The Australambrysus plax (La Rivers, 1967) species complex (Heteroptera: Naucoridae), with descriptions of three new species.

The taxonomy of the neotropical saucer bug genus Australambrysus Reynoso & Sites, 2021 is poorly understood. Although 24 species have been described, the genus is in need of revision and many new species await description. A clade of species of Australambrysus exhibits a similar appression of the propleura to the prosternum as do species of the North American Ambrysus Stål, 1862 subgenus Syncollus La Rivers, 1965. Three new species in this clade are described here: Australambrysus aguaro n.sp., A. alvarado n.sp., and A. clavieri n.sp. In addition, Australambrysus planus plax (La Rivers, 1967) is elevated to species level, and thus becomes A. plax n.stat.

Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 2.

The Ambrysus signoreti Stål species complex was recently diagnosed and subdivided into three sections based on morphology of the female subgenital plate. In the present study, the species in the second section, characterized by the posterior margin of the subgenital plate with central lobe extending posteriorly further than the posterolateral corners, are revised. Supplemental descriptions for four species described by La Rivers and Usinger are provided. The group includes six species: four from Mexico (Ambrysus brailovskyi Reynoso & Sites, A. henryi Reynoso & Sites, A. inflatus La Rivers, A. lundbladi Usinger), one from Mexico and the United States (A. lunatus Usinger), and one from Costa Rica (A. harmodius La Rivers). Also, the subspecies A. lunatus menoides La Rivers is proposed as a junior synonym of A. lundbladi. We herein report for the first time characteristics of the previously unknown male of A. lundbladi. Additionally, we present new state records from Mexico for A. inflatus and A. lundbladi, and new province records from Costa Rica for A. harmodius. Finally, an illustrated key to the species in the second section of the complex is provided.

Revision of Limnocoris Stål (Heteroptera: Nepomorpha: Naucoridae) of the Guiana Shield and Amazon regions.

The species of Limnocoris of the Guiana Shield and Amazon regions of South America are revised, including the descriptions of five new species: L. amazonensis n. sp., L. moreirai n. sp., and L. yanomami n. sp. from Brazil, L. flavescens n. sp. from Venezuela, and L. inflatus n. sp. from Suriname. Further, supplemental descriptions are provided for four previously described species: L. burmeisteri De Carlo, L. fittkaui De Carlo, L. menkei La Rivers, and L. surinamensis Nieser n. stat.; the latter was a subspecies and is here elevated to full species status. The following synonymies are proposed, with junior synonyms in brackets: L. burmeisteri De Carlo [L. lautereri Nieser, Chen & Melo n. syn.] and L. menkei La Rivers [L. birabeni De Carlo n. syn., L. bruchi De Carlo n. syn.]. An illustrated taxonomic key and distribution maps are also presented.

Nomenclatural updates to the taxonomy of Naucoridae (Hemiptera: Heteroptera).

N/A.

Notes on the morphology of two species of Limnocoris Stål (Heteroptera: Naucoridae) from South America.

In the present study, new distribution records and notes on the wing polymorphism of Limnocoris pallescens (Stål, 1861), a species distributed in Colombia and Venezuela, are presented. Also, after the discovery of two female paralectotypes of L. pectoralis Montandon, 1897 deposited at the Natural History Museum in London, ongoing uncertainty about the shape of the diagnostic mediosternite VII (subgenital plate) of this species has been resolved.

A new species of Maculambrysus Reynoso & Sites, 2021 (Hemiptera: Heteroptera: Naucoridae) from an aguaje palm swamp in southeastern Peru.

The neotropical saucer bug genus Maculambrysus Reynoso & Sites is currently represented by five species from Tabasco, Mxico to Par, Brazil. Presented here is the description of a sixth species, Maculambrysus gallicei n.sp., which was collected from rootmats and leafpacks in an aguaje palm swamp in southeastern Peru. It can be distinguished from most congeners by the concolorous dark-brown hemelytra and the mottled orange-brown pronotum, as well as characteristics of the male accessory genitalic process of tergum VI, and female subgenital plate and laterosternites VI. Other aquatic Heteroptera co-occurring with this new species are given.

The Naucoridae (Heteroptera: Nepomorpha) of Madagascar, with revisions of Temnocoris and Tsingala (Laccocorinae).

