Graduation Year

2021

Document Type

Thesis

Degree

M.S.

Degree Name

Master of Science (M.S.)

Degree Granting Department

Biology (Integrative Biology)

Major Professor

Sean Doody, Ph.D.

Co-Major Professor

Heather Judkins, Ph.D.

Committee Member

Paul Larson, Ph.D.

Keywords

cryptic species, octopus, biodiversity, conservation

Abstract

The Pygmy Octopus Octopus joubini (Robson, 1929) is a small, shallow water species found throughout the Gulf of Mexico (GoM), western Atlantic Ocean and the northeastern Caribbean Sea (Mather, 1982; Jereb & Roper, 2014; Judkins, 2009). This species is believed to belong to a complex based upon morphological features including arm length, web depth, sucker size, egg size, hatchling ecology, and chromatophore coloration. It has been proposed that Octopus mercatoris, another pygmy species found in the GoM, may belong in this complex; however, no analyses have been performed to verify this claim. The present study incorporated morphological comparisons with genetic evidence in an attempt to resolve the confusion associated with the proposed Octopus joubini complex. The main objectives of this study were to [1] utilize COI and 16S rRNA markers to determine if O. joubini represents a complex in the eastern GoM and [2] if cryptic species were identified, determine if they have overlapping geographical ranges. Traditional systematics and molecular evidence were able to confirm that O. joubini represents a complex in the eastern GoM. I propose that O. mercatoris and O. joubini continue to be considered cryptic species due to a small sample size and subtle morphological differences observed in the present study. It is still uncertain if O. mercatoris represents a third species in the complex or is conspecific with Forsythe & Toll’s (1991) large egg species. The two species appear to have broad distributions with overlapping geographical ranges.

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