Honoring the Legacy of Professor Margaretha Delina Hofmeyr (1950–2020)

Margaretha Delina Hofmeyr was born in Kimberly, Northern Cape Province, South Africa, and trained academically in the Western Cape Province, receiving her Master's degree in mammalian physiological ecology at Stellenbosch University and her PhD in ungulate thermoregulation at the University of Cape Town, supervised by the renowned Professor Gideon Louw. Her exemplary research and teaching career spanned 4 decades at the University of the Western Cape, a Historically Black University, where she became chair of the Zoology Department in 1991. Retha was a dedicated and challenging teacher and beloved mentor to several generations of students (undergraduate, graduate, and postdoctoral), many of whom became prominent academics, government officials, and research scientists in South Africa and overseas (Henen 2020).

Retha's keen intellect and robust foundation in physiological ecology and integrative biology (e.g., Gericke et al. 1978; Hofmeyr 1985; Schumann et al. 2005) helped her tackle the challenge of southern Africa's rich tortoise diversity, with 14 native taxa, many endemic, and several endangered species (Fritz et al. 2022). Fostered by collaborations with esteemed colleagues Ernst Baard, Gerald Kuchling, and Uwe Fritz, Retha authored or coauthored more than 60 peer-reviewed chelonian articles with topics ranging from morphometrics and physiology to reproductive ecology, behavior, forensics, phylogeography, phylogenetics, genetics, evolution, and conservation (e.g., Hofmeyr 2004, 2009; Hofmeyr et al. 2005; Leuteritz and Hofmeyr 2007; Loehr et al. 2007; Fritz et al. 2011; Henen et al. 2013; Rhodin et al. 2018; Kuchling and Hofmeyr 2022). Retha and colleagues also published 12 International Union for the Conservation of Nature Red List assessments for sub-Saharan chelonians in 2015 and 2018, and 9 tortoise assessments for South Africa's 2014 Atlas and Red List Assessments for South African Reptiles. . . (Bates et al.).

Retha's colleagues are continuing their research and conservation collaborations in each of these fields, with 5 new articles included in this issue of Chelonian Conservation and Biology. These articles expand our awareness of chelonian diversity, with fundamental advances in morphology (Loehr and Keswick; Leuteritz and Hofmeyr), population ecology (Leuteritz and Hofmeyr), reproductive ecology (Kuchling and Hofmeyr, Hofmeyr and Kuchling), and conservation of the Critically Endangered geometric tortoise (Kiester and colleagues). These articles include aspects of tortoise size and morphology, which are critical in most aspects of tortoise biology (e.g., from species description, taxonomy, and phylogeny to niche partitioning, physiological rates, reproductive ecology, evolution, and ecological and evolutionary consequences of sexual dimorphism).

Retha and her colleagues capture nuances and new patterns in chelonian reproductive ecology, building on the brilliant work of others (e.g., Justin Congdon, Whitfield Gibbons, and a slew of others). The angulate tortoise, Chersina angulata, is relatively common in South Africa, with work by Retha and Gerald Kuchling indicating C. angulata has an unusual reproductive pattern, ovulating and ovipositing single-egg clutches consecutively for most of the year (even in winter), but slowing or suspending ovulations and ovipositioning in the warm, dry season (ca. December through February; Hofmeyr 2004). There is evidence that C. angulata exhibit facultative viviparity (Kuchling and Hofmeyr 2022). Facultative viviparity in C. angulata is supported further here (Kuchling and Hofmeyr, this issue) via flexible embryonic development, including diapause and preovipositional development to Yntema stage 12. These findings may enhance discoveries in other species.

Conservation concerns are frequent with chelonian biologists, and they were with Retha, who coauthored more than 20 publications for Red Listings and general conservation concern. Most recently, her indefatigable energies included a focused, sustained commitment to conserve the critically endangered geometric tortoise Psammobates geometricus (Fig. 1), for which she received the 2014 International Sabin Conservation Prize. In collaboration with the Turtle Conservancy, the Mapula Trust, and CapeNature, she was instrumental in founding the Southern Africa Tortoise Conservation Trust and creating a new reserve protecting a large, significant population of this species in the Breede River Valley, South Africa. One of Retha's major contributions was developing a successful head-starting protocol to recover this species (Juvik 2020). Both of these efforts lay a foundation for critical management efforts in a high-risk and fire-prone landscape, as described by Ross Kiester and colleagues in this issue.

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Retha demonstrated exemplary integrity, compassion, energy, and productivity for her legions of students, friends, and colleagues. Retha's dedication was also exemplified in her family members who are also strong ambassadors for tortoises and turtles (skilpaaie). Margaretha Delina Hofmeyr lived life well, excelling as a scientist, mentor, conservationist, humanitarian, and mother, and she continues to inspire!