Jonathan A. Campbell

We introduce a new benchmark dataset, Placenta, for node classification in an underexplored domain: predicting microanatomical tissue structures from cell graphs in placenta histology whole slide images. This problem is uniquely challenging for graph learning for a few reasons. Cell graphs are large (>1 million nodes per image), node features are varied (64-dimensions of 11 types of cells), class labels are imbalanced (9 classes ranging from 0.21% of the data to 40.0%), and cellular communities cluster into heterogeneously distributed tissues of widely varying sizes (from 11 nodes to 44,671 nodes for a single structure). Here, we release a dataset consisting of two cell graphs from two placenta histology images totalling 2,395,747 nodes, 799,745 of which have ground truth labels. We present inductive benchmark results for 7 scalable models and show how the unique qualities of cell graphs can help drive the development of novel graph neural network architectures.

A new snake species of the genus Rena is described from northern Jalisco, Mexico. The new species represents an isolated member of the R. dulcis group in the extreme southwest Mesa Central of the country. We redefine the R. dulcis and R. humilis groups within the genus Rena. The status of the other species allocated to these groups is discussed.

A new species of hylid frog is described from the southwestern edge of the Mexican Plateau from the states of Morelos and Mexico through Michoacán and Jalisco, reaching the Sierra Madre Occidental in Sinaloa and western Durango. The new species is part of the widespread Mexican hylid Sarcohyla bistincta (sensu amplo) complex, comprised of S. bistincta, S. pentheter, S. calthula, and S. ephemera. One subspecies of S. bistincta (labeculata) was proposed for an isolated population in Oaxaca. We restrict the group’s nominal species, S. bistincta (sensu stricto), to the Sierra Madre Oriental of Mexico and southward into the Sierra Madre del Sur of Guerrero and Oaxaca. Examination of type material places S. calthula and S. ephemera in the synonymy of S. labeculata (new combination). The species allied to S. bistincta, namely, S. bistincta, S. labeculata, S. pentheter, and the new species described herein, are diagnosed and described following recent suggested taxonomic changes and new available material.

The members of the genus Ecnomiohyla from Mexico and Nuclear Central America have had their taxonomic names applied inconsistently in the literature, notably with much confusion surrounding specimens from the Maya Mountains of Belize. We refer those individuals to E. minera and, based on examination of almost all known specimens of Ecnomiohyla from Mexico, Guatemala, Belize, and Honduras, provide revised diagnoses for the recognized species: E. echinata, E. minera, E. salvaje, and E. valancifer. These frogs are rarely encountered and some species have not been seen in many decades.