Two new species of Pyrgulopsis Call & Pilsbry, 1886 (Mollusca: Caenogastropoda: Hydrobiidae) from springs in the Rio Grande watershed in 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.

ENDEMIC SPRING SNAILS TERRESTRIBYTHINELLA (MOLLUSCA) AS UNUSUAL MATERIAL FOR LARVAL CASE OF CRUNOECIA IRRORATA (TRICHOPTERA: LEPIDOSTOMATIDAE) IN TRANSCARPATHIAN UKRAINE

An unusual larval case of Crunoecia irrorata (Curtis, 1834) (Trichoptera, Lepidostomatidae) was collected in a small stream in Ukrainian Transcarpathia. This larval case consisted mainly of living snails of extremely rare endemic gastropod mollusk of the genus Terrestribythinella Sitnikova, Starobogatov & Anistratenko, 1992 (Gastropoda: Terrestribythinellidae). The larval case, distinguishing characters of C. irrorata larva and its habitat are illustrated. Ecological relations between shell-utilizing caddisfly larvae and mollusks used as material for larval cases are discussed.

Winter torpor in Helix pomatia: regulated defence mechanism or forced inactivity?

We examined Helix pomatia L., 1758 snails to answer two questions. First, is their winter dormancy facilitated by cold-seeking behaviour, or is it rather a passive phenomenon imposed by cold weather? Second, what thermal conditions are necessary to arouse these snails out of torpor in midwinter and in spring? Snails, collected from natural habitats, were placed in a temperature-gradient apparatus. Their thermal preference was recorded for 48 h under natural photoperiod in early spring, midsummer, and autumn. The autumn recording was continued until the end of November on non-starved and starved snails. Two additional sessions were performed on torpid snails in January (latencies of arousals from torpor at various temperatures and immediate thermal preferences were recorded) and in February (they were kept permanently in darkness at 5 °C and their spontaneous arousals were examined). Temperature selected in spring (23.60 ± 0.15 °C) was significantly lower than that in summer (26.90 ± 0.05; P < 0.05) and in autumn (27.50 ± 0.10 °C; P < 0.01). The prolonged autumn recording did not show cold-seeking behaviour either in non-starved or in starved snails. Threshold temperature inducing midwinter arousals was 10 °C and the aroused snails immediately selected temperatures indistinguishable from those in summer and autumn. Spontaneous arousals from torpor in the snails continuously exposed to cold occurred within a period of arousals in the field. In conclusion, winter torpor of the snails displays unique properties, i.e., its start and maintenance are passive phenomena, while its spring interruption is a precisely controlled, endogenous mechanism.