revealed five establishments with L. rufescens populations. The highest density was recorded in a storage house on Yaowarat Road, located in the heart of Bangkok's Chinatown, where 315 individuals were found, including adults, juveniles, and spiderlings. This medically significant spider's presence in such a densely populated urban area raises concerns about potential envenomation risks. Thirteen specimens of L. rufescens were extracted for DNA and sequenced for molecular phylogenetic analyses. COI and ITS2 markers were used to investigate relationships within L. rufescens and across available Loxosceles species sequences. Results indicate COI is superior for resolving species-level genetic clusters compared to ITS2. Surprisingly, L. rufescens individuals from the same house were found in significantly distant COI lineages, suggesting mtDNA may not be suitable for studying intra-specific phylogeography in this case. Species delimitation methods ABGD and ASAP demonstrated promising results for both COI and ITS2, while bPTP and GMYC tended to overestimate species numbers. ITS2 exhibited high sequence similarity in L. rufescens, suggesting potential utility as a barcoding marker for identification of this globally distributed species. Genetic distance analyses revealed a potential barcoding gap (K2P) of 8-9% for COI and <2% for ITS2 in Loxosceles. This study contributes valuable sequence data for the medically important genus Loxosceles and highlights the need for integrative approaches in understanding its evolution and spread. The findings have important implications for pest management strategies and public health in urban environments.

Integrative taxonomy uncovers a new Culicoides (Diptera: Ceratopogonidae) biting midge species from Thailand.

Fully understanding biodiversity often requires an integrated approach especially for small insects because species diagnostic morphological characters are limited. In this study, morphological characters and DNA barcodes were used to examine previously recognized genetically divergent lineages detected in the biting midge, Culicoides arakawae (Arakawa), from Thailand. Morphological examinations revealed that specimens belonging to one lineage are morphologically different from C. arakawae in shape of the paramere in males, and in the leg color pattern of both sexes. Therefore, a formal description is provided for this new species, Culicoides mahasarakhamense sp. nov. Based on morphological characters including a large and shallow palpal pit, one sac like spermatheca and male with parameres bent at base with large basal knob, the new species was assigned into the subgenus Meijerehelea Wirth and Hubert. Morphological differentiation including wing pattern and shape of spermatheca of the new species are discussed and compared with other members of this subgenus. Mitochondrial cytochrome c oxidase I sequence analysis indicated that this new species is different from other members of the subgenus Meijerehelea with minimum interspecific genetic divergence of 3.92%. Automatic Barcode Gap Discovery species delimitation analysis also supported the recognition of a new species. Phylogenetic analyses revealed that the new species is closely related to C. arakawae, consistent with morphological similarity of these species. Results of this study highlight the necessity of using integrated approach for Culicoides taxonomy.

The alderfly genus Indosialis Lestage, 1927 (Megaloptera: Sialidae) in Thailand and Laos, with a description of a new species.

Indosialis Lestage, 1927 is a small and rare megalopteran genus belonging to the family Sialidae and endemic to the Oriental region. The Thai and Lao species of Indosialis are herein revised by an integrative approach combining morphological and molecular evidence, including two species: Indosialis bannaensis Liu, Yang Hayashi, 2006 and Indosialis siamensis sp. nov. The pupal stage of Indosialis is reported here for the first time. Indosialis siamensis sp. nov. can be distinguished from its congeners by 1) the brown head and prothorax (orange in congeners); 2) the apical tooth of right mandible in male sharply angulated (truncate or almost absent in congeners); and 3) the distinct sac-like structure present in male genitalia (indistinct or absent in congeners). The new species coexists with I. bannaensis in Loei Province, northeastern Thailand. Both species inhabit slow-flowing or sluggish streams that are usually covered by Colocasia esculenta (L.) Schott (Araceae).

Description of nymphs and female subimago of Sparsorythus multilabeculatus Sroka Soldán, 2008 (Ephemeroptera: Tricorythidae) associated with male imago based on DNA sequence data.

Sparsorythus is a genus of Tricorythidae from the Oriental Region. Sparsorythus multilabeculatus Sroka Soldán, 2008 was described based on a male imago from Vietnam. Unknown nymphs and female subimagines of Sparsorythus and male imagines of S. multilabeculatus were collected from Thap Lan National Park, Khon Buri District, Nakhon Ratchasima Province, Thailand. Nymphs and female subimagines of Sparsorythus were associated with male imagines of S. multilabeculatus by analyzing sequences from the DNA barcoding region of the mitochrondrial gene cytochrome oxidase I. Phylogenetic analysis based on Maximum Likelihood indicated that all unknown specimens are conspecific with male imagines of S. multilabeculatus (bootstrap 100% and genetic distance 0-0.004). Male and female nymphs, female subimago and egg are described for the first time. Nymphs each bear a medial emargination on the hypopharynx, one bristle-like process at the base of the left prostheca, and a bifurcate rudimentary gill on abdominal segment VII. The male usually has smudges and light blotches on its forewings; the penis extends to the basal segment of the forceps and reaches to approximately 1/3 of the second segment of the forceps. Forewings of the female subimago have dark colour over more than half of the basal area, and the distal portion of each wing is translucent. The egg has a rounded pole; the polar cap covers approximately 1/4 of the surface; and the surface is covered with hexagonal structures.