Diversity and antimicrobial activity of the tropical ant-derived actinomycetes isolated from Thailand.

Antibiotic resistance is one of the most important global healthcare challenges and is responsible for the mortality of millions of people worldwide every year. It is a crisis attributed to misuse of antibiotics and a lack of new drug development. Actinomycetes constitute a group of Gram-positive bacteria known for their distinctive high guanine-cytosine (G+C) content in their genomic DNA. These microorganisms are widely recognized for their capability to generate a wide range of secondary metabolites with diverse biological activities. These versatile microorganisms are ubiquitous in diverse ecosystems, including soil, freshwater, marine sediments, and within the bodies of insects. A recent study has demonstrated that social insects, such as ants, host a diverse array of these bacteria. In this study, we involved the isolation and characterization of a total of 72 actinomycete strains obtained from 18 distinct ant species collected from various regions across Thailand. Utilizing 16S rRNA gene analysis, these isolated actinomycetes were classified into four distinct genera: Amycolatopsis (2 isolates), Micromonospora (1 isolate), Nocardia (8 isolates), and Streptomyces (61 isolates). Among the Streptomyces strains, 23 isolates exhibited antimicrobial activity against a panel of Gram-positive bacteria, including Bacillus subtilis ATCC 6633, Staphylococcus epidermidis ATCC 12228, Staphylococcus aureus ATCC 25923, Kocuria rhizophila ATCC 9341, and Methicillin-resistant Staphylococcus aureus (MRSA) DMST 20646. Additionally, two isolates displayed antifungal activity against Candida albicans TISTR 5554. Based on 16S rRNA gene sequence similarity studies, these two isolates, ODS25 and ODS28, were demonstrated to be closely related to Streptomyces lusitanus NBRC 13464T (98.07%) and Streptomyces haliclonae DSM 41970T (97.28%), respectively. The level of 16S rRNA gene sequence similarity below 98.65% cutoff indicates its potential as a novel actinomycete species. These findings underscore the potential of actinomycetes sourced from ants as a valuable reservoir of novel antimicrobials.

The ant subgenus Campomyrma of the genus Polyrhachis Smith, 1857 (Hymenoptera, Formicidae, Formicinae) in Thailand and Laos, with descriptions of two new species.

The subgenus Campomyrma Wheeler, 1911 of the genus Polyrhachis Smith, 1758 in Thailand and Laos is reviewed. Four species are recognized, of which two are described and illustrated as new to science based on the worker and dealate queen under the names Polyrhachis quadrispinosa Jaitrong & Noon-anant, sp. nov. (found in a dead twig on a rubber tree) and P. lao Jaitrong & Yamane, sp. nov. (collected in dead wood). Polyrhachis sukarmani Kohout, 2007 is recorded for the first time from Thailand. A key to the Thai and Lao species of the subgenus based on the worker caste is given.

A review of Microdytes J. Balfour-Browne, 1946 from Thailand, Laos, and Cambodia with descriptions of five new species and new records (Coleoptera, Dytiscidae).

The diving beetle genus Microdytes J. Balfour-Browne, 1946 in Thailand, Laos, and Cambodia is reviewed, and five new species are described: Microdyteseliasi Wewalka & Okada, sp. nov. (Thailand, Cambodia), M.jeenthongi Okada & Wewalka, sp. nov. (Thailand), M.maximiliani Wewalka & Okada, sp. nov. (Laos, China), M.sekaensis Okada & Wewalka, sp. nov. (Thailand, Laos), M.ubonensis Okada & Wewalka, sp. nov. (Thailand, Laos). Two species are the first country records: M.balkei Wewalka, 1997 (Laos, Cambodia) and M.wewalkai Bian & Ji, 2009 (Laos). For 12 and 8 species, the first provincial records from Thailand and Laos, respectively, are given. A checklist, a key to the 25 known Microdytes species from these countries, and habitus images and illustrations of diagnostic characters are provided. Distribution maps of the recorded species are presented, and species distribution patterns are also briefly discussed.

The Thai species of the Polyrhachis (Myrmatopa) flavicornis Smith, 1857 species group, with description of a new species (Hymenoptera, Formicidae, Formicinae).

