Biofluorescence has been reported in all extant chelicerate orders, but genus- or species-specific documentation remains limited. This gap is particularly noticeable in amblypygids (tailless whip spiders), where detailed descriptions of biofluorescence have not yet been fully developed. Here, we present the first description and photographic documentation of suspected biofluorescent patterns in Mesoamerican amblypygids. We collected two specimens, likely belonging to the genera Paraphrynus Moreno, 1940 and Phrynus Lamark, 1801, from an urban area on the Pacific coast of Guanacaste, Costa Rica. Under 365 nm light, these specimens appeared to display blue-green fluorescence at the joints and soft cuticle segments. Our findings suggest that further research is necessary to confirm the presence of fluorophores by using techniques such as spectrofluorimetry, to explore the ecological role of biofluorescence, and to describe biofluorescent patterns across amblypygid taxa.
Scorpions mainly feed on insects and other invertebrates. However, several species include small vertebrates in their diets. Here, we report a case of lizard consumption by a Mediterranean scorpion. This is the first documented case of Aegaeobuthus gibbosus (Brulle, 1832) (Buthidae) preying on the gecko Mediodactylus kotschyi, adding to a limited body of reports of lizard predation by European scorpions.
Polysphinctine wasps have evolved highly specialized life strategies that allow them to parasitize different spider hosts effectively. In this report, we document juvenile orchard orb-weavers Leucauge tessellata (Thorell, 1887) singly carrying larvae of a polysphinctine wasp from the Acrodactyla quadrisculpta-group. The wasp was identified using its morphological characteristics, mode of parasitism, and mt-COI phylogenetic analysis. Observations revealed that all three Acrodactyla sp. larvae collected were attached to the left mediolateral abdomen of the host spiders, where they consumed hemolymph until pupation. Before being killed by their parasitoids, host spiders exhibited modified web-building behavior, constructing a reduced cocoon web in place of the characteristic orb web of L. tessellata. Our PLS-PM analysis showed a significant negative correlation between the host spider's developmental stage and the parasitism rate (P = 0.02), which suggests that Acrodactyla sp. wasps selectively target juvenile L. tessellata, likely because they are less able to dislodge the larva from its attachment site compared to adult spiders. We speculate that the apparently consistent site of larval attachment in this specific spider-parasitoid interaction may represent a specific host-utilization adaptation in the observed Acrodactyla sp. wasps. Further investigation is warranted to strengthen evidence for our interpretation of this behavior and to explore its evolutionary implications.
Adult female spiders of the brown widow spider, Latrodectus geometricus CL Koch, 1841, lay multiple egg sacs during their lifetime, with each egg sac containing between 50 and 250 offspring. The mother supplements her developing embryos with additional lipids and proteins, and the spiderlings undergo one molt within the egg sac before emerging. Thereafter, the spiderlings may remain in the mother's web for up to several days, and then disperse and build their own webs and seek prey. Prey availability, however, is unpredictable, and may differ among habitats. For synanthropic spiders like L. geometricus, that live in close proximity with human dwellings, prey availability might vary considerably. Here, we compared mortality, growth and development of the brown widow spider, Latrodectus geometricus, from neonate to adult under two different prey availability regimes. Growth curves were plotted by weighing spiderlings fed weekly or every three weeks on fruit flies and then blow flies or crickets. Mortality rates were significantly higher when spiderlings received less prey, and only 7 spiderlings survived when fed intermittently, whereas of those fed weekly, approximately 60% reached adulthood. Males developed linearly, molted a mean of approximately 4 times, and attained maximum body masses after 100 days, whereas females developed exponentially, molted 8-9 times, and reached maximum body masses after 170 days. The growth rate of males was consistent across different instars whereas it was highest in later female instars. Mature males were less than 1% as large as mature females, revealing extreme sexual size dimorphism in this species.
The interaction of polysphinctine ectoparasitoids with their 2D-web-building spider hosts is characterized by alterations in web-building behavior, where the manipulated spider builds a so-called "cocoon web", a unique structure that is important for pupal survival. Alteration of the web architecture of spider hosts building a 3D web has been observed only rarely. We documented interactions between the parasitoid Acrodactyla degener and the linyphiid sheet-web-building spider Mughiphantes mughi (Fickert, 1875), a new host from spruce stands in central Europe. When the parasitoid reached the final instar larva, the spider was killed and consumed on the underside of the sheet web (the typical spider position on the sheet web), after which the parasitoid larva produced a cocoon incorporated horizontally into the sheet of the web. We identified the reduction of some parts of the web of parasitized M. mughi, but the origin and the function of this reduction are not clear.
