The largest fossil of the segmented spider Parvithele muelleri Wunderlich, 2017 (Mesothelae: Parvithelidae) from Cretaceous Burmese amber

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  The largest fossil of the segmented spider Parvithele muelleri Wunderlich, 2017 (Mesothelae: Parvithelidae) from Cretaceous Burmese amber Abstract A new specimen of the fossil spider Parvithele muelleri Wunderlich, 2017 (Araneae: Mesothelae) is described from the mid-Cretaceous (ca. 99 Ma) Burmese amber of Myanmar. Like the original holotype, the new specimen is a mature male, which clearly preserves a series of tibial macrospines, similar to the condition in the extant genus Liphistius Schiødte, 1849. Given that the single extant mesothele family, Liphistiidae, is predicted to have radiated ca. 39–58 million years ago, the occurrence of somewhat modern-looking male pedipalp spination in older fossil mesotheles is of considerable interest. The new specimen also shows spinnerets in a relatively posterior position, although variability observed in extant species suggests that this trait may be of limited systematic value. Of particular note is the presence of a large and well-dev...

One small step for citizens, one giant leap for science: iNaturalist records boost our understanding of the evolution of parental care in a clade of arachnids

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One small step for citizens, one giant leap for science: iNaturalist records boost our understanding of the evolution of parental care in a clade of arachnids 

Abstract

Citizen-science platforms have become powerful tools for documenting natural history, but their potential for reconstructing behavioural evolution remains largely unexplored. Here, we combine field and laboratory records with a systematic survey of iNaturalist observations to investigate the evolution of parental care in the superfamily Gonyleptoidea, the clade containing the most documented cases of care in harvestmen. We report 85 new records of parental behaviour (78 of maternal or paternal care and seven of no care), more than doubling the number of species with available data. These records, together with all published information, were mapped on to a newly assembled supertree of 165 species spanning nine families. Transition rates revealed that maternal care arises exclusively from ancestors without care, whereas paternal care evolves through two routes—from no care and from maternal care—suggesting distinct selective pressures underlying its repeated origins. Transitions from parental care back to no care are frequent in both sexes, suggesting that alternative egg-protection strategies (e.g. oviposition in cryptic sites and debris coverings) may compensate for the absence of parental attendance, while avoiding the costs of prolonged care. Our findings highlight the remarkable evolutionary lability of parental care in Gonyleptoidea and demonstrate that citizen-science data can substantially accelerate macroevolutionary research.

Machado, G., Buzatto, B. A., Caetano, D. S., Flores, E., García-Hernández, S., Grob, O., Grossel, L. A., Höfer, H., Kury, A. B., Lancheros, H., Medrano, M., Oyarzún, C., Pérez-Schultheiss, J., Pinto-da-Rocha, R., Robledo-Ospina, L. E., Sáenz-Mancheno, J., Solano-Brenes, D., Quesada-Hidalgo, R., Triana, E., . . . Villarreal, O. (2026). One small step for citizens, one giant leap for science: INaturalist records boost our understanding of the evolution of parental care in a clade of arachnids. Zoological Journal of the Linnean Society, 207(2). https://doi.org/10.1093/zoolinnean/zlag061