The island nation of Madagascar was surveyed extensively through a series of expeditions to determine the fauna of Naucoridae. Previously, 17 species in four genera had been reported from the country. All taxa previously recorded from Madagascar were re-collected, with the exception of three species, Macrocoris flavicollis Signoret, Temnocoris starmuhlneri Poisson, and Tsingala nossibeanus (Bergroth). Macrocoris flavicollis is removed from the list of species occurring in Madagascar. Within Laccocorini (Laccocorinae), a new genus, Gonioathrix n.gen. is described; Temnocoris and Tsingala are revised; three new species are described in Temnocoris (T. leachi n.sp., T. montandoni n.sp., T. poissoni n.sp.) and four in Tsingala (T. angulata n.sp., T. latiforma n.sp., T. spatulata n.sp., T. trilobata n.sp.). Lectotypes are designated for Afronaucoris madagascariensis (Montandon), Tsingala humeralis (Signoret), and T. naucoroides (Montandon). In Macrocorinae, a new species of Macrocoris, M. namorona n.sp., from Ranomafana National Park is described. These taxonomic actions bring the total for the country to five genera and 25 species. Distributions, habitat associations, and a key to the species are presented.

Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 1.

The species-rich Ambrysus signoreti Stål species complex is diagnosed and subdivided into three sections based on morphology of the female subgenital plate. The species in the first section, characterized by the posterior margin of the subgenital plate with posterolateral corners extending posteriorly further than the central lobe, are revised. The group includes four species: two previously described from Mexico (Ambrysus cosmius La Rivers, A. schuhi Reynoso & Sites), one from Costa Rica (A. variegatus Usinger), and a new species, A. morelosensis n. sp., from central Mexico. The description of the new species and transfer of A. mormon Montandon to the A. guttatipennis Stål species complex brings the total number of species in the complex to 24 and the total number of described species of Ambrysus to 68. Also, an illustrated key to the species in this first section of the complex is provided. Finally, we present new state records from Mexico for A. cosmius and new province records from Costa Rica for A. variegatus.

The Gyrinidae (Coleoptera) fauna of Thailand: Key to tribes and genera, with new records and keys to species of Dineutini and Gyrinini.

Eighteen species and four genera of the family Gyrinidae are recorded from Thailand. Seven species, belonging to three genera in the tribes Dineutini and Gyrinini, are here treated in detail. Dineutus sitesi Gustafson, Hjek Miller, D. spinosus (Fabricius), D. unidentatus Aub, Porrorhynchus marginatus Laporte and Gyrinus sericeolimbatus Rgimbart were already known, whereas D. australis (Fabricius) and Gyrinus smaragdinus Rgimbart are recorded for the first time. Diagnoses, distribution maps and keys to tribes, genera, and all species of Dineutus and Gyrinus occurring in Thailand are provided. The fourth genus, Patrus (tribe Orectochilini), has been partly revised in a preceding paper.

Revision of Limnocoris Stål (Heteroptera: Nepomorpha: Naucoridae) of the tropical Andes.

The species of Limnocoris of the tropical Andes of South America are revised, including the descriptions of eight new species: L. chrysosetosus n. sp. from Ecuador; L. elongatus n. sp. and L. emboliatus n. sp. from Colombia; L. molanoi n. sp. from Colombia and Ecuador; L. luisae n. sp. from Colombia and Venezuela; L. longirostris n. sp. from Venezuela; L. nieseri n. sp. from Colombia, Ecuador, and Panama; and L. reynosoi n. sp. from Brazil, Colombia, and Venezuela. Further, supplemental descriptions are provided for the previously described species. The following taxa are resurrected from synonymy and their species status are restored: Limnocoris peruvianus Melin stat. restit. from synonymy with L. pectoralis Montandon, and L. stali Montandon stat. restit. from synonymy with L. borellii Montandon. The following synonymies are proposed, with junior synonyms in brackets: L. borellii Montandon [L. horvathi Montandon n. syn.], L. dubiosus Montandon [L. aymarana Poisson n. syn.], L. malkini La Rivers [L. pulchellus n. syn.], L. obscurus Montandon [L. trilobatus Nieser, González, Eichelkraut, n. syn.], L. ochraceus Montandon [L. maculatus De Carlo n. syn.], L. pallescens (Stål) [L. bergrothi Montandon n. syn.], L. pectoralis Montandon [L. rivalis Melin n. syn.], L. peruvianus Melin [L. calii Nieser, González Eichelkraut n. syn.] and L. stali Montandon [L. robustus Roback Nieser n. syn., L. carcharus La Rivers n. syn.]. Lectotypes are designated for five species: L. aymarana, L. bergrothi, L. borellii, L. dubiosus, and L. stali. An illustrated taxonomic key and distribution maps also are presented.

