Daniel L. Geiger

Stretch Coding and Block Coding: Two New Strategies to Represent Questionably Aligned DNA Sequences

Most coding strategies that address the problem of questionable alignment (elision, case sensitive, missing, polymorphic, gaps as presence/absence matrix) conflict with phylogenetic principles, particularly those relating to the concept of homology (shared similiarity explained by common ancestry). In some cases, the test of conjunction is failed. In other cases, characters that are coded ambiguously can lead to character-state optimization in the terminal taxa that conflicts with the original observations. Only data exclusion and contraction avoid these pitfalls. In highly dissimilar sequences additional character states can represent the available information. Two new methods that accomplish this—block and stretch coding—are introduced here. These two new coding strategies are not in conflict with the test of conjunction and do not contradict the original observations. They are comparable to coding practices with morphological data once the intrinsic differences due to character-state identity and topographical identity have been taken into account. It is suggested that, of the three recoding methods, the one is selected that preserves the maximum potential phylogenetic information as measured with the minimum number of steps required for the particular part of the data matrix.

A new scissurelloid genus and species (Mollusca, Gastropoda) from the Late Triassic Cassian Formation

Triassurella carnica n. gen. n. sp., a new scissurelloid limpet-shaped gastropod is described from the Late Triassic (early Carnian) Cassian Formation. It represents one of the few Triassic members of the slit-bearing non-nacreous vetigastropods of the Scissurelloidea-Fissurelloidea-group and suggests that diversity and disparity of this group are greater than previously known. Despite descriptive work on the Cassian fauna for more than 160 years, the Cassian Lagerstätte still produces new taxa. However, most of these new taxa are rare (sampling saturation) or minute (collecting bias).Triassurella carnica closely resembles the Recent hot vent limpetTemnocinclis and is probably closely related to it. In contrast toTemnocinclis, Triassurella lived in tropical shallow water. Thus, the finding ofTriassurella corroborates the on-shore/off-shore hypothesis for the vertical colonization of the ocean, which says that originations and innovations tend to occur first in near-shore, shallow-water environments and spread subsequently to deep-water off-shore environments.KurzfassungTriassurella carnica n. gen. n. sp., ein neuer napfförmiger Gastropode aus der Gruppe der Scissurelloidea, wird aus der obertriassischen (frühes Karn) Cassian-Formation beschrieben. Es handelt sich um einen der wenigen triassischen Vertreter der Schlitz tragenden, nicht perlmutterigen Vetigastropoden der Scissurelloidea-Fissurelloidea-Verwandtschaft. Dies legt nahe, dass diese Gruppe in der Trias diverser und disparer (vielgestaltiger) war als bislang angenommen. Obwohl über die Fauna der Cassian Formation seit mehr als 160 Jahren beschreibend gearbeitet wird, bringt diese Formation noch immer neue Taxa hervor. Jedoch sind diese Taxa entweder selten (Beprobungssättigung) oder sehr klein (Beprobungsverzerrung).Triassurella carnica ähnelt stark der rezenten Hot Vent NapfschneckeTemnocinclis und ist vermutlich nahe mit ihr verwandt. Im Gegensatz zuTemnocinclis lebteTriassurella in tropischem Flachwasser. Daher stützt die Entdeckung vonTriassurella die on-shore/off-shore Hypothese für die vertikale Kolonisierung der Ozeane, welche besagt, dass evolutionäre Neuerungen und neue Taxa tendenziell in flachen küstennahen Gewässern entstehen und sich dann auf tiefere, küstenferne Bereich ausdehnen.

New species of Scissurellidae, Anatomidae, and Larocheidae (Mollusca: Gastropoda: Vetigastropoda) from New Zealand and beyond

Thirteen new species of Scissurellidae (Scissurella regalis n. sp., Sinezona mechanica n. sp., Sinezona platyspira n. sp., Sinezona enigmatica n. sp., Sinezona wanganellica n. sp., Satondella azonata n. sp., Satondella bicristata n. sp.), Anatomidae (Anatoma amydra n. sp., Anatoma kopua n. sp., Anatoma megascutula n. sp., Anatoma tangaroa n. sp.), and Larocheidae (Larochea spirata n. sp., Larocheopsis macrostoma n. sp.) are described, all of which occur in New Zealand waters. The greatest geographic source of new taxa is the islands and underwater features off northern New Zealand. The new shell-morphological term “sutsel” is introduced for the area between the SUTure and the SELenizone.

Severnsia strombeulima n. gen. & sp. from Hawaii (Mollusca, Gastropoda: Caenogastropoda: Eulimidae)

The malacofauna of Hawaii is rather well-known, owing to Kay (1979) and Severns (2011). Both works stand out because they include a large number of the generally under-represented micromollusks (<5 mm). Here a striking new genus and species of a microsnail is reported from that region.