Possible shell disease in 100 million-year-old crabs

Abstract

Modern organisms exhibit evidence of many diseases, but recognizing such evidence in fossils remains difficult, thus hampering the study of the evolution of disease. We report on 2 molts of the goniodromitid crabs Distefania incerta and Goniodromites laevis from the mid-Cretaceous (late Albian) of Spain, with both species exhibiting damage to the dorsal carapace in otherwise well-preserved specimens. The subcircular to quadratical holes, found in < 0.2% of the specimens, resemble damage caused by bacterial infections on the cuticle of modern decapods in terms of size and shape. Abiotic damage, predation, and encrustation followed by damage to the shell provide less satisfactory explanations, although these agents cannot be completely excluded from a role in shell disease etiology. We hypothesize that the observed fossil lesions are caused primarily by bacterial disease that started prior to molting, with or without other agents of initiation. If correct, this is the only known example of such bacterial infections in decapod crustaceans from the fossil record thus far, pushing back the evolutionary history of this type of shell disease by ~100 million years.

Shell Disease Syndrome Is Associated with Reduced and Shifted Epibacterial Diversity on the Carapace of the Crustacean Cancer pagurus

“…Leinberger et al ( 20 ), who studied the epibacterial community of the deep-sea galatheid Munidopsis alvisca , did not observe lesions or other morphological changes in the carapace that would indicate carapace disease in any of these animals from 2000 m depth. However, shell disease might be a normal phenomenon in crustaceans, possibly occurring also without anthropogenic influences or impacts of climate change ( 43 ). To target specific risks for crustaceans, broader approaches in combination with environmental modeling are necessary to understand whether bacterial community dysbiosis becomes problematic for species such as C. pagurus in their range of distribution and context of climate change.…”

Treatise Online no. 178: Part R, Revised, Volume 1, Biotic Interactions

“…The sole occurrence of shell disease recognized in the fossil record was that of two species of late Albian dromiacean crabs, Distefania incerta (Bell, 1863) and Goniodromites laevis Van Straelen, 1940), from Spain (Fig. 3) (Klompmaker, Chistoserdov, & Felder, 2016). The specimens are part of a quite diverse, normal marine assemblage setting (Klompmaker, 2013).…”

A new approach to the systematics of Laeviprosopon (Brachyura: Homolidae), with remarks on molting process of the early brachyurans

“…There are only large, poorly calcified areas on the latero-ventral sides in modern representatives -the branchiostegites (Ng et al, 2008). The molting lines in these regions are clearly visible on the flanks or in ventral view in fossils ascribed to Homolodromioidea (e.g., Schweitzer and Feldmann, 2008;Klompmaker et al, 2011Klompmaker et al, , 2012Klompmaker et al, , 2016Klompmaker et al, , 2020Starzyk, 2013Starzyk, , 2015a, but they are rarely illustrated.…”