A morphological comparison of Holospira monclovana and Holospira picta (Gastropoda: Urocoptidae) using X-ray computed tomography

Abstract

This study was undertaken to re-evaluate the taxonomic placement of two species of xeric-adapted holospirids from near Monclova, Coahuila, Mexico using techniques unavailable to researchers at the time of the original descriptions of these species. X-ray computed tomography was used to scan the complete series of Holospira monclovana (n=24, including holotype) and of Holospira picta (n=27, including holotype), as well as 26 of another series of specimens (assigned to Holospira picta by the original author) from approximately 35 km southeast of Monclova. The program ImageJ was used to analyze Xray CT scans of all specimens. Analyses of Similarities (ANOSIM) were conducted using the statistical suite R to compare the three populations, both pairwise and all together (Null hypothesis: R≈0; dissimilarities within groups ≥ dissimilarities between groups). Analysis shows all three populations to be statistically distinct (R=0.398, p<0.001), supports the retention of H. monclovana within subgenus Holospira, and supports reassignment of both populations of H. picta to the subgenus Bostrichocentrum.