New records and habitat modeling of Limnatis paluda (Praobdellidae) in Southern Uzbekistan

Limnatis paluda (Tennent, 1859) is a hematophagous leech of medical and veterinary importance, previously known in Uzbekistan mainly from the Fergana Valley and Samarkand Region. This study reports new records of the species from the Surkhandarya and Kashkadarya regions, representing the first documented occurrence of L. paluda in Southern Uzbekistan. A total of 475 specimens were collected from 11 localities in freshwater springs and pools at altitudes of 424–1,947 m a.s.l. Species identification was based on morphological characters and corroborated by DNA barcoding of the mitochondrial cytochrome c oxidase subunit I (COI) gene. The newly generated sequence (GenBank accession PX916451) was placed within the principal L. paluda clade with 99–100% bootstrap support and was clearly separated from L. nilotica and L. anouarensis. A median-joining network based on 21 L. paluda sequences and a 443 bp alignment recovered four haplotypes, with Southern Uzbekistan sequence belonging to the widespread central haplotype, a pattern consistent with low mitochondrial divergence among the sampled sequences. Habitat suitability was modeled using 22 spatially unique occurrence cells. Following Pearson correlation screening, five bioclimatic predictors (BIO4, BIO6, BIO13, BIO15, and BIO18) were retained for the final MaxEnt model. Five-fold cross-validation yielded a mean test AUC of 0.882 ± 0.049. Using the mean 10th-percentile training-presence threshold of 0.3806, the currently suitable habitat area was estimated at approximately 104,595 km². Under the SSP3-7.0 climate scenario for 2040, suitable habitat was projected to decrease to approximately 87,022 km², representing a reduction of 17,573 km² (16.8%). These findings extend the documented distribution of L. paluda in Central Asia, provide molecular corroboration of its occurrence in Southern Uzbekistan, and establish a quantitative baseline for assessing future changes in habitat suitability.

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