The hog-badger is not an edentate: systematics and evolution of the genus Arctonyx (Mammalia: Mustelidae)

Cathemerality: a key temporal niche

Given the marked variation in abiotic and biotic conditions between day and night, many species specialise their physical activity to being diurnal or nocturnal, and it was long thought that these strategies were commonly fairly fixed and invariant. The term 'cathemeral', was coined in 1987, when Tattersall noted activity in a Madagascan primate during the hours of both daylight and darkness. Initially thought to be rare, cathemerality is now known to be a quite widespread form of time partitioning amongst arthropods, fish, birds, and mammals. Herein we provide a synthesis of present understanding of cathemeral behaviour, arguing that it should routinely be included alongside diurnal and nocturnal strategies in schemes that distinguish and categorise species across taxa according to temporal niche. This synthesis is particularly timely because (i) the study of animal activity patterns is being revolutionised by new and improved technologies; (ii) it is becoming apparent that cathemerality covers a diverse range of obligate to facultative forms, each with their own common sets of functional traits, geographic ranges and evolutionary history; (iii) daytime and nighttime activity likely plays an important but currently neglected role in temporal niche partitioning and ecosystem functioning; and (iv) cathemerality may have an important role in the ability of species to adapt to human-mediated pressures.

Morphology and genetic characterization of Physaloptera sibirica Petrow & Gorbunov, 1931 (Spirurida: Physalopteridae), from the hog-badger Arctonyx collaris Cuvier (Carnivora: Mustelidae), with molecular phylogeny of Physalopteridae

BACKGROUND

Nematodes of the family Physalopteridae (Spirurida: Physalopteroidea) commonly parasitize the alimentary canal of all major vertebrate groups. However, many physalopterid species are not adequately described, especially regarding the detailed morphology of the cephalic end. The current genetic database for Physaloptera species is still very limited, which seriously hampers molecular-based species identification. Additionally, the systematic status of some genera and the evolutionary relationships of the subfamilies in the Physalopteridae remain under debate.

METHODS

New morphological data for Physaloptera sibirica was gathered using light and scanning electron microscopy based on newly collected specimens from the hog badger Arctonyx collaris Cuvier (Carnivora: Mustelidae) in China. Six different genetic markers, including nuclear small ribosomal DNA (18S), large ribosomal DNA (28S) and internal transcribed spacer (ITS), mitochondrial cytochrome c oxidase subunit 1 (cox1) and subunit 2 (cox2), and the 12S small subunit ribosomal RNA gene of P. sibirica were sequenced and analyzed for the first time to our knowledge. Additionally, to construct a basic molecular phylogenetic framework for the Physalopteridae, phylogenetic analyses were performed based on the cox1 and 18S + cox1 genes using maximum likelihood (ML) and Bayesian inference (BI) methods.

RESULTS

Scanning electron microscopy (SEM) observation displayed the details of the cephalic structures, deirids, excretory pore, caudal papillae, vulva, phasmids and egg of P. sibirica for the first time to our knowledge. Pairwise comparison of the sequences obtained for P. sibirica did not reveal intraspecific divergence regarding the 18S, 28S, cox1 and 12S genetic markers and a low level of divergence in the ITS (0.16%) and cox2 (2.39%) regions. Maximum likelihood and Bayesian inference analyses showed that the representatives of Physalopteridae formed two major clades (species of Physalopterinae + Thubunaeinae parasitic in terrestrial vertebrates and Proleptinae only occurring in marine or freshwater fishes). Turgida turgida was found nested among representatives of Physaloptera. Physaloptera sibirica clustered together with P. rara. Physalopteroides sp. (Thubunaeinae) formed a sister relationship to the physalopterine Abbreviata caucasica.

CONCLUSIONS

Physaloptera sibirica was redescribed, which is the fourth nematode parasite reported from the hog badger A. collaris, and A. collaris represents a new host for P. sibirica. The phylogenetic results challenged the validity of the subfamily Thubunaeinae and of the genus Turgida and supported dividing the family Physalopteridae into two subfamilies, Physalopterinae and Proleptinae. However, we do not make any immediate systematic changes in the Physalopteridae, because a more rigorous study with broader representation of the Physalopteridae is required. These present findings contribute to morphologically identifying P. sibirica more accurately and provide new insights into the systematics of the Physalopteridae.

How far westward? Revisiting the distribution of Arctonyx badgers in the westernmost global range

Bangladesh delimits the westernmost range of Arctonyx badgers, but their presence in the country is not completely understood. The whole of Bangladesh is reportedly home to the northern hog badger (A. albogularis); however, there is no valid record to date. The greater hog badger (Arctonyx collaris), its larger congener and a globally vulnerable mustelid, has three valid records. This work, between 2001 and 2021, traced 28 records (all of A. collaris: 20 from literature review and social media, 8 from camera-trapping) in Bangladesh including four rare cases of erythrism and seven conflict incidents. All but five were from mixed evergreen forests of southeast Bangladesh, the known A. collaris range. One record was from wet deciduous forests of northern Bangladesh (bordering Meghalaya, India), a region not previously marked as an A. collaris range. In 2021, from 4436 trap-nights of sampling, 17 notionally-independent events (all night-time) were obtained. This produced the first evidence of A. collaris in northeast Bangladesh, a region that borders the Tripura Hills, India (where it was first recorded in 2020) and belongs to the Indo-Burma biodiversity hotspot. The work proves the existence of relict populations whereas the absence of A. albogularis signifies a re-assessment of its westernmost distribution.