Review of the Patrus landaisi species group from Thailand with description of three new species (Coleoptera, Gyrinidae).

A survey of the whirligig beetles of the genus Patrus Aubé, 1838 occurring in Thailand belonging to the newly designated Patrus landaisi species group is presented. Three new species are described and illustrated: P. garuda sp. nov., P. nanensis sp. nov. and P. phetchabunensis sp. nov.; with P. apicalis (Régimbart, 1891), P. landaisi (Régimbart, 1892), and P. subapicalis (Ochs, 1930) stat. nov. being recorded for the first time in Thailand. Morphological and molecular analyses, together in an integrative approach, support the elevation of P. subapicalis to species status, instead of being a subspecies of P. apicalis. A diagnosis, illustrations of habitus and diagnostic characters, distribution maps, habitat images and a key to species are provided for all known members of the P. landaisi species group that occur in Thailand. A checklist of species in the group is also given.

A review of emCryphocricos/em Signoret, 1850 (Naucoridae: Cryphocricinae) with descriptions of three new species.

The genus Cryphocricos Signoret, 1850 was recently determined in a molecular phylogeny to be distantly related to other taxa of the subfamily Cryphocricinae to the extent that it is now once again the sole member of the subfamily. This exclusively New World group of aquatic bugs lives in fast and usually turbulent current and respires by means of a plastron. Efforts to identify morphological features to distinguish among the species have largely fallen short, and some species have been established based on features that exhibit a high degree of intraspecific variation overlapping those of other species. Presented here is a review of the 13 described species with discussions of their features and photos of type specimens, and three new species from Venezuela and Colombia are described. Also presented is a diagnostic attribute unique to the enigmatic Cryphocricos barozzii Signoret, 1850.

The Pleidae (Hemiptera, Heteroptera) of Thailand, with the descriptions of two new species and a discussion of species from Southeast Asia.

The family Pleidae is represented in Thailand by four species in the genus Paraplea. Two of these species, P. frontalis and P. liturata, are widespread and relatively common in Southeast Asia. Two other species, P. lateromaculata Cook, sp. nov. and P. melanodera Cook, sp. nov., are described and only known from Thailand. Full descriptions are provided for all four species. The distributions of these species are discussed, with an emphasis on Thailand. Paraplea frontalis, P. liturata, and P. lateromaculata Cook, sp. nov. are relatively widespread within Thailand and have overlapping distributions whereas P. melanodera Cook, sp. nov. appears restricted to small brackish ponds near western coastal areas of peninsular Thailand.

Revision of the American genus Steinovelia Polhemus amp; Polhemus, 1993 (Heteroptera: Gerromorpha: Veliidae).

The genus Steinovelia Polhemus Polhemus, 1993 is distributed from southeastern Canada to northeastern Argentina and has been considered to contain five valid species: S. permista (Drake, 1951a), S. placida (Drake, 1951a), S. stagnalis (Burmeister, 1835), S. vinnula (Drake, 1951b) and S. virgata (White, 1879a). We present here a revision of the genus with redescriptions of S. permista, S. stagnalis, S. vinnula, and S. virgata, the synonymy of S. placida with S. virgata, a key, distribution maps, and photographs of all species.

Descriptions of four new species of the Ambrysus signoreti Stål species complex (Heteroptera: Nepomorpha: Naucoridae.

The genus Ambrysus Stål is the most species rich genus of Naucoridae. Multiple species groups in the genus have been proposed, including the North American Ambrysus signoreti Stål complex. Four new species belonging to the A. signoreti complex are described and illustrated: three from Mexico (Ambrysus brailovskyi Reynoso Sites n. sp., A. henryi Reynoso Sites n. sp., A. schuhi Reynoso Sites n. sp.) and one from Mexico and Guatemala (A. sitesi Reynoso n. sp.), bringing the total number of described species of Ambrysus to 97.

The probable larva of Anotogaster gregoryi Fraser, 1923, with new distributional records of the genus from northern Thailand (Odonata: Cordulegastridae).

