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Two new populations of Pyrgulopsis were found in springs in the Chihuahuan desert region of Texas. Pyrgulopsis Call & Pilsbry, 1886 are a diverse group of snails occupying freshwater springs, usually narrow-range endemics limited to a single spring. Their small ranges confer substantial conservation concern as the drying or disturbance of a single spring can lead to their extinction. We use mitochondrial COI and nuclear LSU sequences, shell morphometrics, and anatomical features to distinguish a new species of Pyrgulopsis endemic to the Big Bend region of Texas.

Pyrgulopsis Call Pilsbry, 1886 is a genus of small (<5 mm) spring snails, usually endemic to single freshwater springs. Two new populations of Pyrgulopsis found in very small, isolated springs and spring runs in the mainstem Rio Grande watershed of western Texas are distinguished from congeners. Mitochondrial and nuclear sequences, morphometrics, and morphological characteristics support Pyrgulopsis rubra sp. nov. and Pyrgulopsis harrymilleri sp. nov. as distinct from other known Pyrgulopsis species, including the geographically proximate P. metcalfi.

Between 2015 and 2017, 58 ostracod taxa were collected at 30 locations in 111 samples from the hyporheic zone of surface streams in Texas, U.S.A. Six new species (Bradleycypris foresteri n. sp., Bradleystrandesia macula n. sp., Pseudocandona lordi n. sp., Indocandona rusti n. sp., Stenocypris sancari n. sp., Cyclocypris dalyana n. sp.) are described based on carapace and soft body parts. Additionally, 17 species and two genera (Vestalenula and Indocandona) are presented as new records for Texas, and Indocandona rusti n. sp. is the first record of the genus outside India. Taxonomic positions of the new species are discussed along with ecological information. One-hundred and six nonmarine ostracod species are now reported from Texas. However, ongoing studies suggest that actual species richness is much higher.

Cirolanides wassenichae sp. nov., is described from the phreatic zone of the Edwards Aquifer, Texas, USA where it is sympatric with Cirolanides texensis Benedict, 1896. Its status as a new species is based on both morphological and molecular data. Number of antennula articles (3-5 vs 9-15), size (mean sizes of 9.5 and 8.8 mm vs 11.1 and 10.4 mm for males and females, respectively), morphology of pereopods 1-3 (haptorial to semi-haptorial in 1-3 vs only 1 haptorial), and shape of pleotelson (squared, slightly indented vs rounded) are key morphological characteristics that distinguish C. wassenichae sp. nov. from C. texensis. Phylogenies based on cytochrome oxidase 1 and large ribosomal subunit 28S show that divergent morphologies correspond to reciprocally monophyletic groups for both nuclear and mitochondrial datasets. The genus Cirolanides is in need of revision, as our description of C. wassenichae sp. nov. renders C. texensis paraphyletic.

Okan Külköylüoğlu, Derya Akdemir, Mehmet Yavuzatmaca, Benjamin F. Schwartz, and Benjamin T. Hutchins (2017) A new ostracod species, Cypria lacrima sp. nov. (Cyclocypridinae) is proposed from an artesian well in Hays County, Texas, U.S.A. The species differs from its conspecies with the following characteristics: unique shape and pit ornamentation on carapace, absence of "e" and "g" setae on both walking and cleaning legs, long gamma seta on Mandibular palp, asymmetric clasping organs and differences in the shape and size of other cheatotaxial parts. A detailed comparison among the species of the genus is provided along with ecological implications. This report increases the geographic distribution of the genus in the southern USA.

Lacrimacandona n. gen. with its type species Lacrimacandona wisei n. sp. from the San Marcos artesian well on the Texas State University campus (Hays County, Texas, USA) is proposed as a new genus of the subfamily Candoninae. The new species is sexually dimorphic, and so far no congeneric species have been found. The new genus has the following distinguishing characters: subtriangular carapace tapering posteriorly, uropod with a claw-like anterior seta and two short claws, one long "a" setae on male maxilliped, very large asymmetric clasping organs in males, unique shape and size of hemipenis, and unique occurrence of setae on segments.

The prevailing paradigm in subterranean ecology is that below-ground food webs are simple, limited to one or two trophic levels, and composed of generalist species because of spatio-temporally patchy food resources and pervasive energy limitation. This paradigm is based on relatively few studies of easily accessible, air-filled caves. However, in some subterranean ecosystems, chemolithoautotrophy can subsidize or replace surface-based allochthonous inputs of photosynthetically derived organic matter (OM) as a basal food resource and promote niche specialization and evolution of higher trophic levels. Consequently, the current subterranean trophic paradigm fails to account for variation in resources, trophic specialization, and food chain length in some subterranean ecosystems. We reevaluated the subterranean food web paradigm by examining spatial variation in the isotopic composition of basal food resources and consumers, food web structure, stygobiont species diversity, and chromophoric organic matter (CDOM), across a geochemical gradient in a large and complex groundwater system, the Edwards Aquifer in Central Texas (USA). Mean δ13C values of stygobiont communities become increasingly more negative along the gradient of photosynthetic OM sources near the aquifer recharge zone to chemolithoautotrophic OM sources closer to the freshwater-saline water interface (FWSWI) between oxygenated freshwater and anoxic, sulfide-rich saline water. Stygobiont community species richness declined with increasing distance from the FWSWI. Bayesian mixing models were used to estimate the relative importance of photosynthetic OM and chemolithoautorophic OM for stygobiont communities at three biogeochemically distinct sites. The contribution of chemolithoautotrophic OM to consumers at these sites ranged between 25% and 69% of total OM utilized and comprised as much as 88% of the diet for one species. In addition, the food web adjacent to the FWSWI had greater trophic diversity when compared to the other two sites. Our results suggest that diverse OM sources and in situ, chemolithoautotrophic OM production can support complex groundwater food webs and increase species richness. Chemolithoautotrophy has been fundamental for the long-term maintenance of species diversity, trophic complexity, and community stability in this subterranean ecosystem, especially during periods of decreased photosynthetic production and groundwater recharge that have occurred over geologic time scales.