The Polyrhachis (Myrmatopa) flavicornis species group in Thailand is reviewed. Four species are recognized, of which one species closely related to Polyrhachis constructor Smith, 1857 is described and illustrated as new to science based on the worker caste under the name Polyrhachis longipilosa sp. nov. The queens of P. flavicornis Smith, 1857 and P. constructor, and the males of P. flavicornis and P. varicolor Viehmeyer, 1916 are described. The new species is distributed in western Thailand in the area north of the Isthmus of Kra, while P. constructor is distributed in Malaysia (West Malaysia and Sabah), Indonesia, Singapore, southern and western Thailand. Polyrhachis piliventris Smith, 1857 and Polyrhachis elii Emery, 1900 are synonymized with P. constructor. A key to the Thai species of the Polyrhachis flavicornis species group is given. The type series of P. longipilosa was collected from the canopy of a dry evergreen forest.

Species Discrimination of Three Odontomachus (Formicidae: Ponerinae) Species in Thailand Using Outline Morphometrics.

All members of the ant genus Odontomachus Latreille, 1804 are venomous ants. Four species in this genus have been identified from Thailand: Odontomachus latidens Mayr, 1867; O. monticola Emery, 1892; O. rixosus Smith, 1757; and O. simillimus Smith, 1758. The three latter species are available and have been used for an outline morphometric study. They display similar morphology, which makes their distinction very difficult except for highly qualified individuals. A total of 80 worker specimens were studied, exploring the contour shapes of their head and pronotum as possible taxonomic characters. The size of each body part was estimated determining the contour perimeter, the values for which were largely overlapping between O. rixosus and O. simillimus; most O. monticola specimens exhibited a significantly larger size. In contrast to the size, each contour shape of the head or pronotum established O. rixosus as the most distinct species. An exploratory data analysis disclosed the higher taxonomic signal of the head contour relative to the pronotum one. The scores obtained for validated reclassification were much better for the head (99%) than for the pronotum (82%). This study supports outline morphometrics of the head as a promising approach to contribute to the morphological identification of ant species, at least for monomorphic workers.

A new species of the ant Platythyreaclypeata species group (Hymenoptera, Formicidae, Ponerinae) from continental Asia.

The Platythyreaclypeata species group is reviewed and three species, including one new species, P.homasawini sp. nov., are recognized. This species group is distinguished from the P.parallela species group by the reddish-brown body, the elliptical shape of the propodeal spiracle, the elongate antennal scape, and the distinctly narrowed posteriad space between frontal carinae. Platythyreahomasawini sp. nov., from Thailand and China, is described based on the worker caste. The type series of the new species was collected on the forest floor from dead wood in an advanced stage of decomposition. A key to the Oriental species of the genus Platythyrea based on the worker caste is provided.

Three new species of the genus Biasticus Stål, 1867 (Insecta, Heteroptera, Reduviidae, Harpactorinae) from Central Highlands, Vietnam.

Three new assassin bug species of the genus Biasticus Stål, 1867 are recognized in Vietnam based on morphological examination, morphometric and molecular phylogenetic analyses, and described as Biasticustaynguyenensis Ha, Truong & Ishikawa, sp. nov., Biasticusgriseocapillus Ha, Truong & Ishikawa, sp. nov., and Biasticusluteicollis Ha, Truong & Ishikawa, sp. nov. The conspecific male and female associations of the new species were confirmed by phylogenetic analyses and DNA barcoding of the mitochondrial 16S rDNA and COI genes. All three new species are presently restricted to the Central Highlands, Vietnam (Kon Chu Rang NR, Gia Lai Province, and Chu Yang Sin NP, Dak Lak Province).

Erratum: Corrigendum: Three new species of the genus Biasticus Stål, 1867 (Insecta, Heteroptera, Reduviidae, Harpactorinae) from Central Highlands, Vietnam. ZooKeys 1118: 133-180. https://doi.org/10.3897/zookeys.1118.83156.

[This corrects the article DOI: 10.3897/zookeys.1118.83156.].

A new species and a new synonym in the scarab genus Parastasia Westwood, 1841 (Coleoptera: Scarabaeidae: Rutelinae), with a key to species from Thailand.

