Topic
Spintharus
About: Spintharus is a research topic. Over the lifetime, 2 publications have been published within this topic receiving 22 citations.
Papers
TL;DR: The first molecular phylogenetic analysis of S. flavidus provides preliminary support for a complex and contested geological hypothesis and finds evidence for a single colonization of the Caribbean about 30 million years ago, coinciding with the timing of the GAARLandia landbridge hypothesis.
Abstract: The Caribbean island biota is characterized by high levels of endemism, the result of an interplay between colonization opportunities on islands and effective oceanic barriers among them. A relatively small percentage of the biota is represented by 'widespread species,' presumably taxa for which oceanic barriers are ineffective. Few studies have explored in detail the genetic structure of widespread Caribbean taxa. The cobweb spider Spintharus flavidus Hentz, 1850 (Theridiidae) is one of two described Spintharus species and is unique in being widely distributed from northern N. America to Brazil and throughout the Caribbean. As a taxonomic hypothesis, Spintharus "flavidus" predicts maintenance of gene flow among Caribbean islands, a prediction that seems contradicted by known S. flavidus biology, which suggests limited dispersal ability. As part of an extensive survey of Caribbean arachnids (project CarBio), we conducted the first molecular phylogenetic analysis of S. flavidus with the primary goal of testing the 'widespread species' hypothesis. Our results, while limited to three molecular loci, reject the hypothesis of a single widespread species. Instead this lineage seems to represent a radiation with at least 16 species in the Caribbean region. Nearly all are short range endemics with several distinct mainland groups and others are single island endemics. While limited taxon sampling, with a single specimen from S. America, constrains what we can infer about the biogeographical history of the lineage, clear patterns still emerge. Consistent with limited overwater dispersal, we find evidence for a single colonization of the Caribbean about 30 million years ago, coinciding with the timing of the GAARLandia landbridge hypothesis. In sum, S. "flavidus" is not a single species capable of frequent overwater dispersal, but rather a 30 my old radiation of single island endemics that provides preliminary support for a complex and contested geological hypothesis.
31 citations
TL;DR: It is hypothesized that in South America, a greater diversity of the genus across the geographical landscape will be found than predicted based on Levi's “widespread Spintharus flavidus” hypothesis, and continental efforts to sample the genus would be profitable, as this charismatic group likely harbors unappreciated diversity throughout the continent.
Abstract: Spintharus is a genus of spiders that contained only two species until 2018 when it was demonstrated that a 'widespread' species was instead composed of multiple short-range endemics. This note redescribes Spintharus gracilis Keyserling and describes a new species of Spintharus (Araneae, Theridiidae), S. leverger sp. nov., both based on specimens from Brazil. We also examine specimens from several additional localities in Brazil displaying variation consistent with patterns previously found within the Caribbean: geographically isolated and unique localities may contain independent species lineages. Given the limited number of specimens, profuse variation, and lack of DNA data from museum specimens, it is challenging to gauge the number of species in the observed material. Instead of describing these as new species here, we highlight this variation and hypothesize that in South America, a greater diversity of the genus across the geographical landscape will be found than predicted based on Levi's "widespread Spintharus flavidus" hypothesis. Our results suggest that continental efforts to sample the genus would be profitable, as this charismatic group likely harbors unappreciated diversity throughout the continent.
2 citations
Related Topics (5)
Performance Metrics
| Year | Papers |
|---|---|
| 2020 | 1 |
| 2015 | 1 |