Rediscovery of the lost skink Proscelotes aenea and implications for conservation.

Biodiversity loss is recognized as a grand challenge of the twenty-first century but ascertaining when a species is "lost" can be incredibly difficult-since the absence of evidence is not evidence of absence. This may be a relatively easy task for large and conspicuous animals, but extremely difficult for those living hidden lives or at low population sizes. We showcase this challenge by focusing on Africa's montane skink, Proscelotes aenea (Barbour & Loveridge 1928). In this study, we embarked on a year-long intensive survey to find this fossorial species in Lumbo, Northern Mozambique, the only remaining location where it may still occur but was recorded for the last time over 100 years ago. We located the species already after 20 days of intensive and targeted searching by five members of our team. The finding allowed us to describe, for the first time, details on the biology and ecology of the species, alongside photos and videos of live specimens (including a pregnant female), and to sequence DNA from the species, which we used to infer the phylogenetic placement. Our combined 12S and 16S phylogenetic analysis weakly suggest that the genus Proscelotes may not be monophyletic and therefore requires further phylogenetic work and potentially taxonomic revision. We also gathered evidence of a possible decrease in population abundance and, based on the species' ecology, we identified urbanization as a potential key threat, which could lead to the local or global extirpation of the species. We call for urgent conservation actions that help protect the future of the montane skink, and additional surveys to map its full distribution. As countries now work towards implementing the goals and targets of the Kunming-Montreal Global Biodiversity Framework, our study demonstrates the need for proper investments in biodiversity inventories and monitoring in order to halt species extinctions by 2030.

Dilute bird nectars: viscosity constrains food intake by licking in a sunbird.

Floral nectars of bird-pollinated plants are relatively dilute. One hypothesis proposed to explain this concerns the difficulty for birds of drinking nectar of high viscosity. We examined the effects of viscosity, separately from those of sugar concentration, on feeding by captive whitebellied sunbirds (Cinnyris talatala). Viscosities of artificial nectar (sucrose solutions ranging in concentration from 0.25 to 1.5 mol/l) were altered with Tylose, an inert polysaccharide. Food consumption was measured over 3 h, and lick frequency and duration were recorded using photodetection devices on feeding apertures too small for the bill but large enough for the extended tongue. Volumetric intake rates (ml/s) were inversely proportional to nectar viscosity, and were similar over the range of sucrose concentrations when viscosity was held constant. Sucrose intake rates (mg/s) remained the same on pure sucrose solutions, but they decreased with increasing viscosity at a constant sucrose concentration. Lick frequencies and tongue loads were reduced at high viscosities, and lick duration increased, which confirms that sunbirds take longer to ingest viscous solutions. Licking behavior was remarkably similar in birds feeding on different sucrose concentrations if viscosity was held constant. Nectar ingestion rate is determined by viscosity; however, total food intake is mainly modulated by sugar concentration. Similar effects of food viscosity have been observed in insects that suck nectar.

A new Reed Frog (Hyperoliidae: Hyperolius) from coastal northeastern Mozambique.

A new species of African reed frog (genus Hyperolius Rapp, 1842) is described from the Coastal Forests of the Eastern Africa Biodiversity Hotspot in northeastern Mozambique. It is currently only known from less than ten localities associated with the Mozambican coastal pans system, but may also occur in the southeastern corner of Tanzania. Phylogenetic reconstructions using the mitochondrial 16S marker revealed that it is the sister taxon of Hyperolius mitchelli (>5.6% 16S mtDNA sequence divergence) and forms part of a larger H. mitchelli complex with H. mitchelli and H. rubrovermiculatus. The new species is distinguished from other closely related Hyperolius species by genetic divergence, morphology, vocalisation, and dorsal colouration.

Heterothermy in two mole-rat species subjected to interacting thermoregulatory challenges.

