Darwin wasps of Mexico (Hymenoptera: Ichneumonidae): the subfamilies Acaenitinae, Poemeniinae and Xoridinae

Mexican species of the ichneumonid subfamilies Acaenitinae, Poemeniinae and Xoridinae are reviewed. The following genera are recorded here from Mexico: Arotes Gravenhorst, 1829 (one species) and Coleocentrus Gravenhorst, 1829 (one species) in Acaenitinae; Ganodes Townes, 1957 (one species), Podoschistus Townes, 1957 (one species), Poemenia Holmgren, 1859 (one species) and Rodrigama Gauld, 1991 (one species) in Poemeniinae; and Aplomerus Provancher, 1886 (one species), Odontocolon Cushman, 1942 (one species) and Xorides Latreille, 1809 (five species) in Xoridinae. One species, Coleocentrus clebschi Khalaim, sp. nov., is described as a new to science. The tribes Coleocentrini and Rodrigamini, the genera Coleocentrus, Podoschistus, Poemenia and Rodrigama, and the species Podoschistus vittifrons (Cresson, 1968), Rodrigama gamezi Gauld, 1991 and Aplomerus buprestivorus Rohwer, 1920 are recorded from Mexico for the first time. The taxonomic status of Ganodes mexicanus Díaz, 2008 is discussed.

New geographical records of Mesembrinellidae (Diptera: Oestroidea) in Mexico

Currently, the family Mesembrinellidae has 55 extant species restricted to the Americas. In this study, the distribution of 6 out of 55 species which corresponds to the Mexican species of the family is discussed. New geographical records are presented for Laneella fuscosquamata Whitworth, 2019, Mesembrinella bicolor (Fabricius, 1805), and Mesembrinella socors (Walker, 1861). Furthermore, a complete list of synonyms is provided for each species.

Darwin wasps of the subfamily Pimplinae (Hymenoptera: Ichneumonidae) of Mexico: genera Apechthis Förster, Itoplectis Förster and Pimpla Fabricius

Mexican species of three pimpline genera, Apechthis Förster (one species), Itoplectis Förster (six species) and Pimpla Fabricius (20 species, including one unidentified taxon), are reviewed. Four species of Pimpla are described as new to science: P. chamela sp. nov., P. oaxacana sp. nov., P. tequila sp. nov. and P. xalapana sp. nov. Pimpla thoracica Morley, 1914 is found to be a junior synonym of P. ellopiae Harrington, 1892 (syn. nov.). Apechthis zapoteca (Cresson) is recorded for the first time from Venezuela, Pimpla dimidiata (Townes) from Mexico, P. caeruleata Cresson, P. croceiventris (Cresson), P. sanguinipes Cresson and P. sumichrasti Cresson from Honduras, P. ichneumoniformis Cresson and P. viridescens Morley from Guatemala and Honduras, and P. punicipes Cresson from Panama. The South American species Pimpla caerulea Brullé and the Nearctic species P. pedalis Cresson are excluded from the Mexican fauna. Male of Itoplectis mexicana and female of Pimpla dimidiata are recorded for the first time. Identification keys to the species of Itoplectis and Pimpla occurring in Mexico are provided.

Two new species of snail-eating snakes of the genus Tropidodipsas (Serpentes, Dipsadidae) from southern Mexico, with notes on related species

We describe two new species of Tropidodipsas related to the T. fasciata species group as defined by Kofron (1987), and provide morphological and molecular data to support the novelty of both species. A partial molecular phylogeny of the Mexican species of snail-eating snakes (Serpentes, Dipsadidae) is presented, and we discuss evolutionary relationships as supported by our molecular results. We analyze specific relationships of the new species described herein with their closest relatives. We present a distribution map for all species of Tropidodipsas and include photographs of living individuals of each species. Finally, we discuss other taxonomic changes based on our molecular phylogeny as well as conservation priorities of the new species.

Redescription of Rhysodesmus dasypus (Gervais, 1847), the type species of the genus (Polydesmida: Xystodesmidae)

As both the type of the genus and the largest known xystodesmid, Rhysodesmus dasypus (Gervais, 1847) is an important and charismatic Mexican species. Despite there are numerous taxonomic contributions, R. dasypus remains enigmatic and poorly diagnosed, necessitating the need for an updated taxonomic synthesis. Here, we present a redescription of R. dasypus based on eight specimens collected from three localities in close proximity to the suggested type locality of the species and include photographs of the diagnostic morphological characters. Additionally, we include a distribution map of previously reported localities from the literature and two new localities.

Nectar secretion in a dry habitat: structure of the nectary in two endangered Mexican species of Barkeria (Orchidaceae)

Barkeria scandens and B. whartoniana are endangered, endemic taxa from Mexico. They are epiphytes adapted to dry habitats. Since these plants are xerophytic, their flowers were investigated for structural adaptations to nectar secretion. The flowers of both species are structurally similar, and contrary to most claims for the genus, have functional floral nectaries comprising a nectary chamber and a narrow tubular cuniculus. Nectar is present in both these structures, and contains sugars and lipid-like compounds. The nectary tissue is composed of a single-layered epidermis overlying 1–2 layers of subepidermal secretory parenchyma. The outer tangential wall of the epidermal cells is thick and multi-layered, whereas the cuticle, which often shows blistering, is lamellate and possesses micro-channels. Lipid-like material occurs both between the microfibrils of the cell wall and in the micro-channels. Robust secretory tissue, thick cell walls, and lipid-like nectar components limit nectar evaporation. Moreover, the rigidity of the nectary potentially makes it possible for red-flowered B. scandens to switch from entomophily to ornithophily.

A new species of Ambrysus Stål from the Central Mexican Plateau and new state records for species of the genus in the country (Heteroptera: Nepomorpha: Naucoridae)

The genus Ambrysus Stål is a species-rich genus in which multiple species groups have been proposed, including the North American Ambrysus signoreti Stål complex. The new Mexican species Ambrysus altiplanus Reynoso n. sp., which belongs to the A. signoreti complex, is described and illustrated, bringing the total number of described species of Ambrysus to 67. Also, new state records are reported for three species of the same complex, two of which are endemic to Mexico.