Discovery of a Cryptic Species Closely Related to Allosergestes pectinatus (Decapoda: Sergestidae) in the Gulf of Mexico and Florida Straits
Department
Marine Biology
Faculty Advisor
Heather Bracken-Grissom
Start Date
30-9-2020 1:00 PM
End Date
30-9-2020 2:00 PM
Abstract
The deep sea (>200m) is the largest habitat on Earth and the last unexplored frontier of our planet. Within the mesopelagic realm (200-1000m), a large proportion of biomass is comprised of deep-sea shrimp. As part of a large ongoing project to study deep-pelagic crustacean biodiversity, several new and cryptic lineages have been discovered. Shrimps within the family Sergestidae (Decapoda, Dendrobranchiata) can be studied to better understand pelagic fauna in the deep-sea. Here we describe a new sergestid species, Allosergestes amphitritus nov. sp., based on morphological and molecular data. This species is allied to the widely distributed species, Allosergestes pectinatus, and represents a cryptic lineage in the Gulf of Mexico. The specimens were collected during various research expeditions throughout the Florida Straits and Gulf of Mexico including cruises conducted by the DEEPEND consortium (Deep Pelagic Nekton Dynamics of Gulf of Mexico). All collected specimens from the genus Allosergestes were examined based on traditional morphological characters (spinuation, characters of maxilliped 3, shape of reproductive structures, etc) under stereomicroscope. The DNA-barcoding mitochondrial genes cytochrome oxidase I (COI) and 16S rRNA were amplified, aligned, and concatenated for molecular analyses. We used a maximum-likelihood approach (ML) to build a phylogeny and examined the evolutionary relationships between Allosergestes amphitritus nov. sp. and other species within Allosergestes. Additionally, we performed genetic distance analysis. Intraspecific genetic distance among Allosergestes resulted in a 10-12% difference, which is enough to characterize A. amphitritus nov. sp. as a separate species. Allosergestes amphitritus nov. sp. is morphologically similar to A. pectinatus but presents a spine on the dorsal end of the dactyl on maxilliped III. The phylogenetic tree also confirmed the separation of A. amphitritus nov. sp. from all other species within the genus. This new species increases the number of Allosergestes species richness in the Gulf of Mexico from 2 to 3. Allosergestes amphitritus nov. sp. is found to be present in the Gulf of Mexico in sympatric distribution with A. pectinatus. Taxonomic and systematic studies in the deep sea will lead to a better understanding of biodiversity under the threat of increased human impact in this region (i.e. deep-sea drilling).
File Type
Event
Discovery of a Cryptic Species Closely Related to Allosergestes pectinatus (Decapoda: Sergestidae) in the Gulf of Mexico and Florida Straits
The deep sea (>200m) is the largest habitat on Earth and the last unexplored frontier of our planet. Within the mesopelagic realm (200-1000m), a large proportion of biomass is comprised of deep-sea shrimp. As part of a large ongoing project to study deep-pelagic crustacean biodiversity, several new and cryptic lineages have been discovered. Shrimps within the family Sergestidae (Decapoda, Dendrobranchiata) can be studied to better understand pelagic fauna in the deep-sea. Here we describe a new sergestid species, Allosergestes amphitritus nov. sp., based on morphological and molecular data. This species is allied to the widely distributed species, Allosergestes pectinatus, and represents a cryptic lineage in the Gulf of Mexico. The specimens were collected during various research expeditions throughout the Florida Straits and Gulf of Mexico including cruises conducted by the DEEPEND consortium (Deep Pelagic Nekton Dynamics of Gulf of Mexico). All collected specimens from the genus Allosergestes were examined based on traditional morphological characters (spinuation, characters of maxilliped 3, shape of reproductive structures, etc) under stereomicroscope. The DNA-barcoding mitochondrial genes cytochrome oxidase I (COI) and 16S rRNA were amplified, aligned, and concatenated for molecular analyses. We used a maximum-likelihood approach (ML) to build a phylogeny and examined the evolutionary relationships between Allosergestes amphitritus nov. sp. and other species within Allosergestes. Additionally, we performed genetic distance analysis. Intraspecific genetic distance among Allosergestes resulted in a 10-12% difference, which is enough to characterize A. amphitritus nov. sp. as a separate species. Allosergestes amphitritus nov. sp. is morphologically similar to A. pectinatus but presents a spine on the dorsal end of the dactyl on maxilliped III. The phylogenetic tree also confirmed the separation of A. amphitritus nov. sp. from all other species within the genus. This new species increases the number of Allosergestes species richness in the Gulf of Mexico from 2 to 3. Allosergestes amphitritus nov. sp. is found to be present in the Gulf of Mexico in sympatric distribution with A. pectinatus. Taxonomic and systematic studies in the deep sea will lead to a better understanding of biodiversity under the threat of increased human impact in this region (i.e. deep-sea drilling).