Ten species of the genus Parastasia Westwood, 1841 including a new species and a new record are recorded from Thailand. We here describe Parastasia spinosa Hongsuwong, Sanguansub & Jaitrong, new species from eastern Thailand based on a male specimen. Parastasia bimaculata (Guérin-Méneville, 1843) is recorded for the first time in Thailand. We confirm that Parastasia bigibbosa Nonfried, 1891 occurs in the country. Parastasia andamanae (Ghai, Chandra & Ramamurthy, 1988) is synonymized with P. bigibbosa. A key to the Thai Parastasia species is provided.

An updated checklist of the ants of Thailand (Hymenoptera, Formicidae).

Thailand has a great diversity of ant fauna as a zoogeographical crossroads and biodiversity hotspot. The last publication presenting a Thai ant checklist was published in 2005. In the present paper, based on an examination of museum specimens and published records, a comprehensive and critical species list of Thai ants is synthesized. Currently, 529 valid species and subspecies in 109 genera among ten subfamilies are known from Thailand with their diversity and distribution within 77 provinces presented and assigned to six geographical regions. Furthermore, Thailand is the type locality for 81 ant species. Forty-one species are here newly recorded for Thailand with photographs illustrating these species. The checklist provides information on distribution and a comprehensive bibliography. This study will also serve as a guide for the upper northeast and central Thailand, which are poorly sampled; a comprehensive reference list relating to endemic taxa and localities where conservation is an important priority, thus an essential resource for policy makers and conservation planners concerned with the management of insect diversity in Thailand; and a list of exotic ant species found in Thailand, which could possibly impact the ecological balance.

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).

Two new species of the ant genus Acanthomyrmex Emery, 1893 (Hymenoptera, Formicidae, Myrmicinae) from Thailand.

Acanthomyrmex Emery, 1893 is a small myrmicine genus of the tribe Crematogastrini. Seventeen species of the genus have been recorded from Southeast Asia. Herein, two new species from Thailand (Acanthomyrmexmalikuli sp. n. and Acanthomyrmexmizunoi sp. n.) are added to this genus. Both species belong to Acanthomyrmexluciolae species group. Acanthomyrmexmalikuli was collected from hard dead wood on forest floor, while A.mizunoi nested in soil.

A new species of the ant genus Recurvidris Bolton, 1992 (Hymenoptera, Formicidae, Myrmicinae) from Thailand.

Recurvidris Bolton, 1992 is a small myrmicine genus of the tribe Crematogastrini. Until now, eleven species are known in this genus from Asia. A new species, Recurvidrislekakuli sp. n., is here described from Thailand based on the worker caste. The type series of the new species was collected from leaf litter in a dry evergreen forest. A key to the Asian species of Recurvidris based on the worker caste is provided.

First record of the family Schizodactylidae (Orthoptera: Ensifera) from Thailand, with the description of a new species.

A new species of dune cricket in the family Schizodactylidae, Schizodactylus salweenensis sp. nov. is described from Salween River, Mae Hong Son Province, northwestern Thailand based on both males and females. The Schizodactylidae is recorded for the first time in Thailand. The new species is most similar to Schizodactylus tuberculatus Ander, 1938 and Schizodactylus burmanus Uvarov, 1935 in the morphology of male subgenital plate, but mainly differs in the shape of subgenital plate apex, and the spurs of hind tibiae. The type series was collected from sand dunes along the river. This cricket reaches adulthood during the rainy season.

Two new species of the Aenictus wroughtonii species group (Hymenoptera, Formicidae, Dorylinae) from Thailand.

The Aenictus wroughtonii species group is widely distributed in Asia. The members of this group are characterised by a slender body, long legs, anterior clypeal margin with 5-10 denticles and a weakly-developed subpetiolar process. Twelve worker-based species of this group have been recorded from Asia. Herein, two new species from Thailand (Aenictus nuchitisp. n. and Aenictus samungisp. n.) are added to this group. A key to the Asian species of this group is provided.

Colobopsis explodens sp. n., model species for studies on "exploding ants" (Hymenoptera, Formicidae), with biological notes and first illustrations of males of the Colobopsis cylindrica group.

