Can the Dynamic Colouration and Patterning of Bluelined Goatfish (Mullidae; Upeneichthys lineatus) Be Perceived by Conspecifics?

Bluelined goatfish (<i>Upeneichthys lineatus</i>) exhibit dynamic body colour changes and transform rapidly from a pale, buff/white, horizontally banded pattern to a conspicuous, vertically striped, red pattern when foraging. This red pattern is potentially an important foraging signal for communication with conspecifics, provided that <i>U. lineatus</i> can detect and discriminate the pattern. Using both physiological and behavioural experiments, we first examined whether <i>U. lineatus</i> possess visual pigments with sensitivity to long (“red”) wavelengths of light, and whether they can discriminate the colour red. Microspectrophotometric measurements of retinal photoreceptors showed that while <i>U. lineatus</i>lack visual pigments dedicated to the red part of the spectrum, their pigments likely confer some sensitivity in this spectral band. Behavioural colour discrimination experiments suggested that <i>U. lineatus</i>can distinguish a red reward stimulus from a grey distractor stimulus of variable brightness. Furthermore, when presented with red stimuli of varying brightness they could mostly discriminate the darker and lighter reds from the grey distractor. We also obtained anatomical estimates of visual acuity, which suggest that <i>U. lineatus</i> can resolve the contrasting bands of conspecifics approximately 7 m away in clear waters. Finally, we measured the spectral reflectance of the red and white colouration on the goatfish body. Visual models suggest that <i>U. lineatus</i> can discriminate both chromatic and achromatic differences in body colouration where longer wavelength light is available. This study demonstrates that <i>U. lineatus</i> have the capacity for colour vision and can likely discriminate colours in the long-wavelength region of the spectrum where the red body pattern reflects light strongly. The ability to see red may therefore provide an advantage in recognising visual signals from conspecifics. This research furthers our understanding of how visual signals have co-evolved with visual abilities, and the role of visual communication in the marine environment.

An unusual body colouration of Ceylon roughside snake (Aspidura ceylonensis)

The small sized, non-venomous, and fossorial colubrid snake genus Aspidura Wagler, 1830 is endemic to Sri Lanka. Aspidura ceylonensis (Günther, 1858) is rare and restricted to mid-elevation to montane and sub-montane forests at elevation of 500–1300 m a.s.l. in the Central Highlands and the Knuckles massif. It is found in cool and well-shaded forest areas, with thick moist leaflitter, woody debris, and loose soil. The usual adult body coloration on dorsum is dark reddish or dark orange, rarely yellowish, with a continuous black vertebral line and two rows of dorsolateral black spots along the body.

A new species of Pareas (Squamata, Pareidae) from southern Vietnam

We describe a new species of pareid snake from the Di Linh Plateau in Lam Dong Province of southern Vietnam based on morphological and molecular evidence. Pareas temporalissp. nov. is distinguished from its congeners by having the combination of yellow-brown body colouration; hexagonal-shaped frontal, with lateral sides parallel to the body axis; 16–17 temporals, with 4–5 anterior temporals; loreal and prefrontal not contacting eye; 2–3 preoculars; two suboculars; 2–3 postoculars; 8–9 supralabials; 8–9 infralabials; 15–15–15 dorsal scale rows, all keeled, three vertebral scale rows enlarged; 191 (+1 preventral) ventrals, smooth; 92 subcaudals, all divided; undivided anal scale; two postocular stripes; and a solid dark brown vertebral stripe extending from rear of nuchal collar along the entire length of body and tail. Phylogenetic analyses of mitochondrial DNA data recovered the new species to be nested within the P. carinatus complex and to be the sister taxon to P. nuchalis from Borneo.

Colour and motion affect a dune wasp’s ability to detect its cryptic spider predators

Ambush predators depend on cryptic body colouration, stillness and a suitable hunting location to optimise the probability of prey capture. Detection of cryptic predators, such as crab spiders, by flower seeking wasps may also be hindered by wind induced movement of the flowers themselves. In a beach dune habitat, Microbembex nigrifrons wasps approaching flowerheads of the Palafoxia lindenii plant need to evaluate the flowers to avoid spider attack. Wasps may detect spiders through colour and movement cues. We tracked the flight trajectories of dune wasps as they approached occupied and unoccupied flowers under two movement conditions; when the flowers were still or moving. We simulated the appearance of the spider and the flower using psychophysical visual modelling techniques and related it to the decisions made by the wasp to land or avoid the flower. Wasps could discriminate spiders only at a very close range, and this was reflected in the shape of their trajectories. Wasps were more prone to making errors in threat assessment when the flowers are moving. Our results suggest that dune wasp predation risk is augmented by abiotic conditions such as wind and compromises their early detection capabilities.

