Expansion of the fern genus Lecanopteris to encompass some species previously included in Microsorum and Colysis (Polypodiaceae)

The fern genus Microsorum is not monophyletic, with previous phylogenetic analyses finding three lineages to group not with the type species, but to form a grade related to the 13 species of Lecanopteris. These three lineages have recently been recognised as separate genera: Bosmania, Dendroconche, and Zealandia. Here, we explore the morphological characterisation of Lecanopteris and these other three lecanopteroid genera. While the traditional circumscription of Lecanopteris has seemed sacrosanct, its defining morphological character states of rhizome cavities and ant brooding associations occur in other lecanopteroid ferns and elsewhere in the Polypodiaceae. Instead, we suggest that the morphological characterisation of an expanded Lecanopteris including the Dendroconche and Zealandia lineages is just as good, if not better, with the pertinent character states being the absence of sclerenchyma strands in the rhizome and at least some fronds having Nooteboom’s type 5 venation pattern. This wider circumscription is also better able to accommodate phylogenetic uncertainty, and it means that groups of species traditionally placed together in a single genus are not distributed across different genera. General users familiar with the narrower circumscription of Lecanopteris will not be significantly disrupted, because there is little geographic overlap with the lineages added to the genus. Consequently, we make new combinations in Lecanopteris for 11 species and one subspecies.

Bank Networks and Acquisitions

Does the predeal geographic overlap of the branches of two banks affect the probability that they merge, postannouncement stock returns, and postmerger performance? We compile information on U.S. bank acquisitions from 1984 through 2016, construct several measures of network overlap, and design and implement a new identification strategy. We find that greater predeal network overlap (1) increases the likelihood that two banks merge; (2) boosts the cumulative abnormal returns of the acquirer, target, and combined banks; and (3) reduces employment, boosts revenues, reduces the number of branches, improves loan quality, and expedites executive turnover. This paper was accepted by Tomasz Piskorski, finance.

Morphological and genetic distinction of Armases angustipes and A. miersii (Decapoda, Brachyura, Sesarmidae)

Among coastal crabs of the family Sesarmidae from the western Atlantic, there have been problems of misidentification and controversial reports of distribution, especially due to the morphological similarity and sympatric occurrence of some species. In order to clarify the morphological distinction between Armases angustipes and Armases miersii we here summarize morphological information of the two species and provide new information on the distribution of A. angustipes. In addition, museum specimens from the Bahamas assigned to A. angustipes were morphologically and genetically re-identified as A. miersii, questioning the occurrence of the former species in this archipelago. In this case, there would be no geographic overlap between the two species, with A. angustipes becoming the southern form, mostly restricted to South America. Further studies on the variability among populations of A. miersii and A. angustipes are needed.

Sympatric song variant in mountain chickadees Poecile gambeli does not reduce aggression from black-capped chickadees Poecile atricapillus

When habitats overlap and species compete for resources, negative interactions frequently occur. Character displacement in the form of behavioural, social or morphological divergences between closely related species can act to reduce negative interactions and often arise in regions of geographic overlap. Mountain chickadees Poecile gambeli have an altered song structure in regions of geographic overlap with the behaviourally dominant black-capped chickadee Poecile atricapillus. Similar to European and Asian tits, altered song in mountain chickadees may decrease aggression from black-capped chickadees. To test this hypothesis, we conducted a playback study in Prince George, BC, Canada, to examine how black-capped chickadees responded to the songs of mountain chickadees recorded in regions where the two species were either sympatric or allopatric. We used principal component analysis (PCA) to collapse behavioural response variables into a single ‘approach’ variable and a single ‘vocalisation’ variable. We then used mixed-model analysis to determine whether there was a difference in approach or vocalisation response to the two types of mountain chickadee songs (allopatric songs and variant sympatric songs). Black-capped chickadees responded with equal intensity to both types of mountain chickadee songs, suggesting that the variant mountain chickadee songs from regions of sympatry with black-capped chickadees do not reduce heterospecific aggression. To our knowledge, this is the only instance of a character shift unassociated with reduced aggression in the family Paridae and raises interesting questions about the selective pressures leading to the evolution of this song divergence.

Diversity, complementary distributions and taxonomy of Rhagada land snails (Gastropoda : Camaenidae) on the Burrup Peninsula, Western Australia

Phylogenetic diversity of Rhagada land snails is high on the Burrup Peninsula, Western Australia, with four distinct clades, representing three of the four major clades of the Pilbara region. Detailed sampling indicated little geographic overlap of the four clades, conforming to the general rarity of congeneric sympatry in Australian camaenids. The diversity on the Burrup Peninsula includes three previously unclassified morphotypes. One of these lies within the broad endemic clade of the adjacent Dampier Archipelago, and is provisionally assigned to the island species R. perprima, based on phylogenetic evidence. The two other undescribed morphotypes constitute an endemic clade that is the sister group of the broader Dampier Archipelago clade. All COI p-distances within clades are less than 6%, whereas nearly all distances between clades exceed 10%, the gap corresponding to differences among species of Rhagada generally. One morphotype in the Burrup Peninsula endemic clade has a low spire and a distinctive keel, and is restricted to a single rockpile. Detailed local sampling revealed gradation between this form and the more widely distributed globose morphotype. On the basis of genetic similarity and morphological continuity, we describe the morphologically variable endemic Burrup Peninsula clade as Rhagada ngurrana, sp. nov., which has a distribution spanning only 9 km.