A taxonomic description of all castes of Colobopsis explodens Laciny & Zettel, sp. n. from Borneo, Thailand, and Malaysia is provided, which serves as a model species for biological studies on "exploding ants" in Southeast Asia. The new species is a member of the Colobopsis cylindrica (COCY) group and falls into a species complex that has been repeatedly summarized under the name Colobopsis saundersi (Emery, 1889) (formerly Camponotus saundersi). The COCY species group is known under its vernacular name "exploding ants" for a unique behaviour: during territorial combat, workers of some species sacrifice themselves by rupturing their gaster and releasing sticky and irritant contents of their hypertrophied mandibular gland reservoirs to kill or repel rivals. This study includes first illustrations and morphometric characterizations of males of the COCY group: Colobopsis explodens Laciny & Zettel, sp. n. and Colobopsis badia (Smith, 1857). Characters of male genitalia and external morphology are compared with other selected taxa of Camponotini. Preliminary notes on the biology of C. explodens Laciny & Zettel, sp. n. are provided. To fix the species identity of the closely related C. badia, a lectotype from Singapore is designated. The following taxonomic changes within the C. saundersi complex are proposed: Colobopsis solenobia (Menozzi, 1926), syn. n. and Colobopsis trieterica (Menozzi, 1926), syn. n. are synonymized with Colobopsis corallina Roger, 1863, a common endemic species of the Philippines. Colobopsis saginata Stitz, 1925, stat. n., hitherto a subspecies of C. badia, is raised to species level.

A sibling species of Platythyrea clypeata Forel, 1911 in southeast Asia (Hymenoptera, Formicidae, Ponerinae).

A new species of the rarely collected ant genus Platythyrea Roger, 1863 closely related to Platythyrea clypeata Forel, 1911 is described and illustrated based on the worker caste under the name Platythyrea janyaisp. n. This species is distributed in southern Thailand and western Malaysia, while P. clypeata is distributed in Sri Lanka, Vietnam, Laos, and Thailand in the areas north of the Isthmus of Kra. Platythyrea clypeata is newly recorded from Thailand from dead wood on the forest floor. The type series of P. janyai was also collected from rotten wood on the forest floor.

The ant genus Rhopalomastix (Hymenoptera: Formicidae: Myrmicinae) in Southeast Asia, with descriptions of four new species from Singapore based on morphology and DNA barcoding.

The true diversity of the Asian ant genus Rhopalomastix Forel is poorly understood. We use an integrated approach to review the known species and subspecies of Rhopalomastix in Southeast Asia. Based on morphology and supporting DNA evidence, we recognize six species. We raise two subspecies of R. rothneyi Forel to species rank (R. johorensis Wheeler stat. n, R. javana Wheeler stat. n.), synonymize R. janeti Donisthorpe (syn. nov.) with R. johorensis, and describe four new species from Singapore: R. glabricephala sp. n., R. murphyi sp. n., R. striata sp. n., and R. tenebra sp. n. All six species found in Southeast Asia are distinct from each other based on morphology; morphological delimitation of these species is further supported by and congruent with mOTUs generated from objective clustering of short fragment COI barcodes using the best close match criteria. Different castes and sexes of most species are described, including redescriptions of the queen of R. javana and male of R. johorensis. A key to the Southeast Asian species based on the worker caste is also provided. Variation among sympatric and also geographically distant populations, and the possibilities of cryptic species, are discussed.

The ant genus Myopias Roger, 1861 (Hymenoptera: Formicidae: Ponerinae) in Thailand, with descriptions of three new species.

The genus Myopias Roger, 1861 is distributed in the Australian, Oceanian, Oriental and southern Sino-Japanese realms. Currently 40 valid species and three subspecies have been described, but none have ever been recorded for Thailand. Here we review the species of Thailand, recognizing seven in total. Four are new records of previously described species: Myopias bidens (Emery, 1900), M. crawleyi (Donisthorpe, 1941), M. maligna punctigera (Emery, 1900), and M. mandibularis (Crawley, 1924). Three new species are described: Myopias minima sp. nov. from southern Thailand, M. sakaeratensis sp. nov. from eastern Thailand and M. sonthichaiae sp. nov. from northern and western Thailand. The queen caste of M. mandibularis is described here for the first time and additional descriptions of other species are provided. All these species were found to nest in rotten wood on the forest floor.