Abstract
The Texas fauna of the genus Anillinus Casey, 1918 includes three previously described species (A. affabilis (Brues), 1902, A. depressus (Jeannel), 1963 and A. sinuatus (Jeannel), 1963) and four new species here described: A. acutipennis Sokolov & Reddell, sp. n. (type locality: Fort Hood area, Bell County, Texas); A. comalensis Sokolov & Kavanaugh, sp. n. (type locality: 7 miles W of New Braunfels, Comal County, Texas); A. forthoodensis Sokolov & Reddell, sp. n. (type locality: Fort Hood area, Bell County, Texas); A. wisemanensis Sokolov & Kavanaugh, sp. n. (type locality: Wiseman Sink, Hays County, Texas). A key for identification of adults of these species is provided. The fauna includes both soil- and cave-inhabiting species restricted to the Balcones Fault Zone and Lampasas Cut Plain and adjacent areas underlain by the Edwards-Trinity Aquifer. Based on morphological and distributional data, we hypothesize that four lineages of endogean Anillinus species extended their geographical ranges from a source area in the Ouachita-Ozark Mountains to the Balconian region in central Texas. There the cavernous Edwards-Trinity aquifer system provided an excellent refugium as the regional climate in the late Tertiary and early Quaternary became increasingly drier, rendering life at the surface nearly impossible for small, litter-inhabiting arthropods. Isolated within the Edwards-Trinity aquifer system, these anilline lineages subsequently differentiated, accounting for the currently known diversity. The paucity of specimens and difficulty in collecting them suggest that additional undiscovered species remain to be found in the region.
Highlights
Representatives of the subtribe Anillina are typically litter- or soil-dwelling carabids, but they are not common in caves
Of the approximately 50 anilline species previously described from North America, only four species of Anillinus (namely, A. longiceps Jeannel (1963a), A. smokiensis Sokolov (2011), A. tombarri Sokolov (2012), and A. valentinei (Jeannel 1963b) and both described species of the genus Anillaspis Jeannel can be considered true troglobitic species
During the last 10 years, the caves of central Texas have been intensely monitored because of conservation issues involving endangered troglobitic species threatened by urban development
Summary
Representatives of the subtribe Anillina are typically litter- or soil-dwelling carabids, but they are not common in caves. From adults of other Texan species of the genus, those of A. affabilis can be distinguished by the following combination of external characters: large size, comparatively narrow and transverse pronotum with rectilinearly constricted lateral margins, rather wide and long elytra with rounded apices; and males can be further distinguished by the minute spine on the posterior edge of metafemora and shape of the median lobe.
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