The probable larva of Anotogaster gregoryi Fraser, 1923 is described for the first time by supposition based upon four F-0 larvae collected in the provinces of Loei and Phitsanulok, which are new province records for Anotogaster in Thailand.

Revision of Limnocoris (Heteroptera: Nepomorpha: Naucoridae) of North America.

The North American species of Limnocoris are revised and total 13 species after the present study. Four new species are described and illustrated: L. chaetocarinatus n. sp. from Costa Rica, Panama, and Colombia; L. major n. sp. and L. nanus n. sp. from Costa Rica and Panama; and L. zacki n. sp. from Mexico and Guatemala. Further, supplemental descriptions are provided for the previously described species. The following synonymies are proposed, with junior synonyms in brackets: L. insularis Champion [L. alcorni La Rivers n. syn.], L. pygmaeus La Rivers [L. solenoides La Rivers n. syn.], and L. signoreti Montandon [L. brailovskyi La Rivers n. syn., L. laucki La Rivers n. syn., L. stangei La Rivers n. syn.]. A lectotype is designated for L. signoreti. Limnocoris profundus (Say) is considered a nomen dubium because no type specimens have been found and the original description is insufficient to establish its identity. An illustrated taxonomic key, distribution maps, and a discussion of the characters (putative synapomorphies) not previously mentioned in the literature also are presented.

The larva of Amphigomphus somnuki Hämäläinen, 1996 and the first records of the genus Stylogomphus Fraser, 1922 for Thailand (Odonata: Gomphidae).

The larva of Amphigomphus somnuki Hämäläinen, 1996 is described for the first time based on an emerged male specimen from Chiang Mai Province, and several F-0 larvae collected in other provinces of Thailand. The larva of A. somnuki is the smallest and differs from A. nakamurai Karube, 2001 by the caudal appendages densely covered with minute spiniform setae, and from A. hansoni Chao, 1954 by the male epiproct with the dorsal tubercles at 0.65 the length of the epiproct. New province records for A. somnuki and the first records of Stylogomphus Fraser, 1922 for Thailand are provided.

The larvae of Phaenandrogomphus Lieftinck, 1964 in Thailand, including the description of P. tonkinicus (Fraser, 1926) with a larval diagnosis and new province records of P. asthenes Lieftinck, 1964 (Odonata: Gomphidae).

The larva of Phaenandrogomphus tonkinicus (Fraser, 1926) is described for the first time based on several F-0 larvae collected in Chiang Mai and Nan provinces of Thailand. The larva of P. tonkinicus differs from that of P. asthenes Lieftinck, 1964 by having the 3rd antennomere mesal margin strongly convex, 4th antennomere vestigial and dome-like, postclypeus thick and shelf-like, S8 lacking a posterolateral spine, and cerci usually shorter than the epiproct. New Thailand province records of P. asthenes also are provided.

Revision of the Ambrysus pudicus Stål species complex (Heteroptera: Nepomorpha: Naucoridae) with the description of a new species from southern Mexico.

The Ambrysus pudicus Stål species complex is revised, its species diagnosed, and an illustrated key is presented. The complex includes A. abortus La Rivers, A. amargosus La Rivers, A. funebris La Rivers, A. hungerfordi Usinger, A. parviceps Montandon, A. pudicus Stål, and A. relictus Polhemus Polhemus. A new species, A. chinanteco, belonging to this complex is described from southern Mexico. The subspecies A. hungerfordi angularis La Rivers, A. h. spicatus La Rivers, and A. h. triunfo La Rivers are herein elevated to full species level and considered members of this species complex. The subspecies A. pudicus barberi Usinger is synonymized with the nominate subspecies. Based on specific combinations of morphological features, two subcomplexes of species are recognized within the complex. The species A. funebris is transferred from the subgenus Acyttarus La Rivers to the subgenus Ambrysus Stål. In order to fix the identity of three species in the complex, neotypes for A. amargosus and A. spicatus and a lectotype for A. pudicus are designated here. The species in the A. pudicus complex are distributed in North America from the southwestern and southern United States to northern Costa Rica. New country records from Central America are presented for A. parviceps and A. pudicus. New state records from Mexico are presented for A. abortus, A. angularis, A. hungerfordi, A. parviceps, A. pudicus, and A. spicatus.