Maintaining a high and constant body temperature (T(b) ) is often viewed as a fundamental benefit of endothermy, but variation in T(b) is likely the norm rather than an exception among endotherms. Thus, attempts to elucidate which factors cause T(b) of endotherms to deviate away from the T(b) that maximizes performance are becoming more common. One approach relies on an adaptive framework of thermoregulation, used for a long time to predict variation in T(b) of ectotherms, as a starting point to make predictions about the factors that should lead to thermoregulatory variation in endotherms. Here we test the predictions that when confronted with thermoregulatory challenges endotherms should (1) become more heterothermic, (2) lower their T(b) setpoint, and/or (3) increase behavioral thermoregulation (e.g., activity levels or social thermoregulation). We exposed two species of relatively homeothermic mole-rats to two such challenges: (a) ambient temperatures (T(a)) well below the thermoneutral zone and (b) increased heat loss caused by the removal of dorsal fur. In general, our results support the adaptive framework of endothermic thermoregulation with each species conforming to some of the predictions. For example, Mashona mole-rats (Fukomys darlingi) increased heterothermy as T(a) decreased, highveld mole-rats (Cryptomys hottentotus pretoriae) displayed lower T(b) 's after shaving, and both species increased behavioral thermoregulation as T(a) decreased. This suggests that there is some merit in extending the adaptive framework to endotherms. However, none of the three predictions we tested was supported under all experimental conditions, reiterating that attempts to determine universal factors causing variation in T(b) of endotherms may prove challenging.

Jettisoning ballast or fuel? Caudal autotomy and locomotory energetics of the Cape dwarf gecko Lygodactylus capensis (Gekkonidae).

Many lizard species will shed their tail as a defensive response (e.g., to escape a putative predator or aggressive conspecific). This caudal autotomy incurs a number of costs as a result of loss of the tail itself, loss of resources (i.e., stored in the tail or due to the cost of regeneration), and altered behavior. Few studies have examined the metabolic costs of caudal autotomy. A previous study demonstrated that geckos can move faster after tail loss as a result of reduced weight or friction with the substrate; however, there are no data for the effects of caudal autotomy on locomotory energetics. We examined the effect of tail loss on locomotory costs in the Cape dwarf gecko Lygodactylus capensis ( approximately 0.9 g) using a novel method for collecting data on small lizards, a method previously used for arthropods. We measured CO(2) production during 5-10 min of exhaustive exercise (in response to stimulus) and during a 45-min recovery period. During exercise, we measured speed (for each meter moved) as well as total distance traveled. Contrary to our expectations, tailless geckos overall expended less effort in escape running, moving both slower and for a shorter distance, compared with when they were intact. Tailless geckos also exhibited lower excess CO(2) production (CO(2) production in excess of normal resting metabolic rate) during exercising. This may be due to reduced metabolically active tissue (tails represent 8.7% of their initial body mass). An alternative suggestion is that a change in energy substrate use may take place after tail loss. This is an intriguing finding that warrants future biochemical investigation before we can predict the relative costs of tail loss that lizards might experience under natural conditions.

Nectar intake of white-bellied sunbirds (Cinnyris talatala): can meal size be inferred from feeding duration?

A positive relationship between feeding duration and meal size of avian nectarivores has often been assumed in earlier studies. We investigated whether feeding duration can be used as a surrogate for the amount of sugar solution ingested by white-bellied sunbirds, Cinnyris (Nectarinia) talatala. Feeding durations of sunbirds consuming three sucrose concentrations (10%, 20%, and 40% w/w) were measured using an infrared photodetection system, and the amounts consumed were recorded simultaneously by weighing the feeder throughout the experiment. For all three diet concentrations, a positive relationship was found between the time spent feeding per 30 min and the mass consumed. Therefore, feeding duration is demonstrated to be an index of the amount ingested on a particular sugar concentration. The rate of ingestion, however, depended on the sugar concentration, with the highest rate at the lowest concentration of 10% and the lowest rate at the 40% concentration. Less total time was spent feeding on the 20% solution than on the 10% solution, but time increased on the 40% diet because of viscosity effects. There appeared to be a weak relationship between feeding patterns and sex, but this was not significant, probably because of interindividual variation.