Greater Hog Badger Arctonyx collaris (Mustelidae, Carnivora) from the Pleistocene of Vietnam (Lang Trang Cave)

The dental remains of a large badger collected in 2020 from the Pleistocene deposits of the Lang Trang karstic cave in northern Vietnam are described. The molars М¹ and М₁ exhibit the features that are characteristic of Arctonyx collaris Cuvier, 1825. At the same time, the length of M₁ of the Lang Trang form exceeds that of modern greater hog badgers. Based on the size and structure of the teeth, it can be assigned to the subspecies A. c. rostratus Matthew et Granger, 1923 known from the Pleistocene of China and Southeast Asia.

JM, Rutter AR, Hawkins MTR, Garcia FJ, Helgen KM. The Taxonomic Status of Mazama bricenii and the Significance of the Táchira Depression for Mammalian Endemism in the Cordillera de Mérida, Venezuela

We studied the taxonomy and biogeography of Mazama bricenii, a brocket deer classified as Vulnerable by the IUCN, drawing on qualitative and quantitative morphology and sequences of the mitochondrial cytochrome-b gene. We used Ecological Niche Modeling (ENM) to evaluate the hypothesis that M. bricenii of the Venezuelan Cordillera de Mérida (CM) might have become isolated from populations of its putative sister species, Mazama rufina, in the Colombian Cordillera Oriental (CO). This hypothesis assumes that warm, dry climatic conditions in the Táchira Depression were unsuitable for the species. Our analyses did not reveal morphological differences between specimens geographically attributable to M. bricenii and M. rufina, and phylogenetic analyses of molecular data recovered M. bricenii nested within the diversity of M. rufina. These results indicate that M. bricenii should be regarded as a junior synonym of M. rufina. ENM analyses revealed the existence of suitable climatic conditions for M. rufina in the Táchira Depression during the last glacial maximum and even at present, suggesting that gene flow between populations in the CO and CM may have occurred until at least the beginning of the current interglacial period and may continue today. Because this pattern might characterize other mammals currently considered endemic to the CM, we examined which of these species match two criteria that we propose herein to estimate if they can be regarded as endemic to the CM with confidence: (1) that morphological or molecular evidence exists indicating that the putative endemic taxon is distinctive from congeneric populations in the CO; and (2) that the putative endemic taxon is restricted to either cloud forest or páramo, or both. Only Aepeomys reigi, Cryptotis meridensis, and Nasuella meridensis matched both criteria; hence, additional research is necessary to assess the true taxonomic status and distribution of the remaining species thought to be CM endemics.

Taxonomic revision of the olingos (Bassaricyon), with description of a new species, the Olinguito

We present the first comprehensive taxonomic revision and review the biology of the olingos, the endemic Neotropical procyonid genus Bassaricyon, based on most specimens available in museums, and with data derived from anatomy, morphometrics, mitochondrial and nuclear DNA, field observations, and geographic range modeling. Species of Bassaricyon are primarily forest-living, arboreal, nocturnal, frugivorous, and solitary, and have one young at a time. We demonstrate that four olingo species can be recognized, including a Central American species (Bassaricyon gabbii), lowland species with eastern, cis-Andean (Bassaricyon alleni) and western, trans-Andean (Bassaricyon medius) distributions, and a species endemic to cloud forests in the Andes. The oldest evolutionary divergence in the genus is between this last species, endemic to the Andes of Colombia and Ecuador, and all other species, which occur in lower elevation habitats. Surprisingly, this Andean endemic species, which we call the Olinguito, has never been previously described; it represents a new species in the order Carnivora and is the smallest living member of the family Procyonidae. We report on the biology of this new species based on information from museum specimens, niche modeling, and fieldwork in western Ecuador, and describe four Olinguito subspecies based on morphological distinctions across different regions of the Northern Andes.

Under pressure? Dental adaptations to termitophagy and vermivory among mammals

The extant mammals have evolved highly diversified diets associated with many specialized morphologies. Two rare diets, termitophagy and vermivory, are characterized by unusual morphological and dental adaptations that have evolved independently in several clades. Termitophagy is known to be associated with increases in tooth number, crown simplification, enamel loss, and the appearance of intermolar diastemata. We observed similar modifications at the species level in vermivorous clades, although interestingly the vermivorous mammals lack secondarily derived tools that compensate for the dentition's reduced function. We argue that the parallel dental changes in these specialists are the result of relaxed selection on occlusal functions of the dentition, which allow a parallel cascade of changes to occur independently in each clade. Comparison of the phenotypes of Rhynchomys, a vermivorous rat, and strains of mice whose ectodysplasin (EDA) pathway has been mutated revealed several shared dental features. Our results point to the likely involvement of this genetic pathway in the rapid, parallel morphological specializations in termitophagous and vermivorous species. We show that diets or feeding mechanisms in other mammals that are linked to decreased reliance on complex can lead to similar cascades of change.