Diagnostic notes on the spider orb-weaving genera Carepalxis and Ocrepeira (Araneae: Araneidae), with description of three new species from Central Brazil

Three new species of the araneid spider genera Carepalxis L. Koch, 1872 and Ocrepeira Marx, 1883 from Central Brazil are described and illustrated: Carepalxis topazio new species, based on a single female from Cristalina; C. quasimodo new species, from Brasília and Jaborandi based on females and a male, this being the first male of Carepalxis described in the American continent; and Ocrepeira planalto new species, based on males and females from Cavalcante, Cristalina, Jaborandi and Alto Paraíso. A key to Carepalxis females in the New World is provided. Furthermore, the similarity between American Carepalxis and Ocrepeira is discussed, with diagnostic considerations.

Molecular analysis reveals Latonius planus Kononova to be a derived species of Trissolcus Ashmead

The monotypic genus Latonius Kononova, 1982 (Platygastroidea, Scelionidae), was described from a single female specimen collected in southern Ukraine. It somewhat resembles Trissolcus Ashmead but has a distinctive claval formula. The only species in the genus, Latonius planus Kononova, 1982, is lacking any details regarding biology, sexual dimorphism, intraspecific variability, or distribution. Based on recently collected specimens the present study clarifies the position of Latonius within the Telenominae, provides a comprehensive description accompanied by high quality images, and compares Latonius and Trissolcus. Five molecular markers were amplified, and sequences of L. planus were analyzed using a data set for the molecular phylogeny of Telenominae (Taekul et al. 2014) and a molecular phylogeny of Trissolcus (Talamas et al. 2019). We dissected the metasoma, tarsi, antennae, and ovipositor and performed SEM imaging. The genera Latonius and Ioseppinella Mineo, O’Connor & Ashe, 2010, are treated as junior synonyms of Trissolcus and the type species of Latonius and Ioseppinella are considered to be conspecific (syn. nov.).

Distributional range expansion of the parasitic wasp Lirata batesella (Westwood, 1874) (Hymenoptera, Eucharitidae)

This study is focused on the expansion of the distributional range of Lirata batesella (Westwood, 1874) (Hymenoptera, Eucharitidae) and based on a single female specimen deposited at Coleção Entomológica do Laboratório de Sistemática e Bioecologia de Predadores e Parasitoides of the Instituto Biológico, in Ribeirão Preto, São Paulo state, Brazil. Santarém, in Pará state, Brazil, the type locality, is the only known distribution record for the species. Here, we provide a new distribution record for L. batesella, in Luiz Antônio, São Paulo state, about 2,200 km south of the type locality, which represents a significant increase in its distribution range. A map showing the geographical distribution of L. batesella based on the new record and literature is provided.

Contributions to the knowledge of Neotropical Castianeirinae (Araneae: Corinnidae): redescription of Castianeira spinipalpis Mello-Leitão, 1945, with first description of the male, and description of a new Myrmecotypus O. Pickard-Cambridge, 1894 from the Bolivian Moxos plains

Two Neotropical species of the subfamily Castianeirinae are treated herein. Castianeira spinipalpis Mello-Leitão, 1945 was described from a single female specimen; we provide a redescription of the female and the male is described for the first time. The species is newly recorded from Paraguay and Bolivia. Also, Myrmecotypus rubioi sp. nov. is described from the Bolivian Moxos plains, a tropical savanna ecoregion of the Beni department of northern Bolivia. The new species can be distinguished from others in the genus by having tibia I spination 3-2, coxa II whitish (the remainder dark), and a unique male palpal embolus with two broad embolic discs basal to the embolus tip.

Felicitous Underspecification

Felicitous uses of contextually sensitive expressions generally have unique semantic values in context. For example, a felicitous use of the singular pronoun ‘she’ generally has a single female as its unique semantic value in context. In the present work, it is argued that contextually sensitive expressions have felicitous uses where they lack unique semantic values in context. The author calls such uses instances of felicitous underspecification. In these uses, the underspecified expression is associated with a range of candidate semantic values in context. A rule is provided for updating the Stalnakerian common ground when sentences containing felicitous underspecified expressions are uttered and accepted in a conversation. The author also gives an account of the mechanism that associates the range of candidate semantic values in context with an underspecified expression. Sentences containing felicitous underspecified expressions can be embedded in various constructions. The author considers the result of embedding such sentences under negation and verbs of propositional attitude. He also examines the question of why some uses of underspecified expressions are felicitous and others aren’t. This investigation yields the notion of a context being appropriate for a sentence (LF), where a context is appropriate for a sentence containing an underspecified expression if the sentence is felicitous in that context. Finally, some difficulties are covered that arise in virtue of the fact that pronouns and demonstratives have some sorts of implications of uniqueness that clash with their being underspecified.

