The genus Cirolanides was erected 130 years ago with description of Cirolanides texensis Benedict 1896: one of the first groundwater-obligate invertebrates from Texas. Since then, the species has been documented across a wide range of karst aquifers in central and Trans-Pecos Texas, USA, and northern Mexico, spanning over 145,000 km2. Later work by Krejca suggested that additional diversity existed, but revisionary taxonomic work did not begin until 2019 with description of a second species; Cirolanides wassenichae Schwartz, Hutchins, Schwartz, Hess & Bonett, 2019. Here, we present preliminary results describing two additional species and redescribing the genus and type species.
A combination of morphological and molecular data (mitochondrial COI and nuclear 28S) supports the new taxa and confirms that additional undescribed diversity exists. What was once thought to be a single widespread species is clearly a species complex, with co-occurrence of at least three species at some sites. The most recent work shows that Cirolanides texensis s. str. has a relatively small range and primarily occurs in deeper confined aquifer settings, with other species having different habitats and ranges. Our findings bring the number of Cirolanides spp. confirmed from Texas to four, and the combination of molecular and morphological data provide a firm foundation for clearly delineating and describing more diversity in the future.
After 130 years of investigation, groundwater diversity in Texas remains under studied and under sampled. The description of two new Cirolanides spp. contributes to the knowledge base but revealed even greater diversity than was previously known. Despite the rate of taxonomic descriptions lagging the rate at which new groundwater species are discovered in Texas, more species are being described now than at any time in the past. This, in combination with new data on species occurrences, should be used to better manage and conserve groundwater fauna and their aquifer habitats in Texas.