DOI: 10.5061/dryad.73n5tb33p
title: Phylogenetic systematics of the enigmatic genus Horologion Valentine, with description of a new species from Bath County, Virginia (Coleoptera, Carabidae, Trechinae, Horologionini)

description: Horologion Valentine, one of the rarest and most enigmatic carabid beetle
 genera in the world, was until now known only from the holotype of
 Horologion speokoites Valentine, discovered in 1931 in a small cave in
 West Virginia. A single specimen of a new species from Virginia was
 collected in 1991, but overlooked until 2018. DNA sequence data from
 specimens of this new species, Horologion hubbardi sp. nov., collected in
 2022 and 2023, as well as a critical examination of the external
 morphology of both species, allow us to confidently place Horologion in
 the supertribe Trechitae, within a clade containing Bembidarenini and
 Trechini. A more specific placement as sister to the Gondwanan
 Bembidarenini is supported by DNA sequence data. Previous hypotheses
 placing Horologion in or near the tribes Anillini, Tachyini, Trechini,
 Patrobini, and Psydrini are rejected. The existence of two species of
 Horologion on opposite sides of the high mountains of the middle
 Appalachians suggests that these mountains are where the ancestral
 Horologionpopulations dispersed from, and predicts the discovery of
 additional populations and species. All specimens of H. hubbardi were
 collected in or near drip pools, and most were found dead, suggesting that
 the terrestrial epikarst, rather than caves, is the true habitat of
 Horologion, which explains their extreme rarity since epikarst has not
 been directly sampled. We recognize the tribe Horologionini, a relict
 lineage without any close relatives known in the Northern Hemisphere, and
 an important part of Appalachian biodiversity.
description: # Data from: Phylogenetic systematics of the enigmatic genus Horologion
 Valentine, with description of a new species from Bath County, Virginia
 (Coleoptera, Carabidae, Trechinae, Horologionini)
 This file is intended to
 be opened in Mesquite (). Contains DNA
 sequence data from eight genes, sampled from 259 carabid beetles. Matrices
 of individual genes and a concatenated matrix, as well as all trees
 resulting from analyses of this data, are included. When opened in
 Mesquite, it displays six tabs. The "Taxa" tab includes a list
 of the 259 beetles and their associated voucher codes, as well as GenBank
 accession numbers for each of the sequences obtained. The "Character
 matrices" tab is a list of the matrices of DNA sequence data in the
 file. The user may view each of these by right clicking and selecting
 "Show". The "Tree blocks" tab includes a list of trees
 obtained from maximum likelihood analysis of the DNA sequence data in the
 file. The last on the list is a block of hypothetical tree topologies used
 to test support of various clades. The last three tabs are tree windows.
 The one titled "IQ-TREE ML Trees" is a set of all of the Maximum
 Likelihood trees obtained from each matrix in the dataset, with one tree
 visible at a time. The user may scroll between these using the arrows in
 the upper left. The name of the tree, including the abbreviation of the
 gene, is visible at the bottom of the screen while viewing it. The other
 two tree windows, titled "Consensus of *IQ-TREE Bootstrap Trees
 (Matrix: 8gene" and "IQ-TREE UF Bootstrap Trees (Matrix:
 8gene.concatenated)" are showing a maximum likelihood consensus tree
 and Ultrafast Bootstrapping tree, respectively. By default, both are
 showing these tress from the concatenated 8-gene matrix. The user may view
 bootstrap trees from other genes by using the Tree menu; for the standard
 bootstrap consensus window, select "Tree&gt; Tree Block (for
 Consensus Tree)&gt;" and then select the block of Bootstrap Trees
 from the gene of interest; for ultrafast bootstrap trees, select
 "Tree&gt; Tree Block (for Tree Window)" and select the IQ-TREE
 UF Bootstrap tree from the gene of interest. The DNA sequence data in this
 file can be exported in a variety of formats and used in virtually any
 phylogenetic analysis program.