Delta Smelt (Hypomesus transpacificus) Exhibit Wide Variation in Spawning Behavior: An Investigation of Substrate Type, Diel Timing, and Participants

Studies of cultured populations can be invaluable to the conservation of imperiled species for which little is known and whose very low abundance in the wild can preclude studies with robust sample sizes. For example, in endangered delta smelt (Hypomesus transpacificus), conservation measures developed to mitigate population decline are hindered by a lack of knowledge regarding spawning behavior. However, the availability of a cultured population allows important questions about spawning to be addressed experimentally. We examined the effect of substrate type on spawning behavior and egg fertilization success in cultured H. transpacificus under laboratory conditions. We also examined the diel frequency of spawning and the sex and number of spawning participants. We found that the frequency of spawns and resulting egg fertilization success did not differ between sand, gravel, and control (acrylic) substrates. We also demonstrated that spawning was predominantly nocturnal, though rare diurnal spawns were observed. Of the five mature males and five ripe females available within a given trial, spawns included up to seven participants, but most frequently occurred between a single female and one or two males. Our results highlight the wide behavioral variation exhibited by H. transpacificus during spawning, particularly in terms of substrate use, diel timing, and participants. These findings provide the most detailed and experimentally robust data regarding H. transpacificus spawning behavior to date and thereby provide ongoing conservation efforts with much-needed information.

Determinants of Harem Size in a Polygynous Primate: Reproductive Success and Social Benefits

We used long-term data on the variation in harem size in Yunnan snub-nosed monkeys to research the effects of harem size on reproductive success and the ratio of grooming received to given (RGRG). The results suggest that harem holders derive reproductive benefits commensurate with harem size, whereas the females’ reproductive success is unaffected by harem size. Males of larger harems groomed less and had higher RGRG than males of smaller harems. In the case of females, grooming given increased, and RGRG decreased with an increase in harem size. The males’ reproductive success seems to be a driver of harem size maximization. From the females’ perspective, dwindling social benefits appear to set the upper limit for harem enlargement. We also showed that males of monogamous units (‘single-female harems’) invested more into grooming their female, presumably to prevent unit disintegration and loss of mating privileges.

Extinct before discovered? Epactoides giganteus sp. nov. (Coleoptera, Scarabaeidae, Scarabaeinae), the first native dung beetle to Réunion island

We describe a new species of dung beetle, Epactoides giganteussp. nov., from a single female specimen allegedly collected in the 19th century on Réunion island and recently found at the Muséum national d’Histoire naturelle, Paris. This species differs from other species of Epactoides by larger size and a set of other distinctive morphological characters. Epactoides giganteussp. nov. is the first native dung beetle (Scarabaeinae) of Réunion, and its discovery expands the known area of distribution of the genus Epactoides, which was hitherto believed to be endemic to Madagascar. Like other taxa from Madagascar and peripheral islands (e.g., Comoro, Seychelles, Mascarenes), E. giganteussp. nov. may have reached Réunion by over-water dispersal. Given the rapid loss of biodiversity on Réunion island and the fact that no additional specimens were re-collected over the last two centuries, it is very likely that E. giganteussp. nov. has gone extinct. However, we have unconfirmed evidence that the holotype of E. giganteussp. nov. might be a mislabeled specimen from Madagascar, which would refute the presence of native dung beetles on Réunion. We discuss both hypotheses about the specimen origin and assess the systematic position of E. giganteussp. nov. by examining most of the described species of Madagascan Epactoides. Additionally, we provide a brief overview of the dung beetle fauna of Mascarene Archipelago.

Behavioural measurements of hearing-sensitivity in swarming Anopheles coluzzii mosquitoes reveal an unprecedentedly low threshold

BackgroundMale and female mosquitoes of many species mate in swarms consisting of males and uninseminated females; males form station-keeping swarms and mating chases ensue as soon as a male detects the flight tones of a female. The auditory organs of mosquitoes have been reported to be the most sensitive among arthropods, enabling them to track their flying mate by the sound of the female’s flight tones during mating chases. Previous studies on hearing thresholds have mainly used electrophysiological methods, which unfortunately limit the natural behaviour of the mosquitoes. This study explores male auditory behavioural sensitivity to female flight tones.MethodsWe developed a behavioural method for measuring hearing sensitivity in swarming male mosquitoes. Free-flying male Anopheles coluzzii mosquitoes were released in a large arena (∼2 m high × 2 m × 1 m) with a visually conspicuous object on the ground that stimulates swarming behaviour consisting of elliptical flight pattern over the object. Males were exposed to a range of natural and synthetic played-back sounds of female flight emanating from a speaker located at the same height as the swarm centre and 0.9 m away from it. We monitored the responses of males to female sound by recording the flight-tone and flight-dynamic responses of males. Calibrated sound-levels were measured at the swarm centre; the changing distances between the speaker and the flying males as well as other measurement uncertainties were taken into account to estimate the sound levels that males were effectively exposed to.ResultsWe show that the mean male behavioural threshold of particle-velocity hearing lies between 13-20 dB SVL (95%-CI). A conservative estimate of 20 dB SVL (i.e., less than a particle velocity of 0.5 µm/s) is already 12 to 26 dB less than most of the published electrophysiological measurements on Johnston’s organ sensilla. Our results confirm, under laboratory conditions, the high behavioural hearing-sensitivity of swarming mosquitoes recently found with swarming Aedes communis in the field, and suggest a hearing threshold at least two times lower than that of published results (26 dB SVL or 1 µm/s particle-velocity). In addition, we established that 1) the first harmonic of Anopheles coluzzii female flight sound is sufficient for males to detect her presence, 2) males respond with a greater amplitude to single-female sounds than to group-female sounds and 3) males respond to the playback of single-female sound as much as to pure-sound at a constant frequency and amplitude.