The hunt for the Blue tree monitor on Batanta Island, Indonesia: Subsistence on a treasure?

The tree monitors, Varanus (Hapturosaurus) are highly valued in international pet trade. These lizards are somewhat striking in their colouration, among which is the Blue tree monitor, Varanus macraei. Body colouration of this species is dominantly blue, which is unique to this monitor lizard species. This distinctive colouration together with its limited distribution has put the species as high-priced export commodity for at least 20 years. Because the lizard is endemic to Batanta Island and the nearby islets in the Raja Ampat Islands, Indonesia, we made a trip to the islands in 2019. We visited the village of Amdui on Batanta, where we made several casual interviews with hunters. Here we report results of our interviews and brief survey on the habitats of V. macraei, in order to identify the roles of local hunters in the trade of tree monitors for international pet markets. Some residents of Amdui have been in search for Blue tree monitors and other monitor lizard species since mid1990s and continue their hunt until very recently for fast cash. Because hunting is yet a large part of their culture more than farming, villagers rely on this method for subsistence. We recommend a socio-cultural approach to inform hunters on the idea of sustainability of harvest, for which a stable livelihood will be a possible consequence.

Parallel shifts of visual sensitivity and body colouration in replicate populations of extremophile fish.

Visual sensitivity and body pigmentation are often shaped by both natural selection from the environment and sexual selection from mate choice. One way of quantifying the impact of the environment is by measuring how traits have changed after colonization of a novel habitat. To do this, we studied Poecilia mexicana populations that have repeatedly adapted to extreme sulphidic (H2S containing) environments. We measured visual sensitivity using opsin gene expression, as well as body pigmentation and water transmission for populations in four independent drainages. Both visual sensitivity and body pigmentation showed significant parallel shifts towards greater medium wavelength sensitivity and reflectance in sulphidic populations. The light spectrum was only subtly different between environments and overall, we found no significant correlations between the light environment and visual sensitivity or body pigmentation. Altogether we found that sulphidic habitats select for differences in visual sensitivity and pigmentation; our data suggest that this effect is unlikely to be driven purely by the water's spectral properties and may instead be from other correlated ecological changes.

Avoiding attack: How dune wasps leverage colour and motion to detect their cryptic spider predators

Ambush predators depend on cryptic body colouration, stillness and a suitable hunting location to optimise the probability of prey capture. Detection of cryptic predators, such as crab spiders, by flower seeking wasps may also be hindered by wind induced movement of the flowers themselves. In a beach dune habitat, as Microbembex nigrifrons wasps approach flowerheads of the Palafoxia lindenii plant, they need to evaluate the flowers and avoid landing on crab spider occupied flowers. Wasps may detect spiders through colour and movement cues. We tracked the flight trajectories of dune wasps as they approached occupied and unoccupied flowers under two movement conditions; when the flowers were still or moving. We simulated the appearance of the spider and the flower using psychophysical visual modelling techniques and related it to the decisions made by the wasp to land or avoid the flower. Wasps could discriminate spiders only at a very close range, and this was reflected in the shape of their trajectories. Wasps were more prone to making errors in threat assessment when the flowers are moving. Our results suggest that dune wasp predation risk is augmented by abiotic conditions such as wind and compromises their early detection capabilities.

Nothobranchius elucens, a new species of seasonal killifish from the upper Nile drainage in Uganda (Cyprinodontiformes: Nothobranchiidae)

Nothobranchius elucens, new species, from a seasonal habitat in the Aringa system of the Achwa River in the upper Nile drainage in northern Uganda, is described. It belongs to the N. rubroreticulatus species group, whose members are characterised by male coloration of anal and caudal fins with slender light blue subdistal band and slender dark distal band. Nothobranchius elucens is distinguished from all other members of the genus by the following characters in males: body colouration golden-grey with brown scale margins creating irregular vertical stripes on trunk; anal fin yellow with brown spots proximally, with slender brown median band, followed by a slender light blue subdistal band and a slender black distal band; caudal fin brown proximally and medially, followed by a slender light blue subdistal band and a slender black distal band; dorsal fin golden with irregular brown stripes and narrow light blue subdistal band and with narrow black distal band. Furthermore, it differs from the closest known relative, N. taiti, also by the morphometric characters of having a smaller head length of 29.5–33.1 % SL; smaller prepectoral length of 31.2–33.9 % SL; greater head depth of 81–87 % HL; greater interorbital width of 43–49 % HL; and greater caudal peduncle length of 145–152 in % of its depth.