First documented breeding population of marbled salamanders (Ambystoma opacum) in Michigan, and rediscovery in west Michigan after a 34 year absence

J. T. Brown, Dawson M. Porter, Noah E. Huber, David A. Mifsud, and Seán Callahan. Verified by Gregory S. Schneider. University of Michigan Museum of Zoology (UMMZ Digital Image 14016–14036; photo voucher).

This locality was first surveyed on 1 April 2023 following a large precipitation and flooding event, where many dozens of larvae were observed in a large vernal pool complex. Voucher photographs were taken of the larvae (UMMZ Digital Images 14016, 14017), and none were removed from the pool. The habitat is a hardwood forested floodplain, with a major river within 1.5 km of the locality, as well as several tributaries. The floodplain habitat is not directly connected to a permanent body of water with fish and consists of a complex of creeks/drainage ditches and expansive clusters of vernal pools. Throughout the rest of 2023, the site was surveyed several more times, yielding more larvae, juveniles, adults, and a single egg mass. In total across 2023, 18 specimens were photographed for a total of 20 digital voucher images. Larvae were again observed in a vernal pool and photographed on 16 April 2023 (UMMZ Digital Image 14018, 14019). A total of eight juveniles and eight adults were found throughout the summer and autumn of 2023. The first two vouchered metamorphosed juveniles were observed on 7 August 2023 (UMMZ Digital Image 14020, 14021). Also on this date, the first adult was discovered under a log in the upland edge of a vernal pool depression, and subsequently photographed (UMMZ Digital Image 14022).

Visit to the site on 8 August 2023 yielded another juvenile, found hiding underneath woody debris within the vernal complex (UMMZ Digital Image 14023). On 16 September 2023, four adults and three juveniles were observed and photographed. Two of the juveniles (UMMZ Digital Image 14024, 14026) were found underneath logs within their vernal depressions, and the third was observed beneath a log sat upon an upland edge of a vernal pool depression (UMMZ Digital Image 14028). Three of the four adults (UMMZ Digital Image 14027, 14029, 14030) were found underneath logs near the upland edge of the vernal complex, and one was found under a log within the vernal pool depression (UMMZ Digital Image 14025). During heavy rain on 17 September 2023 between 1300–1500 h, three adults were observed actively moving throughout the vernal pool complex (UMMZ Digital Image 14031–14033). Two more juveniles were observed that year. A juvenile observed on 7 October 2023 (UMMZ Digital Image 14034) was found under a log within a vernal depression. The last juvenile to be vouchered (UMMZ Digital Image 14035) was found beneath woody debris on the upland edge of the vernal complex on 15 October 2023. An egg mass with 90 eggs was observed on 5 November 2023 (UMMZ Digital Image 14036) underneath woody debris and leaf litter on the edge of a depression; a female was not guarding the egg mass. Overall, metamorphosed juveniles and adults could be found under logs and other debris within dried vernal wetlands and anywhere within 50 m of the wetland edge of the vernal complex.