Exploring the Diversity of Capitella spp. Complex: Insights from New Zealand's Ecological Landscape

In this week's instalment, we return to the foundational aspects of taxonomy, delving into the intriguing realm of "classic" taxonomy and its potential to discover and describe previously unknown species. Furthermore, we are pleased to spotlight the noteworthy work of Layla Sudol, a former student of Paul, who, during a summer scholarship at Paul's recent employer, undertook a comprehensive investigation into the diversity of New Zealand's Capitella spp. in the vicinity of fish farms.
Contrary to past assumptions that C. capitata was a cosmopolitan species with global distribution, recent investigations, including the meticulous work by our colleague James, who redescribed C. capitata, revealed that many closely related species were misidentified as C. capitata. This revelation shattered the notion of global distribution, leading to an explosion in identifying species belonging to the genus Capitella worldwide, including within New Zealand.
Layla Sudol's research made significant contributions to this expanding body of knowledge. Through detailed examinations of characteristics such as the Thoracic chaetal formula, teeth per hook, and the number of genital spines, Layla identified 46 individuals fitting the description of C. cf. giardi (Mensil, 1897) out of the 107 individuals collected by Geoffrey Read (NIWA) and the Healthy Ocean team at Cawthron Institute. Notably, the individuals exhibited variations from the originally described C. giardi, challenging established assumptions.
An additional 32 individuals defied categorization within previously described species. In contrast, four more appeared to align closely with C. cf. capitata (Fabricius, 1780). However, subtle differences in the chaetal formula and the arrangement of teeth per hook suggested potential distinctions. Layla also noted a potentially juvenile species, hinting at connections to C. cf. aberranta (Hartman & Fauchald, 1971), C. cf. minima (Langerhans, 1880), C.cf. ovincola (Hartman, 1947), and another as yet undescribed species.
The significance of these findings extends beyond taxonomy, delving into the realms of ecology and evolution. Utilizing microscopes and DNA, we unravel the mysteries surrounding these 6 - 23 millimetre-long specimens, gaining insights into their diversity and environmental adaptations.
Our collaborative efforts with colleagues at the Instituto Oceanográfico da Universidade de São Paulo continue, and we wait for the opportunity to sequence fresh material. In the interim, Layla's preliminary results prompt further inquiry into these enigmatic species, especially considering their potential indicators of varying environmental conditions. For Layla's recent poster, additional information and similar projects, please don't hesitate to contact us at www.ocean-wolf.com. Join us in unravelling the secrets of the deep, one microscopic specimen at a time.